GGS Operating Manual Vol 1

PETRO-CANADA EBLA PALMYRA B.V Unit : GGS

00180-PCP-300-PDMan-12503-01 GGS Operating Manual Vol #1

Operations Page 2 of 275

EBLA GAS PROJECT

Document Title

GGS Operating Manual Vol #1

Document Number

00180-PCP-300-PD-MAN-12503-01

Type of Document

Manual

Rev

A1

Date

REVISION STATUS Description

Originator

08-10-09 Issue for Info-training RL Expiry Date of Procedure Life Cycle of review

APPROVAL Verified

AD

Approved




TABLE OF CONTENTS SECTION I 1.0 2.0 3.0 4.0 5.0 6.0 7.0

INTRODUCTION......................................................

ABBREVIATION................................................................................ TERMINOLOGY............................................................................... UNIT OF MEASUREMENT................................................................... OBJECTIVE OF OPERATION MANUAL.................................................. PREAMBLE..................................................................................... EMERGENCY SHUTDOWN.................................................................. INTENDED USERS............................................................................

SECTION II HEALTH, SAFETY AND ENVIRONMENT.......................... SECTION III HAZOPS & ROUNDS................................................. SECTION V GAS GATHERING STATION......................................... 1.0 INTRODUCTION............................................................ 1.1

OVERVIEW OF GAS GATHERING STATION.............................................

2.0

SPECIFIC SAFETY HAZARDS.............................................

2.1 2.2 2.2.1 2.2.2 2.2.3 2.3

GENERAL SAFETY PRECAUTIONS AND OPERATIONS.............................. HAZARDS IN HANDLING CHEMICALS................................................... Physical and Chemical Properties of TEG........................................... Physical and Chemical Properties of Methanol................................... Physical and Chemical Properties of Sodium Hypochlorite................... PPE REQUIREMENTS........................................................................

3.0

EQUIPMENT SPECIFICATION.............................................

3.1 METHANOL STORAGE TANK....................................................................... 3.2 METHANOL LOADING/UNLOADING PUMP............................................ 3.3 OPEN DRAIN NON-CONTAMINATED SUMP PUMP.................................... 3.4 OPEN DRAIN CONTAMINATED SUMP PUMP........................................... 3.5 CLOSED DRAIN DRUM...................................................................... 3.6 CLOSED DRAIN DRUM HEATER........................................................... 3.7 CLOSED DRAIN DRUM PUMP.............................................................. 3.8 LP PRODUCED WATER DISPOSAL PUMP...............................................

4.0

PROCESS AND CONTROL DESCRIPTION................................

4.1

PRODUCTION SEPARATOR.................................................................




4.1.1 Principle of Separation of Water from Oil in Separators...................... 4.1.2 Production Separator Controls......................................................... 4.2 FIELD GAS COMPRESSOR.................................................................. FIELD GAS COMPRESSOR SUCTION KNOCK-OUT DRUM........................................ FIELD GAS COMPRESSOR................................................................................ FIELD GAS COMPRESSOR AFTERCOOLER........................................................... 4.2.1 Process Description........................................................................ 4.2.2 Field Gas Compressor Controls......................................................... 4.3 CONDENSATE SYSTEM...................................................................... 4.3.1 PROCESS DESCRIPTION.................................................................... CONDENSATE PUMPS..................................................................................... CONDENSATE COALESCER............................................................................... CONDENSATE SOLIDS FILTER........................................................................... EARLY OPERATION CONDENSATE PUMPS........................................................... 4.3.2 Condensate System Control............................................................. 4.3.3 Condensate Coalescer Interface Level Control................................... 4.4 GAS DEHYDRATION SYSTEM.............................................................. 4.4.1 Process Description........................................................................ GAS DEHYDRATION COLUMN........................................................................... 4.4.2 Gas Dehydration Controls................................................................ 4.5 TEG REGENERATION SYSTEM............................................................ 4.5.1 Principle of TEG Regeneration System.............................................. GLYCOL CIRCULATION PUMPS.......................................................................... TEG BURNER AIR FAN..................................................................................... TEG MAKE-UP FILTER..................................................................................... TEG DRAIN VESSEL........................................................................................ TEG STRIPPING COLUMN................................................................................ TEG DRAIN PUMP.......................................................................................... TEG STORAGE TANK...................................................................................... TEG MAKE-UP PUMP...................................................................................... COLD LEAN/RICH GLYCOL HEAT EXCHANGER.................................................... HOT LEAN/RICH GLYCOL HEAT EXCHANGER...................................................... 4.5.2 Process Description........................................................................ 4.5.3 TEG Regenerator Controls............................................................... 4.6 TEG INCINERATOR SYSTEM............................................................... 4.6.1 TEG Incinerator Controls................................................................. 4.7 UTILITIES....................................................................................... 4.7.1 Plant Air System............................................................................. 4.7.2 Instrument Air System..................................................................... AIR COMPRESSOR.......................................................................................... INSTRUMENT AIR RECEIVER............................................................................




4.7.3 Nitrogen System............................................................................. NITROGEN RECEIVER..................................................................................... WET AIR RECEIVER........................................................................................ 4.7.4 Utility Water.................................................................................. UTILITY WATER TANK..................................................................................... BOREHOLE WATER PUMP................................................................................ UTILITY WATER PUMP.................................................................................... 4.7.5 Potable Water System..................................................................... POTABLE WATER TANKER UNLOADING PUMP..................................................... POTABLE WATER DISTRIBUTION PUMP.............................................................. 4.7.6 Diesel System................................................................................ 4.8 FUEL GAS SYTEM............................................................................ FUEL GAS KNOCK-OUT DRUM.......................................................................... FUELGAS HEATER.......................................................................................... FUELGAS SUPER HEATER................................................................................ 4.8.1 Fuel Gas System Control Description................................................ 4.9 FLARE SYSTEM............................................................................... FLARE KO DRUM........................................................................................... FLARE KO DRUM HEATER................................................................................ FLARE KNOCK-OUT DRUM BOOSTER PUMP........................................................ FLARE KO DRUM PUMP................................................................................... 4.9.1 Flare System Controls..................................................................... 4.10 PRODUCED WATER SYSTEM............................................................... 4.11 DRAIN SYSTEM................................................................................ 4.11.1 Open Drain System......................................................................... 4.11.2 Closed Drain system.....................................................................101 4.12 POWER GENERATOR SYSTEM...........................................................102

5.0

ELECTRICAL..............................................................106

5.1 5.1.1 5.1.2 5.1.3 5.1.4 5.2 5.3 5.4 5.5

ELECTRICAL SYSTEMS....................................................................107 Electrical System Controls.............................................................108 Electrical System Start-Up.............................................................110 System under Plant Normal Operating Condition..............................113 Electrical System – GTG Failure.....................................................114 EMERGENCY DIESEL GENERATOR SET...............................................118 MAIN HV SWITCHBOARD................................................................122 POWER TRANSFORMER..................................................................122 LV POWER DISTRIBUTION...............................................................123

6.0

INSTRUMENTATION......................................................127

6.1 6.2

INTEGRATED CONTROL AND SAFETY SYSTEM (ICSS)............................128 DISTRIBUTED CONTROL SYSTEM (DCS) – GGS....................................128




6.3 EMERGENCY SHUTDOWN SYSTEM (ESD) – GGS...................................132 Double Isolation Valves...............................................................................138

7.0

FIRE AND GAS............................................................141

7.1 7.2 7.3 7.4 7.5

FIRE & GAS – INTRODUCTION.........................................................142 FIRE DETECTORS..........................................................................143 ALERTING EQUIPMENT...................................................................143 FIRE ZONES..................................................................................146 HIGH-SENSITIVE SMOKE DETECTION SYSTEM (HSSD)..........................147

8.0

TELECOMMUNICATION..................................................150

8.1 8.2 8.3 8.3.1 8.4 8.4.1 8.5 8.6 8.7

TELECOM SUBSYSTEMS..................................................................151 SDH TRANSMISSION SYSTEM...........................................................151 TELEPHONE SYSTEM......................................................................152 Telephones..................................................................................152 RADIO SYSTEM.............................................................................152 Radio Tower.................................................................................153 ENVIRONMENTAL MONITORING SYSTEM............................................153 LOCAL AREA NETWORK..................................................................154 TELECOM SUPERVISORY SYSTEM......................................................154

9.0

PRODUCT SPECIFICATION..............................................155

9.1 9.2 9.3

GAS & CONDENSATE SPECIFICATION................................................156 GAS............................................................................................156 CONDENSATE...............................................................................156

10.0

PRE-REQUISITES FOR START-UP ACTIVITIES........................158

10.1 10.1.1 10.1.2 10.2 10.2.1 10.2.2 10.2.3 10.2.4 10.2.5 10.2.6 10.2.7

PRE-REQUISITE – SAFETY...............................................................159 Introduction................................................................................159 Safety.........................................................................................159 PRE-REQUISITE ACTIVITIES.............................................................159 Vessels and Pipelines....................................................................159 System Leak Testing and Purging....................................................160 HVAC in Control Room...................................................................160 Diesel and Chemicals....................................................................160 Checking of Functional Loop and Control Valves...............................160 Charging of Lubricants for Rotating Equipment................................160 L.P. Fuel Gas System.....................................................................161

11

START-UP OF UTILITIES AND OFF-SITE FACILITIES................162

11.1 11.1 11.2 11.3

SEQUENCE OF START-UP................................................................163 START-UP OF DIESEL SYSTEM..........................................................163 START-UP OF EMERGENCY POWER GENERATOR PACKAGE....................165 START-UP OF UTILITY WATER SYSTEM..............................................167




11.4 11.5 11.6 11.7 11.8 11.9 11.10 11.11 11.12 11.13 11.14 11.15

START-UP OF START-UP OF START-UP OF START-UP OF START-UP OF START-UP OF START-UP OF START-UP OF START-UP OF START-UP OF START-UP OF START-UP OF

POTABLE WATER SYSTEM.............................................168 PLANT AIR.................................................................169 INSTRUMENT AIR........................................................170 NITROGEN SYSTEM.....................................................171 FLARE SYSTEM...........................................................172 OPEN DRAIN SYSTEM..................................................173 CLOSED DRAIN SYSTEM...............................................174 FUEL GAS SYSTEM......................................................175 GAS TURBINE GENERATOR (GTG)..................................176 PRODUCED WATER SYSTEM..........................................182 METHANOL SYSTEM....................................................182 GLYCOL STORAGE AND TRANSFER SYSTEM.....................184

12.0

START-UP OF PROCESS PLANT........................................186

12.1 12.2 12.2.1 12.3 12.4 12.5 12.5.1 12.5.2 12.6 12.6.1 12.6.2 12.7 12.7.1 12.7 12.7.1

START-UP SEQUENCE OF GGS..........................................................187 PURGING OF HYDROCARBON SYSTEM..............................................188 Facility Leak Test with Pressurization of Feed Gas............................188 START-UP OF PRODUCTION SEPARATOR............................................189 START-UP OF THE CONDENSATE SYSTEM...........................................191 START-UP OF FIELD GAS COMPRESSOR (LP OPERATION)......................192 Purging of Feed Gas Compressor Circuit..........................................192 Start-up......................................................................................193 START-UP OF GAS DEHYDRATION SYSTEM.........................................199 Initial Start-up.............................................................................200 Start-up at normal conditions........................................................213 START-UP OF TEG INCINERATOR SYSTEM..........................................215 Pre-requisites before starting the TEG Incinerator...........................215 START-UP OF OILY WATER SYSTEM...................................................218 Line-up of Oily Water System.........................................................218

13.0

NORMAL OPERATION AND MONITORING.............................220

13.1 13.2 13.3

PRODUCTION SEPARATOR NORMAL OPERATION.................................221 GAS DEHYDRATION & TEG REGENERATION SYSTEM............................222 COMPRESSOR NORMAL OPERATION..................................................224

14.0

PLANT START-UP AFTER EMERGENCY SHUTDOWN................226

14.1 14.2 14.2.1 14.2.2 14.2.3 14.2.4 14.2.5

GENERAL EMERGENCY SHUTDOWN LEVELS - ESD1, ESD2 & ESD3.........227 PLANT START-UP AFTER ESD1 SHUTDOWN........................................227 Start-up of Utility Water Systems...................................................228 Start-up of Potable Water Systems.................................................228 Start-up of Plant Air System..........................................................229 Start-up of Instrument Air.............................................................230 Start-up of Nitrogen System..........................................................231




14.2.6 14.2.7 14.2.8 14.2.9 14.2.10 14.2.11 14.2.12 14.2.13 14.2.14 14.2.15 14.2.16 14.2.17 14.3 14.4 14.5

Start-up of Flare System...............................................................232 Start-up Open Drain System...........................................................232 Start-up Closed Drain System.........................................................233 Start-up of Fuel Gas System..........................................................233 Start-up of Gas Turbine Generator..................................................234 Start-up of Produced Water System................................................235 Start-up of Glycol Transfer System.................................................236 Start-up of Production Separator....................................................237 Start-up of the Condensate System................................................238 Start-up of Field Gas Compressor (LP Operation).............................239 Start-up of Gas-Dehydration..........................................................243 Line-up of Oily Water System.........................................................246 PLANT START-UP AFTER ESD2 SHUTDOWN........................................247 PLANT START-UP AFTER ESD3 SHUTDOWN........................................247 BLACK START-UP OF GGS...............................................................249

15.0 16.0

TROUBLESHOOTING OPERATION.....................................252 SHUTDOWN...............................................................260

16.1 16.2 16.2.1 16.2.2 16.2.3 16.3

PLANNED SHUTDOWN....................................................................261 EMERGENCY SHUTDOWN................................................................264 ESD Level-1 Shutdown...................................................................265 ESD Level-2: Process Shutdown......................................................265 ESD LEVEL-3: Unit/Equipment Shutdown.........................................267 DRAINING PHILOSOPHY/RECOVERY FOR START-UP.............................270

SECTION I

INTRODUCTION


1.0


ABBREVIATION

Acronym AC AMB API ATM BA BCS BDV BGU CCR CD CGR CNE CO2 CS CSO DB dB DBB DCS DE DP EDG ESD F&G FV FW FZ GC GGS GOR GTP H2S HC HH HMI HP HPS HSE I&C IS KCS

Expansion Alternating Current Ambient American Petroleum Institute Atmospheric Breathing Apparatus Burner Control System Blowdown Valve Break Glass Unit Central Control Room Closed Drain Condensate to Gas Ratio Cause and Effect Carbon dioxide Carbon Steel Car-Seal Open Double Block Decibel Double Block & Bleed Distributed Control System Drive End Differential Pressure Emergency Diesel Generator Emergency Shutdown Fire & Gas Full Vacuum Fire water Fire Zone Gas Chromatograph Gas Gathering Station Gas to Oil Ratio Gas Treatment Plant Hydrogen Sulphide Hydrocarbon High High Human Machine Interface High Pressure High Pressure Separator Health, Safety and Environment Instrument & Control Intrinsically Safe Killed Carbon Steel



Acronym KOD LC LCP LCS LCV LEL LL LO LP LPG LSS LTS MMSCFD MP N2 NC NDE NO NPSH O&M O/L ORP P&ID PB PCV PMS POM PPE ppm ppmv ppmw PSD PSV PTW ROV RTU RV RVP SB SBB SGS TCV TDS


Expansion Knock Out Drum Lock Close Local Control Panel Local Control Station Level Control Valve Lower Explosive Limit Low Low Lock Open Low Pressure Liquified Petroleum Gas Low Speed Side; Low Signal Selector Low Temperature Separator Million Standard Cubic Feet Per Day Medium Pressure Nitrogen Normally Closed Non-Drive End Normally Open Net Positive Suction Head Operation & Maintenance Outlet Oxygen Reduction Potential Piping and Instrumentation Diagram Pushbutton Pressure Control Valve Power Management System Plant Operating Manual Personal Protective Equipment Parts Per Million Parts Per Million by Volume Parts Per Million by Weight Process Shutdown Pressure Safety Valve Permit to Work Remote Operated valve Remote Terminal Unit Relief Valve Reid Vapour Pressure Single Block Single Block & Bleed Satellite Gathering station Temperature Control Valve Total Dissolved Solids




Acronym TEG TSS TVP UC UCP UPS WHCP WHFP WPT 2.0


Expansion Tri-Ethylene Glycol Total Suspended Solids True Vapour Pressure Utility Connection Unit Control Panel Uninterrupted Power Supply Well head Control Panel Well head Flowing Pressure Working Pressure & Temperature

TERMINOLOGY

Acid Gas Antifoam Agent API Gravity

Aromatics

Auto Ignition Point Balanced Draught Barrel Block Valve Catalyst

Ceramic Balls Coalescer Condensate Dehydration

Gas with H2S and CO2 content An additive used for controlling foam in some lubricating oils. It is used in DIPA (Di-Iso Propanol amine), Sulfinol and TEG Unit API degree is used for reporting the gravity of a petroleum product. The degree API is related to the specific gravity scale (15C/15C) by the formula: Degree API = (141.5/Sp. Gr. 15C/15C) – 131.5 A group of hydrocarbons having at least one ring structure of six carbon atoms, each of the latter having one valency outside the ring. Typical aromatics are: benzene, toluene, xylene, phenol (all mono-aromatics) and naphthalene (a di-aromatic) The temperature at which the vapour given off by a sample will burn in air without any ignition source A method of furnace air control using both forced and induced draught fans A standard measure of crude oil quantity; equivalent to 35 imperial gallons, 42 US gallons or 159 litres A valve used for isolation of equipment A substance added to a system of reactants which will accelerate the desired reactions, while emerging virtually unaltered from the process. The catalyst allows the reaction to take place at a temperature at which the uncatalyzed reaction would proceed too slowly for practical purposes. Used extensively in secondary processes Balls of chemically inert ceramic, used as filler and support in reactors etc. A vessel packed with steel wool, glass wool, polypropylene wool or felt used to remove fine droplets of treating liquids or water from a petroleum product Liquid separated from hydrocarbon gas in a Gas-Liquid Seperator which is typically having composition more than C5+. It is normally used as Petrochemical Feed stock. The removal of water from gas produced in association with oil, or



ESD Level-1 Shutdown ESD Level-2 Shutdown ESD Level-3 Shutdown Gas Turbine Hydrate

KOD

LEL LPG

Mercaptans

Mole %

Purging

Pyrophoric Schoepentoeter Sour Gas Stabiliser


from gas from gas-condensate wells ESD Level-1 shutdown will open all the depressurising valves at the same time ESD Level-2 shutdown will enable depressurisation, allowing for operator action if required ESD Level-3 shutdowns are used only to isolate or shutdown systems. Individual units/equipment may be depressurised if necessary An engine in which gas (as distinct from steam) is directed, under pressure, against a series of turbine blades. The energy contained in the rapidly expanding gas is converted into rotary motion A compound formed by the chemical union of water with a molecule of some other hydrocarbon. Gas hydrates, formed from water and, for example methane, may cause plugging of the tubing and flow lines of gas wells A vessel, constructed with baffles, through which a mixture of gas and liquid is passed to disengage one from the other. The heavier liquid particulates get separated from lighter gas due to gravitational force. Lower Explosive Limit - Leanest mixture that will explode. A greater air and hydrocarbon ratio will not ignite Liquefied Petroleum Gas is a mixture of Propane & Butane which can be stored under elevated pressure as a liquid at atmospheric temperatures (‘bottled gas’). It is widely used for cooking and domestic heating. Typically contains Propane≤30 Vol%, Butane≤ 70Vol% Mercaptans or alkyl-hydrosulphides are organic compounds of carbon, hydrogen and sulphur. They have a bad odour and frequently occur in unrefined gasoline. Ethyl Mercapton is added as an odorant in commercial LPG. An expression of the percent composition of a mixture in terms of moles. The relative numbers of moles are computed by dividing the numbers of units of weight of the individual constituents by their respective molecular weights The removal of one fluid from a vessel or plant by introduction and subsequent evacuation of a second fluid. A common usage of this operation is in the removal of hydrocarbon vapours or air from a plant by flushing with nitrogen Catches fire spontaneously upon contact with air. Certain forms of iron sulphide exhibit this tendency (Pyrophoric iron) An internal distribution device, sideways or downwards pointing. Gas which contains objectionable amounts of contaminants, e.g. hydrogen sulphide and other corrosive sulphur compounds A fractionating column designed to make a sharp separation between very volatile components and gasoline from Naphtha, casing head gasoline or pressure distillate, thus controlling the gasoline’s Reid vapour pressure



Stripping

Total Suspended Solids Turn Down

3.0

Page 14 of 275

Removal of the lightest fractions from a mixture. The process is usually carried out by passing the hot liquid from a flash drum or tower into a stripping vessel or stripping section of a column, through which open steam or inert gas is passed to remove the more volatile components of the cut A water specification with undissolved solid matter greater than 1.5 microns Amount or percentage by which a unit or plant may be turned down from its rated capacity. Typically 40% is the minimum. (The plants are designed to run at/or close to maximum)

UNIT OF MEASUREMENT

BOPD BPD BWPD CFD kg/h kW M m3/h mg/l MM MMSCFD Nm3/h ppb ppmv ppmw S STOBPD

4.0

Operations

Barrels of Oil Per Day Barrels Per Day Barrels of Water Per Day Cubic Feet Per Day Kilogram Per Hour Kilowatt Thousand Cubic meter Per Hour Milligram Per Litre Million Million Standard Cubic Feet Per Day Normal Cubic Meter Per Hour Parts Per Billion Parts Per Million by Volume Parts Per Million by Weight Standard Conditions at 15°C and 1 atm Standard Oil Barrels Per Day

OBJECTIVE OF OPERATION MANUAL

The objective of this manual is to guide and provide an overview of the GGS facilities, and a detailed description of Process and Control, Start-up and Shutdown of the plants. These manual details the safety measures, built-in protections employed, handling of emergencies in operation and start-up of the GGS facilities. This manual is to be used in conjunction with other vendor manuals; it summarizes various aspects of engineering including process, mechanical, electrical and control & instrumentation.




The manual describes process, utilities, offsite, the activities required for the plant start-up and shutdown, and, controls and safety hazards in the plant in various sections as detailed below: o

Section 1: A general introduction of the facilities

o

Section 2: HSE aspects

o

Section 3: Equipment Specification

o

Section 4: Process and Control Description

o

Sections 5 & 6: Electrical, Instrumentation and Emergency shutdown (ESD)

o

Section 7: F&G systems

o

Section 8: Telecom

o

Sections 9, 10 and 11: Product Specification, Pre-Requisites for Start-up and Startup procedures for Utilities.

o

Sections 12, 13 and 14: Plant Start-up, Normal Operating & Monitoring and Plant Start-up after Emergency Shutdown.

o

Section 15 & 16: Troubleshooting Operations and Shutdown procedures.

o

The Annexure Section contains Plot plan, PFD, Heat and Material balance, Alarms & Trip schedule, Cause & Effect diagram, Utility summary and Vendor Operation Manual references.

Though plant safety aspects are addressed in detail, this manual is not intended in any way to supersede safety practices approved by the Company and/or adopted as per manufacturers’ standards that should be followed by all personnel involved with these facilities. Step-by-step instructions and procedures for plant Start-up operations are discussed and should be used as a guideline . However it is cautioned that all scenarios and emergencies arising during plant operation cannot be visualized and explained in an Operating Manual. 5.0

PREAMBLE

Ebla Production Facilities consist of Well heads & Flowlines, Gas Gathering Station (GGS), Trunk line and Gas Treatment Plant (GTP). The production capacity of the plants is rated for 80 MMSCFD of Gas and 22.5 m3/h of Condensate. There are seven Gas Production Wells in Ash-Shaer facilities. The Well Fluid comprises of Gas and Condensate. The well fluids are transported to manifolds through trunk lines and then to a high pressure Production Separator in GGS. The Production Separator is a threephase separator vessel where the gas, condensate and produced water are separated. The field reserve profiles indicate that the well-pressure will be high during the initial phase of production and then the well-pressure will be reduced substantially. Hence the production operation is termed as Initial-Phase (HP-Phase) and Normal Operation (LP-Phase) of the Project. During the HP production phase, the pressure in the well




head is adequate for transportation of fluid to GTP, located 76 km away from GGS. However during the LP Phase, a Field Gas Compressor and High Pressure Booster Condensate Pumps are installed in GGS to compensate the pressure loss during transportation to GTP, processing at treatment plants in GTP and then to export the gas to the existing high pressure gas grid in Syria. The gas from Production Separator is dried in Glycol-operated Dehydration Unit (moisture: 1.5 lb/MMSCF); similarly the water content in Condensate (water specification: 200 ppmv) is removed before transporting to GTP. The condensate and dried gas are mixed and then transported to GTP through a Trunk line. At the Gas Treatment Plant (GTP), the gas and condensate are received in a Slug Catcher which knocks off the condensate from the gas. The condensate is sent to a Stabiliser which produces stabilised condensate and is sent to Condensate Storage Tanks. The gas from the slug catcher is sent to Gas Dehydration Unit which contains Molecular Sieves to remove the moisture down to 0.1 ppmv level. The cooled gas from Turbo-expander exchanges its heat with incoming feed gas and is recompressed in Expander-Compressor to 36 barg. The dried gas pressure is boosted in a Sales Gas Compressor and exported through Sales Gas Grid. The liquid separated from the cooled gas (Turbo-Expander) and the Low Temperature Separator flows to De-ethanizer for removal of uncondensed C1 and C2 components; this is then compressed and recycled to the suction of Sales Gas Compressor for export. The De-ethanizer bottoms are sent to De-butanizer to separate Stabilised Condensate and LPG. The LPG is dosed with an odorant (Ethyl Mercapton) in a dosing facility and sent for LPG truck filling. Condensate flows to storage tanks from where it is exported. Both GGS and GTP are provided with utilities such as Plant Air, Instrument Air and Nitrogen Generation Unit. Also Gas Turbo-Generators and Emergency Diesel Generators are provided in GGS as well as GTP. Both units are provided with Utility Water and Potable Water Systems. Fire Water System is provided only in GTP. The plant operations are executed with DCS at both units. The GTP has the provision to operate GGS and Well heads from its Control Room. 6.0

EMERGENCY SHUTDOWN

The Emergency Shutdown (ESD) system forms an integral part of the overall Plant Safety system. A separate ESD system is provided at Wellheads, GGS and GTP. The ESD system at GGS and GTP shall operate on three hierarchical levels, namely ESD-1, 2 & 3. ESD Level 1: This represents the highest level of emergency that may occur at the facility. ESD Level-1 will shutdown and depressurize the Process facilities. ESD Level 2: This is activated in the event of a significant process abnormality at the facilities. Operation of the facility shall be stopped by closing dedicated XVs and tripping all process equipment. ESD Level 3: ESD Level-3 shutdown is non-emergency process abnormalities affecting only one equipment item or unit. ESD Level-3 trips are provided primarily for equipment protection like shutdown of a Compressor on High-High discharge temperature and shutdown of Glycol Dehydration unit on High-High level in the Inlet Separator.


7.0



INTENDED USERS

It is intended that this manual be used by the Operating Personnel to give equipment description, system control and a start-up guideline .Note: the start-up section is intended as a guideline and not to replace the Operating Procedures .




SECTION II HEALTH, SAFETY AND ENVIRONMENT




COMMITTMENT TO TOTAL LOSS MANAGEMENT It is a fundamental commitment of Petro-Canada Syria to safely manage all risk which could impact its Employees, Contractors, Stakeholders, Environment, and Assets by:  providing a safe work environment;  developing the competency of a well-trained and knowledgeable workforce;  protecting the health, security and well-being of employees;  avoiding, minimizing or safely managing the impacts of our operations on the natural environment and on the communities in which we operate;  dealing openly with stakeholders who may have an interest in our operations or development projects;  supporting research on the health and environmental effects of our products, processes and wastes;  avoiding waste and conserving energy and natural resources;  setting and reviewing prudent, health, safety and environmental targets; and  establishing appropriate programs aimed at compliance with applicable regulatory standards. To support these goals, Petro-Canada incorporates a Total Loss Management (TLM) system in its business and operations. TLM serves as the company's overarching framework for health, safety and environmental performance. This provides clear management expectations; detailing employee responsibilities and serving as a mechanism for ongoing stewardship and continuous improvement through a program of regularly scheduled facility inspections and audits. Petro-Canada will make efforts to inform workers, governments, customers and the public about potential hazards inherent in the nature of our work or in the products we handle and sell. The Company recognizes that each worker has a vital role in protecting themselves, others and the environment from potential hazards. Our managers, employees and others engaged on our behalf are expected to carry out their duties in a manner designed to protect themselves, their fellow workers, the public, the environment and the physical assets of the Company. Guidance is available to customers in the safe handling of our products during transport, storage, use as well as recycling or disposal methods. We are prepared to respond to unplanned events with suitable emergency response plans and management processes should the need arise.







HEALTH, SAFETY and ENVIROMENT at the EBLA Gas Project As you read the technical information in this manual, you must also be aware of some of the hazards and risk involved in the operation of the GGS. To assist in mitigating these risks to an acceptable level, various tools have been developed and are available to provide all workers in ultimately working towards achieving Zero Harm. Although not fully inclusive, the following are some of the risk that may be encountered or associated with the operation of the GGS:  Hot & Cold equipment and process temperatures  Pressure  Trip Hazards  Heat Exhaustion  Chemical Exposure ( Inhibitors etc.)  Nitrogen  Hydrocarbons  Noise  Fall hazards  Back& Hand Injuries  Spills HEALTH AND SAFETY:

Safety-starts with you! It is the expectation that everyone must follow all Codes of Practice, site specific procedures and work instructions, and wear the proper Personal Protective Equipment at all times when performing their assigned task/job. Although not fully inclusive, the following are some of the tools that will assist you in eliminating or reducing the Risks and Hazards:

 Safety hard hats  Safety boots  Safety glasses  Ear Plugs/Muffs as posted  Coveralls FRC  Gloves  Codes of Practice




 Job Safety Analysis (JSA)  Training  Procedures and work instructions  Site Inspection / audits  Event Reporting  Pre-job meeting (tool box talks), and  MSDS (Material Safety Data Sheets) are provided to identify the potential hazards and the proper method for to handling of all chemicals used or produced on site.

One of our basic and simple principles is to determine which behaviors lead to incidents occurring, and then initiate improvement to our Management Systems to eliminate or reduce the unsafe behaviours and incident potential. The most effective and pro-active method of avoiding accidents is through a worker to worker behaviour based safety process. This is a worker observation process designed to help identify unsafe behaviours, unsafe acts and/or unsafe conditions before they can cause a loss. Task Risk Assessments will be incorporated into the work scope for the operation of the EBLA Gas Treatment Project. The Risk Assessment process is an essential component to ensuring the safe and efficient operation. All mitigation measures that are identified must be implemented to reduce the risk to as low as reasonably practicable. Environmental: Effects to the environment were considered during the design phase for this new facility. Some of the equipment in the plant that has been designed to protect the environment are:  flaring systems,  closed drain system,  open drain system with holding ponds and  spill kits. Housekeeping is a key part of maintaining a safe and clean working environment. The Ebla Gas Treatment Project has also developed a waste management strategy for items like filter disposal. ALWAYS REMEMBER – IF IN DOUBT, ASK! For further information or assistance contact your supervisor or HS&E representative.



SECTION III HAZOPS & ROUNDS





The following list are the Hazops action items that must be followed to ensure the safety of personnel and equipment damage Hazop Action No. 372 Confined space entry shall be as per company PTW procedure. It may be required to inspect the vessel internals or repair a vessel/drum or Closed Drain Drum boot. After draining the vessel and purging with N2, it should be dampened by water source to avoid any fire due to pyrophoric iron deposits. Also purge it for sufficient time such that the vessel is free from H2S/hydrocarbon content before vessel entry. There should not be any traces of H2S in the vessel before vessel entry. Proper PPEs should be used for vessel entry against H2S/Hydrocarbon presence. Hazop Action No. 30 Special precautions need to be taken on Vessels like Production Separator prior to releasing them to Maintenance/Turnaround Inspection. Even though H2S content is less than 100 ppm there will be considerable accumulation of pyrophoric scale over a prolonged period of operation. The pyrophoric dust will catch fire when it is exposed to atmosphere. Before opening the Vessel, the Separator shall be dampened from a water source. Disposal of the pyrophoric dust/scale shall be as per Company procedure for disposal of hazardous waste and shall not be dumped in Plant areas which will lead to fire accidents. Pyrophoric fire prevention measures are to be put in place (including availability of relevant portable fire extinguishers) Hazop Action No. 67 Handling and disposal of Contaminated filter Cartridges / Coalescer elements should be done in a safe manner. As these filters contain hazardous sulphur and nitrogen compounds this should be collected and disposed in designated storage areas. Proper PPE’s precautions to all personnel involved in handling the contaminated equipments to waste storage area. Hazop Action No. 31 When releasing Condensate/Produced Water Storage tanks, Condensate pumps/Filters, proper safety precautions are to be taken as per PTW Procedures and for vessel entry by Personnel. Check for Oxygen/Toxic HC components. The vessels are damped from a water source to avoid pyrophoric iron fires. Naturally Occurring Radioactive Material (NORM) and Low Specific Activity (LSA) Scale can appear during the drilling and process phases of Oil and Gas exploration and tend to deposit along with other scale. Low Specific Activity scale (LSA) which are found adhering to pipe and equipment internals produce potential radiation illness mainly due to Radium-226 produced from the decay of naturally occurring Uranium-238. Hence Radioactive Detection and PPE’s for protection against potential radiation illness should be used. The waste removed from Condensate storage/Produced water storage tanks/cartridge filter should be disposed off at locations specifically marked/designated as Waste holdup/storage area. The Waste disposal area shall be clearly fenced, marked and identified with safety tags/boards indicating warnings/dangers due to radioactive substances.




o Personnel involved in the operation should wear Breathing Apparatus (BA) sets o Flange is broken and hydrocarbon concentration measured o Purging using N2 continues, as necessary o When hydrocarbon concentration drops below 10 ppm, the ‘All Clear’ is given and normal work activities can recommence Hazop Action No. 384 The capacity of the Holding Pond is designed for the worst rainfall conditions. Partially open manual valves in the Water Disposal Pumps will cause overflow of water from the Holding pond to be spilled over to the surrounding environment. Normally the Holding pond receives non-contaminated water from the Open Drain Sump and Storm water. If entrained oil is present in the Holding Pond, it can be recycled to the open drain sump for reprocessing. Under these conditions of entrained oil in the Holding pond, over flow of water from Holding pond will create environmental problems. A portable skimmer can be employed to remove traces of oil in the Holding Pond so that at any time the water is free of oil in the Holding pond. A portable skimmer available at GTP also could be used. If heavy rainfall occurs for a considerable period, a separate Operator can be stationed round the clock to monitor the Levels and quality of water for the Open Drain System. Hazop Action No. 391 The contaminated water from the Open Drain Sump is pumped by Open Drain Contaminated Sump Pump (332-P-002A/S) to Produced Water Storage Tanks through a check valve and 3” dip pipeline with a siphon breaker. If Check valve is passing and water level is below dip leg level, then there will be gas migration from Produced Water tank to Contaminated Open Drain Sump. Hence the Operating personnel should ensure water level above dipleg and then only open the valve to the Contaminated Sump Drain Pump which will prevent gas migration and thereby avoiding potential Fire and Explosion hazard. Hazop Action No. 1200 Analyse Diesel quality prior to unloading from Diesel Truck. The diesel quality shall meet the specification including water content of less than 1000 ppm free water. After the Diesel unloading into the Diesel tank 322-T-001receipt, proper settling time to be given so that water settles and water is drained out from the bottom drain of the tank. Again check diesel quality by taking a sample at the outlet of Diesel Filter Coalescer. The water content shall be less than 100 ppm. This sampling should be done during normal operation to ascertain the quality of diesel and proper functioning of Diesel Filter Coalescer. Hence proper monitoring of Diesel quality shall be ensured. Otherwise water in diesel more than specification will cause loss of ignition in EDG.




Hazop Action No. 1203 The Diesel tank (322-T-001) is also provided with heating coils which can be used during winter when the temperature may reach below sub zero. Maintain proper temperature of diesel in the Diesel tank so that high water content does not lead to ice formation and thereby choking filter/pipeline. Ensure to drain water from Coalescer periodically to maintain diesel quality. Hazop Action No. 1195 Transfer diesel from Diesel Tank (322-T-001) to EDG by monitoring tank level when the level in the Day tank is low. Transfer diesel from Tank with 322-P-001A/S pump to day tank and closely watch the Day tank level. Malfunction of the Day tank float valve will lead to diesel overflow/spill and possible fire hazards. Hence an operator has to manually check and ensure proper coordination while filling day tank of EDG. Hazop Action No: 550 Monitor the dewpoint analyzer (325-AI-4520 for Train-A and 325-AI-4570 for Train-B) for Train-A continuously and ensure the dewpoint is maintained at -350C at 7.5 barg. If the dewpoint increases to -340C at 7.5 barg, immediately high alarm 325-AIH-4520 is activated. Always keep the standby Air Drier regenerated and kept ready so that it can be lined-up immediately if there is high dewpoint alarm. Excessive content of moisture in Instrument air may create accelerated corrosion in downstream users. Hazop Action No-300 The Methanol transfer to Tank 329-T-001 as well as tote tank is carried out using 329-P001A/S. Ensure there is always continous supply of LP fuel gas for the blanketing of Methanol Storage Tank 329-T-001. During methanol transfer ( Either to storage Tank 329-T-001 or to tote tank) if there is outage of LP fuel gas, stop the methanol transfer immediately. The transfer/unloading of methanol during LP fuel gas outage will lead to oxygen ingress into the tank and mix with oxygen to form a potentially explosive mixture. Hazop Action No. 26 In case of extended shutdown period during winter conditions, the water in the Produced water lines from Production Seperator should be completely drained. During Start-up, line-up heat tracing for all instruments and process lines before start-up. Ensure to switch “ON” heat-tracing lines for Produced water lines so as to avoid ice formation in water lines and reduce corrosion. While Start-up after Prolonged/Annual shutdown in winter, ensure to fully drain the Produced water lines so that freezing of the water lines are avoided. It is also recommended to drain out Produced water lines when the plant is taken on line after Annual shutdown. Failure of the heat tracing will lead to ice formation in the produced water lines and this will result to water carryover in condensate and causes accelerated corrosion in the pipeline.




Hazop Action No. 758 Drain the liquid accumulated in the Vent Gas KO Drum (305-V-003) by observing the Level gauge 305-LG-3135. If it is prolonged shutdown drain KOD and also ensure to switch on the heat tracing on the pipelines to maintain the fluidity in the line. The Field operators should ensure regular observance of the Vent Gas KOD liquid level and drain the liquid at frequent intervals. If the level builds up, then entrainment to Blowers will cause potential damage to the Blowers. Drain the Blowers casing of the selected Vent Gas blowers 305-K-002A/B or C/D by opening eight ball valves on each Blower casing assuring that all possible condensate is drained off before burner ignition and then close the drain valves. Hazop Action No. 757 In cold weather conditions TEG (Tri-Ethylene Glycol) is viscous and has to be warmed up to facilitate pouring. 





During winter months, when air temperature might fall to -15°C (min. ambient temperature) ascertain that Gas Dehydration Column bottom, the wet condensate outlet line and the chimney tray portion of the column are heated by electrical tracing. Switch on the electric tracing system on the level instruments installed on the Flash Drum 305-V-002, on the TEG Reboiler 305-H-001, TEG Surge Drum 305-V-005, stand-by pump and in general where electrical tracing is given. Increased viscosity of glycol in Surge vessel may affect the pumping and potentially damage the glycol circulation pumps at cold operating conditions. As the glycol lines are heat traced and insulated to retain the hot condition, it becomes necessary to restart the electrical heat tracing and then start the Glycol Pumps especially after prolonged shutdown and cold winter conditions.

Hazop Action No. 767 Check for potential leaks in the glycol circuit and arrest leaks on TEG lines wherever possible. Look for potential leaks like foaming in Contactor, escape of TEG vapours from TEG Reflux Condenser and Glycol pump gland leaks and top up when required. If the Glycol surge drum level reaches the LLLL value (305-LALL-3116) of 300mm, it will cause tripping of Glycol Pumps. Loss of Glycol circulation will lead to off-spec dehydrated gas as indicated 305-AIH-3022. Due to this water carryover it will cause accelerated corrosion of the trunk line. In case of losing glycol circulation and initiation of off spec gas alarm 305-AIH-3022 the operator has to initiate ESD-3 trip of Gas Dehydration Package. Hazop Action No. 766 Operator should inspect the Vent Gas KOD (305-V-003) level by monitoring liquid level of KOD at regular intervals by observing level gauge 305-LG-3135. Check the Liquid trap installed on the drain line of the Vent Gas KOD for its operability. Ensure to drain the liquid periodically with care to avoid gas blow-off. If the liquid level is higher it should




be drained to avoid carryover to Vent Gas Blowers (305-K-002A/B/C/D) and causing potential damage to the Vent Gas Blowers. Hazop Action No. 42 During the Start-up phase, the Gas Dehydration pressure is controlled by operating 305PV-3024. After stabilization of unit, the Dehydration column pressure control is switched over to Split Range controller 305-PIC-3009. In case of inadvertent action to open 305PV-3024 fully, will result in depressurisation of the Dehydration Column. This lower pressure will lead to lower efficiency of the Dehydration column. The following trouble shooting points alerts the Operator in case of inadvertent opening of 305-PIC-3024:  The operator will be alerted at 80.6 barg by Low pressure alarm 305-PAL-3009 and should take immediate action to identify the cause and close 305-PV-3024  High flow alarm in the Flare Header by 331-FAH-5126.  The bigger control valve 305-PV-3009A closes fully and the pressure is controlled only by smaller control valve 305-PV-3009B However if the Operator does not respond to the above mentioned alarms at 80.6 barg, then at 76.3 barg, the actuation by 305-PALL-3012 will cause ESD-3 shutdown which will cause unnecessary flaring at the upstream section of GGS. Hazop Action No. 47 The ESD-3 shutdown of Gas Dehydration/TEG Regeneration unit closes 305-XV-3001, the TEG Column 305-C-001 Bottom liquid outlet ESD valve. After the ESD shutdown the steps of glycol circulation, Heat-up of Glycol and the pressurisation of feed gas and the other requirements are to be followed as given below in Section 12.6.2. If the glycol circulation, Gas pressurisation and other set of requirements are not followed, it will lead to foaming which will cause glycol carry over to the trunkline. Hazop Action No. 43 If ESD-3 trip is actuated by initiation of 305-PALL-309 (due to inadvertent action of fully opening 305-PV-3024), the Condensate injection to the trunkline should be stopped if it is a prolonged ESD-3 shutdown. Immediately after the ESD-3 trip, the Production Separator can be operated near turndown capacity to avoid excessive flaring and condensate can still be routed to the Trunk line. For prolonged durations of ESD-3 shutdown, the condensate injection to trunkline should be stopped. . Injection of Condensate into the trunkline without dehydrated gas will accelerate corrosion in Trunkline and cause slug receipts at the GTP. Ensure TEG Incinerator is running with fuel gas and maintain the TEG circulation. Reset and start firing the TEG Regeneration Reboiler and stabilise the Gas Dehydration system before lining up condensate and dehydrated gas to the Trunkline. Hazop Action No. 27 If the Plant is taken for Annual/Long shutdowns, it is required to drain all the Produced water lines to prevent ice formation and corrosion of pipeline.. In case of failure to switch on heat tracing, will lead to blocking of Produced water lines and thereby increases water level in Production Separator. This will lead to water carryover in condensate and




corrosion in the Trunkline. Hence a regular schedule should be prepared to do regular monitoring and preventive maintenance of the Heat Tracing. Hazop Action No. 67 Handling and disposal of Contaminated filter Cartridges/Coalescer elements should be done in safe manner. As these filters contain hazardous sulphur and nitrogen compounds this should be collected and disposed in designated storage areas. Proper PPEs as given in Section 2.3 and Precautions should be given to all personnel involved in handling the contaminated equipments to waste storage area. Hazop Action No. 522: Any leak in the Dry gas/Lean TEG Exchanger will lead to glycol carryover along with dehydrated gas. This will result drop in Surge drum level and initiates an Low level alarm (305-LAL-3115) due to loss of glycol. As there is no isolation bypass available for the shell & tube sides, unit has to be shutdown if leak develops on either side. As there is a potential leakage due to corrosion of the 305-E-004 tube bundles, proper monitoring has to be done which will reduce the 305-E-004 tube bundle leakages. 

Proper monitoring of corrosion coupon 305-CC-3080 on the Gas Dehydration Column overhead vapour line. If corrosion rate is more increase the corrosion inhibitor injection rate at the outlet of TEG carbon filter.  A spare tube bundle availability helps in quick start-up of the Gas Dehydration plant in case of any leak  Provide isolation and bypass valves for both shell and tube side. Note: During winter period (when the ambient temperature falls below –15C), drain the column bottom and condensate outlet pipeline to column bottom, in order to avoid liquid freezing. In case of longer shutdown during winter, glycol also need to be drained for non- traced lines in order to avoid freezing due to the lower ambient temperatures (–15°C) and TEG freezing temperature of –7°C. Hazop Action No. 360 The Closed system will be positively isolated from the process by closing of valves at equipment during normal operation. The draining to Closed Drain drum is done one equipment at a time to have a better control and draining so as to avoid overflow of Closed Drain Drum. At any time, two equipments will not be drained simultaneously. Draining of more than one equipment may lead to liquid build-up in Closed drain drum and liquid carryover to the Flare header which is undesirable. Hence proper coordination should be planned in advance regarding the draining of liquids from equipments during shutdown. Where equipment is connected to a Closed Drain System for draining prior to Maintenance or inspection positive isolation for e.g. a spectacle blind will be provided between the equipment and the drain. The drain will be positively isolated during normal operation and the draining will be performed after shutdown and depressurization of the equipment item. The only exception is draining of Oil pad from Produced Water storage




Tank (334-T-001) and contaminated water storage tank (834-T-001) at GTP. Pressurized draining will be allowed during start-up like draining of Compressor casing drains. For drains which need to be used under normal operation like level instruments/bridle drains, the spectacle blind is left in open position and operators will turn it closed as and when required for equipment isolation. Consequently intermittent drainage required during normal operation will be returned to the process. Hazop Action No. 961 When the Gas Dehydration Plant is shutdown for longer periods during winter, then TEG needs to be cooled sufficiently and drained to TEG Drain vessel.   

Hazop Item # #766

Draining Hot TEG above 60C will damage drain piping and also hazardous for handling. Hence circulate TEG by the Glycol circulation pumps through Glycol Cooler. Bring down the temperature below 60C and transfer to storage. Drain liquid from vessels to TEG Drain drum and pump to storage. Rounds Equipment

Location

Vent Gas KO Drum 305-V-003 Nitrogen Storage Receiver 324-V-001 Wet Air Receiver 325V-001 Instrument Air Receiver 325-V-002 Heat tracing

TEG Regeneration

Time Sequence 2x per shift

Action

Nitrogen Unit

2x per shift

Instrument Air System

2x per shift

Instrument Air System

2x per shift

Monitor the level and liquid trap base operation Monitor the level

GGS Unit

1x per shift

Monitor the local panel

Monitor the level and liquid trap base operation Monitor the level




SECTION V GAS GATHERING STATION



1.0

INTRODUCTION



1.1



OVERVIEW OF GAS GATHERING STATION

The multiphase fluid from each of the seven Production Well heads in the Ash-Shaer area is transported to a Production Manifold. From the Production Manifold, the multiphase fluid is transported to Production Separator in the Gas Gathering Station (GGS). The Production Separator is a three-phase Separator Vessel where the gas, condensate and water are separated. In the Early Production Phase i.e., at the beginning of the Reservoir production, the well head pressure is high enough to transport the gases from the well head to the Gas Treatment Plant (GTP) through the GGS and Trunk lines. At the later stage of gas production when the Well head pressure comes down, the Field Gas Compressor is used to boost the pressure. In the early production phase, the differential pressure required is low and hence Early-operation Condensate Pumps will be in operation. Later, when the Well head pressure drops, the Field Gas Compressor is operated and Early-operation Condensate Pumps will be taken out of service and Condensate Pumps will take over. The gas from the Production Separator is routed to Gas Dehydration Column where water is removed by using lean Tri-Ethylene Glycol (TEG). The rich TEG generated in the Gas Dehydration Column is regenerated in TEG Regeneration System and returned to the Gas Dehydration Column as lean TEG. The condensate and water are separated in the Production Separator by a weir arrangement. The condensate is pumped by Condensate Pumps to a Condensate Solid Filter and Condensate Coalescer where the fine particles and fine water droplets are removed from the condensate. Finally, the dehydrated gas and condensate are mixed together and transported through a 76 km trunk line to the Gas Treatment Plant (GTP). GTP can be monitored from GGS control room, but no control of GTP is possible from GGS, whereas GGS data can be monitored and controlled from GTP control room.



2.0

SPECIFIC SAFETY HAZARDS



2.1



GENERAL SAFETY PRECAUTIONS AND OPERATIONS

The safety systems in Ebla Project facilities are designed to protect personnel, environment and assets from the threats of production hazards. A minimum risk level is achieved by adopting the following safety aspects: o

Avoiding exposure to potential hazards during operations

o

Minimising the potential (frequency) for hazardous occurrences (release of hydrocarbons, hydrocarbon flammable gases and any other abnormal hazardous events)

o

Containing and minimising the consequence of the hazards (fire, explosion and toxic gas releases)

o

Providing the means of escape and evacuation from such hazards

o

Proving a safe working environment for Plant personnel

As the condensate and gas are sweet, there is no hydrogen sulphide (H2S) hazard involved, however all systems are designed for a H2S concentration of 100 ppm. ENTRY INTO CONFINED SPACE Hazop Action No. 372 Confined space entry shall be as per company PTW procedure. It may be required to inspect the vessel internals or repair a vessel/drum or Closed Drain Drum boot. After draining the vessel and purging with N2, it should be dampened by water source to avoid any fire due to pyrophoric iron deposits. Also purge it for sufficient time such that the vessel is free from H2S/hydrocarbon content before vessel entry. There should not be any traces of H2S in the vessel before vessel entry. Proper PPEs should be used for vessel entry against H2S/Hydrocarbon presence. Refer section 2.3 for details HAZARDS OF H2S 

H2S can be absorbed into the body by inhalation.



H2S is irritating to the eyes and the respiratory tract; it causes unconsciousness or even death at higher concentrations. At 100 ppm, it causes coughing and loss of sense of smell; at 500 - 700 ppm exposures, it will lead to unconsciousness and death in 30 to 60 minutes. At 1000 ppm, it causes rapid unconsciousness; breathing is stopped, resulting in death.






It is colourless with a characteristic smell of rotten eggs. It is heavier than air, hence may accumulate in low areas and travel a considerable distance to a source of ignition.



Occupational Exposure Limits: It has a Threshold Limit Value (TLV) of 10 ppm.

When breaking into a process system that contains gas and condensate, it is necessary to take special precautions as follows: o

Area around the specific area is taped off to prevent personnel approaching the worksite

o Personnel carrying out this operation shall take Work Permit, be aware of the hazards associated with nitrogen (N2), Carbon di-oxide (CO2) and H2S and wear appropriate Personal Protective Equipment (PPE)

o As far as possible, the system to be entered is purged using N 2/water dampening prior to opening. This also negates the threat of elemental sulphur and associated corrosion and cracking. o

Hazop Action No. 30 Special precautions need to be taken on Vessels like Production Separator prior to releasing them to Maintenance/Turnaround Inspection. Even though H 2S content is less than 100 ppm there will be considerable accumulation of pyrophoric scale over a prolonged period of operation. The pyrophoric dust will catch fire when it is exposed to atmosphere. Before opening the Vessel, the Separator shall be dampened from a water source. Disposal of the pyrophoric dust/scale shall be as per Company procedure for disposal of hazardous waste and shall not be dumped in Plant areas which will lead to fire accidents. Pyrophoric fire prevention measures are to be put in place (including availability of relevant portable fire extinguishers)

o

Hazop Action No. 67 Handling and disposal of Contaminated filter Cartridges / Coalescer elements should be done in a safe manner. As these filters contain hazardous sulphur and nitrogen compounds this should be collected and disposed in designated storage areas. Proper PPEs as given in Section 2.3 and precautions to all personnel involved in handling the contaminated equipments to waste storage area.

HAZARDS OF RADIOACTIVE MATERIAL 

Hazop Action No. 31


When

00180-PCP-300-PDMan-12503-01 GGS Operating Manual Vol #1 releasing

Condensate/Produced

Water

Operations Page 37 of 275 Storage

tanks,

Condensate

pumps/Filters, proper safety precautions are to be taken as per PTW Procedures and for vessel entry by Personnel. Check for Oxygen/Toxic HC components. The vessels are damped from a water source to avoid pyrophoric iron fires. Naturally Occurring Radioactive Material (NORM) and Low Specific Activity (LSA) Scale can appear during the drilling and process phases of Oil and Gas exploration and tend to deposit along with other scale. Low Specific Activity scale (LSA) which are found adhering to pipe and equipment internals produce potential radiation illness mainly due to Radium-226 produced from the decay of naturally occurring Uranium-238. Hence Radioactive Detection and PPEs for protection against potential radiation illness should be used. The waste removed from Condensate storage/Produced water storage tanks/cartridge filter should be disposed off at locations specifically marked/designated as Waste holdup/storage area. The Waste disposal area shall be clearly fenced, marked and identified with safety tags/boards indicating warnings/dangers due to radioactive substances. 

Personnel involved in the operation should wear Breathing Apparatus (BA) sets



Flange is broken and hydrocarbon concentration measured



Purging using N2 continues, as necessary



When hydrocarbon concentration drops below 10 ppm, the ‘All Clear’ is given and normal work activities can recommence

2.2

HAZARDS IN HANDLING CHEMICALS

The GGS involves methanol injection and corrosion inhibitor facilities. The Gas Dehydration handles TEG as absorbent chemical for removing the moisture and uses antifoam compounds for avoiding foaming in the Gas Dehydration Column. 2.2.1 Physical and Chemical Properties of TEG TEG is a clear colourless liquid and highly miscible in water with a boiling point of 285C (545F). In case of leak, isolate the area. Keep away unnecessary and unprotected personnel from entering inside the area. Recover liquid wherever possible and collect liquid in an appropriate container or absorb with an inert material (e.g. vermiculite, dry sand and earth) and place in a chemical waste container. Do not use combustible materials, such as saw dust. Do not flush to sewer. Emergency and First Aid Skin Contact




In case of contact, immediately flush the skin with plenty of water for at least 15 minutes. Remove contaminated clothing and shoes. Wash clothing before reuse. Eye Contact If splash occurs, immediately flush the eyes with water for at least 15 minutes, lifting upper and lower eyelids occasionally. 2.2.2 Physical and Chemical Properties of Methanol Methanol is a clear colourless liquid with a characteristic pungent odour; it is miscible in water with a boiling point of 65C (149F). TLV (Threshold limit value)

: 200 ppm

STEL (Short term Exposure limit)

: 250 ppm

In case of leak, isolate the area. Keep unnecessary and unprotected personnel from entering. Contain and recover liquid when possible. Collect liquid in an appropriate container or absorb with an inert material (e.g. vermiculite, dry sand and earth) and place in a chemical waste container. Do not use combustible materials, such as saw dust. Do not flush to sewer. Effects of Over-Exposure 

Inhalation and ingestion are harmful and may be fatal



Inhalation may cause headache, nausea, vomiting, dizziness, lower blood pressure and depression of central nervous depression



Acute ingestion may cause blindness, vomiting, headaches, dizziness and gastro-intestinal irritation



Chronic effects include kidney and liver damage

Emergency and First Aid Skin Contact In case of contact, immediately flush the skin with plenty of water for at least 15 minutes. Remove contaminated clothing and shoes. Wash clothing before reuse. Eye Contact If splash occurs, immediately flush the eyes with water for at least 15 minutes, lifting upper and lower eyelids occasionally. 2.2.3 Physical and Chemical Properties of Sodium Hypochlorite Sodium Hypochlorite is a colourless to yellow green liquid with a chlorine like odour; it is miscible in water and decomposes above 1100C (230F). TLV (Threshold limit value)

: 1 ppm

Do not allow spilled material to enter sewers or streams. Flush with water to dilute as much as possible and pump into polyethylene containers for disposal. Avoid heat and contamination with acid materials. Do not use combustible materials such as saw dust




to absorb hypochlorite. Aquatic toxicity not established, but bleach, if not diluted may seriously affect aquatic life. Emergency and First Aid Eye Contact If splash occurs on eyes, flush with plenty of water for atleast 15 minutes. Get prompt medical attention immediately. Skin Contact In case of contact, immediately flush the skin with plenty of soap and water. If swallowed drink large quantity of milk or gelatine solution. If these are not available drink large quantity of water. Do not give vinegar or other acids. Do not induce vomiting. Get prompt medical attention. 2.3

PPE REQUIREMENTS

Skin Protection Wear protective impervious gloves such as rubber, neoprene or vinyl with rubber safety shoes and body-covering clean clothing. Eye Protection Use chemical safety goggles plus full face shield to protect against splashing (For Sodium Hypochlorite). Maintain eye-wash fountain and quick-drench facilities in work area. Fire Extinguishing Media Keep on hand water spray, dry chemical, alcohol foam, or carbon dioxide extinguishers. Water or foam may cause frothing. Special Information In the event of fire, wear full protective clothing and Self-Contained Breathing Apparatus (SCBA) with full face-piece, operated in pressure-demand mode or other positive pressure mode.



3.0

EQUIPMENT SPECIFICATION





3.1 METHANOL STORAGE TANK Equipment Tag No. Type Process Medium Description Design Temperature Design Pressure Operating Temperature Operating Pressure Operating Capacity Density at WPT Dimension Material of Construction 3.2

Minimum 82.0 –2.5 45.0

20.0 55.0 800 4100 ID x 5000H Shell/Bottom: Carbon Steel Internals: SS 316L

Unit ºC mbarg ºC mbarg m3 kg/m3 mm

METHANOL LOADING/UNLOADING PUMP

Equipment Tag No. Type Fluid Description Temperature (Min/Max) Suction Pressure (Min/Max) Discharge Pressure Flow Density of Liquid at WPT Viscosity of Liquid at WPT Power Material of Construction

3.3

329-T-001 Tank Methanol Maximum –15.0 180.0 –15.0

329-P-001A/S Centrifugal Methanol Rated –15.0/45.0 –0.012/0.59 1.20 20.0 800 0.7 3.7 Casing: CS; Impeller: CS

Unit ºC bara bara m³/h kg/m³ Cp kW

OPEN DRAIN NON-CONTAMINATED SUMP PUMP

Equipment Tag No. Type Fluid Description Temperature Suction Pressure Discharge Pressure Flow Density of Liquid at WPT Viscosity of Liquid at WPT Power Absorbed at Shaft Material of Construction

332-P-001 A/S Centrifugal Water Rated Min 4.0/Max 45.0 0.152 3.7 50 997 0.9 9.6 Casing: SS 316 L;

Unit ºC barg barg m³/h kg/m³ Cp kW



Equipment Tag No. 3.4

Material of Construction

332-P-001 A/S Impeller: SS 316 L

332-P-002 A/S Vertical Centrifugal Pump Water with oil Rated Min 4.0/Max 45.0 0.152 2.3 5.0 1000 0.9 3.7 Casing: SS 316 L; Impeller: SS 316 L


CLOSED DRAIN DRUM

Equipment Tag No. Type Process Medium Description Design Temperature Design Pressure Operating Temperature Operating Pressure Liquid-Rated flow Density at WPT Material of Construction Dimensions 3.6

Page 42 of 275

OPEN DRAIN CONTAMINATED SUMP PUMP

Equipment Tag No. Type Fluid Description Temperature Suction Pressure Discharge Pressure Flow Density of Liquid at WPT Viscosity of Liquid at WPT Power Absorbed at Shaft

3.5

Operations

333-V-001 Drum -Horizontal Hydrocarbon Gas & Condensate Maximum Minimum –15.0 82.0 5.0 FV 4.0 45.0 0.1 5.0 Condensate - 600/Water - 1000 Shell: CS; Boot Cladding: SS316L 2500 ID X 9000 TT

Unit ºC barg ºC barg kg/h Kg/m3

mm

CLOSED DRAIN DRUM HEATER

Equipment Tag No. Type Process Medium Description Design Temperature Design Pressure Operating Temperature Operating Pressure Density at WPT Material of Construction

333-H-001 Electrical Condensate Maximum –15.0 3.5 –4.0

Minimum 82.0 — 4.0 0.1 600 SS 316L

Unit ºC barg ºC barg kg/m3


3.7


Page 43 of 275

CLOSED DRAIN DRUM PUMP

Equipment Tag No. Type Fluid Description Temperature Suction Pressure Discharge Pressure Flow Density of Liquid at WPT Viscosity of Liquid at WPT Motor Power Material of Construction

3.8

Operations

333-P-001A/B Vertical Centrifugal Hydrocarbon Drains Rated 45 3.66 1.94 5 700 0.47 4.12 Casing: SS316L; Impeller: SS316L


LP PRODUCED WATER DISPOSAL PUMP

Equipment Tag No. Type Fluid Description Temperature Suction Pressure Discharge Pressure Flow Density of Liquid at WPT Viscosity of Liquid at WPT Motor Power Material of Construction

334-P-001 A/S Centrifugal Produced Water Rated 45 1.27 5.2 25.5 1200 1.1 11.96 Casing: CS; Impeller: 12% Cr CS





4.0 PROCESS AND CONTROL DESCRIPTION


4.1



PRODUCTION SEPARATOR

The Production Separator is a horizontal three-phase separator vessel where the gas, condensate and water are separated. Equipment Specification Equipment Tag No. Type Process Medium Description Design Temperature Design Pressure Operating Temperature Operating Pressure Liquid Quantity (Condensate/Water) Density at Working Pressure & Temp. (WPT) (Condensate/Water) Vapour Quantity Molecular Weight Density at WPT Material of Construction Dimensions

ID Length (T/T)

302-V-001 Three Phase Separator Vessel– Horizontal Hydrocarbon Condensate, Gas & Water Maximum Minimum Unit 82.0 –15.0 ºC 95.2 — barg (kPa) 41.0 7.7 ºC 86.64 25.39 barg (kPa) 14503/38386

kg/h

554.03/956.48

kg/m3

97980 19.28 20.66 Shell: Killed Carbon Steel (KCS) Internals: Duplex Stainless Steel Cladding: Incoloy 825 2700 12800

kg/h kg/kg mole kg/m3

mm mm

4.1.1 Principle of Separation of Water from Oil in Separators The function of a separator is to remove free gas from condensate and water at a specific pressure and temperature. The Production Separator in the GGS is designed to meet the following requirements: o

Liquid must be separated from gas in a primary separating section

o

Gas velocity must be lowered to allow liquids to drop out

o

Gas must be scrubbed through an efficient demister

o

Water and oil must be diverted to a turbulence-free section of the vessel

o

Liquids must be retained in the vessel long enough to allow separation

o

The water–oil interface must be maintained

o

Water and oil must be removed from the vessel at their respective outlets

The basic principle of separation of water from condensate in the separators is by settling of the heavier phase (water) under gravitational force. In a mixture of immiscible liquids, the heavier phase travels downwards and the lighter phase travels upwards. Density of water droplets is higher than the density of condensate




(continuous phase). Due to this difference in densities, water droplets will travel downwards under gravitational forces. The higher the size of water droplets, the faster will be the speed of downward movement. Similarly condensate droplets in water phase will travel upwards due to buoyancy forces. This separation of oil and water (free water) phases by gravitational forces due to density difference is called as Gravity Settling. Bulk of the water in the condensate is easily separated as it enters the separators. A typical schematic sketch of Three Phase Separator is illustrated in Fig. 1 as given below. Schematic of Three-Phase Separator

The condensate and the water phase are separated in a Weir Plate and the separated condensate flows over the Weir Plate and collects in the Condensate Compartment. A 600 mm internal Baffle Plate is provided at 3000 mm from the inlet nozzle end of the vessel and at a height of 1000 mm from the bottom of the Separator. This Baffle Plate is required to alleviate separation when slug arrives. The separated gas exits through the top outlet nozzle provided with a Mist Eliminator arrangement capable of separating liquid particles larger than 10 micron size. The Production Separator is maintained at a pressure of 87 barg during the HP phase and 36 barg during the LP phase. ESD valve 302-XV-1104 at Production Separator will depressurize to the Flare Header when ESD Level-1 shutdown is activated. The Safety Valves 302-PSV-100A/302-PSV-100B, is set at 95.2 barg and will open to the Flare Header. The Condensate level is controlled by Level Controller and 302-LIC-1119 controls the Interface level.




4.1.2 Production Separator Controls 4.1.2.1

Production Separator Pressure Control (HP Mode)

The Production Separator (302-V-001) pressure is linked to the operating pressure of the Gas Dehydration Column Pressure Controller 305-PIC-3009. This maintains backpressure at the Production Separator. However the excess pressure at Production Separator is controlled by Pressure Controller 302-PIC-1137 which relieves the excess pressure to Flare Header. To avoid flaring due to excessive pressure, Choke Valve can be throttled to reduce pressure at Production Separator. Schematic Sketch of production separator and Condensate system is enclosed in Fig. 2 as given below:




Fig. 2 – Production Separator and Condensate System Controls


4.1.2.2



Condensate Level Control

The condensate level is measured by a Level Indicating Controller 302-LIC-1119 which is a master controller cascaded with the Condensate Flow Controller 302-FIC-1182. Early Operation (HP) Mode During the HP mode, the Condensate Level Controller 302-LIC-1119A which takes the same measurement as 302-LIC-1119 controls the Production Separator level by operating the Recirculation Valve (302-LV-1119) of Early Operation Condensate Pumps (302-P-002A/B). 302-LV-1119 will open in case the condensate level is decreasing below the set point. 302-LIC-1119A shall be forced to Manual mode and output driven to 0% under the following conditions: 

Plant in Normal Operation (LP mode)



Both Condensate Pumps 302-P-002A/B are stopped

Normal Operation (LP) Mode During the LP mode, the Condensate Pumps are protected against low flow by the minimum flow control valve 302-FV-1130. The condensate recycle flow control valve 302-FV-1130 is controlled by 302-FIC-1130 on the Condensate Pumps (302-P-001A/B) discharge line. 302-FV-1130 tends to open in case of condensate flow is decreasing below the set point which is set at Minimum flow of the Pump. 302-FIC-1130 shall be forced to Manual mode and output driven to 0% under the following conditions: 

Plant in Early Operation (HP mode)



Both Condensate Pumps 302-P-001A/B are stopped

Dry Condensate to Export – Flow Control 302-FIC-1182 controls the dry condensate to export flow by throttling the control valve 302-FV-1182 on the dry condensate Export Trunk line. 302-FV-1182 tends to open in case of dry condensate flow increasing above the set point. Override: Dry condensate flow control will be overridden by ‘Low’ condensate pump discharge pressure 302-PIC-1132. This shall be achieved by using a ‘Low signal selector’ block, which will select the lower of 302-FIC-1182 and 302-PIC-1132. The selected controller output will act on 302-FV-1182. The condensate level is monitored by Level Alarms (High High and Low Low) by 302-LAHH-1117 and 302-LALL-1117 respectively. For details, refer Cause & Effect Diagram 250-EPR-CNE-05001. 4.1.2.3

Condensate-Water Interphase Level Control

The condensate-water interface level is controlled by Interface Level Controller 302-LIC-1114 which actuates Produced Water flow to Produced Water Degassing Drum (334-V-001) by level control valve 302-LV-1114. The interface level is monitored by




Level Alarms (High-High and Low-Low) 302-LAHH-1116 and 302-LALL-1116 respectively. For details, refer Cause & Effect Diagram 250-EPR-CNE-05001. 4.2

FIELD GAS COMPRESSOR

During the initial HP phase, the Well head gas pressure is adequate to meet the GTP operating pressure. However, during later phase of operation (LP mode) of wells, the Well head pressure will be low and hence it requires a Field Gas Compressor to boost the pressure. During the HP phase, the entire Compressor circuit is kept in bypass condition. The gas flow joins the inlet of the Gas Dehydration Column (305-C-001). FIELD GAS COMPRESSOR SUCTION KNOCK-OUT DRUM Equipment Tag No. Type Process Medium Description Design Temperature Design Pressure Operating Temperature Operating Pressure Liquid Quantity Density at WPT Vapour Quantity Molecular Weight Density at WPT Material of Construction Dimensions

ID Length (T/T)

304-V-001A/B Vessel– Vertical Hydrocarbon Gas Maximum Minimum 110.0 –15.0 95.2 — 41 7.4 86.04 24.8 24.1 717.04 107623 19.28 20.3 Shell: KCS, Clad with SS 316L; Internals: SS 316L 2700 4400

Unit ºC barg (kPa) ºC barg (kPa) kg/s kg/m3 kg/h kg/m3

mm mm

FIELD GAS COMPRESSOR Equipment Tag No. Type Fluid Description Suction Temperature Suction pressure Discharge Temperature Discharge Pressure Flow Molecular Weight Power Material of Construction

304-K-001A/B Centrifugal Wet Hydrocarbon Gas Rated 35.5 24.9 166.3 87.5 97839 19.28 9080 Casing: Duplex Stainless Steel Impeller: Duplex Stainless Steel

Unit ºC bara ºC bara kg/h kW




FIELD GAS COMPRESSOR AFTERCOOLER Equipment Tag No. Type Fluid Description Design Temperature – Tube Working Temperature – Tube Design Pressure – Tube Working Pressure – Tube Fluid – Tube Heat Duty Air Design Temperature No. of Fans Material of Construction Coolant

304-E-001A/B Air Cooler & Forced Draft Tube: Wet Hydrocarbon Vapour Maximum Rated — 192 Inlet: 166.2 Outlet: 50.1 — 95.2 Inlet: 87.5 Outlet: 86.8 97839 8254.7 + 10% margin 45 Max.; –15 Min. 4 Tube: SS 316 L + Aluminium fins Air

Unit ºC ºC bara bara kg/h kW ºC No.

4.2.1 Process Description During the LP phase, the gases from the top outlet of the Production Separator (302-V-001) reach the Field Gas Compressor Suction KO Drum (304-V-001A). There are two streams of Compressor Systems; one on duty and the other on standby in parallel mode. The split streams for the two compressor systems are identical, with a Suction Knock-Out Drum, Compressor and Compressor After cooler arrangement. The gas stream enters the Compressor Suction KO Drum-A (304-V-001A) through an ESD Valve 304-XV-1200 provided with an ESD Bypass Valve 304-XV-1201. ESD Valve 304-XV-1200 will open only if the differential pressure (304-PDI-1206) is below 2.5 barg. The Compressor Suction KO Drum consists of Vane-type Inlet Distributor through which the gas enters. The entrained condensate is separated and further fine droplets of condensate (more than 3 micron) are removed in the Demister Pad located at the gas outlet on the KO Drum top. The demister can remove 99% of the particles larger than 3 micron size. The Compressor KOD 304-V-001A is provided with two PSVs 304-PSV-110A and 304-PSV-110B which is set at a pressure of 95.2 barg. The condensate level in the Compressor Suction KOD is controlled by 304-LIC-1210. The Controller acts on Control Valve 304-LV-1210 to control the condensate flow to Flare Header. The Level Transmitter 304-LT-1209 has High-High and Low-Low level alarms 304-LAHH-1209 and 304-LALL-1209 respectively. For details, refer Cause & Effect Diagram 250-EPR-CNE0500. The gas from 304-V-001A enters the suction side of the Field Gas Compressor 304-K-001A. The suction pipe of 304-K-001A is provided with a temporary hose connection for nitrogen purging, during the start-up period. The suction pressure of the compressor is controlled by a self-regulating Pressure Control Valve 304-PCV-1294 which vents gas to Flare during the pressurized shutdown. Set pressure of 304-PCV-1294 above the settle out pressure. This PCV will be used to maintain pressure in the system during pressurized shutdown of the Compressor and not during normal operation. The compressor suction pressure is controlled by the Variable Speed Drive. The suction-side gas flow, temperature and pressure are




measured by 304-FI-1220, 304-TI-1222 and 304-PI-1221 which is also used for the anti-surge control of the compressor. Similarly the discharge pressure and temperature of the Compressor is indicated by 304-PI-1232 and 304-TI-1231 respectively. The compressed gas from the compressor discharge at a pressure of 87.5 barg and temperature of 166°C flows to the Field Gas Compressor Aftercooler-A (304-E-001A) where the temperature is cooled to 50C by Fin Fan Coolers. The compressed gas temperature is controlled by using 304-TIC-1215 which will control the Variable Speed Drive of the Fin Fan Motors. From the outlet of the Fin Fan Coolers, the gas is recycled to the suction of KO Drum 304-V-001A by the Antisurge Controller to minimise the surge. The compressed gas flows to the Gas Dehydration column through an ESD valve 304-XV-1219.

4.2.1.1

Compressor Auxiliary System

The Field Gas Compressor has two main auxiliary units – the Lube Oil system and the Seal Gas system. Auxiliary Lube Oil System The Lube Oil system comprises the following: Lube Oil Reservoir (304-T-1500), Lube Oil Heater (304-H-001A), Auxiliary Lube Oil Pump (304-P-002A), Main Lube Oil Gear Pump, Lube Oil Cooler (304-E-002A) and Lube Oil Filters 304-F-001A1/A2. During normal operation, the lube oil is supplied by the gear-driven main pump. The Auxiliary Lube Oil Pump is used during start-up, shutdown and also as a standby pump to main oil pump when the oil pressure is not adequate. The Lube Oil Reservoir level and temperature are indicated by Level Indicator 304-LI-1505 and Temperature Indicator 304-TI-1514 respectively. The Reservoir temperature is maintained by an




electric Heater which maintains the lube oil in the reservoir at a constant temperature. The temperature indicator 304-TI-1514 and level indicator 304-LI-1505 are provided with High and Low level alarms. The lube oil from the discharge of the Auxiliary/Main Lube oil pump is cooled in Lube Oil Coolers (304-E-002A) which are Air Fin Coolers. The lube oil header pressure is maintained at 2.5 barg by a Pressure Control Valve 304-PCV-1510 by regulating the lube oil back to the Lube Oil Reservoir. The lube oil is then filtered by Lube Oil Filters (304-F-001A1/A2) and distributed to the Motor and the Compressor (DE & NDE). The lube oil is supplied to the following items: o

Motor Bearings

o

Gearbox

o

Compressor (DE & NDE) bearings

The return lube oil flows to the lube oil reservoir through restriction orifices.




Seal Gas System The Seal Gas provides the sealing media to the compressor seals. The dry gas seals consist of an inboard seal and an outboard seal. The inboard-seal seals between the process gas pressure inside the compressor and the pressure in the primary vent line. The outboard-seal seals between the primary and secondary vent line pressures. A schematic sketch of the Compressor Seal gas system is illustrated in Fig. 3 as given below: Fig. 3 – Schematic of Compressor Seal System

The primary seal gas from the discharge of the Compressor is filtered at the Seal Gas Filters 304-F-002A1/304-F-002A2. During Normal operation of the Compressor, Seal Gas is supplied from the Compressor Discharge. However, during the Start-up condition and Black-Start condition, bottled nitrogen will be used for the dry gas seal. In case of pressurized shutdown, the Settle-out Pressure is 46.4 barg. During this period, the seal gas supply can be supplied from the HP Fuel Gas tapped from the downstream (D/S) of Fuel Gas Heater (321-H-001A/B) to ensure dry heated gas supply to Dry Gas Seals. The suction pressure of the compressor is controlled by a self-regulating Pressure Control Valve 304-PCV-1294 whose set pressure is above the settle out pressure. This PCV will be used to maintain pressure in the system during pressurized shutdown of the Compressor and not during normal operation.




Similarly, the Secondary Seal Gas is nitrogen gas, filtered in Buffer Gas Filters 304-F-003A1/A2. The Nitrogen (from Utilities) from the Buffer Gas Filters is split into two lines - one supplying as secondary seal gas through 304-PV-1465 and the other supplying seal gas through 304-PV-1449 for bearing separation seal. The leaking gas from the primary and secondary seal is vented to the Flare Header under Backpressure Controller 304-PCV-1464. The seal vent between the secondary seal and bearing separation seal is vented to the atmosphere at a safe location. 4.2.2 Field Gas Compressor Controls All control and safeguarding functions of the Field Gas Compressor and its auxiliaries will be controlled by Unit Control Panel (UCP) based control system, which consists mainly of PLC, Vibration and Displacement monitoring system and Human Machine Interface (HMI). All functions like the compressor start-up and shutdown sequence, anti-surge control, performance control, control and safeguarding of lube oil system, seal gas system, separation gas system, compressor bearings, motor bearings/purge unit/stator windings/cooling system, and, vibration and displacement monitoring system will be executed in the UCP. The compressor control system has interface with the plant DCS and ESD systems for monitoring, alarming and safe operation. It will also perform operations like Start-up sequence initiation, emergency stop, and manual operation of lube oil pumps and coolers from DCS. The various controls of Field Gas Compressor below relate to Compressor Train-A. Train-B is similar to Train-A, and hence not described separately. During Early Plant (HP) operation, all motor blocks and controllers related to Suction KO Drums, Compressors and After-coolers shall be disabled. Feed Gas Compressor Anti-Surge Control The anti-surge controller resides in the UCP. The process variable inputs to the antisurge controller and their related alarms will be conveyed to DCS over the serial link. The anti-surge control algorithm determines the compressor operating point relative to the surge limit/anti-surge control line, based on the following process variable inputs: o

Static pressure at the inlet and outlet of compressor: 304-PT-1221 and 304-PT-1232

o

Temperature at the inlet and outlet of compressor: 304-TT-1222 and 304-TT-1231

o

Flow into the compressor: 304-FT-1220

When the compressor approaches the anti-surge control line, the anti-surge controller will open the Anti-Surge Valve 304-FV-1212, located on the compressor recycle line, to prevent surge. When the compressor is running and well above the surge control line, the anti-surge valve is closed. The various modes of the anti-surge controller are listed below: o

In normal operation, the anti-surge controller is in AUTO


o



During compressor start-up and shutdown sequence, the controller is forced in ‘SEQUENCE’ and the anti-surge valve opens

o

The anti-surge controller can be manually operated to open or close the anti-surge valve from the UCP HMI (Human-Machine Interface). However, if the compressor operating point approaches the anti-surge control line, the controller is switched back to Auto mode automatically.

Performance Control – Suction Pressure Controller The compressor performance is controlled by the Compressor Suction Pressure Controller. Compressor suction pressure is measured by 304-PT-1221. The suction pressure controller sends a speed set-point signal to the Variable Speed Drive System (VSDS). Speed variation up to 80% is only possible. The Performance Controller is present in the UCP and can be operated when in Local mode. However the Performance Controller can also be operated from DCS when selector is in Remote mode. For Compressor discharge pressure limiting, a discharge pressure Over-ride Controller is provided. If the Compressor discharge pressure increases above its set point, the Discharge Pressure Over-ride Controller over-rides the Suction Pressure controller when the output of the Over-ride Controller is below the output of the Suction Pressure Controller. The set point of the over-ride controller is fixed and written in the PLC (UCP). However the set point for the Suction Pressure Controller can be adjusted from the UCP HMI as well as from the DCS panel depending on the position of the Local/Remote switch. When the switch is in ‘Remote’ position, following operations from DCS is possible: o

DCS set point is written to the Controller (DCS shall ‘track’ the controller set point when in ‘local’). The controller shall send the set point, as an analog value, back to the DCS for display of ‘set point’ on the DCS Controller faceplate.

o

Controller can be switched from AUTO to MANUAL, by sending a pulsed command from DCS to UCP. The controller shall send a confirmatory pulse back to the DCS for display of ‘AUTO/MANUAL’ on the DCS faceplate.

o

In MANUAL, the output of the valve can be manipulated from the DCS. The DCS requested valve position, which is an analog signal, is written to the controller.




The controller shall send the valve position, as an analog value, back to the DCS for display of ‘valve position’ on the DCS faceplate. The VSDS tends to decrease the speed of the compressor in case the suction pressure is decreasing below the set point. The various modes of the Compressor Suction Pressure Controller are listed below: o

In normal operation, the suction pressure controller is in Auto, the discharge pressure over-ride controller shall be in Track.

o

During Compressor start-up and shutdown sequence, the Suction Pressure Controller is forced in ‘SEQUENCE’.

o

The Suction Pressure Controller can be manually operated to increase or decrease the compressor speed from the UCP HMI and the DCS. However, switching from Auto to Manual is only possible when the controller is in Auto and not in Track.

Compressor Lube Oil System All control, safeguarding, start-up and shutdown sequence concerning the compressor lube oil system is implemented in UCP. However lube oil coolers and pumps can be started and stopped from the DCS. The lube oil reservoir temperature is controlled by an electric heater with thermostat switch. The Lube Oil Reservoir temperature is controlled by 304-TC-1527 which controls the heater by a thermister control which switches the heater ON and OFF at a desired temperature. The lube oil header temperature is maintained at 59°C by a temperature controller acting on a Three-Way Valve 304-TCV-1503 which bypasses the lube oil across the Lube Oil Cooler (304-E-002A). The lube oil supply pressure is controlled by self-actuated Pressure Control Valve 304-PCV-1510 which maintains the header pressure at 2.5 barg by opening to the Lube Oil Reservoir. At start-up, the Lube Oil Cooler Fans need to be started before the Lube Oil Pump. A minimum of two fans shall be started. This can be done from the UCP HMI as well as from the DCS. Before the standby lube oil pump can be started, the lube oil temperature shall be above 10C and the separation gas shall be applied. The start-up permissive are built in the PLC (UCP). The Standby Lube Oil Pump is automatically stopped after the gear-driven main pump is running and maintains the header pressure above 2.5 barg. Seal Gas and Separation Gas System The dry gas seal consists of an inboard and an outboard seals. The inboard-seal seals between the process gas pressure inside the compressor and the pressure in the primary vent line. The outboard-seal seals between the primary and secondary vent line pressures. The primary vent pressure is controlled such that there is always some flow through the inboard seal and the outboard seal for cooling purposes. 304-PIC-1464 controls the primary vent pressure by throttling the Control Valve 304-PCV-1464 located on the primary vent to flare system. The secondary seal gas (N2) is supplied at controlled pressure by 304-PIC-1465. The secondary seal gas (N 2) is supplied to the barrier seals to prevent lube oil carry-over to the seal area and vice versa. This is




provided via a self-acting pressure regulator 304-PV-1449. These controllers are integrated in PLC and have no DCS control. The following shutdown conditions of Seal Gas & Lube Oil cause Unit Shutdown with Blowdown:

o

Primary seal vent pressure NDE – Low-Low

o

Primary seal vent pressure NDE – High-High

o

Primary seal vent pressure DE – Low-Low

o

Primary seal vent pressure DE – High-High

o

ESD1 (trip with blowdown)

o

ESD button compressor skid

o

ESD button on UCP (unit control panel)

o

UCP critical failure

However the ESD3 (recycle trip) causes unit shutdown in recycle mode, whereas all other shutdown conditions cause unit shutdown without blowdown. Refer Siemens Cause & Effect diagram (HE612428200) Compressor Sequencing Compressor start-up and shutdown sequence is built in the PLC (UCP). The Start-up sequence can be started in Manual mode in step-by-step sequence or the sequence can be stopped from the DCS. The status of various stages of the sequence shall be displayed in the DCS graphics. During normal operation when the compressor is running, all the controllers are in Auto. Before initiating the start-up sequence, all trips have to be cleared and all the start-up interlocks have to be fulfilled. When all systems are healthy, the compressor will be pressurized. The casing and seal cavity shall be drained before every start-up, which is a manual activity and upon completion, will be conveyed from DCS to the PLC as a pulse command. The compressor is started with an open anti-surge valve. Once the motor is running at minimum speed, the compressor can be loaded; the anti-surge and performance controllers will be switched from SEQUENCE to AUTO. When the compressor is stopped, the anti-surge controller is switched to SEQUENCE, the anti-surge valve is force-opened and the compressor is brought to a standstill in the pressurized state. The motor will stop within a predefined time. ESD trip with or without blowdown shall be as per the conditions given in supplier’s C&E diagram, document no. JI-190-C02411-EMR-D16-002. Also refer C&E diagram 250-EPR-CNE-05001.




Compressor Suction KOD Level Control The level of the collected condensate in 304-V-001A is controlled by a level-indicating Controller 304-LIC-1210 which acts on 304-LV-1210 connected to a Flare Header. The Level Controller works on Gap Control philosophy which opens the Level Control Valve at the high level setting of 304-LIC-1210 and continues to remain open till it reaches the Low level setting of 304-LIC-1210. The valve continues to be in closed condition until the level again reaches the High level set value. Field Gas Compressor Aftercooler Temperature Control Field Gas Compressor Aftercooler 304-E-001A has two bays, each bay comprising of a Variable Speed Drive (VSD) driven fan, a Fixed Speed fan and three sets of Louvers. The outlet temperature is controlled by 304-TIC-1215, which controls the speed of the VSD driven fans and also implements an ‘ON-OFF’ control of the fixed speed fans. During periods of low ambient temperature, fixed speed fans will be automatically turned off to ensure a steady outlet temperature of 50C and the VSD driven fans reach their lowest controllable speed. 304-TICA-1268 and 304-TICA-1275 control the set of louvers of the respective bay. The VSD driven fan speed is controlled by the continuous control from 304-TIC-1215. In case of temperature increasing above the set point, the controller output also increases. 304-TIC-1215 output is simultaneously given to both the VSDs, such that the two fans always run at same speed. The fixed speed fan is controlled as follows. In case 304-TIC-1215 output rises above the high set point (configurable), a ‘START’ command is send to PMS to start both the fan motors simultaneously. The motors continue running till the temperature falls below the low set point (configurable), when the controller sends a ‘STOP’ command to stop both the fan motors simultaneously. The motor remains stopped till the temperature re-attains the high set point and the cycle will continue. Thus, at all times the two fans are either running or stopped. ‘START’ and ‘STOP’ commands are sent from DCS to PMS over serial link. Motor ‘fault’, ‘tripped on ESD’, ‘available/not available’, ‘running/stopped’ and ‘VSD trouble’ (only for VSD drives) feedbacks shall be available to DCS from PMS over serial link. Fixed speed motor can be started or stopped by the operator in ‘Manual’ from the DCS HMI. Auto/Manual logic for the fans resides in CMS. Variable speed motor shall be started by the operator from the DCS, always forced in ‘Manual’. When the ‘START’ command is sent from DCS to VSD, VSD shall start and ramp up to the speed as per 304-TIC-1215 output. The operator can manually modulate the fan speed by switching the controller in ‘Manual’. If the VSD trips from ESD or is stopped from DCS, the controller output is forced to 0% and switches to ‘Manual’ mode. The bay-1 and bay-2 louvers Tilt Angles are controlled by the continuous control from 304-TICA-1268 and 304-TICA-1275 respectively. In case of temperature increasing above the set point, the controller output increases. 304-TICA-1268/75 output is




simultaneously given to all the three louvers, such that the three louvers of the same bay always have the same tilt angle. If temperature at outlet of Air Cooler goes below the set point, first VSD driven fan reduces speed. When it reaches to minimum speed, fixed speed fan is switched off and VSD fan increases up to the requirement. Louver is operated based on intake air temperature controller. The set point of air temperature controller is above hydrate formation temperature and louver control will come only when air temperature drops below the set point value. Early Plant (HP) Operation During this mode, the suction KO Drums, the Field Gas Compressors and their Aftercoolers will be bypassed. Hence, all controllers, as listed below, related to the suction KO Drums, the Field Gas Compressors and the Aftercoolers shall be forced to ‘Manual’ and outputs driven to 0% during HP mode operations. 304-TICA-1268 304-TICA-1275 304-TICA-1215 304-LIC-1210 304-TICA-1368 304-TICA-1375 304-TICA-1315 304-LIC-1310

Field Field Field Field Field Field Field Field

Gas Gas Gas Gas Gas Gas Gas Gas

Compressor Aftercooler-A louver control (bay-1) Compressor Aftercooler-A louver control (bay-2) Compressor Aftercooler-A outlet temperature control Compressor Suction KO Drum-A level control Compressor Aftercooler-B louver control (bay-1) Compressor Aftercooler-B louver control (bay-2) Compressor Aftercooler-B outlet temperature control Compressor Suction KO Drum-B level control

In addition to the above, the compressor faceplate for DCS operations like compressor start sequence, compressor motor start, lube oil standby pump start and lube oil coolers start shall be disabled during HP mode. 4.3

CONDENSATE SYSTEM

4.3.1 PROCESS DESCRIPTION The condensate from the Production Separator (302-V-001) is pumped by Condensate Pumps 302-P-001A or 302-P-001B during the LP Phase operation whereas the Early Operation Condensate Pumps 302-P-002A and 302-P-002B will be in line during the HP phase. During the LP phase, the Minimum-flow Controller 302-FIC-1130 installed on the discharge side of the Condensate Pumps protects the pump by operating the Minimum-flow Controller Valve 302-FV-1130. During HP phase, the Level Controller 302-LIC-1119A controls the Level control valve 302-LV-1119. During normal operation (LP Phase) one condensate pump will be running and Standby pump will start automatically in case the duty pump trips. This protection is provided for both the Condensate Pumps and the Early Operation Condensate Pumps. The condensate from the discharge of the Condensate Pumps flows through Condensate Solid Filters (302-F-001A/B). The Condensate Filters will remove 100% of 25-micron particle size and above, and remove 90% of 20-micron particle size and above. One filter will be on




line and the differential pressure across the filter 302-F-001A is measured by 302-PDI-1146; 302-PDI-1144 measures the differential pressure for 302-F-001B filter. As the differential pressure of the filters increases, alarm will sound and the filter will be isolated and changed to the standby filter. There are two Safety Relief Valves 302-PSV-105 and 302-PSV-106 set at a pressure of 142 barg which opens to the Flare Header. The Condensate from the Condensate Filters flows to the Condensate Coalescer 302-F-002A/B where water from the Condensate is removed. The Coalescer is designed for inlet water content of 1% by volume and the outlet water content should be less than 200 ppm. The Interface levels of Coalescer 302-F-002A/B are measured by Level Transmitters 302-LT-1156A&B respectively. One Coalescer will be on line and the differential pressure across the Coalescer element 302-F-002B is measured by 302-PDI-1168 and 302-PDI-1169 measures the differential pressure for 302-F-002A. At high differential pressure alarm of the Coalescer, the Coalescer will be isolated and changed to the standby Coalescer. There are two Safety Relief Valves 302-PSV-107 and 302-PSV-108 set at a pressure of 142 barg and the blowdown is connected to the Flare Header.




CONDENSATE PUMPS Equipment Tag No. Type Fluid Description Temperature Suction Pressure Discharge Pressure Flow Density of Liquid at WPT Viscosity of Liquid at WPT Motor Power Material of Construction Seal Type

302-P-001A/B Centrifugal Hydrocarbon Condensate Rated 36.0 26.2 95.0 24.5 661 0.33 202 Casing: Duplex Stainless Steel Impeller: Duplex Stainless Steel Mechanical


CONDENSATE COALESCER Equipment Tag No. Type Process Medium Description Design Temperature Design Pressure Operating Temperature Operating Pressure Liquid Quantity Density at WPT Material of Construction

302-F-002A/B Coalescer Vessel Condensate Maximum –28.0 142.0 8.0 87.3 36.7 0.650 Shell: Carbon Steel Cladding: Duplex SS

Minimum 82.0 — 41.1 —

Unit ºC barg ºC barg M3/h Kg/m3

Minimum 82.0 — 41.1

Unit ºC barg ºC barg m3/h kg/m3

CONDENSATE SOLIDS FILTER Equipment Tag No. Type Process Medium Description Design Temperature Design Pressure Operating Temperature Operating Pressure Liquid Quantity Density at WPT Material of Construction

302-F-001A/B Filter – Catridge Condensate Maximum –28.0 142.0 8.0 87.9 36.7 0.650 Shell: Carbon Steel Internals: Duplex SS Cladding: Duplex SS




EARLY OPERATION CONDENSATE PUMPS Equipment Tag No. Type Fluid Description Temperature Suction pressure Discharge pressure Flow Density of Liquid at WPT (Rich Winter/Lean Summer) Viscosity of Liquid at WPT (Rich Winter/Lean Summer) Motor Power Material of Construction Seal Type

302-P-002A/B Rotary Progressive Cavity Type Hydrocarbon Condensate Rated 41 87.4 98.2 36.6

Unit ºC bara bara m³/h

664.5/554

kg/m³

0.18/0.307

Cp

40.56 Casing: Duplex Stainless Steel Impeller: Duplex Stainless Steel Mechanical

kW

4.3.2 Condensate System Control The interface levels of Coalescer 302-F-002A/B are measured and controlled by Transmitters 302-LT-1156A/B respectively. The coalescer LT for duty is selected through a duty/standby selector switch 302-LHS-1156. The Produced Water level is controlled by Level Controller 302-LIC-1156 which controls 302-LV-1156 located on the Produced Water outlet line. The dry condensate from the Condensate Coalescer is injected into the dry gas from the Gas Dehydration Column 305-C-001 and the mixed fluid is routed to GTP through a 76 km trunk line. 4.3.2.1

Normal Operation (LP) Mode

During LP mode, the Condensate pumps are protected against low flow by the Minimum-Flow Control Valve 302-FV-1130 operated by Controller 302-FIC-1130, which shall be forced to ‘Manual’ and output driven to 0% under the following conditions: o

Plant in Early Operation (HP) mode

o

Both condensate pumps 302-P-001 A and B are stopped

4.3.2.2

Early Operation (HP) mode

During HP mode, Production Separator Condensate Level Controller 302-LIC-1119A, which takes the same measurement as 302-LIC-1119, controls the separator level by operating the Level Control Valve 302-LV-1119 at the Condensate Pump (302-P-002A/B)




recycle line. The Early Operation Condensate Pumps are Positive displacement Pumps and works on back pressure. Trunk line operating pressure varies from 68.2 Bara (during turndown operation) to 86.2 bara (during normal Plant Operation). During HP mode of operation, Production Separator pressure is 87.0 bara. Hence during the HP mode of operation, there are chances of operating 302-P-002A/B at very low differential pressure. 302-PIC-1132 will maintain certain differential pressure for 302-P-002A/B by throttling 302-FV-1182 using output from 302-PIC-1132. 302-LIC-1119A shall be forced to Manual mode and output driven to zero under the following conditions: o

Plant in ‘Normal Operation’ (LP) Mode

o

Both condensate pumps 302-P-002A and B are ‘Stopped’

Dry Condensate to Export – Flow Control 302-FIC-1182 controls the dry condensate to export flow by throttling the Control Valve 302-FV-1182 on the dry condensate export line. 302-FV-1182 tends to open in case of dry condensate flow decreasing below the set point. Over-ride: Dry condensate flow control will be overridden by condensate pump discharge pressure 302-PIC-1132. This shall be achieved by using a ‘Low Signal Selector’ block, which will select the lower of 302-FIC-1182 and 302-PIC-1132. The selected controller output will act on 302-FV-1182. 4.3.3 Condensate Coalescer Interface Level Control The Level Selector Switch 302-LHS-1156 selects either of the Condensate Interface level 302-LIC-1156A or 302-LIC-1156B in operation and will control 302-LV-1156 on feed to Produced Water Degassing tank 334-V-001. For details refer Cause and Effect diagram 250-EPR-CNE-05001 4.4

GAS DEHYDRATION SYSTEM

4.4.1 Process Description The solvent used for the removal of water is Tri-Ethylene Glycol (TEG). After absorption of water, the rich TEG is regenerated in TEG Regeneration system and recycled back to the Dehydration Column as Lean TEG. The mass transfer is achieved by a packing column where the lean TEG is counter-currently contacted with wet gas. The wet gas from the Feed Gas Compressor at a pressure of 87 barg and temperature of 50C enters the Gas Dehydration Column (305-C-001). During the HP case, when the Well head pressure is high enough, the Feed Gas Compressor system is totally bypassed and joins the inlet of the Gas Dehydration Column. The wet gas enters the bottom section of the Column. It flows into the Inlet Scrubber section of the Column where any entrained liquid is removed before the gas is introduced into the dehydration section of the contactor. All the liquids (condensate hydrocarbons or liquid water) recovered in the bottom of the inlet scrubber are drawn down under level control and drained to Flare Drum through a Check Valve, ESD Valve 305-XV-3001 and a Level Control Valve 305-LV-3013 during HP mode of operation. During LP operation, the condensate is returned to the Production Separator. There are two Level Transmitters,




one for bottom level control of condensate in the inlet scrubber 305-LT-3013 and the other for ESD control 305-LT-3015. For the effects of 305-LAHH-3015 and 305-LALL-3015, refer Cause & Effect Diagram 250-EPR-CNE-05001. The inlet gas separation device allows a large gas flow turndown while assuring even gas distribution. The gas separation device (vane type) uses curved plates to disperse all inlet gas evenly beneath a wire mesh Mist Eliminator and to separate gas and liquid efficiently. The purpose of the mist eliminator is to coalesce the condensate droplets from the gas stream. The gas then flows through the gas risers of the glycol chimney tray, which allows a uniform distribution of the gas before it enters in the gas/glycol contacting section. The structured packing in the Gas Dehydration Column is to ensure uniform distribution and contact between the liquid and the vapour. There are two level transmitters 305-LT-3017 which control the rich TEG level and 305-LT-3016 for trip purpose. There are High-High and Low-Low level alarms 305-LAHH-3016 and LALL-3016, the effects of which are detailed in Cause & Effect Diagram 250-EPR-CNE-05001. The lean glycol from the discharge of Glycol Circulation Pumps (305-P-003A/B) enters at 55C in order to have a contact temperature of 10C above the wet gas inlet temperature. The lean glycol enters at the top of the column and is equally distributed over the whole section of the column by the Glycol Distributor installed above the packed bed. The dehydration by absorption takes place as the gas flows upwards through the packing, contacting the wetted surface of the packing. A high efficiency Demister removes entrained glycol droplets from the dehydrated gas stream before it leaves the top of the contactor. The dehydrated gas from the top of 305-C-001 enters Dry Gas/Lean TEG Heat Exchanger (305-E-004) where the lean TEG is cooled to maintain the difference of 5 to 10C between the lean TEG and wet gas (entering the dehydration column). The rich TEG comes down the structured packing after absorption of moisture and is sent to TEG Regeneration system. There are two Safety Relief Valves 305-PSV-119A and 305-PSV-119B which are set at a pressure of 95.2 barg provided on the top of 305-C-001 which will release to Flare header during over-pressurization of Dehydration Column. The differential pressure across the packed column is monitored by Differential Pressure Transmitter 305-PDI-3007 and sounds a high differential pressure alarm when the pressure reaches the alarm set point. The higher differential pressure across the contactor indicates foaming in the Contactor. There are high-pressure and low-pressure alarm set points indicated by 305-PAL-3009 and 305-PAH-3009. The flow of dehydrated gas from the outlet of 305-E-004 is measured by 305-FI-3006. At the downstream of ESD Valve 305-XV-3004, the dry condensate from Coalescer and the dehydrated gas are mixed and transferred to GTP through the trunk line. There are methanol injection points ME-711 and ME-713 on the top vapour lines. There is a Moisture Analyzer 304-AI3022 which measures the moisture content of the dehydrated gas. The analyser is provided with High alarm and High-High alarm set at 1.3 lb/MMSCF and 1.5 lb/MMSCF respectively.




GAS DEHYDRATION COLUMN Equipment Tag No. Type Process Medium Description Design Temperature Design Pressure Operating Temperature Operating Pressure Liquid- Flow Density at WPT Vapour Quantity Molecular Weight Density at WPT Structured Packing

Material of Construction

Dimensions: OD Length (T/T)

305-C-001 Packed Column Hydrocarbon Gas & TEG Maximum Minimum Unit 82 –15 ºC 95.2 — barg 12.5 55 ºC 67.2 85.2 barg 6201 kg/h 1100 kg/m3 97980 kg/h 19.28 20.66 kg/m3 4600 mm Top Shell: A516 Gr7 ON Bottom Shell: A516 Gr7ON + 3mm SS-316L Cladding: Internals: A516 Gr 70 Cladding: 3 mm SS-316L Bottom: 1714;Top: 1494 Mm 12600 mm




Fig. 4 – Gas Compression and Gas Dehydration




4.4.2 Gas Dehydration Controls 4.4.2.1

305-C-001 Pressure Control

Under normal operation, the Dehydration Column (305-C-001) pressure is governed by the pressure losses in the downstream trunk line up to the GTP facility. However, to prevent a low pressure occurring in the contactor during low flow or upset conditions, 305-PIC-3009 will control the column pressure by throttling 305-PV-3009A and 305-PV-3009B in split control. Under normal conditions, the Full-Bore Valve 305-PV-3009A on the dry gas line and 305-PV-3009B located in parallel to 305-PV-3009A remain fully open. In case of very low pressure, i.e. when the dry gas pressure falls below the set point, 305-PV-3009A fully closes and the gas is routed via 305-PV-3009B, to elevate the pressure in the gas dehydration column. The minimum pressure to be maintained in dehydration column is 68.2 bara during the turn-around operation. The Split range control valve is illustrated as given below in Fig. 5: Fig. 5 – Split Range Control

During the start-up phase, the pressure is controlled by Pressure Controller 305-PIC-3024 which opens to flare by operating 305-PV-3024 which acts as a spill-off control valve as well to dump gas to the flare system upon detection of high pressure.

4.4.2.2

305-C-001 Rich TEG Level Control

The rich TEG after the absorption of water is routed to TEG Regenerator system by level control. The Rich TEG level is controlled by a Level Controller 305-LIC-3017 which controls 305-LV-3017 to TEG Regenerator system.


4.4.2.3



305-C-001 Bottom Level Control

All the liquids (condensate hydrocarbons or liquid water) recovered in the bottom of the Inlet Scrubber are drawn down under level control and returned to the Production Separator/Flare during LP/HP Mode. 305-LIC-3013 controls the bottom level of the Inlet Scrubber. It is a Gap Controller which has On/Off action on Control Valve 305-LV-3013 through which the knocked out condensate liquid is returned back to the inlet of Production Separator during LP mode operation. During HP mode operation, all liquid recovered in the bottom of dehydration column is routed to flare.

4.5

TEG REGENERATION SYSTEM

4.5.1 Principle of TEG Regeneration System The rich glycol from the Gas Dehydration Column bottom needs regeneration to reclaim its initial characteristics, before its re-use. This is achieved in the TEG regeneration system, where water is separated from the rich glycol by fractionating the rich solution at a high temperature. The rich glycol after absorption of water leaves the contactor on level control. It first flows through the Reflux Condenser in the top of the Regeneration Still Column, thereby providing reflux cooling in the Reflux Condenser. A simplified sketch of TEG Regeneration system is given below in Fig. 6.




Fig. 6 – TEG Regeneration System




The rich glycol is then heated to about 60C or 70C in the Cold Lean/Rich Glycol Heat Exchanger before entering the Glycol Flash Vessel (operating pressure is 4 barg). In this 3-phase separator, dissolved and entrained gases flash off and are removed from the glycol. Liquid hydrocarbon condensate, if present, is also separated from the glycol. If not separated off, these hydrocarbon components would flash in the Regenerator and lead to an increased still-column vapour load, a higher reboiler duty requirement, greater glycol losses and a loss of recoverable product. These components could also lead to coking of the reboiler heating elements, fouling, foaming and a higher BTEX level in the water condensed from the overhead condenser. While this arrangement is typical, in some units the Glycol Flash Vessel is located immediately downstream of the contactor, operating at a lower temperature. From the flash vessel the rich glycol flows through a full flow particle filter and an activated carbon filter often in slipstream service, to remove solids and dissolved hydrocarbons and degradation products, respectively. The rich glycol is further heated in the LP rich/lean glycol heat exchanger and then flows to the regenerator still column where it enters between two contacting sections. Heat is provided at the bottom of the regenerator in order to evaporate water from the glycol. The reboiler may be directly fired or indirectly heated by electricity, hot oil or steam. Typical operating temperatures for TEG are up to 204°C. Water and volatile species present are evaporated from the rich glycol, and reflux is provided to reduce glycol losses. Because of the wide difference in volatility, only a small reflux is needed to effect water/glycol separation. The regenerated hot lean glycol leaves the Reboiler, flows through the stripping column and collects through the TEG surge drum. GLYCOL CIRCULATION PUMPS Equipment Tag No. Type Fluid Description Temperature Suction Pressure Discharge Pressure Flow Density of Liquid at WPT Viscosity of Liquid at WPT Power Absorbed at Shaft Material of Construction

305-P-003A/B Reciprocating Lean TEG 99.9% Rated 101.6 0.11 96.8 6.0 1046 3.73 15.8 Casing: AISI 316L; Impeller: AISI 316 L


TEG BURNER AIR FAN Equipment Tag No. Type Fluid Description Temperature

305-K-001A/B Centrifugal Blower Air Rated 25

Unit ºC



Equipment Tag No. Suction Pressure Discharge Pressure Flow Motor Power Material of Construction


305-K-001A/B ATM barg 96.8 m barg 1500 Nm³/h 4.0 kW Casing: AISI 316 L; Impeller: AISI 316 L

TEG MAKE-UP FILTER Equipment Tag No. Type Process Medium Description Design Temperature Design Pressure Operating Temperature Operating Pressure Liquid Quantity Density at WPT Material of Construction Dimensions

305-F-001 Catridge Lean TEG Maximum 82.0 10.0 45.0

Minimum –15.0 — –4.0

3.3 5.0 1104 Shell: KCS; Internals: SS316L 203.2 ID x 1500 TT length

Unit º C barg ºC barg m3/h kg/m3 mm

TEG DRAIN VESSEL Equipment Tag No. Type Process Medium Description Design Temperature Design Pressure Operating Temperature Operating Pressure Material of Construction Dimensions: ID Length (T/T)

305-V-001 Horizontal vessel TEG Maximum Minimum –15.0 82.0 3.5 — –15.0 45.0 0.005 1.5 Shell & Heads: CS 2000 7700

Unit ºC barg (kPa) ºC barg (kPa) mm mm

TEG STRIPPING COLUMN Equipment Tag No. Type Process Medium Description Design Temperature Design Pressure Operating Temperature Operating Pressure

305-C-001 Packed Column Hydrocarbon Gas & TEG Maximum Minimum 280.0 –15.0 3.5 FV 204.0 0.12

Unit ºC barg (kPa) ºC barg (kPa)



Equipment Tag No. Liquid Flow Vapour Quantity Structured Packing Material of Construction Dimensions:

OD Length (T/T)


305-C-001 0.8 160.2 Pall Rings 5/8” -1900 mm Shell & Heads: ASTM A516 Gr60 Internals: Pall Rings 5/8” SS316L 406.4 1900

kg/h kg/h mm

mm mm

TEG DRAIN PUMP Equipment Tag No. Type Fluid Description Temperature Suction pressure Discharge pressure Flow Density of Liquid at WPT Viscosity of Liquid at WPT Motor Power Material of Construction

305-P-001 Vertical Sump Pump Lean/Rich Glycol Rated 45 0.22 2.08 5 1100 57.26 5.5 Casing: SS 316 L; Impeller: SS 316 L


TEG STORAGE TANK Equipment Tag No. Type Process Medium Description Design Temperature Design Pressure Operating Temperature Operating Pressure Operating Capacity Density at WPT Dimension Material of Construction

305-T-001 Tank TEG Maximum –15.0 180.0 0.0

Unit ºC mbarg ºC 20.0 mbarg 28.0 m3 1100 kg/m3 4000 ID x 3000H mm Shell/Bottom: Carbon Steel; Internals: SS 316L

TEG MAKE-UP PUMP Equipment Tag No. Type Fluid

305-P-002 Centrifugal Pump Lean TEG

Minimum 82.0 –2.5 45.0



Description Temperature Suction Pressure Discharge Pressure Flow Density of Liquid at WPT Viscosity of Liquid at WPT Motor Power Material of Construction


Rated 45 0.5 5.56 5.0 1100 40 5.5 Casing: KCS; Impeller: KCS


COLD LEAN/RICH GLYCOL HEAT EXCHANGER Equipment Tag No. Type Fluid Description Design Temp – Plate Operating Temp – Plate Design Pressure – Plate Design Temp – Shell Design Pressure – Shell Operating Temp – Shell Fluid Plate Fluid Shell Heat Duty Material of Construction

305-E-001 Plate Type Heat Exchanger Plate: Lean Glycol; Shell: Rich TEG Maximum Minimum 240.0 –15.0 Inlet: 120.0 Outlet: 73.0 10.3 –1.0 180.0 –15.0 10.3 –1.0 Inlet: 12.0 Outlet:62.0 6201.0 6360.0 204.0 Plate: SA240 316; Shell: SA333 Gr6

Unit ºC ºC barg ºC barg ºC kg/h kg/h kW

HOT LEAN/RICH GLYCOL HEAT EXCHANGER Equipment Tag No. Type Fluid Description Design Temp – Plate Operating Temp – Plate Design Pressure – Plate Design Temp – Shell Design Pressure – Shell Operating Temp – Shell Fluid – Plate Fluid – Shell Heat Duty Material of Construction

305-E-002 Plate Type Heat Exchanger Plate: Lean Glycol; Shell: Rich TEG Maximum Minimum 240.0 –15.0 Inlet :194.0 Outlet :103.0 10.3 –1.0 180.0 –15.0 10.3 –1.0 Inlet: 62.0 Outlet: 150.0 6201.0 6462.0 410.0 Plate: SA240 316; Shell: SA333 Gr6

Unit ºC ºC barg ºC barg ºC kg/h kg/h kW




4.5.2 Process Description After contacting the wet gas, the water-rich glycol (Rich TEG) is regenerated by heating at approximately atmospheric pressure to a temperature high enough to drive off almost all the absorbed water. The regenerated lean glycol is then cooled and re-circulated back to the Gas Dehydration Column (305-C-001). The rich TEG from the 305-C-001 Chimney Collection Tray flows on level control through 305-LV-3017 to the bottom shell side of TEG Reflux Condenser (305-E-003). The rich TEG is heated from 53.7C to 62C by hot glycol vapours generated from the TEG Reboiler (305-H-001). Then the rich glycol is preheated in the Cold Lean/Rich Glycol Exchanger (305-E-001) to 68C in order to achieve the proper temperature for good separation efficiency before entering the Glycol Flash Drum (305-V-002). The Glycol Flash Drum, operating at 4 barg, is a horizontal 3-phase separator which separates the hydrocarbon liquid phase from the glycol phase and vents any remaining gases. The Glycol Flash Drum consists of 3 compartments: the inlet settling compartment, the hydrocarbon (HC) bucket and the glycol outlet compartment. The Glycol Flash Drum is designed for a fixed liquid retention time in the settling compartment for adequate separation of entrained liquid hydrocarbons. The rich glycol leaves the Glycol Flash Drum at 68C, and passes through the Rich TEG Cartridge Filters (305-F-003A/B). Here the rich TEG is purified from eventually entrained solid particles and the remaining hydrocarbons are removed by the TEG Carbon Filter (305-F-002). The rich TEG from the Carbon filter enters the Hot Lean/Rich Glycol exchanger (305-E-002) where it is preheated from 68C to 150C. The rich TEG is fed from the Glycol Flash Drum under level control by 305-LIC-3210 and is distributed on the middle of TEG Still Column (305-C-002). The heat for the distillation is given by hot TEG vapours from the TEG Reboiler (305-H-001). After reboiling, the hot TEG vapours and water move up the TEG Still Column stripping out the water from the rich TEG moving counter currently down the TEG Still Column. The Reboiler Regeneration temperature is maintained at 204C and the fire/fume tubes are designed in order to avoid hot spot with consequent TEG degradation and to reduce the glycol losses to unavoidable minimum. Once the TEG has left the heating section, it reaches a purity of 99.0 wt% and it flows inside the Stripping Column (305-C-003). The TEG Reboiler is a direct-fired Reboiler with a burner assembly burning fuel gas and oxygen in slightly above the stochiometric quantities. The burnt combusted flue gases pass through the U-tube assembly and are finally released to atmosphere at a high elevation stack. The fuel gas required for burning in the Reboiler is first heated in the TEG Surge Drum (305-V-005) and then passed through Fuel Gas KO Drum (305-V-004) to remove any condensate. Then it is passed through Filter Coalescer and burnt in the Burner Assembly of 305-H-001. The fuel gas pressure to the burner assembly is controlled by a self-regulating Pressure Controller 305-PCV-3175 set at 0.5 barg. The primary air required for combustion is supplied by Burner Air Fan (305-K-001A/B). In the U/S of 305-PCV-3175 a 2” line is taken and pre-heated in 305-H-001 and sent to 305-V-005 as stripping gas for 305-V-005. In the Stripping Column, in order to achieve the desired purity of 99.9 wt% of lean TEG purity, fuel gas as external stripping gas is used. The intimate contact of Glycol and stripping gas is ensured by a Pall-ring packing. The regenerated glycol is




collected in the TEG Surge Drum (305-V-005). The regenerated glycol coming from the Surge Drum (305-V-005) is cooled down from 193.6C to 109.6C in the hot Lean/Rich Glycol Heat Exchanger (305-E-002) and then passes through the Cold Lean/Rich Glycol Exchanger (305-E-001) where the outlet temperature reaches 103°C. The pressure is increased to 88.5 bara by means of Glycol Circulation Pumps (305-P-003A/B). The glycol-water vapours move up the TEG Reflux Condenser (305-E-003), on the tube side, cooled by the rich TEG from 305-C-001 on the shell side. In the TEG Reflux Condenser, the glycol vapours are condensed and predominantly water vapour along with little uncondensed TEG escapes. The vapours from the outlet of TEG Reflux Condenser go to Vent Gas KO drum (305-V-003) from where the condensed liquid is sent to Closed Drain System. The uncondensed vapour from the top of 305-V-003 goes to a Vent Gas Blower (305-K-001A/B & 305-K-001C/D) which operates in series. The vent gas flows to the TEG Incinerator where the vapours are burnt with air. Provision is given to route the off-gas to Flare when the Incinerator is not available. The hot TEG is distilled by the removal of water from the rich TEG. The hot TEG vapours from the TEG Reboiler (305-H-001) provide the heat input for the distillation of rich TEG into lean TEG and water. The lean Glycol is pumped by Glycol Circulation Pump (305-P-003A/B) and passes through the Dry Gas/Lean TEG Exchanger (305-E-004) before entering the Dehydration Column (305-C-001) through a flow distributor. The required make-up TEG is pumped from the TEG Storage Tank (305-T-001) by TEG Make-up Pump (305-P-002) and it flows through a TEG Make-up Filter (305-F-001). The TEG Storage Tank (305-T-001) is a conical fixed roof storage tank maintained at a pressure of 80 mbarg with a nominal capacity of 28 m3. The tank pressure is maintained by a self-regulating Pressure Control Valve 305-PCV-3049 by controlling blanket nitrogen to tank. If the tank gets over-pressurized, then it is opened to atmosphere through a vent by a self-regulating Pressure Control Valve 305-PCV-3048. The drain from the various vessels of Gas Dehydration system and TEG Regeneration system is drained into TEG Drain Vessel (305-V-001). From 305-V-001 it is pumped back to the Regenerator system using TEG Drain pump. A Pressure Vacuum Valve 305-PVV-161 is fitted to the tank which will open at a pressure of 140 mbar and at a vacuum of –1 mbarg. 305-PVV-161 acts as a safety device to prevent the tank during the failure of 305-PCV-3048 or 305-PCV-3049.




4.5.3 TEG Regenerator Controls The TEG regeneration package has the following control loops. Glycol Level on Contactor 305-C-001

305-LIC-3017 DCS Controller, PID Action with H & L Alarm Threshold, Direct Action Controller

Wet Condensate Level on Contactor 305-C-001

305-LIC-3013 DCS Controller, Gap Control Action with H & L Alarm Threshold, Direct Action Controller

Off-Spec Gas to Flare from Contactor 305-C-001

305-PIC-3024 DCS Controller, PID Action, Direct Action Controller

Dry Spec Gas Outlet from Contactor 305-C-001

305-PIC-3009 DCS Controller, PID Action with H & L Alarm Threshold, Direct Action Controller

Vent Gas Temperature from TEG Reflux Condenser 305-E-003

305-TIC-3102 DCS Controller, PID Action with H & L Alarm Threshold, Direct Action Controller

TEG Temperature inside Reboiler 305-H-001

305-TIC-3109 DCS Controller, PID Action with H & L Alarm Threshold, Direct Action Controller

Glycol Level on Flash Drum 305-V-002

305-LIC-3210 DCS Controller, PID Action with H & L Alarm Threshold, Direct Action Controller

TEG Reflux Condenser Top Temperature Control The (TEG + water) vapour outlet from TEG Reflux Condenser (305-E-003) outlet temperature Controller (305-TIC-3102) controls the three way valve controller 305-TV-3102 which bypasses the cold fluid to the inlet of 305-E-003 to maintain the top temperature at 95C. TEG Reboiler Temperature Control The TEG Reboiler temperature is controlled by 305-TIC-3109 which controls fuel gas flow through Control Valve 305-TV-3109. The corresponding air flow is adjusted by a mechanical link from the discharge of Air Blowers 305-K-001A/B for the Reboiler Main burner. The Fuel gas flow and air flow link are preset for a fixed Air–Fuel ratio. Fuel Gas Pressure Control and Pilot Gas Pressure Control for TEG Reboiler The Fuel gas pressure for the Burner Assembly of 305-H-001 is controlled by selfregulating Pressure Controller 305-PCV-3175 which controls the fuel gas pressure at 0.5 barg. The Pilot gas is taken at downstream of Fuel Gas Pressure Control Valve 305-PCV-3175 and the Pilot Gas pressure is maintained at 0.3 barg by a self-regulating Pressure Control Valve 305-PCV-3176. Burner Air Fan Controls Fan 305-K-001-A or -B can be selected as duty fan from control room using the selector switch 305-HIS-3182. Normally 305-K-001A or B will be running and is indicated by 305-MIXI-3182/3183. If the running fans trips, then the standby fan will immediately start. The standby fan is always kept in Auto mode as indicated by 305-MHSM-3182/3183 selector switch.




Glycol Flash Drum Glycol & Condensate Level Control The glycol level in the Glycol Flash Drum is controlled by Level Controller 305-LIC-3210 which controls the rich TEG flow through the Control Valve 305-LV-3210. The condensate collected in the Glycol Flash Drum level is maintained by a Level Controller 305-LIC-3206 which adjusts the Control Valve 305-LV-3206 to the closed drain system. Glycol Flash Drum Pressure Control The Glycol Flash Drum pressure is maintained at 3.8 barg by self-regulating Pressure Control Valve 305-PCV-3201 by admitting fuel gas into the Glycol Flash Drum. If the pressure reaches 4.0 barg then 305-PCV-3211 vents gas to flare. For detailed Alarms & Trips Schedule, refer Annexure-6. 4.6

TEG INCINERATOR SYSTEM

TEG Incinerator unit is designed to burn off-gases from TEG Regeneration System and Produced Water Tank. The TEG Incinerator consists of a vertical combustion chamber directly connected to the stack through a flue gas duct, where the flue gas is quenched with dilution air at ambient temperature. The diluted gas is exhausted to the self-supported stack raiser connected with the top of the base chamber. The Combustion Chamber is equipped with a special Burner and an electrically ignitable pilot. The waste gas is directly injected together with support fuel gas and combustion air in to the combustion chamber for burning. The TEG Incinerator is designed to burn gases with the following parameters: TEG Off-Gas 

Flow rate

: 464 kg/h



Temperature

: 30 – 150°C



Pressure

: 0.4 barg

Produced Water Tank Off-Gas 

Flow rate

: 242 kg/h



Temperature

: 8 – 45°C



Pressure

: 0.03 barg

The TEG Incinerator Main Burner has a design capacity of 7 MW/h which is 10% higher than necessary to operate the combustion chamber at 850°C (1562°F) under maximum waste gas flow rates.

The fuel gas consumption for the Main Burner will be as follows: Minimum Normal Maximum

kg/h 8.0 57.3 60.5

Nm3/h 10 72 76

The TEG Incinerator is designed to burn waste gases from the following sources:


00180-PCP-300-PDMan-12503-01 GGS Operating Manual Vol #1 o

TEG Vent Gas KO Drum 305-V-003

o

Produced Water Tank Off-gas


TEG off-gas is introduced through the Burner Gun and Produced Water Tank Off-Gas is introduced directly in the Combustion Chamber. During the chamber pre-heating phase, the main burner is operated with support fuel gas and combustion air only. Preheating operation will be done until combustion chamber temperature reaches 750C. The operating temperature for the combustion chamber is 850°C, maintained by regulating the Fuel Gas flow rate. The TEG Incinerator is: 

provided with a UV scanner for detecting flame of Pilot burner, and



provided with a redundant self-checking UV scanner for detecting flame of Main burner




4.6.1 TEG Incinerator Controls Combustion Chamber Temperature Control (Split Control) The operating temperature for the combustion chamber maintained at 850 deg C by regulating the fuel gas flow rate. 340-TIC-6027 controls the combustion chamber temperature by throttling 340-TV-6027A on the Fuel Gas line and 340-TV-6027B on the dilution air line, in split control. Normally, the combustion chamber temperature is controlled by modulating the fuel gas valve 340-TV-6027A, while the dilution air valve 340-TV-6027B remains fully closed. As the temperature rises above the set point, 340-TV-6027A tends to close to minimum position corresponding to minimum design flow rate allowed for burner operation. In case the temperature continues to rise, the dilution air FO valve 340-TV-6027B starts opening to improve cooling down of combustion chamber. It will have a ‘low oxygen’ override control through 340-AIC-6028, which measures oxygen content at the combustion chamber outlet. In case of low oxygen, 340-AIC-6028 will override 340-TIC-6027 to modulate the dilution air valve 340-TV-6027B. Combustion Air Flow Control Combustion air flow is measured by 340-FI-6031. Fuel gas, TEG off-gas and Produced water off-gas flows are measured by 340-FI-6043, 340-FI-6044 and 340-FI-6046 respectively. These flows are factored (configurable) and added in an adder block, the output of which acts as a set point to 340-FIC-6031 to control the combustion air flow. During the start-up phase, the Heater temperature is brought to 750C in steps of 50C per hour by using fuel gas. The Radiation Temperature Controller 340-TIC-6027 is a split-range Controller with two outputs. The 0–50% signal goes to the Fuel Gas Control Valve 340-TV-6027B. The 50–100% signal from 340-TIC-6027 is compared with the Oxygen Analyzer output 340-AIC-6028 in a Comparator 340-AY-6028 which adjusts the dilution air flow to the TEG Incinerator to maintain the required excess air. Note: Refer vendor operating & maintenance manual for further details. 4.7

UTILITIES

4.7.1 Plant Air System The Compressed Air package provides the necessary amount of compressed air for use as instrument air, plant air and in Nitrogen generation package. The Air requirement for GGS will be satisfied by the Air compressor Package consisting 2 X 100% Skid mounted Oil free Screw Air Compressors type complete with all necessary accessories. The standby machine shall be available for operation in the event of high air usage or in the event that an operating compressor fails. Discharge capacity of each compressor is 1182.4 Nm³/h at 45C with discharge pressure of 10.2 barg. The Air compressor consists of an Inter and After-cooler, Water Separator and Master controller to control Compressor operation. Each Compressor package includes one Aftercooler (325-E-001A/B) after the Compressor. Aftercooler is provided after Compressor package to control outlet air temperature in case of extreme weather conditions. A Plant Air receiver 325-V-001 will be provided downstream of Independent After cooler.




4.7.2 Instrument Air System The Instrument air package supplies air for use as Instrument Air, Plant Air and Nitrogen Generation. 2 X 100% Dryer Package 325-X-002A/B is provided for production of Instrument air at a dew point of -35˚C at 7.5 barg. The Instrument Air Dryer package consists of a Pre-Filter, two molecular sieve bed Adsorption/Regeneration towers, after filter and a Master controller to control Dryer operations. Pressure in the downstream of Instrument air dryer package will be sized to provide at least 20 minutes backup supply to essential IA users excluding Nitrogen within the pressure range of 9.0 barg to 4.5 barg. Part of Instrument Air is used as Plant Air with necessary header pressure control for distribution to Utility hose station. Loading and unloading of the Air compressor will be triggered by monitoring the pressure controller 325-PIC-4732 on instrument air receiver.

4.7.2.1

Process Description

Each compressor package includes one after cooler (325-E-001A/B) for maintaining the discharge temperature to meet system requirements. A wet Air Receiver (325-V-001) will be provided downstream of the compressors.




Wet air from the receiver is routed to Instrument Air Dryer package (325-X-002A/B) which consists of alumina bed absorption/regeneration unit for production of air at a dew point of -35˚C at 7.5 barg. The dryer beds are regenerated using dry instrument air. Each dryer package is provided with Prefilter, Dryer vessel & Afterfilter. Coalescing Air Pre-filters filter any water, dust and foreign matter from Plant Air before it is sent to the Air Dryer Beds. Downstream of the dryer beds, Afterfilters are installed to remove any desiccant fines carried over from the dryers before the air reaches the Instrument Air Receivers. The dried instrument air is then lead to distribution header through Instrument Air Receiver (325-V-002). Instrument Air (IA) Receiver (325-V-002) downstream of the drier package will be sized to provide at least 20-minutes backup supply to IA users (excluding N2 package supply) while the pressure in the receiver falls from 8.5 barg to 4.5 barg for a flow of 495 Nm3/h. Pressure Transmitter 325-PT-4737 is provided on the line going to Instrument Air Distribution Header initiates Plant ESD when instrument pressure falls below 4.41 barg (4.5 kg/cm2g). AIR COMPRESSOR Equipment Tag No. Type Fluid Description Suction Temperature Suction Pressure Discharge Temperature Discharge Pressure Flow Molecular Weight Power Absorbed at Shaft Material of Construction

325-K-001A/B Screw Ambient Air Rated Unit 45 ºC 0.943 bara 54 ºC 11.0 bara 1480.2 Nm3/h 28.99 1485 kW Casing: Cast Iron DIN 1691-64-GG20 Impeller: CS DIN 17200 CK35 – PTFE Coated

INSTRUMENT AIR RECEIVER Equipment Tag No. Type Process Medium Description Design Temperature Design Pressure Operating Temperature Operating Pressure Molecular Weight Material of Construction Dimensions

325-V-002 Vessel Instrument Air Maximum Minimum –15.0 82.0 12.0 — 15.0 50.0 4.5 9.5 28.82 CS 1000 OD x 3000 Length T/T

Unit ºC barg ºC barg

mm


4.7.2.2



Instrument Air Package Controls

Pressure Transmitter 325-PT-4732 will initiate two-level interlock based on the air pressure. When the air pressure drops below 6 barg, it will close On/Off Valve 325-XV-4665 located on the line going to Plant Air distribution header. The second level of interlock which is set at 5 barg to close On/Off Valve 325-XV-4725 located on the Instrument Air supply line to Nitrogen package. The Pressure Transmitter 325-PT-4732 will control loading and unloading of the Air compressors. Instrument Air distribution header pressure will also be provided with pressure Low-Low alarm represented by 325-PALL-4737. Refer Cause & Effect Diagram 250-EPR-CNE-05001. Wet air receiver level is also provided with level High-High trip by 325-LAHH-4653 and high level alarm is indicated by 325-LAH-4650. Refer Cause & Effect Diagram 250-EPR-CNE-05001 ESD Level-3, Unit-325) for more details. The following signals will be available from air compressors for indication in the DCS:



Running status



Shutdown alarm



Common alarm

Note: Refer vendor operating & maintenance manual for further details. 4.7.3 Nitrogen System 4.7.3.1

Process Description

Nitrogen requirement in GGS plant is essentially for blanketing of tanks and secondary gas for compressor seals. The nitrogen Generation package employs Membrane technology for generation of nitrogen from air. The nitrogen Generation Package (324-X-001) consists of one train with a capacity of 68 Nm3/h capacity of 98 vol% purity. The Nitrogen package unit consists of three sections namely: 

Feed Air supply



Membrane nitrogen Generation Section



Product gas

The nitrogen unit can be started or stopped locally or remotely. The feed air is taken from Instrument Air Receiver 325-V-002. Inlet Parameters Parameters Pressure (Min./Max.) Temperature (Min./Max.) Dew point Feed Air Capacity

Unit barg C C Nm3/h

Value 7.0/10.0 15/50 –35°C @ 7.5 barg 230




Product Gas Parameters Parameters Pressure (Min./Max.) Temperature (Min./Max.) Product Capacity

Unit barg C Nm3/h

Value 5.5/7.0 15/+50 68

The Instrument air stream from Instrument Air Receiver (325-V-002) is directed to Nitrogen Generator (324-X-001) through Micron- and Activated Carbon -Filters. The Dry Feed Instrument Air (15 – 50 ºC & 7.0 – 8.2 barg) is led through a set of one-micron filter (324-F-001A) and one AC Filter (324-F-002A) to qualify feed air quality. One standby set of Micron Filter (324-F-001B) & AC Filters (324-F-002B) are provided to allow change-over for maintenance of filters. The feed air is then heated in Heater (324-H-001) to 50ºC (max). The filtered and dried feed instrument air is then fed to nitrogen Generation Package (324-X-001). The oxygen-rich waste gas is discharged to atmosphere at a safe location. The generated nitrogen stream is continuously analysed for oxygen content by Oxygen Analyzer (324-AIT-4619) provided on downstream of membrane modules. A total number of five membrane modules constitute the package wherein three operate and two are spared to take care of maintenance requirement of any two modules at a time. The package is designed to supply 68 Nm³/h of nitrogen with 98% product purity under normal operation at 5.5 barg (min) and 7 barg (normal) pressure and 45–50C temperature. If nitrogen is found to be off-specification, it is automatically vented to atmosphere at safe location. Additional requirement for flare purging (if any) is provided by back-up bottle supply system. The produced nitrogen is then routed to nitrogen Storage Receiver (324-V-001). The receiver is sized to provide 10-minutes hold-up for normal operation design flow of 68 Nm3/h. The nitrogen distribution system takes the supply through this storage receiver to cater to GGS plant nitrogen demand. Back-up supply of nitrogen will be provided by nitrogen bottles. It will supplement the nitrogen receiver whenever required.




NITROGEN RECEIVER Equipment Tag No. Type Process Medium Description Design Temperature Design Pressure Operating Temperature Operating Pressure Molecular Weight Material of Construction Dimensions

324-V-001 Vessel Nitrogen Maximum –15.0 12.0 15.0 5.5

Minimum 82.0 — 50.0 8.2


28.0 SS-316 1900 OD x 4700 Length T/T

mm

324-V-001 Vessel Wet Air Maximum –15.0 12.0 15.0 8.0


WET AIR RECEIVER Equipment Tag No. Type Process Medium Description Design Temperature Design Pressure Operating Temperature Operating Pressure Molecular Weight Material of Construction Dimensions 4.7.3.2

Minimum 82.0 — 50.0 9.5

28.82 CS 1000 OD x 3000 Length T/T

mm

Nitrogen Package Controls

The package purity will be set at 98% purity for nitrogen. If the package purity for nitrogen has reached to 97% or below, On/Off Valve 324-XV-4616 will be closed from local control panel and Off-spec Vent Valve 324-XV-4620 will be opened; off- spec gas from the package will be vented until nitrogen purity has reached 98%. If it continues at nitrogen purity of 97% or below for more than 15-minutes, then the package will undergo shutdown. A common alarm will be provided for ICSS indication in case of any fault in the package. Similarly Oxygen Analyzer 324-AIT-4619 provided in the package continuously monitors oxygen percentage and High High and High alarms will be generated in ICSS system when oxygen content goes high. It is possible to stop nitrogen package from ICSS and shutdown of the package will be initiated when nitrogen goes below 97% for more than 15 minutes. Emergency shutdown of the heater is initiated when the skin temperature of the heater goes High (324-TAHH-4602). The following signals will be available for indication to ICSS: 

Common alarm





Heater running



High oxygen alarm



High differential pressure alarm



Heater outlet gas temperature high and low


It is possible to stop nitrogen system from ICSS Note: Refer vendor operating & maintenance manual for further details 4.7.4 Utility Water 4.7.4.1

Utility Water Description

Raw water used in GGS area is required for drinking water purposes and for utility water in hose stations. The source of raw water for GGS area is Bore-well. Raw water is pumped from the wells using the Bore-well Water Pump 326-P-001A/S of 23 m 3/h capacity and fed to the Utility Water Tank 326-T-002. The Utility Water tank is designed for 171 m3 capacity corresponding to 7-day hold up of utility water. The Utility water requirement for hose stations and potable water is 20 m 3/day. The bore-hole water pump is controlled based on the Utility Water Tank level by the ON-OFF Level Controller 326-LIC-4760. The water is then pumped by 326-P-003A/B which is configured in Duty/Standby mode, to the plant utility water distribution header at a controlled pressure. The pressure of the header is controlled by the Pressure Controller 826-PIC-4763 which acts on the Control Valve 326-PV-4763 in the return line. UTILITY WATER TANK Equipment Tag No. Type Process Medium Description Design Temperature Design Pressure Operating Temperature Operating Pressure Operating Capacity Density at WPT Dimension Material of Construction

326-T-002 Tank Water Maximum –15.0 3.5 4.0

Minimum 82.0 –2.5 45.0

Unit ºC mbarg ºC 1.5 mbarg 171.0 m3 997.0 kg/m3 6000 ID x 7200H mm Shell/Bottom: Carbon Steel; Internals: SS 316L




BOREHOLE WATER PUMP Equipment Tag No. Type Fluid Description Temperature Suction Pressure Discharge Pressure Flow Density of Liquid at WPT Viscosity of Liquid at WPT Power Absorbed at Shaft Material of Construction

326-P-001 Submergible Centrifugal Raw water Rated 45 0.9 14.1 23.1 995 0.764 47.74 Casing: CS ; Impeller: CS


UTILITY WATER PUMP Equipment Tag No. Type Fluid Description Temperature Suction Pressure Discharge Pressure Flow Density of Liquid at WPT Viscosity of Liquid at WPT Power Absorbed at Shaft Material of Construction 4.7.4.2

326-P-003A/B Centrifugal Utility Water Rated 45 0.67 7.6 11.6 995 0.765 8.24 Casing: CS; Impeller: CS


Utility Water System Control Description

The pressure of the utility water recirculated to Utility Water Tank 326-T-002 from utility water distribution header will be controlled by Controller 326-PIC-4763 acting on Control Valve 326-PV-4763. Utility Water Tank 326-T-002 level will be controlled by 326-LICA-4760 from DCS by means of On/Off Controller which will control START/STOP of the Bore-hole Pump 326-P-001A/S. Utility water tank level is also provided with High- High and Low- Low alarms which are indicated by 326-LAHH-4761 and 326-LALL4761. Refer Cause & Effect diagram 250-EPR-CNE-05001. Note: Refer vendor operating & maintenance manual for further details




4.7.5 Potable Water System 4.7.5.1

Potable Water Description

Potable Water is delivered by road tankers and unloaded into the Potable Water Tank 326-T-003 using a potable water tanker Unloading Pump 326-P-004. Potable water will be stored in 326-T-003 of capacity 12 m3 considering 3-day hold-up for potable water consumption. Potable water from the tank is then pumped by Potable Water Distribution Pumps 326-P-005A/B in to the Plant Distribution Header after getting treated in Potable Water Sterilisation package 326-X-005. The sterilisation package is a Chlorination Injection Facility in which the chlorine dosing (NaOCl) into potable water and is controlled based on Free Residual chlorine (FRC) in the potable water return line measured by the ORP(Oxygen Reduction Potential) Analyzer 326-AT-4605. The Potable Water Pump 326-P-005A/B, configured in Duty/Standby mode, should be started prior to the start of sterilisation package. The unit can be operated locally from the field LCP or from DCS, based on the Local/Remote selection in the LCP. As the unit is started, the pre-chlorination sampling is taken and if the chlorine level is lower than the value set by the ORP Analyzer 326AT-4605, Chlorine Dosing Pump 826-DPM-006 will start. Once chlorine level reaches the set value, dosing pump will stop. Manual Stop is possible from field as well as from DCS. The typical potable water and its parameters are given in the following table: Operating Pressure Operating Temperature Design Pressure Design Temperature Conductivity Total hardness Chloride Ions Fe Turbidity

(min/norm/max) (min/norm/max) (min/max)

2.5/5.3/5.8 (ambient)(1) 6.5 -15/82 250 Desirable 150-500 200 0.3 5

barg ºC barg ºC µS/cm mg/l CaCo3 mg/l mg/l Units

In Auto mode, when either of the potable water pump 326-P-005A or B starts (i.e. ‘RUN’ feedback is received), sterilisation unit START command is issued (326-HS-4802) to start the chlorination dosing pumps. The unit will automatically stop when both the potable water pumps are not running. Refer Appendix-A for motor control and interlock details. Potable Water Sterilisation system is a standalone packaged unit. All control and safeguarding functions will be implemented in the supplier’s local control panel. ‘Common Fault alarm’, ‘common trip’ etc. shall be generated by the package and made available to DCS. Refer supplier’s documents for complete details.




POTABLE WATER TANKER UNLOADING PUMP Equipment Tag No. Type Fluid Description Temperature Suction pressure Discharge pressure Flow Density of Liquid at WPT Viscosity of Liquid at WPT Power Absorbed at Shaft Material of Construction

326-P-004 Centrifugal Pump Potable Water Rated 45 0.26 1.5 10 993 0.765 1.28 Casing: SS 316L; Impeller: SS 316L


POTABLE WATER DISTRIBUTION PUMP Equipment Tag No. Type Fluid Description Temperature Suction Pressure Discharge Pressure Flow Density of Liquid at WPT Viscosity of Liquid at WPT Power Absorbed at Shaft Material of Construction

4.7.5.2

326-P-005A/B Centrifugal Potable Water Rated 45 0.37 5.36 6.25 993 0.765 1.73 Casing: SS316L; Impeller: SS316L


Potable Water System Control Description

The pressure of the potable water recirculated to potable water tank from potable water distribution header will be controlled by 326-PIC-4789 (set point ATM) and Control Valve 326-PV-4789. The potable water is chlorinated so as to have a Free Residual Chlorine (FRC) value of 0.2-0.5 ppm at the final outlet. The Chlorination unit will start only when Potable Pump 326-P-005A or 326-P-005B is running. The following signals will be taken from sterilization package to DCS system: o

Common fault alarm

o

Running indication

In addition to the above, START and STOP shall be possible from DCS system. Potable water tank is also provided with level High-High (326-LAHH-4771) and Low Low alarms (326-LALL-4771). Refer Cause & Effect Diagram 250-EPR-CNE-05001.




Note: Refer vendor operating & maintenance manual for further details 4.7.6 Diesel System Diesel will be used in GGS as an alternative fuel for GTGs and in the Emergency Diesel Generator. It is also used in the vehicle filling stations. Diesel is used as an alternative fuel for GTG in case fuel gas is not available. The diesel fuel used for the GTG should meet the following specifications and supply conditions. Diesel Quality PARAMETER Operating Pressure (Min/Norm/Max) Operating Temperature(Min/Norm/Max) Grade Quality

UNIT barg ºC Free Water

Particulates Density at 15°C Viscosity at 15°C Lower Heating Value Pour point

kg/m3 cP kJ/kg ºC

VALUE 4.5/5.0/5.5 Ambient Automotive Grade <100 ppmv 99.9% of Particles >5 micron removed 860 35.2 42800 –10

Diesel Consumption 

Diesel will be used as an alternative fuel for 2x100% GTGs and as fuel in 1x100% diesel-driven generators for emergency power generation. Consumption figures tabulated below are based on vendor values.



Diesel will be routed to filling stations where the same will be dispensed to individual diesel consuming vehicles through standard pump and dispenser systems. Consumption is 3 m3/h (50 lpm).

No facility for underground storage of diesel is envisaged in vehicle filling stations. Consumption Diesel Users GTG-A or -B Emergency Power Generation

MW 2.5 1.2

Diesel kg/h 1205 (*1) 319.4 (*2)

Required Pumping Rate m3/h 1.6 (*1) 0.4 (*2)

(*1) Heat rate 20622 kJ/kWh (Vendor data)

(*2) With 10% margin on vendor consumption figures 4.7.6.1

Description of Diesel System

Clean diesel is brought into the plant by tankers and unloaded into an atmospheric diesel storage tank (322-T-001) located in the GGS area using Diesel Tanker Offloading Pump (322-P-002). Pump capacity is 10 m3/h and tanker unloading will be done only during daytime (6 hours).




The atmospheric Diesel Storage Tank of nominal capacity 59 m3 is based as backup supply to emergency generator for 7-days. Since the GTG is dual-fired, no storage of diesel has been considered for the GTG operation. Diesel will be pumped by Diesel Transfer Pump (322-P-001A/S) to Diesel Pre-filter (322-F-001A/B - 2 filters of duplex type) for removal of any particles. Diesel Transfer Pump capacity is 5 m3/h. One pump is provided in the warehouse as standby. Then it flows through Diesel Filter Coalescer (322-F-002A/B) to bring down the water content from 1000 to 100 ppmv. The filtered diesel flows through distribution header and then to consumers in GGS. Diesel circuit will be maintained pressurized to ensure supply to GTG if gas supply fails. A spill-back line is provided from the discharge of Diesel Transfer Pumps to the Diesel Storage Tank 322-T-001. 4.7.6.2

Diesel System Control Description

When Diesel Storage Tank 322-T-001 level is High High (322-LAHH-3402), it will initiate emergency shutdown by stopping diesel tanker Unloading Pump 322-P-002. When diesel Storage Tank 322-T-001 level is Low Low (322-LALL-3402), it will stop Diesel Transfer Pump 322-P-001A. If Diesel Transfer Pump suction pressure is Low Low (322-PALL-3422), it will initiate shutdown by stopping Diesel Transfer Pump 322-P-001A, GTG and Emergency Diesel Generator. For more details, refer Cause & Effect Diagram 250 - EPR-CNE-05001.

4.8

FUEL GAS SYTEM

Fuel gas is supplied at two pressure levels in the GGS. The HP fuel gas at 25 barg (HP fuel gas pressure set for Gas turbine requirement) will be used to run Gas turbine drives. This HP fuel gas is filtered to have 99.9% removal of particles of 100-micron size. The LP fuel gas at 5 barg will be used for: o

Blanketing of various process tanks and vessels

o

Flares as pilot and purge gas

o

Stripping gas for TEG regeneration

o

Fuel Gas for TEG regeneration

o

Fuel in TEG incinerator and direct fired heater




Fuel Gas Consumption The consumption of fuel gas is based on lean gas operation in summer time and the following other parameters. Power Generators There are 2X100% power generators driven by gas turbines. Gas turbine HP fuel gas consumptions are based on vendor data for operation of one GTG HP Fuel Gas Consumption for Gas Turbines Load LCV Heat Rate Total Fuel Gas Consumed Peak Fuel Gas Demand (2 GTG Operating at 60% load 5.62 MW)

o Based on a load of 9.367 MW

MW kJ/kg kJ/kWh kg/h

9.367 41176 (35 MJ/Nm3) 11094 2460*

kg/h

3480




Typical HP fuel gas properties and composition are given in Table given below: Parameters Operating Pressure Operating Temperature Design Pressure Design Temperature Molecular weight LHV Solid Particulates COMPOSITION H2S H2O TE GLYCOL Nitrogen CO2 Methane Ethane Propane i-Butane n-Butane i-Pentane

LP – Lean Gas

LP – Rich Gas

Sum

Wint

Sum

Wint

barg

26

26

26

ºC

29.6

29.92

28.4

Unit

barg ºC kJ/kg

HP

26

Lean Sum 26

Rich Wint 26

28.69

30.25

28.82

30 30 30 30 30 30 82 82 82 8 82 82 19.27 18.94 19.45 18.89 19.1 18.92 44737 44736 48250 48360 47948 48360 99.9% of particles <100 microns removed

Mol % 0 0 0 1.42 3.26 87.47 3.97 1.92 0.38 0.69 0.3

0 0 0 1.43 3.26 87.98 3.96 1.87 0.36 0.62 0.22

0 0 0 0.77 0.36 86.51 6.5 3.09 0.56 1.04 0.35

0 0 0 0.78 0.36 87.52 6.5 2.94 0.5 0.86 0.23

0 0 0 1.43 3.24 87.8 3.92 1.86 0.36 0.63 0.25

0 0 0 0.79 0.35 87.71 6.32 2.79 0.47 0.82 0.25

a) Stripping Gas LP Fuel gas is used as stripping gas for TEG regeneration. Quantity required is 85 kg/h as per vendor data. It is used in the TEG Surge Drum; it strips the water vapour from the stripping column to produce lean TEG concentration of 99.9 % purity. Flares: LP Fuel gas will be used to purge flare vent headers and to fuel the pilot burners on the flares and used as fuel in the TEG Reboiler. Flare vent purging is typically done with fuel gas introduced at the furthest point away from the flare, in quantities to assure a velocity that will yield a visible flare from the control room. Velocity is adjusted in the field once the flare is operational by visual inspection of the flare at night. Based on a fuel gas velocity of 0.01 m/s the requirement of fuel gas for flare purging is estimated as follows: LP Fuel Gas Requirement for Purge Flare Details Fuel Gas to Header at 0.1 m/s for purging at 0.5 barg, 30C (24” dia) Fuel Gas for Pilots (3 burners & 2 kg/h for each) Ignition Gas Total Fuel Gas per Flare

Unit

Continuous

Intermittent

kg/h

121.0

—

kg/h

6.5 — 127.5

— 4.6 —

kg/h




b) Blanketing LP Fuel gas will be used for blanketing (in-breathing) Produced Water Tank, TEG Drain Vessel, Methanol and Chemical Injection Storage Tanks. In-breathing is needed because of liquid movement (pumping out) and thermal changes (cooling). Blanketing requirement has been calculated based on API 2000. Typical Fuel gas composition is given in the Table given below: Parameters

Units

Operating Pressure Operating Temperature Design Pressure Design Temperature Molecular weight LHV Solid Particulates COMPOSITION H2S H2O TE GLYCOL Nitrogen CO2 Methane Ethane Propane i-Butane n-Butane i-Pentane

barg ºC barg ºC kJ/kg

LP – Lean Gas

LP – Rich Gas

Sum

Wint

Sum

Wint

5.0 16.0

5.0 16.0

5.0 16.0

5.0 16.0

HP Lean Sum 5.0 16.0

Rich Wint 5.0 16.0

9.0 9.0 9.0 9.0 9.0 9.0 82.0 82.0 82.0 82.0 82.0 82.0 19.3 18.9 19.5 18.9 19.1 18.9 44737 44736 48250 48360 47948 48360 99.9% of particles <100 microns removed

Mol % 0.00 0.0 0.0 1.4 3.3 87.57 3.97 1.92 0.38 0.69 0.30

0.00 0.0 0.0 1.4 3.3 87.98 3.96 1.87 0.36 0.62 0.22

0.00 0.0 0.0 0.8 0.4 86.51 6.50 3.09 0.56 1.04 0.35

0.00 0.0 0.0 0.8 0.46 87.52 6.50 2.94 0.50 0.86 0.23

0.00 0.0 0.0 1.4 3.3 87.47 3.97 1.92 0.38 0.69 0.30

0.00 0.0 0.0 1.4 3.3 87.98 03.96 1.87 0.36 0.62 0.22

FUEL GAS KNOCK-OUT DRUM Equipment Tag No. Type Process Medium Description Design Temperature Design Pressure Operating Temperature Operating Pressure Liquid Quantity

321-V-001 Knock-out Drum – Vertical Hydrocarbon Gas & Condensate Maximum Minimum 82.0 –29.0 35.0 30.0 28.0 26.0 22.0 250.0

Unit ºC barg ºC barg kg/h



Equipment Tag No. Density at WPT Vapour Quantity Molecular Weight Density at WPT Material of Construction Dimensions


321-V-001 750.0 4300.0 19.17 22.52 Shell: CS; Internals: SS316L 1500 ID X 4500 TT

kg/m3 kg/h kg/m3 mm

FUELGAS HEATER Equipment Tag No. Type Process Medium Description Design Temperature Design Pressure Operating Temperature Operating Pressure Design Duty Density at WPT Material of Construction

321-H-001A/B Electrical Fuel gas Maximum –15.0 95.2 9.2

Minimum 82.0 — 55.0

Unit ºC barg ºC barg kW kg/m3

Minimum 82.0 — 48.4

Unit ºC barg ºC barg kW kg/m3

85.86 85.0 69.3 SS 316L

FUELGAS SUPER HEATER Equipment Tag No. Type Process Medium Description Design Temperature Design Pressure Operating Temperature Operating Pressure Design Duty Density at WPT Material of Construction

321-H-002A/B Electrical Fuel gas Maximum –15.0 35.0 28.4 85.86 55.0 68.7 SS 316L

4.8.1 Fuel Gas System Control Description The high pressure fuel gas flows to power generator packages 323-X-001A/B. At high fuel gas pressure PIC-3306 (set point) will actuate either PV3306 or PV 3343 through a selector switch which is provided in HMI and allows required gas flow (22-26 barg) to power generator packages (323-X-001A/B).




The Pressure Controller 321-PIC-3308 (set point–5 barg) will actuate Control Valve 321-PV-3308 which will control the pressure of fuel gas from KO Drum to cater LP Gas to small users. Two Fuel Gas Heaters 321-H-001A/B (1 working + 1 standby) are provided, each controlled by its own thyristor control panel to heat the fuel gas such that LP fuel gas consumers in FG distribution network should have gas at a temperature of at least 15C at their end. When the working heater is faulty, it will switch on to standby heater by opening 321-XV-3403 On/Off valve and switching on Standby Heater and later faulty heater is tripped. But the closing of the On/Off Valve 321-XV-3402 on faulty heater will be after a time delay of xx seconds. Fuel Gas Heaters (321-H-001A and 321-H-001B) are also provided with temperature High High trips 321-TAHH-3363 and 321-TAHH-3373. Feed to Fuel Gas KO Drum gas outlet temperature is provided with High High and Low Low temperatures trips (321-TAHH-3314 & 321-TALL-3314). Refer Cause & Effect Diagram 250-EPR-CNE-05001 for more details. The let-down gas is routed to a KOD where condensate is removed. At high level in the KOD, 321-LIC-3311 will actuate Control Valve 321-LV-3311 which allows condensate to flow to Flare Header. Level Controller works on Gap Control philosophy which opens the Level Control Valve at a High level (1100 mm) and closes at Low level (600 mm). The valve continues to be in closed condition until it reaches a higher level and then opens. Fuel Gas KO Drum level is also provided with High-High level (321-LAHH-3312) and Low-Low level (321-LAHH-3312) alarms. Refer Cause & Effect Diagram 250-EPR-CNE-05001 for more details. The Fuel Gas for GTG will be routed through one of the super-heaters 321-H-002A/B, each controlled by its own thyristor control panels. The heat input to the heaters will be controlled by Differential Temperature Controllers 321-TDIC-3323 (Super-heater-A) and 321-TDIC-3400 (Super-heater-B) which will measure the difference between the temperature of super-heater outlet and KO Drum outlet. Fuel gas super-heater outlet temperature is also provided with High-High temperatures trips (321-TAHH-3324 & 321-TAHH-3401). Fuel gas super-heater temperature is also provided with High High temperature trips (321-TAHH-3383 & 321-TAHH-3393). For more details refer Cause & Effect Chart 250-EPR-CNE-05001. Feed to Fuel Gas KO Drum pressure is provided with pressure High-High and Low-Low trips which are indicated by 321-PAHH-3307 and 321-PALL-3307. Refer Cause & Effect Diagram 250-EPR-CNE-05001 for more details. 4.9

FLARE SYSTEM

The High Pressure Flare System serves the purpose of safely gathering and disposing of any hydrocarbon released from operational Flare Valves, Relief Devices or Blowdown Valves from equipment. Header from GGS is routed to KOD as a single HP Flare Header. The relief discharges from various equipment in GGS is collected through a 24” Flare Header which flows through the Flare Knock-Out drum (331-V-001). The KO Drum is provided with Heater (331-H-001) to keep temperatures above 0C. The liquid from KO Drum is pumped back to the Production Separator. Because of the pressure during HP mode of operation, Booster Pumps (331-P-001A/B) and 331-P-002A/B are used in series to transfer liquid from Flare KO Drum to Production Separator. During LP mode of operation, 331-P-001A/B only are used.




The Flare KO Drum is sized for a design droplet diameter of 300-microns. It is provided with an elbow/diverter plate-type inlet device. Pumps are actuated by Level Control in Flare KO Drum. LP fuel gas is to be used for purging, ignition gas and for the pilots. Connections for start-up fuel gas are also provided. Flare header load and size shall be determined based on relief and blowdown study.

FLARE KO DRUM Equipment Tag No. Type Process Medium Description Design Temperature Design Pressure Operating Temperature Operating Pressure Volume Material of Construction Dimensions

331-V-001 Vessel Hydrocarbon gas/Condensate/Water Maximum Minimum –62.0 175.0 3.5 — Amb 129.9 0.15 0.7 96.6 Shell: SS316L; Internals: SS316L 3000 ID x 12600 Length T/T

Unit o C barg o C barg m³

mm

FLARE KO DRUM HEATER Equipment Tag No. Type Process Medium Description Design Temperature Design Pressure Operating Temperature Operating Pressure Design Duty Material of Construction

331-H-001 Electrical Condensate + Water Maximum Minimum –62.0 175.0 3.5 — 4 –4 0.15 0.7 35.0 SS 316L

Unit ºC barg ºC barg kW




FLARE KNOCK-OUT DRUM BOOSTER PUMP Equipment Tag No. Type Fluid Description Temperature Suction Pressure Discharge Pressure Flow Density of Liquid at WPT Viscosity of Liquid at WPT Motor Power Material of Construction

331-P-001 A/B Centrifugal Pump Saturated Hydrocarbon Rated 45 3.71 34.53 10 765 0.85 54.02 Casing: CS; Impeller: CS


FLARE KO DRUM PUMP Equipment Tag No. Type Fluid Description Design Pressure Design Temperature Suction Temperature Suction pressure Discharge Temperature Discharge Pressure S.G at Operating Temperature Flow Motor Material of Construction

331-P-002A/B Rotary Hydrocarbon Liquid Rated Unit 45.0 barg 82.0 ºC 30.0 ºC 34.6 barg 50.0 ºC 91.6 barg 0.62 10.0 m3/h 45.0 kW Casing: Cr SS (12%); Impeller: Cr SS (12%)

4.9.1 Flare System Controls All monitoring and control of the Flare system, except for the Flare Stack Package shall be from GGS or GTP. Flare stack with the Ignition Control Skid is supplied as a standalone package and is independently controlled from a local control panel. Flare K.O. Drum Temperature Control Liquids received by the Flare KO drum (33-V-001) may be cold under certain relief/blowdown conditions. 331-TIC-5110 controls the drum temperature by thyristor control of drum’s electrical Heater 331-H-001. The heater is protected by the thyristor control panel to prevent element overheating.




Flare KO Drum Level Control 331-LIC-5100 controls the drum level and removes the liquids from the flare drum periodically using an On/Off DCS control by START/STOP of Flare KO Drum Booster Pumps 331-P-001A/B and 331-P-002A/B. However, this is inhibited when 331-TI-5110 is below the Low control set point to protect the Pump and its associated piping. Flare KO Drum Booster Pumps 331-P-001A/B Flare KO Drum Booster Pumps 331-P-001A/B are configured in Duty/Standby mode. Duty/Standby pump selection will be done by the operator from the DCS HMI. For the Auto operations, both Duty and Standby motors shall be in ‘Auto’. For simplicity, Pump-A is on duty and Pump-B is in Standby mode. When 331-LI-5100 increases above the High control set point, the following sequence takes place:

o 331-LIC-5110 output sets the output of 331-P-001A/B Duty Booster Pump Motorcontrol-block to 1 i.e. ‘Start’ command for the Duty Booster Pump of 331-P-001A is sent to PMS over the serial link. o

In case still the level 331-LI-5100 doesn’t reset below the High control set point within ‘xx’ minutes (configurable) after the Duty Booster Pump-A has started, the Standby Booster Pump-B will automatically start and the Duty Booster Pump-A shall be stopped, i.e. 33-LIC-5100 output sets the output of 331-P-001A/B Standby booster pump’s motor-control-block to 1 (‘Start’ command for the Standby Booster Pump is sent to PMS). Upon receipt of Standby pump running feedback, 33-LIC-5100 output sets the output of 331-P-001A/B Duty Booster Pump-A motor-control-block to 0 (‘Stop’ command for the Duty booster pump-A is sent to PMS).

o

331-P-001A/B shall continue to run till 331-LI-5100 falls below the Low control set point. Stop command for booster pump 331-P-001A/B is sent to PMS over the serial link. 331-P-001A/B shall stop and remain stopped till 331-LI-5100 increases above the High control set point and the cycle will continue.

DCS Interlocks Close 331-XV-5129 at the discharge of Flare KOD pump 331-P-002A/B when both pumps 331-P-001A and B are ‘Stopped’ and open 331-XV-5129 when 331-P-001A or B starts running. 331-P-001A/B and 331-P-002A/B start is inhibited if the Flare KO Drum temperature 331-TI-5110 is below the ‘Low’ control set point. The High and Low control set points are different from the High and LOW alarm set points and shall be adjustable. Flare KO Drum Pumps 331-P-002A/B




Flare KO Drum Pumps 331-P-002A/B shall be configured in Duty/Standby mode. Duty/Standby pump selection shall be done by the operator from the DCS HMI. For the Auto operations, both Duty and Standby motors shall be in ‘Auto’. Flare KO Drum pump 331-P-002A/B which is in Duty will automatically start after ‘xx’ seconds (configurable) from the start of Flare KO Drum booster pump 331-P-001A or 331-P-001B. During LP mode, Flare KO pumps 331-P-002A/B will be bypassed. Hence, the motorcontrol-blocks for these pumps shall disabled, i.e. ‘Start’ operation shall be inhibited and alarms will be suppressed. Flare Package The gas from the flare headers is fed to the flare package and is ignited by the local ignition panel, which is part of the package. Local control panel performs the functions of igniting, monitoring the flare pilots and controlling the pilot flow. Only critical signals like the ‘Ignition Fail’, ‘Fuel Gas Low Pressure’ and ‘Common Alarm’ will be generated by the package and made available to the DCS operator. For detailed Alarms & Trips Schedule, refer to Annexure-6. 4.10

PRODUCED WATER SYSTEM

The Produced Water Treatment is designed to remove oil from the produced water separated in the Production Separator and Condensate systems. Produced water from the Production separator under Level Controller 302-LIC-1114 flows to the Produced Water Degassing Drum through the Control Valve 302-LV-1114. Similarly liquid from Condensate Coalescer under Level Controller 302-LIC-1156 flows through 302-LV-1156 to the Produced Water Degassing Drum. Pressure inside Produced Water Degassing Drum is maintained by the Pressure Controller 334-PIC-5449 by opening and closing 334-PV-5449 at High and Low set point of 334-PIC-5449. Degassing Drum is fitted with two Pressure Safety Valves 334-PSV-0165A/B set at 5 barg. Degassed Produced Water from 334-V-001 flows to Produced Water Tank under the control of Level Controller 334-LIC-5441. Produced water storage tank (334-T-001) is sized for a capacity of 740 m 3 corresponding to a working volume equivalent to 4-days of water disposal volume. The skimmed oil from the Produced Water Tank is routed to the closed drains. The tank is blanketed with LP fuel gas to avoid oxygen ingress and the vent line is connected to the TEG Incinerator system. Blanketing pressure is maintained by two self- regulating Pressure Control Valves 334-PCV-5408 and 334-PCV-5409. A Pressure-Vacuum Valve 334-PVV-170B set at a pressure of 140 mbarg and a vacuum of –2.2 mbarg prevents the tank from the effect of pressure. An Emergency Vent 334-EV-5433 is also fitted to the top manway. Produced water is pumped to road tankers via LP Produced Water Disposal Pumps (334-P-001A/B). Tie-in connections will be provided downstream of Produced Water Disposal Pumps (334-P-001A/B) as a future provision for Methanol Injection System.


4.11



DRAIN SYSTEM

The drainage system is designed to allow disposal of liquid inventory and surface water run-off in a safe and environmentally acceptable manner. 4.11.1 Open Drain System The Open drain system will collect aqueous drains that may be expected to contain hydrocarbon liquids, greases, waxes, etc. Sources include pump drip trays, sample points, sample coolers and equipment containing process water. It will comprise of piped collection system. The drain liquids will be routed to a paved area drain collection hub from where it will flow by gravity to open drain sump. Parameter Total Hydrocarbon Content (Inlet/Outlet) Acidity Temperature Increase BOD COD TSS Phenols Sulphides Heavy Metals (Total)

Unit mg/l pH °C mg/l mg/l mg/l mg/l mg/l mg/l

Chlorides

mg/l

Guideline Value 200/30 expected 6.0 – 9.0 3 25 125 35 0.5 1 5 Average 600; Maximum 1200

Water run-off from paved areas (precipitation, vessel wash water, fire water) will be routed to Drain Hub in each area. Liquids from Drain Hub will flow by gravity to open drain sump. No separate accidental oily water sump is envisaged in GGS. Open Drain Sump 332-V-001 will have 3 compartments. Water will flow into the second compartment through an underflow. Oil skimmer in the first compartment with inbuilt pump will route the skimmed oil to 3rd compartment. The oily water is transferred to Produced water tanks (334-T-001) through 332-P-002A/S pump where oil is separated by gravity from water. Vertical submersible pumps 332-P-001A/S will pump the treated Water to Holding Pond. It is required to have oil content not more then 30 ppm (w/w) in separated water. The Open Drain Pump is sized for 400 m3 sump on the basis of 8 hours of two utility water hoses operation. The Sump pump shall be designed to empty the sump in 8 hours at the most. A storm water drainage system will be provided to collect rain water run-off from the roads and buildings, a network of open ditches and channels will convey this water to the holding pond. Water from this holding pond will be used as required for irrigation purposes within the camp and administration building areas; excess water will be discharged to the surface/disposed off as required. Hazop Action No. 384 The capacity of the Holding Pond is designed for the worst rainfall conditions. Partially open manual valves in the Water Disposal Pumps will cause overflow of water from the




Holding pond to be spilled over to the surrounding environment. Normally the Holding pond receives non-contaminated water from the Open Drain Sump and Storm water. If entrained oil is present in the Holding Pond, it can be recycled to the open drain sump for reprocessing. Under these conditions of entrained oil in the Holding pond, over flow of water from holding pond will create environmental problems. A portable skimmer can be employed to remove traces of oil in the Holding Pond so that at any time the water is free of oil in the Holding pond. A portable skimmer available at GTP also could be used. If heavy rainfall occurs for a considerable period, a separate Operator can be stationed round the clock to monitor the Levels and quality of water for the Open Drain System. Hazop Action No. 391 The contaminated water from the Open Drain Sump is pumped by Open Drain Contaminated Sump Pump (332-P-002A/S) to Produced Water Storage Tanks through a check valve and 3” dip pipeline with a siphon breaker. If Check valve is passing and water level is below dip leg level, then there will be gas migration from Produced Water tank to Contaminated Open Drain Sump. Hence the Operating personnel should ensure water level above dipleg and then only open the valve to the Contaminated Sump Drain Pump which will prevent gas migration and thereby avoiding potential Fire and Explosion hazard. 4.11.2 Closed Drain system The Closed drain system receives drains from equipment/vessels and low point drains from pipelines. Prior to shutdown of a process unit, the liquid level of vessels is reduced as low as possible through the normal process outlet in order to minimise the final liquid inventory in the vessels. Once the process unit has been shut down and equipment have been isolated, and depressurized, the liquid inventory remaining in the unit can be drained to the closed drain system. Process vessels operating at very high temperature should be allowed to cool down before discharging the residual liquid to the closed drains. The GGS plant Closed Drain Drum (333-V-001) is sized to have a working volume equal to the volume contained by the Production Separator up to the top of the weir plate. The liquid from closed drain drum will be removed by submerged Closed Drain Drum Pumps (333-P-001A/B), (2x 100%) and routed to the Flare KO Drum. A provision is given to empty the closed drain drum through truck. The pump is designed to empty the closed drain drum hold-up in 8 hours. The pumps are controlled by an On/Off Controller 333-LICA-5304 which starts and stops the pumps at the High and Low set points of the controller. Low Low temperature of 333-TALL-5320 will trip the pumps 333-P-001A/B. The Closed Drain Drum has an electric heating coil (333-H-001) which is provided to heat any collected liquids to maintain the liquid temperature above 4C and prevent ice formation. The heater is switched ON and OFF at the high and low set point of Temperature Controller 333-TICA-5306. The heater will trip on High High element




temperature 333-TT-5313. There is a provision to empty Closed Drain drum to Road Tanker. 4.12

POWER GENERATOR SYSTEM

The Power Generator for GTP runs only on Fuel gas system. The schematic sketch of the Gas Turbine is given below: Fig. 7 – Schematic sketch of a Gas Turbine

The various systems of a Gas Turbine Unit are described below: Lubrication Oil The lubrication oil system has three pumps (Auxiliary, main and emergency) to circulate oil to provide cooling and lubrication of the turbine, gearbox and driven unit bearings. The control system will operate the auxiliary pump when the main gearbox pump is unable to deliver sufficient lubrication oil pressure (during turbine run up and run down). The Emergency Oil Pump is used to supply lubrication oil to the hot section bearings and will be operated when the auxiliary pump has failed to deliver sufficient pressure. Oil pressure is monitored by a low pressure transmitter and will initiate a turbine shutdown when the oil pressure is insufficient to maintain safe turbine operation. Lubricating oil temperature, monitored using a thermocouple, is maintained within operating limits by the use of a tank heater and a thermostatically controlled cooler. The lubrication oil tank is fitted with level and temperature monitoring, and




heater control to ensure there is sufficient oil at the required temperature for turbine operation.



Up to 2 additional oil tank heaters for cold ambient



Triple oil cooler fans with vibration switches



Oil supply temperature high trip transmitter

Gas Fuel Gas fuel is supplied to the engine burners via an off-skid block and vent system, an onskid double block and vent system, and metering valves. The control system positions and monitors the block and vent valves dependant upon the operating requirements. During a start the integrity of the on-skid block and vent valves is proved by pressure rise and fall tests. In cold climates the control system can be configured to flow gas to vent (for a short period) to ensure it is above a minimum temperature that is safe to run the engine. The fuel metering valves are positioned by an independent integrated gas fuel valve controller depending on current fuel demand from the turbine governor, and local gas fuel pressure and temperature. There is also provision for the operator to initiate a Controlled change from gas fuel running to liquid fuel running. Liquid Fuel and Purge Control is provided for an off-skid fuel forwarding pump (customer supply), an off-skid block valve, an on-skid boost pump, metering valves, and block valves. Prior to the block valves there are prime valves which are operated to ensure that the liquid fuel system is full. A prime is initiated during a liquid fuel start, prior to a change to liquid fuel and periodically while running on gas fuel. During the liquid fuel prime a small amount of liquid fuel is pumped into the turbine drains tank. The controller sequences the pumps and valves and positions the metering valve to obtain light-up, stable running, fuel changeover and turbine shutdown. The liquid burner system is purged using process air or air from the turbine compressor. The valves that control the purge and air selection are operated automatically by the control system on a shutdown or after a changeover from liquid fuel in order to minimise carbon build up on the burners. There is also provision for the operator to initiate a controlled change from running liquid fuel to running gas fuel. The liquid fuel system is often used as a standby fuel in case of a problem with gas fuel supply. As such the controller is capable of automatically changing to liquid fuel if such condition arises. An automatic change from gas fuel to liquid fuel will be initiated should a rapid reduction in gas pressure be detected or the differential pressure across the gas throttle fall below 1.9 bar. Elements



Gas assisted liquid starting



Propane assisted liquid starting

Governor The turbine governor controls gas turbine speed by varying fuel demand to the fuel system metering valves. The fuel demand is calculated using turbine shaft speed, gas




path temperatures, gas path pressures, and turbine load. The turbine gas path temperatures (Gas exhaust temperatures are used to optimise the turbine performance and keep it within operating limits. Deviation from the limits is protected by initiating a turbine shutdown. The turbine gas path pressures (gas generator inlet, compressor delivery, and interduct) are measured to ensure that the gas turbine is running within its operating envelope. Any deviation from the operating envelope will initiate turbine shutdowns. The turbine shaft speeds (gas generator and power turbine) are measured to ensure that the turbine is not approaching or in an over speed condition. The turbine bearing temperatures are measured to protect the bearings from over-temperature. The radial movement of the turbine shafts is monitored to detect high levels of vibration. Ventilation System The turbine enclosure is fitted with a ventilation system to provide cooling for the gas turbine and enclosure mounted equipment and a gas free environment in which to operate the turbine. The control system will operate the ventilation fan to maintain a purged enclosure while the unit is operating and afterwards during the cooling period. While the fan is running the enclosure air flow is monitored to ensure it is sufficient to supply adequate cooling and maintain a fully purged enclosure. Elements



Dual vent fans operating as duty/standby where the operator has the ability to select the duty fan.



Differential pressure monitoring of the ventilation inlet filter to indicate to the operator that the filters are blocking and require servicing.



An inlet filter scavenge fan which runs when the enclosure ventilation system is running.

Combustion Inlet and Exhaust The combustion inlet is fitted with a filter across which the differential pressure is monitored to advise the operator that servicing is required. If this does not happen, the increasing differential pressure will eventually cause the turbine to be automatically shutdown Elements A scavenge fan fitted to the combustion inlet filter. Fire and Gas Monitoring System The turbine controller (PLC) monitors the fire and gas detection system. If the fire controller detects a fire it signals the PLC to initiate a turbine shutdown, the gas fuel system will be isolated/vented, enclosure ventilation fans are inhibited, enclosure dampers will close and the emergency lubricating oil pump will run.




The level of gas present at the turbine enclosure ventilation exit is measured and if the level detected is too high then a turbine shutdown is initiated and the gas fuel system is isolated and vented. The enclosure ventilation fan will continue to run to extract the gas. The level of gas present at the turbine enclosure ventilation/combustion inlet is measured and if the level detected is too high then a turbine shutdown is initiated and the gas fuel system is isolated and vented. The enclosure ventilation fan will be isolated to prevent gas being drawn into the enclosure. Turbine Compressor Washing System The turbine has connections for a compressor washing system. Washing can be initiated with the turbine stopped (cold wash) or with the turbine running (hot wash). The operator connects the wash module to the turbine and initiates a wash sequence which comprises of a wash cycle followed by a rinse cycle. Seal Air System The turbine uses process air and P2 air from the compressor (when the shaft is rotating at speed where sufficient pressure is being developed) to provide a seal which prevents oil carry over from the bearings. The controller operates a valve to supply the process air to the seals during turbine run up and shutdown. The pressure of the sealing air is measured to ensure it is within turbine operational limits. Fluid Drains System The off package drains tanks (Supplied by Siemens for hydrocarbons, water wash, oil, etc) are monitored by high level warning and shutdown transmitters respectively. Control is provided for an automatic drain valve to ensure that any remaining fluids are drained from the turbine into the drains system prior to running. Starter System Control is provided for a hydraulic starter system. The control system drives the starter system to spin the gas turbine during start up and shutdown, and accelerate it during the start sequence. The windings of the electric motor are monitored to prevent damage by overheating. Air Flow Control The air flow through the engine is controlled by modulating the variable guide vanes and blow off valve, and operating the interstage bleed valves. The interstage bleed valves are used to prevent a compressor surge during the run up. The variable guide vanes are used during a turbine start to control the air flow into the compressor to prevent engine surge. They can also be used for emissions control while running. The blow off valves are operated to prevent the engine from over speeding during a load reduction. Control of these devices will keep the engine within its operating envelope and prevent events such as surge and over speed. Driven Unit Generator The generator windings, bearings and cooling air are all monitored to protect components against over temperature. Control of dual cooling fans and monitoring of a filter’s differential pressure is provided.



5.0

ELECTRICAL



5.1



ELECTRICAL SYSTEMS

The Gas Gathering Station of EBLA Surface Facilities has in-house stand-alone Captive Power Generation enough to meet the Facility’s power load requirement of HV and LV loads. The HV Loads are being supplied at 11 kV and LV loads are supplied at 400 V. Main power for each plant is supplied from two 11 kV, 12 MVA (Alternator rating at 35C) gas turbine-driven generators. However, at the Gas Gathering Station, the power generation with Turbine on gas as fuel is limited to 8955 kW at 35°C and to 8045 kW at 45C. The power generation with turbine on liquid fuel is limited to 7934 kW at 35C & to 7216 kW at 45C. Under normal circumstances i.e. up to an ambient temperature of 26C, one GTG is expected to cater to all the loads in the plant. However, when the ambient temperature in the plant increases beyond 26C, the GTG output ratings get reduced. At that time the generation will have to be supplemented either with power from an Emergency Diesel Generator (EDG) or another GTG to meet the maximum plant loads. During starting of the second Field Gas Compressor also, the second GTG will be required. Under normal operating condition, the HV switchboard will operate as a single bus. The VSDS loads of Field Gas Compressors (1-operating and 1-standby) at the Gas Gathering Station are the only load on the 11 kV bus. At the Gas Gathering Station, 11 kV is stepped down to 400 V through two 2.5 MVA and two 1.6 MVA transformers. In addition to GTGs, there is also a 1500 kVA Emergency Diesel Generator which is brought into service on loss of power supply from the GTGs. The EDG has been rated to provide power to shutdown and maintenance loads of the plant, as well as the Start-up Auxiliary load of one GTG. At times when the Plant is running at maximum plant load, the EDG has to be run in parallel with one GTG when maximum power generated by one GTG gets reduced at higher ambient temperatures. During power failure from GTG, the EDG will supply power to all the Well head, Telecom and Instrument UPSs in CCR building, Substation UPS and to the HVAC of CCR and Substation buildings. During initial phase of plant operation i.e. when the Field Gas Compressor is not running, it will be powered from one GTG. The GTGs are designed to operate continuously in a satisfactory manner without any deterioration of its life even at low loads (i.e. load down to as low as 1.0 MW on Fuel gas). The various voltage levels for the power distribution to motors in Well heads and GGS is as follows: Motors above 1500 kW

11 kV, 3 Phase, 3 Wire, 50 Hz AC with system neutral earthed through resistance

Motors from 0.20 kW to (including) 233 kW

400V, 3 Phase, 3 Wire, 50 Hz AC with system neutral solidly earthed

Motors less than 0.20 kW

230 V, 1 Phase, 2 Wire, 50 Hz AC

There is no MV (3.3 kV) load at the Gas Gathering Station.




The LV loads at GGS are distributed over three 400 V switchboards, namely, Process MCC, Utility MCC and Emergency MCC. Both Process and Utility MCCs (400V, 3 Phase, 4 wire switchboards) are fed from their respective transformers with 100% redundancy. The Emergency Switchboard is fed from the Utility MCC during normal operation. Emergency Diesel Generator feeds Emergency Switchboard during power failure from GTG. Well head loads are fed from the Emergency MCC installed at GGS Substation building. The voltage is stepped up to 3.3 kV through Well head Step-up Transformers (one for each of the seven Well heads) at the GGS facility and power is transmitted through underground cables up to each Well head location where the voltages is stepped down to 420 V through respective Well head step-down transformers (again, one for each of the seven Well heads). Well head loads are fed from one local Power Distribution Board which is fed by respective Well head step-down transformer. Each PDB in addition is connected to a portable Emergency Diesel Generator capable of feeding the Well head load during an emergency. In case of failure of the normal power supply from the GTG, the Auto-Start of the EDG set will be initiated by the LV emergency switchboard so that the emergency loads are powered for safe shutdown of the plant and also to ensure that the vital systems are running for quick restarting of plant. Instrument systems are operated on 230 V, 1 Phase, 50 Hz supply derived from 400 V, 3 Phase, 4 wire distribution boards of two equal-rated, physically & electrically separate UPS systems, each with its own battery. Telecom supply is 230 V, 1 phase, 2 wire derived from 230 V, 1 phase, 2 wire distribution boards of two equal-rated, physically & electrically separate AC 50 Hz UPS systems, each with its own battery. Instrument and telecom loads at each Well head are fed from two 230 V, 1 phase battery backup power packs located at each Well head. The period of battery back-up for UPS will be 6 hours. Batteries will be charged to 90% duty within 10 hours. Systems will be capable for repeat duty in 24 hours. Each GTG and EDG is provided with a dedicated 110 V/24 V DC battery and batterycharger to take care of the power requirements of the control system and the emergency lube oil pumps. 5.1.1 Electrical System Controls The Plant operation is envisaged as ‘Automatic’ with the minimum number of Process Operators. Accordingly, the electrical system is designed for automatic operation as far as possible. Separate server and RTU-PLC based Power Management System (PMS) is being provided at the GGS facility of the EBLA project for system monitoring and switching control via Integrated Protection and Control devices (IPCDs) or intelligent devices. PMS at GTP has supervisory control over PMS at GGS, through a redundant Fibre Optic Link. PMS is time-synchronized with the Plant Telecom System using NTP protocol. The PMS provided at the substation of GGS will communicate with the individual electrical equipment associated with the substation via serial link. Communication protocol is Modbus Serial except for Siemens-make VSDS of Field Gas Compressors where Profibus to Modbus converter will be used. In addition, the PMS is linked to the upstream plant ICSS via serial communication link. The ICSS is provided for Plant




process control and monitoring. PMS will act as gateway between ICSS and Electrical Power Equipment. The control and monitoring function carried out by the PMS with respect to the individual equipment is as detailed in the following sections. The PMS will also provide Sequence of Event (SOE) reports including running time, number of starts, and, number and type of trips. It will also carry out recording of all events, date- and timestamped for all circuits connected, with printout facilities including running/stopped/alarm/ trip. Time-stamp for events will be given by Data Acquisition RTU and the same will be communicated to SCADA for SOE logging/printing. Load Sharing Load sharing is performed from PMS and its signals are initiated from selected active and reactive set points. Based on Load Monitoring results and unit operation constraints, e.g., unit High and Low MW loading limits, maximum response rate, system regulation margin and spinning reserve requirements, de-rating based on ambient temperature, fuel as gas or liquid; the set points will be available for sharing Active and Reactive power. The set points are defined such that proportionate sharing of power happens. Depending on the load balance requirements, alarm will be generated if the load is beyond the predefined limits. The PMS system provides request for running of new Generator, if necessary. Interconnection of PMS with switchboards, ICSS, UCP and location of HMI for GGS is in line with PMS Block Diagram 300-EEL-SLD-029. The details of electrical equipment connected with the PMS are as follows: PMS-GGS (PMS for Gas Gathering Station: 323-PMS-1-1) o

Two nos., Unit Control Panel (UCP) + Generator Control Panel (GCP) – Intelligent Generator Protection Relay, AVR, Exciter Controls etc. and a common Synchronizing Panel.

o

11 kV Main Switchboard

o

VSDS Panel (2 Nos.)

o

400 V Utility MCC

o

400 V Process MCC

o

400 V Emergency MCC

o

Emergency DG Set Control Panel

o

230 V AC UPS (4 Nos.)

o

110 V DC UPS (2 Nos.)

Well head loads and UPS are monitored and controlled by ICSS via an optical fibre link through a Well head RTU and are not under the purview of the PMS-GGS. The MV and LV process motors ‘Start/Stop’ control is carried out by the ICSS via the PMS.




For heaters without ‘Start/Stop’, control is carried out by the ICSS via the PMS whereas for heaters with separate control panels, the ICSS controls the heaters directly. The ICSS will also receive the ‘Run, Stop, Trip & Available’ status of all the MV and LV motors and metering input of all the Switchboard incomers and MV motors from the PMS. Emergency shutdown of the electrical equipment is initiated by the ESD system through hard-wired signals to the individual equipment feeder. The electrical LV Switchboard control philosophy for normal and emergency conditions comprises the following options: Normal Switchboard a.

Local Control for the Incomer breakers under ‘Test’ position.

b.

Remote Control from the PMS under ‘Service’ position.

Emergency Switchboard a.

Local Control for the Incomer breakers under ‘Test’ and ‘Service Position’.

b.

Remote Control from the PMS under ‘Service’ position.

The Selection of local or remote control is done manually for Incomer & Bus coupler and outgoing ACB feeder from the switchboard. It is possible to trip every circuit breaker from local to the panel, irrespective of position of Local-Remote (L/R) switch. Monitoring is not affected by the position of the Local/Remote control switch. Lock-out relays can only be reset locally, and not from the remote position. The status of the individual feeder on switchgear can be observed at local switchgear panel and at the PMS. 5.1.2 Electrical System Start-Up Condition-A – Plant Electrical System Start-Up Sequence During initial start-up of the plant, the following sequence of operations shall be followed. Seven steps are described below: Step 1: The objective is to start the EDG for plant start-up. o

Ensure that incomer breakers and outgoing feeders of the Plant Emergency MCC are all OPEN.

o

Start manually, the Emergency Diesel Generator set from the Local Power Panel or EDG control panel of the EDG set.

(a) Black Start: The EDG set can be started if the starting batteries are in fully charged condition. The starting batteries of the EDG set are rated for 3-starts with an interval of 10-sec before lockout. Alternatively, the EDG can be started using compressed air system with sufficient storage to provide air for 3-starts with an interval of 10-sec. (b) Energize the Emergency MCC by closing the DG Incomer Breaker on to the DeadBus. The closing of the breaker is automatic if DC-UPS power is available and is




carried out manually from the LV switchboard if the DC-UPS supply is not available. Step 2: The objective is to energize all emergency and critical process loads connected to the GGS Substation for Plant start-up. Following critical loads on the Emergency Switchboard are to be switched ‘ON’ manually or from MCCS. o

Outgoing feeders to Main Emergency Lighting Distribution Board connected to emergency switchboard

o

Outgoing feeder to Auxiliary Distribution Board of EDG

o

Outgoing feeder to substation HVAC panel

o

Outgoing feeder to control room HVAC panel

o

Outgoing feeder to substation AC UPS

o

Outgoing feeder to substation DC UPS

Additionally any or all of the following loads can be switched ‘ON’, as required from the switch itself. o

Outgoing feeder to Emergency Auxiliary Distribution Board

o

All outgoing feeders from 230 V AC UPS Distribution boards

o

All outgoing feeders from 110 V DC UPS Distribution boards

o

Outgoing feeder to Switchboard for GTG-A or B

o

Outgoing feeder to other critical loads, if any

Based on the process requirement, the following process loads fed from emergency MCC can be started from ICSS through the PMS, as the case maybe.

o Outgoing feeder to Instrument Air Compressor-A/B/C (only one allowed to start) o

Outgoing feeder to HP & LP Methanol Injection Pump Electric Motor

o

Outgoing feeder to nitrogen Generation Electric Heater Thyristor Control Panel

o

Outgoing feeder to Flare KO Drum Pump Electric Motors

o

Outgoing feeder to Flare KO Drum Thyristor controlled Electric Heater.

o

Outgoing feeder to other critical process loads (if any) connected to the Emergency Switchboard

Step 3: Objective is to start GTG and energize the 11 kV switchboard. Energization of 11 kV switchgear at the Substation: The dead-bus closing of the bus-tie from common synchronising panel is to be carried out. PMS will generate hard-wired close




permissive interlock for closing circuit of incomer breaker after ensuring that 11 kV switchboard is healthy and all incoming and outgoing feeder breakers are open. (In manual mode 11 kV Incomer and Bus Tie Breakers can be closed in Test position from switchboard). Operator to ensure that the 11 kV switchboard is a continuous bus with all bus-coupler breakers closed before closing the incomer breaker during plant start-up condition. Identify and start one of the GTGs (either GTG-A, or GTG-B). The feeders of the GTG-Auxiliaries shall be in ready to start condition, so that they can start when the signals are received from the GTG-UCP. The list of GTG Auxiliaries is as follows: o

Starter Motor

o

Lubricating Oil Pump Motor

o

Oil Mist Eliminator Fan

o

Liquid Fuel Oil Pump

o

Main Enclosure Vent. Fan 1 & 2

o

Vent Air Filter Fan Bleed Fan

o

Wash Water Skid Motor

o

ABLOC Fan 1, 2 & 3

o

CACA Fan 1 & 2

o

Lube Oil Tank Heater No-1, 2 & 3

o

GT Gas Fuel Trace Heating

o

Fire Protection System

o

Engine Cleaning Unit

o

Combustion Air Filter

o

Ventilation Air Intake Fan Motor Control

All these feeders are housed in the respective Gas Turbine Generator MCC Switchboard fed from the Emergency MCC. The first GTG is brought into circuit by dead-bus closing of its 11 kV incomer breaker. The incomer circuit breaker ‘Close’ command from CSP is routed through PMS to ensure that 11 kV switch board is healthy and only one Neutral Earthing Resistor (NER) is in circuit for earthing of neutral of 11 kV system. On closing of the first GTG incomer breaker on to the HV switchboard, the 11 kV system gets energized and the 11 kV bus Voltage, kW and current feedback along with breaker status is available to the PMS and selectively to ICSS. Step 4: Objective is to energize the Distribution On receipt of the above information, the Operator from PMS initiates the closing of the 11 kV distribution transformer breakers at the HV switchboard and charges the distribution transformers.




Steps 5: Objective is to energize the Switchboards o

Close breakers 52-U1 & 52-U2, 52-P1 & 52-P2 (323-MMS-1-1) and energize the Utility and Process MCC Switchboard with the respective Bus-coupler breakers kept open.

Step 6: Objective is to switchover from the EDG supply to GTG power o

Close tie breaker -52E1 in the Utility MCC to supply LV power from the Utility MCC Switchboard to the Emergency Switchboard.

o

Operator to initiate the Auto-synchronizing of the Tie Breaker-52E2 (These tag Nos. are with respect to operating philosophy SLD) (Refer Doc. 300-EELDBP-001) (Emergency Switchboard) either from the PMS or from the EDG GCP (EGCP) panel. The synchronizing of the EDG is done by the synchronizing panel within EGCP. On achieving synchronism (of EDG with normal supply) the command to close the Tie Breaker-52E2 is issued by the EDG GCP panel automatically.

o

On closure of Breaker-52E2 in the Emergency Switchboard, the normal and EDG supplies are running in parallel and feeding the Emergency Switchboard load.

o

This is followed by un-loading of the EDG and tripping the EDG incomer Breaker-52E2 from the EDG- GCP panel.

At this stage, all the main HV & LV switchboards (Utility, Process & Emergency) are energized and in normal operation. The HV & LV loads of Process and Utility can be started. Step 7: Objective is to start the other GTG (if required) and HV loads with pre-conditions of the minimum power requirements. With the normal and emergency LV loads in operation, the first GTG is fully loaded. Based on the process operating requirement, the operator has to decide on the starting of the other GTG. The standby HV motor loads are to be started considering the running reserve capacity of the GTGs. Identify and start the second GTG (either GTG-A or GTG-B)). The feeders for the GTG-Auxiliaries are kept in ready to start condition, so that they can start when the signals are received from the GTG-UCP. Once the voltage and frequency builds, start-up of second GTG is complete, operator to initiate the Auto-synchronizing of the Incomer breaker from the PMS. On achieving synchronism, the command to close the Incomer breaker-52E2 is issued by the GTG common synchronizing panel automatically.




5.1.3 System under Plant Normal Operating Condition o

Under plant normal operating condition, one or two GTGs are running and feeding power to the 11 kV HV Switchboard. Load sharing between GTGs is to be achieved through PMS.

o

All the bus-coupler breakers of the HV Switchboard are closed and the HV Switchboard will operate as a continuous bus.

o

All the outgoing power transformer breakers of the HV Switchboards are in circuit feeding loads, LV power to Utility and Process & Emergency switchboards.

o

The outgoing LV Utility, Process and Emergency power and motor feeders are in circuit based on the process operating conditions.

o

The Emergency DG is under standby condition.

o

The 230 V AC UPSs are energized and continuously feeding the instrument, telecom and the PMS loads of the plant.

o

The 110 V DC UPS is energized and will feed the breaker control supply of the HV, & LV Switchboard.

o

The 24V DC System of the each of the GTGs are energized and feeding the critical loads of the GTGs.

o

GTG MCCs have two incomers, one connected to Utility MCC and the other to Emergency MCC. When power is fed to plant from GTG, the incomer connected to Utility MCC will be kept on and the other will switched off.

5.1.4 Electrical System – GTG Failure There are five different situations as follows: Situation 1: Tripping of the GTG (One GTG supplying the plant) due to fault o

Under plant normal operating condition, when the GTG supplying the entire load of the plant trips on fault, the entire plant will be shut down.

o

Only the AC and DC UPS supply is available catering to the plant critical instruments, telecom and control supply for HV/LV breaker operations.

o

On loss of normal supply and on sensing of sustained under-voltage condition at the mains incomer of Emergency MCC, the under-voltage




relay at Mains Incomer of Emergency MCC will initiate an emergency ‘Start’ command to GCP of EDG. o

The EDG is expected to develop the rated voltage in 20 seconds. The breaker-closing

operation

switchboard

carried

is

to out

ensure by

the

power PMS

to

the

emergency

automatically

without

intervention of the operator, based on initiation from the EGCP. The PMS will also carry out the tripping of the tie feeder from Utility MCC manually to prevent back-feed of power from the Emergency DG to Utility Switchboard. With this, critical emergency loads at Emergency boards is catered by the EDG set via the power feeders that will remain closed even on loss of Main GTG power. Motor feeders shall however be started manually since on loss of power, these feeders would have tripped on account of supply under-voltage. o

Once the operator has established and cleared the fault that caused the GTG tripping, the running GTGs is brought back into circuit. In the event of a major fault on the tripped generator, then the operator has to establish the process power requirement by bringing in the Standby Generator into circuit.

Situation 2: Tripping of one of the two GTGs due to Fault o

On tripping of one of the operating GTGs, the PMS will sense a sustained under- voltage/under-frequency condition, if the operating load on the system at the instant of GTG tripping is greater than the capacity of the one operating generator.

o

To prevent the remaining operating Generator from tripping on undervoltage or under-frequency condition, on loss of power from the tripped GTG, load shedding shall be resorted to in real time through hard-wired commands (for HV loads) or serial link (for LV loads) and shall be performed by PMS. PMS shall be pre-programmed with load-shedding priority tables.

o

The philosophy for load shedding in GGS will be developed in coordination with process operation group depending on the priority of loads.




Situation 3: Tripping of a large Motor: Field Gas Compressor Motor (GGS) due to Electrical Fault o

Under plant normal operating condition with one or two GTGs feeding the plant loads, when one of the large motors, say, the Field Gas compressor motor trips, a sudden load throw-off condition is sensed by the 11 kV System.

o

The GTG control panel will sense an over-voltage or over-frequency condition. The Control Systems of the GTGs – Siemens Simatic-400 PLC which are all operating in parallel, will sense an over-voltage or overfrequency condition on the 11 kV System due to the sudden rejection of a large load. Accordingly the PLCs will reduce the output speed and voltage of the operating GTGs. The quantum of load rejection or load acceptance which each GTG has to share shall be in proportion to the inertias of the GTGs.

o

On loss of one of the large motors, the ICSS shall take up control of the process by closing of the necessary loads based on the Plant Process Operating philosophy.

o

Operator shall study the Electrical Fault Sequence of Events (SOE) recorded at the PMS/ICSS causing the tripping of the large motor on fault. Based on the type of fault, the operator shall decide if the fault is major or minor.

o

If minor, the fault shall be cleared by the operator in minimum time keeping the generator/s in operation on reduced load. On clearance of the fault, the large motor shall be brought back into circuit by the operator via ICSS at the specified loading conditions.

o

If the fault is major requiring a major process shutdown, then one of the two GTGs may be tripped, causing the plant to operate only on one GTG feeding the plant minimum load.

Situation 4: Sustained Overload Condition on the Running System

o During sustained overload on the system, as monitored by the PMS/DCS, the Operator/PMS can initiate the starting of the second GTG or EDG if time permits. Else the operator/PMS shall initiate the tripping of noncritical loads to maintain the load within the generation capability of




one GTG. The tripped loads can be brought back into circuit by the operator after starting of the 2 nd GTG. In case any 11 kV or 400 V large loads are being started by ICSS, it should check whether the load shall overload the generator/s or not through the PMS. The PMS will keep the ICSS updated by sending the total available power at any instant as an analog signal through the serial link. Situation 5: Tripping of Power Transformer feeding the Bus-section-A/B of Utility/Process Switchboard o

On loss of supply to bus-section A or B of the Utility or Process MCC, under-voltage condition is sensed at the switchboard which will then self-initiate a slow bus transfer, enabling the closing of the bus-coupler breaker within a short duration, thus resuming power to the entire switchboards.

o

In case of failure of Auto-transfer, the affected bus section load will lose power. In the event of power loss to the bus section feeding the emergency switchboard and in the event of Auto transfer fail, the emergency switchboard associated with that section will also lose power. The EDG is started only on sustained under-voltage on Utility switchboard which implies a loss of main GTG power.

o

If the EDG is required to be operated to meet the emergency switchboard loads which has lost normal source of power, then the operator shall take a conscious decision and carry out manual closing of the EDG incomer breaker and tie feeder breaker from the EDG control panel after ensuring the normal power tie feeder is tripped due to loss of power and not on account of fault. The starting of the EDG to meet this scenario is purely at operator discretion. Once the normal power is established, the reverse paralleling sequence to establish normal power to the emergency board will also be carried out by the Operator manually from the EDG CP.

For the generator control and protection, each of the two GTGs is provided with its own generator control panel (GCP) which houses the Simatic-400 PLC. The GCP shall house the generator protection, control and metering equipment and includes the following functionalities: o

Generator Synchronization/Breaker Control

o

Generator Excitation




o

Generator Protection Monitoring

o

Automatic Voltage Regulation (AVR)

o

Metering

o

Interlocks with Unit Control Panel (UCP) will have its own Simatic-400 PLC (for turbine sequencing, control, governing and protection) and ICSS, both of which are located in the Control Room

The GCP controls and monitors the generator synchronization/excitation process and ensures the generator does not exceed its design limits under any operating condition, for example, the GCP protects against over-current/voltage, reverse power, etc. When limits are exceeded, the turbine will be signalled to shutdown. Some key system readings (such as generator power and reactive power) are passed to the Turbine Control Panel to allow the GCP to control turbine speed during synchronization. Generator breaker position is monitored by the Turbine Control Panel which in turn gives permissive to the GCP during the synchronization process. The Turbine Control Panel monitors the vibration and temperature of generator bearings and the generator winding. High readings will result in turbine shutdown. o

GCP will also perform the following functions: Excitation control (for Automatic voltage regulation/power factor control/reactive power control). The system provided has the ability to automatically synchronise the unit to the bus through operator action initiated from the GCP panel. The control system will also provide protection against high temperature of generator stator windings.

o

Composite Generator protection with Numerical relay Siemens make 7UM6211 (part of GCP) having following protection functions: 27undervoltage protection, 32-Reverse Power protection, 40-generator field failure protection, 51V-Voltage controlled time dependant overcurrent

protection,

protection,

51-IDMT

87-differential

over-current protection,

relay, 58-diode

59-overvoltage supervision,

81-under-/over-frequency protection, 46-Negative phase sequence protection. o

Meters – ammeter, frequency meter, kW/kVAR meter, voltmeter, power factor meter, synchroscope, exciter field ammeter, exciter field voltmeter.

o

Selector/Control switches including – Local/Remote selector switch, Auto/Manual selector switch, Voltage/speed – Raise/Lower pushbuttons,




Generator output breaker control switch, manual synchronizing lights, and manual synchronizing interlock switch. The GCP will provide facility for both manual- and Auto-synchronization of the generators. However manual synchronizing is not envisaged for this plant under plant normal operating condition. The GTG starting and synchronizing is carried out by the operator from the GTG CSP. The synchronizing process can be carried out either in manual mode or in Auto mode as decided by the operator. The CT/PT inputs required in the GCP for synchronizing are derived from Generator and HV switchgear panel through hard-wired analog signals. Once the system is ready for synchronizing, the incomer HV breaker ‘Close’ command is initiated by the CSP via hard-wired signal and the generator is synchronized to the bus. The incomer breaker ‘Close’ command from CSP is routed through a close permissive interlock from PMS which ensures that 11 kV system is healthy. Interlocking circuitry at CSP ensures that one and only one NER is in circuit. The generator status, protection and metering signals are available on the GCP front panel. In addition, these signals are communicated from the GCP/HV Switchboard to the PMS via serial link. Also, necessary signals pertaining to the generator is communicated from the PMS to the ICSS via serial link. Voltage and speed control signals from PMS can control the Active and Reactive loadsharing components of the GTG when running in parallel. The control supply of the GCP is 24 V DC and is derived from dedicated battery system being supplied as part of the GTG package. Interlocks 

The generator is connected to the NER through a local operated isolating device. The generator income breaker closing logic will ensure that the generator is permitted to close only if the incomer earth switch is open.

5.2

EMERGENCY DIESEL GENERATOR SET

Emergency DG Set Design The Emergency Generator supplies power to the Emergency Switchboards to meet the essential service/start-up loads including the following: o

AC & DC UPS

o

GTG auxiliary power supply switchboards

o

Emergency generator auxiliary power supply switchboard

o

Diesel Transfer Pump

o

Flare Knockout drum pumps and Electric Heater

o

HP and LP Methanol Pumps

o

Start-up Fuel Gas Heaters

o

Ignition Transformer for flare package

o

nitrogen Generation Electric Heater




o

Instrument Air Compressor Package

o

Field Gas Compressor auxiliaries which require safe shutdown or quick start-up

o

Main Emergency Lighting Distribution board

o

HVAC Loads (Substation, Control Room)

The emergency load is powered from EDG 400 V, 50 Hz, 1500 kVA, 1200 kW Emergency Diesel Generator set. The EDG set is designed to start automatically on loss of main power. The EDG set package is complete with Auto-mains failure control panel, excitation system, AVR and other accessories. The neutral of the DG set is solidly earthed. Emergency DG Set Operation & Control DG Control – EDG Control Panel (EGCP) in substation DG Protection – EDG Control Panel (EGCP) in substation DG Status Monitoring – EGCP/PMS/ICSS During normal operation, the Main GTGs are feeding power to the system, the incomer breaker from 400 V Utility Switchboard to the emergency switchboard is in ‘CLOSED’ condition and the incomer breaker from EDG set is in ‘OPEN’ condition. However, during tripping of both GTGs, emergency power for plant loads including GTG shutdown load will be fed from EDG. The EDG set will normally be brought into service on loss of the main power supply from the GTGs. The loss of power from the main GTGs, and the sustained simultaneous under-voltage condition on Emergency Switchboard, will initiate an Auto-start command for DG through EGCP. The EDG is provided with a EGCP located in the substation which contains the protective relays and meters. The AVR is housed in the Local Power Panel which is housed within the EDG acoustic enclosure. In addition to the above, the EDG set is also provided with synchronizing facility to enable parallel operation with the main power system for regular testing of the set, and reinstatement of normal power to the essential services system. Under plant normal operating condition, periodic partial load test on the EDG set is carried out by the operator to ensure the healthiness of the EDG set. The emergency switchboard is designed to withstand the short circuit current that could occur during such operation. The EDG control panel (EGCP) will house the protective relays, which will provide following protection functions for EDG: Voltage-controlled, time-dependent over-current relay (51V), over-voltage/undervoltage relay (59/27), inverse definite minimum time lag (IDMTL) over-current relay (51), negative phase sequence relay (46), under-/over-frequency relay (81), earth fault relay (51G), reverse power relay (32), loss of field excitation relay (40), restricted earth fault relay (64) and rotor earth fault relay. The EDG status monitoring is carried locally at the EGCP in substation and from remote PMS/LV Emergency Switchboard via Serial/Hard-wired link.




The Power Management System (PMS) also has the ability to generate a synchronizing command to the EGCP for starting and synchronizing the EDG with the Emergency Bus. During parallel operation, EDG will run at fixed power mode based on the load setting programmed in EGCP which shall be as follows: Control and Operating Philosophy for EDG (323-X-002) a) Initial Status: Mains power (GTG) ON, Mains Incomer breaker of Emergency MCC ON, EDG OFF, EDG in Auto Control mode. Sequence of Operation 

In case of failure of mains power, under-voltage relay at Mains incomer of Emergency MCC will sense the under-voltage & will provide hard-wired engine ‘Start’ signal to EGCP to EDG. (in case there is under-voltage on mains supply of Emergency MCC due to tripping of incomer breaker from utility MCC, EDG start signal will be inhibited)



After build-up of EDG voltage on Emergency MCC, EGCP will provide hard-wired signal to PMS for closure of EDG Incomer breaker.



PMS will give hard-wired ‘Close’ command for closure of EDG Incomer Breaker of Emergency MCC.



EDG will continue to run in constant frequency mode.

b) Initial Status: EDG ON, Mains power OFF, EDG in Auto Control mode. Sequence of Operation 

After resumption of normal power, PMS shall give back synchronization command (hard-wired) to EGCP



EGCP will control synchronization process & mains breaker closure signal (hard-wired) will be send to PMS



PMS in turn will give hard-wire command to close mains breaker of Emergency MCC.



After synchronization of EDG with mains, EDG will run in constant power mode as per set point in EGCP. EDG power/frequency parameters are received by PMS which will be given to EGCP



Hard-wired ‘Stop’ signal from PMS will be given to EGCP for stopping the EDG.



EGCP will then slowly reduce load on EDG & give EDG incomer breaker a ‘Open’ command (hard-wired) to PMS



PMS will give EDG ‘Open’ command to open EDG incomer breaker at Emergency MCC






GCP will stop engine after preset time

c) Initial Status: Mains ON, EDG OFF Sequence of Operation 

In case GTG is overloaded & it is required to run EDG in parallel with mains, PMS will give hard-wired command to EGCP for starting of EDG



EGCP will synchronize EDG supply with normal supply



EGCP will give hard-wired signal to PMS for closing of EDG incomer breaker



PMS will give hard-wired closure command for closure of EDG Incomer breaker



After synchronization of EDG with mains, EDG will run in constant power mode as per set point in EGCP which are received by PMS via, Serial link



Further EDG stopping will be similar to procedure (b) above

d) Initial Status: Mains ON, EDG OFF Sequence of Operation 

EDG is required to run for its load test



PMS will give load test command to EGCP (Hard-wire signal)



EGCP will start engine



EGCP will give EDG breaker closing signal to PMS after synchronization conditions are achieved



PMS will give hard-wired breaker closing command to EDG Incomer breaker



EDG will run at fix load as per preset value

Manual Operation 

Engine can be started from EGCP in local mode



Manual synchronization is achieved from EGCP by speed & voltage control adjustments from EGCP



Pushbuttons on EGCP are used to give breaker CLOSE/OPEN commands. However, these breaker ‘close/open’ commands are routed to Emergency MCC via PMS

5.3

MAIN HV SWITCHBOARD

Main HV Switchboard Design Main 11 kV HV Switchboard shall receive and distribute the generated power to the entire plant. It is rated at 11 kV, ph, 50 Hz, 1600 A, 31.5 kA for 1 sec. The rating of the HV switchboard is adequate for sustained parallel operation of two generators.




The large VSDS-driven motors (MV) of the plant are fed from this switchboard. The starting of the large MV motors (Field Gas Compressor Motor rated at 7 MW for GGS) connected to this board is assisted with Variable Speed Drive Systems. The LV loads of the plant are fed through 11/0.42 kV power transformer and LV switchboards. The GTG incomer breakers and all outgoing breakers (except bus coupler breakers) of the HV switchboard are all of identical rating (1250 A) and accordingly there is flexibility of using a spare breaker in case of development of electrical or mechanical fault by any of the operation by operating breakers. Interlocks 

Every feeder in the HV switchboard is provided with earth switch at the cable side of the module. The operation of the earth switch is manual, but interlocked mechanically with the feeder breaker such that the earth switch can be closed only if the associated breaker is open.



Each of the bus section of the HV switchboard is also provided with an earth switch which is interlocked electrically & mechanically with the bus coupler breaker so that the earth switch can be closed only if the associated bus coupler breaker and other breakers in the bus section that can act as a power source to the bus are open.

5.4

POWER TRANSFORMER

Power Transformer Design The GGS plant LV loads are catered by the following transformers: Tag No. Rating Voltage Ratio Type Impedance Transformer X/R ratio Off circuit Tap Changers In-rush Current

: : : : : : : :

332-TML-1-1A/1B 2500 kVA 11 kV/0.420 kV Dyn11, ONAN, 3 phase, 50 Hz 7.45% with no negative tolerance 9.2 (approximate) ± 5% in steps of 2.5% ≤ 5 X Rated Current

Tag No Rating Voltage Ratio Type Impedance Transformer X/R ratio No Load Tap Changers In-rush Current

: : : : : : : :

323-TML-1-3A/3B 1600 kVA 11 kV/0.420 kV Dyn11, ONAN, 3 Phase, 50Hz 6.33% 6.17 (Approximate) ± 5% in steps of 2.5% ≤ 5 X Rated Current




100% redundancy has been considered for arriving at the rating of the Power Transformers. The transformers are operating continuously and each is loaded 50% during normal operation. The Well head loads are catered by the following step-up transformers which are located in GGS. Tag No.

:

Rating Voltage Ratio Type Impedance Off Circuit Tap Changers

: : : : :

323-TML-1-3, 323-TML-1-4, 323-TML-1-5, 323-TML-1-6, 323-TML-1-7, 323-TML-1-10, 323-TML-1-11 75 kVA 0.4 kV/3.45 kV dYN1, ONAN, 3 Phase, 50 Hz 3.79% ± 5% steps of 2.5%

The loads at Well head are catered through PDB by the following step-down transformers located at the Well heads. Tag No.

:

Rating Voltage Ratio Type Impedance Off Circuit Tap Changers

: : : : :

5.5

101-TML-1-1, 103-TML-1-1, 108-TML-1-1, 109-TML-1-1, 110-TML-1-1, 106-TML-1-1, 107-TML-1-1 75 kVA 3.3 KV/0.420 kV dYN1, ONAN, 3 Phase, 50 Hz 3.77% ± 5% steps of 2.5%

LV POWER DISTRIBUTION

LV Switchboard Design The Ebla LV three phase distribution system voltage has been selected as 400 V. The LV loads to be fed from each substation has been classified as Utility Loads, Process Loads and Emergency Loads and accordingly each of the Plants has been provided with a Utility Switchboard, Process Switchboard and an Emergency Switchboard. The incomer details and the rating of these switchboards at GGS are as follows: o

The 400V Utility MCC (323-MCC-1-1) is fed by two incoming lines, feeders from two nos. 11/0.420 kV, 2500 kVA distribution transformers (i.e., 323-TML-1-1A and 323-TML-1-1B). The switchboard consists of two incomers and a bus-coupler and various outgoing motor feeders and bulk power feeders. The rating of the switchboard is 4000 A, 400 V, 3 Phase + Neutral, 4 Wire, 50 Hz, 80 kA for 1 sec.

o

The 400 V Process MCC (323-MCC-1-3) is fed by two incoming feeder from two nos. 11/0.420 kV, 1600 kVA distribution transformers (i.e. 323TML-1-3A and 323-TML-1-3B). The switchboard consists of two incomers




and a bus coupler and various outgoing motor feeders, heater feeders and bulk power feeders. The rating of the switchboard is 2500 A, 400 V, 3 Phase + Neutral, 4 Wire, 50 Hz, 50 kA for 1 sec.

o The 400 V Emergency MCC (323-MCC-1-2) is fed by two incoming feeders, one from the 400 V Utility MCC (323-MCC-1-1) and second from 1200 kW Emergency DG Set. The rating of the switchboard is 3000 A, 400 V, 3 Phase + Neutral, 4 Wire, 50 Hz, 80 kA for 1 sec. The LV switchboards are totally enclosed, metal clad, free standing, double front semidraw-out type with ACBs for incomers and bus-couplers and MCCB/SFU for outgoing motor/bulk power feeders. The LV normal switchboards are rated to carry the full load current of one of its feeding power transformer. The short circuit ratings of the switchboard and impedance value of the power transformer have been adequately selected for isolated operation of two power transformers connected to the switchboard. The emergency switchboard is rated to cater to the connected emergency loads. The PMS shall carry out the following control and status-monitoring functions with respect to the LV switchboard: o

Closing/opening of all LV incoming, bus coupler, outgoing ACB feeders.

o

Closing/opening of all LV motor breakers, heater feeders without Thyristor Control Panels based on the command from ICSS.

o

Measurement of all important electrical system parameters including:

a) Ampere, kW, frequency of the LV switchboard incomer b) Ampere, Bus Voltage, Bus Frequency for LV Bus Tie c) Ampere, Bus Voltage, Bus Frequency for outgoing ACB feeders d) kW for Motor Feeders and Heater feeders without Thyristor Control Panels 1.Monitoring of the fault status from the output of intelligent relays provided in the LV switchboard. 2.Recording and reporting of Sequence of Events (SOE) of feeders including motor feeders and Incomer Feeders following a trip. 3.Transmitting of all outgoing motor feeder contactor and fault status (as required) to the ICSS Control supply for the switchboard incomer, bus coupler & outgoing breaker feeders is derived from the respective substation 110 V DC UPS panel. Interlocks 

Inter trip of the LV breaker on tripping of HV breaker is provided.






Interlock between incomer and bus-coupler breakers to ensure Two-Out of Three breakers remain closed at any point of time, with provision to defeat the interlock during momentary paralleling of incomers.



Slow bus transfer scheme/Auto change over scheme along with momentary paralleling scheme between incomers and bus coupler breaker of utility & process MCC has been provided for transfer of power from one incomer to other during failure of power to any one of the supplies.

Distribution Boards for Lighting, HVAC, Heat Tracing & Cathodic Protection Separate conventional type distribution boards will cater to the power requirement for lighting and small power system, HVAC system, Heat Tracing System and Cathodic Protection System. The above distribution boards shall be controlled from the switchboard only. 400 V/230 V AC UPS System Two numbers of 50 Hz, equally rated, physically & electrically separate UPS systems each with its own battery is provided in the substation to cater to each of the following loads (which includes DCS and PMS power supplies): (a) Individual Instrument load supplies – 400V, 3 Phase UPS (b) Telecommunication load supplies – 230V, 1 Phase UPS The UPS units will operate independently for supplying power to the load. The neutral of each of the UPS system is solidly earthed. The rating of the Instrument Supplies AC UPS is 60 kVA (GGS) each with UPS battery backup duration of 6 hours. The rating of the Telecom AC UPS is 4 kVA with UPS battery backup duration of 8 hours. Incoming supply to the UPS is provided from the Emergency MCC and the bypass supply provided from normal switchboard. Static Switches in the UPS ensure uninterrupted and synchronized switchover from UPS supply to bypass in the event of mains failure or inverter/rectifier failure of UPS. The 230 V AC UPS supply for telecom loads is distributed to the loads through conventional 230 V, 50 Hz, 1 phase distribution boards with MCCB incomer feeders and MCB outgoing feeders. The 230 V AC UPS supply for Instrumentation loads is derived from 400 V, 50 Hz, 3 phase distribution boards with MCCB as incomer feeders and MCCB outgoing feeders. The 400 V and 230 V AC UPS distribution boards are located at the substation. Provision of receiving redundant UPS supply is made in all critical loads.






6.0

INSTRUMENTATION



6.1



INTEGRATED CONTROL AND SAFETY SYSTEM (ICSS)

ICSS of GGS consists of the following elements: o

DCS

o

ESD

o

F&G

o

RTU (Remote Terminal Unit), Remote I/O and SCADA for Well heads

o

ESD Matrix

o

Fire & Gas Matrix

o

Operator Work Stations

o

Engineering/Maintenance Work Stations

o

Historian

o

Plant Management System and

o

Management Information System

Communication between Well heads and GGS, and communication between GGS and GTP are through the single mode fibre optic cables. To increase the reliability of communication, redundant fibre optic cables are used. 6.2

Distributed Control System (DCS) – GGS

The HIS in the Gas Gathering Control room (GGCR) at GGS provides operator access for all parts GGS. DCS, ESD, and F & G system for the GGS located in Instrument Equipment Room (IER) connected by the Vnet/IP and Ethernet LAN. Engineering workstations for the DCS and SCS is provided for development and configuration. The GGS control building is divided in to three areas depending on the location of ICSS equipment. 1. Gas Gathering Control Room (GGCR) 2. Engineering & Maintenance Room 3. Instrument Equipment Room (IER) Gas Gathering control room is the principle location for the plant personnel to perform Plant operations. For GGS, Gas Gathering control room (GGCR) is normally for process information presentation, process operation, Control and monitoring and Maintenance by operation personnel responsible for plant operation. The control Room house the operator consoles with operator stations and emergency control facilities. Human interface stations, ESD console, FGS Panel, and are mounted in GGCR. Engineering & Maintenance Room houses the following stations and printers: o

ENG/SENG station (Dual screen)

o

PRM (FDM) Station



SIOS station

o

Master file server


o Color laser A3 printer – 5 Nos. o

Laser printer.

Instrument Equipment Room (IER) houses the DCS, ESD and FGS system and marshalling cabinets. IER also contains the ICSS sub systems necessary to interface with the package controls and local field devices. The Human Interface Station (HIS) is mainly used for operation and monitoring. It displays process variables, control parameters and alarms necessary for the operator to have quick knowledge of the operation status of the process. It also incorporates open interfaces so that supervisory computers and workstations can access trend data, messages and other process data. The Engineering station has all the feature of an HIS and also can provide engineering functions such as system generation, Maintenance and test solutions. Plant resource Manager (PRM) is provided to enhance the efficiency of the management and maintenance of field devices that are registered and assigned to plant hierarchy. Also, it automatically creates documents on devices so that they can be managed electronically. The SIOS sits on the Vnet/IP Network. In operation integration, a SIOS (System Integration OPC Station) is used to connect FCN controllers to a CS3000. DCS has redundancies in the following levels: o

Processor

o

Power supply

o

Communication with ESD and F &G subsystems

o

Communication with UCP for major package units

Ultra high resolution 21” duel LCD monitors are used as Operator Work Stations. GGS has two dual screen operator workstations. One single screen ultra high resolution 21” LCD monitor is used as engineering workstation in GGS. One fascia of Fire & Gas Matrix and one fascia for ESD Matrix are present in the GGS control room. One number of Alarm and Event Printer, one number A3-size colour printer for Engineering Work Station, One number of A3 size colour printer as Historian printer and one A3 size colour printer for general report printing are also provided.




Package units are connected to the DCS through Modbus serial link communication bus. This link is redundant for some of the important packages like power generation package and field gas compression package.




Fig. 8 – Overall Control System Architecture – GGS




DCS I/O and control function is developed around Foundation Fieldbus (FF) technology. Foundation Fieldbus transmitters were connected to the DCS through FF barriers which are located in field. Power supply to FF transmitters is redundant. Conventional 4 to 20 mA analog inputs and outputs are hard-wired to the DCS via conventional I/O cards. Similarly digital I/Os are directly hard-wired to the DCS. DCS has separate cabinets for segregation and termination of Fieldbus and conventional instruments. Motor Control Centre (MCC) is connected to DCS via two-way redundant Modbus serial link cable. This cable carries control commands from DCS to the MCC switchgear panels and status of electrical equipment and electrical data to MCC. Hard-wired are also used between these two panels. From main trunk line maximum 10 spurs can be connected. Separate marshalling cabinets are provided for FF and conventional I/Os of DCS. The data from GGS is communicated to GTP through redundant fibre optic cables. ICSS system will be interfaced to GPS clock for the synchronization. For communication with package units, the following packages are provided with redundant Modbus serial link communication cables: o

Field gas compressors

o

Main power generators

Non-redundant Modbus link is provided to the following packages: o

Instrument air compressor

o

Instrument air dryer

o

HVAC systems

o

Nitrogen generation units

At well-sites, a RTU with Hot standby CPU and simplex IOs is included in the Well head control panel (WHCP) which will provide monitoring and control of WHCP functions and choke. Well RTU is lined via fibre optic cable to a SCADA unit in GGS. DCS interfaces with electrical switchgear and PMS via remote PLCs. PLCs will send information such as breaker status, load shed alarms and load information to DCS via serial link. Package units are connected to the DCS through Modbus serial link communication bus. This link is redundant for some of the important packages like power generation package and Stabiliser compressor package. DCS I/O and control function is developed around Foundation Fieldbus technology. Foundation Fieldbus transmitters are connected to the DCS through FF barriers which are located in field. Power supply to FF transmitters is redundant power supply. Conventional 4 to 20 mA analog inputs and outputs are hard-wired to the DCS via conventional I/O cards. Similarly digital I/Os are directly hard-wired to the DCS. DCS has separate cabinets for segregation and termination of Fieldbus and conventional instruments. Separate marshalling cabinets are provided for FF and conventional I/Os of DCS.




From main trunk line, maximum 10 spurs can be connected. The data from GTP is communicated to GGS through redundant fibre optic cables. DCS interfaces with electrical switchgear and PMS via remote PLCs. PLCs will send information such as breaker status, load shed alarms and load information to DCS via Modbus serial link. Hard-wired connections are also used between these two panels. ICSS system will be interfaced to GPS clock for the synchronization. For communication with package units, the following packages are provided with redundant Modbus serial link communication cables: o

Main Power Generators GTG

o

Stabiliser Compressors

o

Expander

o

Sales gas compressors

o

De Ethanizer compressors

Non-redundant Modbus link is provided to the following packages: o

Instrument air compressors

o

Instrument air dryer

o

HVAC systems

o

nitrogen generation units

MIS interface with fire wall protection is provided to enable remote monitoring, long term trending and report generation functionality. High reliability fault tolerant Ethernet communication network (ICSS LAN) is provided on the facility to enable the integration of various sub systems. For Start up of DCS refer the following Document: Vendor Project Doc. No. Vendor Doc. No. cument Title 6.3

: YOKOGAWA Engineering Middle east FZE : JI-190-030026-EIN-M03-001 – Rev A : PHG-J01-IM-002 – Rev A : DCS Instruction Manual

EMERGENCY SHUTDOWN SYSTEM (ESD) – GGS

It is part of ICSS system. A single common ESD system in GGS covers all the units of GGS. ESD system is designed with the criteria of personnel safety, minimum pollutant release to the environment, minimizing spurious plant shutdowns and protection of plant equipment. ESD system has been designed incorporating the SIL (Safety Integrity Level) analysis. SIL analysis includes personnel safety integrity analysis, AIS (Asset Integrity Level) analysis such as loss due to damage and loss of production analysis, and, EIL (Environmental Integrity Level) analysis such as release of pollutants in the environment. The ESD system objectives are: Controlled shutdown of machinery and other equipment; separation of pipe work and equipment by means of isolating valves; and, blowdown of gaseous hydrocarbons to the flare system as required.




Shutdown is categorized into three levels, as follows: o

ESD Level 1 – Total facility shutdown with Auto depressurization.

o

ESD Level 2 – Total Process shutdown with depressurization enabled, but operator has to initiate depressurization.

o

ESD Level 3 – Unit Process shutdown/individual equipment shutdown with depressurization as necessary.

ESD system is essential to the overall safety of the facility and so can act independent of other systems. ESD system will sense any abnormal operation or equipment condition and react to this condition by safely shutting down and or isolating the facility or sections of the facility to reduce the effects of abnormal condition. On severe condition, the system will depressurize the entire facility process systems or sections of these systems either automatically or manually. ESD system cabinet is located in the equipment rooms in the GGS control building. To have the highest reliability, the ESD system is designed with redundancies at Processor level, I/O level and power supply level. Redundant communication cables are provided to communicate with DCS. Communication to DCS is through the high speed Ethernet cables. Process over-ride switches and Maintenance over-ride switches are provided in DCS as soft switches. All analog transmitters connected to the ESD system are conventional type (not FF type) and are directly hard-wired to the system. Since ESD system needs the highest reliability, direct hard-wire connected 2-wire transmitters are used. Similarly all the digital inputs and digital outputs connected to the system are hardwired. ESD system receives signals from Package unit UCPs, directly from package units and main process units. Output from ESD system to the F&G system and inputs from F&G systems to EDS system are hard-wired between the panels. An ESD matrix panel is located in between the operator work stations. This panel contains the indications about the ESD initiators, switches for ESD reset, and unit-wise ESD initiating switch. ESD Operated On/Off Shutdown and Blow down Valves These are solenoid operated On/Off valves that are controlled by the ESD and shall be operated in accordance with the ESD Cause & Effect logic. ESD outputs are normally energized. The ESD repeats the valve demand signal to the DCS to enable the valve traveling & discrepancy alarming functions to operate in the DCS & to synchronize logic.




Fig. 9 – ESD Initiated Air Operated Blowdown Valve with Status Single Acting/Spring Return

The Function of this loop is to control the ON/OFF valve from DCS through ESD. The Serial DO signal of the ON/OFF valve is connected to ESD through soft signal. Example: Consider the Production Separator (302-V-001) Blow down valve 302-XV-1104 mounted on the Separator to Flare header line (Line no. 10’-302-PG-1007-36A-N). The Serial output signals (SDO) 302-XHSL-1104 & 302-XHSH-1104 are configured in the DCS as Manual switches to initiate BDV Close & Open Commands respectively. The Operator manipulates the ON/OFF valve status change command from the SIO block faceplate displayed on DCS HMI using a computer point device such as mouse The Operator or the automatic control logic written in the ESD can change the ON/OFF valve status. This configuration of the Shut down valve control means that manual control from the DCS cannot override ESD demands from the ESD system. The Full automatic plant depressurizing only occurs as a result of ESD1. ESD Level 2 enables the blowdown valves which provide the operator with an option for Blowdown. The List of Blowdown Valves:



Item Description 302–XV-1104 SEP TO FLR BDV 302–XV-1150 CNDST CLSR BDV 304–XV-1264 FLGS CMP-A BDV 304–XV-1364 FLGS CMP-B BDV 305–XV-3000 GS DEHYD COL BDV 321–XV-3300 FUEL GAS KOD BDV DCS Operated On/Off Valves


P & ID 302-EPR-PID-03101-001 302-EPR-PID-03104-001 304-EPR-PID-03112-001 304-EPR-PID-03115-001 305-EPR-PID-03121-001 321-EPR-PID-03211-002

These are solenoid operated on/off valves controlled by the DCS and have no control from ESD. These shall be operated in accordance with the DCS logic when in AUTO and as per operator command when in MANUAL. Fig. 10 – DCS Initiated Air Operated ON/OFF Valve with Status Single Acting/ Spring Return




ESD & DCS Operated On/Off Valves ESD & DCS valves have two SOVs, one wired to ESD & the other wired to the DCS, pneumatically connected in series; when any one of the ESDs trip or DCS interlock is active, the valve goes to its fail-safe position. Fig. 11 – ESD Initiated Air Operated Shutdown Valve with Status Single Acting/ Spring Return

The Function of this loop is to control the On/Off valve through the DCS. The DO signal of the ON/OFF valve is directly wired to DCS. The operator or the automatic control logic can change the ON/OFF valve status. Example: Consider the Field Gas Compressor Package (304-X-001A) Blow down valve 304-XV-1264 mounted on the Discharge line to Flare header line (Line No. 3’’-304-PG-1019-16A-P). The Serial output signals (SDO) 302-XHSL-1264 & 302-XHSH-1264 are configured in the DCS as Manual switches to initiate BDV Close & Open Commands respectively. The Operator manipulates the ON/OFF valve status change command from the SIO block faceplate displayed on DCS HMI using a computer point device such as mouse. The Operator or the automatic control logic written can change the ON/OFF valve status.




The valve opens when the ESD trip is cleared, logic is reset & the DCS interlock is not active. List of ESD & DCS Operated On/Off Valves Item 304–XV-1264 304–XV-1364 302–XV-1157 304–XV-1200 304–XV-1201 304–XV-1300 304–XV-1301 701–XV-3160 304–XV-1286

Description FLGS CMP-A BDV FLGS CMP-B BDV PRD SEP I/L BALL FLGS KODA I/L VLV FLGS KODA I/L VLV FLGS KODB I/L VLV FLGS KODB I/L VLV FG HTR I/L VLV GAS HYDRN I/L VLV

P&ID 304-EPR-PID-03112-001 302-EPR-PID-03115-001 304-EPR-PID-03101-001 304-EPR-PID-03111-001 304-EPR-PID-03111-001 304-EPR-PID-03114-001 304-EPR-PID-03114-001 701-EPR-PID-03401-001 304-EPR-PID-03111-001




Double Isolation Valves Double isolation valves are placed parallel to each other in the pipe. After the ESD trip causes are cleared and the operator resets the logic, the operator shall open the bypass valve manually through HMI to gradually pressurize the down-stream system. Fig. 12 – Double Isolation Valves (ESD Initiated Air Operated Shutdown Valve)




The main valve is inhibited from opening until the differential pressure (DP) across the valve is higher than the set point. Opening the bypass valve will bring down the DP across the valve. The main valve will open automatically once the DP falls below the set point. Double Isolation Valves List Main Valve Tag No. 302-XV-1100 304-XV-1267 304-XV-1200 304-XV-1300

Bypass Valve Tag No. 302-XV- 1157 304-XV- 1286 304-XV- 1201 304-XV- 1301

PDT Tag No. 302-PDT-1107 304-PDT-1266 304-PDT-1206 304-PDT-1306

P&ID 302-EPR-PID-03101-001 304-EPR-PID-03111-001 304-EPR-PID-03111-001 304-EPR-PID-03114-001

Testing of On/Off Valve locally at the Valve via the ESD System This test shall be carried out on ESD valves that have a local test station. The local test station comprises a test/manual bleed point, key-operated local solenoid over-ride valve, trip & reset pushbuttons. The key-operated local solenoid over-ride valve allows operation of the ESD & DCS solenoid valves without tripping the actuated valve. This is achieved by sealing in the air pressure within the actuator. The over-ride can only be applied with the key and with over-ride valve held in the test position. o

Test gauge is screwed into test point.

o

The trip over-ride valve is un-locked.

o

The trip over-ride valve is depressed & held in the over-ride position.

o

The field trip pushbutton is depressed and input signal sent to the ESD to trip the valve.

o

The ESD de-energizes its output and switches the respective solenoid to vent.

o

The ICSS system shall annunciate valve in local test on the HMI screen/alarm banner.

o

The ICSS shall inhibit valve limit switch feedback discrepancy logic since the actuated valve will not trip.

o

The operator conducting the test shall verify that the solenoid vents the air pressure.

o

The field reset pushbutton is depressed and input signal sent to the ESD to reset the valve.

o

Valve in Local test shall be removed from the HMI screen.


o



The ESD re-energizes its output and switches the respective solenoid to supply air.

o

The operator verifies that the air pressure is restored.

o

The trip over-ride valve is released and key removed (if not already done).

o

The test gauge is removed and the test point is resealed.



7.0

FIRE AND GAS



7.1



FIRE & GAS – INTRODUCTION

Fire & Gas system is part of the ICSS. The plant F&G detectors are directly hard-wired to the F&G cabinet located inside the equipment room of the control building. Building F&G detectors are connected to the Building Fire Alarm panel (BFA). These BFA panels communicate with the main F&G panel via Modbus serial link. Inputs from package units are also hard-wired to the F&G panel. Outputs from F&G system such as Confirmed Fire and Confirmed Gas Leak are hard-wired to ESD system. F&G output to ESD system will initiate ESD-1 or ESD-2 of a unit depending on criticality. For details refer the F&G Cause & Effect diagrams of GGS & Well heads/GTP. Operator interface to the F&G system is through the operator console in DCS. It will display the status and any alarm signal from the F&G devices. A Fire & Gas Matrix panel located in the GTP control room acts as an alternate/emergency operator interface for the F&G element. The Matrix panel provides indication of the following for each fire zone: o

F&G status indication (Green LED ON when F&G system is healthy in a zone)

o

MAC actuated indication (Red LED ON when MAC actuated in a zone)

o

Fire detection indication (Amber LED ON when a fire detector senses fire)

o

Combustible gas detection indication (Blue LED ON when a gas detector senses combustible gas leak)

o

Toxic Gas detection indication (Yellow LED ON when a gas detector senses combustible gas leak)

o

Inhibit enabled indication (White LED ON when an input inhibited in a fire zone)

F&G matrix panel also has facilities to start fire water pump {GTP} and to select duty/standby pump. Pushbuttons are available to manually initiate fire alarm, pushbuttons to acknowledge, silence F&G alarms, lamp test and F&G system reset. Input inhibit on F&G system can be done from F&G matrix panel at control room by the control room operator using permissive zone key switch. Fire & Gas system is separate for GGS and GTP. Data transfer between GTP and GGS F&G systems is through fibre optic cable. The following types of Detectors are used: o

Flammable Gas detectors

o

Toxic Gas Detector (Only in GTP)

o

Flame detectors



Smoke detectors

o

Heat detectors

o

HSSD


Alert Instruments o

Beacons/Lamps

o

Sounders

7.2

FIRE DETECTORS

o

Flammable Gas Detectors (DFR) are Infra Red (IR) type

o

Flame Detectors (DFR) are Infra Red radiation type or UV type. In some places fusible plugs are also used as flame detectors

o

Heat detectors (ROR) are used inside buildings in non-hazardous area only and they are ‘rate of rise’ semiconductor type

The following are the gas detectors used: o

Toxic Gas Detectors (DGT) are semiconductor type and are installed only in GTP

o

One type of hydrocarbon detectors is Open Path type hydrocarbon gas detectors (DGOR/DGOT). This has a transmitter and receiver type arrangement to detect gas leak

o

Hydrocarbon is also detected by IR type point detectors (DGP)

o

Hydrogen detectors (DGH) are used to detect hydrogen gas alone

o

Smoke detectors are optical type and used in non-hazardous area only

o

HSSD is the High Sensitive Smoke Detection system used in buildings to detect the fire at an early stage

7.3 o

ALERTING EQUIPMENT Beacons (DAL) are the lamps for alerting the personnel in case of fire or gas leak. Red lamp is to indicate Fire. Yellow lamp is to indicate Gas leak

o

Manual fire Alarm call points (DMC) to initiate Fire Alert Sounders (DAS) are dual tone type. It sounds in different tones, during fire and gas leak. These dual tone sounders are mainly used in plant area only. Fire alarm bells are used for the buildings

o

The Following fixed pre-set tones are programmed in to the Sounders:



1.

Sweep 1200 – 500 Hz at 1 Hz for Toxic Gas

2.

Int 660 1.8 sec on 1.8 sec off for Fire and Gas

3.

Continuous 660 Hz for Evacuate alarm


On actuation of the Manual Call Point, the following actions are envisaged: o

A Zone alarm & a common Confirmed Fire alarm are indicated at the matrix panel and ICSS

o

Also a common alarm is generated in ICSS and displayed in graphic display; the event is recorded

o

A Local Visual & Audible alarm is initiated

o

A Confirmed Fire signal is sent to ESD1

If the detector is at fault, the event is printed and displayed in the graphic display. Also a detector fault common alarm is sounded in ICSS. In the case of IR3 type flame detection, 2oo3 Voting is carried out. A single IR3 Flame detector signal initiates the following actions: o

A fire alarm is indicated at the matrix panel and ICSS

o


2oo3 Voted (High) signal initiates the following actions: o

Confirmed fire alarm at the Matrix panel/ICSS

o

A common alarm is displayed at ICSS and a visual alarm is initiated locally

o

A Confirmed Fire signal is sent to ESD1

If the detector is at fault, the event is printed and displayed in the graphic display. Also a detector fault common alarm is sounded in ICSS. The single flammable gas detector (LOS) signal initiates the following actions: o

A flammable gas Low alarm/Confirmed Flammable Gas High alarm is indicated at the matrix panel and ICSS

o

A common alarm is generated in ICSS and displayed in graphic display; the event is recorded

If Voted (High), the signal initiates the following actions: o

Confirmed Flammable Gas High alarm at the Matrix panel/ICSS

o


o

A confirmed 20% LEL/3LFLM Gas signal is sent to ESD1


o



If the detector is at fault, the event is printed and displayed in the graphic display; also, a detector fault common alarm is sounded in ICSS

The single Hydrogen Gas detector/Point type flammable gas detection signal initiates the following actions: o

A Flammable Gas Low alarm is indicated at the matrix panel and ICSS in the case of 10% LEL

o

A Confirmed Flammable Gas High alarm is indicated at the matrix panel and ICSS in the case of 20% LEL

o


If Voted (High) the signal initiates the following actions: o

Confirmed Flammable Gas High alarm at the Matrix panel/ICSS

o


o

A confirmed 20% LEL/3LFLM Gas signal is sent to ESD1

If the detector is at fault the event is printed and displayed in the graphic display. Also a detector fault common alarm is sounded in ICSS. Refer Fire & Gas System Cause & Effect Diagram (GGS) (300-EHS-CNE-002).


7.4



FIRE ZONES

GGS is divided in to 14 fire zones. Well heads are divided in to 5 fire zones and GTP is divided in to 15 fire zones. Fire Zones in GGS Fire Zone

Description

300-01 Common Gate House/ 300-02 Accommodation Diesel Storage/ 300-03 Methanol Storage 300-04 Methanol Injection 300-05 Ware House/Workshop 300-06 Main CCR 300-07 Substations 300-08 Power Generators Potable/Utility Water/ 300-09 Plant Instrument Air/N2 Oily Water/ 300-10 Open Drain System 300-11 Gas Inlet Facilities Separator/Fuel Gas 300-12 System/Cooler Compressor Area/ 300-13 Dehydration Area 300-14 Flare Area Total

Flame Detection IR 3

HC Gas HC Gas HC Gas Point Open Hydrogen Heat Smoke Point Detectors, Path Detector Detector Detector Detectors Duct-Mounted Detectors

Manual Alarm Call Point

HSSD

9 3

35

14

3

4 2 2

2 2

2 2

4 10

9 7 8

2

1 3 3 5 1

3 1 1 1 1

1

2

1

1

7

4

22

1

4

3

14

3

3 39

0 19

4 40

1 57

17

59

1

1

2

4

1

2 3 2 1

1

8

4

1

4 1

3

Local Local Audible Pneumatic Visual Alarm Sounder Alarm Sounder Beacon

1 1

1 2

2

2

1 12

4 1

20




In well heads, the fire and gas detectors are connected to the local RTUs which communicate the status of detectors to GGS via fibre optic cable. Confirmed Fire is assumed as a result of any of the following in any single fire zone: o

Simultaneous actuation of a minimum of two flame detectors

o

Simultaneous actuation of a minimum of two smoke detectors

o

Simultaneous actuation of a minimum of two heat detectors

o

Actuation of one fusible bulb or frangible bulb

o

Actuation of one Manual Call Point

Confirmed Gas Leak is assumed when any two gas detectors from a single fire zone gets actuated. When any two gas detectors get actuated at 10% LEL (low level alarm), then it is called confirmed low gas leak. When any two gas detectors get actuated at 20% LEL (high level alarm), then it is called confirmed high gas leak. On confirmed detection of fire or gas, the F&G system will initiate executive action such as release of extinguishant , fire damper control, electrical isolation, fire water control or shutdown. Executive action shall be initiated manually also. When electrical isolation is performed as part of executive action, power to the following equipment is not disturbed: o

Emergency lighting within building and plant

o

Emergency communication equipment such as radio and telephone

o

Fire & Gas system

o

Ignition panel of Flare package

o

ICSS in the control room

o

Control room and Substation building HVAC systems

On failure of power, UPS power will be supplied to these equipment. Well head and GGS Fire & Gas System is connected to the ICSS in GGS. Well-sites have RTU based system that will carry out all necessary functions and interface with the ICSS via SCADA unit located in the GGCR to allow monitoring and safety executive actions. The following page shows a tabulation of the fire zones in GGS. 7.5

HIGH-SENSITIVE SMOKE DETECTION SYSTEM (HSSD)

The HSSD system is an addressable system in which each fire zone, fire detector and smoke detector can be addressed independently. HSSD is the High Sensitivity Smoke Detection System located inside buildings of non-process area only. This is of aspirator type, so it has a pump for suction of smoke along with air from different corners of the building. The system aspirator pipeline is designed in such a way that the air through the farthest point will not be less than 70% of that of the nearest point and the time taken




by the air to travel to the detector unit from the farthest sampling point will be less than 120 sec. The HSSD system has a battery backup. The system is capable of detecting the incipient fire by detecting the air-borne particles generated during pre-combustion stage. It consists of an aspirating pump with balanced air sampling pipe network to transport air to the detection unit, a particle knockout and particle counting unit. The system has a laser-based smoke detection unit. The system communicates with the ICSS system via dual redundant data links. The HSSD system is programmable for: o

Smoke alarms

o

Alarm delays

o

Relay output for remote indication and system faults

o

Fault levels for airflow, detector monitoring and power failure etc.

o

Viewing the status of any device in the system

o

Recording an event log for later use

o

Aspirator pump speed control

o

Maintenance interval programming

o

Air flow supervision with High and Low flow fault setting

o

Sensitivity adjustment of individual detectors

The aspirator pump, detector unit etc are housed inside the wall-mounted panel of the HSSD system. The system has built-in facility to store event logging, smoke alarms and system alarms. The HSSD panel has the following features: o

Field programmable alarm with corresponding output relays

o

Adjustable time delay for alarm threshold

o

Lights and audible test

o

Reset capability

o

Fire zone isolation

o

Test, isolate and reset from panel switches

o

Over-rides of outputs

Building fire alarm system is installed in GGS in the following locations: o

Control room building

o

Substation building

o

Warehouse & workshop building

o

Accommodation & Gatehouse buildings




Accommodation and Gatehouse have separate HSSD systems. Control room and substation have individual HSSD systems. The HSSD system panels have indication to show the status of detectors. They will transmit information to the F&G element of the ICSS via dual redundant data links.



8.0

TELECOMMUNICATION



8.1



TELECOM SUBSYSTEMS

The Permanent Telecommunication Network consists of following telecommunication subsystems and infrastructures: o

Fibre Optic Cable (FOC) for intra- and inter-plant connectivity

o

Fibre Optic Transmission System (SDH) to provide voice, video, data and telemetry signalling transmission among various sites

o

Telephone System for General Voice Communication among various sites

o

UHF Trunk Radio System for Plant/Field Area Mobile Communication

o

Radio Tower for mounting radio antennas

o

Environment

Monitoring

System

for

monitoring

critical

weather

parameters o

Data Network – LAN/WAN

o

Entertainment System for distribution of audio/video programs

o

Telecom Supervisory System for supervision of all telecom subsystems at a centralized location

o

Power Supply System for reliable power supply to all the telecom subsystems

42-core, single mode (SM) redundant Fibre Optic Cable is installed between GTP and GGS. 24-core SM redundant FOC are installed on separate routes between GGS and well heads. At both ends, the FOCs are terminated on suitable Optical Distribution Frames (ODF)/Fibre Optic Patch Panel (FOPP). In ODF, fibre terminations are sealed to prevent entry of dust or other contaminants into the fibre end. Reliable, fault-tolerant fibre optic transmission network telecommunication services between GTP & GGS are provided. The system is designed to carry a variety of telecommunications protocols such as TCP/IP and Ethernet. The system is designed to give alarm, critical system functions and pending faults. Following are the data communication equipment and ancillary equipment: o

SDH transmission/multiplexing equipment

o

Ethernet switches

o

Media converters (for well head communication)

o

Equipment enclosures

o

Miscellaneous wire, cable, connectors and mounting hardware


8.2



SDH TRANSMISSION SYSTEM

The SDH transmission system is based on 155 MBPS, STM-1 Multiplexer. Dual redundant STM multiplexers (one each) are provided at GTP, GGS. The system contains two optical transceiver cards to provide redundant transmission path in the event of a fibre break or laser failure. Dual redundant load-sharing power supply cards provided for the sub-rack, which contains dual redundant controller cards in order to provide true 1+1 protection. The following services are extended to GGS through SDH Network: o

Ethernet channels for Data Networks and WAN/LAN

o

1 x 2 Mbps channel for Trunk Radio System between GGS & GTP

o

Subscriber voice channels extended from the GTP PABX

o

Other services like Alarms, Engineering Order Wire and Supervisory Services

FO Patch Panel FO patch panels are provided at well-sites for transmission of telemetry signals of control & instrumentation to GGS through the FO cable (24 Fibre FOPP per well-site). The FOPP are mounted in instrumentation panels at the well-site. At GGS, the FOPP shall be provided in a 42-RU cabinet within the Telecom Equipment Room. Media converters are used to convert the signals from FOPP to electrical form. Synchronization Plan The SDH network; Pipeline Monitoring System (PMS) & DCS are synchronised with the GPS clock. This synchronisation is to ensure network stability and correct event-logging of plant systems. 8.3

TELEPHONE SYSTEM

The new telephone system equipment (PABX) is located in the GTP- TER which will provide telephone service within plant areas. Telephone network, including telephone sets, are provided for other sites as remote/extended subscribers through FO transmission system. Digital PABX has PCM time-division switching, central control with dual microprocessor and stored program on flash memory, redundant CPU & full redundancy for major parts & power supply. A supervisory system PC for operation, maintenance & programming of PABX is also provided. The system scan supports both Analogue Lines and Digital Lines. 8.3.1 Telephones Normal telephones are provided in offices. Weatherproof telephones are provided in external safe areas. In hazardous areas, explosion0-proof telephones certified for use in Zone 1 IIB T3 area are provided.


8.4



RADIO SYSTEM

Trunk Radio System (UHF) Base Stations are provided one each at GTP & GGS. Trunked mobile radio systems are used for voice communication between IS (Intrinsically Safe) hand portable radios, vehicle mounted radios and CCR. The base station is provided with a capacity of five (5) channels. One channel is used as control channel and the remaining four (4) channels shall be used as traffic channels. Field radios can be programmed to operate on all the frequencies allocated for all talk-groups. All the talk-groups are user-selectable. Each radio shall be able to operate either in talk-group or private call. Trunked mobile radio systems consist of Base Stations, Fixed Radios, self-supported towers, antennas, Feeder Cable and Accessories. There are twenty mobile radios (including GTP & GGS) with accessories installed in Company vehicles and seventy intrinsically-safe hand- portable radio sets, (including GTP & GGS) with accessories. The antennas are mounted on 45 m tall radio towers at appropriate height to give the required coverage. This is powered from Telecom UPS (230 V ± 1%, 50 Hz ± 5% AC supply). 230 V AC multi-chargers are provided for charging hand-held radios. These chargers are installed in Control Building. 8.4.1 Radio Tower The towers are located in GTP and GGS and has a height of 45 m. These are selfsupporting (SS) type towers, 45 m with UHF Trunk Radio systems. Hot dip galvanized steel is used for tower construction and painted with aircraft warning paint (red and white strips). The towers have rest platform and work platforms at various levels. A lightening rod is provided on the tower top to protect antennas by maintaining the antennas within 45 protection cone. The towers are bonded to the grounding system, which has grounding resistance less than 10 ohms. Aircraft warning lights are also provided on the towers. 8.5

ENVIRONMENTAL MONITORING SYSTEM

Meteorological systems are provided at GTP and GGS for weather monitoring purpose. The weather package shall comprise a server based data gathering system that will collect and display instantaneous, average and trend analysis of data received from sensors located in the plant. The weather monitoring system consists of the following: o

Temperature, barometric pressure, wind speed, wind direction, rainfall and relative humidity sensor

o

A heavy duty, tower/pole, hinged at ground level for instrument access with full height grounding kit

o

One PC based work stations along with a printer and weather monitoring system software at TER




o

One PC-based work station, with user level rights, at GTP CCR

o

One PC-based work station, with user level rights, at GGS Control Room

o

Sensor interface module

The sensors are installed on the weather tower/pole and/or in a weatherproof/ explosion proof enclosure at the base of the weather tower/pole. The system is powered from 230 V ± 1%, 50 Hz ± 5% AC supply from telecom UPS. 8.6

LOCAL AREA NETWORK

Office area PCs are connected through LAN. The LAN is based on Ethernet switches. Cat5e structured cable network support distribution of LAN services to the PCs, system computers etc. Dual RJ45 socket outlets for voice and data are provided for each work-station. The following buildings in GGS are connected by LAN: Living Quarters, Control Room, IER and Communications Room. 8.7

TELECOM SUPERVISORY SYSTEM

A Telecoms Supervisory System is provided with an equipment rack located in the GTP TER, with capacity for 80 digital inputs, cabled to a desk-mounted PC. The system can provide the status of any equipment connected to the system to an operator on the Ebla WAN, with appropriate password protection. The system can transmit a general major or a general minor alarm to the DCS to alert the operator and enable him to take necessary action.



9.0

PRODUCT SPECIFICATION



9.1



GAS & CONDENSATE SPECIFICATION

Dry Gas Outlet from Gas Dehydration Unit: 1.5 lb/MMSCF (31.5 ppm) Condensate Outlet from Condensate Coalescer: 200 ppmv 9.2

GAS

Gas Pressure Temperature Molecular Weight Mass Flow Rate Std. Vapour Volumetric Flow Rate

Unit bara C kg/kmol kg/h Sm3/h

Maximum 86.06 51.93 19.27 106191.00 130589.00

Minimum 68.10 7.83 18.75 46213.00 58376.00

Maximum 87.3 41.1 36.7

Minimum 85.9 7.86 7.86

Gas Composition Major Components H2S Water TEG Nitrogen Carbon dioxide Methane Ethane Propane i-Butane n-Butane i-Pentane n-Pentane n-Hexane Methanol 9.3

% mol 0.00133 0.00197 0.000107 1.42 3.27 87.43 3.95 1.92 0.39 0.69 0.28 0.24 0.00 0.00

CONDENSATE

Condensate Pressure Temperature Flow Rate

Unit bara C m3/h



CONDENSATE COMPOSITION Major Components H2S Water TEG Nitrogen Carbon dioxide Methane Ethane Propane i-Butane n-Butane i-Pentane n-Pentane n-Hexane Methanol

% mol 0.00 0.0862 0.00 0.19 2.2 27.43 4.07 4.62 1.70 3.91 2.92 2.99 0.00 0.94





10.0 PRE-REQUISITES FOR START-UP ACTIVITIES


10.1



PRE-REQUISITE – SAFETY

10.1.1 Introduction The prerequisite activities detailed below, shall be followed for restarting the Process units and utilities, after annual turnaround or long shut down. Also the Operator is encouraged to read the individual manufacturer’s Operation Manuals. The procedure presented here will only serve as a guideline. All standard Procedure for Plant Leak testing and purging of Hydrocarbon section of the plant shall be followed for safe and smooth start up of the plant. The PTW system of the Company shall be followed, as applicable for restart up the plant. 10.1.2 Safety All personnel should be familiar with the work permit issue system, location of safety equipment, portable fire extinguishers, safety shower and eye wash system. They should be familiar with proper usage of Personnel Protective Equipment (PPE). Similarly, the operator should be thorough with PTW system. The operator should be familiar with isolation of equipment and preparation of Blind Lists. The operator should know to do gas test and the minimum levels of oxygen required before giving permits for vessel/column entry. Operators should know about the various levels of harmful gases like SO2 and H2S, and about pyrophoric iron and the disposal of the pyrophoric iron wastes. Accumulation of pyrophoric iron wastes may catch fire when exposed to atmosphere. Hence it becomes essential to wet the Production Separator and all the vessels in the GGS during vessel maintenance so that fire hazards are avoided. Process equipment operating machinery, such as pumps and compressors, should be isolated, depressurized and purged before work is started. Electrical connections should be locked out at the MCC or switchgear. Electrical equipment should be tagged for proper identification and other personnel should know that it should not be switched ON when maintenance work is in progress for the particular electrical equipment. The loading systems, storage tanks and the diesel tankers should be ensured for proper grounding to avoid accumulation of static charges. 10.2

PRE-REQUISITE ACTIVITIES

Before the start-up of the plant, there are several pre-start-up checks and operations, which must be performed in order to prevent damage to the equipment and injury to operating personnel. The attention devoted to preliminary preparations for start-up contributes greatly to a safe and successful start–up. Various Pre-requisite activities before inert gas purging are as follows. 10.2.1 Vessels and Pipelines 

Ensure all vessels, opened up for maintenance during annual turnaround/shutdown are reinstated as per PTW procedures and ready for start up



Ensure all piping, dismantled for maintenance work, are reinstated



Ensure to fill required quantity of TEG in the Glycol Dehydration system




10.2.2 System Leak Testing and Purging Ensure the complete plant is leak tested with Plant air. Purging of all hydrocarbon system shall be done prior to introduction of Hydrocarbon. This purging applies to systems taken for maintenance. Follow Company’s Standard Leak Testing and Purging Procedures, as applicable. 10.2.3 HVAC in Control Room Ensure HVAC systems are ready .HVAC in control room shall be powered up and taken on line before switching on DCS system. 10.2.4 Diesel and Chemicals 

Ensue adequate quantities of diesel is unloaded and stored in the storage tank for start up of Emergency Diesel Generator



Ensure Chemicals required for injection are available

10.2.5 Checking of Functional Loop and Control Valves 

Ensure supply of instrument air and the Instrument air headers are lined up



Ensure DCS system is taken on line with UPS power and then supported with Power from EDG/GTG (once lined up with Fuel Gas from trunk Line)



Check Instrument control Valves for opening and closing



Check ESD functional check



Check F&G functional check at the field and Fire alarm Panel in control room

10.2.6 Charging of Lubricants for Rotating Equipment The following pumps and compressors must be filled with the applicable lubricants prior to starting up the equipment: o

Field Gas Compressor (304-K-001A/B)

o

Condensate Pumps (302-P-001A/B)

o

Early Operation Condensate Pumps (302-P-002A/B)

o

TEG Make-up Pump (305-P-002)

o

Glycol Circulation Pump (305-P-003A/B)

o

EDG

o

GTGs




10.2.7 L.P. Fuel Gas System Isolate gas header from Production separator and Gas header from Export gas header at the outlet of Gas Dehydration Column. Check the availability of Gas from Trunk Line and charge the Fuel Gas system as detailed in section 11 below.



11


START-UP OF UTILITIES AND OFF-SITE FACILITIES

NOTE: The following section is a guideline .Refer to the appropriate Operating Procedures if applicable.


11.1


Page 166 of 275

SEQUENCE OF START-UP

1.

Diesel system start-up

2.

Emergency power generator package

3.

Utility water system

4.

Potable water system

5.

Plant air system

6.

Instrument air system

7.

Nitrogen system

8.

Flare system

9.

Open drain system

10.

Closed drain system

11.

Fuel gas system

12.

Produced water system

13.

Gas turbine generator

14.

Methanol system

11.1

Operations

START-UP OF DIESEL SYSTEM

Start-up of diesel system will be done by importing diesel from outside. 1.

Ensure the diesel tank 322-T-001 is ready to receive diesel (If taken for maintenance)

2.

Check the functioning of instruments from DCS

3.

Check suction strainer for the pumps is cleaned and reinstated

Diesel Unloading Operation and Storage 1.

Ensure F&G system and all instruments such as 322-LI-3400 and High & Low level alarm tapings 322-LAHH-3402 and 322-LALL-3402 are ready

2.

Take sample of diesel from the truck and check whether the diesel meets specification

3.

Close 3” valve in the pipe line for diesel transfer pump suction 322-P-001

4.

Open pump suction valve of 322-P-002

5.

Park the truck carefully. Connect the truck to earthling provided at the truck unloading point

6.

Install unloading hose to the truck discharge line and connect it properly to unloading line of pump 322-P-002


7.



Slowly open truck valve and fill pump suction and casing (Notice for any leak at the joints and close truck valve if any leak is noticed)

8.

Check for any leak on the flanges and hoses

9.

Start 322-P-002 and check the performance of the pump

10.

Open discharge valve and note down the discharge pressure and check the flow to tank through the minimum-flow line

11.

Check all flange joints in tank as the level builds up

12.

Record the level rise in tank 322-T-001

13.

Stop 322-P-002 after completing unloading. Close truck unloading valve

14.

Close valve in suction of 322-P-002

15.

Disconnect the hose connection and earthling connection. Advise the truck operator to leave the point with utmost care

Diesel Transfer from Diesel Storage Tank to Distribution 1.

Close the Diesel Storage tank 322-T-0011 drain valve

2.

Close drain and vents in suction and discharge line for pumps 322-P-001A/S

3.

Open isolation valves for 322-PSV-0155 and 322-PSV-0156

4.

Open valves for Diesel Filter 322-F-001A/B. (Only one filter will be on line)

5.

Close drain valve and vent valves for 322-F-001A/B

6.

Close drain valve for Diesel Filter Coalescer (322-F-002A/B)

7.

Ensure to close valves at diesel supply header for Power Generation Packages 323-X-001A/B and Emergency Power Generator package 323-X-002

8.

Ensure the spill-back line from 322-P-001 to diesel storage tank is lined up

9.

Start 322-P-001A/S and check performance

10.

Check the 322-FO-3406 in the recycle line by watching the flow and discharge pressure of the pump

11.

On stabilization of pump operation, open valves to the diesel filter (322-F-001A/B) and watch 322-FI-3410 and the level in diesel tank 322-T-001

12.

All level indications in Tank 322-T-001 shall be monitored at DCS. Also note down the local level indication of tank whenever diesel is transferred to avoid spillage/overflow

Normal Operation 13.

Hazop Action No. 1200 Analyse Diesel quality prior to unloading from Diesel Truck. The diesel quality shall meet the specification including water content of less than 1000 ppm free




water. After the Diesel unloading into the Diesel tank 322-T-001receipt, proper settling time to be given so that water settles and water is drained out from the bottom drain of the tank. Again check diesel quality by taking a sample at the outlet of Diesel Filter Coalescer. The water content shall be less than 100 ppm. This sampling should be done during normal operation to ascertain the quality of diesel and proper functioning of Diesel Filter Coalescer. Hence proper monitoring of Diesel quality shall be ensured. Otherwise water in diesel more than specification will cause loss of ignition in EDG. 14.

Hazop Action No. 1203 The Diesel tank (322-T-001) is also provided with heating coils which can be used during winter when the temperature may reach below sub zero. Maintain proper temperature of diesel in the Diesel tank so that high water content does not lead to ice formation and thereby choking filter/pipeline. Ensure to drain water from Coalescer periodically to maintain diesel quality.

15.

Monitor and record diesel level in the tank and storage tank.

16.

Check the temperature of tanks and working condition of heaters

17.

Maintain record of diesel import into diesel storage tank

18.

Clean strainer in the suction line for pumps 322-P-002 and 322-P-001A/S

19.

Clean filters 322-F-001A/B if the pressure drop increases more than 0.5 bar

20.

Check the performance of pumps

21.

Check lubrication of pumps and refurbish, if required

22.

Keep the diesel transfer pump 322-P-001A/S as hot standby

23.

Monitor the water separated in 322-F-002A/B (whichever is in operation) at 322-LG-3420/3421.Drain the water as and when the water collection is observed

24.

Keep the diesel system on line for start-up of the power unit/emergency diesel generator

11.2

START-UP OF EMERGENCY POWER GENERATOR PACKAGE

1.

Check lubrication and coolant level

2.

Check the battery is healthy

3.

Ensure adequate level in diesel day-tank

4.

Line-up all instruments to local control panel and DCS

5.

Line-up diesel supply to EDG.

6.

Hazop Action No. 1195 Transfer diesel from Diesel Tank (322-T-001) to EDG by monitoring tank level when the level in the Day tank is low. Transfer diesel from Tank with 322-P-001A/S pump to day tank and closely watch the Day tank level. Malfunction of the Day tank float valve will lead to diesel overflow/spill and




possible fire hazards. Hence an operator has to manually check and ensure proper coordination while filling day tank of EDG. 7.

Ensure that incomer breakers and outgoing feeders of the Plant Emergency MCC are all open.

8.

Start manually the emergency diesel generator set from the local power panel or EDG control panel of the EDG set

9.

Black Start: The EDG set can be started if the starting batteries are in fully charged condition. The starting batteries of the EDG set are rated for 3-starts with an interval of 10 sec before lockout. Alternatively, the EDG can be started on compressed air with 3-starts with an interval of 10 seconds

10.

Energize the Emergency MCC by closing the DG incomer breaker on to the deadbus. The closing of the breaker is automatic if DC-UPS power is available and is carried out manually from the LV switchboard if the DC-UPS supply is not available

11.

The following critical loads on the emergency switchboard are to be started manually or from the PMS: a) Outgoing feeders to Main Emergency Lighting Distribution Board connected to emergency switchboard b) Outgoing feeder to Auxiliary Distribution Board of EDG c)

Outgoing feeder to substation HVAC panel

d) Outgoing feeder to control room HVAC panel e) Outgoing feeder to substation AC UPS f) 12.

Outgoing feeder to substation DC UPS

Additionally any or all of the following loads can be started, as required: a) Outgoing feeder to Emergency Auxiliary Distribution Board b) All outgoing feeders from 230 V AC UPS Distribution boards c)

All outgoing feeders from 110 V DC UPS Distribution boards

d) Outgoing feeder to Switchboard for GTG-A or B e) Outgoing feeder to other critical loads, if any 13.

Based on the process requirement the following process loads can be started from ICSS through the PMS as the case maybe: a) Outgoing feeder to Instrument Air Compressor-A/B/C (only one allowed to start) b) Outgoing feeder to HP & LP Methanol Injection Pump Electric Motor


c)



Outgoing feeder to nitrogen Generation Electric Heater Thyristor Control Panel

d) Outgoing feeder to Flare KO Drum Pump Electric Motors e) Outgoing feeder to Flare KO Drum Thyristor controlled Electric Heater f)

Outgoing feeder to other critical process loads (if any) connected to the Emergency Switchboard

Refer to Section 5 on Electrical Systems of this Manual for more details. 11.3 1.

START-UP OF UTILITY WATER SYSTEM Ensure Utility Water Tank 326-T-002 is cleaned and ready to receive water (If taken for maintenance)

2.

Line-up level instruments to DCS

3.

Ensure 326-P-003A/B utility water pump motors are solo run and coupled

4.

Ensure lubrication for the pumps

5.

Ensure power supply to 326-P-001A/S Borehole water pump

6.

Start 326-P-001A/S from local pushbutton and check the discharge pressure at 326-PG-4731

7.

Check the water flow at 326-FI-4726 to utility water tank

8.

Fill up the tank to 80%

9.

Set 326-LIC-4760 to Auto mode

10.

326-LIC-4760 gives command to 326-P-001 bore well pump to start at Low level and stop at High level of water in the utility water tank

11.

Ensure valves at utility water points are closed

12.

Ensure suction strainers for 326-P-003A/B utility water pumps are cleaned and reinstated

13.

Check the pump shaft is free

14.

Energise 326-P-003A

15.

Open the suction valve and keep the pump discharge valve closed

16.

Start the pump. Check performance

17.

Open pump discharge valve and control the discharge flow and pressure by controlling 326-PV-4723 in the recycle line to utility water tank

18.

Gradually open the utility header battery limit isolation valve and charge the header

19.

Keep 326-P-003B as standby pump


11.4



START-UP OF POTABLE WATER SYSTEM

1.

Ensure Potable Water Tank 326-T-003 is cleaned and ready to receive water

2.


3.

Ensure 326-P-004 water tanker unloading pump and 326-P-005A/B potable water pump motors are solo run and coupled

4.

Ensure lubrication for the pumps. Ensure power supply to 326-P-004A/S water tanker unloading pump

5.

Ensure suction strainer at water tanker unloading pump is cleaned and lined up

6.

Park the water tanker at designated place, nearer to the unloading pump

7.

Connect unloading hose from tanker to suction of the unloading pump 326-P-004A/S

8.

Start 326-P-004A/S from local pushbutton and check the discharge pressure at 326-PG-4775

9.

Check the water flow to potable water tank

10.

Fill up the tank to 80%

11.

Monitor the level at 326-LIA-4770

12.

Ensure valves at potable water points are closed

13.

Ensure suction strainers for 326-P-005A/B potable water distribution pumps are cleaned and reinstated

14.

Open the suction valve and keep the pump 326-P-005A discharge valve closed

15.


16.

Open pump discharge valve and control the discharge pressure at 4 barg

17.

Charge the potable water distribution header

18.

Header pressure is maintained by controlling 326-PV-4786 in the recycle line to potable water tank

19.

Keep326-P-005B as standby pump


11.5



START-UP OF PLANT AIR

General Ensure the pre-start and functional checking activities are successfully completed. When the system is started, the entire system should be checked at regular intervals for abnormal conditions. If an abnormal condition is observed, the system must be shutdown immediately and the cause investigated as given in Operation & Maintenance Manual of the package unit. All pertinent operational data and observations must be recorded. The following are the sequential steps for start-up of plant air system: Start-up of Plant Air System 1.

Ensure all instruments for the package and connected auxiliary systems are operable from Local control panel and DCS

2.

Ensure Compressor after cooler is lined up

3.

Line-up Plant air header and air receiver instruments:325-PI-4732 & 325-TI-4660

4.

Perform a pre-start check of the compressor

5.

Confirm that compressors are set for local control.

6.

Following the start-up procedure as per the vendor’s Installation, Operation & Maintenance Manual. Start Compressor No. 1 from local control panel.

7.

Confirm lube oil circulation and check operation of the lube oil separator

8.

Check the compressor for abnormal conditions (pressure, temperature, noise, etc.).

9.

After compressor reaches operating conditions, start recording data and observations on a ‘Log Sheet’

10.

Once satisfactory operation is obtained, keep the compressor on-line.

11.

Keep the Compressor 325-K-001B as standby

12.

Ensure all isolation valves in the field utility station are closed

13.

Once the compressor performs and meets the design criteria, slowly pressurize the Plant Air Receiver 325-V-001

14.

Close 2” vent valve and blind it. Open outlet valve of 325-V-001 for admitting Plant Air to the system network. Blow air through main header and each utility station header to confirm the Plant Air system is clean

15.

A service test is carried out at 8.5 barg to check the joint integrity of the system. Gradually pressurise the plant air distribution network




16.

Ensure plant air user valves are closed

17.

Open 325-XV-4665 at the outlet of 325-V-002 plant air receiver

18.

Line-up 325-PV-4660 manually and charge the plant air header. Check the flow at 325-FI-4663

19.

Set 325-PV-4660 at 8.5 barg and take the controller on AUTO mode

Refer Vendor Operating and Maintenance manual for further details. 11.6 1.

START-UP OF INSTRUMENT AIR Select Instrument Air (IA) Dryer to be on-line from Selector Switch. Line-up 325-X-002A; 325-X-002B goes to Standby Mode

2.

Line-up Plant Air to IA Dryer 325-X-002A

3.

Open the outlet valve of Instrument Air Dryer 325-X-002A to Instrument Air Receiver 325-V-002

4.

Ensure 325-XV-3275 in IA line to nitrogen is closed

5.

Start the Instrument Air Drier as per Vendor O&M Manual

6.

Check dew point and line-up On-Line Analyzer

7.

Controls from Local Panel for steady operation of the Compressor

8.

Ensure drain valve and bypass valve for Instrument Air Receiver 325-V-002 are closed

9.

Open 4” vent valve on Instrument Air Receiver 325-V-001 and close outlet valve

10.

Open inlet valve of 325-V-002

11.

Check instrument air pressure at 325-PI-4661

12.

Open outlet valve of 325-V-002 for admitting Instrument Air to the system network. Blow air through main header and each utility station header to confirm the Instrument Air system is clean and dry

13.

Check the dew point at the farthest point and ensure the dew point is –35C at 7.5 barg Hazop Action No: 550 Monitor the dewpoint analyzer (325-AI-4520 for Train-A and 325-AI-4570 for TrainB) for Train-A continuously and ensure the dewpoint is maintained at -35 0C at 7.5 barg. If the dewpoint increases to -340C at 7.5 barg, immediately high alarm 325AIH-4520 is activated. Always keep the standby Air Drier regenerated and kept ready so that it can be lined-up immediately if there is high dewpoint alarm. Excessive content of moisture in Instrument air may create acclerated corrosion in downstream users.


14.



Monitor compressor discharge pressure, dryer pressure drop, change over of dryers and dew point of dried air; log data on a daily basis

15.

Refer Vendor O&M Manual for further details

Normal Operation 

Ensure Plant Air Compressor is operating normally



Check pressure and flow rate of IA at DCS



Ensure the dew point –35C at 7.5 barg is maintained through On-Line Analyser



The following are set for the Auto-Start of the Running Compressor and Start/Stop of the Standby Compressor: Unload Compressor-B Unload Compressor-A Load Compressor-B Load Compressor-A Plant Shutdown

11.7

: 8.6 : 8.4 : 8.0 : 7.7 : 4.5

barg barg barg barg barg

START-UP OF NITROGEN SYSTEM

Pre-requisites for Start-up a)

Energise Local Control Panel

b)

Check for installation of all instruments in the system and control loops are checked (if taken for maintenance)

Start-up 1.

Start-up of nitrogen generator will be carried out as specified in the vendor manual

2.

Ensure the Instrument Air Receiver is under normal pressure (7-9 barg)

3.

Check Instrument Air dew point and confirm it is within specification limits (-35°C @7.5 barg)

4.

Ensure all instruments are hooked up to DCS. Ensure calibration of Oxygen Analyzer (324-AIT-4619) is completed, as described in the vendor manual

5.

Open 2” valve at the inlet of nitrogen .Package 324-X-001. Ensure closure of isolation valves at nitrogen utility stations

6.

Reset 325-XV-4725 and admit IA to nitrogen Membrane Unit 324-X-001

7.

Line-up nitrogen membrane unit 324-M-001, 324-M-002 and 324-M-003

8.

Line-up the inlet block valve and outlet ball valve of the membrane unit 324-M-001, 324-M-002 and 324-M-003

9.

Commission the Analyser 324-AIT-4619 and 324-PCV-4612




10.

Start membrane unit from Local Control Panel

11.

Line-up product block valve

12.

The product will automatically be vented through the product vent valve 324-XV-4620 & 324-HCV-003 until On-Specification N2 (98% purity) is generated

13.

Adjust purity control valve until the purity of product nitrogen is achieved

14.

When the O2 level in N2 product stream reaches 2%, the system will automatically switch product valves 324-XV-4616 and 324-HCV-002 to OPEN and product vent valve 324-XV-4620 & 324-HCV-003 to CLOSE

Refer Vendor O&M Manual for further details. 15.

Line up Nitrogen receiver

16.

Open block valve in the product outlet line from nitrogen generator and slowly admit nitrogen to Receiver 324-V-001.

17.

Pressurize the receiver and vent the nitrogen through drain from receiver

18.

Open outlet valve for the receiver and charge the nitrogen header

19.

Flush all nitrogen headers by opening respective isolation valves

20.

Stop flushing and check for any leak at flange and valves

21.

Change controls of nitrogen generator from local control panel to DCS

22.

Check the controls of nitrogen generator, both on Manual and Auto from PCS

23.

Monitor nitrogen purity

Normal Operation of Plant Air, Instrument Air and nitrogen Systems 

Line-up plant air header from 325-V-002instrument air receiver by opening 325-PV-4660



Set 325-PICA-4660 at 7 barg and take the controller on Auto



Line-up Master Pressure Controller 325-PT-4732 on Auto:



The instrument air header pressure is protected by following actions of Master Pressure Controller 325-PT-4732 of the systems:

1.

At 6 barg 325-PT-4732 commands closure of 325-XV-4665 plant air supply

2.

At 5 barg 325-PT-4732 commands closure of 325-XV-4725 instrument air supply to nitrogen package unit

3.

Monitor the operation of plant air compressor, instrument air system and nitrogen system; keep them running for start-up of the plant


11.8 1.



START-UP OF FLARE SYSTEM

Ensure lining up of all instruments in Flare Headers, Flare KO drum, Flare KO Drum Booster Pumps and KO Drum Pumps to DCS

2.

Ensure to line-up PSVs as shown in the P&IDs and equipment blowdown valves as given in P&IDs

3.

Purging of Flare Header shall be done with nitrogen .Ensure O 2 level is reduced to 2.5%

4.

Simulate and check the healthiness of 331-H-001 Flare KO Drum Heater

5.

Check the seal oil for the KO Drum Booster Pumps

6.

Check the lubricant for the Booster Pumps 331-P-001A/B

7.

331-X-001 Flare shall be lit as per vendor start-up procedure

8.

Ensure the flare is started with propane gas; keep the flare with propane supply until LP fuel gas system is established

9.

Ensure condensate collection in 331-V-001 Flare KO Drum

10. Start the heater if the level is above 50%; Start the heater; Line-up all instruments for the heater 11. Heater shall maintain 50C. The heater will start at 40C and stop at 60C 12. Keep ready KO Drum Booster Pump 331-P-001A (B as standby) on recycle by setting 331-FV-5160 on auto. 13. Line-up condensate from Booster Pump to suction of 331-P-002A 14. Check the operating pressure of Production Separator 15. Reset 331-XV-5129 and open the shutdown valve. 16. Start Flare KO Drum Pump 331-P-002A,if condensate level is more than 50% 17. Check the performance of the pump. Ensure condensate flows to production separator 18. Keep 331-P-002B as hot standby (keep open both suction and discharge valves open). 11.9 1.

START-UP OF OPEN DRAIN SYSTEM Ensure 332-V-001 Open Drain Sump is cleaned and kept empty (to collect any spill or storm water drain)

Start-up after electrical power supply is resumed 1.

Check the oil skimmer 332-Z-001 is positioned properly, after the shut down job




2.

Line-up all instruments in open drain sump and holding pond

3.

Keep the pumps 332-P-001A/S and 332-P-003A/S are energised

4.

Line-up 332-P-001A/S to holding pond and 332-P-002A/S to produced-water storage tank

5.

Ensure holding pond overflow line is clear

6.

Ensure 332-P-003A/S water disposal pump is in running condition.

11.10 START-UP OF CLOSED DRAIN SYSTEM The drains from the following sources are cleaned during shutdown and reinstated: o

Gas Flow Lines Manifold

o

Production Separator

o

Sample collection SC-301

o

Condensate Coalescer 302-F-002A

o

Sample Collection SC-314

o

Condensate Coalescer 302-F-002B

o

Condensate Solid Filters (302-F-001A/B)

o

Early Operation Condensate Pumps (302-P-002A/B)

o

Produced Water Storage Tanks 334-T-001

o

Fuel Gas KO Drum (321-V-001)

o

Field Gas Compressor Aftercooler (304-E-001A/B)

o

Flare KO Drum Pump (331-P002A/B)

o

TEG Regeneration System (305-X-001)

o

Gas Dehydration Column (305-C-001)

o

Field Gas Compressor Suction KO Drum (304-V-001A/B)

o

Field Gas Compressor Package (304-X-001A/B)

Ensure the vessel 333-V-001 is ready to receive drains from plant. Open valve at inlet to Closed Drain Vessel. Ensure valves in the Closed Drain Header from process equipment connected to 333-V-001 are closed. Open 4”valve in Flare Header from the closed drain vessel. Start-up after power availability 1.

All required electrical and instrumentation (including safeguarding) systems required for the Drain System is fully tested and commissioned

2.

Check and confirm lube oil level is at the correct level for the pumps

3.

Reset 333-XS-5321 for the heater


4.



Ensure power supply to Heater Control Panel and 333-P-001A/B

Normal Operation of 333-P-001A/B 1.

Set 333-LICA-5304 to AUTO mode. Line-up the pump discharge to 331-V-001 Flare KO Drum

2.

Open 333-P-001A/B Discharge Valves

3.

Open 333-P-001A/B discharge battery limit Valve

4.

Ensure the level of liquid is at Low Low level before draining from any process equipment

5.

Check level in 333-LIC-5304

6.

Drain out the liquid by pump 333-P-001A/B, if the liquid level is above Low Low

7.

Switch ON Heater E-333-H-001 and ensure the temperature of liquid is 50C before pumping out liquid

8.

Coordinate the draining of Vessel to avert High-High Level situations in Closed Drain system. The Drum levels are monitored during this activity both from Control Room and at field. Check in DCS

9.

Assess the quantity of liquid to be drained. If the inventory is more than liquid hold-up volume, then there is the possibility of overflowing or back-up of liquid in HC Drain Header

Normal Operation of Heater E-333-H-001 1.

Ensure collection of drained liquid (hydrocarbon) above Low Low level

2.

Ensure heater Healthy signal

3.

Start heater E-333-H-001 from DCS

4.

Set 333-TICA-5306 to AUTO mode Set Point = 50C 333-TICA-5306 works on: Temperature: L - Start Heater; H - Stop Heater

5.

Ensure liquid level in the Closed Drain Vessel before starting heater

6.

Switch OFF the heater manually from DCS when there is no liquid level in the Closed Drain Vessel

7.

Frequent start-up and stopping will damage the heater. Switch off the heater when not required

8.

Also switching on heater element without liquid will damage heater (Level shall be above Low-Low level alarm)




11.11 START-UP OF FUEL GAS SYSTEM The high pressure fuel gas is supplied to Power Generator Packages 323-X-001A/B. The supply sources of fuel gas are: o

Trunk Line: Start-up of GGS after planned shutdown

o

Production Separator: For start-up after complete shutdown/commissioning

o

Gas Export Header: After start-up and stabilization of GGS for normal operation of plant

1.

Ensure fuel gas system is purged with nitrogen (if the line is opened up with the resultant air ingress)

2.

Ensure Emergency Diesel Generator is supplying power to GGS (start-up requirement)

3.

Ensure flare is lined up

4.

Line-up PSVs for heater 321-H-001A/B , 321-H-002A/B and 321-V-001

5.

Ensure all drain valves and vent valves are closed

6.

Ensure supply of fuel gas from trunk line (large sink of gas)

7.

Ensure valves at the inlet of GTG are closed

8.

Line-up fuel gas through 3” line from trunk line to fuel gas system

9.

Drain the condensate from the pipe line to closed drain header

10. Gradually open 321-PV-3306 and admit fuel gas to KO Drum 321-V-001 11. Drain the condensate from the KO Drum 321-V-001 to Flare Header through the level control valve 321-LV-3311. Take 321-LV-3311 on Auto mode 12. Line-up fuel gas superheater 321-H-002A 13. Line-up 321-F-001A or B Fuel Gas Filter 14. Drain out the condensate from filter (first time) and close the drain valve 15. Energise heat tracing 16. Reset and start the heater 321-H-001A 17. Set 321-TIC-3352 at 15C and take it on AUTO 18. Ensure gas flow to superheater 321-H-002A 19. Start the heater 321-H-002A by switch 321-HS-3420 20. Set heater temperature at 321-TDIC-3323 at 15C and take it on Auto 21. Check the pressure drop across filter at 321-PDI-3319. 22. Fuel gas is ready to be admitted to GTG 23. Line-up fuel gas to field gas compressor (seal gas)




11.12 START-UP OF GAS TURBINE GENERATOR (GTG) The objective is to start GTG and energize the 11 kV Switchgear. Under normal conditions the sequence for the start-up of the Gas Turbine is given in the diagram given below. Normal healthy operation would follow the sequence on the left hand side of the diagram, though in the event of an abnormal stop, known as a ‘shutdown’ or ‘trip’, an extra stage is included called ‘turbine reset’ which requires the operator to acknowledge the condition which caused the engine to stop (as seen on the right hand side of the diagram). Fig. 13 – Start-up sequence of Gas Turbine




After initiation of any start, the turbine Operating state changes to “Active”. Within this “Active” state, there are a number of further sub-states:

o

Start Stage 1: The enclosure is purged and any other processes that don’t require the enclosure to be fully purged are carried out (e.g. testing of the emergency lubricating oil pump)

o

Start Stage 2: Processes that require a fully purged enclosure are carried out. (e.g. testing of fuel valves)

o

Acceleration to Spin Speed: The starter motor is engaged and the turbine is accelerated to spin speed

o

Spin Period: The engine is held at its nominal spin speed to allow for the exhaust and associated duct work to be purged of any gas fuel vapour from previous operation (Nominally 3000 RPM)

o

Pre-Ignition: Any processes that are required prior to ignition are carried out (e.g. priming of liquid fuel system)

o

Ignition: The igniters are energised and fuel is introduced. A failed ignition on gas fuel will cause the start sequence to revert back to the spin period in order to




allow ignition to be attempted several times. On liquid fuel the unit will trip in the event of a failed ignition attempt

o

Acceleration to Dwell Speed: The fuel and starter motor demand is increased to cause the engine to accelerate. During this phase the starter motor will be disengaged once the speed exceeds a required limit

o

Dwell Period: The engine is held (if required) at dwell speed to allow for warming of the engine (Nominally 8500 RPM)

o

Acceleration to Minimum Governed/Nominal Speed: The engine is accelerated to its minimum governed PT synchronous speed for a generator set (50Hz speed is 9525 rpm). Achieving this speed marks the end of the start sequence and the start of the running period

o

Loaded Operation: The engine is available for loading/unloading as required

o

Stop Holds: The engine is held for any processes that need to be carried out following the initiation of a normal stop sequence. (e.g. change to gas fuel for a short period on gas to purge liquid fuel nozzles)

o

Ramp to Minimum Governed Speed: The unit is automatically unloaded and lowered to minimum governed PT speed. On a generator set the generator breaker will be automatically opened once the load drops below a set minimum level (500 KW). A generator set will enter the ‘Shutdown’ state at this point.

The typical start sequence for the twin shaft generator unit is shown in the Fig 14. A twin shaft mechanical drive unit would be similar except that the PT speed would vary dependant on loading. A single shaft generator set would only have a single speed curve which is similar to the GG speed curve for the twin shaft up until the breaker is closed when it will then behave in the same manner as the PT speed of a twin shaft generator. Typical start times are given in Table. 1.




Fig. 14 – Start Sequence of Gas Turbine Unit

Table 1 – SGT Start Time

Control Modes Various engine speed/load control modes are available (dependant on configuration/ running condition).The various operating modes and output demand can be controlled either from the HMI or remotely (either via hard-wired connections or over a communications link). The output demand may be adjusted by using either raise/lower commands or by supplying an analogue demand signal.




The available modes are: Droop Control A proportional control mode where the difference between the speed demand and the actual speed will be dependant on the output power. Typically this will be based on a 4% difference equating to full load. Isochronous Control The output shaft speed is controlled to match the demand speed. This mode is available only when operating in island mode. Load Control Only used for generator drive units connected to a utility grid. Output power is controlled to match the demand. Temperature Control Only used for generator drive units connected to a utility grid, and without part load emissions control. Output power is controlled such that limiting temperature is controlled to a set demand Energization of 11 kV Switchgear at the Substation The dead bus closing of the bus-tie AB from GTG-A UCP and GTG-B UCP is to be carried out. The breaker close command from individual GCP is routed through a close permissive from the PMS which ensures that the 11 kV system is healthy. All incomer and outgoing breakers are in open condition and the switchboard is healthy with no faults. (In manual mode 11 kV Incomer and Bus Tie Breakers can be closed in Test position only). Operator to ensure that the 11 kV switchboard is a continuous bus with all bus coupler breakers closed before starting of the GTGs under plant start-up condition. Identify and start one of the GTGs (either GTG-A, or GTG-B). The feeders for the GTG-Auxiliaries shall be kept in ready to start condition, so that they can start when the signals are received from the GTG-UCP. The GTG Auxiliaries are: o

Starter Motor

o


o


o


o

Main Enclosure Vent. Fan 1 & 2

o


o


o

ABLOC Fan 1, 2 & 3

o

CACA Fan 1 & 2

o


o




o


o



All these feeders are located in the respective Gas Turbine Generator MCC Switchboard fed from the Emergency MCC. The first GTG is brought into circuit by dead bus closing of its 11 kV incomer breaker. The incomer circuit breaker ‘close’ command in the GCP is routed through a PMS close permissive contact which will ensure that the NER of the first GTG that is being brought into circuit is connected to the system, thus ensuring that the 11 kV System is earthed. On closing of the first GTG incomer breaker on to the HV switchboard, the 11 kV System gets energized and the 11 kV bus Voltage, kW and current feedback along with breaker status is available to the PMS and selectively to ICSS. Refer Section 5 of this manual and Vendor Operating Manual for more details. 11.13 START-UP OF PRODUCED WATER SYSTEM 1. Ensure Produced Water Storage Tank 334-T-001 is cleaned of sludge 2. Line-up all instruments for the produced water degassing drum and produced water storage 3. Ensure flare system is in operation 4. Ensure the tank and degassing drum are purged and under nitrogen pressure 5. Take the following control valves and keep them closed o 334-PV-5409 to Flare, 302-LV-1114 Production separator level control valve and 334-LV-5444 for degassing drum 6. Open Suction valve for 334-P-001 LP Produced water disposal pump 7. Line-up tank vent valve 3354-PCV-5409 and fuel gas line control valve to tank 3354-PCV-5408 8. Line-up blanket fuel gas to 334-T-001 by opening 334-PCV-5408 9. Control the tank pressure by operating 334-PV-5409 to TEG incinerator 10. Line-up Degassing drum 334-PCV-5449 to flare 11. Take all controllers on Auto 12. Keep the degassing drum and the produced water tank to receive produced water ready for operation 13. Keep the water disposal pump ready for normal operation 11.14 START-UP OF METHANOL SYSTEM 1.

Ensure Methanol Storage Tank 329-T-001 is cleaned and ready to receive water (if taken for maintenance)




2.

Line-up instruments to DCS

3.

Line-up blanketing (LP Fuel gas) gas to methanol storage tank by taking 329-PCV-4905 on line

4.

Control the tank pressure at 100mbarg by 329-PCV-4906 vent valve

5.

Set both control valves 329-PCV-4905 and329-PCV-4906 to Auto

6.

Ensure power supply to 329-P-001A/S methanol unloading pump

7.

Ensure suction strainer for methanol unloading pump is cleaned and lined up

8.

Park the methanol tanker at designated place close to the unloading pump

9.

Connect the earthing of truck and tote tank

10. Connect unloading hose from tanker to suction of the unloading pump 329-P-001A/S 11. Ensure 329-LT-4901 is taken on line (trips unloading/loading pump at Low-Low level and High-High level of the tank 12. Start 329-P-001A/s from local pushbutton and check the discharge pressure at 329-PG-4905 13. Check the methanol flow to methanol storage tank. Control the tank pressure Hazop Action No-300 The Methanol transfer to Tank 329-T-001 as well as tote tank is carried out using 329-P-001A/S. Ensure there is always continuous supply of LP fuel gas for the blanketing of Methanol Storage Tank 329-T-001. During methanol transfer ( Either to storage Tank 329-T-001 or to tote tank) if there is outage of LP fuel gas, stop the methanol transfer immediately. The transfer/unloading of methanol during LP fuel gas outage will lead to oxygen ingress into the tank and mix with oxygen to form a potentially explosive mixture. 14. Fill up the tank to 80% 15. Monitor the level at 329-LI-4900 16. Ensure valves at methanol loading point are closed 17. Loading of the tote tank is done by running 329-P-001A/S. Earth tote tank before filling with methanol. Start-up of Methanol Injection Package 18. Ensure adequate level of methanol in the supply tank 19. Line-up the suction from the Methanol Supply Tank to Methanol Injection Pump. 20. Line-up the suction strainer and flow meter at the discharge by opening isolation valves and close bypass valve. 21. Ensure priming of the pumps by draining water through the pump upstream drains.




22. Line-up the discharge relief valve and sight glass. 23. Start the injection pump. Monitor the discharge pressure, flow, current and vibration. 24. In case of any problems in the pump, stop it and then attend the problem. 25. Keep the pump stroke rate at maximum and observe the pump discharge flow rate. 26. Line-up the suction Calibration Tube and once level in calibration tube is stabilized, close the suction from tank. Monitor the level decrease in the calibration tube at fixed time intervals to find out the rate of pumping. Carry out this measurement for 25%, 50%, 75% and 100% of the stroke rates/lengths of the pump. 27. Once the calibration is over, keep the pump energised for plant start-up. The system is ready for methanol injection. 11.15 START-UP OF GLYCOL STORAGE AND TRANSFER SYSTEM 1.

Ensure Glycol Storage Tank 305-T-001 is cleaned and ready to receive Glycol

2.


3.

Ensure nitrogen purging of the tank and the system

4.

Line-up blanketing nitrogen gas to Glycol storage tank by taking 305-PCV-3049 on line

5.

Ensure the tank and pipelines are purged with nitrogen

6.

Ensure 305-V-001 drain vessel is ready to receive drains from dehydration and regeneration sections. Line-up drain vessel to flare

7.

Keep the drain pump 305-P-001 ready and line-up TEG regeneration system

8.

Control the tank pressure at 100 mbarg by 305-PCV-3048 vent valve

9.

Ensure suction strainer for make-up pump 305-P-002is cleaned and lined up

10. Park the glycol tanker at designated place – close to the unloading pump 11. Connect the earthing of truck and tote tank 12. Connect unloading hose from tanker to 305-T-001 glycol storage tank 13. Start the truck pump and fill the glycol storage tank 14. Stop filling once the tank level reaches 80%. Close tanker side valve and unloading valve 15. Make sure the requirement of glycol in dehydration system




16. Start 305-P-002 from local pushbutton and check the discharge pressure at 305-PG-4905 17. Run the make-up pump on recycle to glycol storage tank 18. Line-up 305-F-001. Open make-up pump discharge and transfer glycol to regeneration section. Stop the pump once desired quantity is transferred 19. The glycol from drain vessel is recovered by running 305-P-001 and the glycol is transferred to regeneration section.




12.0 START-UP OF PROCESS PLANT

NOTE: The following section is a guideline .Refer to the appropriate Operating procedure if available


12.1



START-UP SEQUENCE OF GGS

o

Ensure availability of power

o

Ensure all utilities are available at specified conditions as detailed under Section 11 above

o

Ensure safety systems are in place

o

Ensure DCS and ESD systems are taken on line

o

Line-up one Well head to start with (subsequent Wells are lined up after start-up of Production Separator)

o

Establish glycol circulation in dehydration column and regeneration section

o

Start Production Separator

o

Start Condensate System

o

Start Field Gas Compressor (LP system)

o

Start Dehydration System

o

Start Oily Water System

Plant Start-up Safety Meeting with all Parties Involved When all the utilities are started and available at the Process Plant, the plant is said to be ready for start-up. The operators should get involved in all stages of start up at the field and in control Room Activities. Regularly hold Pre-start-up meetings with various departments like Maintenance and Safety regarding the progress of work and safety involved in executing the work. Regularly conduct safety talks and model mock-drills for the Plant Operators. Test Safety and ESD Systems As part of the Pre-requisite activities for Plant Start-up, the Process Control System/ESD/Safety Shutdown System will be put on line. After this is completed, all level, pressure, temperature, flame failure and vibration switches should be activated to ensure their proper operation. Solenoid valves should be energised to check proper operation, especially for solenoid valves that activate emergency shutdown valve or depressurizing valves. Gas and fire detection devices should be made fully operational. The plant control panel and the local panels should be checked and made fully operational for start-up. All ESD input devices and switches should be loop-checked up to the control system to verify that the appropriate contacts are connected as shown in the PLC ladder logic function. o

Set all the Fail-Closed valves to the open position and all Fail-Opened valves to their closed position.




Activate each one of the unit blocks for ESD Level-1, ESD Level-2 & ESD Level-3

o

and check for the sequence of tripping. Refer Cause & Effect Diagram No: 250-EPR-CNE-05001 for all the ESD-1, 2 & 3. Verify that the ESD valves function as per the ESD logic. The ESD Level-1 will

o

open depressurizing valves; ESD Level-2 will enable depressurization and ESD-3 is used to only isolate or shutdown systems. Reset the system and verify all valves have returned to normal operating

o

positions. Similarly activate Fire & Gas Shutdown System and check whether the indicated

o

valves failed as indicated in the C&E diagram. 12.2

PURGING OF HYDROCARBON SYSTEM

Purging of Hydrocarbon handling systems; Production Separator, Field Gas Compressors, condensate system, Dehydration Units and pipeline will be done as per Company Procedure prior to introducing Hydrocarbon. 12.2.1 Facility Leak Test with Pressurization of Feed Gas 1.

After the nitrogen purging of the total GGS plant is completed, arrange for the leak test at 7 barg

2.

Keep the Flare system ready and commission all the utilities

3.

Ensure all vessel drains, level control valves, PSV bypass valves, vent and bleed valves, and instrument bleeds to atmosphere are closed

4.

Ensure all the PSVs are lined up to flare to take care of any pressure surges in the system

5.

Inform and readily keep Fire Trucks for any fire contingencies near the Well heads as well as near the GGS plant area

6.

Confirm the ESD valve 302-XV-1100 U/S of the Production Separator is kept closed and 302-XV-1157 (bypass of 302-XV-1100) and 302-HV-1158 are kept in open condition (to control the pressurization rate at downstream system)

7.

Force open 304-XV-1286 (bypass valve of 304-XV-1267) and line-up to Gas Dehydration Column 305-C-001

8.

Force open 302-XV-1102 (Condensate outlet of Production Separator) and line-up till the Gas Dehydration Column outlet ESD valve 305-XV-3004


12.3



START-UP OF PRODUCTION SEPARATOR

After purging and leak testing of the Production Separator, the Production Separator is started up as per the following sequence: 1.

Take 302-PV-1132 pressure control valve on manual and keep it closed

2.

Keep the level control valves at condensate line and produced water closed on Manual

3.

Ensure blowdown valve 302-XV-1109 is taken on line

4.

Ensure the shutdown valves 322-XV-1102, 302-XV-1101 and 304-XV-1200 are in closed condition

5.

Line-up all instruments to DCS

6.

Hazop Action No. 26 In case of extended shutdown period during winter conditions, the water in the Produced water lines from Production Separator should be completely drained. During Start-up, line-up heat tracing for all instruments and process lines before start-up. Ensure to switch “ON” heat-tracing lines for Produced water lines so as to avoid ice formation in water lines and reduce corrosion. While Start-up after Prolonged/Annual shutdown in winter, ensure to fully drain the Produced water lines so that freezing of the water lines are avoided. It is also recommended to drain out Produced water lines when the plant is taken on line after Annual shutdown. Failure of the heat tracing will lead to ice formation in the produced water lines and this will result to water carryover in condensate and causes accelerated corrosion in the pipeline.

7.

Ensure Well head is lined up to ESDV 302-XV-1100 at the inlet to Production separator

8.

Reset 302-XV-1157 at the inlet of Production separator

9.

Open 302-XV-1157 and pressurize the header up to 302-HV-1158

10. Gradually open 302-HV-1158 and pressurize the Production separator 11. Check the differential pressure at 302-PDIT-1107 is less than 2.5 barg 12. Open 302-XV-1100; 302-XV-1157 closes automatically 13. As the pressure is increased in the production separator, liquid starts condensing in the weir. Establish interface level and after the condensate level reaches the weir height, condensate overflows to the condensate side




14. Control the Production separator pressure at 87 barg with 302-PV-1137. Stabilise the separator pressure 15. Set the pressure controller 302-PIC-1137 to Auto. Continue flaring till stabilising the operation of separator 16. Commission the condensate level transmitter 302-LIC-1119 and the local level gauge 302-LG-1118; check both show the same level 17. After the condensate level 302-LIC-1119 reaches 30% level, this would require the following valves to be opened:

 Force open 302-XV-1102 and line-up condensate to the Early Operation Condensate Pumps (302-P-002A)

 Suction valve of 302-P-002A  Discharge valve of 302-P-002A  Pump safety valves 302-PSV-0135A should be car sealed in the open position. 18. At this time, the plant should have been purged free of air and leak tested to operating pressures. 19. Start Early Operation condensate pump 302-P-002A and line-up one of the Condensate Solid filters (302-F-001A) and Condensate Coalescer (302-F-002A). Take 305-LCV-1119 in Manual mode and keep it 20 % open 20. Ensure the condensate system is lined up as below 21. Ensure produced water system is also lined up to receive the produced water as detailed in below sections 22. Initial level of condensate can be lined up to Closed Drain header and later when the dry gas from Gas Dehydration column meets specification, it can be pumped back from Closed Drain Drum and Flare K.O Drum to Production Separator and avoid slug accumulation in the GTP trunk line Line-up of Gas to Fuel Gas System (Separator gas is lined up if gas from trunk line is not available) 

Ensure production separator operation is stabilised



Ensure Fuel Gas system is ready as detailed in Section 11.12 above



Open block valves at the inlet of 321-H-001A/B Fuel Gas heater



Open 302-XV-1207 and charge gas to Fuel Gas system

Refer Section 11.13 for lining up fuel gas.


12.4



START-UP OF THE CONDENSATE SYSTEM

After purging and leak testing of the Condensate System, it is started up as per the following sequence. 1.

After the condensate level reaches the weir height of the Production Separator, the condensate overflows to the condensate chamber in the production separator 302-V-001.

2.

Ensure all instruments are lined up to DCS and active.

3.

Line-up the suction valves of the Condensate Pumps 302-P-001A/B (LP Phase) or 302-P-002A/B (HP Phase).

4.

After the condensate reaches the Level Low height of 610 mm on the condensate side of the Production Separator, the ESD Valve 302-XV-1102 is forced open and the condensate flows to the suction side of the Condensate Pumps.

5.

Start the Condensate Pump 302-P-001A and commission the condensate system through the minimum-flow line 302-LV-1119.

6.

After the Condensate Pump performance is satisfactory, open the inlet block valves of the Condensate Solid Filters (302-F-001A) first and pressure up the A-filter. Commission the differential filter 302-PDI-1144. Line-up the isolation valves for the safety valve 302-PSV-105. In the same way, commission the Condensate Solid Filter (302-F-001B) and the safety valve 302-PSV-106.

7.

After start-up of the condensate solid filters, crack open the inlet valves of the Condensate Coalescer (302-F-002A) and slowly fill the Condensate Coalescer.

8.

Crack open the safety valve bypass of the safety valve 302-PSV-107 to release any nitrogen hold-up in the system.

9.

Water droplets start to coalesce in the mesh of the condensate Coalescer and develop a level in the boot of the Condensate Coalescer. Line-up the Interface Level Controller 302-LIC-1156A. As Level starts to appear as indicated in the Level Controller 302-LIC-1156A, open the level control valve 302-LCV-1156 manually and maintain the interface level.

10. In the similar way, Line-up the Condensate Coalescer (302-F-002B) as per steps 6, 7, 8 & 9. Start analysing the condensate samples; once it meets the specification it can be routed to the GTP trunk line. The condensate normally meets the specifications earlier than the dry gas from gas dehydration system; normal delay will not affect the Slug Catcher in receiving a bigger slug at GTP. If there is more delay in the Gas Dehydration and TEG Regeneration system, condensate can be drained to the Closed Drain Drum.




11. After the condensate meets the specification, adjust the Condensate Flow Controller 302-FIC-1182 flow such that the level in the Production Separator 302LIC-1119 is maintained at a normal level of 1510 mm. Then the condensate flow controller 302-FIC-1182 can be put in cascade with the Production Separator Level Controller 302-LIC-1119 (LP Mode operation). 12. In HP mode, level in the production separator is maintained by recycle line to production

separator

through

302-LV-1119

as

302-P-002A/B

are

positive

displacement pumps. 13. Check the condensate specification and it shall be lined up to trunk line. 14. Start corrosion inhibitor injection, after lining up condensate to Trunk line. 12.5

START-UP OF FIELD GAS COMPRESSOR (LP OPERATION)

12.5.1 Purging of Feed Gas Compressor Circuit As the Field gas Compressor loop for A and B are similar, the purging procedure for Compressor-A is given here; the same may be followed for Compressor-B also. 1.

Hook up nitrogen on the 2” utility connection on the bottom of FG Compressor Suction KO Drum-A (304-V-001A).

2.

Open the 2” valve to admit nitrogen into 302-V-001 and observe the pressure increase by observing 304-PI-1208.

3.

Force open 304-XV-1202. Take 304-LV-1210 in Manual mode and open fully to drain the condensate in 304-V-001A. Ensure that the condensate is drained fully; force close 304-XV-1202 and close 304-LV-1210 fully.

4.

Remove the blind for the 2” vent line for FG Compressor Suction KOD 304-V-001A and crack open the block valve for 5 minutes. After minutes, close the vent block valve and blind it.

5.

Hook up nitrogen in the 2” line (2”- 324-UN-1010-11J-V) on the suction piping of Feed Gas Compressor 304-K-001A.

6.

Open the casing drains of the compressor and keep it open for 15 minutes to drain any condensate in the casing of the FG Compressor-A. After 15 minutes, close the casing drains of Compressor-A.

7.

Slowly pressure up nitrogen up to ESD valve (304-XV-1219) at the discharge of the Compressor Aftercooler-A. Line-up to the Closed Drain header via line 2”-333-CD-1030-11K-V valve.


8.



Collect sample and analyse for oxygen content. If the oxygen content is less than 2.5 vol%, stop the purging operation.

12.5.2 Start-up The Start-up sequence takes care of all necessary controls and valve sequencing during the start-up. The Compressor is started with an open Antisurge valve. Once the motor is running at minimum speed, the Compressor can be loaded and the antisurge control will be switched from SEQUENCE to AUTO. 12.5.2.1 Start-up requisites 

Prior to initiating the Start sequence all trips have to be cleared and all start interlocks have to be fulfilled.



The casing and seal cavity shall be drained before every start-up.



Ensure the Compressor is in Standstill condition as indicated by 304-XA-1592

Check Availability of Seal Gas/Nitrogen as Seal Gas for Compressor 

Line-up seal gas (N2) to the compressor seals.



Ensure blowdown of compressor is reset and taken on line.

Energising Electrical Systems for Compressor (CRU) VSD system consists of 11 kV Incoming Power, VSD Switchboard, VSD with Converter transformer, Bypass Transformer, Remote Control Panel, Motor and Motor Local Control station. Refer to VSD Preliminary Start-up Manual of Electrical Motor supplier for start-up checks. Refer Vendor Motor Operating Instructions for start-up checks. Ensure termination of all power and control cables in each compartment of VSD system. Ensure the Incoming-side switchboards located in Substation are ready for energizing. Ensure Load-side equipment e.g. Switchboard, RCP, Bypass Transformer, Motor, LCS are ready for energizing. Testing of Variable Speed Drive System (VSD) for Initial Start-up VSD system includes the following equipment: VSD Switchboard Testing will be similar to HV Switchboard testing. Variable Speed Drive Testing shall be as per Vendor Preliminary Start-up Manual. 11/6 kV Step-down Bypass Transformer Testing will be similar to that of power transformers.




Compressor Motor Testing will be in accordance with vendor instructions. Remote Control Panel Testing will be similar to standard Control Panel. Energization of Electrical Equipment 11 kV, 6 kV Switchboards along with remote control panel located in CRU substation. 

Refer Vendor instruction manual for start-up checks.



Ensure that load side Equipment e.g. VSD, bypass transformer and motor are ready for energization.



Insert the circuit breaker in test position for initial checks and then in service position for energization.

Bypass Transformer 

Ensure the load side equipment e.g. motor is ready for energization.



Refer vendor’s O&M Manual for more details

Variable Speed Drive System for Compressor Variable Speed Drive in Test Mode With Test/Normal/DCS selector switch (SW1) located on VSD in ‘Test’ position, the VSD will Start/Stop via PBs located on VSD keypad. This shall be used for testing, commissioning & maintenance purposes only. Variable Speed Drive in Local (Normal) Mode With Test/Normal/DCS selector switch (SW1) located on VSD in ‘Normal’ position, the VSD will operate based on the position of a second switch Local/Off/DCS (SW2) located at the Motor Local Control Station. With ‘SW2’ in DCS, the VSD will operate via Start/Stop signal from Compressor PLC. Speed demand will be 4–20 mA signal input from Compressor PLC. With ‘SW2’ in Local position, the VSD will operate via Motor Local Control Station Start/Stop PBs. Speed Raise/Lower will be via PBs located on Motor Local Control Station. Variable Speed Drive in DCS Mode With Test/Normal/DCS selector switch (SW1) located on VSD in ‘DCS’ position, VSD will operate via Start/Stop signal from Compressor PLC. Speed demand will be 4–20 mA signal input from Compressor PLC. Bypass Mode (Fixed Speed)




For any fault on VSD or maintenance, Compressor Motor will operate in bypass mode (through bypass transformer) in fixed speed. For more detailed operation sequence of VSD in all the above modes, Auto/Manual Synchronous Transfer of VSD to Bypass and vice versa, please refer vendor VSD Operation philosophy Line-up of Instrumentation for Compressor 

Check compressor controls are integrated with DCS and functional checks of instruments are carried out - both from UCP and DCS



Ensure compressor Unit control panel and VSD compressor motor control panel are powered up.



Check the healthiness of control panel

Line-up Compressor - Condition monitoring Ensure line-up of condition monitoring system as per vendor’s instruction manual. Power up the system and check for healthiness of alarm, trip and process variables. Refer vendor’s instruction manual for details Line-up Compressor-Antisurge Control System Ensure Line-up of condition monitoring system as per vendor’s instruction manual. Power up the system and check for healthiness of alarm, trip and process variables Refer vendor’s instruction manual for details Blowdown System 

Line-up PSVs as shown in the P&IDs.



Line-up flare header from compressor.



Reset 304-XV-1364. Keep it closed.

Line-up of Seal Gas System 

Line-up of nitrogen as seal gas.



Ensure nitrogen bottles are connected to the seal gas manifold.



Line-up electrical tracing.



Line-up seal vent to flare through 304-PV-1464.



Ensure seal gas pressure is 27 barg.

Line-up of Secondary Seal & Separation gas 

Ensure N2 pressure is 5.0 barg



Ensure N2 as seal gas is lined up to the secondary seal and as separation seal gas

Line-up Field Gas Compressor After Cooler






Ensure lubrication for cooler fans; Start the fans and check performance.



Take 304-TIC-1315 on manual; Set the temperature at 60C.

Lube Oil System Start-up of Lube Oil System 1.

Lube oil is supplied to VSD (motor), gear box and compressor

2.

Ensure lube oil system is flushed (initial start-up)

3.

Check the oil level indication in 304- LG-1510 in the tank

4.

Ensure lube Oil Filters are cleaned; line up one filter with the other as standby.

5.

Ensure trial run of the oil system is completed and ready for continuous operation

6.

Switch on Oil heater 304-H-001A

7.

Open Oil inlet valves to bearings and other points. Open all valves in the return line to tank

8.

Open the valve in the bypass line of Oil pressure control valve 304-PV-1510

9.

Check the oil temperature in the oil tank (to keep the desired viscosity of oil)

10. Start the Auxiliary Lube oil pump 304-P-002A 11. Ensure the oil temperature reaches 35C 12. Gradually close bypass valve for 304-PCV-1510 13. Check the pressure drop across the filter 14. Remove the entrapped air in the oil cooler by opening vent valve. Close the vent valve on noticing ‘No air bubbles’ in the oil being drained through vent valve 15. Start the Oil cooler fans and take them on Auto mode 16. Similarly vent oil in the filter to ensure that air in the oil system is completely removed 17. Check the oil supply pressure and the return oil flow in the sight glass 18. Check the oil temperature in supply lines to bearings 19. Check the Auto start of standby auxiliary pump 20. Now lube oil system is established Refer the section on operating instruction manual of the vendor for more details. Start-up of Compressor 1.

Ensure pre-requisite for Compressor start-up is completed

2.

Ensure DCS, anti-surge control system, temperature monitoring system and condition monitoring system are lined up as per Vendor’s instruction manual


3.



Check the operation of anti-surge valve 304-FV-1212 and flare vent valve 304-PV-1294 from local control panel

4.

Ensure healthiness of seal gas system and lube oil system

5.

Ensure trial run of VSD is completed and coupled to compressor (initial start-up)

6.

Ensure healthiness of motor local control station, remote control panel, ESD panel, Compressor PLC system and VSD switchgear

7.

Power up VSD and check the readiness of motor (Check the interlock for start-up is active). Refer the section on operating instruction manual of vendor

Charging of Gas to Compressor 1.

Ensure the system is under nitrogen pressure

2.

Ensure gas pressure at Production Separator is 27 barg or greater.

3.

Line-up KO Drum 304-V-001A. Take 304-LIC-1210 on Auto

4.

Reset 304-XV-1219 at compressor discharge and keep it closed

5.

Reset 304-XV-1200 and 304-XV-1201 at KO drum inlet.

6.

Select the Compressor start-up in ‘Sequence’ start-up mode

7.

Line-up antisurge control system. Open 304-FCV-1212

8.

Open 304-XV-1201 and admit gas to compressor.

9.

Ensure the pressure drop is less than 2 barg. 304-PDT-1206 automatically opens 304-XV-1200 and suction of the compressor is pressurized

10. Drain the condensate from compressor casing, pipe lines and KO drum Starting of Compressor 1.

Check the compressor suction pressure is about 27 barg as indicated by 304-PI-1226.

2.

Make sure that start-up interlocks have been released by the control system of the compressor unit.

3.

Ensure the Start-up permissive from DCS is clear.

4.

Check the indicators in the compressor control panel.

5.

Check for any alarms and healthiness of start-up system. In case of malfunction or start-up conditions are not achieved, take corrective action and ensure ‘Ready for Start’ is indicated in the panel. “Ready for start-up” permissive appears as indicated by 304-XA-1693.

6.

Check the speed control is at minimum.


7.



Ensure compressor discharge cooler fans are running and 304-TIC-1215 on Auto mode.

8.

Select compressor suction pressure 304-PI-1226 as control set pressure.

9.

Set the compressor discharge at 87 barg and take it on Auto control.

10. Now the Compressor “Start-up Auxiliaries complete/Pressurized” is completed and “Ready to Start Motor” indication appears. 11. Inform electrical substation for Starting of the Compressor Motor. Following is the sequence for start of motor in VSD Mode 1.

Close the VSD input breaker using T/N/C switch.

2.

Keep the selector switch in ‘Normal’ mode on VSD system.

3.

Keep the selector switch in Local mode on Local control station.

4.

See the VSD ready indication on Unit Control Panel.

5.

Press the VSD Start pushbutton on the Unit control Panel.

6.

See motor running on VSD indication on Local control station as indicated by 304-MXI-1634.

7.

Check the speed, discharge pressure, lubrication, seal gas pressure and secondary seal gas pressure.

8.

Check compressor vibration and temperatures at the bearings.

9.

Check the compressor discharge pressure and performance of the compressor.

10. Check the gas temperature at the discharge cooler outlet of first stage. 11. Monitor the gas cooler outlet temperature and control at 60C by taking 304-TIC-1215 in Auto Mode. 12. Raise the compressor speed by selecting ‘speed increase’. 13. Raise the speed of the compressor to 1200 rpm and check the compressor discharge pressure at 304-PI-1232. 14. Gradually raise the compressor discharge pressure to 87 barg, with careful monitoring of compressor for vibration, temperature at the bearings, discharge pressures and the gas outlet temperature at the outlet of gas coolers. 15. Set the discharge pressure at 87 barg and take the compressor operation on Auto mode. 16. Check the performance of the compressor for vibration, discharge pressure, bearing temperature, gas flow etc as detailed in the compressor vendor’s instruction manual.




17. Now the speed of the compressor is controlled by the suction pressure 304-PI-1221 of the compressor. 18. Monitor liquid level 304-LIC-1210 in suction KO Drum 19. Take electrical tracing heater on Auto mode. 20. Monitor the condition of the compressor and its auxiliaries. 21. Check Dehydration column operating pressure. 22. Open 304-XV-1219 at the compressor discharge and allow the gas to Dehydration Column. 23. Control 305-C-001A Dehydration Column pressure by taking 305-PV-3024 on Manual. Set 305-PIC-3024 to Auto mode after stable operation of dehydration column. 24. Take 304-PIC-1294 on Auto mode. 25. Monitor the seal gas flow and pressure. Maintain the seal gas vent to flare through 304-PV-1464 by maintaining 1 barg above flare header pressure. 26. Once the compressor performance is established, change the selector switch in VSD to DCS position (or change the selector switch in motor LCS to DCS position). 27. Now the compressor control shall be taken over by compressor PLC in control room. 28. Monitor the performance of the compressor from compressor PLC in control room. 29. Once the compressor is loaded, the anti-surge and performance controllers will be switched from SEQUENCE to AUTO. Line-up of Seal Gas from Process Gas 1.

Isolate nitrogen supply. Commission the seal gas supply from 1’ seal gas take-off from the Compressor discharge side. (In case of settle-out pressure (46.4 barg), the seal gas supply is supplied from the HP Fuel Gas tapped from the D/S of Fuel Gas Heater (321-E-001A/B) to ensure dry heated gas supplied to Dry Gas Seals.

2.

Ensure fuel gas system is lined up.

3.

Open 304-XV-1295 and line-up fuel gas to compressor.

4.

Ensure to drain any condensate collected in the KO Pot.

Refer the section operating instruction of Vendor Operating Manual for more information. 12.6

START-UP OF GAS DEHYDRATION SYSTEM

The glycol regeneration and circulation systems should be started prior to passing process gas through the glycol column. Once the glycol is present on the chimney tray




inside the column, the gas flow and glycol flow may be started or stopped independently with no harm to the system. With the column charged with glycol, the pump may be stopped for some minutes without seriously affecting the drying of the gas, which will be effective to a decreasing extent as the glycol standing on the structured packing becomes saturated with water. Glycol system shall be started prior to lining up gas to Dehydration column. Pre-Start-up Requisites 

Inspect all glycol and gas lines; ensure they are all tight. Hot glycol can leak through connections which might be considered tight when cold. Hence it is necessary to re-tighten some connections once the hot glycol is being circulated under pressure.



Inspect all instruments and adjust where necessary.



Check the levels inside the vessels.



Check the pressures of the Gas Dehydration Column 305-C-001 to be atleast upto 7 barg.



Check the pressures of the Flash Drum 305-V-002 to be 3.8 barg.



Check the pressure of the Fuel gas KO drum (305-V-004) to be 5 barg.



Check the availability to operate of all electric motors (Pumps, Blowers and Air Fans)



Hazop Action Action No. 758 Drain the liquid accumulated in the Vent Gas KO Drum (305-V-003) by observing the Level gauge 305-LG-3135. If it is prolonged shutdown drain KOD and also ensure to switch on the heat tracing on the pipelines to maintain the fluidity in the line. The Field operators should ensure regular observance of the Vent Gas KOD liquid level and drain the liquid at frequent intervals. If the level builds up, then entrainment to Blowers will cause potential damage to the Blowers.



Drain the Blowers casing of the selected Vent Gas blowers 305-K-002A/B or C/D by opening eight ball valves on each Blower casing assuring that all possible condensate is drained off before burner ignition and then close the drain valves.




12.6.1 Initial Start-up 12.6.1.1 Pressurizing of 305-C-001 with Gas Feed 1.

During the early phase (HP Phase) as the pressure is on the higher side, the Field Gas Compressor section is kept in bypass condition. Ensure the following valves are kept in closed condition. 

The block valves upstream of ESD valves 304-XV-1200 and 304-XV-1201 for Field Gas Compressor-A is kept in closed condition. Install blind in the D/S flange of second block valve.



The block valves upstream of ESD valves 304-XV-1300 and 304-XV-1301 for Field Gas Compressor-B are kept in closed condition. Install blind in the D/S flange of second block valve.

2.

Open the 2 Nos 6” Ball valves on the Feed Gas line from the Production Separator to the Gas Dehydration Column (305-C-001).

3.

Arrange to force open valve 304-XV-1286.

4.

Slowly admit Feed Gas to the Dehydration Column (305-C-001) and pressurize 305-C-001 up to 7 barg.

5.

Take 305-PIC-3024 on Auto mode with a set point of 7 barg to HP flare. After this, take 305-PIC-3009 on Manual mode and set 305-PV-3009A and 305-PV-3009B MV to zero. Closely watch the pressure in the column as indicated by 305-PIC-3024 and 305-PIC-3009 maintaining 7 barg. During the first start-up and every time the Gas Dehydration Column is depressurized, restarting of pressurization is done manually for checking of leak

12.6.1.2 Glycol Filling in TEG Reboiler and TEG Surge Drum 1.

Charge the TEG Reboiler (305-H-001) and TEG Surge Drum (305-V-005) through the 2” glycol filling connection line 2”-305-GY-1818-11J-E.

2.

Hazop Action No. 757 In cold weather conditions TEG (Tri-Ethylene Glycol) is viscous and has to be warmed up to facilitate pouring. 

During winter months, when air temperature might fall to -15°C (min. ambient temperature) ascertain that Gas Dehydration Column bottom, the wet condensate outlet line and the chimney tray portion of the column are heated by electrical tracing.






Switch on the electric tracing system on the level instruments installed on the Flash Drum 305-V-002, on the TEG Reboiler 305-H-001, TEG Surge Drum 305-V-005, stand-by pump and in general where electrical tracing is given.



Increased viscosity of glycol in Surge vessel may affect the pumping and potentially damage the glycol circulation pumps at cold operating conditions. As the glycol lines are heat traced and insulated to retain the hot condition, it becomes necessary to restart the electrical heat tracing and then start the Glycol Pumps especially after prolonged shutdown and cold winter conditions.

3.

Start filling to about two-thirds level in the TEG Surge Drum (305-V-005) as indicated in level gauge (305-LG-3114), leaving one third empty space for liquid to expand on heating.

4.

The TEG Reboiler has an internal overflow weir through which the glycol will flow into the TEG Surge drum, through the stripping column.

5.

Continue to fill the TEG Reboiler, until a liquid level appears in the surge drum. Stop filling when the surge drum level reading on the level gauge 305-LG-3114 is 500 mm (from lower part of Surge). Reset Low-Low shutdown level 305-LALL-3116.

12.6.1.3 Glycol Filling in Glycol Flash drum & Glycol Filters 1.

Make sure that that the ball valve on the outlet line from the Pumps 305-P-003A/B (going to 305-E-004) is kept closed.

2.

Line-up the Ballvalve/Globe valve on the start-up lines 2”-305-GY-1023-11A-P and 2”-305-GY-1015-11A-P.

3.

Open the isolation valves on the start-up line 2”-305-GY-1023-11A-P on the Glycol Circulation Pumps (305-P-003A/B) discharge line which routes the glycol to the Flash drum (305-V-002).

4.

Start one glycol pump 305-P-003A. While the pump is running visually check the pipelines. If any leaks are present tighten the bolts and arrest the leak.

5.

Continuously monitor the level inside the Surge drum and the Flash drum. The level in the Surge drum (305-V-005) should be topped up before reaching the minimum level of 300 mm.

6.

When the level in the Flash drum (305-V-002) reaches the normal level of 750 mm or is higher than 370 mm (LLLL), stop the Glycol Pump. Top up the Surge drum level if required.


7.



Pressurize the Flash drum with the blanketing gas upto 3.8 barg by opening the manual valves around 305-PV-3201. Manual valves around 305-PV-3211 must also be opened.

8.

Once the Flash drum is pressurized to 3.8 barg, reset the LLLL and then open the shutdown valve 305-XV-3213 on the Glycol outlet line.

9.

Open the manual valves upstream of the TEG Catridge Filters (305-F-003A/B). Slowly open vent valve to completely fill the filter and vent. Fill and vent both the filters so that one will be on service and the other active stand-by.

10.

Slowly line up the TEG Carbon Filter (305-F-002) as explained above for the Rich TEG Catridge Filters.

11.

Line up the Hot Lean/Rich Glycol heat exchanger (305-E-002) upto the TEG Still column (305-C-002) and check for any leaks. Arrest leaks if any.

12.

Line-up 305-LV-3210 and glycol can be kept under circulation in order to establish the levels inside both the vessels. Top the surge drum if required.

12.6.1.4 Glycol Circulation/Pressurization of Gas Dehydration System 1.

Close the manual valves on the start-up line 2”-305-GY-1023-11A-P previously opened to fill the Flash drum (305-V-002). Open the Ball valve and line up to 305-E-004.

2.

Line-up one of the Glycol Circulation Pumps 305-P-003A/B. Open suction and discharge valves of the pump 305-P-003A which is selected for use. Line-up block valves on 305-E-001, 305-E-002 and 305-E-004 exchangers and Gas Dehydration Column (305-C-001).

3.

Select the Local mode by pressing 305-MHSM-3121 on the Local panel and start the pump 305-P-003A by pressing start pushbutton 305-MHSH-3121. Check for the Running indication 305-MIXI-3121 of 305-P-003A in the DCS Panel.

4.

Lean Glycol starts flowing to the Dehydration column. Check the Glycol pressure and the flow as indicated by 305-PI-3129 and 305-FI-3113.

5.

The Glycol lines get filled up before a glycol level appears in the chimney tray of Gas Dehydration Column at 305-LG-3018 and in DCS by 305-LIC-3017. Observe the pump (305-P-003A) for lubrication, discharge flow and discharge pressure.

6.

TEG entering the Gas Dehydration absorber passes through the structured packing and then it is collected at the bottom of chimney tray. When the glycol level




appears on the Level Gauge 305-LG-3018, stop the glycol circulation pump 305-P-003A. 7.

At this point Column is ready to be pressurized by admitting some gas up to the pressure of 85.2 barg. Do not start the gas flow at this stage. Only pressurize the Dehydration Column (305-C-001). Keep 305-PIC-3024 on auto with set point of 85.2 barg. Take 305-PIC-3009 on manual mode with 305-PV-3009A and B kept in fully closed condition.

8.

When the level inside the Chimney tray is higher than LLLL of 4320 mm, reset the Low-Low Level trip and the shutdown valve 305-XV-3002 can be opened allowing the glycol to be discharged from the Dehydration Column.

9.

Observe level build-up in the chimney tray of 305-C-001. Once the normal liquid level of 4780 mm level reaches on the chimney tray, put level controller 305-LIC-3017 into Auto with 305-LV-3017 to return TEG back to the Glycol Regeneration Package.

10. Shut-off the Glycol Pumps 305-P-003A and top up the TEG Surge Drum if level is low. Once the Glycol Pump is stopped, the glycol level control valve 305-LV-3017 closes. 11. Ensure 305-PCV-3211 to flare from Flash drum is set 4 barg and taken on Auto. 12. Line-up the manual block valves in Blanketing Gas Line to Flash Drum (305-V-002) and pressurize to 3.8 barg by setting 305-PCV-3201 at 3.8 barg. 13. Put the level controller 305-LIC-3017 on Auto and return the rich TEG to the TEG Reflux Condenser (305-E-003). Rich TEG will then flow down to the Flash Drum through the Exchanger (305-E-002). 12.6.1.5 Heating of Glycol in the TEG Reboiler 1.

The gas burner assembly for the TEG Reboiler can be started either from DCS or from Local panel. 

Pilot ignition will be carried out with Ignition Electrode through Ignition HighEnergy Transformer.



Temperature Control will be carried out through an air/gas ratio control valve actuated by Temperature controller 305-TIC-3109.



The burner can be lighted only after the complete filling of the Reboiler with glycol. Attempt to light on the burner without Glycol will damage the firetube.






The logic sequence describes the starting and fully automatic controlling with ESD for the forced draft burner. Ignition sequence can start only if none of the following shut-off causes occurs:



ESD-1, ESD-2 & ESD-3 Emergency shutdown



305-LAHH-3016 - High-High Glycol level on 305-C-001



305-LALL-3110 – Low-Low Glycol level in Reboiler 305-H-001



305-LALL-3116 - Low-Low Glycol level in Surge Drum 305-V-005



305-PAHH-3173 – Low-Low Gas pressure to Burner



305-TAHH-3107 – High-High Glycol temperature in Reboiler 305-H-001



305-BSL-3163 - Lack of Pilot Flame



305-PAHH-3128 – High-High discharge pressure of glycol circulation pumps (305-P-003A/B)



305-FALL-3147 – Low-Low Air pressure to Burner.



305-LAHH-3208 – High High condensate level in Glycol Flash Drum (305-V-002)



305-LAHH-3209 – High- High Rich TEG Level in Glycol Flash Drum (305-V-002)



Flame Scanner Fault.

Sequence for Burner Ignition Burner start-up sequence will start only when the following permissives are met: 

The flame detector tag 305-BE/BSL-3163 does not signal flame presence.



The limit switch 305-XZSL-3169 does signal that the Shutdown Valve 305-XV-3169 in the pilot fuel gas line is closed.



The limit switch 305-XZSL-3168 does signal that the Shutdown Valve 305-XV-3168 in the pilot fuel gas line is closed.



The limit switch 305-XZSH-3165 does signal that the Shutdown Valve 305-XV-3165 in the pilot fuel gas vent line is open.



The limit switch 305-XZSL-3167 does signal that the Shutdown Valve 305-XV-3167 in the main burner fuel gas line is closed.



The limit switch 305-XZSH-3166 does signal that the Shutdown Valve 305-XV-3166 in the main burner fuel gas line is closed.



The limit switch 305-XZSH-3170 does signal that the Shutdown Valve 305-XV-3170 in the main fuel gas line is open.






The limit switch 305-XZSL-3171 does signal that the Shutdown Valve 305-XV-3171 in the stripping gas line is closed.

Burner Ignition Sequence Burner can be started either from the DCS by (305-HS-3151A) or from Local panel by (305-HS-3151B). During start-up cycle if any shutdown signal is received, then the start-up sequence will be aborted. 1.

Press ‘Start Burner’ pushbutton and the following operation are done in automatic sequence:  Start the selected Burner Air Fan (305-K-001A/B)  Start the Burner Air Fan 305-K-001A by pressing the Start pushbutton 305-MHSM-3182.  The Burner Gas Blower 305-K-001A running indication is displayed on DCS panel by 305-MXI-3182. 

Start the selected Vent gas Blowers (305-K-002A/B) by the following actions and line-up to the TEG Incinerator.  Select Local mode by pressing the Local/Remote Selector switch 305-MHS-3131 and 305-MHS-3132 in the Local Panel.  Start the Vent Gas Blower 305-K-002A by pressing the Start pushbutton 305-MHS-3131B in the local panel.  The Vent Gas Blower 305-K-002A running indication is displayed on DCS panel by 305-MXI-3131.  Similarly start the other Blower 305-K-002B and ensure the two Vent gas Blowers are running in series



Force “Open” Fuel Gas Control Valve 305-TV-3109.



When both the blowers ‘Running’ signal appears for 305-K-001A or B, 305-K-002A/B or (C/D) and the valve 305-TV-3109 is open, and air flow is established by 305-FALL-3147 (reset).



Start “Purging” gives signal with ‘Purge On’ (305-XL-3158) indication on local panel 305-PKG-LCP-01 for 60 seconds.



After 60 seconds of purging, force open control valve 305-TV-3109 to minimum position, switch off the indication ‘Purge On’ on local panel beside the burner.






After the control valve 305-TV-3109 is set to minimum (confirmed by limit switch 305-TZSL-3109, open shutdown valves 305-XV-3168 & 305-XV-3169 and close 305-XV-3165 on pilot gas line.



Power is given to the Spark Ignitor for 30 seconds 305-EE-3164.



When the limit switches 305-XZSH-3168, 305-XZSH-3169 and 305-XZSL-3165 give signal that the valves have reached the desired position, the spark ignitor 3005-EE-3164 ignites for 30 seconds.



If the flame scanner detects the flame within 30 seconds ‘Pilot On’ lamp (305-XL-3157) glows on the local panel.



If the flame is not detected within 30 seconds, ‘Flame Scanner Fault’ indication glows indicated by 305-UA-3154 and once again the purging procedure starts.



Check the pressure of the pilot gas to 0.3 barg and adjust 305-PCV-3176 if required.



Check the flame quality adjust the gas flow and the air flow using dedicated valves on the pilot gas Assembly.

12.6.1.6 Lighting of TEG Reboiler Main Burner 1.

Once the Pilot flame is detected, following operations are done in automatic. 

“Pilot On” lamp (305-XL-3157) lights on in local panel.



After the Pilot flame is stabilized, open shutdown valves 305-XV-3167 and 305-XV-3166 and close 305-XV-3170 on the main gas burner line.



When the limit switches 305-XZSH-3167, 305-XZSH-3166 and 305-XZSL-3170 give signal that the valves have reached the desired position, start 30 seconds of main flame stabilization.



When the Main flame stabilization time is over and the burner start-up sequence is completed, ‘Burner On’ indication appears on the local panel (305-XL-3156B) and on DCS (305-BAH-3156A).



At this point the automatic sequence should remove the force controls on 305-TIC-3109 but some adjustments on the main burner shall be required. Therefore it shall be convenient to keep the control in manual mode since the main flame is properly adjusted.

2.

Put 305-TIC-3109 on temperature control with 305-TV-3109 on Auto.


3.



Set maximum temperature gradient of 60C/hr and set point for 305-TIC-3109 at 204ºC.

12.6.1.7 Circulation of Hot Glycol in the System 1.

After performing the Burner start-up, progressively increase the set point for 305-TIC-3109 up to 204°C. (If the heating process is slow, then the inventory in reboiler is heated, raise the temperature to 204°C and circulate through the system). 

Open the valves on the start-up line 2”-305-GY-1015-11A-P and start the glycol circulation starting a pump and allowing the warm up of the Reboiler and surge drum.



When the temperature inside the Surge drum reaches approximately 90°C, open the valves on the start-up line 2”-305-GY-1023-11A-P and close the line 2”-305-GY-1015-11A-P allowing to warm-up the Flash drum and the glycol filters.



When the temperature inside the Reboiler reaches 150 0C, start the Glycol circulation to the Gas Dehydration Column 305-C-001.



Open the shutdown valve 305-XV-3003, then close the valves on the recirculation line previously opened (Globe valve first then the Ball valve). The pressure on the pump outlet will increase upto the required pressure to allow the glycol enter the column and then open the shutdown valve on the outlet line 305-XV-3002



The level inside the Chimney tray shall be controlled by the valve 305-LV-3017.

2. The glycol circulation is complete and the glycol temperatures should reach the design values. Do not exceed 204C in the reboiler and increase the temperature at a rate of 60C/hr. During this operation, care should be taken for the free expansion of equipment and piping. Sliding supports shall be free to slide and no stress or constraint shall develop on equipment saddles, nozzles or pipes supports. 3. During this heating operation, one shall also check for leaks and tight wherever necessary (the low surface tension of glycol at high temperatures encourages leakage). Check the liquid level in particular inside the Surge drum because of thermal expansion.




12.6.1.8 Putting Stripping Gas into Service Quantity of stripping gas depends on the operating conditions of TEG Regeneration system. Five operating cases have been evaluated and stripping gas quantity is given on the PFD. The flow rate quantity can be measured by the local flow indicator 305-FIT-3177/DCS indicator (305-FI-3177) and adjusted by means of the globe valve installed on the stripping gas line. NOTE: Stripping gas flow can be started manually by opening the shut down valve 305-XV-3171 on the stripping gas line and is allowed only if the burner is ON. Once the burner is switched off, 305-XV-3171 will close automatically. After burner restart, the valve has to be re-opened manually by first resetting in the Local panel and open by operating the switch 305-XHS-3171A in DCS panel. The open position of the valve is indicated by 305-XZH-3171 and the close position is indicated by 305-XZL-3171. If the valve has not reached the requested position within 20 seconds, then an alarm is indicated by 305-XZIM-3171 on the DCS panel. 12.6.1.9 Glycol Circulation through TEG Regeneration and Gas Dehydration Column 1.

The process gas flow is established through the Gas Dehydration Column soon after the Glycol circulation. It is also important to circulate glycol through 305-C-001 before the gas is introduced and then contactor is pressurized. Experience have shown that too long a circulation of Glycol in the Gas Dehydration Column without process gas counter-flow could cause foaming. As a result of this, process gas flow shall be established through the Gas Dehydration Column soon after the glycol circulation.

2.

Observe the following parameters: 

Pressure and temperature profile along the unit



Operating levels in the Gas Dehydration Column process vessels



Pressure drop across glycol filters



Pressure drop inside contactor (across the structured packing)



Operation of glycol pump



Glycol flow rate

12.6.1.10 Gas Introduction in Gas Dehydration Column 1.

Introduction of process gas through 305-C-001 should be established soon after the hot glycol circulation is established to avoid potential foaming problem in the




column. Feeding the feed gas to the Gas Dehydration Column should be as smooth as possible. 2.

Increase the feed gas rate in steps of 25% of the maximum flow, each step reached in 30 seconds or more.

3.

As the process gas feeds the internal Gas/Liquid separator of the Gas Dehydration Column (the bottom section of the Column), the water droplets trapped will form a level at the bottom of the Contactor. When the level is above LLLL trip, open the shutdown valve 305-XV-3001 and put in service the control valve 305-LV-3013. The level control valve (305-LV-3013) can be put into service in Auto with the Level Controller 305-LIC-3013.

4.

Continue routing dehydrated feed gas to HP Flare via 305-PCV-3024. Send gas samples for analysis of water content. Slowly rise the gas feed rate up to 50% of design gas feed rate.

5.

Coordinate with the Ash-Shaer Well head Personnel and maintain the choke valves so as to maintain a pressure of 50 barg at the Gas dehydration Column. Set the lean Glycol flow to 4.5 m3/h. 

Maintain a constant temperature of gas feed at 50°C (LP mode) as indicated by 305-TI-3019. Accordingly maintain the lean Glycol temperature of 55°C i.e., 5°C above the inlet gas temperature to avoid hydrocarbon condensation. The temperature is maintained by dry gas/lean glycol heat exchanger



Collect samples at the outlet of the Gas Dehydration column SC-502 to find out the dew point and the water content of the dehydrated gas.

12.6.1.11 Lining up TEG Reflux Condenser into Service (305-E-003) 1. The TEG Reflux Condenser 305-E-003 is considered in service when: 

Water is boiled off glycol at the TEG Reboiler and water & aromatic vapours pass on to the tube side of the reflux exchanger.



Cold rich glycol from the glycol absorber passes through the shell side of the exchanger and partly condenses the water vapours.

2. Too much reflux (condensation) will overload the reboiler; too little reflux or no reflux will increase the glycol losses. For adjusting the reflux rate, it is necessary to control the flow of Glycol through the reflux exchanger by a 3-way control valve.




3. The temperature of the vapours leaving the still column is monitored by 305-TI-3103 (readable in Local) and from 305- TIC-3102 in DCS. The top temperature of the vapours leaving the still column is maintained at 95C by automatically controlling the flow of Rich TEG from the Gas Dehydration Column to TEG reflux condenser. The rich TEG on the shell side cools the vapours in the TEG Reflux Condenser by the 3-ways control valve 305-TV-3102. The control valve 305-TV-3102 will bypass the glycol entering the Reflux condenser 305-E-003. 4. The normal top operating temperature of the Reflux Condenser will depend on the condensation temperature of the vapours. This in turn depends on the amount of hydrocarbon vapours present along with the water vapour and therefore the partial pressure of the water vapour. This temperature has been estimated at 93–98°C depending on the amount of hydrocarbon. Water absorbed by the glycol in the absorber will be boiled off from the glycol at the TEG Reboiler reflux coil. 12.6.1.12 Filtration of Glycol 1.

When TEG Catridge Filter or TEG Carbon Filter will be plugged, the pressure differential across the filter is readable on DCS by 305-PDT-3216/3122 for cartridge filter and 305-PDT-3218 for carbon filter will increase.

2.

When the differential pressure reaches 0.8 bar, then it is necessary to put the ‘standby’ filter is taken into service.

Filter Change-over Operation (Cartridge Filter) 

Open the upstream and downstream valves of the ‘Standby’ filter and open the ¾” vent valve; the ‘standby’ filter is in service.



The service filter can be isolated from the process by closing its own upstream and downstream valves and drained. No relevant effects on hydrocarbon content are expected during filter by-pass time.



Cartridges or carbon loads shall be replaced with new ones at that time. Estimated by-pass time required for cartridge replacement is two hours. Carbon filter is bypassed during change-over of carbon cartridge.

NOTE: It is advisable to start the glycol package with new sets of cartridges and carbon loads in glycol filters. Also always, maintain new replacement cartridges and carbon loads for the standby filters. During first start-up, cartridges with 25 microns




filtration capacity will be used. For subsequent change-overs, cartridges with 5 microns filtration capacity shall be used. 12.6.1.13 Stabilising Gas Dehydration/TEG Regeneration System 1.

Coordinate with the Well heads to open the choke valves so that pressure of 86 barg is maintained at the top of the Gas dehydration column. Maintain the methanol and corrosion inhibitor injection flow rates as per the design flow of dry gas.

2.

Maintain the lean glycol flow and temperature as per the increase of the gas feed rate in the Gas Dehydration Column. Maintain the lean TEG temperature 5C above the wet gas entering the Gas Dehydration Column.

3.

In case of foaming in the dehydration column, start the anti-foam and the corrosion inhibitor injection to various points in the TEG regeneration system.

4.

Stabilise the TEG regeneration system with temperatures and flows optimised for efficient operation of the gas dehydration system.

5.

Hazop Action No. 767 Check for potential leaks in the glycol circuit and arrest leaks on TEG lines wherever possible. Look for potential leaks like foaming in Contactor, escape of TEG vapours from TEG Reflux Condenser and Glycol pump gland leaks and top up when required. If the Glycol surge drum level reaches the LLLL value (305-LALL-3116) of 300mm, it will cause tripping of Glycol Pumps. Loss of Glycol circulation will lead to off-spec dehydrated gas as indicated 305-AIH-3022. Due to this water carryover it will cause accelerated corrosion of the trunk line. In case of losing glycol circulation and initiation of off spec gas alarm 305-AIH-3022 the operator has to initiate ESD-3 trip of Gas Dehydration Package.

6.

Check two or more samples to confirm the water content of the dry gas and Condensate.

7.

It is recommended to have frequent analysis of Gas and Glycol. It is very important to check the glycol concentration at surge drum outlet, gas water content at Gas Dehydration Column inlet, Glycol pH at Surge drum outlet periodically. pH values should be maintained between 7.0 & 8.0.

8.

Hazop Action No. 766 Operator should inspect the Vent Gas KOD (305-V-003) level by monitoring liquid level of KOD at regular intervals by observing level gauge 305-LG-3135. Check the




Liquid trap installed on the drain line of the Vent Gas KOD for its operability. Ensure to drain the liquid periodically with care to avoid gas blow-off. If the liquid level is higher it should be drained to avoid carryover to Vent Gas Blowers (305-K-002A/B/C/D) and causing potential damage to the Vent Gas Blowers. 9.

After the condensate and the dry gas meets the specifications, route both to the GTP trunk line.

10. Hazop Action No. 42 During the Start-up phase, the Gas Dehydration pressure is controlled by operating 305-PV-3024. After stabilization of unit, the Dehydration column pressure control is switched over to Split Range controller 305-PIC-3009. In case of inadvertent action to open 305-PV-3024 fully, will result in depressurisation of the Dehydration Column. This lower pressure will lead to lower efficiency of the Dehydration column. The following trouble shooting points alerts the Operator in case of inadvertent opening of 305-PIC-3024: 

The operator will be alerted at 80.6 barg by Low pressure alarm 305-PAL-3009 and should take immediate action to identify the cause and close 305-PV-3024



High flow alarm in the Flare Header by 331-FAH-5126.



The bigger control valve 305-PV-3009A closes fully and the pressure is controlled only by smaller control valve 305-PV-3009B

However if the Operator does not respond to the above mentioned alarms at 80.6 barg, then at 76.3 barg, the actuation by 305-PALL-3012 will cause ESD-3 shutdown which will cause unnecessary flaring at the upstream section of GGS. Hazop Action No. 47 The ESD-3 shutdown of Gas Dehydration/TEG Regeneration unit closes 305-XV-3001, the TEG Column 305-C-001 Bottom liquid outlet ESD valve. After the ESD shutdown the steps of glycol circulation, Heat-up of Glycol and the pressurisation of feed gas and the other requirements are to be followed as given below in Section 12.6.2. If the glycol circulation, Gas pressurisation and other set of requirements are not followed, it will lead to foaming which will cause glycol carry over to the trunkline. 12.6.2 Start-up at normal conditions Subsequent start-up after a normal shut down requires less operations of a first start up, since the operating parameters should be already set to their correct values.




The following sequence can be followed: 1.

Assure that all the operating parameters (i.e. levels, pressures, etc.) are correct and the plant is ready for start-up.

2.

Check that no causes of shut down are present.

3.

Check the pressures of the Gas Dehydration column 305-C-001 to be at least up to 7 barg.

4.

Check the pressure of the Flash Drum 305-V-002 to be 3.8 barg.

5.

Check the pressure of the Fuel Gas KO drum 305-V-004 to be 5 barg.

6.

Drain the blowers casing of the selected Vent Gas Blowers 305-K-002 A/B or C/D by opening the eight ball valves installed on each blower case assuring that all the possible present condensate vapour inside is drained off before burner ignition, then close the drain valves.

7.

Start the burner from the Local Control Panel or DCS.

8.

After performing the burner start-up, progressively increase the set point of the temperature indicating controller 305-TIC-3109 by DCS, then if the temperature in the reboiler is lower than 90°C. 

Open the valves on the Start Up line 2”-305-GY-1015-11A-P and start the glycol circulation starting a pump allowing the warm-up of the Reboiler and Surge Drum.



When the temperature inside the Surge Drum reach approximately 90°C, open the valves on the start-up line 2”-305-GY-1023-11A-P and close the ones on line 2”-305-GY-1015-11A-P allowing to warm up also the Flash Drum and the filters. This will allow all equipment to slowly warm-up and will avoid thermal shock. When the temperature inside the reboiler reaches 150 °C, can start the Glycol circulation on the Gas Dehydration Column 305-C-001.



If the temperature in the reboiler is already above 90°C, warm up can be avoided.

9.

Open the shut down valve 305-XV-3003 and then close the valves on the recirculation line previously opened (globe valve first then the ball valve). The pressure on the pump outlet line will increase up to the required pressure and allow the glycol to enter the column.

10. Then open the shut down valve on the outlet line 305-XV-3002. The level inside the chimney tray shall be controlled by the valve 305-LV-3017. The glycol




circulation is complete and the glycol temperatures should reach the design values. 11. Put the stripping gas in service by manual opening from DCS the shut down valve 305-XV-3171 on the stripping gas line. 12. Start circulation of process gas through the Glycol contactor soon AFTER the glycol circulation is established to avoid potential foaming problem in the column. Feed the glycol contactor with the process gas as smooth as possible. 13. It is not possible to indicate an accurate value on the feeding rate, it is advisable to have few steps of 25% of the maximum flow, each step being reached in 30 seconds or more. As the process gas feeds the internal gas/liquid separator of the glycol contactor (the bottom section of the column), the water droplets trapped will form a level at the bottom of the Contactor. When the level is above the LLLL trip, open the shut down valve 305-XV-3001 and put in service the control valve 305-LV-3013. Note: During heating the following parameters must be strictly followed: 

Increase the temperature in the reboiler at a maximum rate of 60°C per hour.



Do not exceed 204°C in the reboiler.

The start up sequence is complete and the plant is in operation. 12.7

Start-up of TEG Incinerator System

The start-up of the incinerator involves the following steps: 1.

Combustion Chamber purge by Incinerator Air fan 340-K-001A/B.

2.

Pilot burner lighting.

3.

Main Burner lighting.

4.

Combustion Chamber Pre-heating.

5.

Waste gases feeding after combustion chamber temperature reaching to 750C.

6.

Combustion chamber temperature increasing up to pre-set operating value (850°C)

7.

Dilution Air damper controlled by low value of Oxygen Analyzer and high combustion chamber temperature.

8.

Normal operation.

12.7.1 Pre-requisites before starting the TEG Incinerator The Start-up sequence cannot be carried out if the following lock alarms are on:






ESD system checks whether there is main burner start check failure BSL-6051 & BSL-6048 and detection of the burner main flames (alarm BAX-6051 and BAX-6084) before the opening of the gas valves XV-6033A & XV-6033B and closing of the vent valve XV-6033C.



ESD system checks whether there is pilot flame detection, start check failure BSL-6070 before pilot ignition trial. Also, ESD checks if there is detection of the pilot flame (alarm BAX-6070) before the start of its ignition



ESD system checks whether the air fan is not running before giving the start command of the system.

Start-up of the TEG Incinerator The TEG incinerator is manually started from the field by operator by means of the pushbutton HS-6052B or from DCS by pressing HS-6052A and enable sequential start-up of the incinerator. The start-up follows the sequence as listed below: 1.

Press the field push-button HS-6052B if none of the lock alarms listed in the previous point 12.6.15 is appearing on the system.

2.

The ESD signal starts the air fan 340-KM-0001A.

3.

Air fan 340-KM-001A is started and the sequence checks whether the air fan is running.

4.

ESD checks whether the combustion air pressure PALL-6030 is not in alarm condition after a short time period of 40 seconds (this alarm is overridden for 40 seconds from the time of starting the air fan).

5.

DCS signal to FY-6031 fully opens air valve FV-6031.

6.

Starts purge timer after FT-6031 confirms adequate purge airflow rate. During purge time, LCP will illuminate ‘Purge On’ lamp XL-6060.

7.

After completion of purge time ‘Purge Complete’ lamp XL-6061 will illuminate in LCP (Local Control Panel).

8.

Starts ignition transformer and continues sparking for 10 seconds. 2 seconds after ignition has started, pilot valve XV-6032A, XV-6032B and XV-6032C are activated.

9.

ESD checks Pilot flame detection and de-energizes ignition transformer (both have preset time periods). If the flame is not detected, it de-energizes XY-6032A, XY-6032B and XY-6032C and raises an alarm.




10. When the pilot flame is detected, it illuminates ‘Pilot On’ lamp XL-6063 and commences 20 seconds flame establishment period. 11. This is followed by activation of the main fuel gas valves XV-6033A, XV-6033B and XV-6033C. 12. ESD checks whether main flame scanner has detected the flame and informs LCP that the main flame is ON; ESD will enable ‘Main Flame Present’ indication lamp XL-6051. 13. ESD will enable PAHH-6056 function. 14. Heat incinerator up to a operating temperature of 750C. 15. DCS will send a signal to ESD (via HS-6055A) to activate valve XV-6041A, XV-6041B and XV-6041C (TEG Off-Gas). 16. DCS will send a signal to ESD (via HS-6056A) to activate valve XV-6045A, XV-6045B and XV-6045C (Produced Water Tank Off-Gas) 17. Once the burner is in operation, the next step is to increase the combustion chamber temperature up to the minimum value for Off-Gas injection (pre-heating of the incinerator). A temperature ramp-up control gradually heats up the combustion chamber over a time period (to prevent thermal shock of the refractory due to full burner output when refractory is cold). 18. The steps of off-gases feeding to incinerator are the following: 

Minimum TT-6047 temperature value for gas injection is reached after establishment time of 10 min;



Opening TEG Off-Gas valves XV-6041A & XV-6041B and closing XV-6041C to consent off feed.



Opening Produced Water tank Off-Gas valves XV-6045A, XV-6045B and closing XV-6045C to consent off feed.

In case of burner shut-down for any reason or incinerator low temperature TI-6047, the valves of TEG off-gas and Produced Water tank off-gas close immediately. 

Open the shut down valve 305-XV-3003 then close the valves on the recirculation line previously opened (globe valve first then the ball valve). The pressure on the pump outlet line will increase up to the required to allow the glycol enter the column then open the shut down valve on the outlet line 305-XV-3002. The level inside the chimney tray shall be controlled by the valve




305-LV-3017. The glycol circulation is complete and the glycol temperatures should reach the design values. 

Put the stripping gas in service by manual opening from DCS the shut down valve 305-XV-3171 on the stripping gas line.



Start circulation of process gas through the glycol contactor soon AFTER the glycol circulation is established to avoid potential foaming problem in the column.



Feed the glycol contactor with the process gas as smooth as possible.



Despite it is not possible to indicate an accurate value on the feeding rate, it is advisable to have few steps of 25% of the maximum flow, each step being reached in 30 seconds or more.

As the process gas feeds the internal gas/liquid separator of the glycol contactor (the bottom section of the column), the water droplets trapped will form a level at the bottom of the Contactor. When the level is above the LLLL trip, open the shut down valve 305-XV3001 and put in service the control valve 305-LV-3013. Note: During heating the following parameters must be respected: 

Increase the temperature in the reboiler at a maximum rate of 60°C per hour.



Do not exceed 204°C in the reboiler.

The start up sequence is complete and the plant is in operation. 12.7

START-UP OF OILY WATER SYSTEM

12.7.1 Line-up of Oily Water System The Oil-water system comprises of the open drain sump and the oily skimmers. The source of water is mainly the water from the Well heads and floor washings from the process system and the sample points. 1.

Line-up the waste water to a Produced Water Degassing Drum (334-V-001)

2.

Ensure the Produced Water system is ready for start-up as detailed in Section 11.13 above

3.

Ensure to line-up blanketing gas (Fuel Gas) to Degassing Drum and Produced Water storage tank

4.

Ensure water separation in Production Separator 302-V-001 and the level controller 302-LIC-1114 is lined up to 334-V-001


5.



Take 302-LIC-1156 on Manual and separated water at the boot of Coalescer 302-F-002A/B to Produced Water Degassing Drum. Set the level at 50% and take the controller on Auto

6.

Check the level build-up in degassing drum

7.

Set the level controller 334-LIC-3441 at 50% and take it on Auto. Check flow of water to 334-T-001

8.

Ensure the tank is always kept under fuel gas blanketing and the pressure is maintained by 334-PV-5409

9.

Line-up open drain contaminated pump to Produced Water storage tank

10. Ensure 334-V-001 is pressure is controlled by 334-PIC-5449 and off-gas flows to flare 11. Observe the separation of hydrocarbon condensate at the top surface of water 12. Skim off HC condensate manually to closed drain by monitoring the interface level at 334-LI-5400 13. The separated water from the produced water tank is disposed off to tankers using Produced Water disposal pumps 334-P-001A/S.




13.0 NORMAL OPERATION AND MONITORING


13.1



PRODUCTION SEPARATOR NORMAL OPERATION

The following are to be maintained and controlled for stable operation of Production Separator: o

Monitor the operating pressures, liquid levels and production rates of condensate, gas and water (measured by the flow meters in respective lines) of separators.

o

Ensure that the pressure and level controllers of Production Separator are in Auto mode. The operating pressure of the Production Separator shall be steady under normal operating conditions. In case of frequent variations, check the functioning of the pressure and level controllers.

o

Ensure that all methanol injection systems are running and the chemicals are injected at the required rate during winter.

o

The vapour and liquid flows to and from the Production Separator may change depending on the variation in Gas to Oil Ratio (GOR) of the production fluid and the change in operating conditions of the plant like turndown etc.

o

Ensure that liquid level in the oil compartments is steady.

o

Regularly check and ensure that the drain valves of Production Separator are closed and the spectacle blinds are in closed position

o

Periodically cross-check the levels, temperatures and the pressures of the Production Separator between control room and field wherever possible. Any discrepancies should be rectified.

o

Ensure free flow of produced water. Check heat tracing on regular basis. Prevent maintenance of H.T.Coil shall be done as per schedule.

o

The pressure is maintained at 86.75 bara during the HP mode and 26.85 bara during the LP mode. The pressure in the Production Separator is controlled by back-pressure of the gas dehydration column. If for any reason, the Production Separator increases beyond 86.75 bara, then the pressure control valve 302-PCV-1137 will open to flare to maintain normal pressure. If the pressure still increases and leads to popping of Production Separator PSV, the choke valve opening can be adjusted or isolate one of the well heads to control the pressure immediately. If the Production Separator pressure reduces, this may be due to tripping of any well head and can be normalised by restarting the well head after




attending its fault. If the pressure is still low, then adjust the choke valve opening to get normal pressure in the Production Separator. The interface level is maintained by the Interface Level Controller 302-LIC-1114

o

which controls the Produced Water flow through 302-LV-1114 to Produced Water Tanks. The interface level is maintained at a normal level of 650 mm. If the interface level increases quickly, this may be due to increased production flow of gas or increased water content of the well head fluids. Sometimes the bypass of the control valve 302-LV-1114 is operated to control the increased level of water level in the Production Separator. Key Performance indicators for Production Separator and Coalescer Circuit Tag No. 302-PI-1112 302-TI-1138 302-FI-1108 302-LIC-1119 302-LIC-1114 302-FI-1106 302-FIC-1182 302-PDI-1168 302-PDI-1169 13.2

Description Production Separator pressure Production Separator Gas temperature Gas flow to Gas Compressor/Gas Dehydration Column Production Separator Condensate level Production Separator Interface level Production Separator Water flow rate Condensate flow rate Differential pressure for Coalescer 302-F-002A Differential pressure for Coalescer 302-F-002B

Required Value 86.75 42 131.0 50.0 50.0 40.0 36.0 0.2 0.2

Unit bara °C Sm3/h % % m3/h m3/h bar bar

GAS DEHYDRATION & TEG REGENERATION SYSTEM

The following are the main points for periodical checks of the normal operation of Gas Dehydration and TEG Regeneration system.

o

Maintain the lean glycol flow and temperature as per the increase of the gas feed rate in the gas dehydration column. Maintain the lean TEG temperature 5C above the wet gas entering the gas dehydration column. Adjust the final parameters so that the final moisture content of the dry gas is met.

o

Pressure drop across the Gas dehydration column should have a normal value of 0.2 to 0.3 bar. In any case, if the differential pressure reaches 0.35 bar, then it indicates foaming problem in the dehydration column. Collect both lean and rich glycol samples frequently to determine the purity of glycol and eliminate foaming.


o



Vaporisation losses in the regenerator still column can be reduced by satisfactory glycol condensation. Monitor the reflux condenser outlet temperature and maintain it at a temperature of 95C. Also, maintain the temperature of lean glycol within 3 to 6°C to the inlet gas temperature. Avoid excessive gas velocities which will lead to foaming by reducing the gas feed appropriately.

o

During winter months when air temperature might fall to –15°C (minimum ambient temperature), ensure heating the Gas dehydration column bottom, condensate outlet line and the chimney tray of the gas dehydration column – these are heated by electrical tracing.

o

When there is foaming in the column, start the antifoam and the corrosion inhibitor injection to various points in the TEG regeneration system

o

Stabilise the TEG regeneration system with temperatures and flows optimised for efficient operation of the gas dehydration system.

o

Check the two or more samples to confirm the water content of the dry gas and condensate.

o

Do not operate the glycol reboiler above 204°C as it will lead to premature glycol degradation.

Chemical Requirement o

The estimated TEG make-up requirement is 400 kg once a week.

o

Antifoam requirement is 10 litres per week. Regular TEG chemical analysis will determine the exact requirement.

o

Corrosion Inhibitor requirement is 10 litres per week. Glycol pH will determine the exact requirement.

Key Performance Indicators for Gas Dehydration System and TEG Regeneration System Tag No. 305-TI-3019 305-LIC-3017 305-LIC-3013 305-PIC-3009 305-PDI-3007 305-TI-3076 305-FI-3113 305-TIC-3102 305-TI-3101 305-TG-3100

Description Gas Inlet to 305-C-001 Temperature Lean TEG level in 305-C-001 Bottom Condensate level in 305-C-001 305-C-001 Top pressure 305-C-001 Packing differential pressure Lean TEG to 305-C-001 Lean TEG flow to 305-C-001 OVHD temperature of 305-E-003 Rich TEG temperature to 305-E-003 Rich TEG Inlet temperature to 305-E-001

Required Value Unit 50.0 C 50.0 % 30.0 % 84.8 barg 0.3 bar 55 C 6.0 m3/h 95 C 53.5 C 62.0 C



Tag No. 305-TG-3119 305-TG-3144 305-TG-3127 305-LIC-3210 305-PDI-3216 305-PDI-3222 305-PDI-3218 305-LI-3115 305-TIC-3109 305-PI-3178 305-PI-3174 305-PI-3189 13.3 


Description Rich TEG Outlet temperature from 305-E-001 Lean TEG Inlet temperature to 305-E-001 Lean TEG Outlet temperature of 305-E-001 Flash drum TEG level 305-F-003A Differential Pressure 305-F-003B Differential Pressure 305-F-002 Differential Pressure Lean TEG Surge drum level TEG Reboiler vapour temperature Stripping gas pressure Main TEG Burner FG pressure TEG Pilot burner FG pressure

Required Value Unit 150.0 C 103.0 C 73.8 C 50.0 % 0.2 bar 0.2 bar 0.15 bar 50.0 % 204 C 0.4 barg 0.5 barg 0.3 barg

COMPRESSOR NORMAL OPERATION

Ensure all control and safeguarding functions of the Field Gas Compressor and its auxiliaries are normal.



Check vibration and displacement at the compressor monitoring system and Human Machine Interface (HMI).



Monitor the functioning of anti-surge control system



Check the compressor suction pressure at 304-PT-1221.



The suction pressure controller sends a speed set-point signal to the VSDS (Variable Speed Drive System).



The VSDS tends to decrease the speed of the compressor in case the suction pressure is decreasing below the set point.

Lube Oil The Lube Oil Reservoir temperature is controlled by 304-TIC-1527 which controls the heater by a thermister control which switches the heater ON and OFF at a desired temperature. The lube oil header temperature is maintained at 59°C by a temperature controller acting on a three-way valve 304-TCV-1503 which bypasses the lube oil across the lube oil cooler (304-X-1500). The lube oil supply pressure is controlled by self-actuated pressure control valve 304-PCV-1510 which maintains the header pressure at 2.5 barg by opening to the Lube Oil Reservoir. Seal Gas 

Ensure the seal supply pressure and temperature are maintained



Ensure seal leak monitored by the back pressure controller 304-PV-1464





Monitor the seal gas filter pressure drop at 304-PDI-1451



Check the nitrogen bottle availability


Compressor 

Check condensate level in the suction KO drum is controlled. Check the secondary seal air pressure and quality.



Monitor the suction and discharge pressure of the compressor



Monitor the bearing temperature



Ensure field gas compressor cooler fans are running and the gas temperature is controlled at 60C

Early Plant (HP) Operation During this mode, the suction KO drums, the Field Gas Compressors and their Aftercoolers will be bypassed. Hence, all controllers, as listed on the next page, related to the suction KO drums, the Field Gas Compressors and the Aftercoolers shall be forced to ‘Manual’ and outputs driven to 0% during HP mode operations. 304-TICA-1268 304-TICA-1275 304-TICA-1215 304-LIC-1210 304-TICA-1368 304-TICA-1375 304-TICA-1315 304-LIC-1310

Field Field Field Field Field Field Field Field

Gas Gas Gas Gas Gas Gas Gas Gas

Compressor Aftercooler-A louver control (bay-1) Compressor Aftercooler-A louver control (bay-2) Compressor Aftercooler-A outlet temperature control Compressor Suction KO Drum-A level control Compressor Aftercooler-B louver control (bay-1) Compressor Aftercooler-B louver control (bay-2) Compressor Aftercooler-B outlet temperature control Compressor Suction KO Drum-B level control

In addition to the above, the compressor faceplate for DCS operations like compressor start sequence, compressor motor start, lube oil standby pump start and lube oil coolers start shall be disabled during HP mode.




14.0 PLANT START-UP AFTER EMERGENCY SHUTDOWN


14.1



GENERAL EMERGENCY SHUTDOWN LEVELS - ESD1, ESD2 & ESD3

The ESD levels adopted for the facilities are as follows: ESD Level -1 Shutdown: ESD Level-1 shutdown will open all the depressurizing

o

valves at the same time. ESD Level-2 Shutdown: ESD Level-2 shutdown will enable depressurization,

o

allowing for operator action if required. ESD Level-3 Shutdown: ESD Level-3 shutdowns are used only to isolate or

o

shutdown systems. Individual unit/equipment may be depressurized if necessary. Whenever any ESD is initiated either by the process conditions or by the operator, all the ESD outputs will be de-energized and final control element are driven to fail safe position. ESD system will maintain this fail safe position as long as ESD condition persists. Even after ESD initiating condition becomes normal and as long as manual reset for individual output is not given by operator, ESD will hold the fail-safe position. Once the operator initiates reset for individual tags (through DCS graphics), ESD will drive those outputs to normal state (i.e. State 1). If the trip is initiated by ESD Level-2 or ESD Level-3 shutdown, then the plant can be started immediately after manually resetting the ESD by the Control Room Operator provided the parameter which had initiated abnormal process condition returns to normal value. If it is ESD Level-1 shutdown, then after ensuring the reason for abnormal condition, the CCR Operator should confirm with the operator concerned whether the condition has returned to normal before proceeding with the start-up of the unit. For the normal start-up of the unit after depressurization, follow Section-12. However the initial purging and the pressurization of the unit need not be followed and proceed with starting the various motors equipment and stabilisation of the unit. For the ESD Level-2 and ESD Level-3, the plant can be started directly with only stabilising of the unit. 14.2

PLANT START-UP AFTER ESD1 SHUTDOWN

If it is ESD Level-1 shutdown, then after ensuring the reason for abnormal condition, the CCR Operator should confirm with the operator concerned whether the condition has returned to normal before proceeding with the start-up of the unit. EDG is stopped or not getting started (Due to confirmed presence of 10% LEL) Ensure the plant normalcy is returned and cleared by the supervisor for restart-up of the plant. PLANT START-UP (EDG not available due to presence of LEL > 10%) 1.

Ensure the cause for ESD level-1 shutdown.

2.

Take all Level Control Valves and keep them closed. Take Pressure Control Valves and keep them closed or control the pressure as the process warrants.


3.



Ensure LEL 10% level at HVAC suction or 20% level at field is not active. Signal is healthy.

4.

Check DCS and safety system are healthy with power supply from UPS.

5.

Check battery system is healthy and lube oil is powered. EDG control supply is available.

6.

Rest ESD1 button by pressing ‘ESD level 1 RESET’ at Control Room.

7.

Ensure all blowdown valves are closed. Check the indication at DCS.

8.

Start Emergency Diesel Generator a.

Check the diesel level in the day tank. Ensure the Emergency Diesel Generator Local control Panel is powered from the battery

b. 9.

Start the EDG as detailed in Section 5 of this manual

Start-up shall be done as detailed below.

14.2.1 Start-up of Utility Water Systems






Ensure 326-P-003A/B utility water pump is ready for start-up



Ensure lubrication for the pumps



Ensure valves at utility water points are closed



Ensure power supply to 326-P-001A/S borehole water pump



Start 326-P-001A/s from local pushbutton and check the discharge pressure at 326-PG-4731



Check the water flow at 326-FI-4726 to utility water tank



Set 326-LIC-4760 to Auto mode



326-LIC-4760 gives command to 326-P-001 borewell pump to start at Low level

14.2.2 Start-up of Potable Water Systems



Ensure Potable Water Tank 326-T-003 has adequate level






Ensure valves at potable water points are closed



Ensure suction strainers for 326-P-005A/B potable water distribution pumps are cleaned and reinstated



Check the pump 326-P-005A shaft is free






Energise 326-P-005A






Open pump discharge valve and control the discharge pressure at 4 barg



Charge the potable water distribution header



Header pressure is maintained by controlling 326-PV-4786 in the recycle line to potable water tank



Keep 326-P-005B as standby pump

14.2.3 Start-up of Plant Air System



Ensure drain valve and bypass valve for Plant Air Receiver 325-V-001 are closed



Ensure all instruments are lined up to DCS (No change made since shutdown of the plant-ESD1 activation)



Open 2” vent valve on Plant Air Receiver 325-V-001 and close outlet valve



Open inlet valve to 325-V-001 Wet Air Receiver on discharge of compressor



Open inlet valve of 325-V-001 Wet Air Receiver



Ensure compressor after cooler is lined up



Confirm that compressors are set for local control



Following the start-up procedure as per the vendor’s Installation, Operation and Maintenance Manual. Start Compressor No. 1 from local control panel.



Confirm lube oil circulation and check operation of the lube oil separator



Check the compressor for abnormal conditions (pressure, temperature, noise, etc.)



Once the compressor is started, slowly pressurize the plant air receiver 325-V-001



Ensure all isolation valves in the field utility station are closed



Close 2” vent valve and blind it. Open outlet valve of 325-V-001 for admitting Plant Air to the system network



Ensure plant air user valves are closed



Open 325-XV-4665 at the outlet of 325-V-002 plant air receiver



Line-up 325-PV-4660 manually and charge the plant air header. Check the flow at 325-FI-4663






Set 325-PV-4660 at 8.5 barg and take the controller on AUTO mode

Refer vendor operating and maintenance manual for further details. 14.2.4 Start-up of Instrument Air



Select Instrument air Dryer to be on line from the Selector switch. Line-up 325-X-002A; 325-X-002B goes to Standby mode



Line-up plant air to IA Dryer 325-X-002A



Open the outlet valve 325-X-002A of instrument air dryer to instrument air receiver 325-V-002



Ensure 325-XV-3275 in IA line to nitrogen is closed



Line-up all instruments to DCS



Start the Instrument Air Driers as per vendor operating and maintenance manual



Controls from Local Panel for steady operation of the compressor



Ensure drain valve and bypass valve for Instrument Air Receiver 325-V-002 are closed



Open inlet valve of 325-V-002



Check instrument air pressure at 325-PI-4661



Close 4” vent valve and blind the pressure. Open outlet valve of 325-V-002 for admitting instrument air to the system network



Monitor compressor discharge pressure, dryer pressure drop, change-over of dryers, and the dew point of dried air; log data on a daily basis

Refer vendor’s operating and maintenance manual for further details Normal Operation Ensure Plant Air Compressor is operating normally. Check pressure and flow rate of IA at DCS. Ensure the dew point –35C at 7.5 barg is maintained through on-line analyser. The following are set for the Auto-Start of the Running Compressor and Start/Stop of the Standby Compressor: Unload Compressor-B Unload Compressor-A Load Compressor-B Load Compressor-A

: 8.6 : 8.4 : 8.0 : 7.7

barg barg barg barg



Plant Shutdown


: 4.5 barg

14.2.5 Start-up of Nitrogen System



Ensure power supply from EDG set and MCC is energised



Energise Local Control Panel



Ensure pre-requisite activities of nitrogen generator, nitrogen receiver and other utility systems are completed



Ensure the instrument air receiver is under normal pressure (7–9 barg)



Check instrument air dew point and confirm it is within specification limits (–35°C at 7.5 barg)



Ensure all instruments are hooked up to DCS



Open 2” valve at the inlet of 324-X-001 nitrogen package



Reset 325-XV-4725 and admit IA to nitrogen membrane unit 324-X-001



Line-up nitrogen membrane units 324-M-001, 324-M-002 and 324-M-003



Ensure to line-up the inlet block valve and outlet ball valve of the membrane units 324-M-001, 324-M-002 and 324-M-003



Ensure the analysers 324-AIT-4619 and 324-PCV-4612 are lined up to DCS



Start membrane unit from Local Control Panel



Line-up product block valve



The product will automatically be vented through the product vent valves 324-XV-4620 & 324-HCV-003 until on-specification N2 (98% purity) is generated



Adjust purity control valve until the purity of product nitrogen is achieved



When the O2 level in N2 product stream reaches 2%, the system will automatically switch product valves 324-XV-4616 and 324-HCV-002 to open and product vent valves 324-XV-4620 & 324-HCV-003 to close

Refer vendor operating & maintenance manual for further details. Line-up Nitrogen Receiver



Ensure drain and vent for the receiver 324-V-001 are closed



Open block valve in the product outlet line from nitrogen generator and slowly admit nitrogen to the receiver 324-V-001






Pressurize the receiver and vent the nitrogen through drain from the receiver



Open outlet valve for the receiver and charge the nitrogen header



Change controls of nitrogen generator from local control panel to DCS



Check the controls of nitrogen generator, both on Manual and Auto from PCS



Monitor nitrogen purity

Normal Operation of Plant Air, Instrument Air & Nitrogen Systems



Line-up plant air header from instrument air receiver 325-V-002 by opening 325-PV-4660



Set 325-PICA-4660 at 7 barg and take the controller on Auto



Line-up master pressure controller 325-PT-4732 on Auto



Monitor the operation of plant air , instrument air and nitrogen systems; keep them running for the start-up of the plant

14.2.6 Start-up of Flare System



Ensure lining up of all instruments in flare headers, Flare KO Drum, Flare KO Drum Booster Pumps and KO Drum Pumps (Normally not disturbed after ESD1 shutdown)



Check the seal oil for the KO Drum Booster Pumps



Check the lubricant for the booster pumps 331-P-001A/B



331-X-001 Flare shall be lit as per vendor start-up procedure (if the flare is put off. Normally the flare continues with gas hold up in the flare network)



Ensure flare is started with propane gas and keep the flare with propane supply until LP fuel gas system is established



Start the heater if the Flare KO Drum level is above 50%. Start the heater. Line-up all instruments for the heater



Heater shall maintain 50C. The heater will start at 40C and stop at 60C



Start KO Drum Booster Pump 331-P-001A (B as Standby) and keep it under recycle by operating 331-FV-5160 to ensure minimum flow through the pump



Line-up condensate from booster pump to suction of 331-P-002A



Check the operating pressure of production separator



Reset 331-XV-5129 and open the shutdown valve






Keep 331-P-002B as hot Standby (keep both suction and discharge valves open)

14.2.7 Start-up Open Drain System



Start-up after electrical power supply resumed



Keep the pumps energised



Line-up 332-P-001A/S to holding pond and 332-P-002A/S to Produced Water storage tank



Line-up level instrument in holding pond



Ensure holding pond overflow line is clear



Ensure 332-P-003A/S water disposal pump is in running condition

14.2.8 Start-up Closed Drain System All required electrical and instrumentation (including safeguarding) systems required for the drain system is fully tested and commissioned.



Check and confirm that the lube oil level is at the correct level for the pumps



Reset 333-XS-5321 for the heater



Ensure Power Supply to Heater Control Panel and 333-P-001A/B



Set 333-LICA-5304 to AUTO mode. Line-up the pump discharge to 331-V-001 Flare KO Drum



Open 333-P-001A/B Discharge Valves



Open 333-P-001A/B discharge battery limit valve



Ensure the level of liquid is at Low Low level before draining from any process equipment.



Check level in 333-LIC-5304



Drain out the liquid by pump 333-P-001A/B, if the liquid level is above Low Low



Ensure collection of drained liquid (hydrocarbon) above Low Low level



Start Heater E-333-H-001 from DCS



Set 333-TICA-5306 to AUTO mode



Set Point = 50C



Ensure liquid level in the Closed Drain Vessel before starting Heater






Switch OFF the Heater manually from DCS when there is no liquid level in the Closed Drain Vessel

14.2.9 Start-up of Fuel Gas System



The high pressure fuel gas is supplied from the trunk line to power generator packages 323-X-001A/B



Ensure Emergency Diesel Generator is supplying power to GGS (start-up requirement)



Ensure DCS and instruments are lined up



Ensure flare is lined up



Ensure supply of fuel gas from trunk line (large sink of gas)



Ensure valves at the inlet of GTG are closed



Line-up fuel gas through 3” line from trunk line to fuel gas system



Drain the condensate from the pipe line to closed drain header



Gradually open 321-PV-3306 and admit fuel gas to KO Drum 321-V-001



Drain the condensate from the KO Drum 321-V-001 to flare header through the level control valve 321-LV-3311.Take 321-LV-3311 on Auto mode



Line-up fuel gas superheater 321-H-002A



Line-up fuel gas filter 321-F-001A or B



Drain out the condensate from the filter (first time) and close the drain valve



Energise heat tracing



Reset and start the heater 321-H-001A



Set 321-TIC-3352 at 15C and take it on Auto



Ensure gas flow to superheater 321-H-002A



Start the heater 321-H-002A by switch 321-HS-3420



Set heater temperature at 321-TDIC-3323 at 15C and take it on Auto



Check the pressure drop across filter at 321-PDI-3319



Fuel gas is ready to be admitted to GTG



Line-up fuel gas to field gas compressor (seal gas)


14.2.10



Start-up of Gas Turbine Generator

Ensure EGD is running and supplying power to auxiliaries of GTGs. Ensure Instrument air supply is restored. Ensure fuel supply pressure is maintained by the gas from Trunk Line. Energization of 11 kV switchgear at the Substation: The dead bus closing of the bus-tie AB from GTG-A UCP & GTG-B UCP is to be carried out. The ‘breaker close’ command from individual GCP is routed through a close permissive from the PMS which ensures that the 11 kV system is healthy. All incomer and outgoing breakers are in open condition and the switchboard is healthy with no faults. (In Manual mode, 11 kV Incomer and Bus Tie Breakers can be closed in Test position only). Operator to ensure that the 11 kV switchboard is a continuous bus with all bus-coupler breakers closed before starting of the GTGs under plant start-up condition. Identify and start one of the GTGs (either GTG-A, or, GTG-B). The feeders of the GTG-Auxiliaries shall be kept in ready to start condition, so that they can start when the signals are received from the GTG-UCP. The GTG Auxiliaries are: o

Starter Motor

o


o


o


o

Main Enclosure Vent Fan 1 & 2

o


o


o

ABLOC Fan 1, 2 & 3

o

CACA Fan 1 & 2

o


o


o


o


All these feeders are located in the respective Gas Turbine Generator MCC Switchboard fed from the Emergency MCC. The first GTG is brought into circuit by dead-bus closing of its 11 kV incomer breaker. The incomer circuit breaker ‘Close’ command in the GCP is routed through a PMS ‘Close’ permissive contact which will ensure that the NER of the first GTG that is being brought into circuit is connected to the system, thus ensuring that the 11 kV system is earthed. On closing of the first GTG incomer breaker on to the HV switchboard, the 11 kV system gets energized, and the 11 kV bus voltage, kW and current feedback along with breaker status is available to the PMS and selectively to ICSS.




Refer Section 5 of this manual and the vendor operating instruction manual for more details. 14.2.11

Start-up of Produced Water System



Check the level at 3344-T-001 Produced Water storage tank



Line-up all instruments for the Produced Water storage tank



Line-up all instruments for Produced Water degassing drum



Ensure to line-up blanket fuel gas to 334-T-001 by opening 334-PCV-54408



Control the tank pressure by operating 334-PV-5409 to TEG incinerator



Line-up degassing drum 334-PCV-5449 to flare



Take all controllers on Auto



Keep the degassing drum and the Produced Water tank to receive Produced Water ready for operation

Start-up of Methanol System



Check the level at Methanol Storage Tank 329-T-001






Ensure Methanol unloading pump 329-P-001A/S and 329-P-001A/S methanol unloading/loading pump are ready and powered up for plant start-up



Line-up blanketing (LP Fuel gas) gas to methanol storage tank by taking 329-PCV-4905 on line



Control the tank pressure at 100mbarg by 329-PCV-4906 vent valve



Set both control valves 329-PCV-4905 and 329-PCV-4906 to Auto



For top of level in methanol storage tank, unloading shall be done as detailed in Section 11 above.



Check the methanol flow to methanol storage tank. Control the tank pressure



Ensure the tank level is above 50%



Monitor the level at 329-LI-4900



Ensure valves at methanol loading point is closed



Loading of the tote tank is done by running 329-P-001A/S.



Start Methanol Injection as required while starting the plant


14.2.12



Start-up of Glycol Transfer System



Ensure Glycol Storage Tank 305-T-001 is cleaned and ready to receive water






Ensure glycol make-up pump 305-P-002 and TEG drain pump 305-P-001A/S are ready for start-up of the plant after shutdown



Make sure the requirement of glycol in dehydration system



Start 305-P-002 from local pushbutton and check the discharge pressure at 305-PG-4905



Run the make-up pump on recycle to glycol storage tank



Line-up 305-F-001.Open make-up pump

discharge and transfer glycol

to

regeneration section. Stop the pump once the desired quantity is transferred 14.2.13

Start-up of Production Separator



Check the pressure of Production Separator



Ensure blowdown valves are in closed position



Take the pressure control valve 302-PV-1132 on Manual and keep it closed



Keep the level control valves at condensate line and Produced Water are kept closed on Manual



Ensure blowdown valve 302-XV-1109 is taken on line



Ensure the shutdown valves 322-XV-1102, 302-XV-1101 and 304-XV-1200 are in closed condition.



Ensure all instruments are lined up to DCS



Ensure heat tracing for all instruments and process lines



Ensure well head is lined up to ESDV at the inlet to separator



Reset 302-XV-1157 and 302-XV-1100 at the inlet of production separator



Open 302-XV-1157 and pressurize the header up to 302-PV-1156



Gradually open 302-PV-1156 and pressurize the production separator



Check the pressure drop at 302-PDIT-1107 is less than 2 barg



Open 302-XV-1100. 302-XV-1157 closes automatically






As the pressure is increased in the Production Separator, liquid starts condensing in the weir. Establish interface level and after the condensate level reaches the weir height, condensate overflows to the condensate side



Control the separator pressure at 87 barg with 302-PV-1132. Stabilise the separator pressure



Set the pressure controller 302-PIC-1132 to Auto. Continue flaring till stabilising the operation of separator



Commission the condensate level transmitter 302-LIC-1119 and the local level gauge 302-LG-1118; check that both show the same level



After the condensate level 302-LIC-1119 reaches 30% level, this would require the following valves to be opened:

 Force open 302-XV-1102 and line-up condensate to the Early Operation condensate pumps (302-P-002A)

 Suction valve of 302-P-002A  Discharge valve of 302-P-002A 

Pump safety valve 302-PSV-0135A should be car sealed in the open position.



At this time, the plant should have been purged free of air and leak tested to operating pressures.



Start Early Operation condensate pump 302-P-002A and line-up one of the Condensate Solid filters (302-F-001A) and Condensate Coalescer (302-F-002A). Take 305-LCV-1119 in Manual mode and keep it 20% open.

Note: Initial level of condensate can be lined to Closed Drain header and later when the dry gas from Gas Dehydration Column meets specification, it can be pumped back from Closed Drain Drum and Flare K.O Drum to Production Separator and avoid slug accumulation in the GTP trunk line. Line-up of Gas to Fuel Gas System (Separator gas is lined up if gas from trunk line is not available).



Ensure operation of production separator is stabilised



Ensure Fuel Gas system is ready as detailed in Section 11.12 above



Open block valves at the inlet of Fuel Gas heater 321-H-001A/B



Open 302-XV-1207 and charge gas to fuel gas system





Refer Section 11.12 for lining up Fuel Gas

14.2.14




Start-up of the Condensate System

After the condensate level reaches the weir height of the Production Separator, the condensate overflows to the condensate chamber in the production separator 302-V-001.



Ensure all instruments are lined up to DCS and active.



Line-up the suction valves of the condensate pumps 302-P-001A/B (LP Phase) or 302-P-002A/B (HP Phase).



After the condensate reaches the Level Low height of 610 mm on the condensate side of the Production Separator, the ESD valve 302-XV-1102 is forced open and the condensate flows to the suction side of the Condensate Pumps.



Start the Condensate Pump 302-P-001A on minimum-flow line 302-LV-1119.



Line-up the Condensate Solid Filters (302-F-001A) first and pressure up the A-filter. Check the differential filter 302-PDI-1144.



Line-up Condensate Coalescer (302-F-002A) and slowly fill the Condensate Coalescer.



Check the Interface Level Controller 302-LIC-1156A. As level starts to appear as indicated in the level controller 302-LIC-1156A, open the level control valve 302-LCV-1156 manually and maintain the interface level.



Keep the Condensate Coalescer (302-F-002B) as Standby.



Check the condensate samples; once it meets the specification, it can be routed to the GTP trunk line. If there is more delay in the Gas Dehydration and TEG Regeneration system, condensate can be drained to the Closed Drain Drum.



The condensate flow controller 302-FIC-1182 can be kept in cascade with the Production Separator Level Controller 302-LIC-1119.

14.2.15

Start-up of Field Gas Compressor (LP Operation)



Ensure the cause for ESD level-1 shutdown



Ensure the Compressor Discharge Depressurization valve 304-XV-1264 is opened due to ESD-1 shutdown. Reset 304-XV-1264. Keep it closed



The Antisurge valve 304-FV-1212 is in Open condition






Since the Compressor discharge side is depressurised and the antisurge valve is opened, the compressor will be in depressurized condition and the start-up will be like initial start-up



Check the availability of seal gas. Alternatively, use nitrogen as seal gas for the compressor



Line-up seal gas (N2) to the compressor seals



Ensure blowdown of compressor is reset and taken on line



Energise electrical system for compressor as detailed in Section 12 of this manual and also refer the vendor manual



Line-up flare header from compressor



Reset 304-XV-1264. Keep it closed

Line-up of Seal Gas System Line-up Fuel Gas and thereafter the Seal Gas system for the compressor (nitrogen as seal gas if compressor is at settled-out condition). Ensure seal gas pressure is 27 barg. Instrument air (Secondary Seal) Ensure IA pressure is 5–8 barg. Line-up Field Gas Compressor Aftercooler Ensure lubrication for cooler fans; Start the fans and check performance. Take 304-TIC-1213 on Manual. Set the temperature at 60C. Line-up Lube oil system. Start-up of Compressor



Ensure pre-requisite for compressor start-up is completed



Ensure DCS, antisurge control system, temperature monitoring system and condition monitoring system are lined up as per vendor’s instruction manual



Check the operation of antisurge valve 304-FCV-1212 and flare vent valve 304-PCV-1294 from the local control panel



Ensure healthiness of seal gas system and lube oil system



Ensure healthiness of motor local control station, remote control panel, ESD panel, compressor PLC system and VSD switchgear






Power up VSD and check the readiness of motor (Check that the interlock for startup is active). Refer operating instruction manual of the vendor

Charging of Gas to Compressor



Ensure the compressor is at locked up pressure or completely depressurized after ESD1 level shutdown



Ensure gas pressure at separator is 27 barg or greater



Ensure to line-up KO Drum 304-V-001A. Take 304-LIC-1210 on Auto



Ensure compressor discharge valve is open



Reset 304-XV1219 at compressor discharge and keep it closed



Reset 304-XV1200/1201 at KO drum inlet



Select the compressor start-up in ‘Sequence’ Start-up Mode



Line-up antisurge control system. Open 304-FCV-1212



Open ESD-V1201 and admit gas to compressor



Ensure the pressure drop is less than 2 barg. 304-PDT-1206 automatically opens ESD-V1200 and suction of the compressor is pressurized



Drain the condensate from compressor casing, pipe lines and KO drum

Starting of Compressor



Set PIC1226 at 27 barg (Check the vendor manual)



Check the compressor suction pressure is about 27 barg



Make sure that start-up interlocks have been released by the control system of the compressor unit



Check the indicators in the compressor control panel



Check for any alarms and healthiness of start-up system. In case of any malfunction, or the start-up conditions are not achieved, take corrective action and ensure ‘Ready for Start’ is indicated in the panel



Check the speed control is at minimum



Ensure compressor discharge cooler fans are running and TCV1215 is on Auto mode



Ensure electrical heat tracing of compressor suction headers are activated



Select compressor suction pressure PIC1226 as control set pressure






Set the compressor discharge at 87 barg and take it on Auto control



Inform electrical substation

Following is the sequence for start of the motor in VSD mode:



Close the VSD input breaker using T/N/C switch on RCP



Keep the selector switch in ‘Normal’ Mode on VSD system



Keep the selector switch on local control station in Local Mode



See the VSD ready indication on local control station



Press the VSD Start pushbutton on the local control station



See ‘Motor Running on VSD’ indication on local control station



Check the speed, discharge pressure, lubrication and seal gas pressure, and secondary seal gas pressure



Check compressor vibration and temperature at the bearings



Check the compressor discharge pressure and performance of the compressor



Check the gas temperature at the discharge cooler outlet of first and second stages



Monitor the Air cooler outlet temperature and control at 60C by taking 304-TIC-1215 in “Auto” mode



Raise the compressor speed by selecting ‘speed increase’



Raise the speed of the compressor to 1200 rpm and check the compressor discharge pressure at PI-1232



Gradually raise the compressor discharge pressure to 87 barg, with careful monitoring of compressor for vibration, temperature at the bearing, discharge pressures, gas outlet temperature at the outlet of gas coolers



Set the discharge pressure at 87 barg and take the compressor operation on Auto Mode



Check the performance of the compressor for vibration, discharge pressure, bearing temperature, gas flow etc as detailed in the compressor vendor’s instruction manual



However, the speed of the compressor is controlled by the suction pressure of the compressor (tank pressure)

PETRO-CANADA EBLA PALMYRA B.V 00180-PCP-300-PDMan-12503-01 GGS Operating Manual Vol #1

Unit : GGS




Monitor liquid level in Suction KO Drum



Adjust the seal gas supply as specified in the Vendor’s O&M



Switch off the lube oil heater



Take electrical tracing heater on Auto Mode



Monitor the condition of the compressor and auxiliaries



Check dehydration column operating pressure



Open 304-XV-1219 at the compressor discharge and allow the gas to Dehydration Column



Control 305-C-001A Dehydration Column pressure by taking 305-PV-3024 on Manual. Set 305-PV-3024 to Auto after stable operation of dehydration column



Gradually close 304-PCV-1294 and close flaring



Take 304-PCV-1294 on Auto mode



Once the compressor performance is established, change the selector switch (SW1) in VSD to DCS position (or change the selector switch in motor LCS to DCS position)



Now the compressor control shall be taken over by compressor PLC in control room



Monitor the performance of the compressor from compressor PLC in control room



Once the compressor is loaded, the anti-surge and performance controllers will be switched from SEQUENCE to AUTO

(In case of Settle-out Pressure (46.4 barg), the seal gas supply is supplied from the HP Fuel Gas tapped from the downstream of Fuel Gas Heater (321-E-001A/B) to ensure dry heated gas is supplied to Dry Gas Seals). Refer operating instruction of vendor manual for more information. 14.2.16 

Start-up of Gas-Dehydration

Ensure the Depressurization valve 305-XV-3000 is opened due to ESD-1 trip. Reset 305-XV-3000 is reset and kept closed.



Ensure the regeneration system and dehydration system have adequate level of glycol



Establish glycol circulation by running the glycol pumps



Line-up electrical tracing. In cold weather conditions, TEG (Tri-Ethylene Glycol) is viscous and needs warming up to facilitate pouring






Ensure both reboiler and glycol surge drum are charged with glycol



Line-up one of the Glycol Circulation Pumps 305-P-003A/B. Open suction and discharge valves of the pump 305-P-003A which is selected for use. Ensure the block valves on exchangers 305-E-001, 305-E-002 and 305-E-004, and gas dehydration column (305-C-001) are lined up (normally not closed during ESD1 shutdown)



Select Local Mode by pressing 305-MHS-3121B on the local panel and start the pump 305-P-003A by pressing ‘Start’ pushbutton 305-MHS-3121A. Check for the ‘Running’ indication 305-MIXI-3121 of 305-P-003A in the DCS Panel



Establish glycol circulation by running the glycol pumps



Check the level in the glycol surge drum and maintain it if required by top-up (If there is loss of glycol during shutdown)



Maintain the pressure of Flash Drum at 3.5 barg



Line-up one of the TEG Cartridge Filters (305-F-003A/B) and the TEG Carbon Filter (305-F-002)



Line-up activated carbon filter (if degraded product is observed in glycol)



Put the level controller 305-LIC-3210 on Auto and return the rich TEG to the Still Column (305-C-002) through 305-LV-3210. TEG will then flow down to the reboiler by passing through the Pall Ring Packing in the still column



Keep the surge drum level by make-up of glycol. Check the level in reboiler and surge drum. When the reboiler is full, the surge drum level will remain constant and should be half-full with glycol. Stop filling the reboiler and close the 2” valve on glycol make-up line



Continue glycol circulation through dehydration column, glycol flash vessel, reboiler, TEG still column, Cold lean/rich glycol exchanger, Hot lean/rich glycol exchanger and Rich TEG cartridge filter by running 305-P-003A or B Glycol Circulation Pump, until Reboiler is lined up followed by gas from separator (Field Gas Compressor at a later stage) to dehydration column



Check the temperature of glycol (fuel gas firing is stopped during shutdown)



Start the gas burner assembly for the TEG Reboiler can be started either from DCS or from Local panel. Follow procedure as detailed under Section 12 above






When the Main Flame stabilization time is over and the burner start-up sequence is completed, ‘Burner On’ indication appears on local panel (305-XL-3156B) and on DCS (305-BAH-3156A)



Put 305-TIC-3109 on temperature control with 305-TV-3109 on Auto



Set a maximum temperature gradient of 60C/hour



After performing the burner start-up, progressively increase the set point for 305-TIC-3109 up to 204C



Stripping gas flow can be started manually by opening the shutdown valve 305-XV-3171 on the stripping gas line and is allowed only if the burner is ON. Once the burner is switched off, 305-XV-3171 will close automatically. After burner restart, the valve has to be re-opened manually by first resetting in the Local panel and open by operating the switch 305-XHS-3171A in DCS panel



Ensure circulation of process gas through 305-C-001 which should be established soon after the hot glycol circulation is established to avoid potential foaming problem in the column



Feeding the feed gas to the Gas Dehydration Column should be as smooth as possible



Increase the feed gas rate in steps of 25% of the maximum flow. As the process gas feeds the internal Gas/Liquid separator of the Gas Dehydration Column, the water droplets trapped will form a level at the bottom of the Contactor. When the level is sufficient, the level control valve (305-LV-3013) can be put into service in Auto with the Level Controller 305-LIC-3013



Continue routing dehydrated feed gas to HP Flare via 305-PCV-3024. Send gas samples for analysis of water content. Slowly raise the gas feed rate up to 50% of design gas feed rate



Coordinate with the Ash-Shaer Well head Personnel and maintain the choke valves so as to maintain a pressure of 50 barg at the Gas Dehydration Column. Increase the lean glycol flow to 4.5 m3/h



Maintain a constant temperature of gas feed at 50C as indicated by 305-TI-3019. Accordingly maintain the lean glycol temperature of 55C i.e., 5C above the inlet gas temperature to avoid hydrocarbon condensation



Collect samples at the outlet of the Gas Dehydration Column SC-502 to find out the dew point and the water content of the dehydrated gas






Line-up Reflux Condenser. The normal top operating temperature of the Reflux Condenser will depend on the condensation temperature of the vapours. This temperature is set at 93–98C depending upon the amount of hydrocarbon



Monitor the pressure drop across the filter. The pressure differential across the filter is readable on DCS by 305-PDT-3216/3122 for cartridge filters and 305-PDT3218 for carbon filter. When the differential pressure is 1 bar, then the ‘Standby’ filter is taken into service



Coordinate with the Well heads to open the choke valves so that the pressure of 87 bara is maintained at the top of the gas dehydration column. Maintain the injection flow rates of methanol and corrosion inhibitor as per the design flow of the multiphase gas flow



Adjust the flow and temperature of lean glycol as per the increase of the gas feed rate in the gas dehydration column. Maintain the lean TEG temperature 5C above the wet gas entering the gas dehydration column



Start the injection of antifoam and the corrosion inhibitor to various points in the TEG regeneration system



Stabilise the TEG regeneration system with temperatures and flows optimised for efficient operation of the gas dehydration system



Check two or more samples to confirm the water content of the dry gas and condensate



After the condensate and the dry gas meet the specifications, route both to the GTP trunk line



Start the TEG Incinerator manually from the field by operator by means of the push-button HS-6052B or from DCS by pressing HS-6052A, and enable sequential start-up of the incinerator. Refer Section 12 above for more details



Once the burner is in operation, the next step is to increase the combustion chamber temperature up to the minimum value for off-gas injection (pre-heating of the incinerator). A temperature ramp-up control gradually heats up the combustion chamber over a time period (to prevent thermal shock of the refractory due to full burner output when refractory is cold)


14.2.17 



Line-up of Oily Water System

Ensure to line-up blanketing gas (fuel gas) to degassing drum and Produced Water storage tank



Ensure Produced Water from Production Separator and Condensate Coalescer is lined up to Water Degassing drum (334-V-001)



Ensure water separation in Production Separator 302-V-001 and the level controller 302-LIC-1114 is lined up to 334-V-001



Take 302-LIC-1156 on Manual mode for 302-F-002A/B Coalescer to Produced water degassing drum. Set the level at 50% and take the controller on Auto



Set the level controller 334-LIC-3441 at 50% and take it on Auto. Check flow of water to 334-T-001



Line-up open drain contaminated pump to Produced Water storage tank



Ensure 334-V-001 pressure is controlled by 334-PIC-5449 and off-gas flows to flare



Observe the separation of hydrocarbon condensate at the top surface of water



Skim off HC condensate manually to Closed Drain by monitoring the interface level at 334-LI-5400



The separated water from the Produced Water tank is disposed off to tankers using Produced Water disposal pumps 334-P-001A/S

Line-up of Trunk Line 

Ensure GTP is ready to receive gas/condensate



Check the gas pressure at the exit of 305-C-001 dehydration column at 305-PIC-3024



Ensure stable operation of dehydration column



Open pressure control valve 305-PV-3009B and charge the gas up to 305-XV-3004



Reset 305-XV-3004 and charge the gas to trunk line



Monitor the pressure in trunk line



Gradually close 305-PIC-3024 and stop the flaring of gas



Set the 305-PICV-3009A/B on Auto



Set 305-PIC-3024 flaring valve to Auto


14.3






ESD-2 will close choke valve and isolate process vessels in boxed up condition.



Regeneration section- burner is put off.



GTG fuel changed over to diesel from gas.



All utilities are on line.



Ensure Instrument air pressure is above 4.5 barg.

Restart-up of GGS 1.

Check healthiness of DC-UPS.

2.

Ensure utility systems are ON and continuing operation.

3.

Production separator and dehydration sections are boxed up at operating pressure.

4.

Reset ESD-2 shut down.

5.

Line-up oily water system.

6.

Start Glycol circulation.

7.

Start regeneration section.

8.

Reset choke valve at Well head and line-up flow lines as detailed in Section 11 above.

9.

Start production separator as detailed above.

10. Start condensate section. 11. Start fuel gas system. 12. Start-up of Field Gas compressor: During the ESD-2 shutdown, when the Field Gas Compressor is tripped , the antisurge valves are opened immediately. The Compressor will be blocked in and will remain pressurized at settle out conditions. Open external seal gas will be lined up to maintain seal gas flow. Start Field Gas Compressor as detailed in Section 11 above. 13. As the Gas Dehydration Column is already in a pressurized condition Start dehydration section as detailed in Section 11 above after stabilizing the Field Gas Compressor. 14. Prepare GTP for operation. 15. Line-up gas and condensate to trunk line. 14.4


ESD3 shutdown will be associated with following: o

Production separator




o

Condensate system

o

TEG system (Closes plant outlet)

o

Inlet manifold (Closes plant inlet)

o

GTP pipeline

o

Compressor tripped (No export possible in LP mode)

The result of any of the above shutdowns is Plant Tripped condition. GTG will run on diesel. EDG will be available. All utilities will be available. Process vessels are under operating pressure. Compressor is running in closed loop (antisurge open). Restart-up of the Plant Follow the procedure for start-up of equipment as detailed in Section 11 above. 1.

Reset shutdown ESD3 for the equipment.

2.

Line-up choke valve in Well head and allow well fluid to manifold.

3.

Line-up production separator as detailed in Section 11 above.

4.

Line-up condensate to closed drain vessel as detailed in section 11 above.

5.

Flare the gas till the compressor is taken on line (LP Mode Operation).

6.

Line-up condensate to production separator by running LP operation condensate pumps (LP Mode Operation).

7.

Line-up produced water to Oily Water system.

8.

Establish glycol circulation.

9.

Start-up of Field Gas compressor: During the ESD-3 shutdown, when the Field Gas Compressor is tripped, the antisurge valves are opened immediately. The Compressor will be blocked in and will remain pressurized at settle out conditions. Open external seal gas will be lined up to maintain seal gas flow. Start Field Gas Compressor as detailed in Section 11 above.

10. Line field gas compressor (LP Mode Operation). 11. Start regenerator section and raise the temperature of glycol. 12. Admit the gas to dehydration column. 13. Control the pressure of dehydration by flaring till gas quality is achieved 14. Line-up gas and condensate to trunk line




Hazop Action No. 43 If ESD-3 trip is actuated by initiation of 305-PALL-309 (due to inadvertent action of fully opening 305-PV-3024), the Condensate injection to the trunkline should be stopped if it is a prolonged ESD-3 shutdown. Immediately after the ESD-3 trip, the Production Seperator can be operated near turndown capacity to avoid excessive flaring and condensate can still be routed to the Trunk line. For prolonged durations of ESD-3 shutdown, the condensate injection to trunkline should be stopped. . Injection of Condensate into the trunkline without dehydrated gas will accelerate corrosion in Trunkline and cause slug receipts at the GTP. Ensure TEG Incinerator is running with fuel gas and maintain the TEG circulation. Reset and start firing the TEG Regeneration Reboiler and stabilise the Gas Dehydration system before lining up condensate and dehydrated gas to the Trunkline. 14.5

BLACK START-UP OF GGS

The black start-up of GGS is similar to ESD1 shutdown. The power for start-up is made available by starting Emergency Diesel Generator with diesel. The supply is given to MCC for utilities and emergency supply panel. Assuming the EDG is supplied by the battery system and the auxiliary can be started, the procedure shown on the following page shall be adopted for start-up (Fig. 15).




Fig. 15 – Black Start-up Sequence Flowchart




Black Start-up Sequence Flowchart (Cont.)




15.0 TROUBLESHOOTING OPERATION




Production Separator Sr. No. 1

Problem

Indications

High pressure in the Production Separators (PAH). (PAHH in the separator shuts down the Separator inlet valves)

Higher pressure indication at 302-PAH-1110

2

Low pressure in the separators (PAL).

Low pressure indication as indicated by the Pressure alarm 302-PAL-1110

3

High Level in the Condensate compartment

High level indication as indicated by the High level alarm 302-LAH-1110

Diagnosis

Control Action

 More gas flow to Production Separator  Increase in the Gas Oil Ratio (GOR)  Closure of Dry gas outlet valve of Gas Dehydration Column  Sudden trip of Field Gas Compressor (LP case)  Malfunctioning of PSV at lower pressure  Passing of PSVs  Opening of PCV to Flare  Reduction in Well head pressure

 Check that the Pressure controller 302-PIC-1137 and control valves in the gas outlet line are working properly.  Check the instrument air supply tubing if the valve is remaining closed.  Check that the Control valves in the vent line to HP flare header are functioning properly.  Ensure that the SDV and the isolation valves in the inlet to the separator, from the inlet manifold are fully open.  Check the functioning of the control valves (and controller wiring) in the gas vent lines to HP flare, ensure that they are not in open condition due to failure of instrument air tubing.  Check whether the down stream ESD valve 302-XV-1151 is closed due to trip signals.  Check whether the Condensate pumps have tripped  Check the functioning of the control valves (and controller wiring) in the Condensate outlet line and ensure that they are not stuck closed due to failure of instrument air tubing.  Also check the oily water outlet line control


Sr. No. 4

00180-PCP-300-PDMan-12503-01 GGS Operating Manual Vol #1 Problem

Low Level in the Condensate compartment

Indications Low level indication as indicated by the High level alarm 302-LAL-1110

Operations Page 258 of 275 Diagnosis

Control Action   

5

6

High Interface Level in the separator.

Low Interface Level in the Separator.

High Interface level indication as indicated by the High level alarm 302-LAL-1110

 

  

valves. Check whether the drain valves in the oily water compartment are opened inadvertently. Check the functioning of the control valves (and controller wiring) in the oil outlet line and ensure that they are not stuck open. Check the flow rate of Condensate from the separator, if it is much below the design flow, increase the number of Well connections if possible Check whether the down stream SDV valves are closed due to trip signals. Check the functioning of the control valves (and controller wiring) in the oily water outlet line and ensure that they are not stuck closed due to failure of instrument air tubing. Check whether the drain valves in the separator are opened inadvertently. Check the functioning of the control valves (and controller wiring) in the oily water outlet line and ensure that they are not stuck open. In case the water cut of the oil is very low, the separators can be operated as 2 phase separators.




Glycol Losses Sr. No. 1

Problem

Indications

Glycol loss from Dehydration Column due to inadequate cooling

 Frequent top up of lean Glycol from TEG tank  305-LV-3210 MV gradually increasing Excessive gas velocity due to increased gas feed rate Excessive collection of Glycol in the Glycol Vent Gas K.O. drum (305-V-003) Differential pressure 305-PDI-3007 is on the higher side

2

Glycol Loss due to Entrainment losses

3

Vaporization Losses from Glycol Reflux Condenser

4

Glycol loss due to foaming in 305-C-001

5

Glycol loss from the Still Column (305-C-002)

 Excessive gas velocity due to increased gas feed rate  Differential pressure

Diagnosis

Control Action

Analyse the Dry gas sample for TEG. typical value is 0.45– 0.78 US gal/MMSCF

 Reduce the Inlet gas temperature 305-TI-3019 to 50°C if it above 50°C.  Reduce the lean Glycol temperature 305-TI-3076 entering 305-C-001 within 3°C of the inlet gas temperature.

Analyse the Dry gas sample for TEG. typical value is 0.45–0.78 US gal/MMSCF  The Glycol overhead temperature 305-TI-3103 is above 100°C  305-TCV-3102 MV gradually increasing  Analyse rich TEG from 305-C-001 for Hydrocarbon, salt or amine (corrosion inhibitor)  Abnormal increase in the condensate level of Glycol Flash drum Give samples to check whether free water is entering 305-C-001 and over loading the Regenerator by analysing water content of feed gas

 

Decrease gas Flow rate Increase the gas pressure in 305-C-001

 305-TIC-3102 should be maintained at 95°C

 Remove the source of contamination, if it is badly contaminated recharge the system with new Glycol.  Add Antifoam but be careful not to add too much  Decrease gas Flow rate  Clean or replace the packing if fouled

Still

Column


Sr. No.


6

Mechanical leaks

7

Glycol loss from the Flash drum

Indications 305-PDI-3104 is on the higher side Lot of Glycol dripping from the Glycol pump (305-P-003A) glands Abnormal opening of the Condensate tank LCV 305-LCV-3206 control valve

 Frequent top up of lean Glycol from TEG tank  The inlet to Gas Dehydration Column is around 7ºC during the HP cases. Low Pressure in Gas Dehydration Column 1 Low Pressure in the  Low pressure Gas Dehydration alarm from 305Column PAL-3012  High flow alarm in the Flare header 331-FAH-5126 8

Glycol loss during winter periods


Control Action

Observe continuously and confirm leaks are from the glands of the Glycol pumps.  Take a sample from Hydrocarbon condensate outlet line and analyse for Glycol  When there is more Glycol carryover, 305-LCV-3210 will slowly move to closed position.  Analyse the Dry gas sample for TEG. typical value is 0.45 - 0.78 US gal/MMSCF

Regular Preventive maintenance for the pumps

 Check whether the start-up depressurisation valve 305-PV-3024 is inadvertently opened  Field Gas Compressor 304-K-001A/B has tripped  Controller 305-PIC-3009 will close

 Immediately close 305-PV-3024 and improve the pressure  Identify the trip reason and start the Field Gas Compressor

 Lower the Glycol weir if Glycol carryover is confirmed. It should be set at a minimum of 75 mm below that of the condensate.

 During winter case operation put exchanger 305-E-001 on line  Ensure that electrical tracing system on Gas Dehydration Column bottom, wet condensate outlet line and chimney tray portion of the Gas Dehydration column


Sr. No.


Indications


Control Action

305-PV-3009A/B High Water Content in the Treated Gas Outlet Sr. No. 1

Problem

Indications

Diagnosis

Glycol Pump Stroking but not pumping

 Glycol Pumps are stroking but not pumping  The dry gas outlet 305-AI-3022 giving high level alarms The dry gas outlet 305-AI-3022 giving high level alarms

 Pump running indication is there but Glycol flow transmitter 305-FI-3113 flow is hunting

 Check the valves to see if they are seating properly.

 Pump running indication is there but Glycol flow transmitter 305-FI-3113 flow is hunting  Glycol Inventory comes down gradually from the Glycol system less  Verify the Reboiler temperature with a test thermometer and check whether correct temperature is maintained in the Reboiler  Check Glycol-Glycol heat exchanger for leakage of wet Glycol into dry Glycol by

 Clean the suction Strainer of Glycol pumps

2

Glycol Pump suction strainer blocked

3

Excessive leakage from Glycol Pump Plunger glands Insufficient Concentration of Glycol

4

Excessive Glycol leakage from the Glycol pump area Circulation rate is adequate but the Dry gas outlet showing higher moisture content

Control Action

 Attend Glycol pump leaks with the help of Maintenance crew  Keep Reboiler temperature at the maximum allowable temperature.  Rectify the leak of the Glycol-Glycol exchanger  Maintain the correct stripping rate


Sr. No.


Indications

5

Poor Glycol distribution

Pressure drop across the Contactor packing is very minimal

6

Operating conditions different from design conditions

Lower Contactor pressure, higher feed gas temperature and lower Glycol circulation rate than the design value

Operations Page 262 of 275 Diagnosis analysing dry Glycol sample  Check stripping gas rate The dry gas outlet analyser showing high value even though correct Glycol circulation rate and correct concentration is maintained Adjust the process variable to find improvement in the dry gas outlet

Control Action

Check alignment of distributor and ensure there are no blockages

   

Increase the Contactor pressure Reduce feed gas temperature Increase the Glycol circulation rate Check the lean Glycol temperature feed to the Contactor and reduce if necessary near feed gas temperature between 3 to 6° C

II UTILITIES AND OFF SITES Sr. Problem No. Instrument Air Low Header IA 1 Pressure

Indications 325-PALL-4733 sounds alarm

Diagnosis

Control Action

 Header pressure is lowering. Header pressure 325-PI-4733 indicates low pressure  More consumption of nitrogen and 325-XV-4725 is full open  Air Compressor is tripped and

 Check325-PV-4660 got struck open and more plant air consumed. Take the control valve manually and control the pressure  Reset XV-4725 and close the valve  Check at the field and start the standby compressor


Sr. No.

2


Dew Point less than -35degC at 7.5 barg

Nitrogen O2 more than 2% in 1 nitrogen product

Indications


Control Action

the standby has not come on line  Running Compressor tripped and standby is not getting started

 Close N2 consumption valves and Plant air consumption  Check electrical fault.  Restart after attending the fault as per PTW system  Check electrical fault (MCC)  Check the function of regeneration heater  Check the operation of three way valve  Change the molecular sieve

Instrument air outlet showing higher moisture content

 Check Regeneration temperature/Heater  Check passing of 3 way valve  Check regeneration cycle  Higher pressure drop/Channelling due to deterioration of molecular sieve

O2 analyser 324-AI-4819 indication

 High pressure drop due to fouling of membrane  Faulty analyser

 Cleaning of membrane  Calibrate analyser



16.0 SHUTDOWN



16.1



PLANNED SHUTDOWN

Initial Status 

Condensate and gas system is running and operating conditions of all equipment are within limits.



Productions from all seven gas fields of Ash-Shaer are on and running at normal rates.



Condensate production is on at design production rate and specifications are within limits.



Gas separated in the Production Separator is sent to Gas Dehydration Column directly or though Field Gas Compressor during the LP Stage.



The dry gas from the Gas Dehydration column is meeting the specifications and the TEG Regeneration system is working normally.



Water separated in the Production Separator is sent to Produced water tanks.



All chemical injection systems are working normal and the chemicals are injected at specified rates.



The gas and the condensate are mixed together and sent to GTP through the trunk line.

Unit Shutdown There are many local conditions within GGS that will shutdown particular process equipment or whole of the Plant Equipment in GGS due to Process or Utility outages as defined on the Cause & Effect diagrams Doc No: 250-EPR-CNE-05001 (High or low levels, pressures, temperatures, etc,.). In some cases like suction filter choking or pump problem, the absence of spare unit will lead to shutdown. Normal Shutdown of Production Seperator As the shutdown is a planned one, the Operator will plan in advance the steps involved in the normal Shutdown of the Production Seperator. 

Inform the GTP Unit, Wellheads, Glycol Dehydration Unit and the TEG Dehydration unit about the shutdown of the Production Seperator.



Reduce the capacities of the Producing wells by closing the Choke valves slowly till the turndown capacity.



When the turndown capacity is reached, the System can be depressurised in case of longer shutdown or kept at the same pressure as the case may be.






Hazop Action No. 27 If the Plant is taken for Annual/Long shutdowns, it is required to drain all the Produced water lines to prevent ice formation and corrosion of pipeline.. In case of failure to switch on heat tracing, will lead to blocking of Produced water lines and thereby increases water level in Production Seperator. This will lead to water carryover in condensate and corrosion in the Trunkline. Hence a regular schedule should be prepared to do regular monitoring and preventive maintenance of the Heat Tracing.



Hazop Action No. 67 Handling and disposal of Contaminated filter Catridges/Coalescer elements should be done in safe manner. As these filters contain hazardous sulphur and nitrogen compounds this should be collected and disposed in designated storage areas. Proper PPEs as given in Section 2.3 and Precautions should be given to all personnel involved in handling the contaminated equipments to waste storage area.



Hazop Action No. 31 When releasing Condensate/Produced Water Storage tanks, Condensate pumps/Filters, proper safety precautions are to be taken as per PTW Procedures and for vessel entry by

Personnel. Check for Oxygen/Toxic HC

components. The vessels are damped from a water source to avoid pyrophoric iron burning. Naturally Occurring Radioactive Material (NORM) and Low Specific Activity (LSA) Scale can appear during the drilling and process phases of Oil and Gas exploration and production and tend to deposit along with other scale. Low Specific Activity scale (LSA) which are found adhering to pipe and equipment internals produce potential radiation illness mainly due to Radium-226 produced from the decay of naturally occurring Uranium-238. Hence Radioactive Detection and PPEs for protection against potential radiation illness should be used. The waste removed from Condensate storage/Produced water storage tanks/catridge filter should be disposed off at locations specifically marked/designated as Waste holdup/storage area. The Waste disposal area shall be clearly fenced, marked and identified with safety tags/boards indicating warnings/dangers due to radioactive substances.




Normal Shutdown of Gas Dehydration/TEG Regeneration System As the normal shutdown has been scheduled and prepared, it should not present the operator any undue problem to successfully perform it and the suggested guidelines are followed: o

Stop the gas to the Gas dehydration Column (305-C-001).

o

Stop the burner of the TEG Reboiler.

o

Stop the Glycol pump 305-P-003A/B, when the temperature in the Reboiler fall under 190°C.

o

Stop the Vent gas blower 305-K-002A/B.

If the shutdown period is of longer duration, then the glycol contained in the Gas Dehydration Column should be collected in the bottom head and evacuated under level control to the flash drum and then to the surge drum where the glycol will be built-up. The glycol regeneration package and the gas dehydration column are now in a standby condition, levels and pressures are still maintained close to the operating conditions and if required, the unit start-up can be carried out immediately from this condition. If the standby period will be of longer duration, then it is necessary to proceed as follows: o

Isolate gas dehydration column outlets.

o

Isolate flash drum condensate outlet and glycol outlet.

o

Close ball valves at glycol pump discharges.

o

Leave the gas or vapour outlet of process vessels open.

If the shutdown involves internal repair work or maintenance on whole or part of the package, it will then become necessary to fully isolate the equipment from the rest of the system to drain and depressurize it. Hazop Action No. 522: Any leak in the Dry gas/Lean TEG Exchanger will lead to glycol carryover along with dehydrated gas. This will result drop in Surge drum level and initiates an Low level alarm (305-LAL-3115) due to loss of glycol. As there is no isolation bypass available for the shell & tube sides, unit has to be shutdown if leak develops on either side. As there is a potential leakage due to corrosion of the 305-E-004 tube bundles, proper monitoring has to be done which will reduce the 305-E-004 tube bundle leakages. 

Proper monitoring of corrosion coupon 305-CC-3080 on the Gas Dehydration Column overhead vapour line. If corrosion rate is more increase the corrosion inhibitor injection rate at the outlet of TEG carbon filter.






A spare tube bundle availability helps in quick start-up of the Gas Dehydration plant in case of any leak



Provide isolation and bypass valves for both shell and tube side.

Note: During winter period (when the ambient temperature falls below –15C), drain the column bottom and condensate outlet pipeline to column bottom, in order to avoid liquid freezing. In case of longer shutdown during winter, glycol also need to be drained for non- traced lines in order to avoid freezing due to the lower ambient temperatures (–15°C) and TEG freezing temperature of –7°C. Normal Shutdown of Field Gas Compressor As the Field Gas Compressor boosts the pressure to 87 barg before the introduction to Gas Dehydration column the feed rate reduction has to be done in steps upto the turndown feed rate. 

Inform the GTP Unit, Wellheads, Glycol Dehydration Unit and the TEG Dehydration unit about shutdown of the Field Gas Compressor.



Reduce the capacities of the Producing wells by closing the Choke valves slowly till the turndown capacity.



The Antisurge valves open automatically when the flow rates are reduced.



After the turndown of the Gas Dehydration column, the Field gas Compressor can be tripped or can be kept running in recycle mode if it is a shorter shutdown duration.

16.2

EMERGENCY SHUTDOWN

ESD systems will function to isolate inventory entering or exiting plant facilities, to remove heat input to heaters and reboilers and stop associated rotating equipment; this is necessary to ensure safe operation. A separate ESD system is provided at each location i.e. at Well heads, GGS and GTP. While each system operates independently, certain emergency situations at one site will activate a shutdown at other location also. The emergency shutdown systems at GGS will operate on three hierarchical levels. A shutdown at one level will typically cascade to initiate shutdowns at the next level. The ESD levels adopted for the facilities are as follows: o

ESD Level-1 shutdown: ESD Level-1 shutdown will open all the depressurizing valves at the same time.

o

ESD

Level-2

shutdown:

ESD

Level-2

shutdown

will

depressurization, allowing for operator action if required.

enable




ESD Level-3 shutdown: ESD Level-3 shutdowns are used only to isolate or shutdown systems. Individual unit/equipment may be depressurized if necessary.

16.2.1

ESD Level-1 Shutdown

ESD Level-1 represents the highest level of emergency that may occur at the facility. A confirmed fire at the GGS or any Plant emergency justifies manual initiation. ESD Level-1 will shutdown and depressurize the process facilities. ESD level-1 is initiated by the following: o

Manually by an authorised Operator in the control room or gate house (GGS and GTP)

o

Automatically via the F&G system on 10% LEL confirmed gas detection in the HVAC inlet of the control room and substation of GGS.

o

Confirmed fire at the GGS will initiate ESD Level-1 at GGS due to extended periods of unattended operation.

o

Confirmed high level gas detection (20% LEL) at the utilities area of GGS. This represents the highest level ESD at the installations as these will trip the Emergency Generator.

ESD Level-1 Actions 

Shutdown the Main Power Generators but maintains operation of EDG to maintain essential utilities. EDG shall not start in case of 10% LEL confirmed gas detection at HVAC inlet and 20% LEL in Utility area. Should all power be lost during the emergency, Power for control and safety systems will be maintained by the UPS battery systems.



Close the GGS Well head chokes, GGS remains live with Compressors on recycle for ESD level-1 at GTP



Opens all EDP (Emergency Depressurizing) valves after a time delay of 1 minute to allow all XVs to close on ESD Level-1 at GGS. The system will enable the CR/CCR Operators to over-ride the blowdown signal once initiated. This will be achieved by normalizing the ESD Level-1 initiator and pressing the ESD Level-1 Reset button.



ESD Level-1 at the GTP will automatically initiate an ESD Level-2 shutdown at the GGS via the fibre-optic link which will ramp close choke valves at Well head. ESD Level-1 or ESD Level-2 at GGS will result in an alarm at GTP.




16.2.2 ESD Level-2: Process Shutdown ESD Level-2 is activated in the event of a significant process abnormality at the facilities; it indicates a potential loss of containment, fire (GTP only) or impairment of the ability to control the plant in a safe manner. This may be as a result of gas detection in open areas (20% LEL); loss of control air, fuel gas or power; High-High liquid Levels in the Flare knock out drum or abnormally Low-Low pressure in pipeline systems. On ESD Level 2, Operation of the facility shall be stopped by closing dedicated XVs and tripping all processing equipment. Essential utilities such as power generation will be kept operating on ESD Level 2 by switching the Main generators to Diesel operation at the GGS or running the generators on buy-back gas at the GTP except in case of instrument air Low-Low pressure where GTGs will be shutting down. ESD LEVEL-2 is initiated by the following: o

Automatically, by cascade from ESD Level-1 at GGS & GTP.

o

Manually, by an authorized operator either in the control room or at selected locations in the plant at GGS & GTP.

o

Automatically on Low Low instrument air pressure at GGS & GTP.

o

Automatically, on failure of main power generation at GGS & GTP.

o

Automatically on High High flare drum level at GGS & GTP.

o

AT GGS Automatically, on fuel gas KO drum Low Low pressure. All other fuel gas ESD level-3 (like High High level and Low Low temperature) will switch the main power generator to diesel operation. This takes 40-60 seconds but is assumed not to be possible on fuel gas Low Low pressure. After successful automatic change over of GTP to diesel operation, the ESD Level-2 shut down can be RESET after over riding Low Low fuel gas KOD pressure.

o

AT GTP Automatically, on the fuel gas KOD pressure High High pressure, Low Low pressure, High High liquid level, Low Low temperature will cause ESD Level- 2.

o

Automatically on FG ESD Level-3 at the GTP (cascades to loss of Power).

o

Automatically at GGS on confirmed Low Low pressure in the gathering system or at GGS and GTP on Low-low pressure in the GGS to GTP pipeline.

o

Automatically on sales gas compressor discharge metering pipeline Low Low pressure.

o

Automatically via the F&G system on: o

20% LEL confirmed gas detection in the process area at GGS & GTP.

o

Confirmed fire detection in process areas, GTP only




Confirmed 20% LEL gas in the generator area will trip or inhibit start of the Main or Emergency Generators (for GGS & GTP)

ESD Level-2 Actions 

Initiate all ESD Level-3 trips.



Close the choke valve at gas Well heads at GGS



Switch Main Power Generation to diesel and start the Emergency Power Generator at GGS



Maintain fuel gas supply to the main generators by opening the buy-back fuel gas XV at GTP.



Trip the main power generators only on low Instrument air pressure (loss of control)



Start the Emergency Generator (except in case of 20% LEL gas in generator area).



Enable blowdown of the facility. Blowdown may then be initiated manually.



On Confirmed fire at the GTP or low pressure in the Firewater Ring Main, start Fire Water Pumps (via the F&G system)



On GGS ESD Level 2 initiated by pipeline Low Low pressure, isolate 701-XV-3150 on the incoming trunk line at GTP to isolate the pipeline at both ends.



ESD Level 2 at either the GGS or the GTP will result in an alarm at the other site.

16.2.3 ESD LEVEL-3: Unit/Equipment Shutdown ESD Level-3 shutdowns are non-emergency process abnormalities affecting only one equipment or unit. ESD Level-3 trips are provided primarily for equipment protection where there may be safety and/or environmental consequences if equipment failure is not prevented. typical trips include shutdown of a compressor on high-high discharge temperature, and shutdown on a dehydration unit on highhigh level in the inlet separator. The extent of the trip depends on the ability of the remainder of the unit to continue without the affected item. ESD-3 shutdown is initiated by the following: o

Automatically, by specified abnormal process conditions (refer to the Cause & Effect Diagrams for details)




Manually, via an ESD pushbutton at the unit (local or on control panel)

o

ESD-3 actions are typically:

o

Shut down and isolate a single equipment item or train.

o

Shutdown and isolate a complete process unit.

o

On Low-Low pressure of nitrogen, trip, isolate and depressurize the Field gas Compressors (GGS) or Sales Gas Compressors (GTP).

The shutdown of a unit affected by an ESD-3 shutdown of another unit may not occur automatically in all cases, some cascaded shutdowns may be permitted to give the operators time to reset a unit upset condition before a plant wide trip is initiated. An ESD-3 typically involves isolating the inlet and outlet hydrocarbon streams to a unit via dedicated XVs and stopping input of heat energy. Emergency shutdown isolation for non-hydrocarbon services shall be designed on a case by case basis. For pumped systems, a Low Low level trip will be provided on the suction vessel in order to protect the pump from damage due to dry-running, regardless of the system volume of fluid contained. The trip will stop/inhibit the pump (s) and close XVs in the suction and/or discharge lines where provided. On mechanical seal failure the operating pump should trip and Auto start stand-by pump (case by case basis). Pumps which are essential for the continuous operation of the plant will have standby and will be provided with Auto-start facility for the standby pump. Lowlow discharge pressure trips operating pump and allow Auto start of stand-by pump if Low Low pressure persists, it will trip both pumps. Low-Low nitrogen pressure at compressors (nitrogen typically provides a final barrier against gas leaks from the seals) will shutdown and EDP the compressor concerned. Where possible, the remainder of the plant will be kept live and/or operating in recycle mode. ESD Level-3 Stoppages at GGS There are several major system ESD Level-3 shutdowns at the GGS which will cause loss of gas export from the plant due to isolating of the inlet or outlet XVs or which trip the Field Gas Compressors. These are: o

Production Separator/Condensate System ESD LEVEL-3 (closes plant inlet)



o

TEG System ESD Level 3 (Closes Plant outlet)

o

Inlet manifold PHH (Closes plant inlet)

o

GTP pipeline PHH (Closes plant outlet)

o

Compressors tripped (No export possible in LP Mode)


Under these trips the following actions will be initiated: o

Main generators will transfer to diesel operation to be available for plant restart

o

Emergency generator will start to be ready for failures on transfer of the main generators

o

Well heads will be isolated by closing the chokes to avoid excessive flaring at the GGS.

o

The remainder of the plant will remain live and, where possible, the Field Gas compressors will continue to run on recycle mode via the anti-surge recycle loop.

Emergency Shutdown In the event of a complete unit shutdown, the sequence shall be as follows: o

Stop the gas flow through the Contactor 305-C-001

o

Stop the Burner. See Burner stop and sequence from the Vendor manual.

o

Stop the Glycol circulation pump 305-P-003A/B

o

Close all the shutdown valves; 305-XV-3212, 305-XV-3213, 305-XV-3001, 305-XV-3002, 305-XV-3003 and 305-XV-3004

o

Stop the Vent gas blower 305-K-002A/B

o

Open the blowdown valve 305-XV-3000 for depressurization to flare

Planned Shutdown 

Inform GTP personnel that GGS is going for a planned shutdown.



Adjust Choke valve in the oil production Well heads for a reduced rate of production and stop production from Wells one by one. Always gradually, bring down the production rates.



The field operator should check the levels in Production Separator, Gas Dehydration, TEG Regeneration and Condensate system.






At the reduced rate of production, ensure that the Condensate and Gas Dehydration systems equipment are operating in normal conditions, without any abnormalities.



Reduce the chemical injection to required rates in the Well heads and the Gas Dehydration/TEG Regeneration system. Further reduce the flow rate from the production Well heads to Production separator. Monitor the operation of the equipment in Condensate system.



The control room operator and field operator should co-ordinate effectively for the shut down of the plant.



Ensure that all the equipment is running, without any abnormalities, in reduced load condition. Further caution the GTP unit that the Gas/Condensate export will be stopped.



Stop the Chemical injection.



Shut down the oil producing Wells and close their respective choke valves.



Levels in the Production Separator and Condensate system will reduce. Reduce the level set points in Separators to the minimum acceptable levels such that enough free volume will be available during restart.



If required the pressure in the pipelines can be reduced further by slowly reducing the Production Separator pressure controller set point to 24 barg. This may cause the manifold ESDVs to close by the action of PSLL setting. Now the water/oil outlet lines from the separators are isolated.



For the Gas Dehydration system, refer Shutdown of Gas Dehydration system.

16.3

DRAINING PHILOSOPHY/RECOVERY FOR START-UP

The drainage system shall be designed to allow disposal of liquid inventory in a safe and environmentally acceptable manner. Drain systems shall be designed to ensure proper handling of any contaminants that may accidentally enter the system due to spillages or in advertent operations. The drain systems that may be provided at each plant are described below: Closed Drain (CD) A Closed drain system is provided to receive hydrocarbon liquids drained from process equipment prior to maintenance. Aqueous and hydrocarbon draining will be segregated. Equipment drainings that are predominantly water will be run down to Accidentally Oily Sewer/Open drain.




The Closed drain system will comprise a hard piped collection system with drain liquids flowing by gravity to a Closed Drain Drum (Located in a Sump). Also the Closed Drain drum is equipped with Electric heater to prevent icing/freezing. The drum is designed to receive the largest single inventory to be drained. Collected liquids will be pumped away with vapour in-breathing and out-breathing will be via a vent line to the flare system. The system design pressure will be set to match flare system. Liquids collected in the Closed Drain Drum will be pumped to Flare KOD in GGS. Hazop Action No. 360 The Closed system will be positively isolated from the process by closing of valves at equipment during normal operation. The draining to Closed Drain drum is done one equipment at a time to have a better control and draining so as to avoid overflow of Closed Drain Drum. At any time, two equipments will not be drained simultaneously. Draining of more than one equipment may lead to liquid build-up in Closed drain drum and liquid carryover to the Flare header which is undesirable. Hence proper coordination should be planned in advance regarding the draining of liquids from equipments during shutdown. Where equipment is connected to a Closed Drain System for draining prior to Maintenance or inspection positive isolation for e.g. a spectacle blind will be provided between the equipment and the drain. The drain will be positively isolated during normal operation and the draining will be performed after shutdown and depressurization of the equipment item. The only exception is draining of Oil pad from Produced Water storage Tank (334-T-001) and contaminated water storage tank (834-T-001) at GTP. Pressurized draining will be allowed during start-up like draining of Compressor casing drains. For drains which need to be used under normal operation like level instruments/bridle drains, the spectacle blind is left in open position and operators will turn it closed as and when required for equipment isolation. Consequently intermittent drainage required during normal operation will be returned to the process. Chemical Sewer Injection chemicals such as methanol etc are present at the EBLA Gas Project facilities in sufficient quantities to justify a dedicated chemical sewer. Storage facilities will be bunded or kerbed to ensure containment of spills; spills inside these areas will be collected in local pit and pumped out to drums. Chemical spills outside containment areas will be dealt with by use of an appropriate absorbent. TEG Drain System TEG drain system is provided for collecting drain from TEG Regeneration system. The system is comprised of a hard piped collection system with drain liquid flowing by gravity to a TEG sump drum. The drum will be sized for hold-up of the entire TEG inventory. Vapour out breathing will be through vent line to flare and pressure relief will be discharged to flare. The system design pressure will be set to match the Flare system. The TEG drain system will be positively isolated from the process during normal operation (only exception is drain connection for level instrument/bridle). Draining will only be performed after shutdown, depressurization and cooling of the




equipment item. The drain system will be positively isolated from the equipment before the item is returned to service. If the shutdown period is for longer duration, the glycol is collected in the Chimney tray of Glycol contactor and transferred under level control to Flash drum and then to Surge drum. If the shutdown involves repair work or Maintenance in the Regeneration package, then it becomes necessary to isolate the equipment from the rest of the system, drain and depressurize it. Hazop Action No. 961 When the Gas Dehydration Plant is shutdown for longer periods during winter, then TEG needs to be cooled sufficiently and drained to TEG Drain vessel. 

Draining Hot TEG above 60C will damage drain piping and also hazardous for handling.



Hence circulate TEG by the Glycol circulation pumps through Glycol Cooler. Bring down the temperature below 60C and transfer to storage.



Drain liquid from vessels to TEG Drain drum and pump to storage.

GGS Operating Manual Vol 1

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