76530132 Process Design Manual Lurgi

Process Design Manual Process Engineering Design Basis (Rev 0, October 2000)

PROCESS DESIGN MANUAL FOR PROCESS ENGINEERING DESIGN BASIS

Doc. No. OTV –00043, Page 1 of 25


Responsible Issuer:

Head of Department – Process Engineering Table of Contents

Section 1.0 P&ID Engineering and Philosophy 2.0 Utility Battery Limit and Utility Header & Block Valves 3.0 Connection for Instruments 4.0 Equipment Sparing Philosophy 5.0 Equipment Duty Margin 6.0 Pressure Relief Philosophy 7.0 Insulation and Tracing Philosophy 8.0 Process Block Valves Philosophy 9.0 Utility Station Location Philosophy 10.0

Isolation Blinds / Spading Philosophy

11.0

Tank Fittings and Accessories Philosophy

12.0

Equipment Design Philosophy

13.0

Minimum Liquid Surge Requirement

14.0

Utility Conditions

15.0

Noise Control

16.0

Aromatics Handling

17.0

Corrosion Allowance

18.0

IBR requirements

Anoop Sharma, Approval: Name, Date, Signature

Copying of this document, and giving it to others and the use or communication of the contents thereof, are forbidden without express authority by Lurgi.



Dated : December 04, 2000

Foreword We are pleased to note that Process Engineering Department is releasing the “Process Engineering Design Basis” for use by its engineers. In the past, it was seen that the engineers had to resort to repetitive use of uncompiled information required by them in their day to day work. The need was therefore felt to compile all the design guidelines/data in one place. The exercise carried out by the process engineers was therefore a fruitful one in the generation of this manual. We are sure the manual will serve as a useful tool for the process engineers in their day to day work.

Dr. Sudhir Kapoor Managing Director and CEO

Onkar Gupta Director Operations



1.0

P&ID Engineering and Philosophies

1.1

General Pressure drop and velocity criteria for the sizing of lines are outlined below. For revamped units higher line velocities may be considered for existing lines.

1.2

Standard Line Sizes The following non-standard line sizes will not be used unless approved by customer. ¼”, 2 ½”, 3 ½”, 5”, 7”, 9”.

1.3

Minimum Line Sizes The following guidelines should be applied: 2” 2” 1½” ¾” ½” 1½” 4”

1.4

NB NB NB NB NB NB NB

Minimum nozzle size for vessels, tanks and heat exchangers. Minimum process (hydrocarbon) line size. Minimum utility line size. Minimum bridle drain or pump casing vent / drain. Minimum chemical injection. Tubing size to be 10 mm. Minimum on pipe rack. Minimum for underground lines (wrapped and coated)

Roughness Coefficient The following roughness coefficients are to be used, unless stated otherwise: Material

1.5

Roughness (Inches)

Carbon steel pipe

0.0018

Flare/vent headers (heavily corroded)

0.018

Stainless steel pipe

0.001

Glass reinforced epoxy pipe

0.0001

Pressure Drop Calculations Design margins for two phase flow pressure drop calculations normally are 50% of the pressure drop calculated at normal flow to allow for inherent inaccuracy in the calculation methodology, manufacturing tolerances, deterioration of the new pipe with scale, etc. It is important not to oversize pipe with vertical upward two-phase flow. The flow regime shall be calculated for design, normal, and turndown. Every effort shall be made to avoid slug flow regime.



1.6

Pressure Drop Calculations for Vapour and Liquids These margins are based on experience and range from 0% to 20% plus on the pressure drop at normal flow, depending on the configuration of the system being designed. For most systems, 20 % pressure drop margin is applied. However for very low pressure systems, margins are individually assessed, for example in a tank to vent pipework.

1.7

Equivalent Lengths Pipe fitting, contractions and enlargements are taken into account by utilising “equivalent lengths” as per normal engineering practices.

1.8

Limiting Velocities and Pressure Drops ft/s

m/s

Press. Drop, bar/100 m

4 5.2 10 4 7 4 to 6 10 API-RP14E

1.22 1.6 3.05 1.22 2.14 1.22 to 1.83 3.05 API-RP14E

0.1 to 0.06 0.05 to 0.22 0.2 to 0.5 0.06 to 0.1 -

250 200 150 100

75 60 45 30

20 to 40 40 to 80

6 to 12 12 to 25

50 √

15 √

Liquids Pump Suction- boiling Pump Suction- sub-cooled Pump Discharge Sidestream Draw-off Amine, Carbonate, Sour Water Sodium Hydroxide Salt Water Erosion Limits Gases General Less than 1.03 bara Upto 6.9 bara Upto 69 bara Over 69 bara Compressor Suction - Reciprocating - Centrifugal

0.1 to 0.06 0.06 to 0.13 0.13 to 0.5 0.2% of Pressure

0.02 to 0.6**

Steam General High Velocity Flow (pressure let down)

0.1 0.1

d *

0.9 Mach * d is in inches ** Depends if short or long line and steam pressure level

d *

0.9 Mach

1.9

Net positive Suction Head (NPSH)

1.10

A margin of at least 0.9 m between calculated NPSH and available NPSH has to be applied. For positive displacement pumps, effect of acceleration head on NPSH will be taken into account. Differential Head Calculations



Besides discharge piping loss, other losses taken into account are: Orifice pressure drops

:

0.2 kg/cm2 assumed

Equipment drops; e.g. heat exchangers

:

fouled pressure drop

Control valve pressure drop (for pump head calculations)

:

The greater of the following : - 50 – 60% of the total frictional loss excluding the control valve - 0.7 kg/cm2 - 15% of the pump differential head For valves installed in extremely long or high pressure drop lines, the percentage drop cross the valve may be somewhat lower, but at least 15% up to 25%, where possible, of the system friction drop should be taken.

Head Loss

1.11

:

Based on low liquid level in suction vessel and high liquid level in the discharge vessel or discharge nozzle elevation of discharge vessel, which ever is higher.

Boiler Feed Water Pumps BFW pumps will meet the requirements of ASME code section 1; i.e. be capable of supplying water to boiler at a pressure of 3% higher than the highest setting of any safety valve on the boiler.

1.12

Vents, Drains and Steam out/Purge connections for Equipment: a. Process Vessels Process vessels (tower and drums) shall have vents, drains and steam-out or purge connections as shown below: Equipment Volume m³

Vent Size in

Drain Size in

Steam out or Purge Size, in

Upto 17 (600 ft3)

2

2

2

17 to 141.5 (600 – 5000 ft3)

2

3

2

141.5 to 283 (5000 – 10,000 ft3)

3

4

3

283 to 708 (10,000 – 25,000 ft3)

4

4

3

over 708 (over 25,000 ft3) * To be located on opposite sides

6

6

Two 3 *

b. Exchangers (Shell and tube)



Provide 1” NB x 300 # (min.) flanged vents and drains at high and low points on Heat Exchangers. All vents and drains are to be valved and blanked off. Exchangers in total condensing service require a 2” vent connection at the opposite end of the shell inlet. Sizes of Multi purpose connections and pressure gauge connections on exchanger nozzle shall be 1” NB x 300 # (min.) for below 12 “ nozzles and 2” NB x 300 # (min) for 12” and over nozzles. Multi purpose nozzles can be used for thermometer connections if required. 1.13

1.14

Piping Pipe Size, in

Vent Size, in

Drain Size, in

4 and below

¾

¾

6 to 10

¾

1

12 and over

1

1½

Air Coolers On Air Coolers one 2” vent shall be placed at the highest point on the inlet header and one 2” drain at the lowest point in the outlet header. The exact locations of these vents and drains are dependent on the actual cooler design. Connections are to be valved and blanked off.

1.15

Pump Casings For non-volatile services, casing vents and pumps drains shall be piped into a sewer or closed drain system. For volatile services, casing vents and drains are to be piped to the relief header and sewers.

1.16

Additional Notes 1.

2. 3. 4. 5. 6.

Valved and blanked off vent and drain connection shall be furnished on all equipment that is not self-venting or self-draining. Connection shall be located on equipment, if practical, but may be located on connected piping when there are no valves or blocks between the vent or drain connections and the equipment. Hydrostatic vents and drains for piping are to be provided and will not be shown on P&ID. When soda ash neutralisation is required in shell and tube exchangers, standardise on 2” flange connection. At relief valves, a ¾” valve blanked off bleed shall be shown upstream of safety valve. Vents from vessels that may chill and freeze during depressurising shall have double block valves separated by at least 900 mm. Steam out connections shall be located at minimum distance above the bottom head seam of vertical vessels and the side or head of horizontal drums.



7.

Steam-out connections shall be located at minimum distance above the bottom head seam of vertical vessels and the side or head of horizontal drums. Blanked off vents shall be located on the top head of towers and vertical vessels. They shall be located on the top of horizontal drums at the same end as the drain and the end opposite from the steam out or purge connection. A vessel drain shall be located in the bottom outlet line when the outlet line is located where it can be used to drain the vessel. Consider adding downstream orifice for vessel drains under pressure to limit drain velocity. Minimum size vents for vessels having only one personnel access way shall be 4” for horizontal vessels and 2” for vertical vessels. Minimum manhole size shall be 20” internal diameter. Large size manholes will be specified if required to accommodate internals. For underground vessels the minimum manhole size is 30” internal diameter. In trayed columns, manholes will be provided above top tray, below the bottom tray, at the feed tray, at any other tray as identified on process data sheets. Maximum spacing of manholes does not exceed 10 m. The minimum spacing of trays between manholes shall be 760 mm. In horizontal vessels, equal or longer than 6 m, if an internal baffle is installed, two manholes will be required, one manhole in every compartment.

8. 9. 10. 11. 12. 13. 14.

2.0 2.1

Unit Battery Limit and Utility Header & Block Valve General For new units and / or new storage, two block valves, blind and ¾” bleed or vent will be provided at battery limits. When a second valve is located within the process unit, only one block valve is required.

2.2

Utility Header At unit battery limit, provide isolation valves as below: • For steam, fuel gas, steam condensate, boiler feed water & hydrogen, provide double block valves, blind & ¾” bleed. For HP steam, also provide a 1” warm-up bypass. • For instrument/plant air, service water, nitrogen, cooling water etc., provide a single valve, blind and ¾” bleed.



3.0

Connection for Instruments

3.1

Instrument Connection Size (for guidance only) S. No.

Instrument

1

Thermowell

2

Pressure Instrument/Differential Pressure (Direct Type, Pipe Mounted) Pressure Instrument/Differential Pressure (Direct Type, Equipment Mounted) Pressure Instrument • Diaphragm Seal, Pipe • Diaphragm Seal, Vessel Differential Pressure (Diaphragm Seal) Standpipe • Upto 330# Ratings • 600# and above ratings Level Gauge (On Vessel) Level Gauge (On Standpipe) Displacer Level TX (Vessel/Stand Pipe External) Displacer Level TX (Top, Internal) Level Switch (Vessel, S/P) External Annubar O2 Analyser (On Stack) Analysers (Others Except ‘B’) Sample Probe

3 4

5 6

7 8 9 10 11 12 13 14 15

First Isolation Connection (Piping / Vessels) 2” Flanged *

Instrument Connection

¾” Welded

2” Flanged Temperature Element Connection to Thermowel ½”. ½” NPT

2” Flanged *

½” NPT

2” Flanged ** 2” Flanged * 3” Flanged

2” Flanged ** 2” Flanged * 3” Flanged

3” 4” 2” Flanged * ¾” Flanged * 2” Flanged *

¾” Flanged ¾” Flanged 2” Flanged *

4” Flanged * 2” Flanged *

4” Flanged * 2” Flanged *

2” Flanged * 4” Flanged ** 3” Flanged ** 2” Flanged **

½” NPT (Pressure Tap)

* Flange rating shall be min 300# ** Flange rating as per Pipe Specification

4.0

Equipment Sparing Philosophy The Following equipments shall be provided with a spare: • • • •

Main Process Pumps viz. Feed Pumps, Product pumps, reflux pumps and transfer pumps Reciprocating Compressors All Control Valves shall be provided with manual bypass globe valve unless provided with handwheel Filters where duplex is specified or where additional Filter is required owing to process reasons.



5.0

Equipment Duty Margins Equipment duty margins (between normal and design duties) are specified on the process data sheet. In case of new equipment, duty margins are allowed as follows as minimum requirement.

5.1

Heat Exchanger (Shell and Tube) A nominal over surface, based on either 10% on flow and / or duty will be used depending on if the services is critical or non critical, in consultation with the Customer.

5.2

Air cooler Use similar approach as above.

5.3

Fired Heaters Use similar approach as above. Notes: • For fuel fired heaters a maximum of 25% excess air is allowed. • For gas fired furnaces the excess air is 15%.

5.4

5.5

Pumps Centrifugal Pumps

: For small process pumps and reflux pumps use 20% margin on normal flow. For large pumps, use 10% of normal flow.

Reciprocating Pumps

: Use 10% of normal flow for both small and large pumps.

Compressor For both centrifugal and reciprocating compressors, use 10% margin of normal flow. For air blower use 10% margin on normal flow.

6.0

Pressure Relief Philosophy All relief valves load and size shall be calculated according to the following mentioned codes: • • • • •

API 520 API 521 API 526 API 527 API 2000

The size of relief valves are based on either over-pressure condition, fire exposure or vacuum situation for a particular system.



6.1

Typical over pressure conditions is:             

6.2

Typical vacuum considered would be:       

6.3

Blocked Discharge Inadvertent Valve Opening Utility Failure Cooling Water Failure Electrical / Mechanical Failure Loss of Air Cooler Fans Loss of Heat in Fractionation Loss of Instrument Air or Electric Power Instrument Failure or Blow-by Reflux Failure Abnormal Heat Input From Reboilers Heat Exchanger Tube Failure Trapped Liquid Expansion

In-breathing due to pumps out and temperature variation Steam condensation (Vacuum arising from steam out under maintenance conditions not be considered for vacuum relief protection) Equipment normally operating under vacuum Equipment operating under vacuum conditions during start-up, shutdown, regeneration, or evacuation Liquid full vessels that can be blocked in, and cooled Distillation columns and associated equipment that can be subjected to vacuum due to loss to heat input. Pressure vessels containing liquid having vapour pressure at minimum ambient temperature less than atmospheric pressure.

Relief Valve Selection Type Balanced bellow will be used for the cases where the built-up backpressure and the variable superimposed backpressure exceeds 10%, but is below 50% of the set pressure. Pilot operated relief valves may be used for systems when maximum set point accuracy is required. They will be installed in equipment, which operate very close to set pressure. All above valves are also limited by process considerations (i.e. H2S service etc.) and material. Notes: 1. Valve selection will be based on maximum operating temperature and relief valve set pressure. 2.

Where H2S is present, process data sheet will contain a note to indicate its presence.

3.

Safety valves on column circuits are preferred to be located at the highest point in the overhead vapors lines. Alternatively, these safety valves can be located as per below provided that the pressure drop in the inlet line is within 3% of set pressure.

4.

PSV discharge to be free draining to flare header, and join at 45o angle for 2” and larger size and 90o and free draining towards flare header for 1 ½” and higher size.



5.

Inlet and outlet valve to be full port.

6.

Relief valves on highly viscous fluid lines to be steam jacketed.

7.

Relief valves, which are susceptible to plugging, shall be steam traced and have a rupture disc installed under them.

8.

Staggered pressure setting may be specified to minimise losses.

9.

For atmospheric relief, the open end of discharge will be located 30m from any source of ignition. Discharge is usually 3m higher than any equipment or manholes (Ladder, platform etc.) within 15m radius

NO POCKETS

FREE DRAINING FREE DRAINING

COLUMN

FLARE HEADER

CONDENSER

REFLUX DRUM SUFFICIENTLY HIGH TO AVOID LIQUID ACCUMULATION. ALSO ENSURE SAFETY VALVES ACCESSIBILITY FOR MAINTENANCE

7.0 Insulation and Tracing Philosophy To reduce heat loss, piping, vessels, tanks and the equipment will be insulated where operating temperature exceeds 70oC. The table showing insulation thickness with temperature is below:



Table - 1 Insulation Thickness for Personal Protection Insulation thickness in mm Surface temperature of insulation less than 60°C Nom Dia. (in) 0.5 0.75 1 1.5 2 3 4 6 8 10 12 14 16 18 20 Flat Surface

Upto 125 25 25 25 25 25 25 25 25 25 25 25 25 25 25 25 25

126 150 25 25 25 25 25 25 25 25 25 25 25 25 25 25 25 25

151 200 25 25 25 25 25 25 25 25 25 25 25 25 25 25 25 25

Operating Temperatures in ° C 201 251 – 301 351 250 300 350 400 25 25 25 40 25 25 25 40 25 25 40 40 25 25 40 50 25 25 40 50 25 40 50 50 25 40 50 65 25 50 50 65 40 50 50 75 40 50 50 75 40 50 65 75 40 50 65 75 40 50 65 80 40 50 65 80 40 50 65 80 40 50 65 80

401 450 50 50 50 50 65 65 75 75 80 80 90 90 90 90 90 90

451 500 50 50 65 65 75 75 80 90 100 105 115 115 115 115 115 115

501 550 65 65 65 75 80 90 105 105 115 125 125 130 130 140 140 140

Types of Insulation Materials Bonded Mineral Wool pipe sections (MW) Bonded Mineral Wool mattress (MW) Cal. Silicate Pipe Sections (Cal. Sil) Cal. Silicate Lags (Cal. Sil)



Table - 2 Insulation Thickness for Heat Conservation Insulation thickness in mm Heat Loss = 150 Kcal/hr-m2 (max) Nom Dia. (in) 0.5 0.75 1 1.5 2 3 4 6 8 10 12 14 16 18 20 Flat Surface

Upto 125 25 25 25 25 25 25 25 25 25 25 25 25 25 25 25 25

126 150 25 30 30 30 30 35 35 35 40 40 40 40 40 40 40 40

151 200 35 40 40 45 45 50 50 55 55 55 60 60 60 60 60 60

Operating Temperatures in ° C 201 251 – 301 351 250 300 350 400 50 60 70 85 50 65 75 90 55 65 80 95 60 70 85 100 60 75 90 105 65 80 100 115 70 85 105 120 75 90 110 130 75 95 115 140 80 100 120 145 80 100 125 150 80 105 125 150 85 105 130 155 85 105 130 155 85 105 130 155 85 105 130 155

401 450 95 100 105 115 120 135 140 155 160 170 175 175 180 185 185 185

451 500 110 115 125 130 140 150 150 160 175 185 195 200 205 210 215 215

501 550 115 125 125 140 150 150 150 165 180 190 200 210 210 220 220 220

Types of Insulation Materials Bonded Mineral Wool pipe sections (MW) Bonded Mineral Wool mattress (MW) Cal. Silicate Pipe Sections (Cal. Sil) Foam Glass pipe sections (upto 125 °C only) (FG) Notes: 1. Applicability for thermal insulation Temp. range 60 to 550 °C For Pipes, Ductwork and Equipment. NOT applicable for Embedded/Buried lines, buildings and structures. 2. For operating temperatures above 550°C, decide material and thickness on case to case basis.



Table - 3 Insulation Thickness for Cold Insulation Nom Dia. (in) 0.5 0.75 1 1.5 2 3 4 6 8 10 12 14 16 18 20 Flat Surface

Upto +5

+4 to -7

-8 to -18

-19 to -32

35 40 40 45 45 50 55 60 60 65 65 65 65 70 70 70

50 50 55 60 65 70 75 80 85 90 90 90 95 95 95 95

60 65 70 75 80 90 95 100 110 115 115 120 120 125 125 125

80 80 85 95 100 110 115 130 135 140 145 150 155 155 160 160

Operating Temperatures in ° C -33 to -46 to -61 to -76 to -91 to -45 –60 -75 -90 -100 90 95 105 115 120 130 140 150 160 170 175 180 185 185 190 190

110 120 125 135 145 160 170 185 195 205 215 220 225 230 230 230

125 135 140 155 165 180 190 210 225 235 240 245 255 260 265 265

145 155 160 175 185 205 220 240 255 265 275 280 290 295 300 300

155 165 170 190 200 220 230 255 270 280 290 300 305 315 320 320

-101 to -120 165 175 185 200 215 235 250 275 290 305 315 315 320 330 340 345

-121 to -130 170 180 190 210 220 240 255 280 300 310 325 330 340 350 355 355

-131 to -145 180 185 195 215 225 250 265 290 305 320 335 340 350 360 365 365

-146 to -155 180 190 200 220 230 255 270 295 310 325 340 345 355 365 370 370

Types of Insulation Materials  Rigid Polyeurethene Foam Tracing In case of tracing, steam or electrical tracing shall be used.



8.0

Process Block Valves Philosophy

8.1

Single Block Valves Single block valves shall be installed for the following conditions:       

 

 8.2

In piping at all vessels and tanks nozzles, where the nozzle is below liquid level of the vessels and tanks. In exchanger inlet and outlet, only if exchanger requires frequent inspection or cleaning. In suction and discharge piping of pumps, turbines and compressors. At equipment in auxiliary piping for gland oil, flushing oil, cooling water and for removal of equipment. At equipment in steam piping for steam driven equipment. At fuel oil and fuel gas piping to furnaces or fired heaters. Valve shall be located 15m from the equipment and accessible for rapid operation in emergency. For drains to closed drain header. Install a check valve, one pair of flanges and a bleed valve upstream of block valve. (Note: Flanges and bleed to be provided between check and block valves.) In product lines to slop header. Install a check valve and block valves. For gas stream <100 barg pressure or liquid system of <60 barg pressure. If the operations will be more frequent than twice per annum, or the system contains gases or liquids, which are potentially toxic, then a double block and the bleed system will be used. In lines to flare header

Double Block Valves Double block valves shall be installed for the following conditions:   

  

9.0

For cases where cross contamination cannot be tolerated. For vents and drains in ANSI Class 600 rating and over. For drains containing C5 (plus lighter hydrocarbons) or lighter hydrocarbons. In this case the double block valves must be minimum of 100cm straight pipe apart. A check valve will be installed upstream of the first block valve. A pair of flanges shall be provided between the check and first block valve. Where high pressure (above ANSI CI 300 rating) is likely to be removed on the run; e.g. spared machinery or equipment. For gas stream >100 barg or liquid systems > 60barg or gas/liquids which are potentially toxic. For the equipment which may be opened for maintenance “ on the run” (e.g. filters).

Utility Station Location Philosophy Utility steam, air and service water outlets shall be furnished with hose connection of minimum size 1” nominal. As a general rule provide first block valve (ideally at header) followed by a ¾” bleeder, check valve and block valve adjacent to equipment or piping. All utilities are to terminate with a hose connection (Assuming a maximum hose length of 25m, utility stations for LP steam, service water and plant air shall be provided at following locations:



In Process Units    

At grade to serve equipment within a maximum 25m radius. At top platforms of drums located at the grade. At first level platforms of structures and towers. At second level platforms of structures and towers.

In Off-Sites 

10.0

Utility stations will be provided near pump stations and chemical injection systems. (Direct connections from utility header to process vessels must be avoided to stop process fluid entering into utility system.

Isolation Blinds / Spading Philosophy Isolation blinds will be provided as follows:    

On all spared pumps, turbines and compressors on the equipment side of the block valve, where applicable. At unit limits either between double blocks or on unit side. (refer Section 2.0). At equipment, which can be physically entered, provision for temporary blinds. For vents and drains- provision for temporary blinds.

Nominal Line Size (Inches) 12” and under Over 12” inches

11.0

Blind Type Spectacle Blind Circular with spacer

Tank Fittings and Accessories Philosophy The following guidelines will be used (as a minimum) during detail engineering to specify fittings and accessories for all types of atmospheric tanks.

11.1

Manholes – Number and Sizes Shell Nominal Tank Dia. (Meters) 3 to 6 > 6 to 12 >12 to 18 >18 to 45 >45

All Tanks Types

Roof

Roof

Fixed Roof Tanks

Floating Tank

Internal Floating Roof Roof

Fixed Roof

Number

Size (inch)

Number

Size (inch)

Number

Size (inch)

Number

Size (inch)

1 2 2 2 3

24 24 24 24 24

1 2 2 2 2

24 24 24 24 24

1 1 1 2 2

24 24 24 24 24

1 2 2 2 3

24 24 24 24 24

Internal Floating Roof Size Number (inch ) 1 24 1 24 1 24 2 24 2 24



11.2

Filling and Suction Nozzles – Minimum Sizes Nominal Tank Diameter (meters) <14.9 15.2 to 30.1 30.4 to 60.5 >61

11.3

Roof Drains Nominal Tank Diameter (meters) <6 6 to 18 > 18

11.4

Nozzle Diameter (Inch) 3 4 6 8

Drain Diameter (Inch) 3 4 6

Sample / Gauge Hatch Provide one 8” gauge hatch for level measurement per tank.

11.5

Water Draw-off/Drain – Number and Sizes All draw-off connection shall be furnished complete with the following: 4” nozzle, 1200mm diameter by 610mm deep-water draw-off sump, internal pipe terminating 100mm above bottom of sump and drain valve. Nominal Tank Diameter (meters) <12 12.1 to 45 46 to 61 >61

Number Required 1 2 3 4

Water draw-off nozzles shall be located near shell manholes to facilitate cleaning of sumps.

12.0

Equipment Design Philosophy

12.1

Pressure Vessels Design Design Pressure The design pressure for pressure vessels shall be as per the following criteria:

a. For operating pressures upto 70 kg/cm2g, the highest of the following to be considered :



• • •

Maximum Operating Pressure + 2.0 kg/cm2 Maximum Operating Pressure x 1.1 3.5 kg/cm2 (g)

b. For operating pressures above 70 kg/cm2g : • •

For operating pressures between 70 and 140 kg/cm2g : Operating Pressure + 7.0 kg/cm2 For operating pressures greater than 140 kg/cm2g : Operating Pressure x 1.05

c. For vessels operating under vacuum, design pressure to be 1.0 kg/cm2g and full vacuum. Notes: 1. For equipment connected to flare (e.g, flare knockout drum), design pressure of equipment to be same as flare design pressure. 2. Equipment in circuits that can be evacuated by an ejector and suction drum on reciprocating compressor will be designed for full vacuum conditions in addition to operating conditions. Strippers using steam will be designed to full vacuum conditions. 3. Mal-operation during the steam out of vessels is not to be considered. 4. The vessels open to atmosphere shall be designed for full of water condition. 5. Design pressure mentioned above does not include the liquid head. Design Temperature The equipment design temperature shall be as follows:   

For temperature below 0o C For temperature above 0oC Boiling water service

: Lowest possible operating temperature : Operating Temperature + 30oC : Saturation temperature at design pressure.

Note: For exchangers, pumps, compressors, filters, etc., use as above pressure vessel design temperature 12.2

Pump Shut Off Equipment in a pump discharge circuit with a down stream block valve shall have a design pressure which should be the higher of the two : - suction vessel operating pressure + normal liquid static head pressure -

+ pump differential shut-off

suction vessel design pressure + maximum liquid static head + pump differential pressure (at normal flow)

For estimates of pump shut off head on motor driven centrifugal pumps at normal operating suction pressure, use the suction pressure plus 1.25 times the rated differential pressure of pump. The suction pressure shall be the vessel normal operating pressure plus the normal liquid static head. For constant speed turbine driven pumps, use the suction pressure 1.35 times rated differential pump pressure. For variable speed turbine pumps, uses the suction pressure plus 1.5 times rated differential pump pressure.



For a full liquid system at the discharge of a positive displacement pump, the mechanical design pressure shall be higher of these two: • •

P (rated) discharge + 2 kg.cm2 P (rated) discharge * 1.1

The shut off pressure will be confirmed based on equipment purchased. 12.3

Tank Design The minimum design pressure and design temperature requirements of tanks shall be as below: Design Pressure Cone Roof Tank Dome Roof Tank

: :

+20 mbarg / -6 mbarg 0.04 to 1.04 barg

Tank design pressure does not include liquid head. Design pressure is for the top of the tank. Maloperation during steam out is not to be considered. A vacuum breaker shall be provided. Blanketed storage tanks shall have a blanketing pressure of 150 mmwc unless specified by client. Design Temperature The tanks design temperature shall be as follows:   

For temperature below 0o C For temperature above 0oC Boiling water service

: Lowest possible operating temperature : Operating Temperature + 30oC : Saturation temperature at design pressure.

The minimum design temperature shall be the lowest temperature expected in service. 12.4

Tower Overhead System For equipment in a tower overhead system with a relief valve, the design pressure shall be arrived as follows: a) b)

12.5

In front of a train of equipment, design pressure to be compatible with the relief valve set pressure plus liquid static head. In rear of a train of equipment, design pressure to reflect relief valve set pressure, liquid static together with line and equipment pressure losses, including fouled equipment.

Compressor Systems For centrifugal or axial compressor, the design pressure of upstream equipment should be set at a safe margin above the settle-out pressure. The safe margin is normally at least 10%. Downstream equipment will be set at blocked in conditions. For reciprocating compressors, each stage is fitted with safety valve at a margin above the normal discharge pressure by the vendor. The piping and equipment downstream will be set at blocked-in



condition. The upstream equipment will be set at in the usual way, above the normal operating pressure or the settle out pressure and protected by relief valve. 12.6

Piping Systems Design pressure for the piping will normally be at least equal to theoretical maximum expected operating pressure and similar to the connected equipment. Design temperature for the piping will take into consideration flowing conditions, shut conditions and solar radiation and will be similar to the connected equipment. For relief valve inlet pipe, design temperature and pressure will be same that of the connecting equipment. For discharge pipe, design temperature must be determined separately.

12.7

2/3rd Rule for Heat Exchangers For shell and tube heat exchangers the low-pressure side shall be specified for a mechanical design pressure at least equal to 2/3rd of high-pressure side mechanical design pressure. If this is not possible, a relief valve of adequate size must protect the low-pressure side. 2/3rd rule shall necessarily be adhered to when: • LP fluid is on tube side • Relief discharge cannot be connected to flare header owing to nature of fluid • Relief discharge is two phase and cannot be connected conveniently to a low-pressure destination with free-draining piping. • Liquid relief cannot be connected to CBD system • When the 2/3rd criteria calls for an increase by less than a factor of 1.5 of the mechanical design pressure of the LP side as would be calculated from normal estimation procedures.

13.0

Minimum Liquid Surge Requirement The “liquid surge volume” within a vessel is determined by the following factors:  The control range  The manual intervention range  The required residence time for separation, degassing, etc.  The possibility of liquid slugs in the feedline. The surge time shall not be confused with residence time as surge time is hold up time between two level, usually HLL and LLL, while residence time is hold up time from NLL to empty vessel. The guidelines for Surge time is given below: Service Feed to unit Product to storage Feed to tower Feed to furnace Compressor suction Manual control and manual intervention

Surge time (minutes ) LLL to HLL 15 – 20 2 5–7 4 – 10 5 20

Level transmitters and level gauges shall cover the cut-off point (low-low / high-high) also



14.0

Utility Conditions The plant utility conditions are project specific. However, The Typical utility conditions for the plant is given below for guidelines only: S. No.

Parameter

1

High Pressure Steam (HP) * Pressure, kg/cm2 38 40 Temperature, oC 380 390 Medium Pressure Steam (MP) * Pressure, kg/cm2 12 14 Temperature, oC 210 290 Low Pressure Steam (LP) * Pressure, kg/cm2 3 4 Temperature, oC 143 175 Condensate Return (Suspect / Pure) * Pressure, kg/cm2 8.5 / 6 Temperature, oC 40 / 90 Service Water Pressure, kg/cm2 3 5 Temperature, oC Ambient Cooling Water* Supply Pressure, 4 4.5 kg/cm2 Return Pressure, 2.2 2.5 kg/cm2 Supply Temperature, 28 33 o C Return Temperature, oC 45 Demineralised Water * Pressure, kg/cm2 4 7.5 Temperature, oC 30 40 Boiler Feed Water (HP / MP) * Pressure, kg/cm2 47/25 50/28 Temperature, oC 100 Plant Air (Oil and water free) * Pressure, kg/cm2 4 5 Temperature, oC 40 Instrument Air * Pressure, kg/cm2 5 6 Temperature, oC Dew Point Fuel Gas Pressure, kg/cm2 2 3 Temperature, oC 35 45 Fuel Oil (@ BL / @ burner) * Supply Pressure, 8 /6.4 10/8.4 kg/cm2 Return Pressure, -/2.5 -/3.5 kg/cm2

2 3 4 5 6

7 8 9 10 11 12

Minimum

Normal

Maximum

Mechanical Design

42 400

46 420

15 305

18 350

4 190

7 240

100 / 100

150

6

10 65

5

7

2.8

7 65

45

65

8 45

12 65

-/35 100-110

- /40 150

8 50

10 65

7 = (-) 40

10 65

4.5 55

6.5 65

12/10.4

18

-/3.5

18



13

Temperature, oC Nitrogen * Pressure, kg/cm2 Temperature, oC

140

210

240

260

4

6 40

7 10.5 Dew Point = (-) 100 atmospheric pressure

o

C at

* The operating and design conditions are typical and tentative and shall not be used for design purposes. For actual utility conditions please refer project design basis of the specified project.

15.0

Noise Control Sound Level Limits for Personnel All process units should conform to a work area limit of 90 dBA. The maximum eight-hour exposure level for personnel exposure shall not exceed a continuous sound pressure level of 87dBA. This limit does neither apply to locations where excessive noise exposure is infrequent, or to non-recurring operating conditions such as venting. At no time shall personnel be exposed to sound- levels in excess of 115 dBA. Hearing protection does not alter this requirement. Area Sound Level Limits The following limits shall apply to all plant areas and buildings. Executive office, conference rooms Semi-private offices, small conference rooms General offices, laboratories Control rooms Workshop offices Personnel shelters Workshops, machine rooms Operating areas within 15m of permanent operator's station or maintenance station

35 dBA 45 dBA 50 dBA 55 dBA 65 dBA 70 dBA 75 dBA 85 dBA

Noise reduction The following methods will be considered for noise reduction. Heaters : Intake / outlet silencers, Acoustic lining / lagging Motors : Low noise motors or enclosures Air Cooled Heat Exchangers : Decrease tip speed, Hub seals, Acoustic shrouds on gear or belt drives, Low noise motors Compressors : In line silencers Lagging Acoustic Enclosures Valves : Low noises trim Acoustic lagging Silencers Vents : Silencers Flares : Acoustically baffled multi-port nozzles

Plant Fence Line Noise Levels



Plant fence line noise levels shall not exceed the following: Leq LIO

72dBA 75dBA

Where Leq is the equivalent continuous equal energy level. LIO is the 10% excess sound level. During the detailed engineering phase of the project noise shall be further controlled by placing limitations on the suppliers of new equipment and for the refurbishment of existing equipment where applicable. Meteorological Conditions The pertinent data shall be referred from Project Design Basis, to be provided by the client.

16.0

Aromatics Handling Special precaution shall be given when handling the process streams containing Aromatics (Carcinogen) with following specifications: • Benzene content greater than 1% by weight • C6 through C9 aromatics greater than 25% weight • Butadine content greater than 5% by weight In handling these streams following precautions shall be taken: • •

17.0

Pumps shall be dual mechanical seals The followings shall be connected to closed blowdown system 1. Vessel drains 2. Pump drains 3. Control valve, level gauge and level instrument drains.

Corrosion Allowance The minimum corrosion allowance shall be as per the following table: Sl. No. 1 2 3 4 5 6 7

18.0

Service Carbon Steel Pressure Vessels Carbon steel atmospheric vessels Alloy steel vessels Stainless steel vessel Clad / lined vessels Carbon steel / LAS exchangers SS / HAS / Non ferrous exchangers

Corrosion Allowance (mm) 3 3 1.5 Nil 3 mm clad thk 3 Nil

IBR Requirements



The IBR requirements are as below: 

Vessels: Any closed vessel exceeding 22.75 litres in capacity which is used exclusively for generating steam under pressure and include any mounting or other fittings attached to such vessels, which is wholly or partially under pressure when steam is shut-off comes under IBR.



Piping  

: Any pipe through which steam passes and if : Steam system mechanical design pressure exceeds 3.5 kg.cm2g or Pipe size exceeds 254 mm internal diameter. Then the pipe is under IBR.



The following Items are not under IBR  Steam tracing  Heating Coils  Tubes of Tanks  Steam Jackets



All steam users (Heat Exchangers, vessels, condensate pots etc.) where condensate is flashed to atmospheric pressure i.e. downstream is not connected to IBR system are not under IBR and IBR specification is done at last isolation valve upstream of equipment. All steam users where downstream piping is connected to IBR i.e. condensate is flashed to generate IBR steam are covered under IBR. Deaerator, BFW pumps are not under IBR and IBR starts from BFW pump discharge.

 


76530132 Process Design Manual Lurgi

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