Internship Report: (Production Unit)

Internship Report (Production Unit)

Fauji Fertilizer Company | Mirpur Mathelo Batch 9 | Internship Summer 2010

INTERNSHIP REPORT (Production Unit) Prepared for Technical Training Centre (TTC) Fauji Fertilizer Company Ltd. (FFC) Mirpur Mathelo, District Ghotki (Sindh)

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1 Declaration July 28, 2010

TO WHOM IT MAY CONCERN

Dear Sir: Submitted for your review is the report of my four week internship (Batch 9) at Production Unit of Fauji Fertilizer Company Ltd. Mirpur Mithalo plant, during July 2010. It is hereby declared that the report is compiled in long report format, as per the guidelines and is based upon the literature review; plant manuals and standard operating procedures; process flow diagrams and sharing and learning from management and staff of the company. Maximum possible references from literature are cited and sources are mentioned.

Internship ’10 Report (Production Unit)

2 Acknowledgements Author is thankful to Almighty Allah,

For His unlimited blessings and bounties, And for keeping him sane, sound and successful; His parents and friends,

For all their support and trust in him and his aims; His teachers and guides,

For teaching him things he knew not; NUST Internship and Placement Placement Office,

For bringing the opportunity of this excellent learning and exposure; And last but never the least

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3 Table of Contents 1

Declaration ...............................................................................................................................ii

2

Acknowledgements Acknowledg ements ...................................................... .......................................................................................................... ........................................................... .......iii

3

Table of Contents .................................................................................................................... iv

4

List of Figures .......................................................................................................................... vi

5

List of Tables .......................................................................................................................... vii

6

List of Acronyms .................................................................................................................... viii

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Abstract ................................................................................................................................... ......................................................................................... .......................................... ix

Introduction .................................................................................................................................... 1 8

Literature Review .................................................................................................................... 2 8.1

Fertilizer ............................................................................................................................ 2

8.2

Ammonia Manufacture .................................................................................................... 2

8.3

Urea Manufacture ............................................................................................................ 3

8.4

Industrial Water ............................................................................................................... 4

8.4.1

Problems ................................................................................................................... 5


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9.2.2

Use of Personal Protective Equipment ................................................................... 26

9.2.3

Use of Fire Extinguishers ......................................................................................... 26

9.2.4

Ammonia Disaster ................................................................................................... 28

Production Unit ..................................................................................................................... 29

10.1

Utilities Unit ................................................................................................................ 29

10.1.1

Water Treatment (Area 09) .................................................................................... 30

10.1.2

Cooling Tower System (Area 08) ............................................................................. 37

10.1.3

Waste Water Disposal (Area 16) ............................................................................. 39

10.1.4

Instrument Air Compression (Area 10) ................................................................... 40

10.1.5

Natural Gas Station (Area 15) ................................................................................. 41

10.1.6

Auxiliary Boilers (Area 06) ................................................................................... 42

10.1.7

Power Generation (Area 07) ................................................................................... 43

10.2

Ammonia Unit ............................................................................................................. 45

10.2.1

Desulfurization Section (Area 02) ........................................................................... 45

10.2.2

Reforming Section (Area 02) ................................................................................... 47

10.2.3

Gas Purification Section (Area 03) .......................................................................... 50

10.2.4

Ammonia Synthesis Section (Area 05) .................................................................... 55

10.3

Urea Unit..................................................................................................................... 60


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Appendix III ..................................................................................................................................... C FFC MM Plant Safety Rules and Regulations .................................................................................. C

Appendix III ..................................................................................................................................... D Process Flow Diagrams ................................................................................................................... D

4 List of Figures Figure 1 Ammonia Manufacture from Hydrogen and Nitrogen by Haber Process ........................ 3 Figure 2 Urea Production from Ammonia and Carbon dioxide ...................................................... 4 Figure 3 ClarificationTank ............................................................................................................... 8 Figure 4 Sand Filters ........................................................................................................................ 9 Figure 5 Process Safety Control Hierarchy.................................................................................... 12 Figure 6 Emergency Direction Signboard (FFC, MM).................................................................... MM).................................................................... 13 Figure 7 Internee Personal Protective Equipment (PPE) .............................................................. 15 Figure 8 Types of Plant Operation ................................................................................................ 18 Figure 9 Fire Triangle .................................................................................................................... 19 Figure 10 Fire Extinguisher Labels ................................................................................................ 20 Figure 11 Emergency Siren Sequence (FFC Safety Section, 2004) ................................................ 26 Figure 12 Emergency Response (FFC Safety Section, 2004) ......................................................... 27 Figure 13 PASS Approach for Using Fire Extinguisher .................................................................. 27


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5 List of Tables Table 1 Degree of Hardness ............................................................................................................ 6 Table 2 Alkalinity Indication (Utilities Unit, 2009) .......................................................................... 6 Table 3 Water Quality Comparison................................................................................................. Comparison................................................................................................. 7 Table 4 National Electrical Code, NEC (National Fire Protection Association, 2002) ........ ............... ........... .... 17 Table 5 Classification of Fire (OSU, 2005) ..................................................................................... 20 Table 6 Safety Description as set by Safety Section, FFC MM ...................................................... 25 Table 7 Strategy in Fire Incident (Suggested by Safety Section, FFC MM) ............... ..................... ............. .............. ....... 26 Table 8 Effect of Ammonia at Differenct Concentrations in Air ................................................... 28 Table 9 Plant Utilities Division ...................................................................................................... 30 Table 10 Chemical Dosage in Clarifier .......................................................................................... 32 Table 11 Clarified Water Parameters............................................................................................ 33 Table 12 Mineral Ions in Water .................................................................................................... 35 Table 13 Cooling Tower Design Data ............................................................................................ 38 Table 14 NEQS Limits for Water Water Disposal .......................................................................... 39 Table 15 Natural Gas Composition ............................................................................................... 46 Table 16 Syn Gas Recycle Composition ........................................................................................ 46 Table 17 Gas Compositions after Primary Reformer F-201 .......................................................... 49 Table 18 Gas Compositions after Secondary Reformer R-203 ..................................................... 50 Table 19 Gas Compositions after HTS Convertor R-204 ............................................................... 52 Table 20 Gas Compositions after LTS Convertor R-205 ................................................................ 52


6 List of Acronyms BFW

Boiler Feed Water

CCR

Central Control Room, FFC MM

DCS

Distributed Control System

DMW

De-mineralized Water

DO

Dissolved Oxygen

DS

Dissolved Solids

EDG

Emergency Diesel Generator

EPA

Environment Protection Agency

FFC MM

Fauji Fertilizer Company Ltd. Mirpur Mathelo

FFC

Fauji Fertilizer Company Private Limited

HP

High Pressure

HS

High Steam

IMS

Integrated Management System

LP

Low Pressure

LPD

Low Pressure Decomposer

LS

Low Steam

LTA

Lost Time Accident

MC

Medium Condensate

MP

Medium Pressure

MPD

Medium Pressure Decomposer

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7 Abstract Production unit manages the urea (product name: Sona urea) production from ammonia and carbon dioxide, synthesized from natural gas and atmospheric air. The unit is divided into:



Utilities unit; provides plant utilities like electricity, cooling water, instrument air etc



Ammonia unit; produces ammonia and carbon dioxide from natural gas and atmospheric air



Urea unit; produces urea by dehydration of carbamate, made by reaction of liquid ammonia and carbon dioxide gas



Bagging and shipment unit; unit; bags the urea product and sends it to the consumer market market

Utilities unit has the most diverse ground of operation ranging from water treatment to steam generation, boiler operation to power generation, cooling tower to waste water treatment. Ammonia unit has the maximum learning exposure with catalytic steam reforming, carbon


Introduction You cannot create experience, you must undergo it. Internships are supplemented to course work for enhancement of practical knowledge and expertise of students. Fertilizer being a major component of chemical industry has a lot to develop an understanding understanding of a chemical engineering student, varying from unit operations to processes and transport phenomena to chemical reaction engineering.

FFC is a leading fertilizer production group in Pakistan, with over 60 % market share in the sector. Incorporated in 1978 as a private limited company, it is a joint venture between Fauji Foundation and Haldor Topsoe of Denmark. Since Pakistan is an agro-based economy, the contribution of the fertilizer to the economy is vital and FFC is a prime share holder in the fertilizer industry of Pakistan. At present the foundation has three fertilizer plants one at Goth Machi, second at Mirpur Mathelo and third in Karachi named FFBL (formerly FFC-Jordan

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8 Literature Review 8.1 Fertilizer Fertilizers are used to provide plants with nutrients, not available with soil. They improve plant health, its tolerance against pets and enhance appearance. Basic plant needs include: 

Oxygen



Water



Sunlight



Nutrients and



Growing medium

Plant nutrients are further classified into: macro-nutrients (primary), macro-nutrients (secondary) and micro-nutrients (minor). Primary macro-nutrients include nitrogen, phosphorous and potassium, while the secondary include calcium, magnesium and sulfur. Micro-nutrients have a long list including iron, zinc, manganese, copper, boron, molybdenum, chlorine etc but in very small quantities. Nitrogen is the key element in plant nutrition. It promotes stem and leaf growth and is an essential component of chlorophyll molecule. It is also involved in regulating intake of other nutrients. Fertilizers have been extensively used in agriculture for better growth of food and cash crops. Urea (% nitrogen) is one of the most used fertilizers in Pakistan. Made from liquid ammonia


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N2 + 3H2 → 2 NH3

F IGURE 1 A MMONIA M ANUFACTURE FROM H YDROGEN AND N ITROGEN BY H ABER P ROCESS

In the Haber’s process, the reaction of nitrogen and hydrogen gases is accomplished a ccomplished by feeding

the gases to the reactor at 400 °C to 600 °C. The reactor contains an iron oxide catalyst that reduces to a porous iron metal in the nitrogen/hydrogen mixture. Exit gases are cooled to – 0 °C to – 20 °C, and part of the ammonia liquefies; the remaining gases are recycled. The process varies somewhat with source of hydrogen, but the majority of ammonia plants generate hydrogen by steam reforming of natural gas or h ydrocarbon such as naphtha. naphtha. If the hydrogen is made by steam reforming air is introduced at the secondary reformer stage to provide nitrogen for the ammonia reaction. The oxygen of air reacts with the hydrocarbon feedstock in combustion and helps to elevate the temperature of reformer. Otherwise nitrogen can be added from liquefaction of air. In ei ther case a nitrogen-hydrogen mixture is furnished


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NH2COONH4 →NH2CONH2 + H2O Both are the equilibrium reactions. The formation reaction goes to virtual completion under usual reaction condition, but the decomposition reaction is less complete. Unconverted carbon dioxide and ammonia along with undecomposed carbamate carbamate must be recovered and reused. In the process, a 2:1 molar ratio of the ammonia and carbon dioxide (excess ammonia) are heated in the reacted for two hours at 190°C and 1500 – 3000 psi (10.3 to 20.6 MPa) to form ammonium carbamate, with most of the heat of reaction carried away as a useful process stream. The carbamate decomposition reaction is both slow and endothermic. The mix of unreacted reagents and carbamate flows to the reactor – decomposer. The reactor must be heated to force the reaction to proceed. For all the unreacted gases and undecomposed carbamate to be removed from the product, the urea must be heated at lower pressure (400 kPa). The reagents are reacted and pumped back into the system. Evaporation and prilling or granulating produce the final product.

F IGURE 2 U RE A P RODUCTION FROM A MMONIA AND C ARBON DIOXIDE


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causes fouling which makes periodic cleaning necessary. Suspended particles also cause erosion in narrow passages or turns in the flow. Microbiological growth in water can also plug the narrow passages in the system. Similarly, oxygen content in water can become a cause of corrosion and reduces equipment life. In order to secure the equipment and maintain its smooth operation, water is treated and them used by the plant. Water treatment reduces turbidity, TDS, DS, DO, organic matter, hardness and color of water. Different unit operations are applied often in series to make water usable by plant.

8.4.1 Problems 8.4.1.1 Hardness Water becomes hard due to the presence of carbonates, carbonates, bicarbonates, chlorides and sulfates of metal ions like calcium, magnesium, iron, manganese, aluminum and barium. The former two cause temporary hardness and the later two are reason for permanent hardness. . Since the concentration of calcium and magnesium salts is usually much higher than concentrations of other compounds which impart hardness, it is customary to consider only the hardness caused by these salts (Utilities Unit, 2009). Calcium is dissolved as it passes over and through lime stone deposits. Magnesium is dissolved as it passes over and through dolomite and other Magnesium bearing formations. Hardness is reason for scaling or deposition of salts inside water pipes, eventually reducing


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T ABLE 1 D EGREE OF H ARDNESS

Ppm

75

Hardness

Soft

75 – 150

Moderate

150 – 300

Hard

Above 300

Very hard

Softening is the term which refers to the process of hardness removal.

8.4.1.2 Alkalinity Alkalinity is the capacity of water to neutralize acids. This is determined by the content of carbonate, bicarbonate, bicarbonate, and hydroxide. Expressed in ppm of calcium carbonate, it is a measure of how much acid can be added to a liquid without causing any significant pH change (Utilities Unit, 2009). It has two types: P – alkalinity and M – alkalinity. P – value is the measure of hydroxyl and carbonate alkalinity while M- value is the measure of total alkalinity. Phenolphthalein indicator enables the measurement of alkalinity contributed by hydroxide ions and half of carbonate ions. Any indicator responding in pH range 4 – 5 can be used to measure the total M – alkalinity. P – value and M – value determinations are useful for calculations of chemical dosage required in the treatment of natural water supplies. T ABLE 2 A LKALINITY I NDICATION (U TILITIES U NI T , 2009)

Alkalinity

Indication


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process more economical, if one alone does not give desired process optimization. Tube wells are only used when canal is nonfunctional, due to water shortage in country. T ABLE 3 W ATER Q UALITY U ALITY C OMPARISON

Surface Water

High Turbidity Low Hardness High TDS Acidic pH High Dissolved Gases

Underground Water

Low Turbidity High Hardness Low TDS Basic pH Low Dissolved Gases

8.4.2.1 Clarification Clarification is carried out in a cone-shaped clarifier that clarifies the source water through the addition of chemicals like lime, ferrous sulfate, chlorine and polyelectrolyte. Clarifiers purify water by precipitating and coagulating the impurities and removing them by sedimentation filtration (M. Yaqoob Ch., 1987). This results in removal of temporary hardness, turbidity and organic matter. It involves three steps: 1. Coagulation 2. Flocculation 3. Sedimentation Colloidal particles have large surface area that keeps them in suspension and a negative charge


Sedimentation is the settling of suspended particles to the bottom of the structure leaving behind clear water. Chlorine is added to water in order to kill the organic matter and oxidize the iron ions in water enabling their reaction with lime and settling. Lime removes temporary hardness caused by presence of bicarbonates salts. Lime reacts with dissolved carbon dioxide soluble bicarbonates to convert them into carbonates and hydroxyl salts are insoluble and therefore settle at the bottom of the tank. CO2 + Ca(OH)2 → CaCO3 ↓ + H2O 3+

2 Fe + 3 Ca(OH)2 → 2 Fe(OH)3 ↓ + 3 Ca

2+

Ca(HCO3)2 + Ca(OH)2 → 2CaCO3 ↓ + 2H2O Mg(HCO3)2 +Ca(OH) 2 → MgCO3 ↓ + CaCO3 ↓ + 2H2O MgCO3 + Ca(OH)2 → Mg(OH)2 ↓ + CaCO3 ↓

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batteries of two or more, these filters are often backwashed by forcing water in reverse direction. This flushes the solids trapped in and on the fi lter bed into waste disposal system. The flow of other cells is continued through when one cell of the fi lter is being backwashed.

Gravity Filter

Pressure Filter F IGURE 4 S AN D F ILTERS

8.4.2.3 Ion Exchange Demineralization is based on ion exchange process. Ion exchange is the displacement of one ion by another. It may also be defined as a reversible exchange of ions between a liquid and a solid phase (resin). This exchange does not involve any radical change in physical structure of the solid (resin). The ion exchanger or solid body must have its own ions to exchange for others. In


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cation exchanger will exchange all cations of both neutral and alkaline salts with the hydrogen ion. Weak Acid Cation (WAC) resins remove only cations associated with alkalinity. While WAC resins can remove mono-valent ions such as sodium associated with hydroxide alkalinity, in most water treatment applications they are used to remove divalent ions such as calcium associated with carbonate alkalinity. A weak acid cation exchanger will exchange cations of mainly alkaline salts, and to a very small extent, the cations of neutral salts. Most commercial ion exchange resins are synthetic plastic materials such as co-polymers of styrene and divinyl benzene. Strong Basic Anion (SBA) resins have strongly basic ammonium groups as the functional groups +

+

either with tri methylamine {(-CH2N (CH3)3)} OH- or with di-methylethanol amine {(-CH2N -

(CH3)2 C2H4OH) OH )} Groups both these types of strong base resins are used in the hydroxide form for de-mineralizing systems. Since strong base resins are highly ionized, they will exchange practically all anions which are present as both strong and weak acids, e.g. hydrochloric acid, sulfuric acid, nitric acid, carbonic acid and silicic acid. They will also split salts which remain unconverted in the cation exchanger. They are of two types of SBA resins: Type I SBA resins are used where low levels of silica leakage are important operating criteria or in warmer climates where source water temperatures may be quite warm for a significant part of the year. They operate at improved efficiency when warm caustic (120º F) is used to regenerate re generate the resin bed; Type II SBA resins resi ns have an exchange site that is chemically weaker than Type I resins. Therefore, they must be regenerated at lower


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about 120 percent of stoichiometry. Like their WAC counterparts, WBA resins can be regenerated using the spent caustic from the SBA resin bed making their use very efficient especially when used on water having a high percentage of anion loading fro m sulfate, chloride or nitrate. Mixed Beds provide optimum conditions for the ion exchange process and produces completeness of exchange with resultant treated water quality much better than could be realized in a multi bed deionizer. Polishing is carried out when it is necessary to get on high purity water. Resin structures classified according to their operating properties are: 

Styrene-divinyl benzene copolymer bead structure.

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Acrylic resin structure.

Physical classification of resins is: 

Gel resins; have smaller pores in the resin structure, higher initial exchange capacity and a lower purchase price

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Macro porous resins; have ability to elute foulants easier due to the larger pore structure, stand up better in harsher operating environments.

8.5 Safety Safety and well being of human and site re source is the paramount concern of any industry. It ensures maximum production and loss prevention and contributes to the well being of unit.


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Injury to personnel and property damage ask for high price, not the least of which are production break off and loss of trained man force and equipment. In USA, annual worker fatalities three out of a hundred thousand employees and annual lost-time disabling injuries are nine hundred (U.S. Bureau of Labor Statistics). However, annual property losses have increased fourfold from the 1970s to the present (Marsh & McLennan, Inc., Published Annually). This is probably because of increasing complexity and productivity of the highly automated chemical plants, where personnel are isolated from processes. Many changes have occurred in the requirements for safety in the chemical and petrochemical industries during the period from 1974 (Flixborough) to 1984 (Bhopal) to 1994 (Lodi, N.J.). Some of these changes were presented as consensus guidelines initiated by industry groups, such as the Centre for Chemical Process Safety (CCPS), established by the American Institute of Chemical Engineers, the Chemical Manufacturers Association (CMA, now the American Chemistry Council); and the American Petroleum Institute (API). The objective of these changes is to raise the design, operating, and maintenance standards standards of all members m embers of these industries to as high level as is economically possible (Richard W. Prugh, 2006).

Inherent Safety Engineering Process Equipment and Conditions

Process Safety Control Administrative


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ii.

Substitution: Using inherently safer materials or safer processing or production methods

iii.

Isolation: Barricading or distancing to minimize personnel exposure

Design and operating control include (Richard W. Prugh, 2006): i.

Containment: Designing for plant and process integrity

ii.

Attenuation: Using less severe operating conditions of pressures and temperatures

iii.

Consequence Reduction: designing to minimize accidental release rates and quantities

iv.

Simplification: Avoiding complexities in equipment and control systems

v.

Safeguards: a. Passive: Use of explosion vents, rupture disks, relief devices, excess flow valves, and dikes b. Active: Use of alarm and interlock systems, scrubbers, and remote-operated valves

vi.

Risk Minimizations: Arrangements for ventilation, leak-stopping, dump or drown systems, spill control, and toxic and flammable –vapor sensors and alerting systems

8.5.1.2 Administrative Administrative Controls The administrative controls include (Richard W. Prugh, 2006): 1) Operating Procedures; for startup, shut down, response to upsets, and emergencies 2) Maintenance Programs; maintaining program integrity through i nspections and testing 3) Process Hazards Analysis; maintaining program integrity


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Protection may be ensured against toxic chemicals. Individuals can come in contact with materials by ingestion, inhalation, skin irritation, skin absorption and subcutaneous injection (National Safety Council, 1988). However effects of acute and chronic exposures vary with chemicals and their concentrations. Contaminants are physiologically classified (Richard W. Prugh, 2006) as: i.

Irritants; corrosive or vesicant, i.e. cause blisters, and may inflame moist or mucous surfaces. Example: Ammonia, Acids, Alkalis, Bromine, Chlorine etc

ii.

Asphyxiants; prevent blood from transporting oxygen to tissues thus respiratory paralysis. Example: Hydrogen Sulfide

iii.

Anesthetics and Narcotics; depressant action resulting in loose of consciousness without seriously affecting systemic processes. Example: Acetylenic Hydrocarbons

iv.

Systematic Poisons; cause organic injury to one or more of the visceral organs. Example: Benzene, Phenols, Lead, Mercury etc

v.

Particulate Matter; effects varied from minute allergy to cancer. Example: Silica, Asbestos

vi.

Carcinogens; cause cancer and have been declared by several authorities. Example: Nitrogen Mustard

8.5.2 Personal Protection Equipment Industry provides personal protection equipment to its members working in risky areas. The material and kit varies with job description and task-type.


(a)

(c)

(b)

(d)

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F IGURE 7 I NTERNEE P ERSONAL P ROTECTIVE E QUIPMENT (PPE)

(a) Safety Shoes

(b) Hard Hat

(c) Half Respiration Mask

(d) Safety Glasses

8.5.3 Design of Facilities Plant Erection is multi stage process accomplished after millions of considerations and planning procedures. Safety is the first concern of planning team. Several aspects are many times considered and reconsidered for designing the facilities of a plant.

8.5.3.1 Plant Site and Layout The choice of the site of a plant is made after consideration of several factors. Important of


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Operations having potential for fire and explosion are segregated from non hazardous operations, such as offices, cafeterias, laboratories, maintenance shops, and warehouses, to minimize evacuation hazards and victim toll in a fire or explosion incident. When administrative facilities are located on the periphery of the plant, visitors are less likely to be exposed to operational dangers. Vehicles loading facilities are adequately separated from other operating areas as well. Adequate roadways are surrounded every process unit and principal building, for access of maintenance and construction vehicles and fire -protection equipment. (Richard W. Prugh, 2006). FFC MM plant site map is attached in Appendix I. Plant security is an important factor in planning the sites for operating equipment, storage tanks, railcar holding locations, truck operations vehicle parking l ocations and office buildings. Access to all parts of a plant, including i ncluding office building and operating units could be strictly controlled, with fences, card-access or guard-controlled gates, photo-ID badges, frequent patrols of all areas of the plant, and closed circuit television coverage of infrequently occupied areas. (Richard W. Prugh, 2006) Plant designing in accomplished in such a way that interference or deliberate mis-operation may not result in a catastrophe. Ability to interact with computer computer systems within the plant, from outside the plant, could be prohibited or tightly l imited to essential personnel, with a well devised and secure system of pathways. At FFC MM, internet access is restricted to management level employees only, as a safety measure.

8.5.3.2 Utilities


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7. Radiography Work Permit; radiation exposure is expected 8. Vessel Entry Work Permit; vessel or tanks are to be repaired These permits ensure safety of both plant and personnel. Electrical installations and work are done in accordance with National Electrical Code (NEC) for the type of hazard and degree of process containment. T ABLE 4 N ATIONAL E LECTRICAL C OD E , NE C (N ATIONAL F IR E P ROTECTION A SSOCIATION , 2002)

Type Of Hazard

Class I: flammable gas and vapor Class II: organic, metallic, or conductive dusts

Degree of Process Containment

Division I Open

Division II Closed

Class III: combustible fibers

It is more economical to prevent explosive atmospheres in rooms than to provide explosion electrical equipment. Such areas can be reduced when reliable ventilation is provided. Personnel are also avoided to work in such areas. If atmosphere cannot be avoided through control of flammable gases or vapors or combustible dusts, access to the area is limited and the area segregated by walls or other barriers, with special exhaust ventilation. Electrical equipment on open, outdoor structures more than 8 m (25 ft) above ground usually is considered free from exposure to more than temporary, local flammable mixtures near leaks (API, 1987).

8.5.3.2.2 Water


8.5.4 Operation of Facilities Plant operation could be divided (Richard W. Prugh, 2006) into following types: 1. Start-Up; starting up the plant after erection or plant shutdown 2. Normal Operation; routine work flow of plant 3. Shut down; complete plant shutdown for annual repair work 4. Maintenance; repair or replacement of any plant equipment 5. Safe Work Practices; methods for secure and efficient work like tagging of equipment, sign boards, work permits etc

Plant Operation

Start-Up

Normal Operation

Shutdown

F IGURE 8 T YPES

OF

Maintenance

Safe Work Practice

P LANT O PERATION

8.5.5 Human Resource Management 8.5.5.1 Personnel Selection and Training Abilities of operator and workers are closely related with the plant safe operation. Personnel must be both physically and mentally sane and sound. Selection of personnel for task specific

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8.5.5.2 Medical Programs Large chemical plants have at least one full time physician who works a t the plant. Routine check-ups and free medical packages are often included along with basic salary and other provisions. At FFC MM, a medical centre and pharmacy (located at township) offers management and staff, an immediate service.

8.5.6

Disaster Planning

Plant managers usually recognize the possibility of natural and industrial emergencies and formulate a plan of action in case of disaster. The well documented is well circulated and explanatory to all personnel critical to implementation. A checklist for total emergency planning and guide map in such situations are developed. In all emergency situations, the fire services, the safety staff, and the medical organization are of paramount importance importance for the conservation of life and property (NSC, 1988). These plans are so formulated to mobilize the off-duty personnel and to bring in outside help for assistance if needed. At FFC MM, guidelines in case of ammonia release and fire fighting and safety information is well communicated through brochures, circulars, notices and booklets booklets (FFC Safety Section, 2004) to both plant personnel and township residents.

8.5.6.1 Fire Fighting Fire is man’s best friend and worst enemy. Fire Safety, at its most basic, is based upon the principle of keeping fuel sources and ignition sources separate. Three things must be present at


Fires are classified according to the type of f uel that is burning. Use of wrong type of fire extinguisher on the wrong class of fire, you might make matters worse. Fire classification is given in the table below: T ABLE 5 C LASSIFICATION OF F IR E (OSU, 2005)

Fire Class A

Fuel Source Solid Combustibles

Examples Wood, Paper, Cloth, Trash, Plastics

Class B

Flammable Liquids and Gases

Gasoline, Oil, Grease, Acetone

Class C Class D

Electrical Fires Combustible Metals

Energized Electrical Equipment Potassium, Sodium, Aluminum, Magnesium

Extinguishment or control of fire is essential. Exposure of personnel to thermal-radiation hazards must be minimized and property protected. Extinguishing fire requires cooling below the flashpoint, removing the oxidant, or reducing the fuel concentration below the lower flammability limits (Richard W. Prugh, 2006). Most fire extinguishers have a pictograph label telling which types of fire the extinguisher is designed to fight.

Class A

Class B

Class C

F IGURE 10 F IR E E XTINGUISHER L ABELS

Class D

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Dry-chemicals like bicarbonates or ammonium phosphate provide a coating that makes the material suitable for use on fire involving solid combustibles like rubber tires, wood and paper (Richard W. Prugh, 2006)

8.5.6.2 Types of Fire Extinguishers Fire extinguishers are designed to fight different classes of fire. Water (APW) Fire Extinguishers: APW’s extinguish fire by taking away the “heat” element of the Fire Triangle. These are designed for Class A fires i.e. fires that have their origin from wood, paper, cloth. Using water on a flammable liquid fire could cause the fire to spread. Using water on an electrical fire increases the risk of electrocution. If there is no choice but to use an APW on an electrical fire, the electrical equipment should be un-plugged or de-energized. Carbon Dioxide Fire Extinguishers: Carbon dioxide dioxide cylinders are red and black. They range in size from 5 lbs to 100 lbs or larger. larger. On larger sizes, the horn horn will be at the end of a long, flexible hose. The pressure in an extinguisher is so great, carbon dioxide will be in liquid form may shoot out of the horn. These are designed for Class B and C (Flammable Liquids and Electrical Sources) fires only and are placed in laboratories, mechanical mechanical rooms, kitchens, and flammable liquid storage areas. Carbon dioxide is a non-flammable gas that takes away the oxygen element of the fire triangle. Without oxygen, there is no fire. Carbon dioxide is very cold as it comes out of the extinguisher, so it cools the fuel as well. Extinguisher may be ineffective in extinguishing a Class A fire


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9 Safety Section FFC believes in “safety first”. FFC Management is committed to cause of safety and believes that i t is everyone's responsibly. The objective is to i mprove the working culture through effective safety program. Zero lost work days are the target (FFC Safety Section, 2010). Details are enclosed in Appendix II (FFC MM Plant Safety Policy) and Appendix III (FFC Plant Safety Rules and Regulation). Recognition for safe work is arranged in collaboration with NSC, USA. Till July 2010, 8.3 million safe hour operations have been carried out, i.e. no Lost Ti me Accident (LTA) has taken place since last 8.3 million hours. FFC MM has also received IMS 2009 certification for safe working other than ISO 9001, ISO 14001 and ISO 18001. Safety Section of FFC MM performs various functions and activities for running an effective safety program through the following hierarchy of section: Section Head (01)


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Managing Safety Program Main object is to plan, organize, budget, and track execution of activities to achieve safety objectives of our plant laid down in FFC MM Safety Policy (Appendix II). Through prudent planning and effective resource management safety section cater for all the needs of personal and process safety.

Motivation Safety section is committed to achieve excellence in the field of safety. All projects related to safety are given top priority and good safety and housekeeping standards standards are appreciated through token rewards. This include slogan of the year, best housekeeping award, safe man of the year award and safe men hours award.

Hazard Recognition It ensures the identification of conditions or actions that may cause injury, illness or property damage, is a routine activity carried out at all levels in plant areas. Plant safety committees are formed all hazards of the plant are highlighted and engineering solution are evolved. Safety section also carries out routine audits of the plant and points out hazards to


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Regulatory Compliance It ensures that mandatory plant rules and regulations (Appendix II) and International Safety standards are satisfied.

Health Hazard Control It conducts audit and control hazards such as noise, chemical or radiation exposure.

Hazardous Material Management It creates awareness that dangerous chemicals and other products are procured, stored and disposed of in ways that prevent exposure or fire. Display of MSDS in areas to increase consciousness, are ensured.

Training Safety Section provides management and employees with the information and skills necessary to recognize hazards and perform their job effectively and safely. All safety inspectors are trained as fire fighters and work permit procedure auditors. Section also maintains training record of all manpower.


25

Evaluating It evaluates the effectiveness of our program through various indices like accident/ incident rate, use of personal protective equipment, quality of job safety. It also considers reporting of near miss as an effective system to avoid occurrence of a real risk.

9.2 Safety Training FFC ensures safe work environment by providing safety training to all personnel on plant. As per the company policy all news personnel on plant receive safety training prior taking charge of their responsibilities. Safety training was provided to the group comprised of author and two other internee engineers by Mr. Mushtaq Ahmed (Safety Sub-Engineer) on July 1, 2010 at Safety Section, FFC MM. Training introduced with the plant safety policy and rules and regulations, while functioning of safety section was also briefed. T ABLE 6 S AFETY D ESCRIPTION

AS SET BY

S AFETY S ECTION, FF C MM

S

A

F

E

T

Y

Search

Analyze situation

Find

Eliminate reasons

Tell

You

others

are safe

for hazard

causes


26

FIRE ALARM

10

10 05

10

10 05

05

10 05

10 05

10 05

10 05

SECONDS

DISASTER (HE AVY AMMONIA LEAKAGE)

30

10

30

10

30

10

30

30 10

10

30

10

30

10

30

SECONDS

EVACUATION EV ACUATION ALARA M

Repeated above disastar alarm END OF EMERGENCY

90 SECONDS

F IGURE 11 E MERGENCY S IREN S EQUENCE (FFC S AFETY S ECTION, 2004)

The plant produces ammonia as the raw material for urea production. Ammonia as a hazardous gas always has a probability of release in case of leakage or disoperation. This may result in ammonia disaster leading to a catastrophe if not avoided or duly responded. Safety is therefore an important consideration prior to working on plant.

9.2.2 Use of Personal Protective Equipment The Personal Protective Equipment provided to internees included safety shoes, hard hat, half face mask and safety glasses. The training gave an idea to author of when and how to use the


27

Fire is the most common form of disaster for any industry but could be dealt, if well prepared. Fire erupts due to unsafe work, and could be avoided i f well planned and followed. In order to avoid any unpleasant accident, personnel are trained for fire fighting. Internees were told taught to use the fire extinguishers for self safety. Strategies in fire incidents and emergency response have been both notified and published (FFC Safety Section, 2004) by Safety Section.

F IGURE 12 E MERGENCY R ESPONSE (FFC S AFETY S ECTION, 2004)

Using fire extinguisher e xtinguisher was introduced synonymously with an acronym PASS; pull, aim, squeeze


28

2. Call 3222 Safety Section or 3234 Shift coordinator and activate the building fire alarm. The fire alarm will notify the fire department and other building occupants and shut off the air handling system to prevent the spread of smoke. Before using a fire extinguisher, it was suggested to know what is burning. burning. Else, using the extinguisher would not be a wise decision as it could result in a bigger problem. Even if an ABC fire extinguisher is available, there is always a possibility that fire may explode or produce toxic fumes. Fire extinguishers are used to control fire in initial stages (OSU, 2005). If fire is continuously increasing from the source point, it is wise to immediately evacuate the building.

9.2.4 Ammonia Disaster Leakage or unwanted release of ammonia from plant has been termed as Ammonia Disaster. Ammonia being a hazardous gas chokes respiration process resulting in death. Therefore, for safe escape, plant personnel and township residents are trained for plan of action in case of ammonia disaster. All offices, buildings and homes are constructed with an ammonia shelter, in case of emergency. Shelter has no windows and only single door which can be sealed in case of ammonia release. Personnel and families can remain save in shelter until safety announcement is made.


29

10 Production Unit Production unit of an industry manages product production in field in coordination with process unit (which does the desk job for same). The sole responsibility of the unit is to ensure maximum production through overcoming the problems and issue coming up on daily routine on plant. The unit manages process parameters like temperature, pressure, flow rate etc to achieve production targets, while guaranteeing the safety of personnel and plant. The plant is monitored / controlled through a controlling centre (CCR at FFC MM) where shift engineers work under the supervision of a coordination engineer and achieve the set goals. At FFC MM, production unit works under a Production Manager and is sub-divided into four sub-units, as per their working goals. These include: 1. Utilities Unit; provides utilities like instrument i nstrument air, cooling water, electricity to other units 2. Ammonia Unit; provides raw materials i.e. ammonia and carbon dioxide for urea section 3. Urea Unit; produces the product urea (trade name: Sona Urea) 4. Bagging and Shipment Unit; bags urea and dispatch it to consumer market




30

To provide desired quantity and quality of certain utilities to the ammonia and urea units for smooth functioning. These utilities include electricity, cooling water, instrument air, fuel gas and steam network.

Water, air and natural gas are the basic utility util ity raw materials, which are processed and improved in order to meet the plants’ criterion of quality and ensure a longe r life and safety of

equipment. T ABLE 9 P LANT U TILITIES D IVISION

Water Cooling water Steam Utility / service water Drinking water

Air Instrument air Utility / service air Process air

Natural gas Process stream Fuel stream

Utilities unit is a pre-requisite for other units because their smooth running depends upon the utilities supplied by it. In case of utility failure plant has to face an emergency shutdown. Major sub-divisions of utility section are: 

Water Treatment



Cooling Tower System


31

The section is controlled through the PLC based system in WTCR (Water Treatment Control Room) located next to installations in area 09. WTCR also manages the preparation of different chemicals in desired qualities, needed for water treatment. These include ammonium hydroxide, chlorinated water, ferrous sulfate, lime solution, sodium hydroxide, sulfuric acid etc. At FFC MM, sources of water are Masuwah canal flowing from Guddu Barrage and tube wells. Canal water has the main usage, where as tube wells are used in case of canal supply is suspended. Water from canal is collected in a collection pit under gravity or pumped (when canal is flowing below routine level) by four motor driven centrifugal pumps called Canal Bank Pumps (MP-950 G/H/I/J). A mesh is used to prevent litter and garbage from coming inside the pit. Water is 3

pumped to clarifier (ME-920 also called Italfloc) at a flow rate of 250 m /hr through six motor driven Canal Bank Pumps (MP-950 A/B/C/D/E/F), connected in series. In case of tube well (thirty one units installed on the other side of N5) service, motor driven MP-950 D/E/F pumps are used pump water from tube wells to collection pit. Water treatment is further sub divided into:


32

The mixture enters the reaction zone of clarifier (ME-920) and is mixed with recycled sludge and suspension of of lime slurry. Mixing and recycling recycling are ensured by a dual dual stirrer (MM-920 A) moving at 2 – 6 rpm. Through high activity of particles in reaction zone, suspended particles are held together to make flocs and settle down to the bottom of clarifier. A bottom scrapper (MM920 B) moving at 0.06 rpm prevents building up of deposits and scales by conveying the sludge towards the extraction cone, where it is withdrawn by gravity and recycled in some quantity to the reaction zone. The main flow from the reaction zone to the upper portion passes to the upper flocculation area and finally flows in to the outer clarification zone. During the final passage, it goes through the bed of pre-formed pre -formed sludge (also called sludge blanket), where it deposits both impurities and suspended particles. Clarifier has a residence time of approximately 95 minutes and is equipped with several sampling points for testing the concentration of the sludge at different levels. Clarifier i s set to maintain a particular sludge bed height at bottom, on exceeding, the blow down will automatically start. Chemical Dosage to a clarifier could be divided into three types: coagulants (ferrous sulfate and chlorine), flocculants (polyelectrolyte) and softeners (lime). Sometimes, natural iron present in raw water is used to supply the part of coagulant. When iron salts are used, the best flocs are formed when the pH value is between 10.2 to 10.4. Therefore, if dissolved iron content exceeds

Internship ’10 Report (Production Unit) Polyelectrolyte Lime

0.3 5

33

0.6 kg/hr 675 kg/hrs

Following (M. Yaqoob Ch., 1987) modifications are achieved to the quality of water in a clarifier: 

Turbidity reduction



Color and organic matter reduction



Lime softening o

Calcium reduction

o

Magnesium reduction



Alkalinity reduction



Partial demineralization



Free carbon dioxide reduction (up to zero level)



Iron reduction (up to zero level)



Silica reduction

Clarified water is collected into radial channels, flowing in to annular channels outside the basin and finally into the feeding channels of the collection basin ME-926. The basin with a capacity 3

of 800 m , corresponds to an average retention time of 45 minutes at nominal flow, to shadow 3

the effects of excess chlorine dosage. Through pumps P-926 (capacity 500 m /hr) a certain


34

encounters the suspended matter in water with sand bed in filters which finally becomes clogged and demands periodic regeneration after particular operational time. 3

Clarified water at 70 m /hr flow rate is delivered to battery of four gravel filters (V-920 A/B/C/D) connected in parallel. At odds, flow rate is regulated by a valve LIC-02-V actuated through the level controller 09-LIC-2 located into the fi ltered water storage tank T-920. Thus the flow rate of water to the filter is proportional to actual requirement of users i.e. treatment section. Filters are filled with 18 tons of light grey bright quartz sand particles with 97% silica. During filtration, suspended matters contained in the water are retained inside the filtering bed which becomes clogged and the pressure increases to a maximum value (approx 1.0). Clogging however doesn’t depend only upon the total quantity of retained particles, but also upon the

time of operation. At a time, two filters are in operation and two are on regeneration. Back washing water collected in back-washing pit is sent to clarifier after mud settling, to reduce 3

water losses. Filter water is stored in storage tank 09-T-920 having capacity 600 m /hrs.

10.1.1.2Demin 10.1.1.2 Demin Lines The purpose of the demin lines is: 

To remove permanent hardness producing ions from the filtered water

Internship ’10 Report (Production Unit) T ABLE 12 M INERAL I ONS

Cations Aluminum Barium Calcium Magnesium Potassium Sodium

Anions Bicarbonate Chloride Sulfate Nitrite

IN

W ATER

Other Silica Carbon dioxide

Process Condensate

Activated Carbon Filters V-980 A/B/C

Filtered Water Tank T-920

Deionized Water Tank

Mixed Beds

T - 940

V-944 A/B/C

35


36

Filtered water stored in tank (T-920) is i s fed by the pump P-925 A/B/C to the cation exchangers V-940 A/B and percolating on the resin bed, exchanges ions like calcium, magnesium, sodium, potassium with hydrogen ion. Decationized water is then finely dispersed through spraying nozzles of the atmospheric degasifier V-941 and percolates as a very thin layer along the surfaces of rashing ring arranged on two consecutive layers meeting in counter current with the air flow released by fan K-941. The air current maintains partial pressure of carbon dioxide at very low levels thus allowing an easier escape from liquid phase in to the gaseous phase and its stripping by the air of the fan. The residual carbon dioxide valve in water coming out from tower should not be more than 10 ppm. A hydraulic guard set on the water outlet from the tower prevents any air dispersion from blower, thus forcing the air to flow upward and cross the layer of filling rings in such a way that makes large turbulence in the gaseous mass thus involving the whole mass in transfer mechanism. The purpose of filling rings in tower is to increase the gas / liquid contact area, thus making water to percolate in the form of fil m. By this way optional conditions for me removal of dissolved carbon dioxide are obtained, because the efficiency is directly proportional to the


37

T-901. Regeneration of vessels is done by 2 % and 4 % of sulfuric acid (strong cationic resin), 4 % sodium hydroxide solution (strong and weak anionic resins). Water treatment plant has been designed mainly for tube well water and keeping in consideration the canal water. Regeneration of cation exchanger in counter current according to econex system is definitely needed because tube well water has sodium content as high as 85%. To avoid any movement in resin bed during counter current phase, the resin is held fixed by filling the free space above the resin with polyethylene beads. This material is called ECONEX and is completely inert from chemical point of view.

10.1.2 Cooling Tower System (Area 08) The section cools the hot water coming from exchangers installed at different location of plant site through evaporation in induced draft cross flow cooling tower cells. The tower is splash-type cross flow and induced air cooling. It consists of 8 cells separated by gates with a common water collection basin. Each cell comprises of six louvers and space between the consecutive louvers is filled with 12 layers of poly propylene filling. A cell comprise of three portions with a fan on the top. The fan is located at the centre of the cell and is motor


38

3

efficient cooling. Evaporation causes cooling and cooled water is collected in 6900 m basin, from where it returns to exchanger for heat duty. Cooling of water is achieved by atmospheric air drawn by the atmospheric air, drawn by the fans on the top of each cell. Air contacts the sides of cooling tower and passes between the packing and is drawn up by fan. An efficient system of drift eliminators in air passage eliminates the entrained water from air (cooling tower drift) and reduces water losses. T ABLE 13 C OOLING T OWER D ESIGN D AT A

Type Flow rate Basin capacity Number of cells Ambient air temperature Cold water inlet temperature Cold water outlet temperature Wet bulb Dry bulb Heat load Air relative humidity Make up Blow down Drift losses Evaporative losses

Induced Draft / Cross Flow 3 31000 m /h 3 6900 m 8+2 7°C 43 °C 32°C 28°C 47.8°C 341 G cal/h 80% 3 803 m /h 3 158 m /h 3 0.1 % (31 m /h) 3 2 % (614 /h)


39

Several microorganisms like algae, fungi and bacteria can develop causing blockage of thin tubes, bacterial inhibitors that are poisonous to mirco-organisms are used to avoid them. Corrosion is controlled through addition of corrosion inhibitors; zinc, phosphates, polyphosphates, ortho-phosphates etc. Water in cooling tower is also treated and fi ltered to remove impurities, i mpurities, to maintain the pH level, to avoid rusting, and corrosion and biological micro organisms. Several chemical like Zinc Phosphate (corrosion inhibitor), sulfuric acid (maintains pH) etc are dozed to keep water quality constant. A slime measuring unit is also employed to measure the quantity of slime (waste of micro-organisms) in water.

10.1.3 Waste Water Disposal (Area 16) The section ensures that the effluent disposal from plant is within safety limits and regulations set by EPA or NEQS. Waste water is disposed to two places: 

Masuwah Canal; when parameters are in permissible range



Evaporation ponds; when parameter are out from the set values

Effluents from various plants are in general collected in a common pit and treated before

Internship ’10 Report (Production Unit) Zinc Sulfate Chromium Conductivity

40

5.0 ppm 600 ppm 1.0 ppm 2 2500 micro S/cm 3

Waste water from all plant sites at a flow rate of 250 – 300 m /h is collected in pit A, where it is neutralized with sulfuric acid. The dosing of sulfuric acid is controlled by the pH transmitter controller. It controls the pH between 6.5 -8.5. A stirrer in the pit helps the neutralization reaction. The neutralized water overflows in the next pit B. Water from the settling ponds (if any) also mixes up with neutralized water in pit B. Waste water is pumped to canal by means of P-1603-A/B. In case of effluent not being within the permissible range, waste is directed to the evaporation pond, to save canal from polluting. Waste water is sampled at an interval of every 4 hour for lab testing to verify the chemical dosage for neutralization.

10.1.4 Instrument Air Compression (Area 10) The section provides compressed air for instrument and utilities to all units of ammonia and urea plant. Instrument air make possible the functioning of pneumatic valves installed over multiple locations on plant. The area is of extreme importance because in case of its failure,


41

separator to remove the condensate water produced as a result of cooling. Cooling i s automatically operated through SDV, while the pressure is controlled by PCVs. The output is provided with selector having positions: auto, 50% manual, 100 manual. Switching selector to 50% manual makes half of the suction valves idle, reducing compressor capacity to 50 %. At 100% manual, all valves are in service and machine is operated at 100 % capacity. 3

The air receiver V-1001 has a capacity of 100 Nm . Air supply from K-1001/1002 is stored at 2

50°C and 8 kg/cm . Receiver provides the compressed air to utility air network and air drying 2

station for instrument air supply. PCV protects vessel by blowing at 9 kg/cm . The compressed air from V-1001 is sent to air drying section through a cooler E-1001 and condensate separator V-1002. The air cools down to 37°C while passing through the final cooler E-1001 and condensate is separated in V-1002. The compressed air is then fed to air dryers MD1001 A/B (one in service and other on regeneration), where in moisture is absorbed in activated alumina. Dried air is finally passed through air fi lters ME-1001 A/B, where sub-micron particles are removed from air. The resulting dry and clean instrument air is supplied to plant at 7 2

kg/cm .


42

consists of 18 elements as filter media. Process gas is then fed to steam reformer F-201 at 46 kg/cm2. Fuel gas to boilers and furnaces is supplied at 5.6 kg/cm 2. Natural gas to township is supplies at 2.5 kg/cm 2 after adding odorizing agent tetra thiophene (THT) to it. 10.1.6 Auxiliary 10.1.6 Auxiliary Boilers (Area 06) Boilers are designed to produce steam as dry as possible at high temperature and pressure. Steam is necessary for every plant which is used to move turbines. These turbines are used to generate electricity, to compress the air in compressors, in cracking of natural gas and in some heating processes. Boiler installed in area have a capacity of 110 ton/hr. DM water is pre-heated and de-aerated to be converted to BFW. DM water is degasified i.e. DO and carbon dioxide are removed from water in a deaer ator V-603. At BP, almost all dissolved gases are practically removed. Water is heated with steam to increase the temperature and consequently remove the dissolved gases. The surface area of water is increased by spraying it in the form of jets. This increases the degasification reaction. DM water after being pre-heated in ammonia section (area 02) enters the top of the deaerator and is collected in a jacket. The jacket is fitted with jet sprayers, which spray water against the


DM Water Tank T-901

BFW Preheater

Deaerator

Accumulator Accumulator

Economiser Economiser

Steam Drum

Boiler

Super heater

43

Turbine

F IGURE 15 B OILER N ETWORK

10.1.7 Power Generation (Area 07) Electric Power is generated through turbo generators (TG), which are the turbine driven for the production of electricity. There are the major source of electricity for all the plant having a capacity of 16 Mega Watts (2 generators each has capacity 8 Mega Watts). An emergency stand by diesel generators (EDG) having a capacity of 1.5 Mega watts, is also installed.


44

RPM. So a gear box in installed to reduce the RPM. And other imported thing in the Turbo Generators is Governors. These are just like a control valve. That controls the steam quantity depending upon the load of generator. EDG ME-702 is a V-shaped four stroke; single acting engines with 16 cylinders arranged eight on each side of V-shape. It works on diesel cycle, coupled with electric generator capable of producing 1900 K V A electricity.


45

10.2 Ammonia 10.2 Ammonia Unit The core purpose of ammonia unit is to provide the raw materials for urea unit. They The y are: 

Liquid ammonia at – 4 °C



Carbon dioxide gas (by-product)

For producing these urea raw materials, unit needs a mixture of hydrogen and nitrogen gas in ration 3:1. A limited degree of inert gases like argon and methane are also present. Source for hydrogen are generally hydrocarbons in the form of natural gas. The source for nitrogen is atmospheric air, both cheap and abundantly available. The following processes take place in different sections of unit: 

Desulfurization section; removes sulfur content of natural gas



Reforming section



o

Primary reformer; cracks natural gas to give hydrogen

o

Secondary reformer; eliminates oxygen from air leaving nitrogen

Gas purification section o

Shift Conversion; converts carbon monoxide to carbon dioxide


46

Natural gas coming from Maripur gas field through Natural Gas Station (Area 15) has compositions (Molecular Mass 20.91): T ABLE 15 N ATURAL G AS C OMPOSITION

H2 N2 CO2 CH4 C2H6 3

0.1 % 19.5 % 9% 71 % 0.2 % 2

Natural gas at a flow rate of 36472 Nm /h at 30 kg/cm and at 38°C is compressed in natural gas 2

compressor K-411 to 40 kg/cm and 72°C and mixed with a recycled synthesis (short: syn) gas stream and the mixture is then pre-heated to 310°C in process gas pre-heater E-204 B and then to 400°C in process gas pre-heater E-204 A (both in convection zone of primary reformer). Despite the fact that key reaction of conversion of inorganic sulfur to z inc sulfide is possible at ambient temperature conditions, stream is pre heated to: 

Convert organic sulfur to inorganic sulfur (350°C)



Promote reaction of absorption bed with carbonyl sulfide (310°C) ZnO + COS → ZnS + CO2 (II)


47

3

Each vessel contains 21 m of Topsoe sulfur absorption catalyst HTZ-3 (specially prepared Zinc Oxide) in two beds with a bed height of 2.15 m each. The endothermic reaction reduces the sulfur content according to the following rate of reaction: -6

-9

KI = 2.5 x 10 at 380°C

KII = 4 x 10 at 380°C

The rate of reaction increases with increase in temperature: -6

-9

KI = 4 x 10 at 400°C

KII = 7 x 10 at 400°C

Fresh or sulfide catalyst neither reacts with hydrogen nor oxygen at any practical temperature. HTZ-3 has several advantages in comparison with other sulfur absorbents like activated iron mass. The absorption capacity (expressed in weight of sulfur absorbed per volume of absorbent) is more than twice as high for HTZ-3 as far iron oxide. Methanation of gas containing carbon mono or dioxides will not occur using zinc oxide catalyst. The catalyst does not become pyrophoric during operation and therefore its disposal presents no problems. The operation 2

temperature could vary from ambient to 50 kg/cm (700psig) or even higher. The normal operating temperature ranges from 350°C to 400°C. Absorption capacity of catalyst is 39 kg sulfur per 100 kg of catalyst or 545 kg of sulfur per cubic meter or reactor volume.


48

CH4 + 2H2O ↔ CO2 + 4 H2 (600°C) CO2 + H2 ↔ CO + H2O It is desired to keep the methane content of syn gas as low as possible to keep the inert level minimum. Methane content is governed by reforming reaction which is promoted by high temperature, low pressure and more steam. On the other hand, high pressure reforming can give considerable savings in power consumption for syn gas compression and equipment size could be reduced as well. An economic compromise has been achieved by keeping operating 2

pressure at 35 kg/cm . The third reaction consumes important hydrogen and therefore is minimized with excess steam to carbon ratio is increased to 3.75:1.

10.2.2.1Primary 10.2.2.1 Primary Reformer Primary reformer has a total of 288 28 8 reforming tubes installed in two radiant chambers with a common flue gas channel and 648 burners burners on side walls. The side-fired tubular reformer offers: 

Uniform and higher heat flux



Fewer tubes and longer tube life



No risk of flame impingement Safer and more reliable operation

Internship ’10 Report (Production Unit) T ABLE 17 G AS C OMPOSITIONS

H2 N2 CO CO2 CH4

AFTER

49

P RIMARY R EFORMER F-201

65.5 7.14 10.13 11.44 5.77

It is possible that during operation, carbon might deposit on the catalyst bed. This would lead to an increase in pressure drop for outside deposition and reduction in activity and mechanical strength of catalyst for inside deposition. Carbon formation is avoided by maintaining equilibrium for each reaction step. Other reasoning for carbon formation includes: 

Catalyst poisoning by sulfur; reducing activity and increasing carbon deposition



High contents of olefins, aromatics or naphthenes in hydrocarbon feed



Low steam to carbon ratio

10.2.2.2 Secondary Reformer Secondary Reformer R-203 is used to separate nitrogen from air by burning the oxygen with it 3

and reforming the remaining methane. 35 m of RKS-2 catalyst in the form of ceramic rings placed on the lower portion of reformer. The combustion of air will give high gas temperature at the top of catalyst bed. The reaction re action mixture contacts with catalyst catalyst at the temperature about

Internship ’10 Report (Production Unit) T ABLE 18 G AS C OMPOSITIONS

H2 N2 CO CO2 Ar CH4

AFTER

50

S ECONDARY R EFORMER R-203

55.93 22.15 12.14 9.02 0.20 0.30

Gas from secondary reformer is cooled in a waste heat boiler E-208, to 380°C. As the stream contains considerable amount of carbon mono and dioxides, there is a probability of carbon formation, when the gas is cooled. 2CO → CO2 + C (soot) The reaction is only possible with the range of 650°C – 720°C because of equilibrium conditions. At temperatures below 650°C, the rate of reaction is too slow to have any practical importance. Therefore, a waste heat boiler is employed to provide a rapid cooling. The boiler rapidly decreases the temperature by converting water into high pressure steam, without a contact between process gas and hot surface.

10.2.3 Gas Purification Section (Area 03) The section prepares a syn gas containing hydrogen and nitrogen in ratio of 3:1 by purification.


51

Inert levels in ammonia synthesis loop are controlled via purging of inerts to keep the level low and obtain higher production.

Reforming Section

HTS Convertor

LTS Convertor

(Area 02)

R-204

R-205

Benfield Ammonia Synthesis Section (Area 05)

Methanator R-311

Benfield Absorber C-302

Regenerator

F IGURE 16 G AS P URIFICATION S ECTION (A RE A 03 )

10.2.3.1 Shift Conversion Shift conversion of carbon monoxide to carbon dioxide is an equilibrium reaction with low temperature and more water supporting the forward move. However, higher temperature will give a higher reaction rate. More water can apparently give a lower reaction rate due to bigger total volume giving a shorter contact time. An optimum temperature is therefore needed to give the best conversion. Keeping in view vi ew the activity and quantity, conversion is performed in two steps: 

High temperature shift (HTS); to increase the rate of reaction


52

Gas stream from the secondary reformer enters the HTS convertor R -204 after being cooled by waste heat boiler. The main part of reaction takes place here causing a temperature increase of 59°C. The outlet stream temperature is 435°C. The gas from HTS convertor is then cooled in trim heater E-205, HP waste boiler E-210 and BFW pre-heater E-211 to 220°C before being sent to LTS convertor. T ABLE 19 G AS C OMPOSITIONS

H2 N2 CO CO2 Ar CH4

10.2.3.1.2

AFTER

HT S C ONVERTOR R-204

59.66 20.28 2.87 16.73 0.19 0.127

LT S – Convertor

The LTS convertor R-205 consists of specially prepared zinc and chromium oxides catalyst with much higher activity and therefore is used at lower temperatures of 220 °C – 240°C. Catalyst 3

loses its activity if temperature is higher than 250°C – 270°C. 85 m of LSK catalyst is distributed on two beds each 2.8 m high. The catalyst which is in the form of small pellets is sensitive to sulfur, chlorides and gaseous silicon compounds. Activity is diminished by 0.2 wt % sulfur and 0.1 wt % chlorine. Catalyst is activated through reduction with natural gas at 150°C

200°C


53

converted in to bicarbonate and 3 % di-ethanolamine (DEA) as an activator. The solution is kept hot to increase the absorption rate and maintain bicarbonate content in solution. High temperature is also an advantage for regeneration which requires the same temperature. Both in absorber and in De-absorber the Demister pad are use to avoid the Benfield solution particles goes with the gas stream. Section has a Benfield Absorber C-302 and a Benfield Regenerator C-301. The absorber C-302 contains four beds of steel pall rings arranged in four beds in a column. column. The two upper beds 3

with bed height 7.7 m and dia 2.5 m contains a total of 75 m of 1.5’’ rings. Th e lower two beds 3

same bed height but dia 3.50 m contains a total of 148 m of 2’’ rings. The 4.5 m dia 3

regenerator C-301 contains four beds of 450 m 2’’ pall rings with a total height of 28.20 m. The gas from LTS convertor R-205 is passed through the LP steam boiler E-301 where water in the stream is condensed, while the temperature is dropped to 160 °C. Passing through the separator V-305, process condensate is withdrawn and gas i s further cooled through passage from Benfield re-boiler E-302 and BFW pre-heater E-304 to minimize the temperature to 110°C 2

and 27.7 kg/cm . Separator V-304 removes the further traces. Gas is then passed to the bottom of Benfield absorber C-302, where it flows counter-currently


54

K2CO3 + CO + H2O ↔ 2 KHCO3 The reversible reaction enables the regeneration of potash solution and recovery of carbon dioxide by disturbing the equilibrium conditions. The solution is sent to the top of Benfield 2

regenerator C-301, where pressure is reduced to 5 kg/cm to flash the carbon dioxide off. Remaining is removed from the solution by flowing it downwards through the packed tower in 2

a counter-current flow with LP steam at 138°C and 0.5 kg/cm . Regenerated solution from the bottom of the tower is pumped back to absorber through circulation pump P-301. The main part of solution is introduced in the absorber under the upper two beds, while the rest is cooled in LP BHW pre-heater E-307 and split stream cooler E303 to 70°C and introduce top of the absorber. 2

The steam – carbon dioxide mixture from the top at 105°C and 0.5 kg/cm is cooled in BFW pre3

heater E-305 and condenser E-306 before separation in separator V-301. Here 7874 Nm /h 2

carbon dioxide is separated and sent to the urea unit at 45 °C and 0.29 kg/cm , while the condensed steam is through condensate pumps P-302 A/B to sewer. T ABLE 22 C ARBON

DIOXIDE

C OMPOSITION

FROM

B ENFIELD R EGENERATOR C-301


55

catalyst. The reactor reduces the combined carbon mono and dioxides compositions to less than 10 ppm with a temperature rise of 30 °C. 3

Methanator R-3111 contains 30 m of PKR catalyst in the form of spheres in a single bed of 3.1 m height. The catalyst has approximately similar characteristics as reforming catalyst but great activity due to reaction at lower operating temperatures. Process gas stream from the top of the Benfield absorber C-302 passes through separator V-302 to remove the traces of potash solution. Passing through the shell of gas-gas exchanger E-311 and trim heater E-205, its temperature is increased to 320°C and fed to methanator R-311. Methanated gas at 351°C is passed through the tubes of gas-gas exchanger E-311 and final gas cooler E-312, it is fed to a separator V-311; from where it leaves for ammonia synthesis section 2

at 39°C and 25 kg/cm . T ABLE 23 G AS C OMPOSITION

AFTER

H2 N2 Ar CH4

10.2.4 Ammonia 10.2.4 Ammonia Synthesis Section (Area 05)

M ETHANATOR R-311

74.4 % 24.74 % 0.23 % 0.92 %


56

condensation and separation separation of ammonia. The synthesis loop is operated at 380°C – 520°C and 2

270 kg/cm , with promoted iron catalyst containing small amounts of non-reducible oxides. Reaction liberates about 750 kcal/kg ammonia produced, part of which is utilized to pre-heat the HP boiler feed water. The convertor R-501 is a radial type convertor with the gas flowing through the two catalyst 3

beds in a radial direction. It contains a total of 33 m catalyst, distributed in three beds with bed 3

3

3

height 5 m , 10 m and 18 m respectively. Catalyst size decreases downward in beds, increases the catalytic activity of smaller particles. The catalyst is stable i n air below 100 °C, while above 100°C it reacts and spontaneously heat up. The catalyst is activated by reducing the iron oxide surface layer to the free iron, by circulating syn gas. Catalyst activity decreases slowly during normal operation, with a catalyst life of 5 – 8 years. Catalyst life is much influences by process conditions like temperature in the catalyst bed and concentrations of catalyst poisons in syn gas convertor. Lower temperatures temperatures reduce catalyst activity and prolong lifetime. Therefore lowest possible temperatures are maintained observing a stable operation. The catalyst temperature ranges 500°C – 530°C. Compounds like water, carbon monoxide, and carbon dioxide, sulfur or phosphorous compounds compounds are all poisons to the catalyst.


57

Temperature conditions at the reactor inlet are also an important governing factor. At the top of the convertor, where has enters the catalyst layer, a certain minimum temperature of 380°C - 400°C is required to ensure a sufficient reaction rate. If the temperature at the catalyst inlet is below 370°C – 380°C, the reaction rate will become so low that the heat liberated by the convertor and the reaction will quickly quickly extinguish itself, if proper process adjustments are not made properly. The reactor is so designed to increase the temperature of an inlet gas through exchangers up to 400°C, where it enters the first catalyst bed from bottom. As the gas passes through the catalyst bed, the temperature is increased to a maximum temperature at the outlet from the first bed. The temperature here is about 520°C, which is normally the highest in the convertor and is called “The Hot Spot”. The gas from the first bed is quenched with cold gas to 400°C –

420°C before the second bed. After the second bed, the out let temperature is about 500°C. The syn gas from methanator R-311 is i s compressed in synthesis re-circulation compressor K2

431/432 and fed to the synthesis loop at 39°C and 261 kg/cm . As the gas has a maximum carbon mono and dioxide concentration up to 10 ppm and water vapor concentration in order of 330 ppm, depending upon synthesis pressure. Therefore, this large amount of water is


58

introduced between the ammonia chillers E-505 and E-506, so that carbamate remains dissolved in liquid ammonia. The carbon monoxide content of gas does not react with ammonia as dioxide does, neither is it absorbed by the condensing ammonia. The total amount of carbon dioxide is therefore fed to the catalyst, where it is hydrogenated to water and methane. This reduces the activity of the catalyst and hence the monoxide concentrations are kept as low as possible. T ABLE 25 G AS C OMPOSITIONS

OF

C IRCULATING S YNTHESIS G AS B EFORE C ONVERTOR R-501

NH3 H2 N2 Ar CH4

3.60 % 63.31 % 21.09 % 2.44 % 9.56 %

The circulation syn gas separated by ammonia separator V-501 at 0°C is passed through the shell of cold heat exchanger E-504 and compressed; to be fed to the convertor R-501 at 150°C 2

and 269 kg/cm . The gas contains up to 3.6 % of ammonia (function of operating temperature and pressure conditions), which is of importance for the conversion obtained. A low ammonia concentration at convertor inlet gives a high reaction rate and thus a high production capacity. In convertor R-501, only about 25 % of hydrogen and nitrogen (obtained in syn gas at convertor


59

circulating syn gas in the ammonia separator V-501. Make-up gas is introduced between the two chillers. The circulating syn gas contains about 12 % inerts (argon and methane) which do not go any chemical reaction in convertor. As syn gas is recycled, the inerts level is increased until constant addition of inerts with fresh feed is counter-balanced by a constant removal of the same 3

quantity of inert gases from the synthesis loop. At designed conditions, 7437 Nm /h of synthesis gas is constantly purged from the loop after the first ammonia chiller E-505 (inert level is high after the first chiller). However, purge rate is so adjusted to keep the inerts level 12 % in the loop. With catalyst age and decrease in activity, purge should gradually be increased to maintain the constant production. Dissolved inerts flash off in the let-down vessel V-502, where 2

pressure is decreased to 25 kg/cm . Ammonia liquid stream from ammonia separator V-501 goes to a let-down vessel V-502 to for further removal of gaseous contents, from where it is further directed to ammonia spheres S501 and S-502 or the Urea Unit. T ABLE 27 A MMONIA C OMPOSITIONS

NH3

AFTER

L ET -D OW N V ESSEL V-502

99.94 %


10.3 Urea Unit The unit manages the urea production from raw materials: 

Ammonia (liquid)



Carbon dioxide (gas)

These raw materials are provided by the ammonia unit, are reacted to form ammonium carbamate, which dehydrates to give urea. Urea synthesis is divided into following sections: 





High pressure section o

Urea synthesis

o

Stripping

o

Carbamate recovery

Medium pressure/Low pressure section o

Ammonia recovery

o

Carbon dioxide recovery

Vacuum section o

Urea concentration

60


Reactor

Vacuum Separators

Brilling Bucket

R-101

MV-106/7

ME-109

Stripper

Pre-concentrator

Conveyer Belts

E-101

E-150

ME-112 A/B/C/D/E/F

LPD E-103

Bagging and Shipment

MPD E-102

61

F IGURE 17 U RE A S YNTHESIS L OO P

10.3.1 High Pressure Section The purpose of the section is to synthesize urea from the reaction of liquid ammonia and carbon dioxide in the urea reactor R-101 and to decompose the unconverted carbamate carbamate in the stripper to carbon dioxide, ammonia and water, which are then condensed, absorbed and recycled back to the reactor with the help of an ejector system. The major control parameters of HP section include oxygen content in carbon dioxide gas,


62

its efficiency, increase in retention time, increase in biuret formation and hydrolysis reaction. A low level will permit gases to escape to MP section, increasing its pressure excessively. 2

The liquid ammonia coming from plant at - 4°C and 24 kg/cm , is collected in ammonia receiver tank V-101 after pre-heating to nearby ambient temperature in the ammonia pre-heater E-109. From V-101 it is fed f ed through ammonia booster pump P-105 to the high pressure motor driven ammonia pumps P-101 A/B/C. The three low speed, heavy duty reciprocating pumps boost the 2

pressure to 232 kg/cm . Before entering the reactor, ammonia is used as a drivi ng fluid in carbamate ejector EJ-101, where carbamate coming from the bottom of the carbamate separator MV-101 is injected in to the reactor R -101 along with ammonia. 2

The carbon dioxide received from urea plant at 51°C and 0.29 kg/cm is compressed by a 2

centrifugal compressor K-101 to 100°C and 160 kg/cm . A small quantity quantity of air is added to passivate the stainless steel surfaces of HP synthesis section, protecting from the corrosive action of ammonium carbamate. HP section is heated uniformly prior to start-up. This prevents the thermal stresses in materials and avoids the possibility of crystallization due to cold piping. The rate of heating is monitored not exceed more than 40°C/hr till 100°C and 15 – 20°C/hr for 100 – 150°C.


63

urea conversion. The reactor volume is such as to give the residence time of about 45 minutes at full capacity. T ABLE 28 S OLUTION C OMPOSITION

NH3 CO2 H2O Urea Total

AFTER

R EACTOR R-101

32.13 % 15.82 % 19.67 % 32.38 280403 kg/h

The reaction products leaving the reactor enter the stripper E-101, which operates as the same pressure as reactor. The mixture is heated by MS as i t flows down the falling film exchanger. The carbon dioxide content of the solution is reduced by stripping action of ammonia as it boils out of the solution. Almost 80 % of carbamate is decomposed in stripper. The over head gases from the top of the stripper enter the carbamate mixer ME-106 along with carbonate solution from the discharge of MP carbonate pumps P-102 A/B. Mixed phase then enters the kettle type carbamate condensers E-105 A/B, where the total mixture, except for few inerts is condensed and recycled back to the reactor. Inerts are removed through carbamate separator MV-101, which sends them to the medium pressure decomposer holder ME-102, to passivate the equipment. The bottom product of stripper goes to the MPD top separator MV-102. T

29 S

C

S

E-101


64

The exchangers where urea is purified are called decomposers because the residual carbamate is decomposed in them giving ammonia and carbon dioxide.

10.3.2.1Medium 10.3.2.1 Medium Pressure Decomposition The solution with low residual carbon dioxide content, leaving the bottom of the stripper is expanded at the pressure of 18 ata and enters the MPD E-102 (falling film type). MPD is divided in to three parts: 

Top separator MV-102; released flash gases are removed before the solution enters the tube bundle



Decomposing Exchanger E-102; residual carbamate is decomposed and the required heat is supplied by means of MC flowing out of the stripper



Bottom Holder ME-102; holds the solution to avoid their escape to LP section

The ammonia and carbon dioxide rich gases ay 134°C and 17.2 ata leaving the top separator are sent to the medium pressure condenser E-107 through the shell of E-150, where they are partially absorbed in aqueous carbonate solution coming from the recovery section. The absorption heat is removed by cooling water. A tempered water circuit is provided to prevent


65

A current of inert gases saturated with ammonia with minimum carbon dioxide residue (20 – 100 ppm) comes out from the top of the rectification section. The bottom of the solution is recycled by the low speed reciprocating pump P-102 to mixer ME-106 in the synthesis recovery section. Ammonia with inert gases leaving the column top is mostly condensed in the ammonia condenser E-110, where the condensation heat is removed by cooling water. From here the two phases are sent to the ammonia receiver V-101 through two different lines. The inert gases, saturated with ammonia, leaving the receiver, enter the ammonia pre-heater E-109 where an additional amount of ammonia is condensed and the condensation heat is recovered by heating the cold ammonia from the urea plant. The condensed ammonia is recovered in V-10. The inert gases with the residue ammonia contents are sent to the MP falling film absorber E-111. Where they meet counter current flow of water which absorbs gaseous ammonia. The absorption heat is removed by MP absorber C101 by means of centrifugal pump P-107. The upper part of the medium pressure absorber consists of three valve trays (C-103) where the inert gases are submitted to a final washing by means of the same absorption water. This way, inerts are vented practically free from




66

Top separator (MV-103); where the released flash gases are removed before the solution enters the tube bundle



Decomposition section (E-103); where the last residual carbamate is decomposed and the required heat is supplied by means of steam saturated at 4.5 Ata.



Bottom holder (ME-103); where gases are prevent from their escape to vacuum section

The gases leaving the top separator are sent to low pressure condenser E-108 where they are absorbed in an aqueous carbonate solution coming from the waste water treatment section. The absorption heat is removed by cooling water. From the condenser bottom the liquid phase, with the remaining inert gases, is sent to the carbonate solution tank V-103. From here the carbonate solution is recycled back to the medium pressure condenser E-107 by means of centrifugal pump P-103. The inert gases, which essentially contain ammonia vapor, flow directly into the low pressure falling film absorber E-112 where the ammonia is absorbed by a countercurrent water flow. The inert gases, washed through the low pressure inert washing tower C-104, are collected to vent practically free from ammonia. T ABLE 31 S OLUTION C OMPOSITIONS A FTER LP D E-103


67

vacuum pressure of 0.4 ata. Then in the second chamber of the pre -concentrator the solution exchanges heat with MPD top gases thus causing more water to vaporize. T ABLE 32 S OLUTION C OMPOSITIONS A FTER P RE -C ONCENTRATOR E-150

NH3 CO2 H2O Urea Total

0.38 % 0.1 % 16.24 % 83.28 % 108928 kg/hr

Then the bottom product with water content and concentrated urea is sent to first vacuum separator exchanger E-114 operating at 0.4 Ata. The mixed phase coming out from E-114 enters the gas-liquid separator MV-104, while the solution enters the second vacuum concentrator E115 operating at the pressure of 0.04 Ata. The mixed phase coming out from E-115 enters the gas-liquid separator MV-107 where from the vapours are extracted by the second vacuum system ME-105 while the melted urea is separated in the holder ME-107. The water thus removed is sent to the tank T-102, the water production ratio with carbon dioxide inlet is 0.67:1. The melted urea leaving the second vacuum separator MV-107 is sent to the prilling bucket ME109 by means of centrifugal pump P-108.The urea coming out from the bucket in the forms of


68

An injection of a small quantity of air in the bottom of the tower is provided to passivate the tower itself and the overhead condenser. The air is collected to vent from V-110. The tower is is provided with five motor driven conveying belts (ME- 112 A/B/C/D/E) that transports urea to the bagging section. T ABLE 34 E XPECTRED U RE A Q UALITY U ALITY

Nitrogen content Biuret content Moisture Prill size range Temperature

46.3 min 0.8 max 0.225 max 1 mm – 2.4mm 65°C max

10.3.4 Waste Water Treatment Section The water containing ammonia and carbon dioxide coming from the first and second vacuum separators MV-106 and MV-107 respectively is collected in waste water collector tank T-102. It is then pumped to waste water distillation tower C-102 operating at pressure of about 2.5 ata. Before entering the top of the column, the solution is pre-heated in a heat exchanger E-118 by means of the distilled water flowing out from the bottom of the tower. In the column ammonia and carbon dioxide are stripped by means of vapor produced in the re -boiler E-116. Column is divided by a chimney tray which directs the bottom product of top sect ion to a hydrolyser R102 through a heat exchanger E-119 A/B. The pump P-121 i s used for service. Hydrolyser


69

10.4 Bagging and Shipment Unit Urea from urea plant is transferred to bagging unit through belt conveyers. There are three areas in unit: 

Area 12 ( storage + fresh feed belts)



Area 13 ( cleaning cleaning system or screening and recycling)



Area 14 ( dispatching area , packing , stitching)

Urea is fed to hoppers in area 12, there are two main kinds of hopper: 

Hopper for fresh feed



Hopper for both fresh and recycle feed

Hopper feed urea to feeders for being transferred to the belts. Bags used for packing are woven poly-propylene bags. Inside covering of bag is made of nylon to prevent incoming and outgoing of moisture. In order to remove dust there is a suction air system of cleaning. In air cleaning system SOVs operate and separate air from dust by pressure


70

11 Conclusion The four week internship at production unit FFC MM developed an understanding of urea fertilizer production. Experience and exposure was not only limited to process flow but was widened to operating logics, process control and economics, production techniques and problem handling and troubleshooting.

The plant division and design, management and operation enhanced the concept and perspective about safe and smooth process.

Literature review from TTC library, study of PFDs, manuals and SOP of different plant areas and equipment, discussion with engineers and technical staff and visit to plant site added a sound potion of knowledge.

The cooperative coordination of management and staff raised the morale in the journey of


71

12 Citations and Bibliography API. (1987). Classification of Locations for Electrical Installations in Petroleum Refineries. Washington: American Petroleum Institute. FFC Safety Section. (2004). Emergency Response Information. Mirpur Mathelo: Fauji Fertilizer Company Ltd. FFC Safety Section. (2010, June 22). Safety Orientation Training. Mirpur Mathelo, Sindh, Pakistan. Industrial Risk Insurers. (1990). Plant Layout and Spacing for Oil and Chemical Plants. Hartford: Industrial Risk Insurers. Ludwig, E. E. (1979). Applied Process Design for Chemical and Pharmaceutical Plants. Houston Tex.: Gulf Publishing. M. Yaqoob Ch. (1987). Process and Operating Manual for Utilities Plant. Mirpur Mathelo: PakSaudi Fertilizers Limited. Marsh & McLennan, Inc. (Published Annually). Large Property Damage Losses in th Hydrocarbon-Chemical Industries (III ed.). Chicago: Marsh & McLennan, Inc.,.

National Fire Protection Association, N. (2002). Electrical Installations in Chemical Plants. Quincy: National Electrical Code.


72

Richard W. Prugh. (2006). Safety. In Kirk-Othmer, & A. Seidel (Ed.), Encyclopedia of Chemical Technology (5th ed., Vol. 21, pp. 826-869). New Jersey, USA: John Wiley & Sons, Inc.

Speight, J. G. (2002). Chemical Process and Design Handbook. New York: McGraw-Hill. U.S. Bureau of Labor Statistics. (n.d.). Incident Rates. Retrieved July 8, 2010, from U.S. Department of Labor: www.bls.gov/iif/oshwc/osh/os/ostb/355.pdf www.bls.gov/iif/oshwc/osh/os/ostb/355.pdf Utilities Unit. (2009). Utilities Production Manual; Pretreatment of Water. Mirpur Mathelo: Fauji Fertilizer Company Ltd.


Appendix I FFC MM Site Map

A


B

Appendix II FFC MM Plant Safety Policy (Policy is released from the office of GM)

FFCrecognizes the significance of maintaining an injury free environment at plant and therefore must strive to avoid any injury to personnel and any damage to equipment equipment etc. In order to achieve this, Management spells out (FFC Safety Section, 2004) the plant safety policy and expects all employees to comply. 1)

The management shall always remain strongly committed to the cause of safety.

2)

Safety shall be given at least the same importance as production.

3)

Safety shall have a due consideration in performance appraisal of each employee.

4)

Management believes that God willing most accidents can be prevented since most of them are caused by human errors and omission.

5)

As and when an accident occurs, the investigation shall be carried out on high priority.

6)

The company shall provide safety training and facilities to all employees, whereas working safely is the condition of employment.

7)

Adequate personal protective shall be provided to employees against hazards at plant full compliance shall be demanded.

8)

The Management shall formulate safety regulations / procedures while employees shall comply with these regulations and procedures.

9)

The contractors shall also follow Company's safety discipline.


Appendix III FFC MM Plant Safety Rules and Regulations All operating areas of the plant are hazardous, because of the fluids handled and the kind of operations involved. Therefore following rules & regulations (FFC Safety Section, 2004) are approved for compliance: 1)

Smoking is not allowed in the operating areas except in the offices and smoking cabins (where provided) or designated areas.

2)

It is forbidden. To carry out any repair/maintenance without a valid work permit

3)

Wearing of safety shoes is mandatory in the plant.

4)

Use of safety helmet, glasses & escape mask is mandatory in operating areas except where exempted.

5)

Use special personal protective equipment where required.

6)

Observe safety procedures/regulations as prescribed or advised for accomplishing all jobs at the plant.

7)

All accidents, near misses and injuries on the job should be reported to immediate supervisor and safety section without loss of time.

8)

It is forbidden to remove or modify safety locks and protection devices without authorization.

C


D

Appendix III Process Flow Diagrams

Figure 19 PFD (Utility): Water Pre-treatment I........................................................................ E

Figure 20 PFD (Utility): Water Pre-treatment Pre -treatment II................................................. ....................................................................... ...................... F

Figure 21 PFD (Utility): Water Treatment ........................................................................... ............................................................................... .... G

Figure 22 PFD (Utility): Instrument Air Plant..................................... Plant........................................................................... ...................................... H

Figure 23 PFD (Utility): Natural Gas Station .............................................. ............................................................................. ............................... I


F IGURE 19 PFD (U TILITY ): W ATER P RE - TREATMENT I

E

Internship ’10 Report (Production Unit) HLA-03 LlA-04

09-ME-926 Clarified Water Distribution System

Prepared by AYAZ Reviewed by MF Utilities FFC MM

09-ME-926 Clarified Water Basin

V-40

L 09-LIC-01 Vent

V-11

V-24

Tube Well Water

09-T-920 TUBE WLL WATER Filtered water tank

V-16

V-18

V-6

V-7

09-MP-923-A

V-15

V-14

V-8

09-MP-923-B

09-MP-923-C

V-9 V-20

V-12

V-19

Make up water to E-800-A-J

Make up water to E-800-K-L-M BMR

V-21

V-22

V-13

09-LIC-02 0 2 9 T o t r e t a w 09-SD-14 d e r e t l i F

P-13

09-MP-902-A

09-MP-902-B

09-MP-926

09-MP-926-B

09-SD-16

09-V-920-A-D

K-920

09-SD-11 09-SD-12

MK-920

F IGURE 20 PFD (U TILITY ): W ATER P RE - TREATMENT II

09-SD-15

F


F IGURE 21 PFD (U TILITY ): W ATER T REATMENT

G


F IGURE 22 PFD (U TILITY ): I NSTRUMENT A IR P LANT

H


F IGURE 23 PFD (U TILITY ): N ATURAL G AS S TATION

I


F IGURE 24 PFD (U RE A)

J


F IGURE 25 PFD (A MMONIA ): F RONT E ND

K


F IGURE 26 PFD (A MMONIA ): B AC K E ND

L

Internship Report: (Production Unit)

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