internship report at fauji fertilizer company

Internship Report (Production Unit) i

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)

Prepared by

Osama Hasan Undergraduate Student

School of Chemical and Materials Engineering (SCME)

National University of Sciences and Technology (NUST)

Email: [email protected]

Contact: 0345-3034516

July 2010

Internship Report (Production Unit) ii

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.

It is anticipated that response will be reflected.

Regards

Osama Hasan

Undergraduate Student

School of Chemical and Materials Engineering (SCME)

National University of Sciences and Technology (NUST)

H-12 Campus, Islamabad – 44000

2008 – NUST – BE – CHEM – 27

Email: [email protected]

Contact: 0345-3034516

Internship ’10 Report (Production Unit) iii

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 Office,

For bringing the opportunity of this excellent learning and exposure;

And last but never the least

Management and Staff of Fauji Fertilizer Company Mirpur Mathelo

Especially Unit Managers, Shift Engineers, Supervisors and Operators,

For their utmost help, guidance and time

Which made author make most of his internship at plant site;

Internship ’10 Report (Production Unit) iv

3 Table of Contents

1 Declaration ...............................................................................................................................ii

2 Acknowledgements ................................................................................................................. iii

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

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

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

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

7 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

8.4.2 Treatment ................................................................................................................. 6

8.5 Safety .............................................................................................................................. 11

8.5.1 Process and Production Safety ............................................................................... 12

8.5.2 Personal Protection Equipment .............................................................................. 14

8.5.3 Design of Facilities .................................................................................................. 15

8.5.4 Operation of Facilities ............................................................................................. 18

8.5.5 Human Resource Management .............................................................................. 18

8.5.6 Disaster Planning .................................................................................................... 19

9 Safety Section........................................................................................................................ 22

9.1 Activities ......................................................................................................................... 22

9.2 Safety Training ................................................................................................................ 25

9.2.1 Importance of Safety at Plant ................................................................................. 25

Internship ’10 Report (Production Unit) v

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

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

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

10 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

10.3.1 High Pressure Section ............................................................................................. 61

10.3.2 Medium/ Low Pressure Section .............................................................................. 63

10.3.3 Vacuum Section ...................................................................................................... 66

10.3.4 Waste Water Treatment Section ............................................................................ 68

10.4 Bagging and Shipment Unit ........................................................................................ 69

11 Conclusion ............................................................................................................................. 70

12 Citations and Bibliography .................................................................................................... 71

Appendix I ....................................................................................................................................... A

FFC MM Site Map ............................................................................................................................ A

Appendix II ...................................................................................................................................... B

FFC MM Plant Safety Policy ............................................................................................................ B

Internship ’10 Report (Production Unit) vi

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) .................................................................... 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

Figure 14 Demin Lines (Area 09) ................................................................................................... 35

Figure 15 Boiler Network .............................................................................................................. 43

Figure 16 Gas Purification Section (Area 03) ................................................................................ 51

Figure 17 Urea Synthesis Loop ...................................................................................................... 61

Figure 18 FFC MM Site Map ............................................................................................................ A

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

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

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

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

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

Figure 24 PFD (Urea) ........................................................................................................................ J

Figure 25 PFD (Ammonia): Front End ............................................................................................. K

Figure 26 PFD (Ammonia): Back End ............................................................................................... L

Internship ’10 Report (Production Unit) vii

5 List of Tables

Table 1 Degree of Hardness ............................................................................................................ 6

Table 2 Alkalinity Indication (Utilities Unit, 2009) .......................................................................... 6

Table 3 Water Quality 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

Table 21 Gas Compositions after Benfield Absorber C-302 ......................................................... 53

Table 22 Carbon dioxide Composition from Benfield Regenerator C-301 ................................... 54

Table 23 Gas Composition after Methanator R-311 ..................................................................... 55

Table 24 Gas Compositions after Compressor K-431/432 ............................................................ 57

Table 25 Gas Compositions of Circulating Synthesis Gas Before Convertor R-501 ...................... 58

Table 26 Gas Compositions after Convertor R-501 ...................................................................... 58

Table 27 Ammonia Compositions after Let-Down Vessel V-502 .................................................. 59

Table 28 Solution Composition after Reactor R-101 .................................................................... 63

Table 29 Solution Concenrtation after Stripper E-101 ................................................................. 63

Table 30 Solution Concentrations after MPD E-102 ..................................................................... 65

Table 31 Solution Compositions After LPD E-103 ......................................................................... 66

Table 32 Solution Compositions After Pre-Concentrator E-150 ................................................... 67

Table 33 Solution Concentrationss After Vacuum Separator MV-106 and MV-107 .................... 67

Table 34 Expectred Urea Quality .................................................................................................. 68

Table 35 FFC MM Plant Area Description ....................................................................................... A

Internship ’10 Report (Production Unit) viii

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

MS Medium Steam

NEQS National Environment Quality Standards

NSC National Safety Council, USA

OSHA Occupational Safety and Health Administration

PLC Programmable Logical Control

QPM Quality Procedures Manual

SDV Shut Down Valve

SOP Standard Operating Procedures

SOV Solenoid Operating Valve

TDS Total Dissolved Solids

TG Turbo Generator

TTC Technical Training Centre, FFC MM

UM Unit Manager

WTCR Water Treatment Control Room

Internship ’10 Report (Production Unit) ix

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; bags the urea product and sends it to the consumer 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

dioxide removal and recovery, compression and gas synthesis section. Urea unit develops an

exposure to handling of chemicals from urea synthesis to its purification through stripper, MPD,

LPD, pre-concentrator, vacuum separators to the prilling bucket. Bagging shipment unit gives an

understanding of meeting the consumer requirements in easy way.

These units are such designed and operated to ensure safety of personnel and plant. Process

optimization in economizing the process in terms of heat load recovery, production and

capacity is the governing factor.

Internship Report (Production Unit) 1

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 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

Fertilizer Company Limited). The plant site at Mirpur Mathelo ex Pak Saudi Fertilizers Limited

(PSFL) was acquired from National Fertilizer Corporation (NFC) in 2002. The capacity was

increased through de-bottle necking of plant in 2008, to increase the production to 2300 MeT

urea per day.

The report is a brief on process operation in production unit of FFC MM. It reflects the

understanding of the author about the plant areas; developed during his four weeks internship

a plant, through study of literature, interaction with operation managers and staff and site

observation.

Internship ’10 Report (Production Unit) 2

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

and carbon dioxide gas, it has the highest nitrogen content other than ammonia (82%) which

extremely disastrous to use openly.

8.2 Ammonia Manufacture

Ammonia is a colorless gas with a penetrating pungent-sharp odor in small concentration that,

in heavy concentrations produces a smoothing sensation when inhaled. Ammonia is water

soluble forming a strongly alkaline solution of ammonium hydroxide and the aqueous solution

is called ammonia water, aqua ammonia. Ammonia burns with a green yellowish flame.

The first breakthrough in the large scale synthesis of ammonia resulted from development of

Haber’s process in 1913 in which ammonia was produced by direct combination of two

elements: nitrogen and hydrogen, in the presence of a catalyst (iron oxide with small quantities

of cerium and chromium) at a relatively high temperature (550°C) and under a pressure of

about 2940 psi (20.3 MPa).


N2 + 3H2 → 2 NH3

FIGURE 1 AMMONIA MANUFACTURE FROM HYDROGEN AND NITROGEN BY HABER PROCESS

In the Haber’s process, the reaction of nitrogen and hydrogen gases is accomplished 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 hydrocarbon such as 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 either case a nitrogen-hydrogen mixture is furnished

for ammonia manufacture. (Speight, 2002)

8.3 Urea Manufacture

Urea (carbamide) is a colorless crystalline solid, somewhat hygroscopic, that sublimes

unchanged under vacuum at it melting point and decomposes above the melting point at

atmospheric pressure producing ammonia (NH3), isocyanic acid (HNCO), cyanuric acid (HNCO3),

biuret (H2NHCONHCONH2) and several other minor products. Urea is very soluble in water

(being a component of urine), soluble in alcohol and slightly soluble in ether. There are several

approaches to the manufacture of urea, but the principal method is that of combining carbon

dioxide with ammonia to form ammonium carbamate.

CO2 + 2NH3 → NH2COONH4

The exothermic reaction is followed by an endothermic decomposition of the ammonium

carbamate.


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 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.

FIGURE 2 UREA PRODUCTION FROM AMMONIA AND CARBON DIOXIDE

The mixture formed is approximately 35% urea, 8% ammonium carbamate, 10% water and 47%

ammonia. It is cooled to 15°C and the ammonia is distilled at 60°C. The residue from the

ammonia stills enters the crystallizer vessel at 15°C. More ammonia is removed by vacuum. The

resulting slurry is centrifugal. All excess nitrogenous materials are combined and processed into

liquid fertilizer which contains a mixture of all these materials. (Speight, 2002)

8.4 Industrial Water

Water used in industries comes from natural sources like rivers, lakes and wells. This water is

likely to contain both dissolved and suspended solids even though they may appear perfectly

clear. Because water circulates many times through pipes, exchangers, cooling towers and

basins, it picks up more/less solids. When water evaporates, dissolves solids are left behind,

increasing their concentration in the remaining supply. Solubility of these solids varies with

temperature. For example, calcium and magnesium carbonates are less soluble in hot water

than in cold water. When cooling water goes through a heat exchanger, these become

suspended solids. When water containing these salts is boiled in a vessel, it deposits or scales

on the sides and the bottom of the vessel. Scaling decreases the efficiency of equipments and


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, 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

their capacity. Scaling within appliances, pumps, valves causes wear on moving parts. This also

creates insulation problems inside boilers, water heaters and hot water lines and increases

heating cost. Hardness is expressed in ppm or mg/l.

Since calcium carbonate is one of the most common causes of hardness ,total hardness i.e.

usually reported in terms of calcium carbonate (mg/l as CaCO3), using either of two methods.

a) Ca and Mg hardness

b) Carbonate and non carbonate hardness

Hardness caused by calcium is called calcium hardness regardless of the salts associated with it

similarly hardness caused by magnesium is called magnesium hardness. Total

hardness=carbonate hardness + non carbonate hardness. The amount of carbonate and non

carbonate hardness depends on the alkalinity of water (Utilities Unit, 2009).


TABLE 1 DEGREE OF HARDNESS

Ppm Hardness

75 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, 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.

TABLE 2 ALKALINITY INDICATION (UTILITIES UNIT, 2009)

Alkalinity Indication

2 P = M All alkalinity is due to carbonates.

2 P < M Both carbonates and bicarbonates are present.

2 P > M Carbonates and hydroxyl are present.

P = M = 0 M – Alkalinity id due to bicarbonates only. Carbonates and hydroxyl are not present.

P = 0 Carbonates, bicarbonates and hydroxyl all are absent. Hardness is permanent.

8.4.2 Treatment

Water is treated to meet certain specifications before use in equipments. It is obtained from

surface and underground sources. Surface water with a higher turbidity is generally rich in

microorganism and contains fewer dissolved solids. It has high concentrations of oxygen and

low concentrations of carbon dioxide (Utilities Unit, 2009). Whereas the underground water is

harder than surface water and contains more alkalinity and dissolved solids. It is clearer and

less sensitive to microbiological contamination than surface waters.

Canal water is preferred due to low hardness despite of high turbidity. This is because turbidity

reduction is less costly than hardness removal. A mixture of both could also be used to make


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.

TABLE 3 WATER QUALITY COMPARISON

Surface Water Underground Water

High Turbidity

Low Hardness

High TDS

Acidic pH

High Dissolved Gases

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

through which they repel each other and do not form flocs to settle under gravity. Coagulation

is the process of destabilizing the small particles by neutralizing their charge and mixing them

thoroughly to enable their contact. In case of low turbidity, previously settled particles (also

referred as sludge) are recycled in order to increase the number of particle collisions and

promote the thickness of sludge. Coagulants (e.g. ferrous sulfate) are used to destabilize the

colloidal particles in waste water so that floc formation can result. Their dosage varies with

respect to turbidity of the source water.

Flocculation is the bridging together of the coagulated particles. Flocculants (e.g.

polyelectrolyte) gathers together floc particles in a net bridging from one surface to another

and binding the individual particles into larger flocs that could settle down under gravity. It is

favored by gentle mixing and a fast pace can destroy the flocs formed. Flocculants work under

the principle that a high molecular wt polymer can attach itself to many suspended particles

creating a low density floc with an increase in the overall size of suspended material.


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

2 Fe3+ + 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 ↓

FIGURE 3 CLARIFICATIONTANK

8.4.2.2 Filtration

Suspended solids are removed from water by filtering the solids in gravity or pressure filter.

These filters have sand and gravel for limiting the flow of suspended particles. Installed in


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 filter bed into waste disposal system.

The flow of other cells is continued through when one cell of the filter is being backwashed.

Gravity Filter Pressure Filter FIGURE 4 SAND 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

demineralization two types of exchange take place a cation exchange and anion exchange.

Cations like calcium magnesium, sodium, potassium, aluminum iron etc are removed in cation

exchanger. Replacement of these cations is carried out with hydrogen ions. Anions such as

chlorides, nitrates, sulfates, bicarbonates and carbonates are replaced with hydroxyl ions in the

anion exchanger after the water has been treated by the cation exchanger. Most ion exchange

units are simple vessels containing a bed of ion exchange resin operated down flow on cyclic

basis. In demineralization process, there are four different types of ion exchange resins:

Strongly acidic cation

Weakly acidic cation

Weakly basic anion

Strongly basic anion

Strong Acid Cation (SAC) resins are used in softening and demineralization applications. In

softening applications, it is used in the sodium form (regenerated with salt) and in

demineralization applications in the hydrogen form (regenerated with acid). A strong acid


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 the resin bed; Type II SBA resins have an exchange

site that is chemically weaker than Type I resins. Therefore, they must be regenerated at lower

temperatures (95º F.) and normally are not used in climates where warm water temperatures

are experienced for a good part of the year. However, Type II SBA resins have the advantage of

a higher initial exchange capacity. They can be the resins of choice in applications that do not

have heated caustic regenerant or where a low silica level is not a critical operating

specification.

Weak base anion (WBA) resins do not exchange any ions but removes by adsorption only those

anions associated with strong acids like hydrochloric, sulfuric and nitric acids (as shown in the

above equation). These resins do not remove carbon dioxide and silica since carbonic and silicic

acids are weak acids. Therefore, they cannot be used to make de-mineralized water without a

SBA resin bed following in the train to remove the carbonate/bicarbonate and silica. The

exhausted resin is when regenerated with any alkali; this simply neutralizes the adsorbed acid

and releases it as a neutral salt. Because the weakly basic exchanger is regenerated simply by

neutralization of the adsorbed mineral acids, so a variety of alkalies can be used for this

purpose. The advantage of using the WBA resin is its efficiency. It is fully regenerated using only


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 from 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.

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

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 resource is the paramount concern of any industry. It

ensures maximum production and loss prevention and contributes to the well being of unit.

With media being more alert and alarming, safety has also become a concern of good name and

repute for organizations. Therefore, industry encourages its members to improve safety

management and manufacturing procedures and practices to minimize hazards.

Occupation Health and Safety Management System, OHSAS 18001:1999 regulates an industry

to remain committed to maintain a safe and healthy environment having the same significance

as proclivity. It inculcates safety culture by specific training, incentives and effective control, to

ensure a safe and healthy working environment. It resolves to attain the highest standards of

safety and health through consistent improvements in on-the-job and off-the-job safety and

working conditions (FFC Safety Section, 2004).

Chemical manufacturers are required to follow detailed steps in ensuring adequate training,

comprehensive operating procedures, thorough analysis of processes of hazards and

investigations of accidents, diligent maintenance of facilities, well-developed emergency plans,

and self audits for compliance (Richard W. Prugh, 2006).


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 of all members of these industries

to as high level as is economically possible (Richard W. Prugh, 2006).

FIGURE 5 PROCESS SAFETY CONTROL H IERARCHY

8.5.1 Process and Production Safety

Process and production hazards could be minimized through a hierarchy of controls that

essentially fall into two (Prugh, 1992) categories, i.e.

Engineering Controls

Administrative Controls

8.5.1.1 Engineering Controls

Engineering controls may be subdivided into those providing inherent safety and those

involving process equipment and conditions.

Those providing inherent safety controls include (Richard W. Prugh, 2006):

i. Intensification: Minimizing the amount of hazardous material or hazardous operations

Process Safety Control

Engineering

Inherent Safety

Process Equipment and Conditions

Administrative


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 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 inspections and testing

3) Process Hazards Analysis; maintaining program integrity

4) Limiting Personnel Exposure; limiting access and proving personal protective equipment

5) Emergency Procedures; for escape and evacuations

FIGURE 6 EMERGENCY D IRECTION SIGNBOARD (FFC, MM)

The OSHA regulations require that Material Safety Data Sheet (MSDS) be developed for all

process materials, so that the hazard data can be communicated to employees (Occupational

Safety and Health Administration, 1999).


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.

Starting in 1994, employers are required by OSHA (Occupational Safety and Health

Administration, 1999), to perform hazards assessments to determine if workplace hazards are

present that require personal protective equipment (PPE). This could include hard hats, safety

glasses, respirator masks, gloves, safety shoes, and also may include long-sleeve shirts, long

pants, and nets over long hair. Also, the hazards assessment may require the removal of wrist

watches and rings. If such hazards are present, the employer is to document the hazards

assessment, select appropriate PPE, and require that employees properly use that PPE and

conform to other requirements. The OSHA standard does not require that the employer

purchase and provide employees with the needed PPE, but many employers have accepted a

responsibility for furnishing the PPE to employers. (Richard W. Prugh, 2006)


(a)

(c)

(b)

(d)

FIGURE 7 INTERNEE PERSONAL PROTECTIVE EQUIPMENT (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

which are assessment of hazards, based on the flammability of materials, reaction energy, and

presence of highly toxic materials (Ludwig, 1979). For instance, FFC MM is located in isolation

from city population in order to avoid any public damage due to ammonia leakage. An

adequate water supply for process cooling and fire fighting is a vital necessity. Prevailing winds

are also considered. At FFC MM, Masuwah Canal that flows from between the plant site and

township, acts as an ample water supply source.

Open areas around the operating units of a plant act as buffers within the plant and to the

surrounding community. Sufficient clearance is allowed so that if tall structures collapse, other

on-site buildings or equipment, or off-site properties are not affected. Adequate roadways

providing entry to the plant are extremely important, and multiple entries and exits are

advisable. An overcrowded plant can lead to damage or shutdown of adjacent units and may

impede the movement of vehicles and materials in case of emergency (Industrial Risk Insurers,

1990).


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 locations and office buildings.

Access to all parts of a plant, including 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 systems within the plant,

from outside the plant, could be prohibited or tightly limited 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

8.5.3.2.1 Services and Facilities

Principal electric power lines are run underground to reduce the probability of damage from

exterior cause like weather and vehicles. Transformer stations and switchgear are accessible to

only authorized personnel. Repair works are carried out after ensured safety of both process

and personnel. In order to secure the stake, FFC MM has regulated a written permit system in

production area to ensure that any sort of work is being done after prior information the

concerned authorities and staff. The following eight types of work permits are issued by shift

engineers for repair work at unit:

1. Cold Work Permit; low temperatures are required

2. Hot Work Permit; fire is used during work

3. Instrument Work Permit; instruments are replaced or repaired

4. Electrical Work Permit; electricity supply is to be altered

5. Vehicle Entry Work Permit; vehicle has to be used for assistance

6. Excavation Work Permit; digging is to be done


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.

TABLE 4 NATIONAL ELECTRICAL CODE, NEC (NATIONAL FIRE PROTECTION ASSOCIATION, 2002)

Type Of Hazard Degree of Process Containment

Class I: flammable gas and vapor Division I

Open

Division II

Closed Class II: organic, metallic, or conductive dusts

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

Water mains are connected to plant fire mains at two or more points, so that a sufficient water

supply can be delivered in case of emergencies. The plant loop and its branches are adequately

valved so that a break in any main can be isolated with affecting the principal part of the

system. Booster pumps could also be installed for maintaining adequate pressures. At FFC MM,

fire mains, fire pumps, isolation valves, and fire protection system are tested at 1500 hours on

every Wednesday in Fire Drill

Special water mains are used to supply untreated water to large plants located nearby a water

source in case of emergency.

8.5.3.2.3 Safety Showers

Safety showers and eyewash fountains or hoses are installed where corrosive or toxic materials

are handled. The valve handles for all safety showers are at the same height and position,

relative to the shower head, and operate in the same way and direction. Water to outside

showers is heated to a maximum temperature of 27°C by an electric heating cable.


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

FIGURE 8 TYPES OF PLANT OPERATION

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

jobs is done after taking in perspective, these factors. Medical selection is often mandatory for

selection. Medical screening avoids damaging exposures to susceptible individuals for example

people with respiratory ailments are not employed in areas where corrosive atmosphere could

occur.

Training is a significant aspect of any professional organization. At FFC MM, graduate engineers

are inducted as trainee for a minimum duration of one year. Training includes development of

understanding of Standard Operating Procedures (SOP) for each unit or plant and complete

adherence to these procedures. Job-safety analysis is also coming up as practice.

On-the-job training includes (Richard W. Prugh, 2006):

1) Preparing the workers by describing the job and discussing the important points

2) Presenting the operation, encouraging questions, and stressing key points

3) Working under close supervision, with errors being corrected as they occur; and

4) Working alone with frequent follow-up by supervisory personnel

Plant Operation

Start-Up Normal Operation Shutdown Maintenance Safe Work Practice


8.5.5.2 Medical Programs

Large chemical plants have at least one full time physician who works at 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 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 (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

the same time to produce fire, removal of any of which results in extinguishment:

1. Enough oxygen to sustain combustion

2. Enough heat to reach ignition temperature

3. Some fuel or combustible material together, they produce the chemical reaction that is

fire

FIGURE 9 FIRE TRIANGLE


Fires are classified according to the type of fuel 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:

TABLE 5 CLASSIFICATION OF FIRE (OSU, 2005)

Fire Fuel Source Examples

Class A Solid Combustibles Wood, Paper, Cloth, Trash, Plastics

Class B Flammable Liquids and Gases Gasoline, Oil, Grease, Acetone

Class C Electrical Fires Energized Electrical Equipment

Class D Combustible Metals 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 Class D

FIGURE 10 FIRE EXTINGUISHER LABELS

For combustible solids and high flashpoint liquids, water can be used alone to extinguish fire.

Water has an additional benefit as a result of its high specific heat and high latent heat of

vaporization. It can be used to cool equipment, structures, and containers of hazardous

materials, even when extinguishing is difficult. Water is the preferred fire control medium

(Richard W. Prugh, 2006).

The extinguishing capability of water can be improved by adding foaming materials. Foam are

formed by addition of proteins and similar synthetic materials and aerating at nozzles to make a

blanket which floats on flammable materials. As foam excludes air, and reduced volatilization, it

is used to cover spills (Richard W. Prugh, 2006).

In some cases, extinguishment of fire by means of oxidant reduction is more effective. These

include inert gases like nitrogen, carbon dioxide, halogenated hydrocarbons, or noble gases

(Richard W. Prugh, 2006).


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 cylinders are red and black. They range in

size from 5 lbs to 100 lbs or larger. On larger sizes, the 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 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

because it may not be able to displace enough oxygen to successfully put the fire out. Class A

materials may also smolder and re-ignite.

Dry Chemical (ABC) Fire Extinguishers: Dry chemical extinguishers put out fire by coating the

fuel with a thin layer of dust. This separates the fuel from the oxygen in the air. The powder

also works to interrupt the chemical reaction of fire. These extinguishers are very effective at

putting out fire.

ABC extinguishers are red and blue. They range in size from 1 kg to 70 kg. The greatest portion

of powder is composed of mono-ammonium phosphate. The extinguishers are pressurized with

nitrogen.


9 Safety Section

FFC believes in “safety first”.

FFC Management is committed to cause of safety and believes that it is everyone's responsibly.

The objective is to improve 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 Time 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)

Engineers (02)

Safety Sub-Engineer (01)

Supervisor (01)

Safety Operators (08)

9.1 Activities

FFC Safety section works in both planning ad execution phases to implement safe work

conditions at plant, with improved working standards and safety. This includes multi-

dimensional efforts team. Key activities (FFC Safety Section, 2010) of unit are as follows:


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 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

concerned units.

Inspection /Audits

Appraise of safety and health risk is associated with equipment, materials, processes and

facilities. It is monitored through routine audits.

Fire Protection

It reduces fire hazards by inspections of facilities and processes. It arranges all type of fire

extinguishers as per need and facilities requirement. It also oversees the design and

operational fire safety of the complex and suggests and coordinates requirement-based

developments.


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.

Accident and Incident Investigation

It determines the facts related to an accident or incident based on witness interviews, site

inspection and collection of other evidences. The focus of this activity is to stop

reoccurrence.

Record Keeping

All data related to accidents/ incidents is recorded and maintained. Safety section reports it

to government and NSC if required. It also maintains safe man-hours data of the company

and reports it to NSC.


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.

TABLE 6 SAFETY DESCRIPTION AS SET BY SAFETY SECTION, FFC MM

The training comprised of:

Importance of Safety at Plant

Use of Personal Protective Equipment

Use of Fire Extinguishers

Ammonia Disaster

9.2.1 Importance of Safety at Plant

FFC produces about 60 % of market’s urea production. Not preparing for plant safety may not

only result in decrease of company production and sale but also in shortage of fertilizer in

market. This may affect the country’s agriculture growth and thus shortage of food for public

followed by price hiking.

S

Search

for hazard

A

Analyze situation

F

Find

causes

E

Eliminate reasons

T

Tell

others

Y

You

are safe


FIGURE 11 EMERGENCY SIREN SEQUENCE (FFC SAFETY SECTION, 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

equipment especially half face mask, which aids in breathing where air is slightly rich in

ammonia or any other hazardous gas or during ammonia disaster. Escape mask provides safety

in situations where concentration of ammonia in air is 50 ppm to 60 ppm.

9.2.3 Use of Fire Extinguishers

TABLE 7 STRATEGY IN FIRE INCIDENT (SUGGESTED BY SAFETY SECTION, FFC MM)

END OF EMERGENCY

90SECONDS

1005

1005

1005

1005

1005

1005

1005

10

SECONDS

FIRE ALARM

DISASTER (HEAVY AMMONIA LEAKAGE)

3010

3010

3010

3010

3010

3010

3010

30

SECONDS

EVACUATION ALARAM

Repeated above disastar alarm

F • Fire

I • Inform management

R • Rescue yourself and others

E • Extinguish / Escape


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 if 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.

FIGURE 12 EMERGENCY RESPONSE (FFC SAFETY SECTION, 2004)

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

and sweep side by side.

Pull Aim Squeeze Sweep

FIGURE 13 PASS APPROACH FOR USING FIRE EXTINGUISHER

Controlling fire can be dangerous; therefore it was advised by the trainer:

1. Assist any person in immediate danger to safety, if it can be accomplished without risk

to you.


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. 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.

TABLE 8 EFFECT OF AMMONIA AT DIFFERENCT CONCENTRATIONS IN AIR

Concentration Effect

Below 5 ppm Harmless

200 ppm Etching to eyes and skin

500 ppm Problem in breathing

More than 700 ppm Death

For personnel outside building or on pathways, it is suggested to take protection is ammonia

shelter made outside the buildings. Standing below water shower would also be safe as

ammonia gets readily dissolved in water, reducing its intensity of attack. Using a moist cloth for

breathing in case no mask is available is highly recommended to avoid choking. On hearing the

ammonia disaster siren, listener should see the wind direction through prilling tower emissions

or air direction sock and move crossway from wind direction.


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 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

Each of the unit has a UM which works with a team of engineers and other technical staff to

manage smooth run of unit. Shift starts with a coordination meeting of production manager,

Unit Managers, staff engineers and engineers; discussing and addressing the problems to be

encountered. Shift engineers coordinate with board men (operators of DCS monitoring facility

at CCR) and operators (at respective areas) for following the agreed plan of action for the shift

or day.

10.1 Utilities Unit

The objective of utilities unit is:


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 raw materials, which are processed and improved

in order to meet the plants’ criterion of quality and ensure a longer life and safety of

equipment.

TABLE 9 PLANT UTILITIES D IVISION

Water Air Natural gas

Cooling water Steam Utility / service water Drinking water

Instrument air Utility / service air Process air

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

Waste Water Disposal

Instrument Air Compression

Natural Gas Station

Power Generation

Auxiliary Boilers and Steam Network

10.1.1 Water Treatment (Area 09)

The core purpose of the installation is to produce two main types of water:

Make-up water for the cooling tower

De-mineralized water for boiler feed


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

pumped to clarifier (ME-920 also called Italfloc) at a flow rate of 250 m3/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:

Pretreatment Section

Demin Lines

10.1.1.1 Pretreatment Section

The pretreatment section produces filtered water from source water through:

Clarification

Filtration

In Clarification, raw water is fed to 1800 m3 capacity clarifier (ME-920) at a flow rate of 1200

m3/hr by means of canal intake pumps (MP-950), mixed in line with ferrous sulfate and

chlorinated water, for enhanced mixing and oxidation of iron from ferrous to ferric. Chemical

(lime and polyelectrolyte) dosage is automatically adjusted according to the feed water rate.


The mixture enters the reaction zone of clarifier (ME-920) and is mixed with recycled sludge

and suspension of lime slurry. Mixing and recycling are ensured by a 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 (MM-

920 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 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 is 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

4 to 5 ppm, it is not necessary to add ferrous sulfate. Chlorination may be considered as a

coagulant aid since it reduces many of the organic substances present in water which inhibit

floc formation (M. Yaqoob Ch., 1987). Chlorinated organic compounds are more readily

removable by the floc and therefore, final quality of effluent is lower in organics.

Polyelectrolyte is anionic polymer that attracts the neutralized suspended particles through its

positive charge and provides them with a nucleus to deposit on. This leads to floc formation

and settling. Lime reacts with soluble hardness molecules and reduces them to insoluble. Lime

dose is a function of pH of raw water and is regularly adjusted.

TABLE 10 CHEMICAL DOSAGE IN CLARIFIER

Chemicals % by weight Mass Flow Rate

Ferrous sulfate 25 1200 kg/hrs

Chlorine 99.5 7.8 kg/hr


Polyelectrolyte 0.3 0.6 kg/hr

Lime 5 675 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

of 800 m3, corresponds to an average retention time of 45 minutes at nominal flow, to shadow

the effects of excess chlorine dosage. Through pumps P-926 (capacity 500 m3/hr) a certain

amount of clarified water is withdrawn from the collection basin for cooling towers make-up,

while the remaining is pumped to the filtration section through P-923 A/B/C.

TABLE 11 CLARIFIED WATER PARAMETERS

Parameter Quantity

Turbidity Lss than 5 NTU

pH 9.9 – 10.2

Free chlorine Less than 0.2 ppm

Iron Less than 0.2 ppm

Alkalinity 2 p = m

Filtration is done to remove residual turbidity of clarified water. The flow rate of fed to filters

from clarified water tank is proportional to the requirement of treatment section. Filtration


encounters the suspended matter in water with sand bed in filters which finally becomes

clogged and demands periodic regeneration after particular operational time.

Clarified water at 70 m3/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 filtered 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

water losses. Filter water is stored in storage tank 09-T-920 having capacity 600 m3/hrs.

10.1.1.2 Demin Lines

The purpose of the demin lines is:

To remove permanent hardness producing ions from the filtered water

To remove dissolved carbon dioxide

Raw water contains many minerals in varying concentrations. When minerals dissolve in water

they form electrically charged particles called ions. These are cations (positively charged ions)

and anions (negatively charged ions) present in relatively low concentrations and permit the

water to conduct electricity. They are sometimes referred to electrolytes. These ionic impurities

can led to problems in cooling and heating systems, steam generation and manufacturing.

Therefore, their removal is necessary. Certain natural and synthetic materials (called ion

exchange resins) have the ability to remove mineral ions from water in exchange for others.

These resins are usually small beads that compose a bed several feet deep through which the

water is passed. Ion exchange resin is an insoluble polymeric matrix containing labile ions

capable of exchanging with ions in the surrounding medium.


TABLE 12 M INERAL IONS IN WATER

Cations Anions Other

Aluminum

Barium

Calcium

Magnesium

Potassium

Sodium

Bicarbonate

Chloride

Sulfate

Nitrite

Silica

Carbon dioxide

FIGURE 14 DEMIN LINES (AREA 09)

Demin lines (de-mineralization section) comprise of two trains of ion exchangers, each with a

capacity of 130 m3/hr and consist of strong cationic exchanger, weak anionic exchanger and a

strong anionic exchanger. Both trains have a common forced draft degasifier (filled with rashing

rings) for decarbonation of decationized water.

Process

Condensate

Activated Carbon Filters V-980 A/B/C

Filtered

Water Tank

T-920

Strong Cation Exchanger V-940

A/B/C

Degasifier

V-941

Weak Anion Exchanger V-942

A/B/C

Strong Anion Exchanger

V-943 A/B/C

Deionized

Water Tank

T - 940

Mixed Beds

V-944 A/B/C

Demineralized Water Tank

T - 901


Filtered water stored in tank (T-920) is 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 film. By this way optional conditions for me removal

of dissolved carbon dioxide are obtained, because the efficiency is directly proportional to the

surface of interface between liquid and gaseous phases and inversely proportion to the

thickness of film. The degasifier water is stored in the vessel V-941 and transferred by pumps P-

940 A/B/C through the strong anion exchangers V-943 A/B to the storage tank T-940.

Percolating on the weak anion resin the water exchanges the anion of strong acids with

hydroxyl ions. The weak anion resin due to its micro-porous structure is also able to remove

from water, in an almost reversible manner, the organic matter. Passing through the strong

anion resin, water exchanges anions of weak acids with hydroxyl ion.

Water is stored in T-940 along with steam condensate, de-oiled by activated carbon filters V-

980 A/B/C. De-ionized water is fed by pumps P-941 A/B/C to mixed beds V-9444 A/B/C, where

final polishing is performed. Water leaving the mix bed is stored in de-mineralized water tanks


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

driven. Inside the two portions of cell special type polypropylene assemblies are placed. These

assemblies are called drift eliminators. There are five pumps for cooling water circulation. One

of these pump is motor driven, four pumps are turbo-driven and are for normal operations. The

turbines for pumps are condensing turbines. The exhaust steam from all the turbines is

condensed in a condenser equipped with vacuum system. Another tower with 2 cells was later

constructed to improve the performance of cooling tower.

Hot water at 42°C from unit returning to cooling towers in enters hot water channel of cooling

towers at 31,000 m3/hr flow rate and rises up through risers located in the centre of each of the

10 cells. Water is distributed to 2 pits and each having 240 nozzles through which water is

showered into the cells, by gravity. The water falling down strikes the polypropylene packing

that increases the water surface area in contact with water and residence time, resulting in


efficient cooling. Evaporation causes cooling and cooled water is collected in 6900 m3 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.

TABLE 13 COOLING TOWER DESIGN DATA

Type Induced Draft / Cross Flow

Flow rate 31000 m3/h

Basin capacity 6900 m3

Number of cells 8 + 2

Ambient air temperature 7°C

Cold water inlet temperature 43 °C

Cold water outlet temperature 32°C

Wet bulb 28°C

Dry bulb 47.8°C

Heat load 341 G cal/h

Air relative humidity 80%

Make up 803 m3/h

Blow down 158 m3/h

Drift losses 0.1 % (31 m3/h)

Evaporative losses 2 % (614 m3/h)

Drift eliminator Polypropylene

Packing Splash type

Nozzle Static / Turbo

Water is the most common and nearly universal solvent known. Solvent property varies widely

and is the property that causes problems for operators. Water evaporation increases the TDS

content of what is left behind; moreover decreased temperature causes several salts to

become insoluble and ready to scale. In order to keep the quantity of salts like calcium,

magnesium, sulfates or silicates minimum, a portion of concentrated water is removed and

make-up water is added. Removal of concentrated water is called Blow Down. There are two

types of blow down: continuous and batch. Continuous blow down remove the sludge

produced in the water basin to waste disposal (Area 16). While batch blow down is me to time

manually to get the samples for the laboratory tests.


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, poly-

phosphates, ortho-phosphates etc.

Water in cooling tower is also treated and filtered to remove impurities, 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

disposal into Masuwah canal. The effluents of major concern are from ammonia, urea and

water treatment plants. The effluents from boilers, carbon dioxide, and absorption unit are

mostly diluents.

TABLE 14 NEQS L IMITS FOR WATER WATER D ISPOSAL

Parameters Permissible Range

pH 6 – 9

Ammonia 40 ppm

TSS 200 ppm

TDS 3500 ppm

COD 150 ppm

Grease & oil 10 ppm

Temperature increase ≤ 3 °C

Chloride 1000 ppm

BOD 80 ppm

Iron 8.0 ppm


Zinc 5.0 ppm

Sulfate 600 ppm

Chromium 1.0 ppm

Conductivity 2500 micro S/cm2

Waste water from all plant sites at a flow rate of 250 – 300 m3/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,

plant might lead to shut down.

Air from process gas compressor in area 04 K-421, at a pressure of 8.5 kg/cm2 is fed to

ammonia receiver tank, during normal running of ammonia compression section. However, the

Area has two stages, double acting, non-lubricating, Y-shaped, motor driven two stand-by

compressor MK-1001/2. The compressor takes air from atmosphere in its first stage amd

discharges at the pressure of 1kg/cm2. Compression heats the air to 160°C, which is than cooled

to 45°C in inter cooler before feeding to the second stage of compression. The second stage

discharges at 8 kg/cm2 and 175°C. Compressed air is then passed though a damping vessel V-

1003/4, fitted with baffles to remove any condensate. Air is then passed through an after cooler

E-1002B/3B, where it is cooled down to 50°C. Downstream of after cooler is fitted with cyclone


separator to remove the condensate water produced as a result of cooling. Cooling is

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.

The air receiver V-1001 has a capacity of 100 Nm3. Air supply from K-1001/1002 is stored at

50°C and 8 kg/cm2. Receiver provides the compressed air to utility air network and air drying

station for instrument air supply. PCV protects vessel by blowing at 9 kg/cm2.

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 MD-

1001 A/B (one in service and other on regeneration), where in moisture is absorbed in activated

alumina. Dried air is finally passed through air filters 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

kg/cm2.

10.1.5 Natural Gas Station (Area 15)

The purpose of natural gas station is to supply natural gas after filtration to meet the demands:

Process gas

Fuel gas

Township supply

Natural gas is drawing from the Mari Gas Field through 16’’ diameter header. Distance between

plant and Mari Gas field is about 20km. Pressure of this natural gas is about 31.5 kg/cm2. Gas is

passed through the two gas filters ME-1501 A/B (one in service, other in standby), which

allow on less than 5 micron size particles to pass through them. Gas circulates

centrifugally due to which velocity increases and heavy particles and mainly liquids are

settled down. The condensate consists of Iron, Manganese and Chlorides. Each filter


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/cm2. Natural gas to

township is supplies at 2.5 kg/cm2 after adding odorizing agent tetra thiophene (THT) to

it.

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 deaerator 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

saturated steam rising up. Water is then collected in a collecting tray and flows down to the re-

boiling section, where water is stripped with rising steam and fed to the storage tank. The

deaerated water is pumped through BFW pumps P-601 A/B/C. The BFW water at 150 kg/cm2

and 110°C flows to flue gas-swept economizer situated in convection zone of furnace. The feed

water is heated to 350°C by a heat exchange with counter current flow of hot flue gases, and

fed to the steam drum. Feed water is then transferred to rear heaters and side tube walls of the

boiler through the down-comers. Uniform partial evaporation is promoted by a fairly even

flame radiation over the furnace walls. The steam-water mixture flows back in to the drum by

natural convection and separated. The saturated steam leaves the steam drum across the

drying unit and reaches the super heater stage, situated in convection zone of boiler furnace.

The three super heaters raise the temperature of steam to 510°C and recycle it back to steam

drum, from where steam is fed to turbine.


FIGURE 15 BOILER NETWORK

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.

The turbine has 14 stages. The High pressure section of the turbine consists of 8 stages all

shrouded blades with moving blades profile milled from a solid forging. The Low Pressure

section of the turbine consists of 6 stages with moving blades profile milled from a solid forging

as well. The impellers are connected on a single shaft. The KS Saturated steam at 105 kg/cm2

Pressure and 510°C temperature is injected in the turbine impeller chanber on the first stage.

The steam apply force on the impellers and get its velocity lower. The velocity head is

converted into pressure head on having large area. Again the steam enters to the next impeller

via nozzles. The pressure head is converted into velocity head and this mechanism continue till

the discharge of the steam from the turbine. Then exit stream is condensed and send to boiler

for reuse.

A generator is connected with the turbine shaft via a gear box to lower down the RPM for

generator. The turbine is rotating at 11,000 RPM where as the generator is designed for 1500

DM Water Tank T-901

BFW Pre-heater

Deaerator

Accumulator Economiser Steam Drum

Boiler Super heater

Turbine


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.


10.2 Ammonia Unit

The core purpose of ammonia unit is to provide the raw materials for urea unit. They 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

o Carbon dioxide Removal; separates carbon dioxide by absorption in Benfield sol.

o Methanation; convert residual carbon dioxide to methane convert

Ammonia synthesis section; hydrogen and nitrogen reacts to give ammonia

Cooling and Storage; product is compressed, cooled and stored

10.2.1 Desulfurization Section (Area 02)

The section removes the sulfur compounds from the natural gas feedstock to avoid poisoning of

catalyst in primary reformer (F-201) and Low Temperature Carbon monoxide Shift (R-205). Unit

consists of two absorbers R-201 A/B (one in use and other on stand-by) with zinc oxide bed;

which reduces sulfur content to about 0.1 ppm by weight. The key reaction is:

ZnO + H2S → ZnS + H2O (I)


Natural gas coming from Maripur gas field through Natural Gas Station (Area 15) has

compositions (Molecular Mass 20.91):

TABLE 15 NATURAL GAS COMPOSITION

H2 0.1 %

N2 19.5 %

CO2 9 %

CH4 71 %

C2H6 0.2 %

Natural gas at a flow rate of 36472 Nm3/h at 30 kg/cm2 and at 38°C is compressed in natural gas

compressor K-411 to 40 kg/cm2 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 zinc 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)

Enable reaction of sulfides and disulfides with sulfur absorption catalyst (330°C – 440°C)

Increase the absorption capacity of catalyst (350°C)

Syn gas recycling increases the reaction rate of conversion organic sulfur to inorganic sulfur and

efficiency of catalyst. Hot mixture at 400°C is passed through one of the two sulfur absorbers R-

201 A/B, the other vessel is kept as spare.

TABLE 16 SYN GAS RECYCLE COMPOSITION

H2 74.4 %

N2 24.74 %

Ar 0.23 %

CH4 0.92 %


Each vessel contains 21 m3 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:

KI = 2.5 x 10-6 at 380°C KII = 4 x 10-9 at 380°C

The rate of reaction increases with increase in temperature:

KI = 4 x 10-6 at 400°C KII = 7 x 10-9 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

temperature could vary from ambient to 50 kg/cm2 (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.

10.2.2 Reforming Section (Area 02)

The section produces synthesis gas containing necessary compounds (hydrogen and nitrogen in

ratio 3:1) for ammonia synthesis by catalytic steam reforming of natural gas and addition of

atmospheric air to give nitrogen content to mixture. Endothermic reactions consuming great

deal of energy, govern the process economics.

Section is divided into: primary reformer (F-201) and secondary reformer (R-203). Heat of

reaction is provided in two different ways. In primary reformer, it is provided as indirect heat by

firing. In secondary reformer it is supplied by mixing air into the gas resulting in auto-ignition

temperature conditions. Air supply in later is adjusted to give a desired hydrogen – nitrogen

ratio. Key reactions (reversible) of process are:

C2H6 + H2O ↔ CH4 + CO2 + 2H2 (500°C)


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

pressure at 35 kg/cm2. The third reaction consumes important hydrogen and therefore is

minimized with excess steam to carbon ratio is increased to 3.75:1.

10.2.2.1 Primary Reformer

Primary reformer has a total of 288 reforming tubes installed in two radiant chambers with a

common flue gas channel and 648 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

Tubes are loaded with 31.8 m3 RKS catalyst in form of ceramic rings is impregnated with nickel.

The magnesia-alumina-spinnel catalyst with 17% nickel oxide has stable pore system, high

thermal resistance and a negligible content of silica and other volatile compounds. The crush

point is 300 kg/cm2 and fusion is 2000°C. Catalyst is activated by reducing the oxide to nickel by

steam – hydrocarbon mixture. Deactivation is done through cooling by steam that re-oxidizes it.

The natural gas mixture is pre-heated to approximately 52°C and the passed downward

through the vertical tubes of filled with catalyst; placed inside a fired heater, primary reformer

F-201. Sensible heat is transferred by radiation from a number of wall burners to the tubes.

Methane is reformed through steam yielding an increase in hydrogen and carbon dioxide

content of mixture. Almost 90% of reforming takes place in primary reformer. The gas leaves

the primary reformer at 927°C.


TABLE 17 GAS COMPOSITIONS AFTER PRIMARY REFORMER F-201

H2 65.5

N2 7.14

CO 10.13

CO2 11.44

CH4 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

and reforming the remaining methane. 35 m3 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 mixture contacts with catalyst at the temperature about

1100°C – 1200°C. Some of the catalyst activity is lost during the first high temperature

interaction, but continuous operation decreases the rate to very slow. The sintering

temperature of the catalyst is 1400°C – 1500°C. Activated catalyst should not be exposed to air

at temperatures above 100°C, which would cause spontaneous heating and destruction of

catalyst.

The gas from primary reformer then enters the upper portion of secondary reformer where a

pre-heated stream of 28167 Nm3/h compressed process air at 150°C and 35.5 kg/cm2 is mixed

with the gas. High temperature results in auto ignition and an exothermic reaction that

consumes the oxygen from air. The gas is then passed to the catalyst bed in lower section of the

reformer, where reforming reaction is completed with simultaneous cooling of gas. The outlet

gas leaves the chamber at 972°C and 31 kg/cm2.


TABLE 18 GAS COMPOSITIONS AFTER SECONDARY REFORMER R-203

H2 55.93

N2 22.15

CO 12.14

CO2 9.02

Ar 0.20

CH4 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.

Only inert gases like methane and argon are permissible in lowest possible concentrations.

Carbon monoxide is converted in two shift convertors R-204 and R-205 according to the

following reaction to reduce the concentration to (0.4 % on dry basis).

CO + H2O ↔ CO2 + H2 + (heat)

Reaction increases the hydrogen yield with formation of carbon dioxide which is more easily

removable. After cooling of gas and condensation of water content, carbon dioxide is removed

up to 0.1 %, which is then converted to methane methanator R-311, at the cost of expensive

hydrogen.

CO + 3H2 ↔ CH4 + H2O + (heat)

CO2 + 4H2 ↔ CH4 + 2H2O + (heat)


Inert levels in ammonia synthesis loop are controlled via purging of inerts to keep the level low

and obtain higher production.

FIGURE 16 GAS PURIFICATION SECTION (AREA 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 the activity and quantity, conversion is performed in

two steps:

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

Low temperature shift (LTS); to favor equilibrium conditions

10.2.3.1.1 HT S – Convertor

The HTS convertor R-204 is installed with 61 m3 of SK conventional chromium oxide promoted

iron oxide catalyst, distributed on two beds, each 2.1 m high. Fresh catalyst has highest oxidized

level of iron oxide and therefore is not affected by air, steam carbon dioxide or inerts at

elevated temperatures. Catalyst should not be exposed to heating above 400°C. Methane is not

an inert for the catalyst and reduces it to be spoiled by carbon deposits. Catalyst is therefore

not exposed with reducing agents like hydrogen or carbon monoxide unless absolutely cold.

Catalyst is activated by reduction at 250°C with a mixture of hydrogen and carbon monoxide

after being preheated with steam (inert for catalyst). It is sensitive to salts in water and chlorine

level in gas, while inert to sulfur.

Reforming Section

(Area 02) HTS Convertor

R-204

LTS Convertor

R-205

Benfield Absorber C-302

Methanator

R-311

Ammonia Synthesis Section (Area 05)

Benfield

Regenerator

C-301


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.

TABLE 19 GAS COMPOSITIONS AFTER HTS CONVERTOR R-204

H2 59.66

N2 20.28

CO 2.87

CO2 16.73

Ar 0.19

CH4 0.127

10.2.3.1.2 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

loses its activity if temperature is higher than 250°C – 270°C. 85 m3 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

including 0.1 % hydrogen. Reduced catalyst is pyrophoric and is oxidized before unloading.

Stream from HTS Convertor enters the LTS convertor R-205 where remaining reaction is

completed. The gas leaves the vessel at 235°C and 29 kg/cm2.

TABLE 20 GAS COMPOSITIONS AFTER LTS CONVERTOR R-205

H2 50.54

N2 19.78

CO 0.08

CO2 18.75

Ar 0.18

CH4 0.27

10.2.3.2 Carbon dioxide Removal (Benfield Unit)

The section removes the carbon dioxide formed in shift conversion section by absorption in hot

aqueous Benfield solution containing about 30 wt % potassium carbonate (potash) partly


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. The two upper beds

with bed height 7.7 m and dia 2.5 m contains a total of 75 m3 of 1.5’’ rings. The lower two beds

same bed height but dia 3.50 m contains a total of 148 m3 of 2’’ rings. The 4.5 m dia

regenerator C-301 contains four beds of 450 m3 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 is further cooled through passage

from Benfield re-boiler E-302 and BFW pre-heater E-304 to minimize the temperature to 110°C

and 27.7 kg/cm2. Separator V-304 removes the further traces.

Gas is then passed to the bottom of Benfield absorber C-302, where it flows counter-currently

against the potash solution. A quarter of the solution flows from the top of the column at 70°C,

where as the remainder three fourth flows after the two top beds at 119°C. Process stream

leaves the column at 70°C for methanation. The reason for splitting the streams before entering

the absorber is to reduce the partial pressure, in order to help reduce to the lowest carbon

dioxide traces in process stream.

TABLE 21 GAS COMPOSITIONS AFTER BENFIELD ABSORBER C-302

H2 74.58

N2 24.29

CO 0.48

CO2 0.10

Ar 0.23

CH4 0.33

The rate of reaction for absorption is kept high by the combined effect of relative high

temperature and the activator.


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

regenerator C-301, where pressure is reduced to 5 kg/cm2 to flash the carbon dioxide off.

Remaining is removed from the solution by flowing it downwards through the packed tower in

a counter-current flow with LP steam at 138°C and 0.5 kg/cm2.

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 E-

303 to 70°C and introduce top of the absorber.

The steam – carbon dioxide mixture from the top at 105°C and 0.5 kg/cm2 is cooled in BFW pre-

heater E-305 and condenser E-306 before separation in separator V-301. Here 7874 Nm3/h

carbon dioxide is separated and sent to the urea unit at 45°C and 0.29 kg/cm2, while the

condensed steam is through condensate pumps P-302 A/B to sewer.

TABLE 22 CARBON DIOXIDE COMPOSITION FROM BENFIELD REGENERATOR C-301

H2 1 %

N2 0.5 %

CO2 98.5 %

10.2.3.3 Methanation

The traces of carbon dioxide are poison to reactor catalyst and therefore are converted to

methane (inert) in methanator R-311. Methanation is just the reverse of reforming, supported

by lower temperatures.

CO + 3H2 ↔ CH4 + H2O + (heat)

CO2 + 4H2 ↔ CH4 + 2H2O + (heat)

The reaction is based more upon the activity of catalyst rather than other parameters.

Efficiency is increased through higher temperature conditions but also reduces the life of the


catalyst. The reactor reduces the combined carbon mono and dioxides compositions to less

than 10 ppm with a temperature rise of 30°C.

Methanator R-3111 contains 30 m3 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

at 39°C and 25 kg/cm2.

TABLE 23 GAS COMPOSITION AFTER METHANATOR R-311

H2 74.4 %

N2 24.74 %

Ar 0.23 %

CH4 0.92 %

10.2.4 Ammonia Synthesis Section (Area 05)

The ammonia synthesis takes place in the ammonia convertor R-501 with a catalyst bed,

according to the reaction:

3H2 + N2 ↔ 2NH3 + (heat)

The synthesis being the equilibrium reaction does not reach completion and only a part is

converted to ammonia. Conversion is supported by high pressure and low temperature, but

high rate of reaction demands high temperature. Therefore, a compromise has been made

between theoretical conversion and approach to equilibrium in a single pass over to catalyst.

This gives an optimum level for catalyst temperatures to ensure maximum production.

The synthesis loop consists ammonia synthesis reactor R-501, re-circulating compressors

(integrated with synthesis gas compressor), BFW pre-heat; for cooling the syn gas and


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

270 kg/cm2, 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

beds in a radial direction. It contains a total of 33 m3 catalyst, distributed in three beds with bed

height 5 m3, 10 m3 and 18 m3 respectively. Catalyst size decreases downward in beds, increases

the catalytic activity of smaller particles. The catalyst is stable in 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 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 are all poisons to the catalyst.

The gas compositions for ammonia synthesis loop are characterized by any one of the

following:

Ammonia content

Inert gases content (argon and methane)

Hydrogen to nitrogen ratio

Purity

The hydrogen to nitrogen ration in synthesis loop is of great importance. A small change of ratio

in fresh feed will result in a much bigger change in the ratio in circulating synthesis gas.

Decreasing the ratio in circulating synthesis gas decreases the efficiency of convertor, leading to

an increased ammonia concentration at convertor inlet.


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 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 outlet temperature is about 500°C.

The syn gas from methanator R-311 is compressed in synthesis re-circulation compressor K-

431/432 and fed to the synthesis loop at 39°C and 261 kg/cm2. 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

removed by absorption in the shell side of condensing ammonia chiller E-506 before the gas

enters the convertor.

TABLE 24 GAS COMPOSITIONS AFTER COMPRESSOR K-431/432

H2 74.11 %

N2 24.74 %

CO 10 ppm

CO2 10 pm

Ar 0.3 %

CH4 0.92 %

The carbon dioxide contained in make-up gas will also be removed by absorption in condensing

ammonia. The carbon dioxide will further more react with gaseous or liquid ammonia with

formation of ammonium carbamate. In case of no liquid ammonia, carbamate will separate

from the gaseous phase as a solid which will tend to plug the system. Therefore, make-up gas is


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.

TABLE 25 GAS COMPOSITIONS OF CIRCULATING SYNTHESIS GAS BEFORE CONVERTOR R-501

NH3 3.60 %

H2 63.31 %

N2 21.09 %

Ar 2.44 %

CH4 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

and 269 kg/cm2. 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

inlet) are converted to ammonia therefore it is necessary to recycle the unconverted syn gas to

convertor.

TABLE 26 GAS COMPOSITIONS AFTER CONVERTOR R-501

NH3 15 %

H2 52.94 %

N2 17.62 %

Ar 2.74 %

CH4 10.70 %

Convertor effluent gas from the convertor exit at 325°C and 265 kg/cm2 is cooled to 195°C in

BFW pre-heater E-501 A/B, then in the hot heat exchanger E-502 to 79°C and in the water

cooler E-503°C, where condensation of ammonia starts. Further cooling and condensation takes

place in the cold heat exchanger E-504 to 25°C, in the first ammonia chiller E-505 to 11°C , and

finally in the second ammonia chiller to 0°C. The condensed ammonia is separated from the


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

quantity of inert gases from the synthesis loop. At designed conditions, 7437 Nm3/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

pressure is decreased to 25 kg/cm2.

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 S-

501 and S-502 or the Urea Unit.

TABLE 27 AMMONIA COMPOSITIONS AFTER LET-DOWN VESSEL V-502

NH3 99.94 %

H2 0.015 %

N2 0.015 %

Ar 0.015 %

CH4 0.015 %


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

o Prilling

Waste water treatment section

Optimum temperature conditions and retention time in process are extre3mely important

because high temperature and more residence time causes:

High biuret content

More energy input

More water circulation

Overloading of vacuum condensers and ejectors

Pressure increase in system

Reduced efficiency

These highly disturb the economics of the process and are always prevented.


FIGURE 17 UREA SYNTHESIS LOOP

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 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,

ammonia to carbon dioxide ratio, reactor top temperature, synthesis pressure and stripper

bottom level. A decrease in oxygen content of carbon dioxide from urea section increases the

corrosion of stain less steel (line) surfaces. An increase would result in decrease in urea

conversion. Therefore the range of oxygen content should lie with 0.1 % - 0.7 %. The ammonia

to carbon dioxide ratio is kept more than the theoretical demand of 2:1 to keep the urea

conversion maximum. But an increase than 3.6:1 would cause a part of ammonia to evaporate

from the reactor without being reacted, thus increasing load on MP section for ammonia

recovery. High temperature is mandatory for optimum urea conversion on top. If reactor top

temperature is too low, it may be due to a pressure fault or incorrect ammonia to carbon

dioxide ratio. Optimum synthesis pressure is necessary. Too high pressures may disturb the

degree of condensation in carbamate condensers. A level rise in a stripper causes a decrease in

Reactor

R-101

Stripper

E-101

MPD

E-102 LPD E-103

Pre-concentrator

E-150

Vacuum Separators

MV-106/7

Brilling Bucket

ME-109

Conveyer Belts

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

Bagging and Shipment


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.

The liquid ammonia coming from plant at -4°C and 24 kg/cm2, 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 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

pressure to 232 kg/cm2. Before entering the reactor, ammonia is used as a driving 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.

The carbon dioxide received from urea plant at 51°C and 0.29 kg/cm2is compressed by a

centrifugal compressor K-101 to 100°C and 160 kg/cm2. A small 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.

In the reactor R-101, the ammonia and carbon dioxide react to form ammonium carbamate, a

portion of which dehydrates to form urea and water. The reactions are as follows:

2 NH3 + CO2 ↔ NH2COONH4 ∆H = 37.65 kcal

NH2COONH4 ↔ NH2CONH2 + H2O ∆H = 6.3 kcal

At synthesis conditions, of 188°C and 155 kg/cm2 the first reaction is instantaneous and goes to

completion, the second reaction occurs slowly and determines the volume of reactor. The

fraction of ammonium that dehydrates is determined by the ratios of various reactants,

operating temperature and residence time. The mole ratio of ammonia to carbon dioxide is

3.6:1.0 and the mole ratio of water to carbon dioxide is 0.6:1.0. Excess water will reduce the


urea conversion. The reactor volume is such as to give the residence time of about 45 minutes

at full capacity.

TABLE 28 SOLUTION COMPOSITION AFTER REACTOR R-101

NH3 32.13 %

CO2 15.82 %

H2O 19.67 %

Urea 32.38

Total 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 it 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.

TABLE 29 SOLUTION CONCENRTATION AFTER STRIPPER E-101

NH3 25.03 %

CO2 6.75 %

H2O 24.53 %

Urea 43.69 %

Inets 0.1%

Total 207641 kg/h

10.3.2 Medium/ Low Pressure Section

The purpose of the section is to purify urea by recovering ammonia and carbon dioxide for

being recycled to the reactor. The section is divided into:

Medium Pressure Decomposer

Low Pressure Decomposer


The exchangers where urea is purified are called decomposers because the residual carbamate

is decomposed in them giving ammonia and carbon dioxide.

10.3.2.1 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

carbamate solidification and to keep a suitable cooling water temperature at MP condenser

inlet re-circulating the cooling water by means of the in-line pump P-116.

In the mixture, the carbon dioxide is almost totally absorbed. The mixture from E-107 flows to

the MP absorber C-101 where the gaseous phase coming up from the solution enters the

rectification section.

The column is a bubble cap trays type and performs carbon dioxide absorption and ammonia

rectification. The trays are fed by pure reflux ammonia which eliminates residual carbon dioxide

and water contained in the inert gases. Reflux ammonia is drawn from the ammonia receiver V-

101 and sent to the column by means of the centrifugal pumps P-105.


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 C-

101 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

ammonia. Level in holder ME-102m from where bottom products are fed to LPD section; is very

important because a low level will result in breakthrough of HP gases to LP section and a high

level will increase the residence time followed by biuret formation.

TABLE 30 SOLUTION CONCENTRATIONS AFTER MPD E-102

NH3 6.83 %

CO2 1.86 %

H2O 28.97 %

Urea 62.34 %

Total 145530 kg/h

10.3.2.2 Lower Pressure Decomposer

The solution leaving the bottom of MPD is expanded at 4.5 ata pressure and entered in LPD E-

103 (falling film type). LPD is also divided in to three parts:


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.

TABLE 31 SOLUTION COMPOSITIONS AFTER LPD E-103

NH3 1.67 %

CO2 0.76 %

H2O 28.71 %

Urea 68.87 %

Total 131729 kg/h

10.3.3 Vacuum Section

The urea solution after removal of ammonia and carbon dioxide is concentrated through

evaporation of water in pre-concentrator E-150 and vacuum separators MV-106 and MV-107.

Vacuum separators are employed due to their functioning at low temperature conditions and

less steam consumptions. Further they also reduce the probability of biuret formation.

The solution leaving the low pressure decomposer bottom with about 69% urea is sent to the

pre-concentrator E-150 in which a considerable amount of moisture is flashed off at a near


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.

TABLE 32 SOLUTION COMPOSITIONS AFTER PRE-CONCENTRATOR E-150

NH3 0.38 %

CO2 0.1 %

H2O 16.24 %

Urea 83.28 %

Total 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 E-

115 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 ME-

109 by means of centrifugal pump P-108.The urea coming out from the bucket in the forms of

drops falling along the prilling tower ME-108 and encounters a cold air flow which causes its

solidification. The vapor coming from the top of the tower is condensed into the overhead

condenser E-117.

TABLE 33 SOLUTION CONCENTRATIONSS AFTER VACUUM SEPARATOR MV-106 AND MV-107

Urea 99.62 %

H2O 0.38 %

Total 90291 kg/hr

The carbonate solution is collected in the accumulator V-110. By means of the centrifugal pump

P-115 part of this solution is recycled back to the top of the tower as reflux, the remaining part

of the low pressure condenser E-108. This distilled water containing only traces of ammonia,

after cooling in E-118, is sent to the urea battery limits by means of the centrifugal pump P-114.


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

provided with five motor driven conveying belts (ME-112 A/B/C/D/E) that transports urea to

the bagging section.

TABLE 34 EXPECTRED UREA QUALITY

Nitrogen content 46.3 min

Biuret content 0.8 max

Moisture 0.225 max

Prill size range 1 mm – 2.4mm

Temperature 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 section to a hydrolyser R-

102 through a heat exchanger E-119 A/B. The pump P-121 is used for service. Hydrolyser

decomposes the remaining amount of carbon dioxide and ammonia and sprays it again in the

distillation tower.


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 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

Certain securities concerned in urea transferring include:

Misalignment switches

Pull card

Speed monitors

Thermal overload

Usually every belt has different capacity and speed. Fresh feed belts are have above 90 ton

capacity.


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

lifelong learning and a ChEmE.


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.

National Safety Council. (1988). Fundamentals of Indutrial Hygiene. Chicago.

NSC. (1988). Accident Prevention Manual for Industrial Operations - Administration and

Programs (9th ed.). Chicago: National Safety Council.

Occupational Safety and Health Administration. (1999). Occupational Safety and Health

Standards, Air Contaminants, 29 CFR 1910.1000, and Hazard Communication, 29 CFR

1910,1200. Washington: U.S. Department of Labor.

Occupational Safety and Health Administration. (1999). Occupational Safety and Health

Standars, Respiratory Protection. Washington: U.S. Department of Labor.

OSU. (2005). Fire Extinguisher Training. Ohama: Ohama State University.

Prugh, R. W. (1992). Hazardous Fluid Releases: Prevention and Protection by Design and

Operation. J. Loss Prevention Proc. Inc.


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

Utilities Unit. (2009). Utilities Production Manual; Pretreatment of Water. Mirpur Mathelo: Fauji

Fertilizer Company Ltd.

Internship Report (Production Unit) A

Appendix I

FFC MM Site Map

FIGURE 18 FFC MM SITE MAP

TABLE 35 FFC MM PLANT AREA DESCRIPTION

Area Number Unit Area

Area No. 1 Urea Urea Section

Area No. 2 Ammonia Synthesis Gas Preparation

Area No. 3 Ammonia Carbon dioxide removal

Area No. 4 Ammonia Compression Section

Area No. 5 Ammonia Ammonia Synthesis & Refrigeration

Area No. 6 Utilities Turbo Generator

Area No. 7 Utilities Boiler

Area No. 8 Utilities Cooling Tower

Area No. 9 Utilities Pre-treatment and treatment

Area No. 10 Utilities Instrument Air

Area No. 11 B & S Urea Storage

Area No. 12 B & S Urea storage and fresh feed belts

Area No. 13 B & S Urea screening and recycling

Area No. 14 B & Storage Urea packing and dispatch

Area No. 15 Utilities Natural Gas

Area No. 16 Utilities Waste Water Treatment

Area No. 17 Utilities Diesel Storage

Internship ’10 Report (Production Unit) 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 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.

10) A good standard of housekeeping shall be maintained at the plant.

11) Off-The-Job safety shall be promoted among employees and their families.

12) Employees are expected to maintain pollution free environment and hygienic conditions

throughout the plant.

Internship ’10 Report (Production Unit) C

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.

9) Visitors are not allowed to enter the operating areas unless approved by competent

authority and guided.

10) Vehicle entry in operating areas is forbidden except under a valid permit.

11) Observe traffic rules.

12) All hazardous and unsafe conditions should be rectified by the areas themselves; safety

section is an audit and advisory function.

Internship ’10 Report (Production Unit) D

Appendix III

Process Flow Diagrams

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

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

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

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

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

Figure 24 PFD (Urea) ............................................................................................................... J

Figure 25 PFD (Ammonia): Front End ..................................................................................... K

Figure 25 PFD (Ammonia): BackEnd ....................................................................................... L

Internship Report (Production Unit) E

FIGURE 19 PFD (UTILITY): WATER PRE-TREATMENT I

Internship ’10 Report (Production Unit) F

09-ME-926

Clarified Water Basin

V-6 V-7

09-MP-926-B09-MP-926

V-8 V-9

V-11

P-13

09-MP-902-B09-MP-902-A

V-12 V-13

V-14V-15

09-MP-923-A 09-MP-923-B 09-MP-923-C

V-16 V-18 V-19

V-20 V-21 V-22

09-V-920-A-D

09-SD-14

V-24

09-SD-16

09-SD-11

09-SD-12

09-LIC-02

Filt

ere

d w

ate

r to

T-9

20

09-SD-15

HLA-03

LlA-04

L

09-LIC-01

09-T-920

Filtered water tank

Vent

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

BMR

Make up water to E-800-A-J

K-920

MK-920

09-ME-926 Clarified Water Distribution System

Prepared by AYAZ

Reviewed by MF

Utilities FFC MM

TUBE WLL WATER

Tube Well Water

V-40

FIGURE 20 PFD (UTILITY): WATER PRE-TREATMENT II

Internship ’10 Report (Production Unit) G

FIGURE 21 PFD (UTILITY): WATER TREATMENT

Internship ’10 Report (Production Unit) H

FIGURE 22 PFD (UTILITY): INSTRUMENT AIR PLANT

Internship ’10 Report (Production Unit) I

FIGURE 23 PFD (UTILITY): NATURAL GAS STATION

Internship ’10 Report (Production Unit) J

FIGURE 24 PFD (UREA)

Internship ’10 Report (Production Unit) K

FIGURE 25 PFD (AMMONIA): FRONT END

Internship ’10 Report (Production Unit) L

FIGURE 26 PFD (AMMONIA): BACK END

internship report at fauji fertilizer company

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