Vocational Training Report

Indian Farmers Fertiliser CooperativeKalol Unit

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Vocational Training Report

PANDIT DEENDAYAL PETROLEUM UNIVERSITY,

School Of Petroleum Technology,

Raisan, Gandhinagar-382007.

Submitted by,

Daxit Akbari-14BPE004

BACHELOR OF TECHNOLOGY

IN

[PETROLEUM ENGINEERING]

Training Period :-26th December 2016 to 10th January 2017

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ACKNOWLEDGEMENT

It’s really a matter of pleasure for me to submit this vocational training report at the end of training period from 26.12.2016 to 10.01.2017 at IFFCO-Kalol Unit.

At this moment, I am very thankful to INDIAN FARMERS FERTILISER COOPERATIVE LTD. (IFFCO)-KALOL UNIT for providing me a wonderful chance of working in company. I would like to show my deep gratitude towards the people who made it possible for me to have this training. I would like to present my heartiest thanks to JGM(Technical) O P Dayama sir and Senior Manager-Training, for accommodating in the plant and helping me through the planning of my internship. I would like to express my sincere gratitude to Mr. Vitthalbhai Radadiya – Director IFFCO, without whose support, I would never have got the internship in first place. I would also like to thank all the Engineers and Technicians of IFFCO-Kalol, without their boundless cooperation and help I would have not been able to obtain such vast knowledge and information and to complete this report. I express gratefulness to all for their cooperation and support.

Lastly, I thank all others, especially my co-trainees and my family members who in one way or the other helped me in successful completion of my work.

Thank you.

Daxit Akbari

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ABSTRACT

Indian Farmers Fertiliser Cooperative Limited (IFFCO) was established on 3rd November, 1967 as a multiunit cooperative organization of board objectives of augmenting fertilizer production, ensuring fertilizer availability at farmers door step, strengthening cooperative fertilizer distribution system and educating training and guiding the farmers for improving agriculture productivity. IFFCO the world’s largest cooperative company maintained its place in the first 100 by securing 53 rd

rank among Fortune’s 500 companies in India in 2015.

Commissioned on Nov.05, 1974 Kalol was IFFCO’s second big production facility and the most efficient. It is also the mother unit of IFFCO. IFFCO-Kalol fertilizer unit is based on the natural gas supply from Reliance Industries, located at about 18kms away from the capital of Gujarat, Gandhinagar.

The report mainly consist of various plants Ammonia plant, Urea plant, Utilities consisting of Cooling Tower, Demineralization (DM) plant, Inert gas-plant air and instrument air production unit, Steam generation plant (BHEL-Boiler), Offsite include Narmada Water Treatment plant, Effluent Treatment plant(ETP), Ammonia Storage, Bagging and Material Handling unit. The plant works on maximum recovery basis and has minimum effluent discharge as used in horticulture site.

IFFCO-Kalol has three ammonia storage tanks which is used as a backup for urea generation and also supplies the liquid ammonia at Kandla unit of IFFCO. The IFFCO- Kalol urea and ammonia plant is based on technology of M/S Stamicarbon, M/S Haldor Topse, M/S Snamprogetti,

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M/S Kwellog. Thus IFFCO-Kalol is one of the finest and the most efficient plant producing urea fertilizer in India.

Table of content

No. Subject Page No.

1 Introduction 6

2 Fire and safety 8

3 Ammonia Plant 9

4 Urea Plant 17

5 Utility 27

6 Offsites 35

7 Conclusion 39

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INTRODUCTION

Indian Farmers Fertilizer Limited also known as IFFCO is the world’s largest Fertilizer Cooperative Federation based in India. The Indian Farmers Fertiliser Cooperative Limited (IFFCO) was registered as a multiunit co-operative society, under the co-operative society’s action November 3, 1967. IFFCO, a pioneer in the cooperative sector, has been making a steady progress in the realms of fertilizer production, capacity utilization and rendering services to the farming community.

The number of co-operative societies associated with IFFCO has risen from 57 in 1967 to 40,000 at present. On the enactment of the multistate cooperative societies act 1984 & 2002, the society The is deemed to be registered as Multistate Cooperative Society.

IFFCO’S five modern fertilizer plants at Kalol and Kandla in Gujarat and Phulpur and Aonla in Uttar Pradesh and Paradeep in Orissa have a total annual production capacity of 56.63 lakh tones of fertilizer. The annual production capacity of five plants is given below. IFFCO has retained 7th Rank in the Business Standard ranking in 2016 out of 200 listed companies. Iffco has been ranked 53rd in fortune 500 list in 2015.

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IFFCO KALOL UNIT

The IFFCO Kalol Unit, spread over on 96 hectares of land, is located 26 kms away from Ahmedabad on the Ahmedabad Mehsana state highway and is 18 kms away from the capital of Gujarat- Gandhinagar. The unit started commercial production in April’1975. The unit consists of plants to produce ammonia, urea, liquid Ammonia stored at -33 C along with offsite facilities. Originally the 910 tpd ammonia plant was based on natural gas steam reforming process of M/s. M.W. Kellogg, USA and 1200 tpd urea plant was based on CO2 stripping process of M/s. Stamicarbon, The Netherlands. Both the plants have been revamped in 1997 to enhance capacities to 1100 tpd ammonia and 1650 tpd urea. The Natural gas (NG) available in the vicinity of the unit is supplied by Reliance Industries, GSPL, RGPTIL, and KG D6 Basin. Associated gas and LSHS are used as fuels. Water is supplied by Narmada Reservoir at Jaspur which is treated at Narmada Water Treatment Plant and is used in various plants at IFFCO-Kalol, the bore wells are currently not operated which were used earlier installed around the unit. Power is supplied by Gujarat Electricity Board (GEB) and UGCVL.

Consumption of inputs for the production of 1100 tonnes of ammonia 1650 tonnes of urea every day are given below.

Natural gas : 450,000 Sm3/dayAssociated gas : 200,000 Sm3/dayWater : 18,000 m3/dayLSHS : 140 tonnes/dayPower : 8,500 KVAChemicals : 60 tonnes/day

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PRODUCTION PERFORMANCE

The production records for all four units are excellent. Since inception, the capacity utilization achieved is always higher than the national average IFFCO has won several awards for the Fertilizer Association of India (FAI), National productivity Council and national and international safety councils for outstanding production performance and in safety measures.

Introduction to IFFCO, kalol unit :

The IFFCO Kalol Unit , spread over on 96 hectors of land is located 26 kms. away from Ahmedabad on the Ahmedabad Mehsana state highway. The unit started commercial production in April 1975. The unit consists of plant to produce ammonia, urea, liquid carbon dioxide and dry ice along with offsite. Originally the 910 tpd ammonia plant was based on natural gas steam reforming process of M/s. M.W. Kellong, USA and 1200 tpd urea plant was based on co2 stripping process of M/S Stamicarbon, The Netherlands. Both the plant have revamped in 1997 to enhance capacity to 1100 tpd ammonia and 1650 tpd urea. RLNG is used as feed stock for ammonia and associated gas as fuel. Water is supplied from Narmada Canal from Jaspur. Power is supplied by GEB.

Various Plants:

Ammonia Plant :The plant is being designated to produce 1150 metric-tonnes of ammonia per day based on M.W. Kellogg Steam Reforming Process of USA. RLNG is used for ammonia production is supplied by Reliance Petrochemicals. From total production, about 950 metric-tonnes ammonia per day is used in the urea plant and remaining is stored in atmospheric storage tank.

Urea plant : The 1650 metric-tonnes per day plant is based on Stamicarbon CO2 Stripping processs engineered by Humphreys and Glasgow, U.K. The main raw material ammonia and carbon dioxide are from ammonia plant.

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Utility plant : (I) Water Treatment Plant (II) Cooling Towers (III) Air Compressor and Inert Gas Generation (IV) Steam Generation

Offsite plant :

(I) Storage Tanks (II) Narmada Water Treatment Plant (III) Effluent Treatment Plant

Organizational structure :

Head office of IFFCO is located at New Delhi. It houses corporate staff function as: (I) Engineering Service Division (II) Management Service Division (III) Finance and Accounts (IV) Personnel and Administration (V) Marketing

List of plant and capacity:

Process Units :

Ammonia : 1160 Tons / Day

Urea : 1650 Tons / Day

Offsite & Utilities :

Water Treatment plant : 2570 Tons / Day

Steam Generation Plant : 1920 Tons / Day

Instrument and Plant Air : 1800 Nm3 / hr

Cooling Tower : 22900 Tons / Day

Raw Water Storage : 2600 m3

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Ammonia Storage : 15000 Tons

FIRE AND SAFETY UNIT

Safety overview:-

The Significance of Safety & Health in chemical industries has been a vital issue in achieving productivity and edge in the competitive world. IFFCO’s continuous effort to implement safety, health and environment systems in the organization have been appreciated and recognized by several government and safety regulating bodies. Material Data Sheet (MSDS) gives the detailed information regarding the potential hazards and safety measures in every Industries. As per the Government norms IFFCO-Kalol follows each and every guidelines mention by the Government of India and Gujarat.

Possible threats :-

Dangerous Materials. Hazards of Pressure Vessels. Hazardous chemical reactions. Hazards of unit operations. Flammable gases, vapors and dust hazards. Hazards due to instrument failure. Hazards due to corrosion.

Fire and Safety Equipments

Types of safety equipments are at IFFCO-Kalol:- Hard Hat (Safety Helmet) Safety Shoes & Goggles Gas Detectors

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Eyewash/Ammonia wash station Ear Protection Dust Masks & Respirators Safety Signs Flashlights Lightning Arrestors First Aid Kits Welding Equipment Wind direction indicators

Ammonia Manufacturing Plant

Ammonia plant of IFFCO-Kalol was commissioned in 1974 based on natural gas steam reforming process which follows following stages one by one.

Natural gas desulfurization Catalytic Steam Reforming

o Primary steam reformingo Secondary steam reforming

Carbon monoxide shift (HT & LT) Carbon dioxide removal Methanation Ammonia synthesis

Flow diagram of ammonia synthesis by air reforming process:-

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NATURAL GAS SUPPLY AND DESULPHURIZATION:-

The natural gas, which is used as feedstock for ammonia plant is supplied at the battery limits by Reliance/GSPC/K6 Godavari Basin from their gas fields. Two turbine driven centrifugal compressors of adequate capacity in series are installed to boost up the pressure of natural gas upto 39 kg/cm2g.Control valve and relief valve are given in series if there is any kind of abnormality in pressure rise for safety and pressure regulation. Natural gas is then split into two streams as Feed Stock and Fuel Stock. Natural gas is then sent to Desulphurizer. Natural gas contains sulphur compounds in the form of sulphides, disulphides, mercaptan sulphur and thiophenes etc. which are poisonous to the catalysts used in ammonia plant. The process of removing these sulphur compounds is called desulphurisation. The process employed is adsorption and adsorbent used is activated carbon catalyst. The naphtha performer is in decommissioning stage as the plant now operates at 100% Natural gas feed supply.

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REFORMING (PRIMARY, SECONDARY REFORMING & WASTE HEAT BOILERS):-

Reformer consists of three parts as follows:-1. Primary Reformer2. Secondary Reformer3. Waste heat Boiler

PRIMARY REFORMING:-

The natural gas after removal of sulphur compounds in Desulphurizer enters feed preheat coil in the convection section of primary reformer furnace. The natural gas temperature is raised by the flue gas coming out of the convection zone of the furnace. Then natural gas is mixed with superheated steam. The mixture of natural gas and steam mixed feed preheat coil in the convection zone. From outlet of mixed feed pre heat coil, reformer feed goes to primary reformer. The reformer feed then passes through the catalyst packed reformer tubes. There are 336 tubes arranged in eight rows of 42 tubes each

As the reaction is endothermic i.e. it absorbs heat, the heat is supplied by burning mixed fuel gas as fuel in top fired 126 top fixed arch burners. The catalyst used in the primary reformer is nickel based. Top portion of the tubes is filled with potash based nickel catalyst. Primary reformer exit stream is taken to secondary reformer.The reactions taking place can be written as follows:-

CnH2n+2 + nH2O n CO + (2n + 1) H2, H > 0

CH4 + H2O CO + 3H2 H = 49.28 kcal/kgmole

CH4 + 2 H2O CO2 + 4H2 H = 39.44 kcal/kgmole

CO + H2O CO2 + H2 H = - 9.82 kcal/kgmole

SECONDARY REFORMER:-

The partially reformed gas from primary reformer enters the secondary reformer Process air supplied by process air compressor is preheated in steam air preheat coil.

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The temperature of gas inlet to secondary reformer is around 7860 C .The parts of H2 and other combustible gases in the process gas burn with oxygen, leaving the nitrogen required to make ammonia. The amount of air is fixed by the nitrogen requirement for the ammonia synthesis.. The reaction with air in secondary reformer (combustion zone) is as follows:-

2H2 + O2 + 3.715 N2 2H2O + 3.715 N2 + Heat

2CH4 + 3.5 O2 + 13.003 N2 CO2 + CO + 4 H2O + 13.003 N2 + Heat

The reaction is exothermic; temperature is around 12350 C. Catalysts used are high temperature resistant chromia and high activity nickel at the top and bottom respectively. The methane steam reforming reaction in secondary reformer is same as that given for primary reformer.

WASTE HEAT BOILERS:-

Reformed gas with process steam at 9350 C from the bottom of secondary reformer passes through the shell side of two parallel flow refractory lined water jacketed primary waste heat boiler. Then the gas passes through the tube side of secondary waste heat boilers in which it is cooled to the desired high temperature shift converter inlet temperature. These waste heat boiler generate the major portion of the steam required to operate the unit. The temperature of the gases reduced to 366o C. 105 ata steam is generated by secondary reformer heat in waste heat boiler.

WATER GAS SHIFT REACTION:-

(a) High temperature shift conversion:-

The reformed gas enters the high temperature section of shift converter and flows through the catalyst bed. The catalyst used in high temperature shift converter is copper promoted iron oxide catalyst in reduced state. The following reaction takes place in shift converter:-

CO + H2O CO2 + H2 H = - 9.82 kcal/kgmole

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As indicated by this equation, most of the carbon monoxide is converted to carbon dioxide gaining an additional mole of hydrogen per mole of carbon monoxide.

(b) Low temperature shift conversion

The gas coming out of high temperature shift converter still contains about 3.36 % carbon monoxide, which should be reduced to within tolerable limit before sending the gas for CO2 removal and Methantion.This is accomplished in low temperature shift converter. The gases leaving from HTS goes to Low temperature Guard Shift Convertor. Low temperature shift converter contains high copper catalyst. The shift reaction is same as in high temperature shift converter. LTS inlet gas temperature must have 200 C superheat to avoid any chances of condensation. Condensation of LTS inlet gas damages the catalyst physically, reduces the strength and activity of the catalyst. LTS catalyst is fixed and costlier in nature which cannot be removed during regular plant operation so direct use of gas from HTS to LTS can damaged the catalyst present in LTS. The LTS-Guard also contains copper catalyst but can be changed during regular plant operation.

CO2 ABSORPTION AND STRIPPING:-

In this section the bulk of CO2 in the raw synthesis gas is removed by absorption, using 40% aqueous activated methyl diethanol amine (a-MDEA) solution {CH3-N(CH2-CH2-OH)2}, at relatively high pressure and low temperature. The absorption of CO2 involves the reaction of dissolved CO2 in water with a-MDEA to form a loose chemical compound which can be easily dissociated at higher temperature and lower pressure. Following reaction takes place:-

CO2 + H2O H2CO3

The raw synthesis gas at a pressure of 27.3 kg/cm2g and temperature of 630 C containing about 18 % dry volume of CO2 is introduced at the bottom of CO2 absorber. Absorber is a cylindrical tower fitted with twenty perforated sieve trays one above the other spaced at equal distance. Lean a-MDEA solution

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from CO2 stripper bottom is cooled in a-MDEA solution exchanger and then in a-MDEA solution cooler by rich a-MDEA and cooling water respectively. a-MDEA circulation pumps introduces the lean a-MDEA solution over the top tray of the tower. Solution flows downwards, counter current to the gas flow.

Almost all the CO2 is absorbed by the solution, leaving only small traces of CO2 in absorber outlet gas. The gas before leaving the tower passes through a demister pad to remove the entrained solution, if any.

Rich a-MDEA solution from the bottom of absorber is sent to CO2 strippers for regeneration. Strippers operate at a pressure of 0.74 kg/cm2g and temperature of 1180 C at the bottom. Rich a-MDEA solution is heated by heat exchange with the lean solution coming from the bottom of strippers, in a-MDEA solution exchangers and then splits into equal stream as feed to CO2 strippers through control valves.

CO2 stripper towers are fitted with seventeen perforated sieve trays each spaced equally one below the other. The solution enters above the top tray. The function of CO2 strippers is regeneration of rich a-MDEA solution by liberating CO2 absorbed in it, so that the solution can be reused in absorber. The solution in the stripper bottom is heated in reboilers.

The solution from strippers while passing through the tube side of these reboilers is heated to 1180 C and by thermosyphoning\ the vapor solution mixture returns to strippers from the top of reboilers. As the vapors rise through the trays, the rich a-MDEA solution together with the reflux pumped from CO2 stripper reflux drum comes in contact with it and condenses the vapors. The CO2 thus stripped off in strippers along with water vapor and a-MDEA vapor leave strippers. These are cooled by cooling water in CO 2

stripper condensers.

The CO2 (by product of ammonia plant) is sent to urea plant and balance if any, is vented by to atmosphere. The lean a-MDEA solution form the bottom of strippers is reused after cooling, for absorption of CO2 in absorber.

METHANATION:-

For ammonia synthesis a very pure gas mixture of H2 and N2 in the ratio of 3:1 (by volume) is required and the small amounts of CO2 and CO are poisonous to

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the ammonia synthesis catalyst. These oxides are removed by converting them into methane in Methanator by a highly active nickel based catalyst in presence of H2. This step is known as Methantion. Methane has no action on the ammonia synthesis catalyst, but it accumulates in the synthesis loop as inert. Methantion reactions are given below:-

CO + 3H2 CH4 + H2O H = - 49.28 kcal/kgmole

CO2 + 4H2 CH4 + 2H2O H = - 39.44 kcal/kgmole

Both these reactions are highly exothermic, and hence extreme care is to be observed while operating Methanator. The unit is properly protected with high temperature alarms and shut off systems. Methanator vessel is filled with nickel catalyst.

The hot Methanator outlet gas, which is called as synthesis gas is cooled by exchanging heat with boiler feed water, Methanator effluent cooler and finally in suction chiller to 80 C where ammonia from second stage refrigerant drum is used as cooling media. The gas then flows to synthesis gas compressor suction.

AMMONIA SYNTHESIS:-

The pure synthesis gas mixes with the recovered hydrogen from the purge gas recovery plant. The mixture is then compressed in a turbine driven two case centrifugal compressors. Recycle gas mixture consisting of ammonia (14.75 % by volume) and unreacted reactants from synthesis converter is admitted in the last wheel of the second case and mixes with synthesis gas mixture (make up gas as it is called) and undergoes final stages of compression to approximately 137 kg/cm2g and temperature of 65.30 C. The compressor discharge gases are then cooled. Dry basis (vol. %) are, H2: 60.48, N2: 20.17, NH3: 11.68, CH4: 5.00 Ar: 67

The ammonia synthesis reaction taking place at elevated temperature and pressure in presence of a promoted iron catalyst is as under:-

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N2 + 3H2 2NH3 H700 K = - 12.55 kcal/kgmole

As the reaction is exothermic, a rise in temperature lowers the equilibrium conversion of ammonia and at the same time accelerates the reaction rate. If reaction is near equilibrium, rise in temperature will lead to decrease in conversion and vice versa.

Since synthesis of ammonia involves a decrease in volume, rise in pressure will favor reaction equilibrium. At the same time reaction rate is also accelerated by increase in pressure. Hence higher pressure favors conversion.

Other factors which influence operation of the converter include circulation rate, ratio of H2: N2 in the feed gas, inert content in the loop, percentage of ammonia into converter feed and poisoning and ageing of catalyst. All these factors are inter-dependent and a change in one will have effect on others. Only experience will dictate what steps should be taken to compensate the change so that the system remains in good control.

REFRIGERATION:-

The primary purpose of the refrigeration system is to make available liquid refrigerant ammonia at different temperature which is required to circulate through chillers for condensing product ammonia from converter feed. Further it is also required:-

To cool makeup gas for separation of water at the suction and interstage of compressor.

To condense and recover liquid ammonia from purge and flash gases. To cool the product run down to -33 C. To provide refrigeration duty in refrigerant cooler of PGR plant. To degas the inert from product ammonia.

AMMONIA:

Physical and Chemical properties:

At Atmospheric temperature & Pressure Ammonia is a sharp colorless gas.

Formula : NH3

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Specific Gravity : 0.682 M.W. : 17.03 gm/mole Critical temperature : 132.14 °C Auto ignition temperature : 651 °C Boiling Point : -33.3 °C Freezing point : -77.7 °C Nature : Alkaline Odor : Colorless NH3 is very soluble in cold water and NH4OH. NH3 is readily released from liquid Ammonia with increase in

temperature.

Hazardous Properties :

When Ammonia stored in closed container NH3 exert to vapor which increase rapidly with rising temperature.

NH3 will explosive mixture with air and Oxygen. Moist NH3 will react rapidly with Cu & Zn. The use of the Hg in contact with NH3 should be avoided since under

certain condition explosive chemical compounds resulting. NH3 is an irritating gas & will affect muscles, membrane & eye.

Hazardous identification :

Color : colorless Physical form : gas, liquid Odor : pungent odor Physical hazards : Containers may rupture or explode if exposed to heat

First aid measures :

Inhalation :

If adverse effects occur, remove to uncontaminated area. Give artificial respiration if not breathing. If breathing is difficult, qualified personnel should administer oxygen. Get immediate medical attention.

Skin contact :

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Wash skin with soap and water for at least 15 minutes while removing contaminates unclothing and shoes. Get immediate medical attention. Thoroughly clean and dry contaminated clothing and shoes before reuse. Destroy contaminated shoes.

Eye contact :

Immediately flush eyes with plenty of water for at least 15 minutes. Then get immediate medical attention.

Ingestion :

Do not induce vomiting. Never make an unconscious person vomit or drink fluids. Give large amounts of water or milk. When vomiting occurs, keep head lower than hips to help prevent aspiration. If person is unconscious, turn head to side. Get medical attention immediately.

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UREA MANUFACTURING PLANT

Urea plant at IFFCO-Kalol was commissioned in 1974 based on CO2 Stripping process.

The Urea process consists of the following steps.

1. CO2 supply and compression 2. NH3 supply and pumping 3. Reaction/High pressure synthesis 4. Low pressure/Recirculation system 5. Evaporation and Prilling System6. Urea hydrolyser and Desorber7. Steam and condensation

CO2 supply and compression :-

The CO2 gas is available from ammonia plant at normal pressure of 0.14 to 0.22 kg/cm2g and at a temperature of 50° C to 60° C. This gas is cooled and saturated in CO2 spray cooler with spray water. CO2 and water flows counter currently through packed bed of polypropylene pall rings for cooling. A demister pad above the distribution tray is provided to prevent the water carryover along with exit CO2 from spray cooler.

Water from the bottom of the spray cooler is sent to the cooling tower by CO2

spray cooler sump pump. The exit saturated CO2 with water vapour enters the CO2 knock out drum where the moisture is knocked out and drained.

Anticorrosion air is injected into the cooled CO2 stream with the help of anticorrosion air blowers. The air is required to maintain the oxygen level of 0.60 % in the CO2 stream for HP equipments passivation to prevent corrosion. The CO2 leaving knock out drum is compressed in Hitachi make CO2

centrifugal compressor.

NH3 supply and pumping :-

Liquid ammonia directly from ammonia plant enters the urea plant battery limit at 20 kg/cm2a and 40° C. The alternate source for ammonia supply is

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from the atmospheric ammonia storage tank. The cold liquid ammonia is preheated to 40° C in the ammonia pre heater.

Liquid ammonia from filter outlet enters the ammonia suction vessel which serves the purposes of providing a suction volume for HP ammonia pumps and acting as a pulsation dampener. The liquid ammonia from the ammonia suction vessel is pumped at reaction pressure of 153 kg/cm2a. Out of total ammonia discharged by pumps, 90-95 % ammonia goes to HP Carbamate condenser and 5-10% goes to autoclave.

Reaction/High pressure synthesis (HP system):-

a) HP stripper

CO2 gas with 0.60 % oxygen and inert discharged from CO2 compressor at 157 kg/cm2a and 115 to 120° C enters the stripper. Autoclave overflow line leads to HP stripper at the top channel. The liquid dividers are fitted over each tube having ferrule. Each ferrule in the liquid divider has three holes each of 2.6 mm diameter through which the liquid flows into the tubes. This exchanger acts like a falling film counter-current heat exchanger. The efficiency of the exchanger depends on the formation of liquid film. Liquid distribution in the tube is very important. Liquid starvation in tube may happen when there is loss of liquid level in autoclave or blockage of ferrules holes. Stripper tubes under this condition will be over heated resulting in heavy corrosion and tube failures. CO2 while rising through the tubes picks up heat from falling solution and strips off NH3 and CO2 from the Carbamate. From HP stripper top channel CO2 along with liberated NH3 is taken to HP Carbamate condenser. Saturated steam at 21.8 kg/cm2g and 216° C is introduced at the shell side of the HP stripper to provide the heat required for stripping.

Urea Carbamate solution is collected at the bottom channel of the HP stripper. This solution is let down from 153 kg/cm2g to 2.3 kg/cm2g across the level control valve. It is imperative that to maintain the stripper working efficiency, both gas and liquid flow through each tube must be continuous and even.

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b) HP condenser

The vapour (NH3 & CO2) liberated from the HP stripper flows upwards to the top channel of HP Carbamate condenser below the packed bed. Liquid ammonia from HP ammonia pump at a pressure of 153 kg/cm2a and 45° C enters the top channel. HP stripper exit gas is rich in CO2 and the NH3/CO2

mole ratio is around 1.7. The presence of 2.5 % water and slightly higher system pressure makes the optimum mole ratio to around 3.0.

Dilute Carbamate solution generated in LP system is pumped with HP carbamate pumps to HP condenser and HP scrubber. Dilute carbamate line joins the inlet liquid ammonia line to HP condenser. About 65 % of the carbamate solution is fed to HP condenser. The remaining carbamate is fed to HP scrubber. Carbamate solution joins the liquid ammonia stream and then enters HP condenser. The mixed stream flows through the packed bed, located above the liquid distribution tray. Some of the vapours (NH3

and CO2) enter the packing and a part of it is condensed within the packing. Uncondensed vapours flow through the tubes and are condensed to carbamate.

Boiler feed water/ condensate enters the shell side from 4 ata steam drum through the four down comers and generated steam rises up through the steam risers and enters the steam drum. Liquid carbamate solution and uncondensed gases leaves HP condenser from separate nozzles at the bottom and enters the bottom channel of autoclave.

At the operating condition prevailing in the HP condenser, the rate of carbamate formation is proportional to the rate of removal of heat of exothermic reaction. The pressure prevailing in the steam drum should not be brought down below a certain value otherwise the crystallisation temperature of carbamate (153° C) would be reached. 90 % (v/v) of the vapours condense in high-pressure condenser and the remaining 10 % are condensed in autoclave thereby supplying necessary heat for urea formation from carbamate

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C) Autoclave (Reactor)

The carbamate solution and uncondensed NH3 and CO2 from the HP carbamate condenser are introduced at the bottom of the autoclave. A part of liquid ammonia from HP ammonia pump is also introduced at the bottom of the autoclave. Quantity of ammonia required to be introduced into the autoclave is determined from the process condition and plant load. Autoclave receives liquid ammonia, carbamate solution and uncondensed NH3, CO2, O2 and inert from HP condenser and carbamate solution from HP scrubber. All the four streams join at four different nozzles at the bottom of the autoclave and rises to the top through eleven sieve

trays. Liquid mixture of urea, carbamate and water overflows to the down comer to the HP stripper.

A radioactive source (Cobalt -60) is provided for level measurement of autoclave. Loss of liquid level in autoclave will evidently create a number of problems in the system. Due to loss of liquid level, CO2 will flow in reverse direction to autoclave via down comer and pressure rise will be very quick and HP condenser temperature will fall sharply.

The inert and unconverted NH3 and CO2 exit the autoclave through an overhead line to HP scrubber. HICV, located on the autoclave gas exit line, controls the autoclave pressure and consequently high-pressure system in emergency. To protect high-pressure system from over pressurisation, relief valves set at 161 ata are installed on autoclave top exit gas line.

d) HP scrubber

Uncondensed NH3 and CO2 and non-condensable from the reactor top enter the bottom of high pressure scrubber. Dilute carbamate through HP carbamate pumps fed to HP scrubber condensing media in the shell side. NH3 and CO2

get condensed while bubbling up through the liquid head. A small amount of uncondensed NH3 and CO2 and the inert leave the HP scrubber through inert vent valve to LP absorber. CO2 is injected above packed bed for purging so as to prohibit any explosion that may occur due to presence of H2.

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Heat of carbamate formation is removed by a closed condensate circulation system. Carbamate solution formed overflows through a nozzle located above the ‘U’ tube bundle to autoclave.

LP absorber and scrubbing system/LP Recirculation System

Uncondensed NH3, CO2 and non-condensable from the HP scrubber enter the bottom of LP absorber. NH3 and CO2 get scrubbed with lean ammonia water while rising up through the two packed beds. The lean ammonia water is supplied by process water pump from lean ammonia water tank. A small amount of uncondensed NH3, CO2 and the inert leave the LP absorber to ammonia scrubber. Final scrubbing of the vapours is achieved in ammonia scrubber with lean ammonia water or DM water before being vent to atmosphere.

It has following stages in which the process is carried out:-

(a) Rectifying column / separator

The urea carbamate solution from the HP stripper is let down to 3.3 kg/cm2a across stripper level control valve. As a result of pressure letdown, part of the carbamate in the solution is vaporised to NH3 and CO2 and solution gets cooled from 170° C to 120° C. The liquid vapour mixture flows into the top of rectifying column / separator. The liquid vapour mixture is sprayed over the packed bed of rasching rings through a nozzle and spray breaker in rectifying column.

(b) LP carbamate condensers and separator

The overhead vapours leaving from rectifying column are introduced at the bottom of falling film type LP carbamate condenser. Part of the NH3

and CO2 are condensed to form ammonium carbamate. Lean ammonium carbamate formed in the flash tank condenser is introduced in to the gas inlet line of the LP carbamate condenser through a sparger by lean carbamate pumps. The carbamate formed in reflux condenser of hydrolyser system is also taken top of LP condenser. Provision is also made to introduce measured quantity of liquid NH3 to maintain NH3/CO2 mole ratio. Heat of condensation is removed by condensate circulation system.

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Carbamate solution from LP carbamate condenser overflows into the LP carbamate separator, which also acts as a suction vessel for HP carbamate pumps. The pressure control valve on gas exit line to atmospheric scrubber and effectively controls the recirculation system pressure by sending vapors to the atmospheric vent scrubber for further recovery of NH3.

(c) Carbamate solution recycle

Carbamate solution from LP carbamate separator is recycled to HP synthesis section via HP carbamate pumps. Carbamate solution at 2.3 kg/cm2g pressure and 74.2° C is pumped by two of the HP carbamate pumps. Around 35 % of solution is pumped to HP scrubber and the rest to HP carbamate condenser. Carbamate pumps are reciprocating pumps driven by variable speed motors via a gearbox.

(d) Flash tank condenser

Vapours from the flash tank separator flows to flash tank scrubber where any residual urea, NH3 is scrubbed with ammonia water supplied by urea recovery circulation pumps. The vapours leaving the scrubber are sent to flash tank condenser where remaining NH3 and CO2 are condensed by cooling water to form lean carbamate solution. Heat of reaction and latent heat of water formation is removed by circulating cooling water in the tube side of the condenser. Vapours leaving the flash tank condenser are sent to atmospheric vent scrubber for further recovery of NH3 or can be removed by the flash tank ejector when flash tank is operated under vacuum when pre evaporator section is bypassed. 4 ata steam is used in the ejector. The air in bleed isolation valve is provided to the flash tank condenser for releasing the vacuum when Prilling section is shut down

(e) Pre evaporator

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The urea solution from the flash tank separator at about 104° C and 1.06 kg/cm2a pressure is flashed to pre evaporator, which is maintained at 0.40 kg/cm2a vacuum pressure. Urea solution is heated up to 98.6° C in two separate heat exchangers, which are parts of pre evaporator. Temperature of the exit urea solution is controlled by 4 ata steam control valve provided on 4 ata steam inlet line. Exit urea solution at concentration of 82.6 % (w/w) and temperature of 98.6° C is drawn to urea solution storage tank.

(f) Urea solution storage tanks

Two urea solution storage tanks are installed to receive urea solution tank. Urea solution (82.6% w/w) from the pre evaporator is received in urea solution tank for onward pumping to the evaporator. Urea storage tank is maintained under atmospheric pressure. Urea solution tank also receives recycle solution of evaporation section during start-up and urea dust dissolved solution from prill cooling system and bagging and from material handling plant via prill cooling system

(g) Ammonical Water Storage Tank

Ammonical Storage Tank is provided where the condense gases from carbamate condensers, rectifying column, scrubber etc are condense and stored in Ammonical Water Tank where the concentration is of carbamate solution and ammonia. This Ammonical water is recovered by passing through Hydrolyser and Desorber and is reutilized. Thus Ammonical Water Storage Tank is used for the 100% recovery basis in Urea plant.

Evaporation and Prilling System:-

Urea solution having a concentration of 82.6 % is pumped from the urea solution tank to the first evaporator separator by urea solution pump. The evaporator separator operates under vacuum at 0.31 kg/cm2 a. Urea solution is heated in the shell and tube type heat exchanger with urea solution flowing in the tubes and 4 ata steam on the shell side. The urea solution is heated from 98.6° C to 130° C to achieve urea solution concentration of 95%. The urea

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solution from the climbing film single pass evaporator flashes into the separator mounted directly on the evaporator. The water vapour together with some ammonia is separated in the separator by an impingement cone and baffle arrangement.

Urea solution at a temperature of about 130° C, having concentration of 95% (w/w) then flows from first evaporator to the second stage evaporator separator. Second stage evaporator is operated at a pressure of 0.03 kg/cm2a. In the low residence time single pass evaporator, the urea solution is further concentrated to over 98.5% urea

melt for Prilling. The urea solution flowing on the tube side is heated up to a temperature of about 140° C with 9 ata steam flowing on the shell side. The urea solution from the second evaporator flashes into the separator mounted directly on the evaporator. The overhead vapours from the evaporator separator are condensed and collected in ammonia water tanks.

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Prilling tower:-

Prill cooling system and material handling :-

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Urea prills after discharging from product conveyor flows into the fluidised bed cooler through inlet nozzle. Atmospheric air is supplied by inlet air fan for cooling.

During fluidisation on perforated plate of fluidised bed cooler, heat of hot prills is taken away by air and cooled urea prills at 55° C flows over the weir to discharge nozzle. Exhaust air along with some fines of prills and at temperature of about 70° C passes through the exhaust air nozzle to the dust removal system unit. Exhaust air is passed through cyclone separators to remove urea dust. After removing dust, almost clean air is exhausted to atmosphere by exhaust air fan through exhaust air chimney. The dust separated in the cyclone separators is collected in the three silos. From silo dust is transferred to belt conveyor with the help of rotary valves provided at the outlet of silos. All the silos are provided with vibrators to make the dust fall easier. Dust from the conveyor belt is transferred to dust dissolving tanks.

From the discharge nozzle of fluidised bed cooler, cooled prills at 55° C are discharged to product transfer conveyor through two link conveyors.

Neem Oil Coated Urea:-

Neem oil coated urea is used as the government is providing subsidy for so. Neem oil coated urea has been used as it has many advantages like the nitrogen decomposition in soil is less rapid compared to traditional urea and black marketing of urea also curbs down. Neem oil is added after the fluidized bed into the conveyor system and is transported to Silo where it is further transported to bagging unit and packed in 50kg bags.

Products :

(1) Urea

Product properties : State : Crystalline solid prills Chemical formula : NH2-CO-NH2 Molecular weight : 60

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Melting point : 132.7 C Specific gravity : 1.33 Hydrolyses very slowly in ammonia and carbon dioxide. Absorbs moisture from the air. Urea undergoes a number of reactions of heating about its boiling point. At 160 C, it decomposes to yield ammonium biuret and higher

condensation products. Longer the urea is held above its melting point, the further reaction

proceeds.

Urea specifications :

Total nitrogen : 46.3% by wt. Moisture : 0.3% by wt. Biuret : 0.9% by wt. Fe – content : up to 1.5 ppm

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UTILITY PLANTUtility plant consists of mainly:-

1. Steam Generation Plant (Boiler)2. Inert gas plant/Plant & Instrument Air3. Cooling Tower4. Demineralization plant (DM plant)

Steam Generation Plant:-

The modern steam generator is an integrated assembly of several essential components. Its function is to convert water into steam at a predetermined pressure and temperature. It is a physical change of state, accomplished by transferring heat produced by combustion of a fuel, to water. Commonly it is a constant pressure process. The steam generator is a pressure vessel into which liquid water is pumped at the operating pressure. After the heat has vaporized the liquid, the resulting steam is then ready either for delivery to the user or for further heating in a superheater.

At IFFCO-Kalol Plant, a BHEL make boiler of 80 t/h (net) capacity was commissioned on 5th October’1982 and is in operation since then.

The BHEL boiler is water tube type, bidrum, forced draft furnace. It is oil and/or gas fired boiler of 80 t/h capacity at 61.5 kg/cm2g pressure and 410+ 5º C temperature.

Steam:-

Steam is the vaporized form of water. The vapor is commonly visible as cloud escaping from the spout of tea kettle in which water is boiling. The water in the tea kettle produces 1600 times more volume in steam form.

These properties of steam, its ability to carry a large amount of heat and the large quantity of steam which can be made from a small amount of water, make steam an ideal substance for transferring heat conveniently and economically to every corner of the plant. Another property of steam is the way its volume varies with change in temperature and pressure of the steam.

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We take advantage of these properties by generating steam at high pressure to operate steam turbines, drive generator, compressor and pumps. The low pressure exhaust steam from the turbines is then used for process requirements.

Steam itself will not burn nor will it support combustion and this property of steam is utilized to purge or remove oil or gas or extinguish a small fire.

The intent of the ensuing discussions is to present the fundamentals and precautions encountered in steam generation. The fundamentals presented touch the basics of heat transfer and their respective contribution to steam generation, furnace details, material selection, fuels etc. The precautions mentioned pertain to feed water treatment in areas of oxygen removal, alkalinity and scale formation.

Inert gas plant and plant & instrument air plant:-

At Kalol plant, nitrogen (N2) is used as inert gas. The inert gas (IG) is almost dry and contains very low level of ‘active’ impurities since the inert gas will come in contact with various catalysts in ammonia plant in reduced condition. Ammonia plant also requires hydrogen (cracked gas) to reduce fresh charge of LTS catalyst. During the plant turnaround and shutdowns of ammonia plant the fresh catalyst can be reduced using the cracked gas and inert gas generated in inert gas generation plant, IG thereby saving around 6 to 7 days of startup time of ammonia plant. Also LTS catalyst can be heated with inert gas during plant start-up to reduce plant start-up time.

IFFCO Kalol has two independent inert gas generation plants for producing inert gas (nitrogen gas). In both the plants inert gas is produced by ammonia cracking process. Inert gas generation plant supplied by M/s. Wellman Incandescent was commissioned in 1975. The inert gas generation plant supplied by M/s. Indcon Polymech Ltd, (G-5501) was commissioned in 1994.

In the ammonia cracker, ammonia dissociates at 850 0C into hydrogen and nitrogen in presence of a nickel based catalyst.

2 NH3 (g) 3 H2 (g) + N2 (g) H = +10.96 kcal/g mol

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In combustion chamber, air is supplied so as to maintain O2 slightly less than the theoretical requirements for reaction with hydrogen to retain slight unreacted hydrogen in the gas leaving the combustion chamber. The combustion reaction is :

2 H2 (g) + O2 (g) + N2 (g) 2 H2 O (g) + N2 (g) H =-57.798 kcal/g mol In deoxo unit, the traces of oxygen react with hydrogen in presence of palladium catalyst.

2 H2 (g) + O2 (g) 2 H2 O (g) H =-57.798 kcal/g mol

Liquid ammonia from ammonia storage tank is received at 7 kg/cm2g pressure and – 330 C temperatures and is fed to shell side of ammonia vaporizer. Ammonia vaporizer is having a coil arrangement. In the tube side, hot cracked gas flows and provides heat for ammonia vaporization. Then vapor ammonia flows to the ammonia cracker which is electrically heated vessel containing a Ni-based catalyst. The ammonia dissociates into hydrogen and nitrogen in presence of Ni-based catalyst at around 850 C. The hot cracked gas from cracker after passing through the coil of the vaporizer enters the combustion chamber, where hydrogen is burnt with slightly less than stoichiometric quantity of air inside a water jacketed combustion chamber.

The gas leaving the combustion chamber passes into contact cooler, where demineralised water/raw water is used as the coolant. The water leaving the contact cooler contains traces of ammonia and goes to jacket cooling water pump pit.

The nitrogen after cooling passes to the inert gas surge drum for removal of water and then to the motor driven inert gas compressor where it is compressed to 7.0 kg/cm2g in two stages. The nitrogen gas then enters the de-oxo unit in which residual oxygen reacts with hydrogen in presence of palladium catalyst to give required nitrogen purity. Nitrogen from the de-oxo unit is cooled in shell and tube type after cooler, dried to -40 C dew point in a dryer unit and then stored in an IG receiver from where it is distributed to various consumption points.

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Plant and instrument Air:-

Compressed air is a major source of industrial power, possessing many inherent advantages. It is safe as well as economical, adaptable and can be easily transmitted. A compressed air plant considered in broader sense consists essentially of one or more compressors (each with necessary drive and controls), in-take air filter, inter cooler, after cooler, water separator, air receiver, inter connecting piping, dehumidifier and distribution network to carry air to the various points of application. The object of installing compressors and maintaining the compressed air system is to provide service air (plant air) and instrument air at the point of application in sufficient quantity and with adequate pressure for efficient operation of instruments, controls, air tools & appliances, on-line air masks and for emergency start-up of 0.860 MW diesel generation set in case its air compressor is not available.

Plant air and instrument air are the same except the moisture content. The instrument air is dried in dryer to achieve dew point of -40 ºC at atmospheric pressure. The compressed air is available through two sources i.e.

High pressure air available from the air compressor of ammonia plant. Reciprocating air compressors in compressor area of utility section.

The compressed air at around 7.0 kg/cm2g pressure is used as plant air and the header goes to all the consuming points. The compressed air after dehumidification process is used as instrument air. The instrument air at 7.0 kg/cm2g pressure is supplied to all consuming points mainly for instrumentation and control purpose.

The normal overall compressed air requirement in the plant is around 1800 Nm3/h which is touching to 3000 Nm3/h during peak demand. Instrument air receiver has a capacity, lasting approximately 5 to 7 min. in the event of compressors failure so that the plant can be shut down safely.All the compressors of utility section are integrated. Normally air is made available from process air compressor of ammonia plant and integrated with plant / instrument air.The plant air is supplied to:-

ammonia plant,

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urea plant, utility/off sites plant, workshop, bagging & material handling plant, on line air masks and Various local connections.

The instrument air is supplied to:-

Ammonia storage tank, Water treatment plant, Urea plant, Bagging and material handling plant. Steam generation plant, Effluent treatment plant, Cooling towers, Inert gas generation plants, CO2 compressors, Ammonia plant during plant shutdown and For emergency start-up of 0.860 MW diesel generating set when its

compressor is not available. The ammonia plant is self sufficient so far as its instrument air supply is concerned. During normal operation, ammonia plant does not need any instrument air from an outside source. However, when the process air compressor is not in operation, instrument air will be supplied to ammonia plant from the instrument air compressors of utility section.

Cooling Tower:-

Principle of cooling tower

The cooling tower is one type of heat exchanger which cools hot water with air. It is basically a tower containing treated wood as filling material. Filling material is piled up in the tower from the distribution basin. Water falls on the filling and breaks into fine droplets. The function of the filling (internals) is to increase the contact surface between the water and air. The filling at IFFCO -Kalol is replaced by V-shaped PVC bars having small slots from wooden

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splash bars and are arranged in such a way that the water entering the distribution trays near the top of the tower is repeatedly broken into fine particles as it descends through the tower. Fan mounted on top of the tower induces air into the tower through air inlet louvers, placed on either side of the tower. Across this air flow, water drops fall through fillings.

Types of cooling tower

Modern cooling towers are classified according to the means by which air is supplied to the tower and the method of contact between water and air. There are two types of cooling towers

Atmospheric and natural draft cooling tower. Mechanical draft tower.

The mechanical draft towers is subdivided into two types

Forced draft towers Induced draft towers.

Forced Draft Towers

Forced draft cooling towers are the oldest types of mechanical draft towers. The fan being located at the base of the tower so that they force air into the sides of the tower and flows upwards through the falling water and out at the top of the tower. The air distribution is poor since the air must make a 90 0 turn while at high velocity. In forced draft tower the air is discharged at low velocity from a large opening at the top of the tower. Under this condition the air posses a small velocity head and tends to settle into the path of fan intake. This means that fresh air is contaminated by partially saturated air which has already passed through the tower. This condition is known as recirculation and reduces the performances of cooling tower.

Induced draft cooling tower

This tower efficiently and thoroughly eliminates the difficulties experienced from the forced draft type. The fan being located at the top of the tower, draws air through the louvers on all sides near the base of the tower, flows upwards through the falling water and discharges to atmosphere. In Induced draft tower, air is discharged through the fan at a high velocity and thus prevents air from

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settling at the air intake and thus eliminates recirculation. The higher velocity of discharge of the induced draft tower causes entrainment loss or drift loss of water.

In these induced draft towers, air flow may be either cross flow or counter current. At IFFCO-Kalol unit cooling towers are induced draft, cross flow type.

Demineralization Plant (DM Plant):-

Demineralization is the process of removing the mineral salts from water by ion exchange. Only those substances which ionize in water can be removed by this process. Demineralization use exchange of ion as a method of purification. Ion exchange is actually a chemical reaction in which mobile hydrated ions of a solid are exchanged for ions of like charge in solution. Demineralization process involves two ion exchange reactions. The cations (positive-ions) such as calcium, magnesium and sodium are removed in cation exchanger, and anions (negative-ions) such as chlorides, sulphates, nitrates etc. are removed in anion exchanger.

Quality of water comparable to that of distilled water is required for high pressure boiler operation. The presence of silica in such water is most undesirable, since the silica may permit the formation of boiler tube deposits or vaporize with the steam and cause turbine blade deposits. It is therefore necessary for demineralized water to have a very low silica content in order to be useful for boiler feed water purpose.

For cooling tower make up water, silica is not a critical parameter and therefore the water outlet of weak base anion exchangers is used as CT make up.

Cation exchange reactions

Reaction in cation exchanger can be represented by the following equations.

Re H + NaCl Re Na + HCl

2Re H + CaSO4 Re2 Ca + H2SO4

2Re H + Ca CO3 Re2 Ca + H2 CO3

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Anion exchange reactions

The following equation can be used to illustrate the manner in which anion exchange resins operate.

ReOH + HCl ReCl + H2O

2 ReOH + H2 SO4 Re2SO4 + 2 H2O

Degassing

For removing the carbonic acid formed by the removal of cations of carbonates a degasser is provided which will remove H2CO3 by the process of stripping with air. The reaction is as follows. No additional chemical is used in this process.

H2 CO3 H2O + CO2

Silica removal by strong base anion exchanger

The strongly basic anion exchangers will remove silica, sulphides and carbonates as well as the other common anions. For this reason, direct silica removal is possible. The removal of silica by strongly basic anion exchanger resin can be represented as follows:-

ReOH + H2SiO3 ReHSiO3 + H2O.

(Basic Exc. Resin) (Silicic acid) (Resin silicate) (water).

OFFSITESOffsite facility mainly consists of:-

1. Ammonia Storage Tanks 2. Narmada Water Treatment Plant 3. Effluent Treatment Plant

AMMONIA STORAGE AND HANDLING :-

(a) 10000 T ammonia storage tank

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10000 t atmospheric liquid ammonia storage tank was built by M/s Vijay tanks and vessels pvt. limited. It is a single wall cylindrical vessel with a fixed self supporting cone roof and insulated with polyurethane foam (PUF). Its diameter is 30 m and height is 21.5 m. The tank is provided with refrigeration system and sufficient safety gadgets.

(b) 5000 T ammonia storage tank

5000 t atmospheric liquid ammonia storage tank constructed by India Tube Mills ltd was installed in the year 1992. It is cup in cup double wall type, cylindrical vessel with suspended deck on inner wall and fixed self supporting cone roof on outer wall. The outer wall is insulated with polyurethane foam (PUF). The space between two walls remains filled with ammonia vapor which works as an insulator. The outer shell diameter is 23.29 m and height is 21.74 m while inner shell diameter is 21.79 m and height is 20.25 m.

(c) Rail tanker loading system

The surplus liquid ammonia from storage tanks is dispatched to IFFCO Kandla unit through rail tankers. For loading ammonia into rail tankers, five loading points are provided. At a time batch of five tanker wagons, each having capacity of 32 t\ can be loaded. Two no. of ammonia loading pumps each having discharge capacity of 105 t/ h at a pressure of 19.58 kg/cm2g are installed. These pumps are also utilized for supplying liquid ammonia to urea plant as and when required.

(d) Road tanker loading system

Surplus ammonia is sold to buyers through road tankers. To load ammonia in road tankers two loading stations are provided. Two ammonia circulating pumps each having discharge capacity of 10 t /h at 7.3 kg/cm2a are used for road tanker loading. A flow totaliser with auto shut off valve as per preset value is provided to facilitate loading of required quantity of liquid ammonia in road tanker.

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(e) Refrigeration system

The ammonia storage tanks are fully insulated and designed for maximum boil off of 0.04 % per day. Vapour pressure of ammonia is high even at atmospheric condition. To maintain nearly atmospheric pressure in the tank, the vapour generated has to be condensed. This is done by taking the generated vapours from storage tank to the refrigeration system where the vapours are compressed, liquified and returned to the tank in liquid form

(e) Flare stacks

Normally ammonia vapour generated from ammonia storage tank, vapour released from ammonia rail and road tankers during filling is taken to refrigeration system. When refrigeration system is under maintenance or sufficient refrigeration compressors are not available to take care of vapours generated or for time being vapours generation is high, ammonia vapour is released to flare stack and burnt.

NARMADA TREATMENT PLANT:-

The Narmada water is supplied from Jaspur village to Narmada water (raw water reservoir) at IFFCO-Kalol through pumps. The raw water is stored in raw water reservoir and is further pumped up in stealing chamber where it is mixed with Chlorine and PAC (Poly Aluminum Chloride) to remove smell, turbidity and any contaminants and is further passed through flash mixer and poured in Clariflocculator. The sediments collected in Clariflocculator are stored in waste pit the water from the Clariflocculator is now passed in another three way chamber where sand, gravels are present. Sand, gravels, concrete acts as a filter and filters the water into clear water. This clear water which free from sediments and contaminants is stored in clear water sump and transported to various places. During choking of sand and water backwashing is done with clear water for efficient working of sand. The waste is collected in waste and sludge pit and the sludge is used in fields or disposed off. Out of six pumps three pumps are operational and others are as standby for supply of clear water. The clear water is transported to following places:-

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w Cooling Towerw DM water plantw Domestic purposes at IFFCO Township Kasturinagar.

Thus Narmada water is treated and used in IFFCO-Kalol facility.

EFFLUENT TREATMENT PLANT(ETP):-

(a) Effluent treatment & disposal

The effluent waste generated from the plants before discharging outside the IFFCO Kalol premises shall confirm statutory regulations imposed by the State and Central Government Pollution Control Boards. Under effluents control & disposal system, the total liquid effluent generated from the different plants is segregated in two categories viz. strong effluent and bulk effluent.

This effluent is collected either into strong effluent storage tanks or bulk effluent tanks. Open channels water is collected in bulk effluent tanks. Weak effluent segregated from the water treatment plant is collected in weak effluent tank-B and same is allowed to mix in bulk tank-A for better mixing and neutralization.

Water from urea plant drains and washings is collected in separate tanks known as balancing ponds and diverted either to bulk or strong effluent as per its analysis.

(b) Bulk effluent treatment and disposal

Effluent water containing comparatively very low concentration of pollutants is called bulk effluent. The effluent from following sources is collected in bulk effluent storage tank.

Water treatment plant with low concentration of salts Inert gas generation plant SPC / polisher unit regeneration Cooling water blow down

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From hydrolyser system during upset condition. Sand filters backwash Oil separator Domestic effluent. HCl fumes scrubber’s water

The pH of the bulk effluent is continuously recorded by pH analyzer. pH is controlled by dosing H2SO4 or 2 % spent NaOH collected from regeneration of SBA units in water treatment plant. Samples are also analyzed in laboratory at different intervals. Bulk effluent is discharged outside IFFCO premises once the analysis report confirms to the permissible limit set by Gujarat Pollution Control Board (GPCB).

(c) Strong effluent treatment and disposal

The concentrated effluent from water treatment plant is collected in strong effluent tank and discharged to solar evaporation lagoons inside the IFFCO premises with the help of strong effluent pumps.

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CONCLUSION

I am very grateful to IFFCO-KALOL, for giving me the opportunity to get a practical overview of the fully functional chemical plant. The experience of gaining practical knowledge was really great and will surely be of great help in my future. The environment of IFFCO-KALOL is very decent and highly motivating, as all the employees and officials helped me in every possible manner to gaining the knowledge about plant and processes carried out with great enthusiasm. I have gained a lot of experience, apart from academics and technical point of view. Once again, I am heartily thankful to all the employees, officials and fellow trainees, who contributed in making my internship at IFFCO KALOL, more interesting, more fruitful in any possible way.

Thank You.

Daxit Akbari

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REFERENCES

Website- www.iffco.coop Ammonia plant Iffco-Kalol manual Google Images IFFCO-Kalol Urea plant Iffco-Kalol manual Fire and Safety Iffco-Kalol Manual Utility Iffco-Kalol Manual Offsite Iffco-Kalol ManualPlant Operators and Technicians

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