AN INDUSTRIAL TRAINING REPORT
AT
KALOL UNIT Submitted by SIDDHANT DHIMAN Pursuing B.Tech. in Chemical Engineering PANDIT DEENDAYAL PETROLEUM UNIVERSITY
Raisan, Gandhinagar Gandhinagar - 382007
Training Period
05/06/2017 to 20/06/2017
1
ACKNOWLEDGEMENT
It gives me pleasure in submitting this in-plant training report at the end of training period period from 05/06/2017 to 20/06/2017 at IFFCO IFFCO Kalol unit.
I would like to express my heartily gratitude to all those who gave me that valuable opportunity to understand and complete my industrial training at IFFCO, Kalol. I would like to thank Indian Farmers Fertilizer Cooperative Limited, KALOL for providing me this training t raining and for guiding gu iding throughout the training and also allowing me to work in this premier organization and helped to make me stand in this competitive area. I would like to present my heartiest thanks to the JGM (Technical), Shri O.P. Dayama Sir and
Sr. Manager (Training) Shri M. Srinivas at IFFCO Kalol.
I also thank Dr. Pravin Kodgire Sir (H.O.D. of our department) and Training & Placement Cell of Pandit Deendayal Petroleum University for permitting me to pursue summer internship at IFFCO, Kalol. With the support o f Operators of different different plants p lants and most helpful library of IFFCO, I was able to complete the Training Report in due time.
Thank you, SIDDHANT DHIMAN
2
ACKNOWLEDGEMENT
It gives me pleasure in submitting this in-plant training report at the end of training period period from 05/06/2017 to 20/06/2017 at IFFCO IFFCO Kalol unit.
I would like to express my heartily gratitude to all those who gave me that valuable opportunity to understand and complete my industrial training at IFFCO, Kalol. I would like to thank Indian Farmers Fertilizer Cooperative Limited, KALOL for providing me this training t raining and for guiding gu iding throughout the training and also allowing me to work in this premier organization and helped to make me stand in this competitive area. I would like to present my heartiest thanks to the JGM (Technical), Shri O.P. Dayama Sir and
Sr. Manager (Training) Shri M. Srinivas at IFFCO Kalol.
I also thank Dr. Pravin Kodgire Sir (H.O.D. of our department) and Training & Placement Cell of Pandit Deendayal Petroleum University for permitting me to pursue summer internship at IFFCO, Kalol. With the support o f Operators of different different plants p lants and most helpful library of IFFCO, I was able to complete the Training Report in due time.
Thank you, SIDDHANT DHIMAN
2
PREFACE It is true that studies cannot be perfect without practical training and perfection is the basic necessity necessity of o f technical students. He must be technically sound as well as enrich with practical knowledge.
In practical training a person deals with many technical problems. Aim of in-plant training is to learn process and technology as real and also to learn industrial management and discipline.
We got a chance to improve life skills like communica co mmunication tion skills, self esteem, team work, creative thinking thinking etc. which are very important for making career.
Thus it is important for every person to be exposed to training in some kind of an industry or others to enhance enhance their knowledge.
SIDDHANT DHIMAN
3
TABLE OF CONTENTS
Chapter no.
1
Title
Page no.
Introduction
8
1.1
About IFFCO
1.2
Production Performance
1.3
Overview Of Iffco- Kalol Units
1.4
Various Plants
2
About training plant 2.1
Ammonia Plant
2.2
Raw Materials
11
Products 2.3
3
Process Details
15
3.1
Various Process For Ammonia Production
3.2
At IFFCO Kalol
3.3
Catalyst Used in Process
3.4
Process Description
3.5
Chemical Reaction
3.6
Urea Plant
4
Equipments And Instrumentation 4.1
Equipments Detail
4
35
4.2
Primary Reformer
4.3
Secondary Reformer
4.4
Primary Waste Heat Boiler
4.5
Secondary Waste Heat Boiler
4.6
Shift Convertor
4.6
HT Shift Conversion
4.7
LT Shift Conversion
4.8
CO2 Absorber
5
Process utilities 5.1
6
43
Utility Plant
Health, hazards & safety
54
6.1
Introduction Of Industrial Safety
6.2
Safety
6.3
Accedent
6.4
Accedent Factors
6.5
List Of Safety Equipments
6.6
Safety Precaution
6.7
Fire Hazards
6.8
Principles Of Fire Extingushing
6.9
Color Coad For Pipeline
6.10
Fire Protection
5
7
Bagging And Material Handling 7.1
59
There Are Different Types Of Conveyors, Machines, Heavy Equipments in This Plant
7.2
Detailed Description
7.3
Effluent Treatment And Disposal
7.4
Type Of Liquid Effluent
8
Environment & Pollution 8.1
Control Air Pollution
8.2
Solid Waste
8.3
Water and Noise Pollution
66
6
CHAPTER 1 :-INTRODUCTION
Fig. 1.1 View of IFFCO
1.1 About IFFCO
The total investment for the plant is around Rs.1150 crores. IFFCO has modern fertilizer plants,
At Kalol in Gujarat
At Kandla In Gujarat
At Phulpur in Utter Pradesh
At Aonla in Utter Pradesh
They have total annual production capacity of 56.63 lakh tons of fertilizer.
1.2 Production Performance
The production records for all four four units are excellent. Since inception, inception, the capacity capacity utilization achieved is always higher than the national average. IFFCO IFFCO has won several awards for the Fertilizer Association of India (FAI), National productivity Council 7
and national and international safety councils for outstanding production performance and in safety measures.
1.3 Overview Of IFFCO - Kalol K alol Units
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, 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 pro cess of M/s. M.W. Kellong, USA US A and 1200 tpd urea plant was based on co 2 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.
1.4 Various Plants
1.4.1 Ammonia plant The plant is being designated to produce 1100 tonnes to nnes of ammonia 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 tonnes ammonia per day is used used in the urea plant and remaining remaining is stored in atmospheric atmospheric storage tank.
1.4.2 Urea plant The 1650 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.
Utility plant: 1.4.3 Utility
Water Treatment Plant
Cooling Towers
Air Compressor and Inert Gas Generation Generation
`Steam Generation 8
1.4.5 Offsite Plant
Storage(naphtha,LSHS,NH3) Narmada Water Water Treatment Plant Plant Effluent Treatment Plant
9
CHAPTER 2 :- ABOUT TRAINING PLANT 2.1 Ammonia Plant
2.1.1 Introduction: The plant was commissioned in November, 1974. It was the first large capacity single stream plant in India. Name of Process
: Steam Hydrocarbon Reforming Process
Designed By
: M.W. Kellogg
Capacity
: 1100 Tons/Day
Feedstock
: RLNG
Fuel
: Natural Gas
2.2 Raw Materials
2.2.1 Raw Materials: Raw materials involved are:
RLNG: Source: GSPL---Gujarat State Petronet Ltd. State: gaseous Pressure: 37 kg Temperature: 20 deg C
Utility: Fuel: associated gas Naphtha: 71915 kg/hr
NAPHTHA Source: IOCL State: liquid Mol.wt.: 92.24 Quantity: 14733 kg/hr Composition: 100%(mol%) Sulfur: 100 ppm
10
CHEMICAL a-MEDA solution: 40%
POWER 43Kwh/T
ENERGY 43Gcal/T
2.3 Products
Products produced are:
Ammonia
Carbon Dioxide
2.3.1 Ammonia
2.3.1.1 Physical and Chemical properties: At Atmospheric temperature & Pressure Ammonia is a sharp colorless gas.
Formula
:
NH3
Specific Gravity
:
0.682
M.W.
:
17.03gm/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
2.3.1.2 Chemical Structure:
Fig. 2.1: Ammonia Structure
11
Anhydrous NH2 is present both in the gaseous and liquid under atm pressure and temperature condition it is present in gaseous foam.
Ammonia readily dissolves in water forming aq. NH3 with liberation of heat.
Ammonia vapor is colorless & has pungent o dor NH3 with its own warning agent.
Ammonia is lighter than air & therefore, in open atm it will by dispersed by virtue of its own burgundy. However, air NH3 vapor form liquid may form NH3 air mixture heavier than air, which may stay close to the ground for sometimes.
2.3.1.3 Hazardous Properties
When Ammonia stored in closed container NH 3 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 NH 3 should be avoided since under certain condition explosive chemical compounds resulting.
NH3 is an irritating gas & will affect muscles, membrane & eye.
2.3.1.4 Hazards Identification:
Color
:
colorless
Physical form
:
gas, liquid
Odor
:
pungent odor
Physical hazards
:
Containers may rupture
2.3.1.5 Uses of Ammonia:
Ammonia is used directly as fertilizer.
Formulating different nitrogenous & phosphoric fert ilizer
For liquid and solid nitrogenous fertilizer like urea, ammonia sulphate, DAP, NaNO 3, NHNO3, etc.
For chemical compound like crylonitrile, Caprolactum, nylon-6.
A refrigerant for large-scale air conditioning & refrigeration. 12
Formulating granular mixed fertilizer.
Ammonia blue print machine.
2.3.2 Carbon Dioxide 2.3.2.1 Properties of Carbon Dioxide:
At atmospheric temperature and pressure CO2 is colorless gas.
Formula
:CO2
M.W
: 44
Nature
: Acidic in water
Odor
: Odorless
Color
: Colorless
2.3.2.2 Uses of Carbon Dioxide:
Refrigerant in ice-cream industries, dairies, food product industries, bear industries, in cold industries etc.
Fire extinguisher
Mfg of salicylic acid, urea, various carbamates etc.
13
CHAPTER 3 :- PROCESS DETAILS 3.1 Various Processes For Ammonia Production
For ammonia production synthesis gas is produced by following pro cess.
Low temperature Non catalytic partial oxidation
Catalytic partial oxidation
Steam hydro carbon reforming process
And ammonia from synthesis gas is produced by following methods:
The Claude Process
The Forster Wheeler-Casale process
The M.W. Kellogg process
Foster Montecatini process
3.2 At IFFCO Kalol
“Steam Hydrocarbon Reforming Process” is selected for process synthesis and “The M.W. Kellogg Process” is selected for ammonia production.
Reasons for Selection Of Steam Reforming Process
From the steam reforming process generate more hydrogen the partial oxidation process.
Steam reforming process requires less feed than partial oxidation process.
Production of ammonia from coal plants is more costly than fro, conventional gas based processes, because of the extensive solids handling and effluent treatment facilities required.
From steam reforming process generation of pollution is less than other processes.
3.2.1 Advantages of This Process
Intensive heat recovery
Generation of steam which can be imported.
Less dependency on electricity 14
Capital cost is least
3.3 Catalyst Used In Process
Equipments
Catalysts
Desulfurizer
:
Primary Reformer
:
Nickel
Secondary Reformer
:
(i) Chromium (top)
Activated Carbon
(ii) Nickel (bottom)
Shift Converter H. T. Section
:
Iron Oxide
L. T. Section
:
Copper and Zinc Oxide
Synthesis Converter
:
Iron Oxide
Methanator
:
Nickel
Pre-reformer
:
Nickel
3.4 Process Description
Fig. 3.1: Flow Diagram of Ammonia and Urea
15
3.4.1 Steam reforming process The manufacturing of AMMONIA involves following operations/processes.
Raw synthesis gas preparation. RLNG Primary reformer Secondary reformer Co-shift conversion
Synthesis gas purification.
Compression of synthesis gas and ammonia synthesis.
Refrigeration system.
Purge gas recovery system.
Raw Synthesis Gas Preparation
Raw synthesis gas is produced from R-LNG.
Desulphurizing the R-LNG Feed
L.N.G. is supplied at a pressure of 40kg/cm2. It contains sulfur compounds which are removed by passing the gas through Desulfurizer containing activated carbon. The gas exit the desulphuriser is expected to contain less than 0.25 RPM of Sulphur. The sulphur free feed gas is mixed with process steam and the combined stream enters and feed preheat coil in the convection section of Primary Reformer furnace.
Primary Reformer
Desulphurised gas is mixed with steam and heated to 430 - 465 oC in HT convection zone of balanced draft reformer furnace. The gas is then passed through 336 Nos. tubes filled with nickel catalyst and heated up to790 - 815 oC by external firing from the top. Total 126 Nos. burners are provided at the top for heating the gas. The flue gas at about 1000oC is collected in tunnels and taken to HT convection zone where heat is recovered in heating the mixed feed and air used in secondary reformer. The flue gas is then mixed with the flue gas from auxiliary boiler and goes to low temperature zone where heat is further recovered in super heating the HP steam, heating fuel gas and combustion air. The 16
cooled flue gas is discharged through the stack at 140 - 180 oC. From primary reformer a mixture of hydrogen, carbon monoxide, carbon dioxide and methane is obtained.
Secondary Reformer
The process gas at 824Deg.C from primary reformer enters the secondary reformer via water jacketed transfer line and a chamber near the top of secondary reformer and is directed down ward through a diffuser ring to enter the combustion zone. Preheated air is introduced through a nozzle located just below the diffuser ring. The oxygen of the air burns with hydrogen of process gas and raises the gas temperature. At higher temperature balance methane reacts- with steam and its content is reduced from 10.3% to 0.32% approx. The gas enters the chromium and nickel catalyst for reforming. The gases leave the secondary reformer at 1000Deg.C and split to pass through the shell sides of two "bayonet type" primary waste heat boiler. From these waste heat boilers the gas at 452Deg.C enters secondary waste heat boiler. The flow through the tube sides of the waste heat boiler is boiler water. The process gas from waste heat boiler at 371Deg.C goes to H.T. shift convertor.
CO Shift Conversion
The cooled gas at 330-340OC passes through HT shift converter containing copper promoted iron catalyst. Part of CO is converted to CO2 and heat of exothermic reaction is utilized for HP steam generation and process gas / BFW heating. The cooled gas then passes through LT Guard and LT shift reactors, both containing copper- zinc catalyst. LT Guard is meant for protecting the LT shift catalyst from poisoning and thereby increasing its life. CO conversion reaction almost reaches equilibrium in this reactor. The heat of hot gas leaving the LT shift reactor is utilized for BFW heating. The exit gas from the LT shift converter contains mainly Hydrogen, CO 2 and Nitrogen with small quantity of CO.
Synthesis Gas Purification
Carbon Dioxide Removal and Recovery 17
Removal of CO2 from raw synthesis gas is carried out in two stages of absorption by counter current contacting of the gas with 30 to 40% by wt. MDEA solution in packed bed tower. The gas pass through a distributor in the bottom of CO2 absorber. The up flowing gas passes through four beds of packing and comes out from the top of absorber. The top two beds contain 38mm. stainless steel slotted (Hypack) rings. The bottom two layers consists of 50mm. S.S. slotted rings (hypack). As the gas flows up the packing it contacts down flowing semi lean and lean 30 to 40% by wt. MDEA solution which absorbs the CO2. The process gas leaving the absorber contains 0.1% CO2. Absorber operating at 26-29 kg/cm2 pressure and then stripping of CO2 rich solution at 1.6-1.4 kg/cm2 pressure. CO2 free raw gas is fed to methanator and recovered CO 2 is sent to Urea plant after cooling. Methanation Of Unconverted CO And Unabsorbed CO2
Unconverted CO (about 0.15- 0.3%) and unabsorbed CO2 (400-1100 ppm) in the raw gas are converted to methane at 275- 300 OC in the methanator. The process gas enters at the top of methanator after being heated up to 316 C . Methanator contains a bed of nickel catalyst where traces of CO and CO 2 in process gas react with hydrogen to form methane and water. The temp. of effluent gas leaving the methanator at bottom is raised to 347 C due to exothermic nature of reactions. The total amount of (CO+CO 2) leaving the methanator will be about 1 ppm. The cooled gas now called synthesis gas is then compressed. The purified gas exits the methanator at 310- 318O C.
Compression of Synthesis Gas And Ammonia Synthesis
The purified, cooled synthesis gas is compressed in a four stage centrifugal compressor. At the fourth suction gas is mixed with recycled gas from the ammonia synthesis section. The compressed gas is heated up to 130 OC and the same is sent to ammonia converter. The converter has three beds of iron catalyst. The synthesis gas enters top bed at 350 OC after being heated in the convector. Before entering to the second and third beds, the gas is quenched to control the rise in temperature due to exothermic ammonia conversion reaction.
18
The exit gas contains about 16% ammonia, which is recovered by cooling the gas in chillers. After recovery of ammonia, synthesis gas containing about 2.5% ammonia is recycled. The separated liquid ammonia is warmed and sent to Urea plant at 15-30 OC or it is chilled and sent to storage at – 30 to -33 OC .
Refrigeration System
Four-stage centrifugal refrigeration compressor is provided for refrigeration in the ammonia synthesis section. The primary purpose of this is to condense product ammonia for separating it from the converter feed. Further it is used to cooled make up gas for separation of water, to condense and recover liquid ammonia from purge gas, to cool the product to – 33 OC and degassing inert. Letting down its pressure in steps purifies the separated ammonia. A refrigerant compressor is provided to compress the vapor ammonia used in chillers to cool high pressure synthesis gas process. The product ammonia is sent to plant at 40o C and/or storage tank at -33o C.
Purge Gas Recovery System
As the ammonia conversion is very less, large quantity of unconverted gas is recycled. In order to avoid buildup of inert in the loop about 10,000 NM3/hr of gas is purged. The purged gas contains hydrogen, nitrogen, methane and argon. In order to recover hydrogen and ammonia purge gas recovery plant has been installed The ammonia is recovered by absorbing and then stripping whereas hydrogen is recovered by cryogenic cooling. Purge gas after recovery of ammonia and hydrogen is used as fuel.
3.5 CHEMICAL REACTIONS
3.5.1 Primary Reforming CH4
+ H2O
CO+ H2
C2H6
+
3H2O
3CO
+ 5H2
C3H8
+
3H2O
3CO
+
;
7H2 19
n- C4H10
+ 4H2O
4CO +
9H2
3.5.2 Secondary Reforming 2H2
+
O2 + 3.715N2
→ 2 H2O + 3.715N2
2CH4 + 3.5O2 + 13.003N2 → CO2 + 4 H2O + CO + 13.003N2 3.5.3 Shift Conversion + CO2
CO+ H2O→H2
3.5.4 Absorption CO2
+ H2O→H2 CO3
3.5.5 Stripping H2CO3
→
H2O+
CO2
3.5.6 Methanation CO + 3H2
→CH 4
CO2
→
+ 4H2
+ H2O CH4+ 2H2O
3.5.7 Ammonia Synthisis N2
+ 3H2
2NH3
3.6 Urea Plant
The plant was commissioned in January 1975. It was the first large unit manufacturing plant in India & plant was further upgraded in 1997. Now a day the plant capacity is 1650 tons/day.
Name of the process
: Stamicarbon Stripping Process
Capacity
: 1650 tones/day
Feed stock
: Ammonia & CO2
3.6.1 The urea process consists of the following steps:
CO2 supply and compression NH3 supply and pumping
Reaction/High pressure synthesis
Recirculation system 20
Evaporation and prilling system
Prills cooling system
Urea hydrolyser and desorber
Steam and condensate
Formation of ammonia carbamate, at 25 0 C:2NH3 (g) + CO2 (g)
NH4COONH2 (g)
-38,086 cal/ g mole
Dehydration of ammonia carbamate to urea, at 25 0C: NH4COONH2 (S)
NH2CONH2 (l) + H2O (l)
+10,330 cal/g mole
Overall reaction at 25 0C:2NH3 (g) +CO2 (g)
NH2CONH2 (l) + H2 O (l)
-27,756 cal/g mol
CO2 Supply and Compression
The CO2 gas is available from ammonia plant at normal pressure of 0.14 to 0.22 kg/cn2 g and at
a temperature
CO2 spray water.
CO2
of 50* to 60* C. This gas is cooled and saturated in
and water flows counter currently through packed
polypropylene pall rings for cooling. A demister pad above the distribution provided the carryover along with exit CO2
tray is
from spray cooler.
Water from the bottom of the spray cooler is sent to the cooling tower spray cooler sump pump. The
bed of
by CO2
exit saturated CO 2 with water vapour enters CO2
knock out drum where the moisture is knocked out and drained.
Anticorrosion air is injected to
maintain the oxygen level of 0.60% in the CO2
stream for HP equipments activation to prevent corrosion. The CO 2 leaving knock out drum is compressed in Hitachi make CO2 centrifugal compressor. Hitachi CO2 compressor consists of two casings LP and HP casings each having two stages of compression. LP case is directly coupled with turbine running at 7160 21
rpm and HP casing runs at 14153 rpm through a step up gearbox. The CO2 is compressed from 0.16kg/cm2g to 157 Kg/cm2g. Drive turbine extraction cum admission condensing type is installed to run compressor with minimum governor speed of 6375 rpm and maximum speed of 7875 driven by 60 ata steam and 4 ata steam as induction steam.60 ata steam is supplied by generation plant at about 61.5 ata and 410*C. The steam after passing through exhaust end section of the turbine is condensed at a pressure of 0.94 Kg/cm2g at turbine outlet in the surface condenser. Noncondensable from the condenser are removed by steam ejector system operating by 4 ata steam. The steam exit of the ejectors is condensed in the heat exchangers with cooling water flowing in the tubes and is pumped to the dearator of the steam generation plant by the surface condensate pumps, The vacuum in the surface condensers is maintained by a set of two ejectors in two stages.
NH3 supply and pumping
Liquid ammonia directly from ammonia plant enters the urea plant battery limit at 20Kg/cm2 g and 40*C. The alternate source from ammonia supply is from atmospheric ammonia storage tank. The cold liquid ammonia is preheated at 40*C in the ammonia preheater 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/cm2. Out of total ammonia discharged by pumps , 90-95% ammonia goes to HP carbamate condenser and 5-10% goes to autoclave.
Reaction/High Pressure Systems HP stripper
22
CO2 gas with 0.60% oxygen and inert discharged from CO 2 compressor at 157 Kg/cm2 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 2.6mm diameter through which the liquid flows into the tubes. This exchanger acts like a falling film counter-current heat exchanger. The efficiency of exchanger depends on the formation of liquid film. Liquid d istribution 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 NH 3 and CO2 from the carbamate. From HP stripper top channel CO 2 along with liberated NH 3 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 153Kg/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.
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
HP ammonia pump at a pressure
of 153 Kg/cm2g
channel. HP stripper exit gas is rich
in CO2 and the NH3/ CO2 mole ratios around
1.7. The presence of 2.5% water and slightly higher
ammonia from
and 45*C enters the
top
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. 23
Carbamate solution joins the liquid ammonia stream and enters HP condenser. The mixed stream flows through the packed bed, located above the liquid distribution tray. Some of the vapors (NH3 & CO2 ) enter the packaging and a part of it condensed within the packaging .Uncondensed vapors 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 gas leaves HP condenser from separate nozzles at the bottom and enters the bottom channel of autoclave.
At the operating condition prevailing in 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 certain value otherwise the crystallization temperature
below a
of carbamate (153C) would
be reached. 90%(v/v) of the vapors condense in high pressure
condenser and the
remaining 10% are
necessary heat for
condensed in autoclave there by supplying
urea formation from carbamate.
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
Quantity of ammonia required to be introduced
at the
bottom of the autoclave.
into the autoclave is determined
from the process condition and plant load.
Autoclave receives liquid ammonia , carbamate solution and uncondensed NH3, CO 2 ,
O2 and inert from HP condenser and carbamate the four streams join at 4 different
solution from HP scrubber .All
nozzles at the bottom of autoclave and rises to
24
top through
11 sieve trays . Liquid
mixture of urea, carbamate , and water
overflows to the down corner 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, CO 2 will flow in
reverse direction to autoclave via
down comer & pressure rise will be very quick
& HP condenser temperature will
fall sharply.
The inert and unconverted NH3 and CO2 exit
the autoclave through an overhead
line to HP scrubber. Control Valve, 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 pressurization , relief values set at 161 ata
are installed on the autoclave
top exit gas line.
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
condensed while bubbling up through the head. A small amount of uncondensed and CO2
and the inert
leave the HP scrubber through inert vent valve to
get NH3
LP
absorber. CO2 is injected above packed bed for purging so as to prohibit any explosion that may occur due to presence of H 2 .
Heat of carbamate formation is removed by a closed condensate circulation system (CCS) .Carbamate solution formed overflows through a nozzle located above the „U‟ tube bundle to autoclave
LP Absorber And Scrubbing System:
Uncondensed NH3 , CO2 and incondensable 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 water is supplied by process
25
water pumps from lean ammonia water tank .A small amount o f uncondensed NH3 , CO2 and the inert leaves the LP absorber to ammonia scrubber. Final scrubbing of the vapors is achieved in ammonia scrubber with lean ammonia water or DM water before being vent to atmosphere.
Recirculation
Rectifying Column / Separator :-
The urea
carbamate solution from the HP
stripper is let down to
across stripper level control valve. As a result of
3.3 kg/cm2 g
pressure letdown, part
o
carbamate in the solution is vaporized to NH3 & CO2 & solution gets cooled up to 170 to 120 0C. the liquid vapour mixture flows into the top of rectifying column/separator. The liquid vapour mixture is sprayed over the packed bed of rushing rings through nozzle
& spray breaker in rectifying column.
The upper portion of rectifying column consist of
rushing rings bed & the lower
half of the column
separator. The urea
consist
of
a vapour liquid
carbamate
solution is collected over the cone & flows to the bottom channel of the recirculation heater. The recirculation heater is essentially a thermo syphoning heater. It is design to provide min. Residence time to urea solution At the elevated temperature level, so that biuret formation is limited. All the carbamate is decomposed & the urea solution Vapour mixture flows to the bottom of rectifying column/separator. Vapour is stripped off from liquid & rises upwards via packed bed where it meets descending urea carbamate solution thus rectification of carbamate solution takes place. Rising vapors are enriched. Heat of vaporization is supplied by the hot rising vapour. Vapour leaves the rectifying column & enters falling film type LP carbamate condensers.
Absorber, Condenser & Separator:
The overhead vapours leaving from rectifying column are introduced at the bottom of falling film type LP carbamate condensers. Part of the NH 3 & CO2 are condensed to form ammonium carbamate. Lean ammonium carbamate formed in 26
the flask tank condenser is introduced in to the gas inlet line of the LP carbamate condensers through a sparker 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.
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 controls the
recirculation system
atmospheric vent scrubber
atmosphere scrubber & effectively
by pressure by sending vapours to the
for further recovery
of NH3.
Pressure control in the recirculation system requires a the system is happens that
around
special operating
pressure of
2.5 to 2.8 kg/cm2 g & controlled by control valve. It so
system pressure is raised when the
condensation is
incomplete.
Uncondensed gases are taken to reflux condenser of hydrolyser system. Higher pressure in the recycle system is caused by incomplete condensation co2 & nh3.
Carbamate Solution Recycles:
Carbamate solution from LP carbamate separator is recycled to HP synthesis section via HP carbamate pumps. Around 35% of solution is pumped to HP scrubber &
the rest to HP carbamate
reciprocating pumps driven by variable speed
condenser.
Carbamate pumps are
motors via gearbox.
Flash Tank Condenser
Urea solution From rectifying column separator at 135 & 2.3kg/cm2 g pressure is flashed to flash tank separator, which is maintained at pressure of 1.06 kg/cm2 g. Urea solution from rectifying column is let down across the level control valve to flash tank separator. Liquid & gas phase are separated in flash tank separator. A considerable amount o f water & NH3 is liberated from the urea solution & this 27
liquid Vapour mixture enters the flash tank separator. Urea solution from the bottom of separator flows to
pre evaporator. Urea solution from the flash tank can be taken
directly to the urea
storage tank bypassing pre evaporator.
Vapours from the flash tank separator flows to the flash tank scrubber where residual urea, NH3 is scrubbed with ammonia water supplied by urea recovery circulation pups. The vapours leaving the scrubber are sent to the flash tank condenser where remaining NH3 & CO 2 are condensed by
cooling water to form
lean carbamate solution Heat of
of water formation is
reaction & latent heat
removed by circulating cooling water in the tube side of the condenser. Vapours leaving the flash tank condenser are sent to atmosphere 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.
Pre Evaporator:
The urea solution from the flash tank separator about 104 0C & about 1.06 kg/cm2 g vacuum pressure is flashed to pre evaporator which is maintained at 0.4 kg/cm2 g vacuum pressure. Urea solution Is heated up to 98.6 0C in two separate heat exchangers, which are parts of pre evaporator. Temperature of the exit urea solution is controlled by 4ata steam control valve provided on 4 atm steam inlet line. Exit urea solution at concentration of 82.6%. Temp 9.6 0C is drawn to urea solution. Storage tank. The vapour leaving he pre evaporator mainly consist of water & NH 3 are condensed in pre evaporator condenser with the help of cooing water passing through tube side the condensed Uncondensed
vapour from the
water is drawn to the rich ammonia water tank. condenser are connected to first evaporator off
28
gases there by vacuum in pre evaporator is maintained with the help of first evaporator ejector system.
Urea Solution Storage Tanks:
Two urea solution Storage tanks are installed to receive urea solution tank. Urea solution
from the pre evaporator is received
pumping to
material
onward
the evaporator. Urea storage tank is maintained under atm. Pressure urea
solution Tank also receives recycle solution of
& urea
in urea solution tank for
evaporation section during
startup
dust dissolved solution From prill cooling system & bagging & from handling plant via prill cooling system.
Evaporation And Prilling System:
Urea solution having a concentration of 82.6% is pumped from tank to the first evaporator separator by urea solution pump.
the urea solution The evaporator
separator operates under vacuum of 0.31 kg/cm2 g. Urea solution is heated in
the shell
& tube type heat exchanger with urea solution flowing in the
& 4 atm
tubes
0 steam on the shell side the urea solution is heated from 98.6 to 130 C to achieve
urea solution concentration of 95%.
The urea solution From the climbing film single pass e vaporator flashes into the separator mounted directly on the evaporator. The water vapour together with some ammonia is separated
0 Urea solution at a temp of about 13 C having concentration of 95.5 % then flows from first evaporator, it is further concentrated to over 98.5% urea melt for prilling
it is
heated on tube
side by 9 at a steam
on
shell side. Urea from the second
evaporator flashes directly to the separator. The overhead from it condensed & collected in ammonia water tanks.
Prills Cooling System:
29
Urea from the second evaporator enters in suction of urea melt pump. Urea melt is pumped to the prilling equipment on top of prilling tower.
urea in fine droplets. Air is drawn from the bottom of prilling tower, via fixed openings by 4 prill tower induced fans situated
at the prilling tower
top & flows
counter current to the flow of urea prills.
During the free fall in the tower the heat of crystallization is being carried away by air entering at the bottom of tower. The droplets of urea first
solidify
then
0 cooled to a temp 80 to 90 C. The hot urea prills fall on the scraper at bottom & there fed to prill tower conveyer.
Material handling :
Urea prills after discharging from product conveyer flows into the fluidized bed cooler through inlet nozzle. atm air is supplied by inlet air fan for cooling. During fluidization on perforated plate of fluidized prills is taken away by air & cooled urea prills
bed cooler heat of hot urea flows over discharged nozzle.
Exhaust air along with some fines of prills to dust removal systems after removing dust clean air is
exhausted to atm. by chimney. Dust separated is collected in three
silos.
Urea Hydrolyser & Desorber :
Process water containing 6.2% NH 3, 4.3% CO2 & 1.3% urea by wt from strong ammonia water tank is pumped with desorber feed pump via desorber heat exchanger to the first desorber. The first desorber is having 20 nos. of sieve trays in order to provide uniform contact between liquid & vapour. In the first desorber bulk of NH 3 & CO2 is stripped off by means of overhead vapours from second desorber & hydrolyser.
Pre desorber feed water desorber is
pumped by
containing about 1% NH3 from the bottom of the first hydrolyser feed pump through the tube side hydrolyser 30
preheater, where its temp. is raised & fed to the top of the hydrolyser. In the hydrolyser urea in feed water is converted to NH 3 & CO2 according to hydrolysis reaction :
NH2CONH2 + H2O
2NH3 + CO2
The hydrolyser is operated at temp. Of 190 at top & 200 0C at bottom. Heat required for hydrolysis of urea & raising temp. to
200c is supplied by 23
ata superheated
steam fed into hydrolyser bottom through sparker. The flow of vapour in hydrolyser is counter current. In the short pipe down comer are fixed at
hydrolyser 20 nos. of sieve tray with a spacing of 1100mmm to provide
contact between. Liquid & vapors. The pressure of NH3 retards The ammonia produced as a result
& solution
of hydrolysis
uniform
hydrolysis reaction.
reaction is simultaneously
stripped by the uprising vapours. The urea concentration of less than 10 ppm in effluent can be achieved in counter current type of hydrolyser. 0 0 Effluent leaving hydrolyser bottom is cooled from 200 C to 146 C in the
hydrolyser preheater with the hydrolyser feed
for final striping vapour leaving at top of
water & is fed to second desorber hydrolyser are fed to first desorber
below 5th tray as supplementary stripping medium & for recovery of ammonia & CO 2.
The overhead vapors from the first desorber are taken to vertical reflux condenser where it is in
almost completely condense in shell side the cooling water is
supplied at tube side of reflux condenser. Ammonia water from the outlet of flash tank scrubber is pumped by pump & introduced in the of gas line. This will help condensation in the reflux condenser. Uncondensed gases are separated & fed to the atm vent scrubber for recovering NH3. Liquid from the reflux level tank is transferred by means of reflux pump to LP carbamate condenser. A small part of liquid is fed at top of first desorber as reflux
to control the water content I top
product by controlling top temperature of first desorber around 115 0C
31
In second desorber the remaining NH3 & CO2 means of saturated LP
the overhead vapours bearing NH3 &
steam available &
CO2 are fed to the first desorber bottom as
in the effluents stripped off by
stripping medium.
The effluent from second desorber bottom containing less than 10 ppm NH3 ,urea 0
is cooled from 137 to 47 C in the desorber heat exchangers by exchanging heat with first desorber bottom cooler. The final effluent can be diverted to effluent is sent to cooling tower directly or it is along with spray cooler
taken to CO2 spray
water with help of
cooler & then to cooling tower
spray cooler pumps.
And Steam Condensate System
Urea plant uses steam at five pressure levels 60ata, ata steam is
received in urea plant battery limit from
40ata, 23ata, 9ata & 4ata. 60 steam generation plant.
23 atm steam requirement is met by letting down 60 atm steam from turbines of CO 2 compressors. 9 atm steam is produced by letting down 23 atm steam. 4 atm steam is generated from the HP condenser & turbines of steam generation plant additional
from back pressure steam
requirement of 4 ata steam if any, is met
by letting down 9 atm steam.
60 atm steam is generated in BHEL boiler & supplied
to urea plant at 60 atm &
the steam is utilized in urea plant turbines plant needs
about 78
tones of 60 atm
steam to run Hitachi CO2 compressor turbine.
40 atm steams available from utilities at urea plant battery limits
for driving the
turbine of main lube oil pump for NP/PB CO2 compressor turbine. It is generated through letting down 60 ata steam through control valve. 23 atm steam is extracted from CO2 compressor turbine is used in HP stripper. 32
9 atm steam is generated by flashing 23 atm steam condensate from 23 atm steam saturator. A part of this flashed to form 9
ata steam which flows to
consuming
station. A small quantity of 23 atm steam is also spurged into 9 atm saturator to meet the additional demand for 9 atm steam. It is mainly used in second evaporator.
4 atm steam is produced by natural circulation of condensate to shell side of HP condenser. It is mainly used in first evaporator, recirculation heater, CO 2 centrifugal compressor turbines, second desorber & pre evaporator. 63 t/h of 4 atm steam is produced from HP condenser
33
CHAPTER 4 :- MAJOR EQUPMENTS AND INTRUMENTATION 4.1 Equipments Detail
4.1.1 Natural Gas Desulphuriser
Purpose:
To remove sulfur compounds, which are poisonous for the catalysts, from LNG with activated carbon by absorption.
Operating conditions:
LNG contains about 0.5 to 3ppm sulfur. Sulfur is absorbed by activated carbon. The outlet gas should contain 0.2ppm sulfur.
Description:
The feed gas contains about 0.5 to 3ppm sulfur compounds in the form of sulphides, disulphides, thiophenes etc, and these should be removed as they are poisonous for the process to follow. There are two desulpharisers out of which one is online while the other is a stand by which is used when the first one is regenerations.
The process employed here is adsorption. For desulphurization activated carbon catalyst is used. There are two beds of catalyst-at the top and bottom. It adsorbs the sulphur compound. RLNG enters the desulpharisers at the top and is removed from the bottom with a sulphar impurity of about 0.2ppm. The gas then enters the Knock-out drum in which the liquid hydrocarbons, if any are knocked out.
4.2 Primary Reformer
Purpose: To react liquefied natural gas with steam in presence of nickel catalyst to get H 2 for synthesis of NH3. Pressure: 31.3 kg Temperature:818 de 34
Fig. 4.1 Primary Reformer
Description:
Reforming is an initial process of forming Hydrogen and Nitrogen in ammonia plant after the process of desulphurization. The primary reforming is carried out in the primary reforming(furnace). The gas from the desulphuriser is first preheated in the feed preheated in the convection section. The inlet and outlet temperatures are 93°C and 232°C respectively. The above natural gas is mixed with super- heated steam to get a steam to carbon ratio of 3.5:1. The mixer at 295°C is then passed through the second feed pre heater coil in the convection section to achieve a temperature up to 525°C. The final mixer goes to the primary reformer.
The primary reformer is rectangular in shape. Outside is consisting of S.S body and there are insulator bricks inside. It consists of tubes packed with nickel which is used as catalyst. These tubes are vertically with the help of spring suspension and between the vertical rows of these tubes the burners are installed which use natural gas and associated gas as a fuel for heating the tubes. The spring suspensions are made provide for the 35
expansions and contractions of the tube material. There are in total 336 tubes and 126 burners.
Inside primary reformer endothermic reaction takes place at about 818°C. The product each raw of tubes is connected at the bottom. The product from each of 42 tubes meets at the centre and forms the single line called „Transfer line‟ which rises upward. The temperature of the gases inside the tube is 852°C. The „Transfer Line‟ directs the flow to
the secondary reformer.
4.3 Secondary Reformer:
Purpose:
To complete the reforming of methane, which comes out from primary reformer. Also nitrogen is introduced in the process by burning a part of reformed gas with oxygen contained in the air at the top section of secondary reformer. Pressure: 31.0 kg Temperature: 820 deg C
36
Fig. 4.2 Secondary Reformer
Description:
The partially reformed gas from primary reformer entered the secondary reformer at a temperature of 820°C. The flow is downward a centrally located air inlet pipe, air supplied by process. Air compressor is preheated with steam. A small quantity of steam is mixed at air inlet to the air pre heater coil to ensure continuous flow into the secondary reformer
The process is namely exothermic and the temperature in the combustion zone is about 995°C. In the secondary reformer the working pressure is about 31 kgf/cm 2. The purpose of the secondary reformer is to complete the reforming of methane which comes out from 37
the primary reformer. Also nitrogen is introduced in the process by mixing a part of reformed gas with oxygen contained in air the section of secondary reformer.
The hot gases pass through the bed of nickel catalyst and their temperature is around 992°C. The heat is recovered from the reformed gas by use of waste heat boiler and the steam produced is again used in the other operations.
4.4 Primary Waste Heat Boiler:
Purpose:
Steam generation from secondary reformer effluent gases. Pressure: 30.9 kg Temperature: 996.7 deg C
4.5 Secondary Waste Heat Boiler:
The reformed gas from primary reformers enters the top of the secondary reformer, which is mixed with air by “John Zive Air Mixer”.
Nitrogen is introduced in the process by burning of part of the performed in the air at HT top section.
The heat of combustion is made available for the endothermic reaction of the methane reforming at elevated temperature at bottom
section. Pressure: 105.4 kg Temperature: 313.90 deg C 4.6 Shift Convertor:
Purpose:
To convert CO of reformer gas to gain one mole of H2 per mole of CO for ammonia synthesis.
Design And Operating Details:
Table 4.1 High Pressure Section 31.8 kg/cm2
Operating pressure
38
Design pressure
34.1 kg/cm2
Vessel design temperature
482.2°c
Inlet gas temperature
355°c
Outlet gas temperature
422°c
Table 4.2 Low Pressure Section Operating pressure
29.1 kg/cm2
Design pressure
34.1 kg/cm2
Vessel design temperature
301.7°c
Inlet gas temperature
204°c
Outlet gas temperature
221°c
Max. allowable pressure drop through beds(total)
2.0
4.7 Ht Shift Conversion:
The reformed gas enters the HT section of the shift convertor at a temperature of 345°C and flows through the catalyst bed. The bypass is provided to control the HT shift converter feed inlet temperature. The catalyst used here is iron oxide.
By the reaction most of the carbon monoxide is converted to carbon dioxide also gives out heat. Above reaction is reversible and carbon monoxide is converted back into carbon dioxide which is favored at low temperature.
4.8 Lt Shift Conversion:
The gas coming out of the HT shift converter still contains about 2.5% carbon monoxide. The removal of this CO is done in this section. The temperature of the gas in the LT shit converter is about 200°C. The catalyst used here is copper. The heat is recovered from the gas before it is sent to the carbon dioxide removal section at low temperature.
The gas is first cooled by a desulphur heater with a spray of recycled process condensate pumped by pump from the raw gas separator. The quenching is done with the desulphur heater as the excessive high temp. can cause degradation of a-MDEA(aqueous-Methyl Diethanol Amine) 39
4.9 CO2 Absorber:
Purpose:
To remove the carbon dioxide contained in the raw synthesis gas by scrubbing it with 30% to 40% MDEA solution. Pressure: 27.4 kg Temperature: 75 deg C
Description:
In this section the bulk of CO 2 in the raw synthesis gas is removed by absorption using 40% MDEA solution at high pressure and low temperature. The absorption of CO 2 involves the reaction of dissolved CO2 in water.
With a-MDEA to form a loose chemical compound which can be easily dissolved at high temp. and low pressure. The raw synthesis gas at a pressure of 27.3 kg/cm2 .g and a temp. of 63°C contains about 18% dry volume of CO2 is introduced at the bottom of CO2 absorber.
4.10 CO2 Stripper:
Purpose:
To regenerate rich MDEA solution by steam stripper with the help of reboiler and there by realizing CO2. Pressure: 0.74 kg Temperature: 75 deg
Description:
In this section the bulk of CO 2 in the raw synthesis gas is removed by absorption, using at 40% aqueous methyl ethanol amine solution at relatively high pressure and low temperature. The CO2 is sent to urea plant , dry ice and balance if any is vented by atmosphere. The lean a-MDEA solution form the bottom of strippers is reused after cooling , for absorption of CO2 in absorber. 40
4.11 Methanator:
Purpose:
To convert small quantity of CO and CO2 to methane by reacting with hydrogen in presenc4e of highly active nickel catalyst. Pressure: 26.7 kg Temperature: 375.6 deg C
4.12 Synthesis Convertor:
Purpose:
In synthesis converter, H2 and N2 contained in the converter feed combine to form ammonia in presence of promoted iron catalyst at the prevailing temperature and pressure of 420°c and 135 kg/cm2 respectively. Pressure: 146.2 kg Temperature: top head=283.9 deg C Startup heater outlet=537.8 deg C Others part=146.1 deg C 4.13 Ammonia Separator:
Purpose:
To separate and remove maximum amount from recycle gas and slight traces of water, CO, CO2 contained in the makeup gas which are chilled to 28.9 C.
Table 4.3 Operating Condition
Temperature
-28.9c
Pressure
147.7 kg/cm
41
2
CHAPTER:5 PROCESS UTILITIES 5.1 Utility Plant:
5.1.1 Narmada Water System:
Generally fertilizer plants require a lot of water have raw water supply from river , lake , pond , sea
for the process. An industry may or subsoil resources, canal.
Narmada Water System In IFFCO (Kalol Unit):
IFFCO Kalol plant is away from the river and no lake is available in the nearby vicinity. Thus the water required is received from SSNNL (Sardar Sarovar Narmada Nigam Limited) Dholka branch canal near Jaspur village. Raw water is required in the plant mainly for.
Cooling tower (CT) make up water after partial treatment in WTP.
Blending to cooling tower make up water.
Boiler feed water make up tower after treatment in WTP.
Drinking water.
Fire water.
Service water & other miscellaneous uses.
Water to township.
This plant is designed for the treatment of 4 MGD = 1800M 3/Day water which is received from SSNNL (Sardar Sarovar Narmada Nigam Ltd.) Dholka branch canal near Jaspur village. The water from Narmada canal is stored in raw water reservoir capacity 4900 M3 is pumped to site in water treatment plant. This water is again stored in raw water reservoir capacity 20000 M3. From this reservoir we are treating the water in water treatment plant. Turbidity, suspended solids and microbiological growth is controlled by addition of Poly aluminum chloride and chlorine and then it pass to clarifoculator and sand filter. The clear water from sand stored in clear water sump capacity 10000 M3 is supplied to DM plant, cooling tower and for the domestic water us 42
5.1.2 Water Treatment Plant: Narmada water is supplied by Sardar Sarovar Narmada Nigam Limited from Jaspur village to pre-treatment plant and then to water treatment plant. The water treatment plant consists of cation, anion, storage base anion (SBA) and secondary mixed bed (SMB) units. The advantage of property of resin material to exchange in ion in its structure, for an ion in solution is utilized in the process of water treatment plant
The Water Treatment Process Consists Of Following Five Steps:
1. Exchange of Cations in Strong acid cation exchangers 2. Exchange of anions in weak base anion exchangers 3. Dissociation of carbonic acid in degasser unit. 4. Strong base anion (SBA) exchangers and 5. Degassing:
For removing the carbonic acid formed by the removal of cations of carbonates a degasser is provided which will remove H 2CO3 by the process of stripping with air.
The reaction is as follows. No additional chemical is used in this process. H2CO3
H2O + CO2
Strong Bed Anion Exchange:
Degassed water passes through a bed of strong base anion exchange resin. Strong basic anion exchangers will remove silica, sulphides and carbonates as well as the other common anions. For this reasons, direct silica removal is possible. The removal of silica by strong basic anion exchanger resin can be represented as follows.
ReHSiO3
ReOH + H2SiO3
+
H2O
At IFFCO (Kalol), water treatment plant (WTP) is broadly divided into two 43
categories: 1. Water treatment plant consisting of five units of strong acidic cation exchangers and weak base anion exchangers (DM Stream) for partially treated water as cooling tower makeup water. 2. Boiler feed water (BFW) treatment plant consisting of one co mmon degasser unit, four units each consisting of one strong basic anion bed exchangers (MB Steams).
Mixed Bed Exchange Unit:
In MB exchange unit water is passed through a bed of mixed resin i.e. cation resin and strong base anion resin. Here any residual cation and anion of the salts in water are removed. Chemical reaction for service and regeneration are sane as in case of cation and strong base anion (SBA) exchangers.
Cation Exchange Resin:
Some synthetic resins acts as cation exchange resins. These resinous substances reacts with water containing salts, replace the metallic cation of these salts by hydrogen ions n the resinous substance. Such resinous substance when exhausted can again be regenerated by acids having hydrogen ions.
If such a resinous substance is expressed as H 2Re, the chemical action can be written as follows: H2Re + CaSO4 H2Re + MgCl2
CaRe + H2SO4
MgRe + 2HCl
H2Re + Ca (HCO3)2 H2Re + 2NaNO3
CaRe
+ 2H2CO3
Na2Re + 2HNO3
In the equation, Ca, Ma and Na are retained in the cation exchange resins and respective mineral acids are provided, separating thereby Ca, Ma and Na from the water. At kalol, Unit steam of 4% HCI is passed through the bed of cation resin and following reactions will take place. Ca-Re+2HCI
H2Re + CaCl2 44
Mg-Re + 2HCI
H2Re + MgCl2
Anion Exchange Resin:
Some synthetic resins act as anion exchange resins. These resins remove negative ions such as chlorides, nitrates and sulphates from water by replacing OH ions. If we represent these resins as OH-Re, the chemical equation can be represented as follows.
OH-Re + HCI Cl
Re + H2O
SO4Re2+ 2H2O
2OH-Re+ NO3Re + H 2O
H2SO4
OH-Re + HNO3
When alkali is passed through the bed of anion unit, the following reaction take place. NH4OH + Cl-Re
NH4Cl
+
OH-Re
2NH4OH + SO4Re2
(NH4)2SO4
+
2OH-Re
NaOH + Cl-Re
NaCl
+
OH-Re
2NaOH + SO4Re2
Na2SO4
+
2OH-Re
The original resin from OH-Re is regained by regeneration of the anion unit with alkali and so the resin is ready for, further anion ion exchange.
Cooling Tower Make-Up Water Generation:
The Narmada water from pre-treatment plant is pumped to cation exchanger. The water first enters the cooling tower makeup-boiler feed water pretreated section consisting of five nos. of DM streams. In cation exchanger, where the water first enters, the salts presents in the raw are converted to their corresponding acid e.g. sulphuric acid, hydrochloric acid. The acidic water then passes through t he resin trap where the entrained resin is retained. Water then enters the exchanger where all the anions are removed by the weak basic anion exchanger resin. The water is again passed through a resin trap for removing any carry over of resin. The demineralized water, as it comes out of the trap after anion exchanger, contains 45
chlorides less than 0.5 ppm and suitable for consumption as cooling tower make up. This water is stored. in cooling tower make up water sump from where it is taken to the cooling tower through a cooling tower makeup water pump. The cooling tower make up water is degassed in a degassing cell of cooling towers.
The strong acid cation exchanger is filled with strongly acidic cation exchange resin, suitable for regeneration with 4% hydrochloric acid. The weak base anion exchanger is filled with weak base anion exchange resin, suitable for regeneration with 4% ammonium hydroxide or 4 % sodium
Hydroxide.
When water equivalent to the designed capacity if one stream has passed through one stream, as indicated by the flow integrator mounted on the panel, or the conductivity of the service water increases as indicated by the conductivity indicator mounted on the top panel, the unit will be shut down for regeneration purpose.
Up BFW Make Water Generation:
The water required for boiler feed purpose is
to be degassed before introduction into
the SBA units of the mixed bed section. The
outlet water from the weak base anion
unit goes to the top of an air blown degasser. The carbonic acid formed in the strong base cation exchanger is removed from the water in the degasser.
The degassed water from the degasser sump is pumped by degasser pumps to boiler feed water section consisting of four streams of strong basic anion & secondary mixed bed unit.
The strong acid cation resin is suitable for regeneration with 4 % hydrochloric acid and strong base anion exchange resin is suitable for regeneration with 4 % sodium hydroxide. The cation exchange resin exchanges hydrogen (H+) ions with positive charges contained in the water, while the anion exchange resin exchanges hydroxyl (OH') ions for the ions with negative charges. The net result for this process is the replacement of the dissolved salts with an equivalent quantity of water. The residual salts from cooling 46
water – boiler feed water section and silica in water is removed in the strong base anion bed and secondary mixed bed (SMB) unit.
When an equivalent quantity of water to the designed figure, as indicated by the flow integrator, has passed through the mixed beds, or the conductivity/silica exceeds the set limit, the stream will be manually shut down for regeneration.
5.1.3 Cooling Towers
Most industrial processes need cooling medium for efficient and proper operation. Water is the most effective cooling medium used today because,
It is normally plentiful
It is easy to handle and can carry large amount of heat per unit volume
It does not decompose
It is normally readily available and is in-expensive
The system using water as coolant is called as cooling water systems. During process, the cooling water gets heated up and must be either cooled before it can be used again or replaced with fresh water. In most industrial localities fresh water is too scarce to permit its unlimited use as a cooling medium.
The tendency of water tables for the bore wells is forcing the industries to conserve the water wherever possible and reusing the water to a maximum extent.-For reusing the cooling after, it must be cooled back to nearly ambient direct contact cooling tower where it is cooled with air In the cooling tower, ordinary the fresh cooling water requirement is by about 1.5 to 2.5 % of the circulation rate.
There are three basic cooling water systems.
1. Closed Recirculating System: 2. This system uses the same cooling water repeatedly in continuous cycle. First the water absorbs heat from process fluid, and then releases it in another heat exchanger. In this system, an evaporative cooling tower is not included. 3. Once Through Systems: 47
In these systems, the cooling water passes through heat exchanger equipment only once. The mineral content of the cooling water remains practically unchanged, as it passes through the systems
Open Recirculation System:
It consists of cooling tower, pumps and heat exchangers. The pumps keep the water circulating through heat exchangers where it picks up heat in the cooling tower heat is released from the water through evaporation. Thus the heated water gets cooled in the cooling tower with naturl or mechanical draft provided in the tower. Because of evaporation, the water in open recirculation system undergoes changes in its basic.
Spray pounds
Cooling tower
Evaporative condensers
This system permits great economy in makeup water requirement and average operating temperature range is 5 C to 17 C.
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 feeling 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 arranged in such a way that the water entering the distribution trays near the top of the tower. Fan mounted on top of the tower induces air into the tower through air inlet, placed on either side of the tower. Across this air flow, water drops fall through fillings.
When the water droplets existing in air evaporates, the quantity of heat about 540 kcal/kg is taken from the surrounding as latent heat of evaporation. In case that the temperature of hot water is higher than that of surrounding air, the heat removed from water and transferred to air is the sum of the sensible heat and latent heat of evaporation. The sensible heat is less as compared to latent heat. 48
Types Of Cooling Tower:
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 coo ling towers. 1. Atmospheric and natural draft cooling tower 2. Mechanical draft tower
Atmospheric cooling tower:
The atmospheric tower works on the atmospheric wind current. The air blows through the lower sides in one direction at a time, which shifts as per the season of the year and other atmospheric conditions. Since the atmospheric currents must penetrate the e ntire width of tower, the towers are made very narrow in compression with other type and must be very long to afford equal capacity.
Natural draft cooling towers:
These types of cooling towers operate in same way as a furnace chimney. Air is heated in the tower by hot water, so that its density is lower. The difference between the density of the air in the tower and outside the tower causes a natural flow of cold air into the tower must be tall for sufficient buoyancy and must have large section because of low rate at which the air circulates. Natural draft towers consume more pumping power.
The mechanical draft towers is subdivided into two types:
(i) Forced draft towers (ii) Included 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 the 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 deg turn while at high velocity. 49
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 possess a small velocity head and t ends 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 Towers:
This tower efficiently and thoroughly eliminates the difficulties experienced from the forced draft type. The fan being located at the top 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 settling 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 counter current. At IFFCO-Kalol unit cooling towers are induced draft, cross flow type.
5.1.4 STEAM GENERATION PLANT: The modem 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 pressure vessel into which liquid water is pumped at the operating pressure. After heat has vaporized the liquid, the resulting steam is then ready either for delivery to the use or for flirter heating in a super heater.
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, bid rum, forced draft furnace. It is o il and/or gas fired boiler of 80 t/h capacity at 61.5 Kg/cm 2g pressure and 410(+/-5) C temperature.
Principles Of Steam Generation And Circulation: 50
Within the steam generation, the steam formation of steam is hinged upon a successful transfer of heat. Once this transfer is made, steam formation will start. Steam formation can describe by use of a simple drum heated from beneath. Steam forms in bubbles to the surface where .the steam is released into the space above. Here in simplest form, three part cycles is common to every steam generator.
Flow water to the heated areas
Flow of steam and heated water to upper areas
Release of steam
There is a drum which has connected to it a loop of tubing, one of which is heated and the other unheated. Steam bubbles from in the heated leg, generally called a riser. The resulting steam water mixture is displaced by the re latively heavy water in the unheated leg or down comer and circulation flow of water is established. Under operating conditions, there is a continuous flow of water from the drum where steam releases. The factors influencing circulation are that the column of water in the down comer leg weight more than equal column of steam water mixture in the down comer leg. This difference represents the force available to overcome friction and maintain circulation.
As actual steam generator consist of many tubular circuits, with a drum or drums acting as a distributing and collecting device and releasing point for steam. However, actual steam, generators are not built up by merely multiplying the number of simple individual loops, the circuits are more complex and the number o f individual paths for steam water flow varies from po int to point. The three system of circulation adopted in boiler are
Natural circulation system
Controlled circulation system
Combined circulation system
Cooling tower make up water is
drawn after weak base anion exchangers and
the boiler feed makeup water is supplied after removal of silica and traces o cation
and anions mixed bed
insulator instead if
units. The deposit layer is non-conductive and
good. conductor which is very essential for maximizing
thermal efficiency of the
boiler and heat' exchangers. Modem high pressure 51
boilers need feed water, which should be of high degree of conditioned with certain chemicals.
The water
from Narmada contains turbidity but contains mineral
salts
e.g.
chlorides, sulphates, and carbonates of calcium, magnesium, sodium, iron salts & sand in suspension. The level
of chlorides in water is very less. The
hardness is classified into two viz. temporary hardness and permanent hardness.
The temporary hardness due to carbonates and bicarbonates of calcium and magnesium. Permanent hardness is caused by chlorides and sulphates of calcium magnesium. Bicarbonates of calcium and magnesium and sulphate of calcium from hard scales on boiler tubes resulting in
tube failure. Also, silica present
in the water has
higher pressure and temperature.
property of volatizing at
Chlorides and carbonates are responsible for corrosion in boiler system.
Water treatment plant (WTP) is required to treat Narmada water for producing specified quality of cooling tower make-up water and boiler feed make up water. A demineralization based water treatment plant has been provided to generate the entire quality of make-up water for cooling tower and boiler feed water of high quality for high pressure from the raw water
5.1.5 Offsite Plant: 1. Ammonia Storage & handling 2. Naphtha storage 3. E.T.P. (Effluent treatment plant) 4. Diesel power generating set (DG SET)
1. Ammonia Storage & Handling:
10,000 tone ammonia storage tank:
10,000 tone liquid NH3 storage tank was built by M/s Vijay tanks & vessels Pvt. Ltd. It is a single wall cylindrical vessel with a fixed self- supporting cone roof & insulated with polyurethane foam. Its diameter is 30m & height is 21.5m. The tank is provided with refrigeration system & sufficient safety gadgets.
52
CHAPTER 6 :- HELTH.HAZARDS AND SAFETY 6.1 Introduction To Industrial Safety:
Safety is becoming very important with every management as it has come to play a very vital role in the modern development. Before many years, accidents were considered as acts of God and nature.
Scientific minded people have analyzed accidents and developed a separate engineering branch of accident prevention. This analysis was required due to
Rising trend of accidents
Increased use of machinery
Increased material handling
Lack of safety standard
Lack of training
Better reporting of accidents
6.2 Safety:
Safe use of man, material and machine by safe system method of work is to achieve zero accidents which results in higher productivity.
6.3 Accident:
An accident is unplanned and unexpected events which interfere or interrupts the planned process of work and results in personal injury.
6.4 Accident Factors:
A personal accident injury occurs as a result of an accident
An accident due to unsafe act and/or unsafe condition
Unsafe act/unsafe condition exists due to fault of persons
Fault of persons are due to negligence. Thus, if we can remove fault of persons we can prevent 98% accidents.
6.5 List Of Safty Equipments:
53
6.5.1 Respiratory Personal Protective Equipments
Self-contained breathing apparatus sets of 30 minutes and 10 minutes
Continuous airline masks.
Trolley mounted self-contained breathing apparatus set 2.5 hours
Canister gas mask. Dust mask/cloth mask. (Air purifying respirator)
6.5.2 Non-Respiratory Personal Protective Equipments
Helmet
Ear muff and ear plugs
Goggles
Face shield
Hand gloves
Aprons
Safety Shoes
Suits
Safety harness
6.5.3 Warning Instruments
Oxygen, carbon dioxide, chlorine, ammonia indicator with replaceable sensors. Explosive meters for measuring explosive range.
Fire fly instrument for confined space entry.
6.5.4 Gas Leakage Protection Installation
Safety Showers
Manual water sprinklers
Communication systems
6.5.5 First Aid Boxes
IFFCO kalol is maintaining the dispensary around the clock at plant over & above we have provided first aid boxes at all shop floor where employees are working 54
6.6 Safety Precautions:
When taking samples of anhydrous ammonia and when operating or working on ammonia valves, equipment containing ammonia such as ammonia feed pumps, operators, laboratory and maintenance personnel must wear overalls, safety goggles and rubber gloves. If any part of the skin has been exposed to ammonia, wash immediately and thoroughly with water.
Work on the ammonia equipment should be done from the upwind side of the equipment to avoid or minimize contact with escaping ammonia.
The location of fire hydrants, safety showers, eyewash fountains ammonia canisters gas mask, emergency air breathing apparatus should be well known to all person.
Instruments containing mercury must not be used if ammonia is likely to come in contact with the mercury.
Heavy leakage of ammonia can be dealt by spraying large quantity of water with spray nozzles.
6.7 Fire Hazards:
The general types of fire are encountered in the process plants. One involves common combustible material such as wood, rags, paper, etc. (Class „A‟ fire s), the
next flammable liquids and gases such as lubrication oils and solvents, ammonia vapors etc. (Class „B‟ fires) and the third involve electrical equipment (Class „C‟
fires).
In general three things are required to make a fire
Something which will burn egg., a combustible material
Oxygen-air
A source of ignition or existence of a temperature at or above which a material will start burning spontaneously.
6.8 Principles Of Fire Extinguishing:
55
Fire may be extinguished by withdrawing of flammable contents, interrupting flammable flow, isolating fuel from air, heat removal to below reaction temperature or by dispersal.
In the event of fire on electrical mains or apparatus, the affected part shall be immediately isolated from its source of supply of electrical energy.
Carbon tetrachloride extinguishers and Carbon dioxide extinguishers are intended mostly for use on electrical fires and may be used on energized electrical equipment without danger to operator provides. They are properly maintaining no moisture.
It is dangerous to throw a stream of water, a wet blanket or a stream from an ordinary soda acid or foam type fire extinguishers on line main apparatus. When found necessary to use them, have all neighboring mains or apparatus made dead.
In case of fire, it is the duty of the operating personnel to protect life and property and to extinguish the fire as quickly as possible.
The greatest cause of fire is welding which may be required during plant operation. It should be a stringent rule of the plant that no welding without permission of the supervisor.
Fire and safety equipment, under conditions of extreme exertion provide protection only for a few minutes. Equipment must be cleaned, replenished and inspected for damage before being returned to service. Equipment should be maintained in excellent condition and inspected frequently so that they are available in case of emergency.
6.9 Color Code For Pipeline:
Green---ordinary hazard
Red---high level hazard
Black---foam 6.4 Fire Fighting Appliances: Type of
Class A
Class B
Class C
Carbon
Suitable for surface
Suitable. Does not
Suitable. Non-
dioxide
fires only
leave residue or
conductor and
extinguisher
56
affect equipment or
does not damage
food stuff.
equipment.
Dry
Suitable for small
Suitable. Chemical
Suitable.
chemical
fire
releases smothering
Chemical is non-
gas and shields
conductor or dry
operator from heat.
chemical shields operator from heat.
Foam
Water
Suitable. Has both
Suitable.
Unsuitable. Foam
smothering effect
Smothering blanket
being a conductor
and wetting action.
does not dissipate,
should not be
floats on top of
used on live
spilled liquid.
equipment.
Suitable. Water
Unsuitable. Water
Unsuitable. Water
saturates material a
will spread and not
being conductor
6.10 Fire Protection:
Segregation buildings, fire resistant walls, flame arrestor, automatic fire extinguishers.
Portable extinguishers, hydrants, sprinklers, fire water and trailer pump, firefighting team and drills.
Safe access for firefighting, protection against lightening and ignition and detailed provisions of fire exists.
Safety from gas cylinders and flammable liquids, dust gas, vapor and waste.
57
CHAPTER 7 :- BAGGING & MATERIAL HANDELING Storage silo with a capacity of 30,000 tones urea has been provided to ensure continuous operation in the event of non-availability of wagons or irregular seasonal demand for the fertilizer. Urea is bagged in polyethylene laminated jute bags. Bagging and material handling plant is a section of the production department. This is the plant where packing of urea product is done in bags and then it is loaded in trucks / wagons and sent to the market.
7.1 Types Of Conveyors, Machines, Heavy Equipments In This Plant
1.
Product conveyor
2.
Silo ingoing conveyor
3.
Silo outgoing conveyor
4.
Dust conveyor
5.
Mini conveyor
6.
Bagging plant conveyor
7.
Hopper conveyor
8.
UBM hopper conveyor.
7.1.1 Conveyors They are made up of 4 ply Dunlop rubber joined by vulcanization. There are carrying rollers, return rollers, idlers, guide rollers and impact rollers. The conveyors are driven by a motor or gear box. There are rope switches for immediate stopping of the belt. There are skirt guards to prevent spillage and scrappers to clean the conveyor belt.
Product Conveyor:
This conveyor is inclined. It takes material from the urea plant and delivers to silo ingoing conveyor or bagging plant conveyor through a flap valve.
Silo Ingoing Conveyor:
This conveyor receives material from the product conveyor through a flap valve and delivers in silo. 58
Silo Outgoing Conveyor:
This conveyor is used to transfer reclaimed material from silo to bagging.
plant conveyor through vibrator screens.
Dust Conveyor:
This conveyor is used to deliver dust received from vibrator screen to silo.
Mini Conveyor:
This conveyor is used to feed material on bagging plant conveyor.
Vibrating Screens:
There are 4 screens to carry out screening of reclaimed material. Screen overflow (good material) is fed to bagging plant conveyor. The screens are manufactured by Pennwalt India Ltd. Screen size is 84”. The screens have a capacity of 26 ton per hours.
Transfer Tower:
The area where product conveyor material is delivered on the bagging plant conveyor tail end and the screens are located is called the transfer tower.
Silo:
It is a go down where urea material is stored. Shape
:
Parabolic
Purpose
:
Storage of loose urea prills
Capacity
:
30000 tons
Length
:
210 meters
Width
:
37 meters
Height
:
18.5 meters
7.2 Detailed Description:
7.2.1 Conveying System:
The conveying section consists of three routes which are listed below: 59
From prill tower to urea storage building.
From urea storage to bagging machines.
From prill to bagging machines.
The control circulation for the control gear provides for remote starting of any of the pre-selected route for prilled urea all the drives of the conveying system are electricity inter locked.
7.2.2 Empty Bag Handling:
Empty bag bales are lifted through two openings in the floor of empty bag store. Bags with the help of two half tones cranes M-2133 A & B and one crane is second empty bag store. Besides lifting the bag bales, these cranes can be used for stacking empty bag bales in empty bag store.
7.2.3 Reclaim Machine:
This machine is used to reclaim the material from the silo and deliver it to the silo outgoing conveyor. The main parts of the reclaim machine are the scrapper bottom, bucket elevator and link conveyor. By using scrapper bottom, material is scrapped and delivered to the buckets from where the material is transferred to the link conveyor from the vertical bucket elevator.
The reclaim machine length of bulk urea storage building. Bulk urea is reclaimed via scrapper, bucket elevator and belt conveyor and discharge on the reclaim conveyor M-2117.travels along the
Process:
There are 6 packer scale (P/S) or Bagging and Weighing machine along with six hoppers. Each hopper has a capacity of 12 Ton. One new P/S known as UBM (Universal Bagging Machine) which is fully automatic has also been installed.
When the machine is stopped, 45kg material is fed in the bucket through opening of two feed gates. Then one gate is closed which has a hole in the centre through which remaining 5 kg material is fed. 60
Then the second gate closes. When the bag is applied to the sock gap assembly, the bottom flapper of the bucket opens and the material is fed in the bag. The bag is then released and it moves on the slat conveyor. Stitching of the bag is done and then the bag falls on the platform through chutes. The bag is then loaded into bucket / wagons or stacked on platform.
Specification Of The Empty Bag
Length
:
915 mm
Width
:
610 mm
Weight
:
130 gm (+ or – 3%)
Material
:
HDPE
Color
:
Milky white with blue ton
Lamination
:
Inside laminations with 100 gauge thick. This is done to protect urea from moisture as it is a hygroscopic material.
Stitching
:
stitching thread green in colour
Strength
:
Width wise
Bottom seam
:
32 kgf
Fig.7.1: Urea Bag
61
Rail tanker loading:
The surplus liquid NH3 from tanks is dispatched to IFFCO (Kandla Unit) through rail tankers. For loading into rail tankers, five loading points are provided. At a time batch of five tankers wagons, each having capacity of 32 tone can be loaded to NH3 loading pumps each having discharge capacity o f 105 tone/hr at a pressure of 21.00 kg/cm2 are installed.
Refrigeration system:
The NH3 storage tanks are fully & designed for maximum boil off of 0.04% per day. Vapor pressure of NH3 is high even at atmospheric condition. To maintain nearly atmospheric pressure in tank, the vapour generated has to be condensed. This is done by taking the generated vapour from storage tank to the refrigeration system where the vapour are compressed, liquefied & returned to the tank in liquid form.
One refrigeration compressor having capacity of 540 kg/hr was installed with 10,000 tone NH3 storage tank. Two more NH3 refrigeration compressors having identical capacity were added with installation of 5000 tone NH 3 storage tank. These three refrigeration compressors are integrated to draw vapour from both the storage t anks. Also 150 mm NB pipe line is provided to take about 200 kg/hr vapour from both the storage tanks to NH3 plant refrigeration system through pressure control valve.
7.3 Effluent Treatment & Disposal:
Approximately 18000m3/day of raw water is utilized at IFFCO kalol mainly for process water & boiler feed
water generation. Effluent treatment facilities have
3 3 been installed to handle the 3500-4000m /day bulk & 50-600m /day strong effluent coming out of various out of various plants every day.
Equipment specification:
Strong effluent tanks
Bulk effluent tanks 62
Balancing ponds
Effluent pit
H2SO4 storage tanks
Effluent treatment system is installed to control the undesirable element in the liquid effluent before discharging outside IFFCO premises.
Effluent discharge outside IFFCO should statutory requires norms imposed by state & central pollution control boards.
7.4 Types Of Liquid Effluent:
The total effluent generated within the plants is divided into t wo categories & treated separately
Strong effluent: - Having higher concentration of dissolved compounds.
Bulk effluent: - Having comparatively less amount of concentrated dissolved solids.
This effluent is collected either into strong effluent tanks or bulk effluent tanks. Water from urea plant
drains & washing is
collected
in separate tanks known as
balancing ponds diverted to bulk or strong effluent as per its analysis.
Strong effluent & disposal:
The concentrated effluent from water plant is collected in strong effluent tank & discharged to solar evaporation lagoons inside IFFCO premise with the help of strong effluent pumps. Nearly 600m3/day of strong effluent is generated, collected in strong effluent storage tanks, mixed & then pumped to polythene lined solar evaporation lagoons having area about 15 hecters.
Bulk effluent treatment & disposal:
Effluent water containing comparatively very low concentration of pollutant is called bulk effluent. The effluent from following source is collected in bulk effluent storage tank.
Water treatment plant with low concentration of salts
Inert gas generation plants 63
Cooling water blow down From hydrolyser system during upset condition Sand filter backwash oil separator Domestic effluent HCL fumes scrubber water Open channels domestic water collected at effluent pit is diverted to bulk effluent. Bulk effluent segregated from the water treatment plant is collected only in bulk effluent tank B & allowed to mix into tank A for better neutralization effect. Weak effluent collected & mixed in weak effluent storage tanks to form bulk/combined effluent. Bulk effluent elements are controlled by adjusting the dilution water flow in normal operation. About 3000m3/day combined effluent is pumped outside IFFCO premise. The effluent quality is continuously monitored within plant before final discharge to meet statutory requirement of pollution control board.
64
CHAPTER 8 :- ENVIROMENT & POLLUTION CONTROL It accepts its duty to exercise care for health of employees & others which may be affected by operation & pollution. It gives equal importance to pollution control as any other activity.
8.1 Air Pollution:
The main source of air pollution from ammonia plant at IFFCO kalol are emition from stack of furnaces & boiler.
Primary reformer
Secondary reformer
Boiler
The concentration of sulphur being negligible in the RLNG & associated gas obtained from nearby well & flue gas remains below specified limit. However unit has SO 2, NOx, CO analyzer for analyzing flue gas quality of ammonia plant & utility 8.2 Solid Waste:
Waste means any substance which constitute scrap material or an effluent oran other unwanted surplus sub. arising from app. o f any process
In ammonia plant at kalol mainly two types of solid waste are generated
Spent catalyst from plant
ETP sludge
8.2.1 Disposal Of Solid Waste:
Spent catalyst are stored in drum & sell too gather company who has GPSB authorized
ETP sludge collected from strong effluent tank mainly salt of Ca & Mg are filled in bags & damped in GPSB approved site
Waste can also be removed by other methods like dilution ,incineration, bioremediation, stabilization
8.3 Water & Noise Pollution: 65
To control the water pollution a centralized effluent treatment plant is installed. All the streams are collected in pond. After treatment & confirming by GPSB norms & s tandards it is discharged outside plant premise this water is utilized by farmers for irrigation Mainly 18000m3/d Narmada water is utilized in plant for process water & boiler feed water generation. effluent facilities have been installed to handle 3500-4000m3/d bulk & 500-600m3/d strong effluent coming out of various plants every day
ETP contains
Strong effluent tanks
Bulk effluent tanks
Balancing ponds
Effluent pit
H2SO4 storage tanks
ETP is installed to controlled the undesirable element in the liquid effluent before discharging outside IFFCO
66
