This document provides an overview of the IFFCO Aonla Unit, including its power generation, offsite plants, ammonia plant, and urea manufacturing processes. It describes the key components of the power plant like the gas turbine generator, compressor, combustion system, and turbine. It also summarizes the various offsite plants that support production, such as the raw water system, water treatment plant, cooling towers, and effluent treatment plant. The document contains flow charts and descriptions of the ammonia and urea production processes.

1. 1
AONLA UNIT
Project report submitted for the requirement vocational training
For
AMMONIA PLANT II , PH PLANT II
B. TECH IN MECHANICAL ENINEERING
Submitted to Submitted by
MR. HARISH RAWAT Dheeraj kumar
(CHIEF MANAGER TRAINING ) ROLL NO:-19ME21
Training and Development Department VT NO :- 126
(IFFCO AONLA) BAREILLY Duration Date :-07/06/2022-22/07/2022
DEPARTMENT OF MECHANICAL ENGINEERING
IET M J P ROHILHKHAND UNIVERSITY BAREILLY
(2022-2023)

2. 2
CERTIFICATE
This is to certify that DHEERAJ KUMAR Student of Dept of Mechanical Engineering
, IET M. J. P. ROHILKHAND UNIVERSITY BAREILLY ( Vocational Training
no.126 ) B.Tech-3rd
Year Mechanical Engineering has undergone an industrial training
at INDIAN FARMERS FERTILIZERS CO-OPRATIVE LTD.(IFFCO) AONLA ,
BAREILLY from 07st
June 2022 to 22th
July 2022. He has appeared in industrial training
and viva voce as a partial fullfillment of requirement for the award of degree of Bachelor of
Technology in Mechanical Engineering.
Mr. Harish Rawat
(Chief Manager training )
(Training and DevelopmentDepartment )
IFFCO Aonla ,Bareilly

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CONTENTS :-
 Acknowledgement
 Preface
 Contents
 About IFFCO
 AONLA Unit
1.Introduction
 POWER GENERATION
 THE COMPRESSOR
 THE COMBUSTION SYSTEM
 THE TURBINE
 HEAT RECOVERY STEAM GENERATONS (HRSG)
 DEAERATOR
 ECONOMIZER
 BOILER
 PRIMARY AND SECONDARY SUPER HEATERS (PSH AND
SSH)
2.OFFSITE PLANTS
 RAW WATER SYSTEM
 WATER TREATMENT PLANT
 COOLING
 EFFLUENT TREATMENT PLANT
 INSTRUMENT AIR PLANT
 INERT GAS GENERATION PLANT
 AMMONIA STPRAGE PLANT
3. AMMONIA PLANT
 FLOW CHART OF AMMONIA PLANT
 UREA MANUFACTURING
4. PROCESS IN PLANT
 ONCE – THROUGH UREA PROCESS
 PARTIAL RECYLE PROCESS
5. STRIPPING PROCEES BAED PLANTS
 SATAMICARBON STRIPPING PROCESS.
 ACES PROCESS
 SELECTION OF THE PROCESS

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 PROCESS DESCRIPITOMN
6. UREA PLANTS FLOW CHART
 UREA SYNTHESIS
 HIGH PRESSURE STRIPPER
 HIGH PRESSURE CONDENSATION AND SEPARATION
 MEDIUM PRESSURE SECTION
 LOW PRESSURE SECTION
 VACUUM CONCENTRATION
 PROCESS CONDENSATE TREATMENT
 UREA PRILLING
7. NEEM COATING OF UREA
 ADVANTAGES OF THE NEEM COATED UREA CAN BE
ENUMERATED AS FOLLOWS
8. OXYGEN PLANT IN IFFCO AONLA
9. UREA PRODUCT QUALITY
 Controlling agency
 Safety Aspects
 Accident factors
 Safety Precaution
 List of safety equipment
1. respiratory protective equipment
2. non—respiratory protective equipments
3. warning Oinstrument
4. Gas Leak Instruments

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ACKNOWLEDGEMENT
It is my great pleasure to express my sincere gratitude to
Mr. Harish Rawat (Chief Manager Training and Development) Section, IFFCO,
Aonla Unit for his deep interest profile inspiration, valuable advice during the
entire course of vocational training.
I wish to express my gratitude to the Mechanical Engineering
(ROTATING MACHINERY) of INDIAN FARMERS FERTILIZERS
COOPERATIVE LIMITED for allowing me to study various functions of their
department.
It gives me an opportunity to understand the practical aspects of different
functions of Mechanical Engineering (ROTATING MACHINERY) of
INDIAN FARMERS FERTILIZERS COOPERATIVE LIMITED. The
present project bears the true justification of their investment. I would like to add
few heartfelt words for the people who were part of this project in numerous ways.
I express my sincere gratitude to ASHISH KUMAR (CHIEF TECHNICIAN IN
MECHANICAL ENGINEER),for accepting me as a student summer training &
extending his full support & co-operation throughout the project works.
My overiding dept. continues to be the faculty members of our respected college
for extending their unflinching help & guidance.
For all this I would like to convey my wholehearted thanks to those entire people
who helped me directly & indirectly completing my report.

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PREFACE
This project gives Rich insight about the various measurement & controlling
techniques of IFFCO AONLA & also about various facilities provided by the
company to its customers.
Moreover this project will also help in learning Practical Aspects of
different functions of Mechanical Department which are very necessary to become
a good Mechanical engineer.

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1.INTRODUCTION IFFCO AONLA
Indian Farmers Fertiliser Cooperative Limited (IFFCO) is one of India’s biggest
cooperative society which is wholly owned by Indian Cooperatives.
Founded in 1967 with 57 cooperatives, we are today an amalgamation of over
36000 Indian Cooperatives with diversified business interest ranging from General
Insurance To Rural Telecom apart from our core business of manufacturing and
selling fertilisers.
Total Production
84.79 Lakh MT
Cooperative Members
Over 36,000
FIGURE..1
The total Urea Production from IFFCO AONLA Complex was 46.75 Lakh MT out
of which 6.32 Lakh MT is from AONLA I and 9.92 Lakh MT from AONLA II in
the FY 2019-20

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PRODUCTION CAPACITY
AONLA- I
Plant Process Licensor Annual Capacity (MT)
Ammonia MW Kellogg, U.S.A. 4 lakh MT
Urea Snanprogetti, Italy 7 lakh MT
AONLA-II
Plant Process Licensor Annual Capacity (MT)
Ammonia Haldor Topsoe AS, Denmark 5.7 lakh MT
Urea Snanprogetti, Italy 10 lakh MT
 Properties of Urea:
• Structure:
• Physical & chemical properties of urea
Molecular weight 60.05
N2 Content( %) 46.6
Melting Point 132.7
Sp. Gravity 1.355

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Color White
Heat of solution in water -57.8 Cal./gm
Critical relative Humidity
20o
C 81%
30o
C 73 %
Viscosity at 150°C 2.16 CPS
Crystallization Heat 47.0 Kcal/Kg
Fusion Heat 59.95 Kcal/Kg
Specific Heat (Cal/gm/°C)
20o
C
0.32
 Uses of Urea:
• Agriculture:
More than 90% of world industrial production of urea is destined for use as a
nitrogen-release fertilizer. Urea has the highest nitrogen content of all solid
nitrogenous fertilizers in common use. Therefore, it has the lowest transportation
costs per unit of nitrogen nutrient.
 Action of Urea in Soil:
Many soil bacteria possess the enzyme urease and the following reaction occurs:
UREA + UREASE ⟶ AMMONIA MOLECULES + CARBON DIOXIDE
Thus urea fertilizers are very rapidly transformed to the Ammonium form in soils.
Ammonium and nitrate are readily absorbed by plants, and are the dominant sources
of nitrogen for plant growth. Urea is highly soluble in water and is, therefore, also
very suitable for use in fertilizer solutions (in combination with ammonium nitrate:

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UAN), e.g., in 'foliar feed' fertilizers .For fertilizer use, granules are preferred over
prills because of their narrower particle size distribution, which is an advantage for
mechanical application.
• Explosive:
Urea can be used to make UREA NITRATE, a high explosive that is used
industrially and as part of some improvised explosive devices.
• Chemical Industry:
Urea is a raw material for the manufacture of many important chemical compounds,
such as:
 Various plastics, especially the UREA-FORMALDEHYDE
RESINS.
 Various adhesives, such as urea-formaldehyde or the ureamelamine-
formaldehyde used in marine plywood.
• Potassium cyanate, another industrial feedstock.
IFFCO AONLA UNIT -2 :
Iffco’s Aonla unit is the country’s first unit to convert naptha feed to RLNG feed .
Aonla unit 2 contain steam and power plant ,water treatment plant, cooling tower
,inert gas generation ,ammonia storage and handling ,effluent treatment plant.
• POWER GENERATION
Power Generation in IFFCO is done by GASTURBINE GENERATOR
(GTG)The power plant is designed to produce 18 MW of power at 11 KV, 50 HZ.
The power is produced by a turbo generator, driven by steam turbine. The whole
package has been supplied by BHEL, Hyderabad. The steam turbine uses steam at
115 kg/cm2 and 515 deg. C as the motive fluid and is an extraction cum condensing
turbine. The TG set is DCS controlled.. GasTurbine Generators basically involve
three main sections:

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• The compressor, which draws air into the engine, pressurizes it, and
feeds it to the combustion chamber at speeds of hundreds of miles per hour.
• The combustion system, typically made up of a ring of fuel injectors that
inject a steady stream of fuel into combustion chambers where it mixes with
the air. The mixture is burned at temperatures of more than 2000 degrees F.
The combustion produces a high temperature, high pressure gas stream that
enters and expands through the turbine section.
• The turbine is an intricate array of alternate stationary and rotating aerofoil-
section blades. As hot combustion gas expands through the turbine, it spins
the rotating blades. The rotating blades perform a dual function: they drive
the compressor to draw more pressurized air into the
combustion section, and they spin a generator to produce electricity .
.
FIGURE..2 – POWER GENERATION

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First air from atmosphere is compressed in compressor then compressed air enters
in combustion chamber along with a fuel (In IFFCO fuel that is commonly used now
a days is Natural Gas). After combustion the mixture of gases acquires a very high
temperature and a high pressure then it rotates the turbine, from turbine we get
electricity.
So, now we have two options: o Exhaust gases of turbine at a temperature of about
500°C could be vented into atmosphere.
o We could also utilize the energy of these gases to generate steam. If we follow
first case efficiency of our plant would be about 27% and if we follow second
one, efficiency of our plant would be 87%. So, IFFCO follows the second
process. There is also a stack for the gases to exhaust that is being used in
case of any problem in Heat Recovery Steam Generating Units (HRSG).
HEAT RECOVERY STEAM GENERATORS (HRSG)
To the stream 4 in the above flow chart a HRSG unit is connected to utilize the
heat contained in the exhaust gases by converting water into HIGH PRESSURE
STEAM. Exhaust gases of HRSG is vented to atmosphere through stacks. Gases
enters in HRSG units are not sufficiently heated so as to obtain high pressure
steam. So, Heaters are provided in the HRSG units through which we obtain
desired temperature in the HRSG units.
The water that enters in the HRSG units to get converted into High Pressure Steam
, first passed through Deaerator then, through BOILER FEEDWATER PUMP
(BFW) water is pumped to HRSG units and boiler.
DEAERATOR: Deaerator is a device that is used to remove mainly Oxygen and
Carbon Dioxide from feed water of plants. Dissolved oxygen in boiler feed water
causes corrosion damage in steam systems by attaching to the walls of metal piping

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and other metallic equipment and form oxides (rust). Dissolved Carbon Dioxide
forms carbonic acid which further leads to corrosion (rust).
The plant also contains a Steam Generator (SG) unit to generate HP steam.
Components of Steam Generator:
DEAERATOR
ECONOMIZER:
An Economizer for a heat recovery steam generator utilized to improve the
efficiency of the Rankine cycle by preheating the water that flows to the evaporator
section.
BOILER:
This section simply contains two drums and two tubes connecting them. Two drums
are WATER AND MUD DRUMS. Water (Steam) through these tubes due to
Density Difference that is due to Temperature Difference.

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PRIMARY AND SECONDARY SUPER HEATERS (PSH AND SSH):
This section has been connected after boiler and the output of secondary super heater
is the high pressure steam. The heat required in these heaters is given by the
combustion of natural gas (NG) as shown in the above flow chart.
2. OFFSITE PLANTS
Offsite Plants are to support production plants. Without offsite plants, production
plants have no existence. So, offsite plants are of great importance.
Following are the plants come under offsite section:
o Raw water system
o Water Treatment Plant (Demineralized Water Plant )
o Cooling Towers
o Effluent Treatment Plant
o Instrument Air Plant
o Inert Gas Generation Plant
o Ammonia Storage Plant
o RAW WATER STORAGE
Water obtained from natural sources like rivers, lakes, ponds or sub soil water is not
fit for use directly as boiler feed water, modern high pressure boilers need feed water
which should be of high degree of purity and conditioned with certain chemicals.
The surface water is generally more turbid but has comparatively less dissolved salts.
The underground water is well filtered under the crests of earth and turbidity from 2
to 5 ppm on silica scale but dissolved salts are more and sometimes render the water
useless for industries without proper treatment. Thus surface water, if available in
plenty is preferred because of its purity and less laborious treatment.
In IFFCO underground sub soil water is the only source of raw water.
Raw water from raw water storage is used for following purposes:
-In Water Treatment Plant

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-Cooling Water Make Up
-For Fire Protection System
-For Cleaning Plant Area
-For Drinking Purpose
o DEMINERALIZED WATER PLANT
Underground water specifications:
• Turbidity – 5 ppm
• Total alkalinity – 424 ppm as CaCO3
• Total Hardness – 348 ppm as CaCO3
• Iron - 0.06 ppm as Fe
• TDS – 650 ppm
• Silica – 16 to 33 ppm as SiO2
• PH – 7.8
The water that could be used in Plant (D. M. Water) should have following
specifications:
• PH – 6.8 to 7.3
• Silica < 0.02 ppm
• Total Electrolytes – 0.1 ppm (Max)
• Hardness – Nil
Flow chart of DM Plant is given below:

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FIGURE..3 – DM PLANT
o COOLING TOWERS
Most of the units of any chemical plant are Heat Exchangers (may be condenser,
Boiler or Evaporator). So, every heat exchanger requires a cold fluid to absorb heat
and one hot fluid to release heat. In most of the heat exchangers cold fluid is water
and the plant to cool water is called cooling tower.
Cooling Tower is also a type of heat exchanger and in IFFCO heat absorbing fluid
is air and heat releasing fluid is water. So,water cools down in this process.
FIGURE..4 - A VIEW OF COOLING TOWERS OF IFFCO

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Round shapes in the above photo at the top are Induced Draft (ID) Fans. ID Fans
suck air from atmosphere passes it through water, so air comes in contact with water
and heat transfer takes place as a result of which water cools down.Chlorine (stored
in yellow tanks) is also mixed in water to kill bacterias and to increase its purity
level. Hydro Chloric acid and Hydrogen Sulphate are also mixed to maintain PH of
water.
o EFFLUENT TREATMENT PLANT
Effluent treatment plant is for the treatment of waste water of Ammonia and Urea
Plant. Waste water contains a little bit ammonia, salts and several other impurities.
The flow chart of Effluent Treatment Plant is given below:
FIGURE..5 – FLOW CHART OF EFFLUENT TREATMENT PLANT
In the air stripper air comes in at bottom and comes out with impurities at top. In
the steam stripper steam comes in at bottom and comes out with impurities at top.

18. 18
o INSTRUMENT AIR PLANT
The plant is designed to produce 3000 M3/hr of dry air. This is split flow no loss
type air drier. Supplier for this drier is M/s Gaso Energy Systems (India) Pvt. Ltd.
Pune.
Atmospheric air can’t be used directly to open and close valves because it contains
moisture and many other impurities that could cause corrosion and could kill the life
of valves. So, Air used in plants is moisture and impurities free and is known as
instrument air. Instrument air is in use in each of the plants and is kept in green color
tanks in every plant.
Flow chart of Instrument Air Plant is given below:
FIGURE..6 – INSTRUMENT AIR PLANT
o INERT GAS PLANT
In this plant inert gas (N2) is generated, which is used for purging and for Production
of Ammonia in Ammonia Plant.

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FIGURE..7 – INERT GAS PLANT
Cold box (cuboidal Box) contains there units:
• Heat Exchanger
• Expansion Turbine
• Condenser
FRACTIONAL DISTILLATION:
Fractional Distillation is the method of separating two fluids on the basis of their
boiling points. Because Nitrogen is most light here so, we get Nitrogen at the top in
the gaseous form.
AMMONIA STORAGE
Ammonia is stored in Ammonia storage tanks so that in case of any problem in the
Ammonia Plant, Ammonia could be supplied from these tanks. Ammonia is stored
at a gage pressure of 400 mm water at a temperature of -33°C in liquid form.
Gaseous Ammonia iscontinuously returned back to Ammonia Plant.

20. 20
3. AMMONIA PLANT
Ammonia is a important raw material to manufacture Urea. Ammonia is
manufactured in Ammonia Plant. Ammonia plant is based on HALDOR TOPSOE
TECHNOLOGY. To manufacture ammonia, we need hydrogen and nitrogen in
gaseous form. We get Nitrogen from Inert Gas (From Atmosphere) plant and
hydrogen from Natural Gas. Natural Gas is supplied at the battery limit by GAS
AUTHORITY OF INDIA LIMITED (GAIL) from gas wells located in Bombay
through HAZIRA-BIJAPUR-JAGDISHPUR (HBJ)
Pipeline. GAIL has plans to set up certain facilities for extraction of higher
hydrocarbons from the gas due to which the gas would become leaner.
Properties of Rich and Lean Gas (Gas by GAIL)
Component RICH(%) LEAN (%)
Methane 78.84 98.39
Ethane 7.23 1.40
Propane 4.59 0.10
i-butane 0.88 -
n-butane 1.10 -
i-pentane 0.26 -
n-pentane 0.24 -
Hexane 0.26 -
Carbon dioxide 6.49 -
Nitrogen gas 0.01 0.10
Oxygen 0.10 0.01
To get the Ammonia manufactured, the following steps should be followed:

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• Desulphurization
• High Pressure Catalytic Reforming
• Water Gas shift reaction
• Carbon Dioxide absorption and stripping
• Ammonia Synthesis
• Refrigeration
FLOW CHART OF AMMONIA PLANT :-
FIGURE..8 – FLOW CHART OF AMMONIA PLANT

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UREA MANUFACTURING
• REACTIONS:
Urea is produced from ammonia and carbon dioxide in two equilibrium
reactions:
2NH3 (Liq.) + CO2 (g) ⥨ NH2COONH4 Exothermic Reaction
(Ammonium
Carbamate)
NH2COONH4 ⥨ NH2CONH2 + H 2O Endothermic Reaction
(Urea)
Overall reaction is Exothermic.
Reaction 1 is favored when solution pressure is greater than decomposition pressure.
Decomposition pressure is the pressure at which carbamate decomposes into
ammonia and carbon dioxide.
Decomposition pressure is a function of concentration of Ammonia and temperature.
The urea manufacturing process, is designed to maximize these reactions while
inhibiting biuret formation:
2NH 2CONH 2 ⥨ NH 2CONHCONH2 + NH3
(Biuret)
This reaction is undesirable, not only because it lowers the yield of urea, but because
biuret burns the leaves of plants. This means that urea which contains high levels
of biuret is not suitable for use as a fertiliser.
• Uses of Urea
• More than 90% of urea world production is destined for use as a fertilizer
• A raw material for the manufacture of plastics, to be specific, Urea –
formaldehyde resin.

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• A raw material for the manufacture of various glues ( urea— formaldehyde
Or urea melamine—formaldehyde); the latter is waterproof and is used For
marine plywood.
• A flame—proofing agent ( commonly used in dry chemical fire
extinguishers As urea potassium bicarbonate).
• A reactant in some ready-to-use cold compressors for first-aid use, due to
The endothermic reaction it creates when mixed with water.
• A cloud seeding agent, along with salts, to expedite the condensation of
water In clouds, producing precipitation .
• Feed for hydrolyzation into ammonia which in turn is used to reduce
emissions From power plants and combustion engines.
PROCESS IN PLANT (selection)
Several processes are used to urea manufacturing. Some of them are used
conventional Technologies and others use modern technologies to achieve high
efficiency. These Processes had several comparable advantage and disadvantage
based on capital cost, Maintenance cost, energy cost, efficiency and product quality.
Some of the widely used urea production processes are.
1.Once-Through Urea Process
It is a conventional process in which the unconverted carbamate is decomposed to
NH3 And CO2 by heating the urea synthesis reactant effluent mixture at low
pressure. The NH3and CO2 is separated from the urea solution and utilized to
produce ammonium Salts by absorbing NH3. Advantage
• Simple process Disadvantage
• Large quantity of ammonia salt formed as a co product
• Overall carbon dioxide conversion is low
• High production cost
• High energy cost
• High environment pollution
2 .Partial Recycle Process

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• Part of the off gas is recycled back to the reactor
• The amount of ammonia is reduced to 15% to that of once-through that must
be used in other process
• High CO2 conversion
• High energy cost
• High environmental pollution
• High production cost
FIGURE..9-FLOW CHART OF PARTIAL RECYCLE PROCESS

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Typical partial recycle urea process
3 .Stripping Process Based Plants (Internal carbamate recycle)
The unreacted carbamate and the excess ammonia are stripped from the urea
Synthesis reactor effluent by means of gaseous CO2 or NH3 at the reactor Pressure,
instead of letting the reactor effluent down to a much lower Pressure. The NH3 and
CO2 gas recovered at reactor pressure, is condensed And returned to the reactor by
gravity flow for recovery.
A.Snamprogetti Process (Italy)
• Synthesis and high pressure (HP) recovery (154 bar)
• Medium pressure (MD) purification and recovery (18 bar)
• Low pressure (LP) purification and recovery (4.5 bar)
• Vacuum concentration ( 2 steps: 0.3 and 0.03 )
• Process condensate process
• Finishing: prilling and granulation
FIGURE..10- Snamprogetti urea process

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B. Stamicarbon CO2 Stripping Process :
NH3 and CO2 are converted to urea via ammonium carbamate at a pressure of
140 bar and a temperature of 180−185 C°, an NH3:CO2 molar ratio of 3:1 is
Applied. The greater part of the unconverted carbamate is decomposed in the
Stripper, where ammonia and carbon dioxide are stripped off using CO2 as stripping
agent. The stripped off NH3 and CO2 are then partially condensed and recycled to
the reactor. The heat evolved from this condensation is used to
FIGURE..11-stamicarbon CO2 stripping process
produce 4.5 bar steam some of which can be used for heating purpose in the
downstream sections of the plant. The NH3 and CO2 in the stripper effluent are
vaporized in 4 bar decomposition stage and subsequently condensed to form
acarbamate solution. Further concentration of urea solution takes place in the

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Evaporation section, where 99.7% of urea melt is produced. Figure stamicarbon
CO2 stripping process
C. (ACES Process )
ACES ( Advanced Process for Cost and Energy Saving ) process has been
developed by Toyo Engineering Corporation. Its synthesis section consists of the
reactor, stripper, two parallel carbamate condensers and a scrubber all operated at
175 bar. The reactor is operated at 1900 C° and an NH3:CO2 molar feed ratio of
4:1.
Its consist of five main sections
• Synthesis section
• Purification section
• Concentration and prilling section
• Recovery section
• Process condensate treatment section
• Selection Of The Process
Snamprogetti ammonia-stripping urea process is selected because it involves
a High NH3:CO2 ratio in the reactor, ensuring the high conversion of
carbamate to urea. The highly efficient ammonia stripping operation
drastically reduces the recycling of carbamate and the size of equipment in
the carbamate decomposition. Snamprogetti differs from other methods in
being based on The use of excess ammonia to avoid corrosion as well as
promote the Decomposition of unconverted carbamate into urea. The success
of any urea manufacture process depends on how economically we can
recycle carbamate to the reactor.
NH2COONH4(s) = 2NH3(g)+CO2(g) ΔH= +37.4 kcal/gmmol
This reaction involves increase in volume and absorption of heat. Thus this
Reaction will be favored by decrease in pressure and increase in temperature
Moreover decreasing the partial pressure of either of the products will also

28. 28
favor the forward reaction. The process based on increase/decrease of partial
pressure of NH3 or CO2 is called stripping process. According to the above
equation we have:
K= (PNH 3) 2*(PCO 2)[where, K= equilibrium constant]
The stripping is effected at synthesis pressure itself using CO2 or NH3 as
Stripping agent. If CO2 is selected, it is to be supplied to the decomposer
/stripper as in stamicarbon CO2 stripping process. While if NH3 , is to be
obtained from the system itself because excess NH3 is present in the reactor
as in snam's process. At a practical temperature K is constant so when (PNH3
) is reduced to keep K constant, carbamate will reduce much fast
decomposition as (PNH3 ) appear in the equilibrium equation with a power
of two. Selection of 1st decomposition should be in such a way that
minimum water evaporates because the recovered gases go along with the
carbamate to reactor again and if water enters reactor production will be
effected adversely due to hydrolysis of urea.
So , stage wise decomposition of carbamate is done.
Process Description
The Snamprogetti urea process is known worldwide.
The process is divided into six sections:
• Synthesis and high pressure (HP) recovery
• Medium pressure (MP) purification and recovery
• Low pressure (LP) purification and recovery
• Vacuum concentration
• Process condensate treatment
• Finishing: prilling

29. 29
FIGURE..12-UREA PLANT FLOW CHART
Urea is manufactured by direct synthesis of gaseous CO2 and liquid NH3.
The process consists of following operations:
 Urea Synthesis
 High Pressure Recovery
 Medium Pressure Recovery
 Low pressure Recovery
 Urea Concentration
 Waste Water Treatment
 Urea Prilling
• UREA SYNTHESIS
Both the raw materials are supplied by ammonia plant. Liquid Ammonia along with
carbonate solution pumped in the reactor at bottom. CO2 along with atmospheric air
in also pumped in reactor.

30. 30
FIGURE..13-UREA REACTOR
Oxygen in the air (supplied with carbon dioxide) forms a passive oxide layer on the
insides of vessel surfaces to prevent corrosion by carbamate and urea. The Reactor
product contains 38 % by weight Urea.
• HIGH PRESSURE STRIPPER
Urea enters the tube of HP Stripper operating at 147 atm/190 °C which is falling
type heat exchanger. The stripper tubes are provided with liquid dividers also called
ferrules. Urea reactor supplies a mixture of urea, ammonia, carbon dioxide, water
and carbamate. In the HP Stripper unconverted is converted into ammonia and
carbon dioxide by using Henry’s Law.
HENRY’S LAW in HP stripper:

31. 31
Excess of ammonia is passed due to which partial vapour pressure of ammonia
increases, by Henry’s law concentration of ammonia should increase in solution that
could only be achieved by decomposition of ammonium carbamate.
Following reaction occurs in HP stripper:
NH 2COONH 4 ⥨ 2NH 3 (Liq.) + CO 2(g)
• HIGH PRESSURE CONDENSATION AND SEPARATION
Gases from high pressure stripper enter in HP Carbamate condenser in
which most of the ammonia and carbon dioxide reacts to form ammonium
carbamate. Condensate from HP Carbamate condenser is passed to HP
Carbamate Separator which passes liquid carbamate again to Urea
Reactor and urea to MP Decomposer.
• MEDIUM PRESSURE SECTION
The MP Decomposer consists of three parts. The top part is MP Separator, the
middle is MP Decomposer and bottom one is MP
Urea solution holder. The urea from stripper is let down to 18 atm from 147 atm. As
a result of pressure let down somesolution flashes, producing vapors of ammonia
carbon dioxide and water. The heat of vaporization is taken from 207 to 140 °C.
This solution is then distributed over bed of pall rings in the MP Separator. The
vapors rising from the MP Decomposer below come into intimate contact. Thus
more carbamate is decomposed by hot vapors. These vapors now filled out of MP
Condenser. The MP Absorber consists of two sections. The top section sis called the
rectification section and the bottom portion is called absorber section. The liquid
and vapor mixture from medium pressure condenser enters the absorber portion of
MP absorber comes out through a sparer. A liquid level is always maintained above
the sparer to absorb vapors of ammonia carbon dioxide and water. The purpose of
this section is to partially strip out the reactants, ammonia and carbon dioxide from

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the urea solution and, after their condensation in water, to recycle the obtained
solution to the reactor, together with the ammonia and carbon dioxide aqueous
solution resulting from the downstream sections of the plant. The ammonia excess
is separated in this section and recycled to the reactor separately. A distillation
column is provided for this purpose. The operating pressure is 17 bar g. A particular
feature is included in this section. Ammonia and carbon dioxide are partially
condensed in the shell of a preheater within the vacuum section, thus recovering
some energy in the form of 200kg of steam per ton of urea. Another particular
characteristic of the MP section is the washing of the so-called inerts (CO, H2 and
CH4 contained mainly in the carbon dioxide and the passivation air). As already
emphasized, the quantity of passivation air in the Snamprogetti technology is very
small (one third compared with other technologies). It is therefore easy to recover
ammonia from the inerts without the risk of explosion mainly due to H2/O2
mixtures. No hydrogen removal from carbon dioxide is required.
• LOW PRESSURE SECTION
Further stripping of ammonia and carbon dioxide is made in the LP section,
operating at 3.5 bar g. The vapors, containing ammonia and carbon dioxide, are
condensed and recycled to the reactor via the MP section. An appropriately sized
tank is provided in this section to collect all the solutions from the plant when it is
shut down for long time. Therefore, in no circumstances are solutions discharged
from the plant.
• VACUUM CONCENTRATION
The urea solution leaving the LP section is about 70% b.w. and contains small
quantities of ammonia and carbon dioxide. The final concentration of the urea
solution (99.8% b.w.) is made under vacuum in two steps at 0.3 and 0.03 bar abs.
for the prilled product, and in one or two steps for the granular product, according
to the granulation technology chosen. An important feature of this section is the pre
concentration of the urea solution to about 86% b.w. The necessary heat is provided

33. 33
by partial condensation of the vapors (ammonia and carbon dioxide essentially) from
the MP section evaporator. Particular care is taken in the design of this section to
minimize temperatures and residence times so as to keep the biuret at minimum
values. A simple solution has been found to the problem of lump formation in the
second vacuum separator: lump formation is prevented by wetting the internal walls
of the separator by means of a small recycle of molten urea.
• PROCESS CONDENSATE TREATMENT
The excellent result achieved by Snamprogetti Technology in the treatment of
waste water from urea plants has received worldwide recognition.All possible
and convenient heat recoveries have been introduced into this section in order to
minimize energy consumption.
• UREA PRILLING
Prilling is the easiest technology tomanufacture solid urea with commercially valid
chemical and physical characteristics. Molten urea (99.8% b.w.) is sprayed at the
top of the prilling tower, at a height of 55-80 m(may be more), according to climatic
conditions; at the bottom, essentially spheroidal urea particles ,namely prills, are
collected and sufficiently cooled in order to be sent to storage ordirectly to the
bagging section without screening, coating or any other treatment. In a few plants
based on the Snamprogetti technology, plant owners have requested that

34. 34
formaldehyde (0.2-0.3% b.w.) be addedto the molten urea just before the prilling
section in order to improve the free-flowing characteristics of the prilled urea and to
achieve a slight increase in hardness. Arising draught of air inside the prilling
toweris the cooling medium that removes thesolidification heat and cools the prills.
The prilling process, although it is a simpleone, conceals some critical problems:
• The bucket must be specially designed tolimit the quantity of fine and
oversize prills to a negligible value. In fact, theGauss distribution curve must be
asnarrow as possible to avoid severe cakingproblems in storage;
• Too much air can cool the product excessively resulting in undesirable
absorption of humidity from the air inhumid climates, again with possible serious
product caking problems in storage;
• Too much air can entrain too much urea dust at the top of the prilling tower.
This last problem constitutes an increasein consumption of specific raw materials
,which not only means plant inefficiency, but principally represents a serious
pollution problem. With regard to urea dust, Snamprogetti has its patented dedusting
system, already applied in some plants,which is able to reduce urea dust from 40
to15 mg/Nm3 of air. In the case of ammonia,the problem is not so easily solved due
to theextremely low partial pressure of ammoniain the air from the prilling tower.
As for the abatement of ammonia, the only possiblemethod is to wash the air with
slightly acidified water.
Unfortunately, dueto the large quantity of air, such a system has a rather high
investment cost as well asa considerable operating cost. Snamprogetti has patented
and applied a very simplesolution in one plant that consists ofthe addition of an
inorganic acid to the urea melt, just before the prilling tower, in order to drastically
reduce the quantity of ammonia in the air from the prilling tower. The values
obtained are20-70 mg/Nm3. An interesting side-result of this method is that the
quantity of free ammonia in the prills is greatly reduced and there is a drastic
reduction in the presence of ammonia in the work environment(conveyor belt
chutes, storage). Of course the prilled urea contains about 2,000 ppm of relevant

35. 35
salt, with no detrimental effecton the use of urea as fertiliser and other industrial
uses.
FIGURE..15 PRILL TOWER
Bucket rotated with the help of motor. Due to centrifugal force, urea in liquid form
comes out of bucket through holes of surfaces. Natural Draft fan converts urea in
the solid form, during the air time (time of urea droplets in air) of urea granules

36. 36
.
FIGURE..16-UREA AT BOTTOM OF PRILL TOWER
• NEEM COATING OF UREA
The government of india decided that all urea produces in the india should be
neem coated
FIGURE..17-NEEM COATING

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• ADVANTAGES OF THE NEEM COATED UREA CAN BE
ENUMERATED AS FOLLOWS:
1. Saving of 10% of the losses of urea would amount to 2 million tons of urea or a
reduction in subsidy component to the tune of ` 1,700 crores per annum
(considering total subsidy on urea to be `18,000 crores per annum).
2. Proportional saving in the consumption of naphtha or natural gas.
3. Increased crop yields due to better nitrogen utilization.
4. Reduction in environmental pollution of ground water due to leaching of nitrates
and gaseous emissions.
5. Opportunity for entrepreneurs to commercialize local Neem Resources and
Development of Small Scale Industries in rural areas.
8. OXYGEN PLANT IN IFFCO AONLA :-
IFFCO is setting up a total of four oxygen plants in India at a cost of about
Rs 30 crore. Two plants will be established in Uttar Pradesh - at Aonla
in Baraily and the other one at Phulphur in Prayagraj. One each plant is
coming at Paradeep (Odisha) and Kalol (Gujarat).
Capacity of an oxygen plant :-
130 cubic metres per hour
project cost of oxygen plant:-
A plant that can supply 24 cylinders worth of gas per day costs about Rs 33 lakh to
set up and can be completed in a couple of weeks. A 240-bed hospital would require
about 550 LPM oxygen. A hospital of that size, say with 40 ICU beds, ordinarily uses
oxygen worth about Rs 5 lakh per month.

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OXYGEN PLANT
9. UREA PRODUCT QUALITY
 Controlling agency
• GOVERNMENT OF INDIA (GOI)
• THE FERTILISER CONTROL ORDER (FCO)

39. 39
 Safety Aspects
Safety is the state of being ''safe'', the condition of being protected Against physical
, social, financial , emotional ,physiological , educational Or other consequences of
failure, damage, error, accidents, harm or any Other events which can be non-
desirable. This can take the form of being Protected from the event or from exposure
to something that causes Health or economic losses. No industry can afford to
neglect the Fundamentals of safety in design and operation of its plant and
Machinery. It is important that all the people responsible for management and
operation of any industry should have a good knowledge of industrial safety.
 Accident factors
1 a personal accident injury occurs as a result of accident
2 an accident due to un safe act and/or unsafe condition
3 unsafe act/unsafe condition exists due to faults of persons
4 faults of persons due to negligence

40. 40
GY
 Safety Precaution
1. when taking sample of anhydrous ammonia and when operating or working
on ammonia valves, equipment containing ammonia such as ammonia feed pumps,
operators laboratory and maintenance personal must wear safety overalls.
2. goggles and rubber gloves. If any part of the skin has been exposed to
ammonia , wash immediately and thoroughly with water
3. work on the ammonia equipment should be done from the upwind side of the
equipment to avoid or minimize contact with escaping ammonia.
4. the location of fire hydrants, safety showers , eyewash fountains ammonia
canisters gas mask, emergency air breathing apparatus should be well known to all
person's
5. instruments containing mercury must not be used if ammonia is likely to come
in contact with mercury
 T List of safety equipment
A. respiratory protective equipment
1. self—contained breathing apparatus sets of 30 min and 10 min
2. continuous airline mask
3. trolley mounted self contained breathing apparatus set 2.5 hours
4. canister gas mask
5. dust mask/cloth mask (air purifying respirator)
B. non—respiratory protective equipments
1. helmets
2. ear muff and ear plugs
3. goggles
4. face shield
5. hand gloves
6. aprons

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7. safety shoes
8. suits
9. safety harness
C. warning Oinstrument
1. oxygen, carbon dioxide , chlorine, ammonia indicator with replaceable sensors.
2. explosive meters for measuring explosive range
3. fire fly instrument for confined space entry
D. Gas Leak Instruments
1.safety showers
2. manual water sprinklers
3. communication systems

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III. References
• Ammonia-2 Training Manual, IFFCO AONLA .
• Offsite Plants Training Manual, IFFCO AONLA .
• Power Plant Training Manual, IFFCO AONLA .
• Urea-2 Training Manual, IFFCO AONLA .
• Urea - Wikipedia, the free encyclopedia,
• http://en.wikipedia.org/wiki/Urea
• The Urea Technology, Snamprogetti Training Manual.