Gangaraju Project

Mini-Project Done

On

PRODUCTION OF AMMONIA, UREA AND CFG

MATERIAL BALANCE OF AMMONIA PROCESS

(Up to front head)

In

NAGARJUNA FERTILIZERS AND CHEMICALS LIMITED

KAKINADA

Submitted by:

KONA GANGA RAJU

Regd no :L10CH462, B.TECH 3rd year

CHEMICAL ENGINEERING

BAPATLA ENGINEERING COLLEGE, BAPATLA

Under the esteemed guidance of

Shri. P.CHANDRA MOHAN

Deputy General Manager (Technical Services).

NAGARJUNA FERTILIZERS AND CHEMICALS LIMITED

KAKINADA

ACKNOWLEDGEMENT

I wish to take this opportunity to express myself my deepest sense of

gratitude to my project guide Dr N.RAMGOPAL, HOD CHEMICAL ENGG

DEPT, for his able guidance and kind co-operation extended to me on

successfully bringing this project.

I would like to express my sincere gratitude to Shri. P. Chandra Mohan,

DGM (Technical services), Mr. M.P. Rama Rao (Training manager), for their

valuable guidance timely suggestions and encouragement given to me through

out the project work.

Last but not the least I thank one and all who have contributed their part in

helping me my Endeavour to accomplish the object of completing this project

work.

K.GANGA RAJU

CONTENTS

Chapter 1 COMPANY PROFILE

Chapter 2 AMMONIA PROCESS

Chapter3 MATERIAL BALANCE

Chapter 4 UREA PROCESS

Chapter 5 CFG PROCESS

Chapter 6 OFFSITES

Company profile Nagarjuna fertilizers and chemicals limited is a flagship company of the

Nagarjuna group. It is one of the leading manufacturer and supplier of plant

nutrients in India. NFCL is engaged in the manufacturing of urea fertilizer in the

complex located at Kakinada, A. P. It was founded by Sri KVK Raju, a visionary

man with the motto

“Serving society through industry”

He was a professional technocrat entrepreneur who realized the importance of

core section to an economy like ours. Thus was born Nagarjuna Group in 1973

with an investment of Rs. 50 million. The Group has since then come a long way

to become a diversified conglomerate with an asset base of Rs. 43 billion.

NFCL is the first gas based fertilizer industry in south India. The plant is

based on the latest fertilizer technology from SNAMPROGETTI; ITALY for UREA

manufacture and HALDOR TOPSOE PROCESS; DENMARK for AMMONIA

SYNTHESIS. The name plate capacity of ammonia plant is 990 tpd and that of urea

is 1500 tpd. The plants run successfully at high on-stream factor and capacity

utilization with low power consumption.

The feed stock for both UNIT – I and UNIT – II is Natural gas. Earlier

for UNIT – II fuel used to be Naptha, but now due to abundant availability of Natural

gas from the Krishna – Godavari basin, the unit has been switched over to Natural

gas. Also Fuel for entire complex is NATURAL GAS. The current consumption of

natural gas is around 1.8 million standard cubic meters per day. This gas is being

received through pipelines from TATIPAKA refinery marketed by GAIL and

Gadimagu refinery marketed by Reliance.

The construction of UNIT – I started in 1988 and the commercial production

commenced from AUGUST 1st 1992. The construction of UNIT – II started in 1995

and the commercial production commenced from MARCH 19th 1998. The factory is

located in a total area of 1130 acres of which 350 acres is occupied by plant and a

green belt of 780 acres.

Solutions

The potential benefits from improved plant nutrition are virtually limitless. With the

right plant nutrition it is not surprising that the grower can produce higher yields,

better flavored and greater nutritional content crops of vigor that are less prone to

pests and disease attack – goals which form the core of our plant nutrition

strategy. It is widely recognized by agronomists that plant nutrition is responsible

for approximately one-third of the increase in world grain production. The balance

is provided by such factors as better irrigation, improved seeds, cultivation

practices, pest control and planting density.

NFCL supplies a broad portfolio of nutrition products and services that include

both macro and micro fertilizers. It employs information technology and soil and

tissue analysis for nutrient recommendation and plans include further

strengthening of analysis portfolio with advanced tools to measure the actual

nutrient requirements and status and deliver customized nutrition solutions to meet the exact needs of the customer. It also provides knowledge-based

solutions to the vast farming community through information technology.

Micro Irrigation solutions are an effort towards facing perhaps the most serious

challenge of mankind in the 21st century - lack of fresh water. Its products and

services ensure slow, regular and precise delivery of water and agricultural

inputs to the crop.

NFCL offers expertise for taking over total responsibility of operation and

maintenance and other specialist services for the management of chemical

process plants.

NFCL operations and offerings have been aligned into Farming Solutions and

Nagarjuna Management Services.

Farming

Nagarjuna Fertilizers and Chemicals Limited is involved in the production and

marketing of a wide range of fertilizers. Urea, the widely used nitrogenous

fertilizer is both manufactured (at Kakinada Plant) and marketed through imports

(at Vizag and Kakinada Ports). In the vast Urea market, the brand “Nagarjuna” is

a highly regarded and preferred brand by the farming community. NFCL currently

markets about 1.4 million tons of Manufactured Urea and about 0.6 million tons

of Imported Urea per annum. With the aim of providing Total Solutions to the

farmers, NFCL has commenced marketing of fertilizer mixtures through domestic

sourcing and has further plans to enter into Phosphatic and Potassic segments

also.

The company also markets a wide range of micronutrients and micronutrient

mixes like Zinc Sulphate, Mahazinc, Muriate of potash, Di ammonium

phosphate etc. with emphasis on quality.

NFCL has associated with Haifa Chemicals Limited of Israel and Yara of Norway

to bring world class solutions to customers. It has been importing and marketing

water-soluble specialty fertilizers from Haifa Chemicals Limited (HCL), Israel,

since 1997. Haifa Chemicals is a global leader in the development, production

and marketing of specialty fertilizers offering a wide range of product lines to

match the specific needs of different farming programs.

ENVIRONMENTAL PROFILE

The company employees state of the art technology and designed to meet high

standards of energy conservation and pollutant discharge, lands.

a) Description of green belt:

In consonance with NFCL founder Mr. K. V. K. Raju’s philosophy, a vast

Green Belt has been developed over an area of 780 acres consist of 4,00,000 plants

with 170 species transforming the once highly saline marshy area devoid of any

vegetation into a lush green arboreal park. Green belt on the west of the factory is

formed by planting selected species of vegetarian of different heights, foliage and

other morphological features so as to constitute a thick green leaf wall between

factory site and township. Similarly the available land on the southern side and

various free spaces in the factory area is fully planted with vegetation of various

types of an environment congenial in all respects.

The ecological system created in and around the plant site

provides water bodies. Suitably located so that the total atmosphere is made

conductive to animals, birds, fish etc. Liquid effluent from the plant treated to

adequate levels of purity is utilized both for sustaining the vegetation and for

formation of the water bodies suitable for aqua culture.

A Deer park been developed in green belt which consists of

rabbits, peacocks, ducks and turtles etc. NFCL green belt has been accorded the

status of “mini zoo” by central zoo authorities. The evaluation of this ecological

system in the out come of efforts combined wisdom and extensive experience of

eminent experts in diverse disciplines such as forestry, horticulture, soil, chemistry,

ornithology land scarping animal and aquatic sciences. The NFCL’s green belt

development stands out as model for future industrial ventures in maintenance of

environment and development of ecology. The company is also maintaining a lawn

under the name of KVK Sunderavanam.

Significant environmental benefits of green belt

The Green Belt constitutes a thick green leaf wall full of life with flora and fauna

between factory site and Kakinada town. This acts as a safety measure, arresting

particulate matter physically and releasing O2. Green belt development stands out

as model for future industrial ventures in maintenance of environment and

development of ecology.

Carbon-di-oxide absorption

Oxygen release

Prevention of ground water evaporation

Sub soil erosion

Dust curtain

Barrier between factory and Kakinada town

Increasing soil fertility

Reduce the temperature through moisture

Ecological balance

Safety Services

Ammonia, Urea and Steam & Power plant operations are hugely hazardous by

nature. Safety professionals are key resources for working in close coordination

with plant personnel to ensure total safety of the plant and machinery and human

resources. This group also ensures meeting all statutory requirements. Safety

guidelines are prepared, standards are framed and compliance is monitored. Site

and Offsite emergency plans are prepared and issued. Emergency mock drills

are conducted for all-time preparedness. Fire fighting system is kept in full

readiness to fight any major or minor fire. The group imparts training and

retraining to all plant professionals, factory workers, office workers and contract

workmen. The group is credited with helping the NFCL plants achieve the 5-star

rating from British Safety Council.

Safety standards followed by the company are:

ISO – 9001 Quality Management System (QMS)

ISO – 14001 Environmental Management System (EMS)

ISO – 18001OHSAS – Occupational Health Safety And Associated Systems

PSMSProcess Safety Management System

EPPEmergency preparedness Plan

AMMONIA PROCESS

Natural gas supply

Desulphurisation section

Reforming section

CO conversion section

CO2 removal section

Methanation

Process condensate stripping section

Ammonia synthesis section

Refrigeration section

Ammonia absorption section

Purge gas recovery unit

The raw materials of this plant are AIR and NATURAL GAS. Natural gas

contains 0.2 ppm of sulfur. So, when Natural gas is used as feedstock its sulfur

contents must be reduced first. For this a unit called as pre-desulphurization unit

is used, where S is removed.

PRE-DESULPHURIZATION:

Natural gas contains sulfur compounds of types R-SH, R1-S-R, R-S-S-R1 etc and

many more. These compounds are removed by hydrogenation process where H2

is added. The reactions that take place inside the hydrogenator are:

R-SH + H2 R-H + H2S

R-S-R1 + 2H2 R-H + R1-H + H2S

R-S-S-R1 + 4H2 R-H + R1-H + 2H2S

CATALYST: NIMOX (NICKEL-MOLYBDENUM)

OPERATING CONDITIONS: 380OC, 24 KSC.

So, S is removed to a large extent as H2S and then sent to the final

desulphurization unit.

FINAL DESULPHURIZATION:

In this section the same process of HYDROGENATION is done. So the H2S

formed now is sent into the reactors where ZNO beds are present. The sulfur

removal inside the beds takes as follows:

ZNO + H2S ZNS + H2O

The process gas thus obtained is sent to the Reforming section.

REFORMING SECTION:

Reforming means conversion of hydrocarbons to CO2 with the help of steam.

This takes place at high temperatures since it is an endothermic reaction.

The reactions that take place are called as shift reactions.

CH4 + H2O CO + 3H2

CH4 + 2H20 CO2 + 4H2

CATALYST – Ni based catalyst.

TEMPERATURE - The temperature required is nearly 950oC.

Reaching this temperature at once is very difficult and thus it is done in 2

stages:

1. Primary Reforming

2. Secondary Reforming

PRIMARY REFORMER:

This reformer contains 190 tubes in 2 parallel sections and each section into 56

rows. The furnace operates with side firing of fuel gas on both sides of each row

of tubes. There are 360 side fired wall burners arranged in 6 rows and each row

having 15 burners. These tubes are filled with Ni catalyst. Super heated steam

along with natural gas is sent into small tubes. Nearly 86% conversion takes

place. Thus the product stream contains C0+C02+CH4+H20. This is sent to

secondary reformer.

SECONDARY REFORMER:

Product stream along with air is sent inside the reformer where it is heated to

945oC for the rest 14% conversion of CH4.

The product stream now contains only CO, CO2, H2 and AIR. In order to convert

CO to CO2 it is sent into the CONVERTER via WASTE HEAT BOILER. This

waste heat boiler recovers the heat from the product stream and is used for

rising temperature.

This section should be maintained at low pressures. Because high temperatures

and high pressures favors for unit operation called CRACKING which results in

the formation of CARBON. This carbon formation reduces the Ni catalyst

activity and so it is to be avoided.

HT CO CONVERTER:

From waste heat boiler the process gas enters High Temperature CO converter.

This is maintained at 380oC. Although CO conversion to CO2 takes place at low

temperatures this converter is used in order to increase the speed of reaction.

CATALYST: Cu promoted IRON OXIDE is used.

CO+H2O CO2+H2

LT CO CONVERTER:

The stream from HT CONVERTER enters the LT CONVERTER and the CO

formed in the process is converted to CO2. This is maintained at 140oC. The

product stream contains CO2, N2, H2, Ar and traces of CO.

CO+H2O CO2+H2

CO2 REMOVAL SECTION:

CO2 that is present is to be separated and thus it is sent into a tower where it is

made to mix with a solution called GV SOLUTION (GIMMARCO –

VETRACOKE SOLUTION) whose constituents are K2CO3, V2O5, DEA and

GLYCINE. V2O5 acts as the catalyst and DEA, GLYCINE are the initiators of

the reaction.

The operating conditions are 2.5 KSC, 250oC.

The reaction that takes place is:

K2CO3 + H20 + CO2 2KHCO3

CO2 REGENERATOR:

This KHCO3 is to be stripped for removing the CO2 from the GV SOLUTION.

This stripping is done both at high pressures and low pressures. High pressure

regeneration at 1 KSC is done where steam is made to flow counter-currently to

KHCO3 solution. This helps in CO2 stripping off. Traces of CO2 that are

present are also to be stripped and thus they are sent into the low pressure

regenerator. This regenerator is made to work at 0.1 KSC. This process gas is

now made to pass through the METHANATOR so that traces of CO2 left out is

converted into CH4 once again and this is called as “reverse shift reaction”.

CO2 + 4H2 CH4 + 2H20

NH3 SYNTHESIS SECTION:

N2 + 3H2 2NH3 – heat

1. The forward reaction can be favored by high temperatures and low

pressures.

2. The catalyst used is Fe based.

3. High Ar and CH4 concentrations reduce the partial pressure of N2

and H2. Hence the inert gas percentage must be not more than 8%.

4. H2/N2 ratio is maintained at 2.78:1.

The ammonia synthesis reactor consists of series of catalyst beds. The synthesis

gas enters the first bed at 252oC and when it comes out the temperature

increases to 530oC and as it goes to the second bed the temperature is again

brought back to 252oC with the help of exchangers. The pressure maintained is

145 KSC. Only 17% of NH3 is formed and the rest is recycled back.

PROCESS CONDITIONS:

Ammonia Synthesis reaction is affected by the following parameters:

Ammonia content in the feed gas

Inert gas content in the feed gas

H2 to N2 ratio in the feed gas

Reaction temperature

Circulation Rate

Operating pressure

Catalyst activity

REFRIGERATION SYSTEM :

NH3 formed is sent into series of chillers where the same compound acts as the

refrigerant. Thus liquid ammonia formed is separated out and the purge gas that

is sent is sent for recovery process where we can recover 90% of hydrogen.

PURGE GAS RECOVERY:

The purge gas contains traces of ammonia, hydrogen, CH4, Ar and this gas is

reduced to very low temperatures where ammonia separates out and still its

temperature is made to come down so that Ar and methane are also separated

and only H2 gas is left and it is recycled back to ammonia reactor.

MATERIAL

BALANCE OF

AMMONIA

PROCESS

(upto front head)Steam to carbon ratio entering the primary reformer

Composition of Natural Gas feed (dry basis)

Component

O2

N2

CO2

CH4

C2+

Mole%

0.13

1.24

0.11

96.98

1.54

Composition of Recycle Gas(dry basis)

Component

H2

N2

AR

CH4

Mole%

72.59

26.08

0.31

1.02

PROCESS STEAM

Considering Natural gas streamFlow of NG(dry basis) =26139/22.414= 1166.1908 kmoles/hr.Carbon no in NG stream

=(0.11+96.98+2*1.54)/100=1.0017.Amount of carbon in Natural gas

=1.0017*1166.1908 =1168.1733 kmolesConsidering Recycle gas streamFlow rate of gas stream

=1306/22.414=58.2672 kmoles.Carbon no in Recycle gas stream

=(1.02)/100=0.0102.Amount of carbon in Recycle gas

=0.0102*58.2672=0.5943 kmolesTotal amount of carbon entering

=1168.1733+0.5943=1168.7676 kmolesFlow rate of Steam =70327 kg/hrFlow rate of condensate =136 kg/hrAmount of steam entering F-201(reformer) =(70327+136)/18 kmoles/hr

=3914.6121 kmoles.

Ratio of steam to carbon entering F-201=3914.6121/1168.7676

=3.349

Material balance over primary reformer

Component

H2

N2

CO

CO2

CH4

C2+

Mole % in inlet stream

3.21

2.43

-----

0.11

92.77

1.47

Mole % in outlet stream

66.58

0.82

7.74

10.83

14.03

-----

NATURAL GAS FEED

RECYCLE GAS STREAM

PRE-HEATER& DESULPHURIZATION

UNITPRIMARY

REFORMER

CARBON BALANCE

Carbon no in inlet stream =(0.11+92.77+2*1.47)/100

=0.9582

Carbon no in oulet stream=(7.74+10.83+14.03)/100

=0.326

Amount of carbon entering F-201 =1168.7676 k moles

»Amount of dry gas entering F-201=1168.7676/0.9582=1219.7533 kmoles

Applying carbon balance

Inlet carbon content = outlet carbon content

1168.7676 = (amt of dry gas leaving)*0.326

»amount of dry gas leaving =3585.1767 kmoles

=80358.15 NM3/hr

HYDROGEN BALANCE

Hydrogen no in inlet stream =3.8632

Hydrogen no in outlet stream =1.8928

Amount of hydrogen entering F-201=1219.7533*3.8632

=4710.6872 kmoles.

Amount of steam entering F-201=3914.5177 kmoles.

Amount of hydrogen in steam =3914.5177*2

=7829.0354 kmoles.

Total amount of hydrogen entering F-201 =7829.0354+4710.6872

=12539.7226 kmoles.

Amount of hydrigen reacted =1.8928*3585.7676

=6787.1409 kmoles

Amount of unreacted hydrogen =12539.7226-6787.1409

=5752.5817 k moles

Amount of unreacted steam =2876.2908 kmoles.

Amount of process gas leaving F-201(including steam)=2876.2908+3585.7676

=6462.0584 kmoles

flow rate of outlet stream of F-201 =144840.6 NM3/hr

Material balance over secondary reformer(R-203)

Compositions of streams

Component

H2

N2

CO

CO2

CH4

Mole % in inlet stream (from primary reformer)

66.58

0.82

7.74

10.83

14.03

Mole % in outlet stream

55.36

23.76

12.09

7.91

0.6

CARBON BALANCE

Mole % of carbon entering through process air=0.03

Amount of carbon entering (process air)=(38665/22.414)*0.03/100

=0.5175 kmoles.

carbon no in inlet stream =0.326

Amount of carbon entering R-203(from F-201)=0.326*3585.1767

=1168.7676 kmoles

Total amount of carbon entering R-203=1168.7676+0.5175

=1169.2851 kmoles

carbon no in outlet stream=0.206

By applying carbon balance

1169.2851=(outlet dry gas)*0.206

Amount of process gas leaving R-203=1169.2851/0.206

=5676.1413 kmoles

Flow rate of outlet stream=127225.03NM3/hr.

HYDROGEN BALANCE

Hydrogen no in inlet stream =1.8928

Amount of hydrogen enteringR-203(dry gas)=1.8928*3585.1767

=6786.0225 kmoles

Amount of steam entering =2870.144 kmoles

Amount of hydrogen entering (steam) =5740.288 kmoles.

Total amount of hydrogen entering R-203 =12526.3105 kmoles

Amount of hydrogen reacted =1.1312*5676.1413

=6420.851 kmoles

Amount of unreacted hydrogen =12526.3105-6420.851

=6105.4595 kmoles

Amount of unreacted steam =3052.7298 kmoles

Total amount of outlet stream =8728.871 kmoles

Flow rate of outletstream =195648.9157NM3/hr

Material balance over high tempeature shift converter

Composition of streams across R-204

Component H2 N2

COCO2CH4Mole % in inlet stream55.36

23.7612.097.910.60Mole % inoutlet stream

59.1121.762.6815.640.55

CARBON BALANCE

Carbon no in inlet stream =0.206Carbon no in outlet stream =0.1887Amount of carbon entering R-204=0.206*5676.1413=1169.2851 kmolesApplying carbon balance

1169.2851=(outlet dry gas)*0.1887Amount of dry gas in outlet stream=6196.5294 kmolesFlow rate of dry gas stream =138889.01NM3/hr.HYDROGEN BALANCE

Hydrogen no in inlet stream =1.1312Hydrogen no in outlet stream =1.2042

Amount of hydrogen entering R-204(dry basis)=1.1312*5676.1413=6420.851 kmolesAmount of steam entering =3052.7298 kmolesAmount of hydrogen entering (steam) =6105.4596 kmolesTotal amount of hydrogen entering R-204=12526.3106 kmolesAmount of hydrogen reacted =1.2042*6196.5294

=7461.8607 kmolesAmount of unreacted hydrogen =5064.4499 kmolesAmount of unreacted steam =2532.225 kmolesTotal amount of outlet stream

=2532.225+6196.5294=8728.7544 kmoles

Material balance over low temperature shift converter

Composition of streams

ComponentH2N2COCO2CH4

Mole % in inlet stream59.1121.762.6815.640.55

Mole % in outlet stream60.0921.240.2217.660.54

CARBON BALANCE

Carbon no in inlet stream =0.1887

Carbon no in outlet stream =0.1842Amount of carbon entering R-205 =0.1887*6196.5294

=1169.2851 kmolesApplying carbon balance

1169.2851=(outlet dry gas)*0.1842Amount of dry gas flowing out of the converter=6347.9104 kmolesFlow rate of dry gas in outlet stream

=142282.0637 NM3/hrHYDROGEN BALANCE

Hydrogen no in inlet stream =1.2042Hydrogen no in outlet stream =1.2234

Amount of hydrogen entering R-205 (dry gas basis)=1.2042*6196.5294

=7461.8607 kmolesAmount of steam entering the reactor=2532.225 kmolesAmount of hydrogen in steam=5064.4499 kmolesTotal amount of hydrogen entering R-205=12523.3106 kmolesAmount of hydrogen reacted =1.2234*6347.9014

=7766.0226 kmolesAmount of unreacted hydrogen =4760.288 kmolesAmount of steam unreacted =2380.144 kmolesTotal amount of outlet stream

=2380.144+6347.9014=8728.0454 kmoles

Flow rate of outlet stream =195630.4096NM3/hr.

GIAMMARCO VETROCOKE SECTION

Considering CO2 balanceCO2 entering GV section= Co2 to urea plant+ CO2 to methanator0.1766*6347.9014=0.9850(dry gas flow to urea plant)+0.001(CO2 entering methanator)----(1)Considering H2 balanceH2 entering GV section=H2 entering urea plant+H2 entering Methanator0.6009*6347.9014=0.01*(dry gas flow to urea plant)+0.7292(H2 entering methantor)----(2)Solving (1)&(2) equationsWe get

Amount of dry gas entering Urea plant=1132.8162 kmoles

GIAMMARCO VETROCOKE

CO2 REMOVAL

LOW TEMP SHIFT CONVERT

CO2 TO UREA PLANT

METHANATOR

Amount of dry gas entering methantor=5215.4769 kmolesConsider CO2 to urea streamConditions of steam are0.6kg/cm2.g and 40˚CVapour pressure of water at temperature T is given by

ln P=A+B/T+ClnT+DT2------(2)Where pressure(p) is in Pascal and temperature(T) is in kelvin and

A=73.649B=-7258.2C=-7.3037D=0.00000417

vapour pressure of the water at above conditions=3094.0287 Pa

=0.0315kgf/cm2mole fraction of water=0.0315/0.6=0.052

wet flow rate of CO2 to urea stream=dryflow/(1-m.f)=1132.8162/(1-0.052)=1194.9538 kmoles=26783.69NM3/hr

similarly considering inlet flow to methanatorconditions pressure =25.9kgf/cm2.

temp=65˚C=338Kby above equation (2)vapour pressure of water at above conditions=24875.8486 Pa=0.2537kgf/cm2.

Mole fraction of water =0.2537/25.9=9.795*10-3

Wet flow of stream entering methanator=5215.8162/(1-9.795*10-3)

=5267.4124 kmoles=118063.7815 NM3/hr.

Material balance over methanator

Composition of stream entering methanatorComponent

H2N2CO

CO2CH4

Mole% 72.9225.760.270.100.64

CARBON BALANCE Carbon no inlet stream =0.0101Carbon no in oulet stream =0.0102Amount of carbon entering R-301=0.0101*5215.8162

=52.66797 kmolesApplying carbon balance

52.6797=(dry gas out flow )*0.0102Amount of carbon leaving R-301=5164.6807 kmoles.

HYDROGEN BALANCELow pressure steam entering GV solutions =2750 kg/hr=152.77 kg molesAmount of hydrogen in steam =305.55 kmolesAmount of unreacted steam entering R-301 =2380.144 kmolesAmount of hydrogen in unreacted steam =4760.288 kmolesTotal amount of hydrogen entering =12806.1092 kmolesAmount of hydrogen reacted =1.4926*5164.6807

=7708.802 kmolesAmount of unreacted hydrogen =12704.8152-7708.802

=5097.3072 kmolesAmount of unreacted steam =2548.65336 kmolesWet out flow rate of dry gas stream =5164.6807 kmoles

=115761.135 NM3/hr

AMMONIA REACTOR

Tie component is ArgonAmount of argon entering R-501=(2.14/100)*5164.6807=110.5242 kmolesExit argon mole %=2.41%

110.5242=(2.41/100)*(out flow gas)Exit dry gas out flow=4586.065 kmoles=102792.061 NM3/hr.Hydrogen(H2) conversion %Hydrogen entering reactor=65.92*5164.6807/100=3404.5575 kmoles.Amount of hydrogen leaving R-501=55.43*4586.065/100=2542.056 kmoles% of conversion=(inlet-outlet)/inlet=(3404.5575-2542.056)/3404.5575=25.33%Nitrogen(N2) conversion %Amount of nitrogen entering R-501=0.2198*5164.6807=1135.197 kmolesAmount of nitrogen leaving R-501=0.1847*4586.065=847.0462 kmoles% of conversion=(inlet-outlet)/inlet=(1135.197-847.0462)/1135.197=25.38%

The Urea production takes place through the following main

operations:

Urea Synthesis and High Pressure Recovery

Urea purification in the medium, low and pre-vacuum pressure

recoveries.

Urea concentration

Urea Prilling

Process Condensate Treatment

CO2 and NH3 obtained in ammonia plant are sent into UREA PLANT. Since the

reaction requires high pressures both the reactants are compressed.

1. NH3 being a liquid is compressed with the help of AMMONIA BOOSTER

PUMPS and the feed is pumped into the reactor with the help of

RECIPROCATING PUMPS. The reactant is compressed till it reaches 240 KSC.

2. CO2 is compressed with the help of compressors from 0.6 KSC to 159 KSC.

This is done with the help of a steam turbine driven 4-stage CENTRIFUGAL

COMPRESSOR SYSTEM.

3. CO2 is compressed to 6.5 KSC during the first stage and then to 21 KSC after

the second stage and to 91 KSC after the third stage and finally to 159 KSC. The

condensates are removed after each and every stage and this compressed CO 2 is

directly sent into the UREA REACTOR.

SYNTHESIS AND H. P. SECTION:

NH3 [240 KSC, 135oC] and CO2 [159 KSC, 105Oc] are sent inside the reactor. The

residence time is 22 minutes. The reacting conditions are 189oC and 157 KSC. The

reactions taking place are:

2NH3 + CO 2 NH2COONH4

NH2COONH4 NH2CONH2 + H2O

The outlet contains 33% urea. This product is sent into the stripper where NH3 acts

as the self-stripping reagent. Thus, NH3, CO2 and H2O are separated to some

extent. 43% concentration of urea is obtained.

CARBAMATE DECOMPOSITION TAKES PLACE AT LOW PRESSURES

AND OPTIMUM TEMPERATURES.

M.P.DECOMPOSITION & RECOVERY SECTION:

1. Urea [17 KSC, 155oC] is sent into the decomposer where the concentration

rises to 62% and the off gases (NH3, Carbamate) are sent into the condenser

where ammonia is separated and sent into ammonia storage tank. Carbamate

that is present is sent into the Carbamate solution tank for storage and

further usage.

2. This whole loop is maintained at 17 KSC and thus is called as medium

pressure loop and now it is sent into low pressure decomposer.

L. P. DECOMPOSITION:

1. Urea [4 KSC, 145oC] is sent into low pressure decomposer where 72% urea

is obtained. The gases that are formed are condensed and condensates are

removed and the remaining solution is sent to the Carbamate tank.

2. The urea is sent into PRE-VACUUM CONCENTRATE where the urea

concentration rises to 87%.

3. In this whole process water formed has to be removed and so it is sent into

vacuum section

VACUUM CONCENTRATION:

1. Two vacuum separators are present in which urea is pumped into the first

maintained at 0.35 KSC and 130oC.

2. This separator outlet is the input of the second one maintained at 0.035 KSC.

This fine pressure is obtained with the help of EJECTORS.

3. These 2 separators separate out water with urea and 99% concentration is

achieved.

4. This highly concentrated is maintained at 136oC because at high

temperatures BIURET FORMATION takes place.

5. Water obtained is condensed and then sent into waste water tank. It contains

5% Ammonia and 1% Urea. Molten urea is sent to the

PRILLING SECTION:

1. The height of the urea prilling tower is 100 meters and 22 meters in

diameter.

2. We have a bucket at the top of the tower rotating at speed of 250 RPM

which has holes in it. This molten urea is pumped to make it fall through the

bucket and air is supplied from the bottom of the tower. So the liquid falling

from the bucket gets cooled and thus small prills are formed. These are

collected on a rotary scrapper which is connected to a belt that is directed to

the BAGGING PLANT for bagging purpose.

PROCESS CONDENSATE TREATMENT:

Waste water from the tank is sent to the DISTILLATION COLUMN. STEAM is

provided from the bottom. Pure water obtained at the bottom end is sent to the DM

plant for further processing. Ammonia that is present escapes from the top of the

tower and it is cooled in a condenser and is then directed to the AMMONIA

STORAGE TANK. UREA is collected at the plate that is present at the middle of

the distillation column. This is sent into HYDROLYZER where HIGH

PRESSURE STEAM [37 KSC, 370Oc] is pumped in. Because of high pressures

Urea decomposes into NH3 and

CO2. CO2 escapes out into atmosphere and NH3 is again condensed and sent back

into storage tank.

UREA PRILLS SPECIFICATION:

COMPONENT CONCENTRATION

Nitrogen 46% minimum by weight

Biuret 1% maximum by weight

Moisture Content 0-3% maximum by weight

Sizing 90% [2 – 4 mm size]

CFG PROCESSDESCRIPTION OF PROCESS PLANT

BRIEF DESCRIPTION OF THE PROCESS:The solid raw materials like DAP. MOP, Urea, Filler compounds like

Dolomite , clay etc and Micronutrients like Boron, Sulphur etc are

proportioned (weighed) and premixed in a paddle mixer and fed to

granulation drum (a rotary drum unit )where agglomeration is initiated.

In the granulator steam and/or water is added to provide sufficient

liquid phase and plasticity to cause the dry raw materials to

agglomerate further into product-size granules. The moist and plastic

granules are dried, in a rotary drum-type, Natural gas -fired dryer and

screened to remove the product-size fraction. Cooling is performed in

a rotary drum-type unit that is very similar to the rotary dryer. The

oversize material is crushed and recycled to the granulator along with

the undersize fraction. The product size fraction is passed through a

coating drum where it is coated with anti caking agent and

micronutrients like Zinc is added to the fertilizer and then is sent for

bagging. The process flow diagram is shown in Annexure III. The

process air from various equipment of the plant is taken to de-dusting

and water scrubbing system and after thorough cleaning it is vented to

atmosphere through stack. The scrubbed liquor is recycled to the

granulator.

DETAILED DESCRIPTION OF THE PROCESS:

The plant can be divided into the following sections

a. Raw material receiving section

b. Raw material feed section

c. Granulation and the main process section

d. Finished product Coating and bagging section

e. Pollution control section.

CUSTOMISED FERTILIZER PROCESS FLOW (TYPICAL)

PROCESS DESCRIPTION

Raw material section:

The different raw materials, namely, Urea, DAP, MOP, Filler etc

received in bulk or in bagged form, are stored Raw Material Storage

area accessible for front pay loader loading or manual feeding.

UREA, 1.08 MT/ hr

DAP, 13.91 MT/ hr

MOP, 2.67 MT/ hr

DOLOMITE, 2.36 MT/ hr+CONDITIONER + Micro nutrients(Sulphur,Boron etc.) RAW MATERIAL HOPPERS

WEIGH FEEDERS

GRANULATOR

DRYER

SCREEN

COOLER

COATING DRUM

PRODUCT BAGGING

STEAM (satd) 1.20 MT/ hr@ 3.5 bar

HOT AIR GEN

AIR

NG 280 Sm3/ hr@ 6-45 bar

WATER @ 4 Bar 1.5 MT/ hr

SCRUBBER LIQUOR 5 m3 / week Recycle to Granulator/PURGE (TO GREEN BELT after treatment)

DEDUSTING AND SCRUBBING

SECTION (WITH CYCLONES,

SCRUBBERS, CIRCULATION,

PUMPS & STACK)

BAGGED 20 MT/ hr

CF PRODUCT

RECYCLE

OVERSIZE CRUSHER

Micronutrients (Zinc)

Micro-nutrients, coating agent, required would be handled and

stored separately in the Raw Material Storage area.

Raw material feed section:

The different raw materials are fed into respective feed hoppers(3

Nos. each 5MT Capacity) using front pay loader or by manual

feeding. The materials are then transferred to the Raw material feed

elevators (3 nos.) through Raw Material feed conveyors (3 Nos). The

material from the elevators top is fed into different hoppers (6Nos.

of capacity 30MT each). Depending on the product blend, these

hoppers are loaded for several hours of operation requirement. From

the hoppers the material is fed at the specified rate through Weigh

feeders (6Nos) to the crushers (2Nos.) through Mixed Raw Material

Conveyor. Crushers out let material is fed to the paddle mixer. The

Paddle Mixer outlet material is fed to Granulator feed elevator

through Mixer Discharge belt conveyor. The granulator feed elevator

lifts this entire material to the Granulator floor for further processing.

A stacker is provided to lift Micronutrient bags to the Micronutrient

hopper floor to feed the hoppers(4 Nos. 1MT capacity each)

manually. Depending on the product blend, these hoppers are

loaded for several hours of operation requirement. From the hoppers

the material is fed at the specified rate through Weigh feeders

(4Nos) to the Paddle mixer through Mixed Raw Material Conveyor.

The Paddle Mixer outlet material is fed to Granulator feed elevator

through Mixer Discharge beltconveyor.

Granulation and main process section:

The material at the out let of Mixer Discharge belt conveyor is fed to

the granulator through a Bucket elevator named Granulator feed

elevator.

The granulator is a rotating drum( 2.2meter Dia,7.5 Meter long)

designed to increase the size of the incoming seed by adding layers

during the rolling motion. In this process densification and roundness

of the granule are achieved. Sparger pipes are located in the

granulator for spraying Water/Steam and Scrubber liquid (From the

Scrubber liquor sump) onto the bed of material.

From the granulator the material having approximately 10%

Moisture is dropped to the rotary dryer. The dryer is a rotating drum(

2.2meter Dia,16 Meter long), where the moisture is evaporated from

the material through heat transfer with co-current hot air flow. A

natural gas fired furnace is used for generating hot air of 10,000

M3/Hr. of air upto 250 Deg C . Flights are used in the dryer for lifting

the material, for achieving better heat transfer. The product

moisture content is usually reduced to a target of 1% exit dryer.

The material from the dryer falls on the transfer belt conveyor to

which feeds the material onto a rotary cooler. The cooler is also a

rotating drum similar to dryer ( 2.2meter Dia,12 Meter long). The

flights allow for proficient cooling of the product with the ambient

air. The outlet product temperature depends on the conditions of the

air used for cooling.

The cooler outlet material is fed to the screen feed elevator which

feeds material to the Rotary screen ( 1.0 meter Dia,4.0 Meter long).

Here the fines and over size are separated .The fines are fed to the

paddle mixer through recycle conveyor. The over size material is

crushed in crusher and is put to recycle conveyor.

Finished product coating and bagging section:

The on size product from the rotary screen is fed into a coating

drum, where the finished product is coated with anticaking agent for

avoiding cake formation through spray system. Anti caking agent is

stored in a tank under constant electric heating and is pumped to

the spray nozzle fitted in side the coating drum. The product after

getting coated with anti caking agent is sprayed with micronutrient

like Zinc sulphate powder through weigh feeder located below

Micronutrient storage bin of 1.0 MT capacity. The product then,

through a product conveyor is fed to bucket elevator which in tern

feeds product bins (2Nos.30MT each) directly. The product is bagged

in 50Kg bags by automatic Weighing and bagging machines (2Nos.

500 Bags/Hr each) and stitching machines (2Nos) is then dispatched

either through rail or road.

Pollution control section:

The plant contains stack and pollution control equipments for

guarding the environment and to avoid material loss.

The dryer air(25,000M3/Hr) and the cooler air (25,000M3/Hr) are

taken to dedicated dust scrubbers(316 SS) through dedicated

cyclones for removal of dust and after scrubbing it with circulating

water in scrubber, the dust free air is sent to stack (30 Meter Hight).

All the collected dusts are recycled back in the process. The

Scrubber liquor is fed to granulator .

Instrumentation and control:

A CCS (Centralized Control System) takes care of the overall control

of the plant and the product mix. In specific, Weigh feeders will

ensure precise measurement and supply of raw materials

/Micronutrients from the hoppers to the paddle mixer , which is

considered critical for the quality of the finished product.

Temperature indicator for furnace air and Natural gas burner control

systems are provided for process control.

RAW MATERIALS AND UTILITIES

Raw Materials & their availability:

The Customized Fertilizers plant is being located at Kakinada,

in Andhra Pradesh. Depending upon the formulation and the

process needs specific raw materials are required.

It is envisaged that currently only subsidized raw materials like Urea,

DAP and MOP along with filler materials and micronutrient would be

used. The requirement of Urea shall be met from in-house

production of Nagarjuna Fertilizers and Chemicals Ltd. For DAP, it can

be sourced from Indian manufacturers like Paradeep Phosphates Ltd,

Iffco etc, or can be imported or Godavari Fertilizers Ltd which is next

door can be one of the options. MOP will be sourced from IPL or can be

imported.

To have a cost effective and reliable source of raw materials, it is

proposed to have Long term purchase agreement with companies in

India and abroad.

Raw Materials - Quantities:

The quantities of various raw materials required in the

production of 1.30 lakhs MTPY of Customized Fertilizers are

variable depending on the grades we produce .

Raw Material Consumption

Typical quantities of raw materials comprising of Urea, DAP ,MOP and with or without micronutrients* to manufacture Customized Fertilizer

Input Hourly rate Output Hourly rate1. Urea 1.08 MT - -2. DAP 13.91 MT - -3. MOP (KCl) 2.66 MT - -4. Dolomite 2.36 MT - -5. - - Product CF 20.0 MT_________________________________________________________

Total 20.0MT 20.0 MT

* Zinc,Boron,Magnesium,Iron,Copper etc.

Utilities &Packing materials Consumption

• Raw Water : 35 M3/Day

• Low Pressure Steam : 30MT/Day

• Power : 25KWH/MT

• Natural Gas : 7400SM3/Day

• Packing material :8000 Nos.of 50 Kg Empty HDPE Bags

BAGGING PLANT

Bagging means pre-weighing UREA in a machine, dumping the pre-

weighed urea material into a bag and stitching the bag.

NFCL has 8 bagging streams. Each stream having a

Bunker

Electronic bagging machine

Wooden slat conveyor

Stitching machine

Urea coming from the urea plant via conveyor belt is dumped into

bunkers. From this urea is weighed 50 Kgs by a weighing machine and with the help of

electronic bagging machine this is dumped into bags and the stitching is done. These

packed beds via conveyor belts are sent for lorry and wagon loading

.

UREA GRANULE SPECIFICATION:

COMPONENT CONCENTRATION

Nitrogen 46% minimum by weight

Biuret 1% maximum by weight

Moisture Content 0-3% maximum by weight

Sizing 90% [2 – 4 mm size]

POWER PLANT

The total power requirement to the plant is 32-33 MW.25MW

power is obtained from the gas turbines. The rest is obtained from the power Grid.

The instrument air is sent into the air compressor where it is compressed to a certain

pressure and is made to flow into the combustion chamber. Here it is mixed with fuel

(Natural Gas) which is injected by fuel nozzles. The burning fuel will raise the

temperature without changing in pressure. The hot gases expand in the turbine through

which the rotation of turbines is made.

This mechanical energy is converted to electrical energy with the

help of generator and this electricity produced is used for running the plant. The flue

gases are left into air with the help of stacks. The recovered heat is used for further

heating of natural gas that is supplied to the combustion chamber. There are three gas

turbines which satisfy most of power requirements of the plant. The three gas turbines

are:

Turbine Power Generated

I. GT-A 7.5 MW

II. GT-B 7.5 MW

III. GT-C 17.5 MW

PRE-TREATMENT PLANT

Raw water from samalkot reservoir is stored in raw water storage tank.

This water which consists of mud and micro-organisms are to be removed. For this

process the raw water is sent to the STILLING CHAMBER where CHLORINE is added.

This chemical is helpful for killing bacteria and the mud that is present is settled in the

stilling chamber. Then raw water free of micro-organisms now contains suspended

particles and colloidal particles. This is now treated with coagulation agent ALUM

(chemical formula – Al2(SO4)3.18H20). What alums do is that they collect all the

suspended particles as a particular mass and then they help in separating them out.

This helps in separation of finely suspended matter. This water is now sent into

CLARIFLOCCULATOR, which is a circular tank with flocculation zone in the centre and

outer being the clarifying zone for sedimentation. Raw water entering the clariflocculator

discharges at the top of the flocculation zone through central opening provided in the

central shaft. Water entering the flocculation zone is subjected to slow agitation by

paddles that are provided. Thus, pure water obtained is now passed through the filter

beds to remove the residual suspended impurities from clarified water. The media

contains sand and gravel of desired quality. The water still containing residual

suspended matter passes down the filter during which solids are retained on the filter

media. This water is now sent to the DM plant for further purification.

DM PLANT

Water from PRE-TREATMENT PLANT is firstly sent into the

FILTER ACTIVATED CARBONS which helps in removal of TURBIDITY, CHLORINE

etc. This is now sent into a STRONG CATION EXCHANGER which is 4 in number. In

this exchanger ions of sodium, magnesium, aluminum etc are removed as mineral

acids. Then it is sent to DEGASSING TOWER. In this tower the water is made to fall in

the tower from the top and then air is sent from the bottom. This helps in removal of

carbon-di-oxide and hydrogen and other dissolved gases inside the water. Then it is

stored in the tower. Then it is now sent to the WEAK ANION EXCHANGER where weak

anions are removed and then directed into the STRONG ANION EXCHANGER where

the rest strong anions are removed. This water which might have traces of minerals (like

Si) is separated when it is passes through MIXED BED DE-MINERALIZER. Thus, pure

water obtained is free of minerals is sent into process plants and boilers for usage.

PROCESS CONDENSTE TREATMENT:

The water from the process condensate comes to the DM plant for further

processing. It is first sent into the FILETR ACTIVATED CARBONS and then through

MBDM (MIXED BED DE-MINERALIZER). This water is also sent to storage tank and for

further processing.

TURBINE CONDENSATES:

The water that is obtained as the turbine condensates are also processed

here. That is first sent into FILTER ACTIVATED CARBON and then to MBDM (MIXED

BED DE-MINERALIZER) and then to MBGT (MIXED BED GUARD TOWER). This

guard tower is used for removal of traces of minerals that are present inside the water.

This water is also sent for usage to boiler section or process plants.

EFFLUENT TREATMENT PLANT

This involves the removal of oil, sludge and Ph correction.

First of all oil bearing effluent from the process plant is collected in

the oil separation pit which has a disc oil separator supported by 3 floats which are

firmly secured to the two siding grids provided in the pit. The principle is based on the

adhesion of oil to the lateral surface of metallic discs arranged perpendicular and

partially submerged and rotating with respect to horizontal axis.

For this ammonia and urea bearing effluents, HCl is added to bring down

the Ph range from 7 to 8. When Ph of the mixed effluent is stabilized, it is pumped to

equalization pond by effluent recirculation transfer pump.

INERT GAS PLANT

This plant is designed to produce gaseous and liquid nitrogen with

a high level of purity. Process involves separation of air into nitrogen and waste gas rich

in oxygen. The air first is sent into the main air compressor where it is compressed to

high pressures and then sent into chillers where the temperature is decreased from

49oC to 12oC there by removing the bulk of moisture content. It is then sent into

molecular sieve bed which absorbs contaminants like CO2, hydrocarbons etc. Then the

pure N2 is then fed into the cold box where it is sent into expander and then the liquid

nitrogen is stored in storage tanks.

This nitrogen is used for purging inside the pipelines.

AUXILIARY BOILERS

Water from DM plant enters the de-aerator (mechanical and chemical),

where CO2, O2 etc are separated out. Then this is sent into the economizer where it is

pre-heated to certain extent. This preheated water is then sent into water drum which is

present at the bottom of the furnace. Now air here is forced by a fan into the gas air

heater where it is heated to very high temperatures and then it is sent into the furnace.

We have a steam drum present at the top of the furnace. Now as the preheated air is

supplied to the furnace the water gets heated up and becomes steam and as the

density decreases the water rises from the bottom to the top i.e. from water drum to the

steam drum. This air after it heats the water now is sent outside as the flue gas but as

its temperature is as high as 500oC it is made to pass through gas air heater where the

heat is recovered. After the heat being regained at the gas air heater it is sent outside

via stack which works on the principle of natural draught. The steam formed in the

steam drum is sent into the primary super heater and then to attemptator and then it is

sent into secondary super heater. Attemptator is used for maintaining constant

temperature. The super heated steam is sent for various purposes inside the plant.

COOLING TOWERS

Cooling towers are the towers which work on the principle of the OPEN

RE-CIRCULATING SYSTEM. Hot water from the pumps is re-circulated via heat

exchangers where it picks up the heat on the cooling towers and it is made to fall from

the top of the cooling towers where the water is cooled by evaporation. Thus the heated

water gets cooled in cooling towers with the mechanical draft (exhaust fan) provided at

the top of the tower.

CONCLUSION

I got acquainted with how Ammonia and Urea are prepared and various operations

carried out for their preparation at NFCL

Also learnt the functioning of different types of equipments both minor and major and

the way they are integrated into Ammonia and Urea plants.

I also had a chance for the practical application of my knowledge regarding the

subjects. .

At last staying with the well experienced company officials has been a rewarding and

motivation for me to design my career.