Hariom Report

Birla Institute of Technology & Science, Pilani. 1

A

REPORT ON

TO CARRY OUT THE ENERGY BALANCE OF UREA PLANT

&

SIMULATION OF MEDIUM PRESSURE ABSORBER(C-01)

BY

Name of the Student ID No. Discipline

Hariom Sharma 2009H101015P M.E Chemical Engineering

Prepared in Partial Fulfillment of the

Practice School-II Course No. BITS G639

AT

TATA CHEMICALS LIMITED, BABRALA

A Practice School-II Station of

BIRLA INSTITUTE OF TECHNOLOGY & SCIENCE, PILANI

(June, 2011)


BIRLA INSTITUTE OF TECHNOLOGY & SCIENCE,

PILANI (RAJASTHAN)

Practice School Division

Station: Tata chemicals Limited Centre: Babrala

Duration: From: 06 Jan. 2011 To: 18 June 2010.

Date of Submission: 13 June 2011

Title of the Project: To Carry out the energy balance of Urea plant & Simulation of

Medium Pressure (MP) Absorber (C-01) in an Urea Plant.

ID No.: Name of Student: Discipline:

2009H101015P Hariom Sharma M.E. Chemical Engineering

Name of Expert: Mr U.P .SINGH Designation: Manager-Urea Plant

Name of the PS Faculty: Prof. R. K. Tiwary

Key Words: Study,Analysis,Calculation,Simulation,Aspen

Project Areas: Designe

Abstract: The first part of the report looks at one of the problem which was assigned to me.

During the course of this assignment I done the energy balance of all section of Urea Plant.

The second part of report deals with the simulation of Medium Pressure Absorber(C-01) of

urea plant in aspen plus ,commercial process simulation software.The detailed results and the

curves can be accessed by running the simulation files which are attached with the soft copy

of this report.

Signature of Student Signature of PS Faculty

Date: Date:


BIRLA INSTITUTE OF TECHNOLOGY AND SCIENCE

PILANI (RAJASTHAN)

PRACTICE SCHOOL DIVISION

Response Option Sheet

Station: Tata Chemicals Ltd. Center: Babrala

ID No: 2009H101015P Name: Hariom Sharma

Title of the Project: To Carry out the energy balance of Urea plant & Simulation of

Medium Pressure (MP) Absorber (C-01) in an Urea Plant.

Usefulness of the project to the on-campus courses of study in various disciplines. Project should

be scrutinized keeping in view the following response options. Write Course No. and Course

Name against the option under which the project comes.

Refer Bulletin for course no and course name.

Code No. Response Option Course No. & Name

1 A new course can be designed out of this project.

2 The project can help modification of the course

content of some of the existing courses.

Process Plant Simulation

(CHE G541).

3 The project can be used directly in some of the

existing Compulsory Discipline Courses (CDC)/

Discipline Courses Other than Compulsory

(DCOC)/ Emerging Area (EA) etc. courses

Advanced Separation

Processes (CHE G615).

4 The project can be used in preparatory courses

like Analysis and Application Oriented Courses

(AAOC)/ Engineering Science (ES)/ Technical

Art (TA) and Core courses.

5 This project cannot come under any of the above

mentioned options as it relates to the professional

work of the host organization.

Signature of student Signature of Faculty

Date: Date:


ABSTRACT

The first part of the report looks at one of the problem which was assigned to me.

During the course of this assignment I done the energy balance of all section of Urea Plant.

The second part of report deals with the simulation of Medium Pressure Absorber(C-01) of

urea plant in aspen plus ,commercial process simulation software.The detailed results and the

curves can be accessed by running the simulation files which are attached with the soft copy

of this report.

Signature of Student Signature of PS Faculty

Signature of Guide Signature of General Manager

Date:

Place:


ACKNOWLEDGEMENTS

I would like to thank my mentor Mr. U.P. Singh for guiding me all through my project. I am

overwhelmed in all humbleness and gratefulness to acknowledge my debt to Mr. Azaz Ali,

Mr.Avineesh, Mr. Sanjay Kumar, Mr. Siva Prasad, Mr. Kamakhya and Mr. Adarsh for their

support and timely help. A special thanks to Captain K. Santosh, Mr. Rajendra Singh and Mr.

Thomas Varghese for taking care of us at TATA Chemicals Ltd. I would also like to thank Mr.

C. K. S. Raman and Mr. Mahenderpal for providing us freedom to refer books and avail the

software facilities in the Technical Library and Documentation Centre.

I am also indebted to BITS, Pilani for providing me the opportunity in the form of practice

school to enrich my practical knowledge. And of course, this project would never have been

complete without the immense motivation by our PS Faculty Mr. R. K. Tiwary.

Last but not the least; I would like to thank my parents for their blessings.

Hariom Sharma

2009H101015P


INDEX

Abstract

i

Acknowledgement ii

Index iii

List of Tables v

List of Figures v

Name Page Number

1. Introduction 1

1.1) Introduction to Tata Chemicals Limited, Babrala 1

1.2) Credentials of Tata Chemicals Limited, Babrala. 2

1.3) TCL Babrala: The Nation‘s Conceit 3

1.4) Milestones of Tata Chemicals Limited, Babrala 3

1.5) Composition of Tata Chemicals Limited, Babrala 4

1.6) Salient Features of Tata Chemicals Limited, Babrala 6

2. Fire and Safety 8

2.1) Fire Chemistry 8

2.2) Fire Prevention 8

2.3) Classification of Fires 9

2.4) Fire fighting Gadgets and Appliances 10

2.5) Safety Programme at T.C.L 11

2.6) Safety Provisions 11


3. Brief Introduction of Urea Plant 12

3.1) Raw Material Required for Urea Production 12

3.2) Manufacturing Procedure 14

3.3) Steam and Condensate Steam 18

3.4) Flushing Network 20

4. Project 21

4.1) To Carry Out The Energy Balance of Urea Plant 21

4.2) Simulation of Medium Pressure Absorber (C-01) 30

5. Conclusions and Recommendations 59

6. References 61


1. INTRODUCTION

1.1) INTRODUCTION TO TATA CHEMICALS LIMITED BABRALA

Tata Group, India's foremost business conglomerate. Tata Chemicals, by itself, is one of the

largest inorganic complexes in the world beginning to TATA Group. Its first plant, which is also

called inaugurated establishment of TATA. It is India's leading manufacturer and marketer of

inorganic chemicals and fertilizers, with a turnover of over Rs. 4000 crores and is part of the Rs

65,000-crore ($14.25 billion) TCL's products and production processes are benchmarked with

the best of global touchstones, and meet the most rigorous international specifications.,

Established in 1939. An ISO-9001/14001 OHSAS 18001 certified company, TCL has a varied

user industry base comprising glass, paper, textiles, food additives, petroleum, refining,

chemicals, dyes, pesticides, direct farm application etc. The products go into numerous end-use

applications in a variety of industries: glass, detergents, paper, textiles, agriculture, photography,

pharmaceuticals, food, tanning, rayon, pulp, paints, building and construction, and chemicals.

Tata Chemicals is also one of India's leading manufacturers of urea and phosphatic fertilizers.

With an export presence in South and Southeast Asia, the Middle East and Africa, it has set itself

the objective of achieving global cost competitiveness in soda-ash. Its foray into phosphatic

fertilizers follows the merger of Hind Lever Chemicals Limited into Tata Chemicals Limited.

TCL's phosphatic fertilizer complex at Haldia in West Bengal is currently the only

manufacturing unit for DAP/NPK complexes in West Bengal. The Haldia plant has production

volumes exceeding 1.2 million tones per annum. Tata Chemicals makes urea at its fertilizer

complex in Babrala. The complex has an installed capacity of 13, 14,000 metric tones per year,

which constitutes nearly 12 per cent of the total urea produced by India's private sector. Tata

Chemicals is among the world's largest producers of synthetic soda ash, with the largest domestic

market share, produced at the company's integrated complex at Mithapur on the Gujarat coast in

western India.

The fertilizers, sold under the brand name 'Paras', lead the market in West Bengal, Bihar and

Jharkhand. TCL is also a pioneer and market leader in the branded, iodized salt segment. Its salt

has a purity percentage of 99.8 per cent, the highest in the country.


1.2) CREDENTIALS OF TATA CHEMICALS LIMITED BABRALA

AWARDS:

Prestigious Industry Award, Govt. of UP., 1995.

National Energy Conservation Award, Ministry of Power, 1997.

National Energy Conservation Award, Ministry of Power, 1998.

Best Production Performance Award for Nitrogenous Fertilizers, Fertilizers Association of

India.

Second best productivity performance in Nitrogenous Fertilizers Industry, 1997-98.

Yogyata Praman Patra Award, 1998.

Jawaharlal Nehru memorial National Award for Pollution Control and Energy Conservation,

2000-01.

Golden Peacock Environmental Management Award, World Environment Foundation, 2001-

02.

Best Technical Innovation Award, Fertilizer Association of India, Dec.2004.

Excellence in Safety, Fertilizer Association of India, Dec.2—4.

Commendation Certificate for Strong Commitment to TQM, CII-Exim Bank Award for

Business Excellence, Nov.2004.

5 Star Rating in Safety, British Safety Council, UK, Safety Gold Awards, Greentech

Foundation, Delhi.

Indian Chemical Council (ICC) confers the ICC award for social responsibility 2005-06.

NSCI safety award for 2006.

ICC Aditya Birla Award for Best Responsible Care Committed Company and ICC Award for

Social Responsibility for 2005-06.

Fertilizers Association of India Award for the Best Technical Innovation 2007.

Nine ABCI (Association of Business Communicators of India) Awards, 2008.


1.3) TCL BABRALA: THE NATION’S CONCEIT

Substituting a part of the imports of Urea, TCL, Babrala is estimated to save the country

about Rs. 500 crores in foreign exchange every year and provide the farmer with

nitrogenous nutrient, which could help raise the food production about 4 million tones/year.

First major steps towards the fulfillment of a long standing TATA CHEMICALS

commitment to provide the farmer with an optimal package of agriculture inputs to safe

guard the food security of the company.

Produced more than 100% of the designated production during the first year of commercial

production.

Produced more than 8, 40,102.35 tons of Urea achieving a capacity of 113% in the

year1995-96, and produced 9, 51,764 tones of Nitrogenous Urea in year 1996-97.

Now produce capacity of 13, 14,000 metric tons of Urea per year, which constitutes nearly

12 per cent of the total urea produced by India's private sector.

Total production of urea at Babrala is 3300 tons/day maximum and 2600 tons/day average.

Current maximum capacity is 146%.

The Babrala facility, among the best of its kind in India and comparable to the best in the

world, has set new standards in technology, energy conservation, productivity and safety

It is the only fertilizer plant in the country to use dual feedstock: natural gas or naphtha, or a

combination of both.


1.4) MILESTONES OF TATA CHEMICALS LIMITED, BABRALA

Commercial Production Started on December 21, 1994

AMMONIA UNIT

First firing of Reformer Furnace for dry out of refractory October 12, 1994

First feed into Primary Reformer October 20, 1994

First Carbon Dioxide for making Urea October 23, 1994

First Ammonia production November 14, 1994

UREA UNIT

Urea Prill Test conducted October 04, 1994

First Prill Test conducted through Unit 2 November 05, 1994

Second Prill Test conducted through Unit 2 December 09, 1994

ISO 14001 certificates obtained in October 2000.

ISO 14001 certificate for Babrala township obtained in 2004.


1.5) COMPOSITION OF TATA CHEMICALS LIMITED, BABRALA

1. AMMONIA PLANT

Capacity: 2000 MTPD

Technology: HALDOR TOPSE Process, DENMARK

Plant (Single Stream) Production: 2000 tons/ day of liquid Ammonia.

Plant at TCL, Babrala is the first low energy plant in the country.

Basic scheme involves the following steps:

Desulphurization.

Primary and Secondary Reforming.

Carbon Dioxide Shift.

Methanation.

Synthesis and Chilling.

Storage and supply to Urea unit


2.UREA PLANT

Capacity: 2 X 1750 MTPD

Technology: SNAMPROGETTI Process, ITALY

Carbon Dioxide requirements supplied from ammonia plant.

Two urea strings have a common Prilling section.

Maximum Urea production: 3600 tons per day

Basic scheme involves the following steps:

Urea Synthesis

Waste Water Treatment section

3.OFFSITE AND UTILITIES

S. N. UNIT CAPACITY TECHNOLOGY

1. Ammonia Storage Tank 2X5000 MT M/S Kaveri Engineering

2. Captive Power Plant 1X110 TPH THERMAX/ L&T

3. Cooling Tower 24000 M3/hr M/S Paharpur Cooling Tower

4. D. M. Water Plant 3X450 M3

TCL, Mithapur

5. Gas Turbine Generator 2X20 MW THOMASSON, Holland

6. Heat Recovery Unit 2X90 TPH L&T

7. Naptha Bulk Storage

Tank

3X6300 KL M/S Technofab Engg. Ltd.


1.6) SALIENT FEATURES OF TATA CHEMICALS LIMITED, BABRALA

Location Babrala, District Badaun, Rajpura block, Gunnor Tehsil, Uttar Pradesh.

Approx. 160km. south-east of Delhi.

Land Area 1519 acres

Plant area:1,069 acres

Township area:350 acres

Green belt: 100 acres

Fuel Natural gas (main)

Naphtha (alternate)

Fuel Source Natural gas supplied by GAIL (HBJ Pipeline)

Naphtha from IOCL, Mathura

Consumptive water

source

Six deep bore wells.

Present installed

capacity

Ammonia:2000 MTPD

Urea: 3500 MTPD

Project cost 1532 crores

Man power

Deployment (During

Commissioning/

Erecting phase

Total 7,855,128 man-hours.

Peak (month) 405,799 man-hours.

Beneficiary states U.P., Bihar, West Bengal, Punjab, M.P., Assam.


UNIQUE FEATURES OF TATA CHEMICALS LIMITED, BABRALA

An integrated energy network, which is the key, factor in achieving high energy efficiency.

The flexible range of the ratio of natural gas and naphtha as a fuel/ feed is a major reason

for this. The current low operating energy record is 5.055 Gcal/T of Urea.

The second unique feature is common single central control room (CCR) for ammonia,

Urea to captive power and steam generation plant (CPSSGP) and other offsite and utility

plants. This provides a well coordinated and integrated control of the entire complex from

one location and on line inters plant sharing of information. This has been found extremely

beneficial especially during plant startups and upsets.

QUALITY POLICY OF TATA CHEMICALS LIMITED

To provide customer satisfaction and timely delivery of quality products.

Maintain good quality management systems and incorporate regular improvements to

meet our customer changing needs.

Continuously upgrade product quality by improvements in process technology.

Develop and upgrade employee skills and provide an environment for their effective

participation through teamwork to meet our customer expectations.

Take adequate care to ensure safety at the work place, environmental preservations

and to respond to the needs of the community.

2. FIRE AND SAFETY

2.1) FIRE CHEMISTRY

The well known ―Fire triangle‖ requires the three ingredients of fire namely fuel, oxygen and

source of ignition. ―A fire is a combination of fuel, oxygen and source of ignition‖.


2.2) FIRE PREVENTION

Fire prevention can be done in three ways:

a.) Eliminate sources of ignition.

b.) Eliminate combustible substances.

c.) Eliminate air excess to combustible substances.

a.) FIRE PREVENTION THROUGH ELIMINATION OF IGNITION SOURCES:

To prevent fire the first is to remove the cause of fire. Studies made by fire insurance company

shows that majority of fires are caused by following general sources of ignition:

Electrically limited fire: Improper earthing, short circuiting, loose electrical contacts,

temporary direct connections without proper fittings, high current, over heating of electrical

equipment are among the common cause of electrically initiative fires.

Smoking ignited fire: Smoking or even carrying cigarettes/biddies/matches/lighter etc. in

the following areas is a serious offence. All non-smoking areas should carry ―NO

SMOKING‖ signboards.

Friction and overheated material: In flame proof areas, frictional fires can also be started

by the friction of moving parts of machinery which are overheated due to excess friction.

This is likely in non-lubricated and not well maintained machinery.

b.) FIRE PREVENTION THROUGH ELIMINATION OF COMBUSTIBLE

MATERIALS:

Waste and combustible materials: All combustible wastes and materials like waste paper,

cotton waste etc. accumulated after a job should be transported to waste bins and is the

responsibilities of the person doing the job that creates the wastes. Tins and cans of

flammable materials like paints, oils, spirit etc.: These should b handled carefully ensuring

that no undue spillages takes place during their uses and any spillages takes place during

their use and any spillage should be cleaned immediately.


Fueling of vehicle tanks: Engine should be always switched off while fueling a vehicle. If

diesel or petrol spills over during fueling, dry sand should covered over the spill

immediately till only dry sand is visible on the spilled area.

Waste disposal: All combustible waste must be regarded in such a way that can be disposed

off as such and not burnt.

c.) PREVENTION THROUGH ELIMINATION OXYGEN SUPPLY

Smoothening: It is a process of covering the burning area with a non-combustible substance

like asbestos or fire proof blanket, wet thick cotton blanket or sand.

2.3) CLASSIFICATION OF FIRES

Fires are classified according to the nature of fuel burning and fire extinguishing methods that

can be applied and the following is the fire classification under the Indian fire code.

CLASS “A” FIRE

CLASS “B” FIRE

CLASS “C” FIRE

CLASS “D” FIRE

CLASS “E” FIRE

CLASS “A” FIRE: Fires where the burning fuel is a cellulosic material such as wood, clothing,

paper etc. is called class ―A‖ fire.

It can be extinguished by the water and sand. Class ―A‖ fires can also be extinguished by all the

available means of extinguishing fires like foam, soda acid, dry chemical powder, carbon dioxide

etc.

CLASS “B” FIRE: Fires where the burning fuel is a flammable liquid Naphtha, petrol etc. are

categorized as class ―B‖ fire. Blanketing is a useful first aid fire control for ―B‖ class fire. Water


is forbidden as a fire fighting means on class ―B‖ fires. Foam, carbon dioxide, dry chemical

powder extinguishers are the desired means of controlling ―B‖ class fires.

CLASS “C” FIRE: Fire involving flammable like natural gases hydrogen are classified as class

―C‖ fire. The best means of extinguishing ―C‖ type fire is by stopping the gas supply to the

leaking vessels or pipe lines if possible. This must be the intermediate and very first step. Dry

chemical powder and carbon dioxide are useful in controlling ―C‖ class fire.

CLASS “D” FIRE: Fire involving material like magnesium, aluminum, zinc, potassium etc. are

classified as class ―D‖ fire. Sand buckets are useful in most cases of metallic fires. Special dry

chemical powder also works on class ―D‖ fires.

CLASS “E” FIRE: Fires involving electrical equipments are classified as ―E‖ class fires.

Only carbon dioxide and D.C.P extinguishers are used on class ―E‖ fires.

2.4) FIRE FIGHTING GADGETS AND APPLIANCES

a) CO2:- It contain under pressurized liquid carbon dioxide.

b) SODA ACID: - Contain a double container with sodium bicarbonate solution in outer

container and dilute sulphuric acid in the inner container. After the inner container both

react and produce a liquid of entrapped CO2.

c) FOAM: - Contain aluminous sulphate in inner container and sodium bicarbonate in outer

one. After cracking the container both reacts to produce carbon dioxide and the foam

stabilizer makes stable form of carbon dioxide.

d) DRY CHEMICAL POWDER: - It contains an inert dry chemical powder of sodium

bicarbonate or potassium bicarbonate or potassium chloride and diammonium phosphate

along with liquid carbon dioxide under pressure.

e) HALON/ BROMOCHLOROFLUORO METHANE: - Halon is in the form of a liquid

gas under pressure that is released on pressing the knob.

2.5) SAFETY PROGRAMME AT T.C.L


The company conducts regular programmes for safety measures, which not only creates

awareness about safety but also maintains it; the fire and safety department of T.C.L organizes

many programmes to motivate in this direction and to make the employees aware. National

safety day 4th

march is being celebrated each year with earnestness and includes various

awareness programmes, competitions and includes various awareness programmes, competitions

etc. some of these are listed below:

1. Training programmes on safety.

2. Home safety.

3. Use of safety equipments.

4. Safety quiz.

5. Safety slogan competition.

2.6) SAFETY PROVISIONS

Personal protective equipment (PPEs ): The various types of PPEs are:-

Helmet for head protection.

Goggles for eye protection.

Ear plugs and muff for ear protection.

Safety shoes for foot protection.

Gloves for hand protection.

Face shields foot protection.

Full body protection suits.

Hoods for head, neck, face, and, eye protection.

Safety belts or life belts or harness.

Breathing apparatus or respiratory protection equipment.

Fencing of machinery.

Devices for cutting of power.

Hoists and lifts.


3. BRIEF INTRODUCTION OF UREA PLANT

Tata Chemicals owns fertilizer complex at Babrala. It has adopted Snapgrogetti NH3

stripping process for the production of urea. It has two identical units (11 and 21) of the

same nameplate capacity 1750 MTPD each, so the total capacity is 3500 MTPD.

3.1) RAW MATERIAL REQUIRED FOR UREA PRODUCTION

The raw material condition at the battery limit is as under:

Ammonia:

NH3 min - 99.5%wt

Oil - 10 ppm max

Water - 0.5% wt

Carbon dioxide:

CO2 (dry basis) - 98.76% vol. min

H2 - 0.3% vol min

H2O - Saturated

Utilities characteristics

Cooling water:

Pressure (norm/design) - 3.5/6.0 kg/cm2g

Inlet temperature - 35° C

Outlet temperature - 45° C

Fouling factor - 0.0004 m2 h ° C/kcal

Electric power:


Alternating current - 11KV 50 Hz 3ph

- 3.3 KV 50 Hz 3ph

- 415 V 50 Hz 3ph

Direct Current - 115 V 1Ph

Service air:

Moister - saturated

Pressure (norm/degn) - 7/11 kg/cm2

Temperature - 40 ° C

Instrument air:

Pressure - 7/11 kg/cm2

Temperature - 40 ° C

Type - Oil free

Dew Point - -20 ° C max at 7 kg/cm2

Polished water:

Conductivity - ≤ 0.2 µs/cm

Silica (reactive) - ≤ 0.02 µs/cm

Fe - 0.01 ppm

TDS - ≤ 0.1 ppm

Oil - ≤ 0.5 ppm

pH - 7


Nitrogen:

Nitrogen plus noble gas - 99.6 % vol

CO2 - 20 ppm max

Water - 20 ppm max

Oxygen - 200 ppm max

Pressure (min/ norm) - 5/7 kg/cm2

Temperature - ambient

3.2) MANUFACTURING PROCEDURE

Urea is commercially manufactured by direct synthesis of gaseous CO2 and liq. NH3.

The urea production involves following steps:

1. Urea synthesis and pressure recovery.

2. Urea purification and medium low pressure recovery.

3. Urea concentration

- pre vacuum concentration

- Vacuum concentration

4. Urea prilling

5. Waste water treatment

1. UREA SYNTHESIS AND HIGH PRESSURE RECOVERY

For urea production raw materials (liquid ammonia and gaseous carbon dioxide) are supplied by

ammonia Plant. The liquid ammonia is pumped at high pressure through an ejector in to the

reactor. The ejector serves as drive less pump to recycle back ammonia and CO2 mixture at high

pressure known as carbamate into the Synthesis loop.CO2 mixed with small but measured

quantity of air is compressed in a fourstage compressor up to synthesis pressure. CO2 from the


compressor outlet is fed to the reactor. The NH3 and CO2 react in the reactor to form an

intermediate product, ammonium carbamate (NH4 COONH 2). This intermediate product

dehydrates to form urea and water. The oxygen in the air forms a passive oxide layer on the inner

surface of the vessel to prevent corrosion by carbamate and urea.

The reaction products from the reactor overflow to the stripper where the unconverted carbamate

is decomposed back in to the constituents with the help of the heat supplied by MP steam. The

stripper is basically a falling film exchanger with urea solution on the tube side and MP steam on

the shell side. The Urea solution obtained at the bottom flows to MP section through a level

control valve. The vapours from the stripper top enter the HP carbamate condenser along with

the carbamate solution Again and in the process releasing a large amount of heat of

condensation, which is utilized to generate the low-pressure steam on the shell side. Vapours

consisting mainly of inerts are sent from the carbamate separator to the bottom of the MP

decomposer to passivate the MP section.

2. UREA PURIFICATION

Urea purification takes places in two stages. One is known as MP section and the other is known

as LP Section.

MEDIUM PRESSURE SECTION

Urea solution from the bottom of the stripper enters the MP decomposer. During the expansion

most of the remaining carbamate flashes forming the NH3 and CO2 vapours, thereby

concentrating the urea solution. The vapours from the MP decomposer top flow to pre vacuum

concentrator shell side and from pre vacuum Concentrator to MP condenser shell side. Prior to

the entry of the vapours in the pre vacuum concentrator the vapours get mixed with the low

concentration carbamate solution from the LP section. The partly condensed gas mixture from

MP condenser outlet goes to MP absorber where the CO2 is stripped from the NH3 vapors and

the pure NH3 vapors from the MP absorber flow to ammonia condenser. The solution at the


bottom of the MP absorber provides the suction for the HP carbamate pump. Ammonia

condenser has cooling water on tube side.

From ammonia condenser both vapour and liquid flow to the ammonia receiver tank. The

receiver tank receives fresh ammonia from the ammonia plant. The inert gases saturated leaving

the receiver enter the ammonia recovery tower.

Here ammonia is further condensed by direct contact with cold ammonia from the battery

limit.The inert with residual ammonia from the tower are sent to MP inert wash tower via a

condenser. The ammoniacal solution collected at the bottom is recycled back to the MP absorber.

LOW PRESSURE RECOVERY

The urea solution from MP decomposer bottom enters the LP decomposer after expansion

through a level controller. Consequently most of the residual carbamate is decomposed and in

the process urea solution gets concentrated. The remaining carbamate is decomposed in falling

film exchanger, which is a part of LP decomposer.

The vapours from the LP decomposer enter the LP condenser where they get cooled and

liquefied. Prior to entry of LP off gases in LP condenser the vapours get mixed with aqueous

solution from wastewater section. The vapours thus formed get condensed in LP condenser goes

to carbonate solution tank from where it is sent back to MP condenser. The inert gases in the

tank contain considerable amount of ammonia and thus are absorbed in cool condensate before

being sent to the vent stack. The urea solution at the bottom of LP decomposer is sent to pre

vacuum concentrator through a level controller valve.

3. UREA CONCENTRATION

PRE VACUUM CONCENTRATOR

The urea solution from LP decomposer enters the pre vacuum concentrator, which is an

exchanger with urea solution from the LP section on tube side and MP decomposer off-gases on

the shell side. The MP decomposer off-gases give their heat and the urea solution gets

concentrated in the process. The pre vacuum concentrator operates under vacuum and the


vapours from the top are condensed in the pre vacuum condenser. The vapours condensing in the

pre vacuum condenser are collected at the bottom in vacuum system tank and the liquid is sent to

the wastewater section. The concentrated urea solution at the bottom is sent to the vacuum

concentrated section.

VACUUM CONCENTRATION

The urea solution from the pre vacuum section bottom gets further concentrated up to the

concentration required for prilling in two vacuum concentrators in series. The heat for

concentrating the urea solution is supplied by low-pressure steam. The vacuum is maintained in

both the stages with the help of ejectors and condensers. The urea solution from the outlet of

second vacuum concentrator has 99.7 % (w/w) concentrations and is pumped to prilling section.

The vapours from both the stages get condensed in the condensers and are sent to the wastewater

section.

4. UREA PRILLING

The urea melt from the second vacuum concentrator is sent to the prilling bucket. The urea melt

comes out from the bucket in the form of liquid drops and they fall along the prilling tower. The

drops get solidified and cooled by the countercurrent flow of air from the bottom of prilling

tower. The solidified urea melt drops known as urea prills, fall on the prilling tower bottom.

These prills are collected by a rotating scrapper and are sent to the bagging plant with the help of

belt conveyors. The heated air containing few ppm of NH3 is released from the top in to the

atmosphere.

5. WASTE WATER TREATMENT

The liquid waste containing water, urea, ammonia and carbon dioxide from the process, the

condensate from vacuum and pre vacuum concentration ejector/condensers are collected in a

wastewater tank. From here it is transferred to the distillation tower where it is fed in the upper

portion of the distillation tower. The stripping medium is low-pressure steam fed at the bottom of

the tower. The ammonia stripped wastewater is then pumped to the hydrolyser where the urea in

the wastewater is hydrolyser to be converted back in to ammonia and carbon dioxide. The

hydrolyzation takes place with the help of the superheated steam. The wastewater from the


hydrolyser outlet contains only few ppm of urea but still has ammonia in it. So the wastewater

from the hydrolyser outlet is again fed to the lower portion of the distillation column where the

remaining ammonia is stripped off and the wastewater at the distillation tower at the bottom

contains only few ppm of ammonia and urea.

This treated water is sent to O&U plant for reuse. The vapours from the distillation tower and

hydrolyser get condensed in the overhead condenser and are recycled back to the LP section and

a part of it is used as reflux for distillation column. The distillation column is a tray column

PROCESS FLOW DIAGRAM

Fig.3.2.1. Process Flow Diagram of Urea Plant

3.3) STEAM AND CONDENSATE SYSTEM

The steam networks provided in the urea plant are:

1. Superheated steam (KS) network at P = 110 kg /cm2

g & T = 510°C


2. Superheated steam (HS) network at P = 37 kg /cm2

g & T = 381°C

3. Saturated steam (MS) network at P = 22 kg /cm2

g & T = 219°C

4. Saturated steam (LS) network at P = 3.5 kg /cm2

g & T = 147°C

5. Saturated steam (KS) network at P = 4.7 kg /cm2

g & T = 160°C

KS NETWORK:

The steam is available at urea plant battery limit and is utilized to drive the CO2 compressor

turbine. It may be used to provide the MS steam in case of failure of turbine extraction steam.

HS NETWORK

This steam is available at the point battery limit and is utilized in hydrolyzer.

MS NETWORK

This steam is extracted from the carbon dioxide compressor turbine and is the superheated to

make it saturated. This steam is utilized in the stripper and MP decomposer.

LS NETWORK

This steam is produced in the HP carbamate condenser shell & is used in the following

equipment / systems:

1. LP decomposer

2. First vacuum concentrator

3. Second vacuum concentrator

4. distillation tower bottom

5. Prevacuum / vacuum system ejectors

6. Steam tracing

7. Steam jackets

8. MP start up lines

9. MP inert gas wash tower vent line


10. Steam condensate collector tank

11. Blow down vents, ME-14,ME-15, ME-21

12. PSV flushing

13. Mechanical seal / jacket flushing of P-08, P-09, & P-20

14. utilities points

LMS NETWORK:

This steam is produced by boosting LS pressure with the help of an ejector with MS as motive

fluid. The steam is utilized in the MP decomposer.

CONDENSATE COLLECTION

Turbine condensate is exported to O&U for steam generation. MS & HS condensate known as

MC & HC respectively is utilized for LS generation in HP carbamate condenser shell. LS

condensate known as LC from all the sources in the plant is collected in a common tank as steam

condensate tank. From where it is used for flushing purpose and the excess condensate is

exported to O&U.

3.4) FLUSHING NETWORK

Condensate in the steam condensate tank is utilized to provide flushing water requirement in all

the section of the plant. There are three types of network:

KW Network: Flushing water at pressure of about 180 kg /cm2 a

HW Network: Flushing water at pressure of about 25 kg /cm2 a

LW Network: Flushing water at pressure of about 10 kg /cm2 a



4) PROJECT

4.1) To Carry out the energy balance of Urea plant


TO CARRY OUT THE ENERGY BALANCE OF UREA PLANT

PROJECT SUMMARY

The project assigned to me is ‗To Carry Out The Energy Balance of Urea Plant‘.I was assigned

this project by Mr.Azaz Ali, the head of department of urea plant.Now the urea plant here at Tata

Chemicals Limited has two exactly identical units viz. 11 and 21 within the plant.Both the units

work on the same load of raw materials and energy and have the same installations.Therefore it

is prudent to surmise that both the units would have the same or nearly same concentration of

gases in the flows analogus to both the sister units.

The process used here for urea manufacturing is Snamprogetti process.

The urea production involves following steps:

1 Urea synthesis and pressure recovery.

2 Urea purification and medium low pressure recovery.

3 Urea concentration

4 pre vacuum concentration

Vacuum concentration

5 Urea prilling

6 Waste water treatment

The material balance of every section has already done in detail manner.Now the task was to

Carry Out The Energy Balance of Urea Plant.


Approach:

The way forward for tackling this problem was to first get a design data sheet of the plant.Since

the plant was updated to a new capacity of 2*1750 MTPD as against the old 2*1225 MTPD it

was imperative only to work with the new design data sheet.The idea was to first find the design

flowrates of various components at various points and then to find out the temperature at various

points.

FLOWRATES OF PROCESS FLUID

The flowrates of process fluids were obtained from the Control room as well as from the

PROCESS FLOW DIAGRAMS(PFD).

TEMPERATURE MEASUREMENTS

The temperature of process fluids were obtained from the Control room as well as from the

PROCESS FLOW DIAGRAMS(PFD).

SPECIFIC HEAT DATA

The specific heats of various components were obtained from the data sheets in the technical

library.Since there is a small variation in Cp value with temperature.I assume Cp of any

component at three diff. temperature ,then I get three variable with three equations and after

solving them I get the value of a,b.and c .

Hence,although this approach may not be entirely accurate ,it will still be within an extremely

small range of error of the actual value.

PROCEDURE

The heat exchanged by the process side is calculated by the formulae:

Q = mcp(Tin – Tout) [mass flowrate*specific heat *temp.difference]


Material Balance Of Urea Plant.

Urea production per day = 3800 MTPD

CO2 conversion = 64%

CO2 requirement per day = 57954 kg/hr

NH3 requirement per day = 127804 kg/hr

Compound Chemical formula Molecular Weight(kg/kmol)

Ammonia NH3 17

Carbon di oxide CO2 44

Ammonium Carbamate NH2COONH4 78

Water H2O 18

Urea NH2COONH2 60

Table 1 Compound in Urea Manufacturing

Input ratio to reactor NH3:CO2

Molar ratio 4: 1

Weight ratio 68: 44

Reactions involved in the process

2 NH3 + CO2→ NH2COONH4 + HEAT


Sch 2 1 1

Mass 34 44 78

Wt% 0.436 0.564 1.000

NH2COONH4 + HEAT → NH2CONH2 + H2O

Sch 1 1 1

Mass 78 60 18

Wt% 1.000 0.769 0.230

5.0 Heat Balance Calculation

5.1 Main Process Energy Balance

2 NH3 + CO2 NH2COONH4 + HEAT -84 KJ/mol

NH2COONH4 + HEAT NH2CONH2 + H2O +23 KJ/mol

2NH3 + CO2 NH2CONH2 + H2O -60 KJ/mol

Ammonia Liquid

T (ºC) 60 80 112

Cp (KJ/KgK) 5.6 5.87 8.6

Ammonia Vapour

T (ºC) 87 127 167 207

Cp (KJ/KgK) 2.2 2.3 2.37 2.44


CO2(g)

T (ºC) 27 127 227

Cp (KJ/KgK) 0.84 0.94 1.01

Urea Vapour

T (ºC) 80 120 200

Cp (KJ/KgK) 1.26 1.36 1.56

Urea Liquid

T (ºC) 80 120 200

Cp (KJ/KgK) 1.4 1.6 2.1

Urea Solid

T (ºC) 27 77 127

Cp (KJ/KgK) 1.56 1.8 2.04

Water Liquid

T (ºC) 27 127 177

Cp (KJ/KgK) 4.18 4.26 4.39

Cp of the Carbamate = 2.3 KJ/KgK


For NH3 liquid

Cp = a + bT + cT2

5.6 = a + 333b + 3332 c (1)

5.87 = a + 353b + 3532 c (2)

8.6 = a + 385b + 3852 c (3)

From (1), (2) & (3)

a = 163.44 b = - 0.9338 c = 1.38*10-3

For NH3 gas

Cp = a + bT + cT2

2.2 = a + 360b + 3602 c (4)

2.3 = a + 400b + 4002 c (5)

2.44 = a + 480b + 4802 c (6)

From (4), (5) & (6)

a = 0.4 b = 7.25*10-3

c = -6.25*10-6

For CO2 gas

Cp = a + bT + Ct2

0.84 = a + 300b + 3002 c (7)

0.94 = a + 400b + 4002 c (8)

1.01 = a + 500b + 5002 c (9)

From (7), (8) & (9)

a = 0.36 b = 2.05*10-3

c = -1.5*10-6

For Urea

Cp = a + bT + cT2

1.4 = a + 353b + 3532 c (10)

1.6 = a + 393b + 3932 c (11)

2.1 = a + 473b + 4732 c (12)


From (10), (11) & (12)

a = 1.08 b = -2.77*10 -3

c = 1.04*10-5

Reactor (R-01)

Urea formation heat by decomposing Ammonium Carbamate

∆Hf = 79279 *

= 30390.28 kJ/hr

Ammonium Carbamate production in the reactor

= *79279

= 103,062.7 Kj/hr

Ammonium Carbamate formation heat

∆Hf = 103062.7* = -110990.6 KJ/hr

Heat required to increase raw material from 178°C to 188°C

= (12,7804)*[ ∫(163.44 – 0.9338T + 1.38 * 10-3T2)dT ] +(23333)*(461-451) +

(57954 + 42,284)*[∫(0.36 + 2.05*10-3T ― 1.5*10-6T2)dT]

= 3818763.96 KJ/hr

Energy required to reactor = 30390.28 – 110990.6 + 3818763.96

= 3738163.66 KJ/hr

Stripper (E-01)

Decomposition energy of Ammonium Carbamate

(251373 )* = 270,709.38 Kj/hr

Heat absorbed by Carbamate by temp.increase from 461K to 477K


= (79,279)*[∫(1.08 – 2.77*10-3

T + 1.04 *10-5

T2)dT ]+

(45,665)*[ ∫(163.44 – 0.9338T + 1.38 * 10-3T2)dT] + 43,007*4.4*(477-461) +

(12,843)*[∫ (0.36 + 2.05*10-3T ― 1.5*10-6T2)dT]

= 79,279*32.5 + 45,665*390.7 + 3,027,692.8 + 204,414.58

= 2577186.6 + 206852657.8 + 3,027,692.8 + 204,414.58

= 212,661,951.8 Kj/hr

Heat absorbed by carbon Dioxide by increasing the temp. from 461°C to 463°C

= (12843)*∫10.36(463-461) + 2.05*0.001*0.5*(4632 – 461

2) – 1.5 *10*-6*(463

3 -461

3)*0.333

= 12843*21.98

=282,289.14 Kj/hr

Heat absorbed for Ammonia Vapourisation

= 37214*160

= 5954240 Kj/hr.

Energy required for stripper = 270,709.38 + 212,661,951.8 + 282,289.14 + 5954240

= 219,169,190.3 Kj/hr

Carbamate Condenser:(E-05)

Heat absorbed by Carbamate by temp.increase from 368K to 428K

(13169)*∫(0.36 + 2.05*0.001T – 1.5 *10-6

T2)dT + (28138)*[∫(163.44 – 0.9338T + 1.38*10

-

3T

2)dT] + 19283*4.4*(428-368)

= 742,731.6 + 42,550,976.92 +50,90,7 12

Heat released by CO2 =

29257*∫(0.36 + 2.05*0.001T – 1.5 *10-6

T2)dT

= -1001871.7 Kj/hr


Heat released by water

= 19263*4.4*(428-463)

= -2969,582 Kj/hr

Condensation heat & Sensible heat released by NH3 =

37,214*760 + 37,214*[∫(0.4+(7.25*10-3

)T-1.5*10-6

T2)dT]

= 37214*760 + 37,214*-116.72

= 23,939,021.92 Kj/hr.

Heat released from water

= 4,110*4.4*(428-463)

= -632,940 kj/hr.

Heat released from Carbamate condenser =

742,731.6 +42,550,976.92 + 5090,712 -1001871.7 -2,969,582 +23,939,021.92-632,940

= 67,719,048.72 Kj/hr.

Carbamate Separator(MV-O1) :

Heat released from up flow (190°C to 155°C)

= 4501*[∫(163.44 – 0.9338T + 1.38*10-3

T2)dT]

= -5,934,540.99 Kj/hr

Heat released from down flow (190°C to 155°C)

60,581*[∫(163.44 – 0.9338T + 1.38*10-3

T2)dT]

+ 42,284*[*∫(0.36 + 2.05*0.001T – 1.5 *10-6

T2)dT

+23,251*4.4*(428-463)

= - 85,345,693.06 Kj/hr

Energy loss = -5,934,540.99 - 85,345,693.06 = -91,280,234.05 Kj/hr


Low pressure Decomposer (E-03):


= 123723*84/78 = 133,240.15 KJ/hr

Heat absorbed for Ammonia Vapourization

= 6006 *210 = 1261260 KJ/hr

Heat released from Urea (160°C - 142°C)

= (79279)*[∫(1.08 – 2.77*10-3

T + 1.04 *10-5

T2)dT ]

= 79,279*-31.62 = - 2506,951.85 KJ/hr

Heat released by Ammonia (160°C - 142°C)

= 7849*[∫(163.44-0.9338T + 1.38*10-3

T2)dT]

= -2080,640.037 KJ/hr

Heat released from water (160°C - 142°C)

= 34459*4.3*(415-433)

= - 2,667,126.6 KJ/hr

Heat released from carbon – di-oxide (160°C - 142°C).

= 2136*[∫(0.36 + 2.05*10-3T ― 1.5*10-6T2)dT]

= -36,179.28 KJ/hr

Heat released by LPD = 133,240.15 +1261260 - 2506,951.85 -2080,640.037

- 2,667,126.6 -36,179.28

= -5,896,397.61 KJ/hr


MP Decomposer (E-02 A/B):


= (180794 – 123723)* = 61,461.07 KJ/hr.

Heat absorbed for Ammonia vapourisation

= 42317*210 = 8886570 KJ/hr

Heat released from Urea (204°C - 160°C)

= (79279)*[∫(1.08 – 2.77*10-3

T + 1.04 *10-5

T2)dT ]

= 79,279*-117.54 = -9318998.45 KJ/hr

Heat released from water (204°C - 160°C)

= 43007*4.3*(160-204) = -8136924.4 KJ/hr

Heat released by Ammonia (204°C - 160°C)

= 45665*[∫(163.44-0.9338T + 1.38*10-3

T2)dT]

= 45665*-1808.4 = -8258104.39 KJ/hr.

Energy loss = 61,461.07 + 8886570 – 9318998.45 – 8136924.4 – 8258104.39

= -16,765,996.17 KJ/hr


M.P.Absorber(C-01):

Condensation heat released by NH3

= (50308-29713)*(-200)

= -4119000 kj/hr

Energy loss due to reduce temperature from 85°c to 80°c

= 28138*[∫(163.44 – 0.938T + 1.4*10-3

T2)dT] + 13169[(0.36+ 2.05*10

-3T -1.5*10

-6T

2)dT ]

+ 17783*4.4*(80-85)

= 28138*-22.18 +13169*-8.15 + 17783*4.4*(80-85)

= -1122,654.19 Kj/hr.

Energy released from M.P.ABSORBER(C-01)

= -4119000 -1122,654.19 = -5,241,654.19 Kj/hr

Prevacuum Separator(MV-29/E-29)

Heat released from UREA =

79279*1.96*(102-142) = -6,215,473.6 KJ/hr

Heat released from Water =

(29745+8690)*4.25*(102-142) = -6,533,950 KJ/hr

Heat absorbed by water Vapourisation =

15856*2,258 = 35,802,848 KJ/hr

Total Heat gain = -6215,473.6-6,533,950 + 35,802,848

= 23,053,424.4 KJ/hr

M.P Steam load

S6 *1972 = 23,053,424.4

S6 = 11,690.38 KJ/hr


1st Vacuum Separator (MV-06/E-14):

Heat absorbed by water vapourisation

= 9720*2702.4 = 26,267,328 KJ/hr

Heat absorbed by Urea & Water

= 79,279*2*(128-102) + 13,889*4.25*(128-102)

= 4,122,508 + 1,534,734.5 = 5,657,242.5 KJ/hr

Energy loss = (26,267,328 + 5,657,242.5)*0.01 = 319,245.71 KJ/hr

Total energy requirement

= (26,267,328 + 5,657,242.5 + 319,245.71) KJ/hr

= 32,243,816.21 KJ/hr

3.5 kg/cm2

LS steam load

S7 * 2109 = 32,243,816.21

S7 = 15,288.68 KJ/hr

2nd

Vacuum Separator (MV-07/E-15):

Heat absorbed by water vapourisation

= 5115*2706.28 = 13,842,622.2 KJ/hr

Heat absorbed by Urea & Water

= 79,329*2*(138-128) + 5,313*4.25*(138-128)

= 1,586,580 + 225,802.5 = 1,812,382.5 KJ/hr

Energy loss = (13,842,622.2+ 1,812,382.5)*0.01 = 156,550.047 KJ/hr

Total energy requirement

= (13,842,622.2+ 1,812,382.5 + 156,550.047) KJ/hr

= 15,811,554.75 KJ/hr

3.5 kg/cm2

LS steam load

S8* 2109 = 32,243,816.21


S8 = 7,497.18 KJ/hr

Prilling Tower (ME-06)

Heat removed from Prilling Tower =

79,329*2*(128 – 138) + 5,313*4.25*(128 – 138)

= -1,586,580 – 225,802.5

= - 1,812,382.5 KJ/hr

Process Waste water treatment unit.

Heat requirement of waste water treatment unit =

58396 * 4.2*(147-128) + 58,396*2258

= 63,000.5 + 131,858,168

= 131,921,168.5 KJ/hr


8.0 Tabulated heat balance

Input Energy KJ/hr

Heat supplied to reactor 3738163.66

Heat supplied to stripper 219,169,190.3

Heat out from Carbamate Condenser 67,719,048.72

Heat supplied to HPD

Heat supplied to prevacuum separator 23,053,424.4

Heat supplied to 1st vacuum separator 32,243,816.21

Heat supplied to 2nd

vacuum separator 15,811,554.75

Total input energy 340,735,198

Output Energy KJ/hr

Heat out from Separator 91,280,234.05

Heat out from Carbamate Condenser

Heat out from MPD 16,765,996.17

Heat out from Absorber 5,241,654.19

Heat out from prilling tower 1,812,382.5

Heat out from waste water 131,921,168.5

Heat out from LPD 5,896,397.61

Total output energy 251,286,689

Difference between input and output energy = 89,448,508.98

Total heat input is greater than total heat output.So this difference

is due to heat generated in the reaction.But the amount of theoretical heat generated in the

reaction is much higher than this value.That difference between actual and theoretical value is

happens because of heat losses ocuured during the reaction.


5) CONCLUSIONS AND RECOMMENDATIONS


4.1) SIMULATION OF MEDIUM PRESSURE ABSORBER(C-01):

This project deals with the steady state simulation of ‗Medium Pressure Absorber(C-01)‘ of the

urea plant using Aspen plus simulator. Aspen plus is a process modeling tool for conceptual

design, simulation, optimization and performance monitoring for chemical, polymer, specialty

chemical, metals and minerals, and coal power industries. The unique combination of sequential-

modular and equation-oriented solution technologies in Aspen plus facilitate simulation of wide-

scale, integrated chemical processes. Aspen plus can predict the output conditions based on the

given input and process conditions and hence we can use it as a tool in process improvisation.

We can also optimize a process using Aspen Plus's various in-built optimization algorithms.

Using these optimization techniques we can improve the performance of various processes by

manipulating the operating variables.

The purpose of the simulating this absorber is to calculate the amount of absorption of carbon

dioxide and water contained in the vapors of mixed stream coming from medium pressure

condenser (E-07) outlet enter into the medium pressure absorption column (C-01), so as to

increase recovery of ammonia from the process. In this project, the simulations are carried out

based on design conditions. The saved aspen simulation files can be used by anyone to predict

the behavior of the simulated sections

The first step in simulation is to build the process flow diagram in the user interface. Fig. 4. 1.1

shows the process flow diagram of the medium pressure absorber (C-01). The process mixed

stream from medium pressure condenser (E-07) outlet enters the absorber, from the middle of the

column. The vapors containing ammonia, carbon dioxide, water and inerts are separated out from

liquid and rises towards top of the column. Fresh ammonia and ammonia solution are entered on

tray 1 and 2 resp. from top of the column. Whenever reflux gets contacted with rising vapors, it

absorbs carbon dioxide and water. Vapors are drawn from the top of column containing

ammonia, inerts and few ppm of carbon dioxide and water. Liquid solution is drawn from bottom

of the column containing ammonia, carbon dioxide and water.

In this case the equilibrium steady state simulation of medium pressure absorber (C-01) is carried

out. The RADFRAC ABSORBER model from the steady-state simulator ASPEN PLUS, version

2006 was taken to simulate the process. RADFRAC is based on a rigorous equilibrium-stage

model for solving the MESH (Material balance, vapor – liquid Equilibrium, mass fraction

Summations and Heat balance) equations.


Simulation of the design data on Absorber Column (C-01):

The input data for the components entering from shell side of Pre Vacuum Column (E-29) shell

side:

Temperature = 85°C

Pressure = 18.22 kg/cm2g

Ammonia flow rate = 78996 kg/hr

Carbon di-oxide flow rate = 13169 kg/hr

Water flow rate = 16917 kg/hr

The input data from the M.P Ammonia absorber (E-11)

Temperature = 37°C



The input data from the Ammonia Solution

Temperature = 50°C



The M.P absorber input is :

Height : 9 m

Dia. : 1.74 m

No.of Trays : 4

Type of Trays :Bubble cap

Properties Specified : ELECNRTL (Electrolytic Non Random Two Liquid)


Simulation was run on the above input data and the following results were obtained.The

results are tabulated on the following page.

Fig. 4. 1. 1. Medium Pressure Absorber (C-01)


Table 4. 1. 1: Streams Results


Table 4. 1. 2: Mass and Energy Balance

Table 4. 1. 3: Top stage parameters

Table 4. 1. 4: Bottom stage parameters

Table 4. 1. 5: Split fraction of components


Table 4. 1. 6: Temperature, Pressure and Flow rate Profiles

Table 4. 1. 7: Vapor Compositions of Components

Table 4. 1. 8: Liquid Compositions of Components


Table 4. 1. 9: K-Value Profiles


Some of the plots for various simulation results are as follows:

Fig. 4. 1. 2. Variation of temperature with stages


Fig. 4. 1. 3. Variation of column pressure with stages

Fig. 4. 1. 4. Variation of total liquid flow rate with stages


Fig. 4. 1. 5. Variation of total vapor flow rate with stages


Fig. 4. 1. 6. Liquid composition profiles

Fig. 4. 1. 7. Vapor composition profiles


5) CONCLUSIONS AND RECOMMENDATIONS

For 3500 MTPD capacity; ranges are found for column pressure would be 17 to 18 kg/cm2 a.

P5NH3 flowrate would be 5500 to 6500 kg/hr and C1mixin temperature would be 84°C to 87 °C.

Output of C1vapor temperature would be in the ranges of 42.4°C to 44.5°C and corresponding

C1vapor flow rate would be in the ranges of 31100 to 31700 kg/hr. Output of C1liquid

temperature would be in the 78°C to 81°C and corresponding C1 liquid flow rate would be in the

ranges of 55600 to 56500 kg/hr.


6) REFERENCES

1) Urea Manual, TATA Chemicals Ltd, Babrala, 1999.

2) Fire and Safety manual of TCL, Babrala.

3) ASPEN plus Manual 2006.

4) McCabe Warren L., Smith Julian C., Harriott Peter, Unit Operations of Chemical

Engineering, 6th

Edition, McGraw-Hill Book Co.-Singapore, International Edition, 2001.

5) Richardson, J. F.; Harker, J. H.; Buckhurst, J. R., Particle Technology and Separations

Processes, Vol. 2, 5th

Edition, Butterworth-Heinemann, Elsevier, 2006.

6) Perry, R.H., and Green, D.W., Perry’s Chemical Engineering Handbook, 7th

Edition,

Tata McGraw-Hill, 1999

7) Treybal, R.E., Mass Transfer Operations, 3rd

Edition, Tata McGraw-Hill, 1980

8) Smith, J.M., Abbott, M.M., Vanhess, H.C., Chemical Engineering Thermodynamics, 6th

Edition, Tata McGraw-Hill, 2003.

9) MARTYN S. RAY;DAVID W. JOHNSTON – Chemical engineering Design Project:

A Case Study Approach


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