urea final report

Comprehensive design project

Group Members:

G.A.M.C. Ariyathilaka 050029P

A.N. Buddhika 050050V

K.R.M.G. Kahatapitiya 050192G

K.D.N. Karunarathna 050206G

D.D.D.P.Sandasiri 050404L

Project Coordinator:

Dr. Maneesha Gunasekara

UREA MANUFACTURING PLANT

CH 4200 – Comprehensive Design Project

Urea Manufacturing Plant

Comprehensive design project I

ACKNOWLEDGEMENT

First of all we would like to grant our heartiest gratitude to our project coordinator,

Dr. Maneesha Gunasekara (lecturer- Chemical & Process Engineering department, University of

Moratuwa) for all the guidance and support that she has given us to complete this design project

in a successful manner. Dear Madam, please expect our sincere thanks for your kind hearted

support and genuine friendly attitude shown towards our work. Thank you very much for

spending your precious time to share your knowledge & experience with us.

Then again, we must not forget all the staff members of Chemical & Process Engineering

department, including the head of the department Dr. Jagath Premachandra , for all the assistance

and support given us for accomplish the project. Without your support we may have not come

this far, so please accept our sincere thanks .Also we thank the level-4, semester-1 coordinator,

Dr. Suren Wijekoon, lecturer- Chemical & Process Engineering Department, University of

Moratuwa. And finally, a special thank should be given to the staff of Sri Lanka Custom Office

who provide us data related to urea imports.

Thank you,

G.A.M.C. Ariyathilaka

A.N. Buddhika.

K.R.M.G. Kahatapitiya

K.D.N. Karunarathna

D.D.D.P.Sandasiri


Comprehensive design project II

PREFACE

The final year project is task, where we apply our knowledge & experience, gained throughout

the four year degree course, in a practical scenario. Here we have done it in our best capacity. It

is a step which finally determines the capability to perform as chemical engineers.

The ultimate goal of the final year design project on urea manufacturing plant is to

find out the feasibility of setting up such a plant in Sri Lanka. In Sri Lanka urea is being used as

a fertilizer in the agriculture sector. Other than as a fertilizer, urea is hardly used in any industry

or any other sector even though urea has number of industrial and commercial uses. Sri Lanka

imports urea from other countries such as Saudi Arabia, India, and China. The total import

volume of urea is around 330,000 MT per annum. Sri Lankan government gives urea fertilizer in

subsidized price for farmers. From the budget 2008, Sri Lanka allocated 15 billion rupees for

fertilizer subsidies.

However in the past with the establishment of The Urea Plant at Sapugaskanda, Sri

Lanka became self sufficient in fertilizer requirements of the country. In 1982, the annual

production of urea at Sapugaskanda factory was 310,000 tons. Then the country's annual demand

was only 290,000 tons. The excessive production of 20,000 tons of urea was exported earning

foreign exchange around Rs. 200 million. In 1982 the annual savings of State Fertilizer

Corporation stood at Rs.750 million. In addition it had provided direct employment opportunities

to 1,250 workers. Sapugaskanda Urea plant was closed in January 1987.

In the world point of view urea is produced on a scale of some 100,000,000 tons per

year worldwide. Urea is produced from synthetic ammonia and carbon dioxide. Urea can be

produced as prills, granules, flakes, pellets, crystals, and solutions. More than 90% of world

production is destined for use as a fertilizer. Urea has the highest nitrogen content of all solid

nitrogenous fertilizers in common use (46.7%).Urea is highly soluble in water and is, therefore,

also very suitable for use in fertilizer solutions. Solid urea is marketed as prills or granules. The

advantage of prills is that, in general, they can be produced more cheaply than granules, which,

because of their narrower particle size distribution, have an advantage over prills if applied

mechanically to the soil.

In Sri Lanka establishing urea manufacturing plant has many advantages. It will

have greater effect on country‟s economy, development in agriculture sector, providing

employment and other tangible and intangible benefits. But without having an ammonia


Comprehensive design project III

production process from which in most cases raw materials for urea manufacturing (ammonia

and carbon dioxide) is derived, it is rather difficult and unfeasible to establish a urea plant along

considering the availability of raw materials. Considering the project it is presumed that

ammonia and some instance carbon dioxide is imported.

According to the current demand of Sri Lanka, the urea demand of the country with

in next five years will be around 350,000 MT per annum. So we decided to design a Urea

manufacturing plant to fulfill that requirement. Our plant is operated for 328 days per year. And

rest of the year can be allocated for maintenance of the plant.

Constructing of this kind of manufacturing plant will enhance the country‟s

development since the ultimate product urea is directly related with country‟s economy and

growth in agriculture sector and a utility for many other industries. On the other hand the global

demand for urea is increasing rapidly; specially in Asian countries. Under those circumstances

we present the final year comprehensive design project which would be beneficial for country‟s

development.

The design project is combined in to this report, consist of 8 chapters. Chapters

include Literature survey, Process selection and Economic aspects, Process description and Flow

sheet, Site selection, Mass balance calculation, Material flow sheet, Heat balance calculation,

Tabulated heat balance.


Comprehensive design project IV

CONTENTS Page No

Chapter 01

1.0 Literature Survey.……………………………………………………………….. 02

1.1 Urea …………………………………………………………………………….. 02

1.1.1 Synthetic urea ………………………………………………………. 02

1.1.2 Commercial production of urea …………………………………….. 02

1.1.3 Chemical characteristics of urea …………………………………… 03

1.1.4 Physical characteristics of urea …………………………………….. 04

1.1.5 Raw materials of urea manufacturing ……………………………… 04

1.1.5.1 Ammonia …………………………………………………. 04

1.1.5.1.1 Ammonia Production ………………………… 05

1.1.5.1.2 Ammonia storage ……………………………. 06

1.1.5.2 Carbon Dioxide ………………………………………....... 06

1.1.6 Applications of urea……………………….……………………….. 06

1.1.6.1 Agricultural use …………………………………………… 06

1.1.6.1.1 Advantages of Fertilizer Urea……………….. 07

1.1.6.1.2 Soil Application and Placement of Urea…….. 07

1.1.6.1.3 Spreading of Urea…………………………… 08

1.1.6.2 Industrial use……………………………………………… 08

1.1.6.3 Further commercial uses………………………………….. 08

1.1.6.4 Laboratory use……………………………………………. 10

1.1.6.5 Medical use………………………………………………. 10

1.1.6.5.1 Drug use …………………………………….. 10

1.1.6.5.2 Diagnostic use ……………………………… 10

1.1.6.6 Textile use………………………………………………… 10

1.2 Global production and consumption of Urea………………………………….. 11

1.2.1 Range of global uses of urea……………………………………….. 14

1.3 Urea Prices…………………………………………………………………….. 15

1.4 Urea Production and Consumption in Sri Lanka……………………………… 15

Chapter 2

2.0 Process Selection & Economic Aspects……………………………………….. 18

2.1 Feasibility Study……………………………………………………………….. 18


Comprehensive design project V

2.1.1 Introduction………………………………………………………… 18

2.1.2 Technical & Economic Feasibility………………………………… 19

2.1.2.1 Plant Capacity……………………………………………. 19

2.1.3 Social & Environmental Feasibility………………………………… 20

2.1.4 Plant Components………………………………………………….. 20

2.2 Process Selection………………………………………………………………. 21

2.2.1 Conventional Processes……………………………………………. 21

2.2.1.1 Once through Process…………………………………….. 21

2.2.1.2 Conventional Recycle Process …………………………… 21

2.2.2 Stamicarbon CO2 – stripping process……………………………… 24

2.2.3 Snamprogetti Ammonia and self stripping processes……………… 27

2.2.4 Isobaric double recycle process …………………………………… 28

2.2.5 ACES process……………………………………………………… 29

2.2.6 Process comparison………………………………………………… 29

2.2.6.1 Advantages of ACES Process……………………………. 30

Chapter 3

3.0 Process Description and flow sheet…………………………………………… 32

3.1 Process Description – ACES Process…………………………………………. 32

3.1.1 ACES Urea plants available in the world………………………….. 34

3.2 Main component of the process………………………………………………. 34

3.2.1 Reactor…………………………………………………………….. 34

3.2.2 Stripper…………………………………………………………….. 34

3.2.3 Carbamate Condenser……………………………………………… 35

3.2.4 Scrubber…………………………………………………………… 35

3.2.5 Medium Pressure Decomposer…………………………………….. 35

3.2.6 Low Pressure Decomposer………………………………………… 35

3.2.7 Medium Pressure Absorber………………………………………... 35

3.2.8 Low Pressure Absorber…………………………….……………… 36

3.2.9 Flash Separator…………………………………………………….. 36

3.2.10 Lower Separator………………………………………………….. 36

3.2.11 Upper Separator………………………………………………….. 36

3.2.12 Granulation Plant…………………………………………………. 37

3.3 Typical product quality………………………………………………………... 38


Comprehensive design project VI

Chapter 4

4.0 Site Selection & Plant Layout……………………………………………….… 40

4.1 Site Selection…………………………………………………………………… 40

4.1.1 Availability of raw materials……………………………………..… 40

4.1.2 Infrastructure facilities……………………………………………… 41

4.1.3 Legal obligations enforced by relevant authority or the government 42

4.1.4 Environment and Climate Conditions……………………………… 42

4.1.5 Labour Force availability…………………………………………… 42

4.1.6 Social considerations………………………………………………. 42

4.1.7 Waste Management……………………………………………...… 43

4.2 Plant Layout …………………………………………………………………… 43

4.2.1 Importance …………………………………………………..…….. 43

4.3 Environmental Impact Assessment……………………………………………. 44

4.3.1 Objectives of EIA Assessment…………………………………….. 44

4.3.2 Impact of the Urea Plant on the environment ……………………… 45

4.3.3 Emissions to Air…………………………………………………… 46

4.3.4 Emissions to Water………………………………………………… 46

4.3.5 Emissions to Land………………………………………………….. 46

4.3.6 Elimination Methods………………………………………………. 47

4.4 Safety Of the Urea Plant……………………………………………………….. 49

4.4.1 Safety factors relevant to urea …………………………………….. 50

4.4.2 Safety Factors Relevant to Ammonia……………………………… 53

4.4.3 Safety Factors Relevant to Ammonium Carbamate ……………… 57

4.4.4 Safety Factors Relevant to Biurete (byproduct)…………………… 60

Chapter 5

5.0 Mass Balance Calculation…………………………………………………….. 64

5.1 Material Balance……………………………………………………………… 64

5.1.1 Reactor…………………………………………………………….. 66

5.1.2 Stripper…………………………………………………………….. 67


5.1.4 Scrubber…………………………………………………………… 69

5.1.5 High Pressure Decomposer………………………………...……… 70

5.1.6 Low Pressure Decomposer ………………………………………… 71


Comprehensive design project VII

5.1.7 Low Pressure Absorber……………………………………………. 72

5.1.8 Medium Pressure Absorber………………………………………… 73

5.1.9 Flash Separator…………………………………………………….. 74

5.1.10 Lower Separator………………………………………………….. 75

5.1.11 Upper Separator…………………………………………………... 76

5.1.12 Waste Water Treatment Unit………………………………….….. 77

5.1.13 Granulator………………………………………………………… 78

5.1.14 Screen……………………………………………………………... 79

5.1.15 Product Cooler……………………………………………………. 80

5.1.16 Bag Filter…………………………………………………………. 81

Chapter 6

Material Flow Sheet……………………………………………………………… 83

Chapter 7

7.0 Heat Balance Calculation……………………………………………………… 85

7.1 Main Process Energy Balance………………………………………………… 85

7.1.1 Reactor…………………………………………………………….. 88

7.1.2 Stripper…………………………………………………………….. 90

7.1.3 Scrubber…………………………………………….……………… 91


7.1.5 High pressure decomposer………………………………………… 95

7.1.6 Low pressure decomposer………………………………………… 96

7.1.7 Low pressure absorber…………………………………………….. 98

7.1.8 High pressure absorber…………………………………………….. 99

7.1.9 Flash separator…………………………………………………….. 101

7.1.10 Lower separator………………………………………………….. 102

7.1.11 Upper separator…………………………………………………... 103

7.1.12 Process wastewater treatment unit……………………………….. 104

7.2 Granulation Plant……………………………………………………………… 105

7.2.1 Granulator…………………………………………………………. 105

7.2.2 Product cooler……………………………………………………... 105

Chapter 8

8.0 Tabulated Heat Balance……………………………………………………….. 107


Comprehensive design project VIII

References ………………………………………………………... 109

List of Figures Page No

Figure 1.1 Chemical structures of urea molecules………………………………… 03

Figure 1.2 (a) The change in world consumption…………………………………. 11

Figure 1.3: Global distribution of the consumption of urea fertilizer…………….. 13

Figure 1.4 Urea import data……………………………………………………..… 16

Figure 2.1 Conventional process flow diagram…………………………………… 23

Figure 2.2 CO2 stripping process flow diagram…………………………………… 26

Figure 3.2 Functional block diagram of the ACES………………………………… 32

Figure 3.1 Process Flow Sheet…………………………………………………….. 32

Figure 3.3 Pipe and Instrumentation diagram……………………………………… 33

Figure 3.4 Granulation plant ……………………………………………………… 37

Figure 3.5 Spout-Fluid Bed Granulator……………………………………………. 37

Figure 3.6 Power Consumption of Spout-Fluid Bed Granulation…………………. 38

Figure 3.7 Various sizes of granules ……………………………………………… 38

Figure 4.1 Plant layout……………………………………………………….……. 43

Figure 6.1 Material Flow Sheet……………………………………………………. 83

List of Tables Page No

Table1.1 chemical characteristics of urea…….…………………………………… 04

Table 1.2 Physical Characteristics of Urea………………………………………… 04

Table 1.3 Urea Prices……………………………………………………………… 15

Table 3.1 ACES Urea plants available in the world Process………………………. 34

Table 4.1 Ammonia releases from urea plants…………………………………….. 45

Table 4.2 Typical consumption figures for a granulation plant…………………… 45

Table 4.3 Emissions from Urea manufacturing process………………………….. 45

Table 5.1 Compound in urea manufacturing………………………………………. 65

Table 8.1 Tabulated Heat Balance………………………………………………… 107

Urea Manufacturing Plant Chapter 01

Comprehensive design project 1

CHAPTER 1

LITERATURE SURVEY



1.0 Literature Survey

1.1 Urea

Urea is an oraganic compound with the chemical formula (NH2)2CO. Urea is also

known by the International Nonproprietary Name (INN) carbamide, as established by the World

Health Organization. Other names include carbamide resin, isourea, carbonyl diamide, and

carbonyldiamine.

1.1.1 Synthetic urea

It was the first organic compound to be artificially synthesized from inorganic

starting materials, in 1828 by Friedrich Wöhler, who prepared it by the reaction of potassium

cyanate with ammonium sulfate. Although Wöhler was attempting to prepare ammonium

cyanate, by forming urea, he inadvertently discredited vitalism, the theory that the chemicals of

living organisms are fundamentally different from inanimate matter, thus starting the discipline

of organic chemistry.

This artificial urea synthesis was mainly relevant to human health because of urea

cycle in human beings. Urea was discovered; synthesis in human liver in order to expel excess

nitrogen from the body. So in past urea was not considered as a chemical for agricultural and

industrial use. Within the 20th

century it was found to be a by far the best nitrogenic fertilizer for

the plants and became widely used as a fertilizer. Urea was the leading nitrogen fertilizer

worldwide in the 1990s.Apart from that urea is being utilized in many other industries.

Urea is produced on a scale of some 100,000,000 tons per year worldwide. For use in

industry, urea is produced from synthetic ammonia and carbon dioxide. Urea can be produced as

prills, granules, flakes, pellets, crystals, and solutions.More than 90% of world production is

destined for use as a fertilizer. Urea has the highest nitrogen content of all solid nitrogenous

fertilizers in common use (46.7%). Therefore, it has the lowest transportation costs per unit of

nitrogen nutrient. Urea is highly soluble in water and is, therefore, also very suitable for use in

fertilizer solutions (in combination with ammonium nitrate).

1.1.2 Commercial production of urea

Urea is commercially produced from two raw materials, ammonia, and carbon

dioxide. Large quantities of carbon dioxide are produced during the manufacture of ammonia

from coal or from hydrocarbons such as natural gas and petroleum-derived raw materials. This

allows direct synthesis of urea from these raw materials. The production of urea from ammonia

and carbon dioxide takes place in an equilibrium reaction, with incomplete conversion of the

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reactants. The various urea processes are characterized by the conditions under which urea

formation takes place and the way in which unconverted reactants are further processed.

Unconverted reactants can be used for the manufacture of other products, for example

ammonium nitrate or sulfate, or they can be recycled for complete conversion to urea in a total-

recycle process. Two principal reactions take place in the formation of urea from ammonia and

carbon dioxide. The first reaction is exothermic:

2 NH3 + CO2 ↔ H2N-COONH4 (ammonium carbamate)

Whereas the second reaction is endothermic:

H2N-COONH4 ↔ (NH2)2CO + H2O

Both reactions combined are exothermic.

1.1.3 Chemical characteristics of urea

The urea molecule is planar and retains its full molecular point symmetry, due to

conjugation of one of each nitrogen's P orbital to the carbonyl double bond. Each carbonyl

oxygen atom accepts four N-H-O hydrogen bonds, a very unusual feature for such a bond type.

This dense (and energetically favorable) hydrogen bond network is probably established at the

cost of efficient molecular packing: The structure is quite open, the ribbons forming tunnels with

square cross-section. Urea is stable under normal conditions.

Figure 1.1 Chemical structures of urea molecules

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IUPAC name Diaminomethanal

Chemical formula (NH2)2CO

Molecular mass 60.07 g/mol (approximate)

Dipole moment 4.56 p/D

pH (100g.L-1 in water, 20ºC) ~9

1.1.4 Physical characteristics of urea

Urea is a white odourless solid. Due to extensive hydrogen bonding with water (up

to six hydrogen bonds may form - two from the oxygen atom and one from each hydrogen) urea

is very soluble.

Density 1.33·10³ kg/m³, solid

Melting point 132.7 °C (406 K) decomposes

Boiling point NA

Solubility in water

108 g/100 ml (20 °C)

167 g/100 ml (40 °C)

251 g/100 ml (60 °C)

400 g/100 ml (80 °C)

733 g/100 ml (100 °C)

Vapour pressure

<0.1 hPa

Bulk density

0.8 kg.m-3

1.1.5 Raw materials of urea manufacturing

1.1.5.1 Ammonia

Ammonia, NH3, is a comparatively stable, colourless gas at ordinary temperatures,

with a boiling point of –33 C. Ammonia gas is lighter than air, with a density of approximately

0.6 times that of air at the same temperature. The characteristic pungent odors of ammonia can

be detected as low as 1-5ppm. Ammonia can be highly toxic to a wide range of organisms. In

humans, the greatest risk is from inhalation of ammonia vapour, with effects including irritation

and corrosive damage to skin, eyes and respiratory tracts. At very high levels, inhalation of

Table1.1 chemical characteristics of urea

Table 1.2 Physical Characteristics of Urea

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ammonia vapour can be fatal. When dissolved in water, elevated levels of ammonia are also

toxic to a wide range of aquatic organisms. Ammonia is highly soluble in water, although

solubility decreases rapidly with increased temperature. Ammonia reacts with water in a

reversible reaction to produce ammonium (NH4)+ and hydroxide (OH)

- ions, as shown in

equation.

Ammonia is a weak base, and at room temperature only about 1 in 200 molecules are

present in the ammonium form (NH4)+. The formation of hydroxide ions in this reaction

increases the pH of the water, forming an alkaline solution. If the hydroxide or ammonium ions

react further with other compounds in the water, more ammonia with react to reestablish the

equilibrium.

NH3 + H2O (NH4)+

+ OH-

While ammonia-air mixtures are flammable when the ammonia content is 16-25% by

volume, these mixtures are quite difficult to ignite. About 85% of the ammonia produced

worldwide is used for nitrogen fertilizers. The remainder is used in various industrial products

including fibers, animal feed, and explosives.

1.1.5.1.1 Ammonia Production

Essentially all the processes employed for ammonia synthesis are variations of the

Haber-Bosch process, developed in Germany from 1904-1913. This process involves the

reaction of hydrogen and nitrogen under high temperatures and pressures with an iron based

catalyst. This process also requires large energy consumption. Ammonia is generally produced at

a few large plants with stream capacities of 1000 tonnes/day or greater. The formation of

ammonia from hydrogen and nitrogen is a reversible reaction, as shown in equation [2]. The

fraction of ammonia in the final gas mixture is dependent on the conditions employed. Unreacted

hydrogen and nitrogen gases separated from the ammonia and are usually recycled. In almost all

modern plants, the ammonia produced is recovered by condensation to give liquid ammonia.

H2 + 3N2 2NH3

The source of nitrogen is always air. Hydrogen can be derived from a number of raw

materials including water, hydrocarbons from crude oil refining, coal, and most commonly

natural gas. Hydrogen rich reformer off-gases from oil refineries have also been used as a source

of hydrogen. Steam reforming is generally employed for the production of hydrogen from these

raw materials. This process also generates carbon dioxide, which can then be used as a raw

material in the production of urea.



Trace impurities in the feed gases, such as sulphur compounds and chlorides, can

have a detrimental effect on the production of ammonia by poisoning the catalysts employed.

The feed gases, therefore, need to be purified prior to use.

1.1.5.1.2 Ammonia storage

Anhydrous ammonia is usually stored as a liquid in refrigerated tanks at –33.3 C and

atmospheric pressure, often in doubled-walled tanks with the capacity for hundreds or thousands

of tonnes. The low temperature is usually maintained by the venting of ammonia gas. The vented

gas is reliquefied for recycling, or absorbed in water to make aqueous ammonia. Relatively small

quantities of anhydrous ammonia are sometimes stored under pressure in spherical vessel at

ambient temperature. Ammonia is corrosive to alloys of copper and zinc and these materials

must never be used in ammonia service. Iron and steel are usually the only metals used in

ammonia storage tanks, piping and fittings.

1.1.5.2 Carbon Dioxide

CO2 is a odourless and colourless gas which contain 0.03% in the atmosphere. It is

emitted as a pollutant from number of industries. CO2 can be obtained from ammonia production

process as a by product.

1.1.6 Applications of urea

1.1.6.1 Agricultural use

More than 90% of world production is destined for use as a fertilizer. Urea is used as

a nitrogen-release fertilizer, as it hydrolyses back to ammonia and carbon dioxide, but its most

common impurity, biuret, must be present at less than 2%, as it impairs plant growth. Urea has

the highest nitrogen content of all solid nitrogeneous fertilizers in common use (46.4%N.) It

therefore has the lowest transportation costs per unit of nitrogen nutrient. In the past decade urea

has surpassed and nearly replaced ammonium nitrate as a fertilizer

In the soil, urea is converted into the ammonium ion form of nitrogen. For most

floras, the ammonium form of nitrogen is just as effective as the nitrate form. The ammonium

form is better retained in the soil by the clay materials than the nitrate form and is therefore less

subject to leaching. Urea is highly soluble in water and is therefore also very suitable for use in

fertilizer solutions, e.g. in “foliar feed‟ fertilizers.

Commercially, fertilizer urea can be purchased as prills or as a granulated material.

In the past, it was usually produced by dropping liquid urea from a "prilling tower" while drying

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the product. The prills formed a smaller and softer substance than other materials commonly

used in fertilizer blends. Today, though, considerable urea is manufactured as granules. Granules

are larger, harder, and more resistant to moisture. As a result, granulated urea has become a more

suitable material for fertilizer blends.

1.1.6.1.1 Advantages of Fertilizer Urea

Urea can be applied to soil as a solid or solution or to certain crops as a foliar spray.

Urea usage involves little or no fire or explosion hazard.

Urea's high analysis, 46% N, helps reduce handling, storage and transportation costs over

other dry N forms.

Urea manufacture releases few pollutants to the environment.

Urea, when properly applied, results in crop yield increases equal to other forms of

nitrogen.

Nitrogen from urea can be lost to the atmosphere if fertilizer urea remains on the soil

surface for extended periods of time during warm weather. The key to the most efficient use of

urea is to incorporate it into the soil during a tillage operation. It may also be blended into the

soil with irrigation water. A rainfall of as little as 0.25 inches is sufficient to blend urea into the

soil to a depth at which ammonia losses will not occur.

Urea breakdown begins as soon as it is applied to the soil. If the soil is totally dry, no

reaction happens. But with the enzyme urease, plus any small amount of soil moisture, urea

normally hydrolizes and converts to ammonium and carbon dioxide. This can occur in 2 to 4

days and happens quicker on high pH soils. Unless it rains, urea must be incorporated during this

time to avoid ammonia loss. Losses might be quite low if the soil temperature is cold. The

chemical reaction is as follows:

CO(NH2)2 + H2O + urease 2NH3 +CO2

1.1.6.1.2 Soil Application and Placement of Urea

The volatility of urea depends to a great extent on soil temperature and soil pH. If

properly applied, urea and fertilizers containing urea are excellent sources of nitrogen for crop

production. After application to the soil, urea undergoes chemical changes and ammonium (NH4

+) ions form. Soil moisture determines how rapidly this conversion takes place.

When a urea particle dissolves, the area around it becomes a zone of high pH and

ammonia concentration. This zone can be quite toxic for a few hours. Seed and seedling roots

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within this zone can be killed by the free ammonia that has formed. Fortunately, this toxic zone

becomes neutralized in most soils as the ammonia converts to ammonium. Usually it's just a few

days before plants can effectively use the nitrogen. Although urea imparts an alkaline reaction

when first applied to the soil, the net effect is to produce an acid reaction.

Urea or materials containing urea should, in general, be broadcast and immediately

incorporated into the soil. Urea-based fertilizer applied in a band should be separated from the

seed by at least two inches of soil.

1.1.6.1.3 Spreading of Urea

Urea can be bulk-spread, either alone or blended with most other fertilizers. Urea

often has a lower density than other fertilizers with which it is blended. This lack of "weight"

produces a shorter "distance-of-throw" when the fertilizer is applied with spinner-type

equipment. In extreme cases this will result in uneven crop growth and "wavy" or "streaky"

fields.

Urea and fertilizers containing urea can be blended quite readily with

monoammonium phosphate (11-52-0) or diammonium phosphate (18-46-0). Urea should not be

blended with superphosphates unless applied shortly after mixing. Urea will react with

superphosphates, releasing water molecules and resulting in a damp material which is difficult to

store and apply.

Urea fertilizer can be coated with certain materials, such as sulfur, to reduce the rate

at which the nitrogen becomes available to plants. Under certain conditions these slow-release

materials result in more efficient use by growing plants. Urea in a slow-release form is popular

for use on golf courses, parks, and other special lawn situations.

1.1.6.2 Industrial use

Urea has the ability to form 'loose compounds', called clathrates, with many organic

compounds. The organic compounds are held in channels formed by interpenetrating helices

comprising of hydrogen-bonded urea molecules. This behaviour can be used to separate

mixtures, and has been used in the production of aviation fuel and lubricating oils. As the helices

are interconnected, all helices in a crystal must have the same 'handedness'. This is determined

when the crystal is nucleated and can thus be forced by seeding. This property has been used to

separate racemic mixtures.

1.1.6.3 Further commercial uses

A stabilizer in nitrocellulose explosives

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A reactant in the NOx-reducing SNCR and SCR reactions in exhaust gases from

combustion, for example, from power plants and diesel engines

A component of fertilizer and animal feed, providing a relatively cheap source of

nitrogen to promote growth

A raw material for the manufacture of plastics, to be specific, urea-formaldehyde resin

A raw material for the manufacture of various glues (urea-formaldehyde or urea-

melamine-formaldehyde); the latter is waterproof and is used for marine plywood

An alternative to rock salt in the de-icing of roadways and runways; it does not promote

metal corrosion to the extent that salt does

An additive ingredient in cigarettes, designed to enhance flavour

A browning agent in factory-produced pretzels

An ingredient in some hair conditioners, facial cleansers, bath oils, and lotions

A reactant in some ready-to-use cold compresses for first-aid use, due to the endothermic

reaction it creates when mixed with water

A cloud seeding agent, along with salts, to expedite the condensation of water in clouds,

producing precipitation

An ingredient used in the past to separate paraffins, due to the ability of urea to form

clathrates (also called host-guest complexes, inclusion compounds, and adducts)

A flame-proofing agent (commonly used in dry chemical fire extinguishers as Urea-

potassium bicarbonate)

An ingredient in many tooth whitening products

A cream to soften the skin, especially cracked skin on the bottom of one's feet

An ingredient in dish soap.

To make potassium cyanate

A melt agent used in re-surfacing snowboarding halfpipes and terrain park features

A raw material for melamine production More than 95% of all melamine production is

based on urea. Stamicarbon‟s parent company DSM is the largest melamine producer in

the world.

A supplementary substitute protein source in feedstuffs for cattle and other ruminants.

Because of the activity of micro-organisms in their cud, ruminants are able to metabolize

certain nitrogen containing compounds, including urea, as protein substitutes. In the USA

this capability is exploited on a large scale. Western Europe, in contrast, uses little urea in

cattle feed.

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Feed for hydrolyzation into ammonia which in turn is used to reduce emissions from

power plants and combustion engines.

Other, miscellaneous products such as de-icing material for airport runways. Although on

a smaller scale than as a fertilizer or as raw material for synthetic resins, urea is also used

as a raw material or auxiliary material in the pharmaceutical industry, the fermenting and

rewing industries and in the petroleum industry.

1.1.6.4 Laboratory use

Urea is a powerful protein denaturant. This property can be exploited to increase the

solubility of some proteins. For this application, it is used in concentrations up to 10 M. Urea is

used to effectively disrupt the noncovalent bonds in proteins. Urea is an ingredient in the

synthesis of urea nitrate. Urea nitrate is also a high explosive very similar to ammonium nitrate,

however it may even be more powerful because of its complexity.

1.1.6.5 Medical use

1.1.6.5.1 Drug use

Urea is used in topical dermatological products to promote rehydration of the skin. If

covered by an occlusive dressing, 40% urea preparations may also be used for nonsurgical

debridement of nails. This drug is also used as an earwax removal aid. Like saline, urea injection

is used to perform abortions. It is also the main component of an alternative medicinal treatment

referred to as urine therapy.

1.1.6.5.2 Diagnostic use

Isotopically-labeled urea (carbon-14 - radioactive, or carbon-13 - stable isotope) is used

in the urea breath test, which is used to detect the presence of the bacteria Helicobacter pylori

(H. pylori) in the stomach and duodenum of humans. The test detects the characteristic enzyme

urease, produced by H. pylori, by a reaction that produces ammonia from urea. This increases the

pH (reduces acidity) of the stomach environment around the bacteria. Similar bacteria species to

H. pylori can be identified by the same test in animals such as apes, dogs, and cats .

1.1.6.6 Textile use

Urea is a raw material for urea-formaldehyde resins production in the adhesives and

textile industries. A significant portion of urea production is used in the preparation of urea-

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formaldehyde resins. These synthetic resins are used in the manufacture of adhesives, moulding

powders, varnishes and foams. They are also used for impregnating paper, textiles and leather. In

textile laboratories they are frequently used both in dyeing and printing as an important auxiliary,

which provides solubility to the bath and retains some moisture required for the dyeing or

printing process.

1.2 Global production and consumption of Urea

Commercial urea production began in the 1920s with the development of the Haber-Bosch

process.

Figure 1.2 (a) The change in world consumption (million metric tons of N) of total synthetic

nitrogen fertilizers (solid line) and urea consumption (solid bars) since 1960. Data for 2005–

2020 (shown as the shaded region) are calculated assuming an annual increase of 3% in total

consumption and 5% in the fraction that is urea. (b) Same data as in panel (a) with the fraction

that is urea displayed as a percentage of the total nitrogen fertilizer.

Urea is processed into granules or other forms. Urea production is energy intensive.

Most commonly, it is produced using natural gas, so the major producing regions are those

where natural gas is abundant. Several leading manufacturing countries for urea are Russia,

Canada, and Saudi Arabia, but other Middle East producers, including Iran and Iraq are (or were

before the Gulf Wars) significant. In the US, urea production facilities are located mainly in the

Gulf of Mexico states.



Production of urea has at least doubled every decade since 1980 in the Middle East,

increasing from 2 million metric tons per year in 1980 to 10 million metric tons year per in 2000.

Further expansion of production is anticipated in the coming years in Kuwait, Qatar, Egypt,

Oman and Iran. From the mid-1970s to the early 1990s, Russia (USSR) erected at least 40 new

ammonia and urea production facilities. Production of urea in China tripled from 1989 to 1999.

Dramatic increases in global production have also occurred in many countries since 2000, with

several Latin American countries increasing production by more than 25%. As late as the 1960s,

urea represented only about 5% of world nitrogen fertilizer use. However, urea usage escalated

in the 1980s, such that it represented about 40% of global nitrogen fertilizer by the early 1990s,

and soon thereafter urea surpassed ammonium nitrate as the most common nitrogen fertilizer. It

is now estimated that urea represents >50% of world nitrogen fertilizer (Figure 1b).

Assuming urea consumption continues at 5% per year, as projected for many parts of

the world, urea consumption may reach 70% of total nitrogen use by the end of the next decade

(Figure 1b): this is a dramatic global change in the composition of nitrogen applied to land

throughout the globe. Such projections depend on global commodity markets, construction of

new plants, and other factors that are difficult to project, but most of this increase is expected to

occur in developing countries, particularly in Asia and Latin America. China and India together

account for about half of the global consumption, and have at least doubled their consumption of

urea in the past decade. In India, Bangladesh and Pakistan, urea fertilizer has been heavily

subsidized (as much as 50% of the cost of production) leading to its widespread use and over-

application.

The US and Canada now represent about 20% of the global urea market, with urea

constituting about 30% of US synthetic nitrogen fertilizer usage. Consumption is increasing even

in regions where land applications of nitrogen have heretofore been low. The rural Canadian

provinces of Manitoba, Saskatchewan and Alberta, for example, are now the regions where over

70% of Canada‟s urea is consumed. Urea is the only form of fertilizer used in British Columbia

forests. In Latin America, consumption of urea has fluctuated more than in Asia during the past

decade due to various economic crises and unstable political environments, leading to fluctuating

incentives and subsidies.

This global trend in increased urea consumption represents both a net increase in

total nitrogen applied, as well as a shift from the use of nitrate or anhydrous ammonium to urea.

These increases parallel the increases in the production of both cereal and meat (associated with

increasing human population) that have occurred globally in the past several decades. Urea is

used in the production of virtually all crops from corn to Christmas trees, sugar cane to sweet



potatoes, and vegetables to vineyards. Urea is preferable to nitrate for growing rice in flooded

soils, and thus the Far East and the Mid-East are major consumers of urea. In coated form, urea

becomes a slow-release fertilizer and this is one of the most popular forms for applications to

lawns, golf courses, and parks, as well as many crops.

The global shift toward the use of urea fertilizer stems from several advantages it has

over other fertilizer forms. It is less explosive than ammonium and nitrate when stored, it can be

applied as a liquid or solid, and it is more stable and cost effective to transport than other forms

of reactive nitrogen. The increasing production of „granular‟ urea has contributed to its

widespread use, as this is safe and easy to transport. Urea also contains twice the nitrogen of

ammonium sulfate, making application rates per unit of fertilizer less costly for individual

farmers. With the growth of large, industrial farms, the economics and safety of urea transport

and storage are thus major factors in the shift away from ammonium nitrate.

Figure 1.3: Global distribution of the consumption of urea fertilizer, in metric tons per year by

country, in 1960 (upper panel) and in 1999 (lower panel), based on data from the Global

Fertilizer Industry data base (FAO 2001),These estimates of urea consumption do not include

uses other than fertilizer.



1.2.1 Range of global uses of urea

While more than 75% of manufactured urea is consumed as nitrogen fertilizer, there

are other significant uses of urea, which also are increasing globally. One such use is as a feed

additive for ruminants, used to stimulate gut microbial flora. This application represents about

10% of non-fertilizer usage. Urea can be added directly to feed, such as in urea-treated wheat or

rice straw, or mixed with molasses („urea–molasses licks‟ or „urea multi-nutrient blocks‟) for

sheep, cattle, water buffalo, and horses. Urea may also be used as a fertilizer of the grasslands on

which cattle or sheep may graze.

Another direct application of urea to land is as urea-based herbicides or pesticides

(sulfonyl urea pesticides). In this case, urea is chemically synthesized with a poison or inhibitor.

Sulfonyl urea is one of the preferred herbicides for broadleaf and grassy weeds. It is also

commonly used in non-agricultural situations, such as to control weeds in railroad and electric

utility rights of way. Urea-based herbicides potentially have a large impact by both increasing

urea inputs and reducing the potential for local uptake. Urea has long been used as a de-icer.

Commercial airports and airfields are the largest consumers of these de-icing materials, although

recommendations are now in place to reduce its usage in the US and elsewhere because of its

recognized contribution to water pollution. Even with such reductions, it is still the de-icer of

choice under some weather conditions. It is also used fairly extensively for domestic ice-melting

applications (e.g. roads and sidewalks). Urea may also be spread on agricultural crops to prevent

frost when temperatures drop to a level that may cause crop damage, and commercial

formulations of urea are available for this purpose.

Urea is also used in some direct applications to seawater. It is used in the growing

world aquaculture industry. In intensive shrimp culture, for example, ponds may be fertilized

with urea and superphosphate to initiate an algal bloom that eventually serves as food for the

commercial resource. A significant proportion of such nutrients are subsequently discharged to

local waters with pond effluent, as only a small fraction of added nutrients ultimately winds up in

marketable product.

Urea may also be spread on coastal oil spills, to stimulate the growth of natural

bacteria populations which break down the oil; it was widely used, for example, during the

Exxon Valdez spill, and has been used in numerous other spills since. For the Exxon Valdez

spill, fertilizer applications continued for years following the initial crisis, and this approach was

estimated to have enhanced the degradation of the oil by 2–5-fold.



In addition to the direct applications of urea to land and sea, urea is used in many

other applications, including manufacture of a wide range of common materials such as urea

formaldehyde and plastics. This use represents about 50% of the non-fertilizer urea. Urea is also

an additive in fire retardant paints, tobacco products, and in some wines. In the cosmetics

industry, urea is an ingredient in moisturizing creams. There are numerous uses of urea in

holistic medicine therapies. One application currently being considered which would greatly

expand the global use of urea is as a reductant in catalytic and non-catalytic reduction of

combustion products in vehicles.

1.3 Urea Prices

The world price for urea has trended downwards in real terms since 1975, although it can

be volatile. In real terms (1990s), the price per ton was $438 in 1975; $309 in 1980; $199 in

1985, and $131 in 1990. These prices are on a bulk FOB basis, and freight and bagging charges

of about $20 to $25 per ton must be added to arrive at bagged import costs. From 1991 to 2000,

the prices of urea ($/ton) are shown in the table below:

year 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 Mean

Urea

($/ton)

$151 $123 $ 94 $131 $194 $187 $128 $103 $ 78 $112 $130

Source: IMF, International Financial Statistics, Yearbook and July, 2001 issues.

Table 2.3 Urea Prices

1.4 Urea Production and Consumption in Sri Lanka

In Sri Lanka urea is being used as a fertilizer in the agriculture sector. Other than as

a fertilizer, urea is hardly used in any industry or any other sector even though urea has number

of industrial and commercial uses.

Sri Lanka imports urea from other countries such as Saudi Arabia, India, and China. .

The total import volume of urea is around 330,000 MT per annum. Sri Lankan government gives

urea fertilizer in subsidized price for farmers. From the budget 2008, Sri Lanka allocated 15

billion rupees for fertilizer subsidies.

However in the past with the Urea Plant at Sapugaskanda, Sri Lanka was able to

became self sufficient in fertilizer requirements of the country. In 1982, the annual production of

urea at Sapugaskanda factory was 310,000 tons. Then the country's annual demand was only

290,000 tons. The excessive production of 20,000 tons of urea was exported earning foreign

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UREA IMPORTS

0

2000

4000

6000

8000

10000

12000

14000

1997 1999 2000 2001 2002 2004 2005 2006 2007

Year

To

tal

Co

st

in R

s M

illi

on

s

TOTAL UREA IMPORTS

0

50000

100000

150000

200000

250000

300000

350000

1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007

Year

Qu

an

tity

(M

T)

exchange around Rs. 200 million. In 1982 the annual savings of State Fertilizer Corporation

stood at Rs.750 million. Urea plant was closed in January 1987.

According to the Sri Lanka Custom data records, following graphs shows total urea

imports to the country within past 10 years and relative costs involved.

With the development in agriculture sector under present government policies and

considering global food crisis, urea demand will further increase in spite there is a concern to use

organic fertilizers such as compost instead of urea. Urea is being used as the main fertilizer for

paddy as well as for other crops. Excessive applying of urea without considering the requirement

has damage water bodies in some part of Sri Lanka.

Figure 1.4 Urea import data

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CHAPTER 2

PROCESS SELECTION AND

ECONOMIC ASPECTS



2.0 Process Selection & Economic Aspects

2.1 Feasibility Study

2.1.1 Introduction

Urea white crystalline solid containing 46% nitrogen is widely used in the agriculture

industry as an animal feed additive and fertilizer. Agriculture forms the major sector in the

national economy of the majority of the countries in the Southeast Asian region. As these

countries try to expand the sector, through diversification of agriculture and extensive multiple

cropping programs, the demand for agriculture chemicals growing day by day.

Large population countries like China, India, Pakistan, and Bangladesh are largely

manufacturing the Urea for Domestic consumption. Due to high cost of the production facility

Government incentives are common in 3rd

world countries. In Middle East Saudi Arabia

developed the large production facility of Urea production as an allied industry of the petroleum

product. The surplus amount is being exported to neighboring countries.

Sri Lanka imports urea from other countries such as Saudi Arabia, India, and China. .

The total import volume of urea is around 310,000 MT per annum. Sri Lankan government gives

urea fertilizer in subsidized price for farmers. From the budget 2008, Sri Lanka allocated 15

billion rupees for fertilizer subsidies.

The Urea Plant at Sapugaskanda, Sri Lanka was established in 1980s to fulfil

fertilizer requirement of the country. In 1982, the annual production of urea at Sapugaskanda

factory was 310,000 tons. Then the country's annual demand was only 290,000 tons. The

excessive production of 20,000 tons of urea was exported earning foreign exchange around Rs.

200 million. In 1982 the annual savings of State Fertilizer Corporation stood at Rs.750 million.

In addition it had provided direct employment opportunities to 1,250 workers. So the previous

plant is Sapugaskanda had been able to gain profits while making Sri Lanka self sufficient in

urea.

In the present urea fertilizer prices in global markets are increasing and most

countries establishing urea manufacturing plants to support growing agriculture sector while

saving cost of urea fertilizer imports. It is necessary to establish urea manufacturing plant in Sri

Lanka in order to meet growing demand for urea fertilizer and to save fertilizer subsidies given

by the government. Apart from those benefits it can earn foreign exchange by exporting excess

production and provide employment for local community.

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2.1.2 Technical & Economic Feasibility

When considering economic feasibility, raw material cost could be higher than usual

since all most all urea manufacturing plants is being operated along with ammonia plants in

order to produce raw materials (Ammonia and carbon dioxide: The carbon is produced as a bye-

product from the ammonia plant) for urea manufacturing process.

To establish a urea plant without ammonia plant, raw materials has to be imported. It

is not a better option, but under the circumstances Ammonia has to be imported from abroad.

Considering the carbon dioxide, it is emitted by number of industries as a waste from which it

has to be derived and purify. If it is not viable it is too has to be imported. Transportation cost

will quite high (shipping costs, import taxes etc) so imported raw materials will be higher than

when produced in ammonia plant.

Plant technology is considered as high. Japan, China and North European countries

are licensing the technology. Government incentives can be obtained for construction and

operation since high costs are involved.

The plant can be ordered directly from the manufacturers which basically sell the

license of technology. Local fabrication can be carried out. Where as more critical equipments

can be imported. Latest technology for confirming the quality and purity of the finished good is

very important to complete the existing units.

Companies involve in urea manufacturing technology and have license for technology.

1. Toyo Engineering corporation ( Japan )

2. Mitsubishi Heavy industries ( Japan )

2.1.2.1 Plant Capacity

Urea plant capacity is on the rise since its establishment in 1940. In 1969 1800

MT/day plant was the largest. In Nineties 2000 tons urea plants become standardized. Now up to

3500 tons/day plants are under construction and planning.

In this project we are planning to establish 1070 Mt/day plant having overall annual

production of 350,000 MT. Plant is expected to operate 328 days per annum. Current Sri Lankan

annual demand for urea is around 310,000 and it is not expected to fluctuate very much

according to the statistical data obtained for past ten years. So Plant capacity is sufficient for

meeting the current demand as well as growing demand in the future.

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2.1.3 Social & Environmental Feasibility

Environmental feasibility is discussed under environmental impact assessment (EIA) and in site

selection. Social issues are considered under site selection.

2.1.4 Plant Components

The components of a urea plant can be divided in to two categories

1. Static Equipment

2. Rotating equipment

Static Equipment

Reactor:

Reactor is the largest and heaviest key equipment in the urea plant. This is the place

where Ammonia and Carbon di-oxide react together. The performance of the reactor influences

the performance of the whole urea plant.

The size of the shell depends upon the size of plant. For a plant of 2000 tons capacity the height

of the shell will be around 30 Meters and Dia around 3 meters.

Stripper

Stripper is also a key component where the excess ammonia is separated.

Carbamate Condensers

They are relatively smaller in size

HP Rotating Machines

CO2 Compressors

This is the largest and most critical rotating equipment. Very large compressors are used of

approximate capacities of around 30,000 N cubic meter/hour capacity

HP Ammonia pumps and Carbomate pumps piping

Stainless steel 316 L pipes are utilized

HP Control Valves

Various control valves are required. The most critical is the solution feed control valve from the

reactor to stripper. The material is stainless steel

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2.2 Process Selection

Several processes are used to urea manufacturing. Some of them are used

conventional technologies and others use modern technologies to achieve high efficiency. These

processes have several comparable advantages and disadvantages based on capital cost,

maintenance cost, energy cost, efficiency and product quality. Some of the widely used urea

production processes are

1. Conventional processes

2. Stamicarbon CO2 – stripping process

3. Snamprogetti Ammonia and self stripping processes

4. Isobaric double recycle process

5. ACES process

2.2.1 Conventional Processes

2.2.1.1 Once through Process

In this process non converted ammonia was neutralized with acid such as nitric acid

to produce ammonium salt such as ammonium nitrate as co products of urea production. In this

way, a relatively simple urea process scheme was realized. The main disadvantages of this

process are the large quantity of ammonia salt formed as co product and the limited amount of

overall carbon dioxide conversion that can be achieved.

2.2.1.2 Conventional Recycle Process

Here all of the non converted ammonia and carbon dioxide were recycled to the urea

reactor. In first generation of this process the recirculation of non converted NH3 and CO2 was

performed in two stage. The first recirculation was operated at medium pressure (18-25 bar); the

second at low pressure (2-5 bar). The first recirculation comprises at least a decomposition

heater, in which carbamate decompose into gaseous NH3 and CO2, and while excess NH3

evaporate simultaneously. The off gas from this first decomposition step was subjected to

rectification, from which relatively pure ammonia at the top and a bottom product consisting of

an aqueous ammonium carbamate solution were obtained. Both products are recycled separately

to the urea reactor. In these processes, all non converted CO2 was recycled as associated water

recycle. Because of the detrimental effect of water on reaction conversion, achieving a minimum

CO2 recycle so achieve maximum CO2 conversion was more important than achieving a low

NH3 recycle. All conventional processes therefore typically operate at high NH3:CO2 ratios (4-5

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mol/mol) to maximize CO2 conversion per pass. Although some of these conventional processes

partly equipped with ingenious heat exchanging net works have survived until now. Their

importance decreased rapidly as the so-called stripping process was developed.



Figure 2.1 Conventional process flow diagram



2.2.2 Stamicarbon CO2 – stripping process

In this process to achieve maximum urea yield per pass through the reactor at the

stipulated optimum pressure of 140 bar, an NH3:CO2 molar ratio of 3:1 is applied. The greater

part of the unconverted carbamate is decomposed in the stripper, where ammonia and carbon

dioxide are stripped off. This stripping action is effected by countercurrent contact between the

urea solution and fresh carbon dioxide at synthesis pressure. Low ammonia and carbon dioxide

concentration in the stripped urea solution are obtained. Such that the recycle from the low

pressure recirculation stage is minimized. These low concentration of both ammonia and carbon

dioxide in the stripper effluent can be obtained at relatively low temperatures of the urea solution

because carbon dioxide is only sparingly soluble under such conditions.

Condensation of ammonia and carbon dioxide gases, leaving the stripper, occurs in

the high pressure carbamate condenser as synthesis pressure. As a result, the heat liberated from

ammonium carbamate formation is at a high temperature. This heat is used for the production of

4.5bar steam for use in the urea plant itself. The condensation in the high pressure carbamate

condenser is not effected completely. Remaining gases are condensed in the reactor and provide

the heat required for the dehydration of carbamate, as well as for heating the mixture to its

equilibrium temperature. In recent improvement to this process, the condensation of off gas from

the stripper is carried out in a pre reactor, where sufficient residence time for the liquid phase is

provided. As a result of urea and water formation in condensing zone, the condensation

temperature is increased, thus enabling the production of steam at higher pressure level.

The feed carbon dioxide, invariably originating from an associated ammonia plant,

always contains hydrogen. To avoid the formation of explosive hydrogen-oxygen mixture in the

tail gas of the plant, hydrogen is catalytically removed from the CO2 feed. Apart from the air

required for this purpose, additional air is supplied to the fresh CO2 input stream. This extra

potion of oxygen is needed to maintain a corrosion-resistance layer on the stainless steel in the

synthesis section. Before the inert gases, mainly oxygen and nitrogen, are purged from the

synthesis section, they are washed with carbamate solution from the low pressure recirculation

stage in the high pressure scrubber to obtain a low ammonia concentration in the subsequently

purged gas. Further washing of the off gas is performed in a low pressure absorber to obtain a

purge gas that is practically ammonia free. Only one low pressure recirculation stage is required

due to the low ammonia and carbon dioxide in the stripped urea solution. Because of the ideal

ratio between ammonia and carbon dioxide in the recovered gases in this section, water dilution

of the resultant ammonium carbamate is at a minimum despite the low pressure (about 4 bar). As

a result of efficiency of the stripper, the quantities of ammonium carbamate for recycle to the



synthesis section are also minimized, and no separate ammonia recycle is required.

The urea solution coming from the recirculation stage contains about 75 wt% urea.

This solution is concentrated in the evaporation section. If the process is combined with a

prilling tower for final product shaping, the final moisture content of urea from the evaporation

section is 0.25 wt%. If the process is combined with a granular unit, the final moisture content

may wary from 1 to 5 wt%, depending on granulation requirements. Higher moisture content can

be realized in a single stage evaporator; where as low moisture content are economically

achieved in a two stage evaporation section.

When urea with an extremely low biuret content is required ( at maximum of 0.3

wt%) pure urea crystals are produced in a crystallization section. These crystals are separated

from the mother liquor by combination of sieve bends and centrifuges and are melted prior to

final shaping in a prilling tower or granulation unit.

The process condensate emanating from water evaporation from the evaporation or

crystallization sections contains ammonia and urea. Before this process condensate is purged,

urea is hydrolyzed into ammonia and carbon dioxide, which are stripped off with steam and

return to urea synthesis via the recirculation section. This process condensate treatment section

can produce water with high purity, thus transforming this “waste water” treatment into the

production unit of a valuable process condensate, suitable for, e.g., cooling tower or boiler feed

water makeup. Since the introduction of the Stamicarbon CO2 stripping process, some 125 units

have been built according to this process all over the world.



Figure 2.2 CO2 stripping process flow diagram



2.2.3 Snamprogetti Ammonia and self stripping processes

In the first generation of NH3 and self strip ping processes, ammonia was used as

stripping agent. Because of the extreme solubility of ammonia in the urea containing synthesis

fluid, the stripper effluent contained rather large amount s of dissolved ammonia, causing

ammonia overload in down stream section of the plant. Later versions of the process abandoned

the idea of using ammonia as stripping agent; stripping was achieved only by supply of heat.

Even without using ammonia as a stripping agent, the NH3:CO2 ratio in the stripper effluent is

relatively high. So the recirculation section of the plant requires an ammonia-carbomate

separation section

The process uses a vertical layout in the synthesis section. Recycle within the

synthesis section, from the stripper via the high pressure carbamate condenser, through the

carbamate separator back to the reactor, is maintained by using an ammonia-driven liquid-liquid

ejector. In the reactor, which is operated at 150 bars, NH3:CO2 molar feed ratio of 3.5 is applied.

The stripper is of the falling film type. Since stripping is achieved thermally, relatively high

temperatures (200-210 0C) are required to obtain a reasonable stripping efficiency. Because of

this high temperature, stainless steel is not suitable as a construction material for the stripper

from a corrosion point of view; titanium and bimetallic zircornium – stainless steel tubes have

been used

Off gas from the stripper is condensed in a kettle type boiler. At the tube side of this

condenser the off gas is absorbed in recycled liquid carbamate from the medium pressure

recovery section. The heat of absorption is removed through the tubes, which are cooled by the

production of low pressure steam at the shell side. The steam produced is used effectively in the

back end of the process.

In the medium pressure decomposition and recirculation section , typically operated

at 18 bar, the urea solution from the high pressure stripper is subjected to the decomposition of

carbamate and evaporation of ammonia. The off gas from this medium pressure decomposer is

rectified. Liquid ammonia reflux is applied to the top of this rectifier; in this way a top product

consisting of pure gaseous ammonia and a bottom product of liquid ammonium carbamate are

obtained. The pure ammonia off gas is condensed and recycled to the synthesis section. To

prevent solidification of ammonium carbamate in the rectifier, some water is added to the bottom

section of the column to dilute the ammonium carbamate below its crystallization point. The

liquid ammonium carbamate-water mixture obtained in this way is also recycled to the synthesis

section. The purge gas of the ammonia condenser is treated in a scrubber prior to being purged to

the atmosphere.



The urea solution from the medium pressure decomposer is subjected to a second

low pressure decomposition step. Here further decomposition of ammonium carbamate is

achieved, so that a substantially carbamate –free aqueous urea solution is obtained. Off gas from

this low pressure decomposer is condensed and recycled as an aqueous ammonium carbamate

solution to the synthesis section via the medium pressure recovery section.

Concentrating the urea water mixture obtained from the low pressure decomposer is

preformed in a single or double evaporator depending on the requirement of the finishing

section. Typically, if prilling is chosen as the final shaping procedure, a two stage evaporator is

required, whereas in the case of a fluidized bed granulator a single evaporation step is sufficient

to achieve the required final moisture content of the urea melt. In some versions of the process,

heat exchange is applied between the off gas from the medium pressure decomposer and the

aqueous urea solution to the evaporation section. In this way, the consumption of low pressure

steam by the process is reduced.

The process condensate obtained from the evaporation section is subjected to a

desorption hydrolysis operation to recover the urea and ammonia contained in the process

condensate.

2.2.4 Isobaric double recycle process

This process is developed by Montedison, is characterized by recycle of most of the

un reacted ammonia and ammonium carbamate in two decomposer in series, both operating at

the synthesis pressure. A high molar NH3:CO2 ratio (4:1 to 5:1) in the reactor is applied. As a

result of this choice ratio, the reactor effluent contains a relatively high amount of non converted

ammonia. In the first, steam heated, high pressure decomposer, this large quantity of free

ammonia is mainly removed from the urea solution. Most of the residual solution, as well as

some ammonium carbamate, is removed in the second high pressure decomposer where steam

heating and CO2 stripping are applied. The high pressure synthesis section is followed by two

low pressure decomposing stages of traditional design, where heat exchange between the

condensing off gas of the medium pressure decomposition stage and the aqueous urea solution to

the final concentration section improves the overall energy consumption of the process. Probably

because of the complexity of this process, it has not achieved great popularity so far. This

process or parts of the process are used in four revamps of older conventional plant.



2.2.5 ACES process

ACSE (Advanced Process for Cost and Energy Saving) process has been developed

by Toyo Engineering Corporation. Its synthesis section consist of the reactor, stripper, two

parallel carbamate condensers and a scrubber all operated at 175 bar.

The reactor is operated at 1900C and an NH3:CO2 molar feed ratio of 4:1. Liquid

ammonia is fed directly to the reactor, whereas gaseous carbon dioxide after compression is

introduced into the bottom of the stripper as a stripping aid. The synthesis mixture from the

reactor, consisting of urea, unconverted ammonium carbamate, excess ammonia, and water, is

fed to the top of the stripper.

2.2.6 Process comparison .

Process Advantages Disadvantages

Conventional Processes -

Once through process

Simple process Large quantity of

ammonia salt is formed as

co product

Overall carbon dioxide

conversion is low.

High production cost

High energy cost

High environment

pollution

Conventional Processes

–

Conventional recycle

process

High CO2 conversion High production cost

High energy cost

High environment

pollution

Stamicarbon CO2 –

stripping process

Has high urea yield per

pass

High purity


High energy cost

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Snamprogetti Ammonia

and self stripping

processes

Low consumption of low

pressure steam


High energy cost

Isobaric double recycle

process

Complex process

ACES process Low production cost

High energy recovery

Low environment

pollution

High efficiency

High capital cost

Among above urea manufacturing processes, ACES process is selected because of it has

following advantages compared to other processes

2.2.6.1 Advantages of ACES Process

Less HP piping and construction materials owing to lower elevation layout, fewer HP

vessels and simplified synthesis loop

Easier erection using commonly available construction equipment and techniques owing

to low elevation layout and fewer and smaller HP vessels

Easier operation supported by forced circulation by HP ejector, low elevation layout and

fewer HP equipment

Easier maintenance owing to low elevation layout and fewer HP equipment

Less energy consumption owing to optimized synthesis conditions and proprietarily

designed reactor and stripper

Even though initial capital investment is higher than the other processes, it will

overcome by lower production cost per metric ton of urea

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CHAPTER 3

PROCESS DESCRIPTION AND

FLOW SHEET



3.0 Process Description and flow sheet

3.1 Process Description – ACES Process

Advanced Process for Cost and Energy process consists of the reactor, stripper, two

parallel carbamate condensers and a scrubber. All above equipments are operated at 175 bar.

Figure 3.1 Functional block diagram of the ACES

Process

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The reactor is operated at 1900C and an NH3:CO2 molar feed ratio of 4:1. Liquid

ammonia is fed directly to the reactor, whereas gaseous carbon dioxide after compression is

introduced into the bottom of the stripper as a stripping aid. The synthesis mixture from the

reactor, consisting of urea, unconverted ammonium carbamate, excess ammonia, and water, is

fed to the top of the stripper. The stripper has two functions. Its upper part is equipped with trays

where excess ammonia is partly separated from the stripper feed by direct countercurrent contact

of the feed solution with the gas coming from the lower part of the stripper. This pre stripping in

the top is said to be required to achieve effective CO2 stripping in the lower part. In the lower

part of the stripper (a falling film heater), ammonium carbamate is decomposed and the resulting

CO2 and NH3 as well as the excess NH3 are evaporated by CO2 stripping and steam heating. The

overhead gaseous mixture from the top of the stripper is introduced into the carbamate

condenser. Here the gaseous mixture is condensed and absorbed by the carbamate solution

coming from the medium pressure recovery stage. Heat liberated in the high pressure carbamate

condenser is used to generate low pressure steam. The gas and liquid from the carbamate

condensers are recycled to the reactor by gravity flow. The urea solution from the stripper, with a

typical NH3 content of 15 wt%, is purified further in the subsequent medium and low pressure

decomposers, operating at 17.5 and 2.5 bars, respectively. Ammonia and carbon dioxide

separated from the urea solution here are recovered through stepwise absorption in the low and

medium pressure absorbers. Condensation heat in the medium pressure absorber is transferred

directly to the aqueous urea solution feed in the final concentration section; the purified urea

solution is concentrated further either by two stage evaporation up to 99.7 % for urea prill

production or by a single evaporation 98.5 % for urea granule production. Water vapour formed

in the final concentrating section is condensed in surface condensers to form process condensate.

Part of this condensate is used as an absorbent in the recovery sections, where as remainder is

purified in the process condensate treatment section by hydrolysis and steam stripping, before

being discharge from the urea plant.

The highly concentrated urea solution is finally processed either through the prilling

tower or via the urea granulator. Instead of concentration via evaporation, the ACES process can

also be combined with a crystallization section to produce urea with low biuret content.



3.1.1ACES Urea plants available in the world

3.2 Main component of the process

3.2.1 Reactor

The reactor is operated at 190 °C and 175 bar. NH3:CO2 molar feed ratio to the

reactor is 4:1. One pass conversion rate of CO2 to urea is about 68%. NH3 is directly fed to the

reactor. Following reaction occurs inside the reactor.

NH2COONH4 + heat ↔ NH2CONH2 + H2O ∆H = +23 kJ/mol

2NH3 + CO2 ↔ NH2COONH4 + heat ∆H = -84 kJ/mol

3.2.2 Stripper

Carbon dioxide is introduced into the bottom of the stripper as a stripping aid. The

synthesis mixture from the reactor, consisting of urea, unconverted ammonium carbamate,

excess ammonia, and water, is fed to the top of the stripper. Medium pressure steam is supplied

to the stripper. The stripper has two functions. Its upper part is equipped with trays where excess

ammonia is partly separated from the stripper feed by direct countercurrent contact of the feed

solution with the gas coming from the lower part of the stripper. This pre stripping in the top is

said to be required to achieve effective CO2 stripping in the lower part. In the lower part of the

stripper (a falling film heater), ammonium carbamate is decomposed and the resulting CO2 and

NH3 as well as the excess NH3 are evaporated by CO2 stripping and steam heating. The overhead

gaseous mixture from the top of the stripper is introduced into the carbamate condenser.

Following reaction occurs inside the stripper.

Table 3.1 ACES Urea plants available in the world Process

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NH2COONH4 + heat ↔ 2NH3 + CO2 ∆H = +84 kJ/mol

NH3(l) → NH3(g)

3.2.3 Carbamate Condenser

Carbamate condenser is fed with overhead gaseous mixture from the top of the

stripper, In this unit the gaseous mixture is condensed and absorbed by the carbamate solution

coming from the medium pressure recovery stage. Heat liberated in the high pressure carbamate

condenser is used to generate low pressure steam. The gas and liquid from the carbamate

condensers are recycled to the reactor by gravity flow.


NH3(g) → NH3(l)

3.2.4 Scrubber

In the scrubber Ammonia and Carbon Dioxide coming from the reactor are absorbed

to ammonia and ammonium carbamate solution which is going to Carbamate Condenser.

3.2.5 Medium Pressure Decomposer

The urea solution from the stripper, with a typical NH3 content of 15 wt%, is purified

further in the medium pressure decomposer operating at 17.5 bars. No external heat supply.


NH3(l) → NH3(g)

3.2.6 Low Pressure Decomposer

After the medium pressure decomposer, further purification of urea solution occurs inside

the low pressure decomposer which is operating at 2.5 bar. External heat supply is available. all

ammonia and ammonium carbamate are removed by the Low Pressure Decomposer.


NH3(l) → NH3(g)

3.2.7 Medium Pressure Absorber

In medium pressure absorber ammonia and carbon dioxide separated from the urea

solution in medium pressure decomposer are recovered. Condensation heat in the medium

pressure absorber is transferred directly to the aqueous urea solution feed in the final

concentration section.




3.2.8 Low Pressure Absorber

In low pressure absorber ammonia and carbon dioxide separated from the urea

solution in low pressure decomposer are recovered. Heat release from that reaction is used to

produce steam at 2 bar. This steam is used for evaporation process of lower and upper separator.


3.2.9 Flash Separator

This unit is operated at 1.0 bar and 110 °C. Here by reducing the pressure, let water

to evaporate and concentrate the urea solution.

H2O(l) → H2O(g)

3.2.10 Lower Separator

This is a calendria type evaporator. This is operated at 0.55 bar vacuum pressure and

at 110 °C Here the purified urea solution is further concentrated and required heat is taken from

2 bar pressure steam produced in low pressure absorber.

3.2.11 Upper Separator

This is evaporative type separator. This is operated at 0.55 bar vacuum pressure and

at 112 °C Urea solution coming from the lower separator is further concentrated. Output from

that unit has 99.2% pure urea. After that urea solution is sent to granulation section.



3.2.12 Granulation Plant

The Urea Granulation process consists of following three

sections.

• granulation section

• recycle and product cooling section

• dust removal and recovery section

Aqueous urea solution from urea plant is fed to

the granulator to enlarge recycle particles in the granulator.

In the granulator, the granules are dried and cooled

simultaneously. The granulator is operated at 110-115oC

and at slightly negative pressure. Enlarged urea particles

are cooled to about 90ºC in the after-cooler inside the

granulator to be transported to the recycle section.

The discharged granules are separated into three sizes, product, small and large size by

the screen. Product size granules are further cooled below 60ºC in the product cooler to be sent

to the urea storage or bagging facility. Large size granules are crushed by the crusher. The rushed

particles and smaller size particles from the screen are recycled to the granulator as seed.Urea

dust contained in the exhaust air from the granulator and the product cooler is scrubbed in the

dust scrubber by contacting counter currently with aqueous urea solution. The urea dust content

in the exit air of the bag filter is 30 mg/m3 or less. Urea recovered in the bag filter, approximately

2.5-3.5 % of production rate, is recycled to the urea granulator.

Figure 3.4 Granulation plant

Figure 3.5 Spout-Fluid Bed Granulator



3.3 Typical product quality

Total Nitrogen 46.3wt%

Biuret 0.7wt%

Moisture 0.25wt%

Formaldehyde 0.45wt%

Size (2-4mm) 95wt%

Hardness 3.5kg at 3mm

Various sizes of granules

Figure 3.7 Various sizes of granules

Figure 3.6 Power Consumption of Spout-Fluid Bed Granulation

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CHAPTER 4

SITE SELECTION



4.0 Site Selection & Plant Layout

4.1 Site Selection

Site selection is the making the ultimate choice of site where business or

manufacturing plant is going to be established. It is an important task to be done in a business

case. By selecting the suitable site for the manufacturing plant it would be able to reduce the

transportation cost of raw materials and energy, make easy access to infrastructure facilities,

availability of labour force and many other benefits.

Selection should be done by considering cost and benefits of available alternative

sites. It is a strategic decision to be made, where improper decision may cause considerable loss.

So it may requied to select ideal or optimum location for the business.

Following Facts should be concern regarding site selection

Availability of raw material

Infrastructure facilities

Legal obligations enforced by relevant authority or the government

Environment and climate conditions

Labour force availability

Social considerations

Waste management

4.1.1 Availability of raw materials

Main raw materials for urea manufacturing are ammonia and carbon dioxide.

Currently ammonia plant is not there in Sri Lanka. Ammonia has to be imported from abroad.

Considering the carbon dioxide, it is emitted by number of industries as a waste from which it

has to be derived and purify. Otherwise any alternative option such as importing should be

concerned. In case of ammonia it is cost effective to locate the site near a harbor or sea where it

is directly taken in to the storage tanks. The previous urea plant was there in Sapugaskanda along

with ammonia plant and petroleum refinery. It is not viable to consider that site since ammonia

plant is not there and considering transportation cost. Considering available sites in costal areas

in Sri Lanka we select two sites Hambantota and Trincomalee for assessment. Hambantota has

many advantages regarding a large chemical plat like urea.

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Hambanthota is developing area under “Mahinda Chinthana” concept. Many

developing projects are underway. An international sea port is going to be established in

hambantota which can handle large ships which are unable to access in the Colombo port. Also

infrastructure facilities will be developed along with these projects. Vast amount of land is

available for low cost in order to establish the plant closed to Hambantota port. Even if there are

no enough qualified employees in Hambantota area, due to rapid development along with good

infrastructure facilities it would be easy to attract employees from outside areas. Government

welcomes projects related to hambantota area and many benefits can be gain such as reduction in

tax, grace periods for loans etc. The government is planning to establish a petroleum refinery in

Hambanthota. In Trincomalee much of above mentioned benefits are there, but considering the

establishment of petroleum refinery and massive port compared to Trincomalee, Hambantota

becomes the more suitable option.

It is not economical to import ammonia and carbon dioxide from abroad because of

high transportation cost and additional amount of money have to be spend on buying those

materials. Those raw materials can be produced at low cost in Sri Lanka. So it is better to have

an ammonia plant. Under the government‟s plan to establish a petroleum refinery in

Hambanthota, hydrogen can be gained as a byproduct from petroleum refinery and it can be use

as a raw material for ammonia production. So it would be better to have ammonia plant in future

to aid urea production.

4.1.2 Infrastructure facilities

Hambanthota is a one of main cities in southern part of Sri Lanka which is situated

237 km away from Colombo. Since it is a coastal area we have to consider climate as well as

infrastructure facilities such as water, electricity and roads. Direct Infrastructure facilities for

urea plant such as transportation, electricity, telecommunication and indirect infrastructures for

the employees such as education, health, food, accommodations etc. are being recently

developed in Hambantota. On the other hand in Hambanthota there is scarcity of sufficient water

reservoirs for the various purpose of the urea plant due to dry zone. But we can fulfill some

amount of our water requirement like cooling water using sea water and other requirements using

water distribution project which is being develop along with other development projects.

Highways are being constructed connecting hambantota port and other developing sites such as

air port. So Transportation of other required materials would be more convenient. Other private

and public sector facilities including telecommunication, government authorities will also be

developed.



4.1.3 Legal obligations enforced by relevant authority or the government

Yala Sanctuary Park is situated in Hambanthota area. So government obligation may

arise for such a urea manufacturing plant construction. Some families may have to resettle to

clear the construction area of urea manufacturing plant. Legal obligations may arise from people.

Compensation and resettlement should be done in order to avoid such difficulties. Since

chemicals are used in the manufacturing it would be necessary to comply with government

regulations regarding handling and storing of such chemicals. Emissions from the urea plant

should be under permissible conditions. Since site is in costal area air emissions may not have

much impact. Sound regulations may not have to be considered extensively since area is remote.

Tax and other financial considerations may vary with related to selected site.

4.1.4 Environment and Climate Conditions

Hambantota is located in semi-arid zone in Sri Lanka. Climate is much dryer, but in

the coastal side it is much humid so it can lead to corrosion in metallic component in the plant.

Law rain fall is an advantage for urea production. Because of coastal wind emissions from the

plant may dilute easily and air emission problems may not arise. Only difficulty is the lack of

water resources. Sea water should be utilized in order to fulfill water requirement for some

extent. But water is needed to be transported from available area nearby. Accommodation for

labours and other staff should be constructed considering dry weather.

4.1.5 Labour Force availability

Many people in rural areas like Hambantota are not permanently employed. People

from villages may move in to cities nearby or even to Colombo to find employment. So

establishing a plant in such area will produce around 1200 direct jobs and many other indirect

job opportunities. It will solve unemployment problem to considerable extent. So labour

availability is not an issue, but difficulties may arise in finding qualified people.

4.1.6 Social considerations

Obstacles may arise from residential people and from environmentalists. Peoples will

resist construction work and may take legal actions. Proper mechanism to resettle residential

people who may lose their homes should be established collaboration with government.

Environmental concerns should be considered including air emissions, waste disposal, sound

levels and necessary steps should be take to control or maintain under permissible levels. Also

site should cause minimum environment damage during construction and operation.



4.1.7 Waste Management

Waste management restrictions are being enforced by the regulations. Plant site

should accommodate disposal of waste in to the sea or to the land. Chemical wastes are there

from the plants which are considered hazardous. Selected site should have facilities for both

waste processing and for storage until waste is properly disposed. Social considerations are

important in waste management. Locating plant in a remote location is an advantage.

4.2 Plant Layout

The efficiency of production depends on how well the various machines; production

facilities and employee‟s amenities are located in a plant. Only the properly laid out plant can

ensure the smooth and rapid movement of material, from the raw material stage to the end

product stage.

Plant layout refers to the arrangement of physical facilities such as machinery,

equipment, storages, departments etc. with in the factory building in such a manner so as to have

quickest flow of material at the lowest cost and with the least cost in processing the product from

the raw material to the finished product.

4.2.1 Importance

Plant layout is an important decision as it represents long-term commitment. An ideal

plant layout should provide the optimum relationship among output, floor area and

manufacturing process. It facilitates the production process, minimizes material handling, time

and cost, and allows flexibility of operations, easy production flow, makes economic use of the

building, promotes effective utilization of manpower, and provides for employee‟s convenience,

safety, comfort at work, maximum exposure to natural light and ventilation. It is also important

because it affects the flow of material and processes, labour efficiency, supervision and control,

use of space and expansion possibilities etc.

An efficient plant layout is one that can be instrumental in achieving the Following objectives:

a) Proper and efficient utilization of available floor space

b) To ensure that work proceeds from one point to another point without any delay

c) Provide enough production capacity.

d) Reduce material handling costs

e) Reduce hazards to personnel

f) Utilize labour efficiently



g) Increase employee morale

h) Reduce accidents

i) Provide for volume and product flexibility

j) Provide ease of supervision and control

k) Provide for employee safety and health

l) Allow ease of maintenance

m) Allow high machine or equipment utilization

n) Improve productivity

4.3 Environmental Impact Assessment

An Environment Impact Assessment is an assessment of the possible positive impact

or negative impact which the project may have on the natural environment. The purpose of the

assessment is to ensure that decision makers consider environmental impacts used to decide

whether to proceed with the project. The International Association for Impact Assessment

(IAIA) defines an environmental impact assessment as "the process of identifying, predicting,

evaluating and mitigating the biophysical, social, and other relevant effects of development

proposals prior to major decisions being taken and commitments made.

4.3.1 Objectives of EIA Assessment

To ensure that proponents take primary responsibility for protection of the environment

influenced by their proposals

To ensure that best practicable measures are taken to minimize adverse impacts on the

environment, and that proposals meet relevant environmental objectives and standards to

protect the environment, and implement the principles of sustainability

To provide opportunities for local community and public participation, as appropriate,

during the assessment of proposals

To encourage proponents to implement continuous improvement in environmental

performance and the application of best practice environmental management in

implementing their proposal

To ensure that independent, reliable advice is provided to the Government before

decisions are made

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4.3.2 Impact of the Urea Plant on the environment

In the early part of previous decade ammonia consumption per ton of final product of 575

kg or even higher used to be acceptable. This figure implies however a loss of some 8 kg per

tonne of final product produced (Table 1), which for a 2000 mtd plant would result in a loss of

16 mtpd ammonia either in the form of urea or straight ammonia.

Presently ammonia consumptions of some 567 kg per tonne are released in the large single

stream plants. Since this figure is very close to the theoretical consumption figure, the conclusion

is that losses in steady operation are approaching the zero targets.

Ammonia releases from urea plants

Early nineteen eighties

Presently

8 kg NH3/mt final product

0.7 kg NH3/mt final product

Not only ammonia, carbon dioxide and urea releases from process plants have a

negative influence on the environment but also the unnecessary use of energy is negative from an

environmental point of view and from the economic point of view as well.

Following table shows the present typical energy consumption for urea production

Typical consumption figures for a granulation plant

Steam (22 bar, 330oC)

Steam (4 bar saturated) (production)

Electricity (including granulation section)

Cooling water (including granulation section)

805 kg/mt urea

-415 kg/mt urea

50 kWh/mt urea

58 mt/mt urea

Emissions from Urea manufacturing process are listed below.

Substance

Emission Media

To

Atmosphere To Water Via Solid Waste

Ammonia

Formaldehyde

Methanol

Total Nitrogen

Particulate Matter (PM10)

Volatile Organic

Compounds(VOCs)

Table 4.3 Emissions from Urea manufacturing process

Table 4.2 Typical consumption figures for a granulation plant

Table 4.1 Ammonia releases from urea plants

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4.3.3 Emissions to Air

Air emissions may be categorised as either fugitive or point source emissions.

Fugitive Emissions

These are emissions that are not released through a vent or stack. Examples of fugitive

emissions include dust from stockpiles, volatilization of vapour from vats, open vessels, or

spills and materials handling. Emissions emanating from ridgeline roof-vents, louvres, and

open doors of a building as well as equipment leaks, and leaks from valves and flanges are

also examples of fugitive emissions.

Point Source Emissions

These emissions are exhausted into a vent or stack and emitted through a single point source

into the atmosphere. Above table highlights common air emissions from urea manufacturing

processes.

4.3.4 Emissions to Water

Emissions of substances to water can be categorised as discharges to:

Surface waters (eg. lakes, rivers, dams, and estuaries);

Coastal or marine waters

Storm water

Because of the significant environmental hazards posed by emitting toxic substances

to water, most facilities emitting above listed substances to waterways are required by the

relevant environment authority to closely monitor and measure these emissions. The existing

sampling data can be used to calculate annual emissions. If no wastewater monitoring data

exists, emissions to process water can be calculated based on a mass balance or using emission

factors.

4.3.5 Emissions to Land

Emissions of substances to land on-site include solid wastes, slurries, and sediments.

Emissions arising from spills, leaks, and storage and distribution of materials containing listed

substances may also occur to land. These emission sources can be broadly categorised as:

surface impoundments of liquids and slurries; and

unintentional leaks and spills.

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In general, there are four types of emission estimation techniques (EETs) that may be used to

estimate emissions from the facility. The four types are:

Sampling or direct measurement;

Mass balance;

Fuel analysis or other engineering calculations; and

Emission factors

4.3.6 Elimination Methods

Presently plants are equipped with the following features to keep the effluent and emission at

extremely low levels:

N/C ratio meter

Waste water treatment section

Absorbers

Special operational facilities

N/C ratio meter in the Synthesis section

Instead of using a gaschromatograph or a mass spectrometer in the gas phase of the

synthesis section, Nitrogen/Carbon (N/C) ratio meters are installed in the liquid phase (reactor

liquid outlet) of the urea synthesis section

The principle of this N/C meter is based on the linear relationship between liquid

density and the N/C ratio. The density is measured continuously with a solartron meter, being an

instrument in which vibrations are measured in an extremely accurate way whereby the

vibrations are a measure of the density of the reactor liquid.

This N/C ratio meter allows the process at all times to be operated at the optimum ratio to

achieve highest reactor efficiency combined with higher energy efficiency. Special procedures

are used to eliminate emissions during start-up.

Urea plant waste water treatment section

The process water in urea plants contains ammonia, carbon dioxide and urea. The

concentrations of these components vary within a range depending on the operating conditions,

On average, the concentrations in the process water are about 6 wt.% ammonia, 4 wt.% carbon

dioxide and 1 wt.% urea.

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Sources of the ammonia and urea are

Condensate from the evaporators.

Off-gases from the recirculation section, which are absorbed in the process water.

Off-gases from the synthesis section, which are absorbed in the process water.

Flush and purge water for pumps.

Liquid drains.

The purpose of the process water treatment is to remove ammonia, carbon dioxide

and urea from the process condensate. For every tonne of urea produced, approximately 0.3

tonnes of water are formed. This water is usually discharged from the urea concentration and

evaporation section of the plant. Removal of ammonia and urea from wastewaters can be a

problem as it is difficult to remove one in the presence of the other. One method used to

overcome this problem is the hydrolysis of urea to ammonium carbamate, which is decomposed

to ammonia and carbon dioxide. These gases can then be stripped from the wastewaters. Urea

plants are in operation that produces wastewaters with ammonia and urea levels below 1ppm.

This water can then be used for a variety of purposes depending on the required quality such as

cooling water or Boiling Feed Water make-up. The recovered ammonia and carbon dioxide are

returned to the process to be subsequently converted into urea.

Absorbers

Absorbers are used in urea plant to eliminate emissions to the atmosphere, can be classified as

follows:

(1) The vent from the synthesis section of the plant

The purge from the urea synthesis section contains inerts, ammonia and carbon

dioxide. To avoid ammonia emissions from this purge a low pressure absorber is installed in

purge stream. First the ammonia is washed out with a large flow of low concentrated and cooled

process water and secondly the remaining ammonia is absorbed in cooled condensate or clean

waste water.

(2) The vent from the low pressure section of the plant

The ammonia and carbon dioxide present in the off gases of the recirculation section,

the Process Water Treatment System and the evaporation section are washed out in an

atmospheric absorber where large amounts of cooled low concentrated process water are used to

absorb all the ammonia present in said off gases.



Special start-up, shut-down and draining facilities

Because of the present low releases during steady state operation in urea

manufacturing the consideration regarding environmental issues has changed towards further

reducing of effluents and emissions from non-continuous sources during non-steady state

conditions such as start-up and shut-down situations. A change in the start-up procedure of the

urea synthesis section has reduced the impact on the environment considerably.

Presently the ability to measure the feed flows (NH3

and CO2) very accurate in

combination with the ability to measure the N/C ratio have enabled us to feed the synthesis

section from the very beginning of the start-up with the correct NH3/CO

2 ratio, thus eliminating

the need, during the initial stage of start-up, to vent excess CO2

accompanied by some NH3

into

the atmosphere.

Special shut-down and draining facilities assure that non converted NH3

and CO2

are

recovered by the process after a shut-down. To achieve this facility to feed clean water to dilute

the carbamate formed from non converted NH3

and CO2

from the synthesis section has been

introduced.

The dilution should be to the extent that no ammonia will escape from the liquid

under atmospheric pressure. The water is in principle introduced in the low pressure carbamate

condenser and subsequently cooled to increase absorption capacity, and drained in the ammonia

water tank. After restart of the plant the NH3

and CO2

in this tank are recovered via the waste

water treatment section. The clean water used for the dilution may be an amount of clean waste

water stored for such purpose. In case sufficient condensate is available in the complex no such

additional storage of clean waste water is required and condensate may be used as well.

4.4 Safety Of the Urea Plant

It is must to consider occupational safety and health when designing a manufacturing

plant. Safety is the major factor in any industrial process to safeguard employees, environment,

surrounding living peoples etc. Also there are legal obligations which are imposed by

government for chemical processing factories to operate and maintain.

When considering the safety, it is mainly due to the risk of urea which is the main

product of plant and ammonia; one of the main raw materials for production and risk caused by

other intermediate product.



4.4.1 Safety factors relevant to urea

Stability and Reactivity

Produce biuret when expose to heat

Urea has high solubility. So it should store under dry conditions.

It has high stability and low reactivity with normal conditions

Flammability

Urea is non-flammable material

Flash point: Not applicable

Flammability limits: Not applicable

Auto-ignition temperature: Not applicable

The substance decomposes on heating above melting point, producing toxic gases,

and reacts violently with strong oxidants, nitrites, inorganic chlorides, chlorites and perchlorates,

causing fire and explosion hazard

Hazard identification

Classified as hazardous chemical according to criteria in the HS (Minimum Degrees of Hazard)

Regulations 2001

Route of entry and health hazards

Harmful if swallowed. - It may cause irritation

Harmful if inhaled.

Causes serious eye irritation.

Harmful to terrestrial vertebrates.

Inhalation: Slight irritant. Elevated exposure may result in mucous membrane irritation (nose &

throat). may cause nausea, vomiting, diarrhea and GI irritation.

Skin: Irritant. Prolonged contact may result in irritation, itching and possible skin rash.

Eyes: Irritant. May cause lachrymation, irritation, pain & redness

Ingestion: Has diuretic effect. Ingestion of large quantities may lead to nausea and vomiting.

No adverse health effects expected under normal conditions. Urea can be irritating to

skin and eyes.Too high concentrations in the blood can cause damage to organs of the body. Low

concentrations of urea such as in urine are not dangerous. It has been found that urea can cause



algal blooms to produce toxins, and urea in runoff from fertilizers may play a role in the increase

of toxic blooms.

First aid (Emergency procedure)

In the event of an emergency, remove the victim from further exposure, send for medical

assistance, and initiate the following emergency procedures:

Skin

Wash exposed area with soap and water. If irritation persists, get medical attention as

soon as possible.

Eyes

Wash eyes with plenty of water for at least 15 minutes, lifting lids occasionally. Seek

Medical Aid.

Inhalation

Remove to fresh air. If not breathing, give artificial respiration. If breathing is difficult,

give oxygen

Ingestion

If swallowed, induce vomiting immediately after giving two glasses of water. Never give

anything by mouth to an unconscious person.

Fire Extinguisher

Any means suitable for extinguishing surrounding fire. Fire extinguisher should available in any

risky places in the plant.

Extinguishing media: CO2, foam, dry powder, water

Handling & Storage

Precautionary Statements

Keep out of reach of children.

Avoid breathing vapors, or dusts.

Wash hands thoroughly after handling.

Do not eat drink or smoke when using this product.

Avoid unintended release to the environment.

Use with adequate ventilation.

Avoid contact with eyes, skin, and clothes.



Safe Handling

Avoid generating dusts. Use only outdoors or in a well-ventilated area.

Storage

Store in sealed containers in cool, dry, well ventilated place away from incompatible

materials. Wash thoroughly after handling.

Keep container closed.

Transportation

No special transport requirements necessary

Environmental Exposure Limit (EEL): Not assigned

Avoid washing excessive amounts into streams and waterways.

Exposure Controls & Personal Protection

Exposure Standards

Workplace Exposure Standards (WES): Particulates not otherwise classified

Inspirable dust 10mg/m3

Respirable dust 3mg/m3

Personal Protective Equipment

Respiratory: If dusts particles are present wear suitable dust mask.

Eyes/Face: Safety glasses. If dusts present wear goggles.

Skin: use Overalls and gloves.

Eye wash facilities should be available.

Wash hands after working with substance.

Collect and place in clean sealable containers.

Avoid generating dusts.

Engineering Controls

Ventilation: Use in well ventilated area. If dusts are generated use local extraction to control

Disposal Considerations

Observe local authority restrictions that may apply. Collection into sealable

containers and dispose of in an approved land fill. If practicable apply excess fertilizer at

recommended rates to appropriate land. Rinse containers thoroughly prior to re-use. Otherwise

render unusable, and dispose of as waste.



4.4.2 Safety Factors Relevant to Ammonia

Stability and reactivity

Ammonia has very low stability because it converts to ammonium hydroxide or other

ammonium salt by combining with water or other salts. But it has no reactivity under normal

conditions.

Incompatible materials

Ammonia reacts vigorously with fluorine, chlorine, HCl, HBr, nitrosyl chloride,

chlorine monoxide, aldehydes, boron, boron halides, calcium, amides, chromyl chloride, nitrogen

dioxide, trioxygen difluoride, and nitrogen trichloride , halogens, heavy metals and many other

materials.

Hazardous decomposition products form with hydrogen at very high temperature.

Hazardous polymerization will not occur.

Flammability

Ammonia is slightly flammable material.



Auto-ignition temperature: 1274oF


Irritating or corrosive to exposed tissues. Inhalation of vapors may result in pulmonary edema

and chemical pneumonitis

Route of entry and health hazards

Harmful if contact with eye

Harmful if inhaled.

Irritant if contact with skin and eye

Eye effects

Mild concentrations of product will cause conjunctivitis. Contact with higher

concentrations of product will cause swelling of the eyes and lesions with a possible

loss of vision.



Exposure to 50 ppm or less for 5 minutes was not considered irritating by volunteers,

while exposure to 72 ppm was irritating to a few individuals and 134 ppm was irritating and

caused tearing. At 700 ppm, the gas is immediately and severely irritating.

Direct contact with the liquefied gas can cause frostbite and corrosive injury to eye.

Permanent eye damage or blindness could result. Severe, permanent eye injury, including an

almost complete loss of vision, has been reported following direct contact with liquefied

ammonia gas.

Skin effects

Mild concentrations of product will cause dermatitis or conjunctivitis. Contact with

higher concentrations of product will cause caustic-like dermal burns and

inflammation. Toxic level exposure may cause skin lesions resulting in early necrosis

and scarring.

High levels of airborne ammonia gas dissolve in moisture on the skin, forming corrosive

ammonium hydroxide. At 10000 ppm, ammonia is mildly irritating to moist skin. At 20000 ppm,

the effects are more pronounced and 30000 ppm may produce chemical burns with blistering.

These same exposure levels would be almost certainly fatal due to inhalation health effects.

Direct contact with liquefied gas can cause frostbite and corrosive burns. Symptoms

of mild frostbite include numbness, prickling and itching in the affected area. Symptoms of more

severe frostbite include a burning sensation and stiffness of the affected area. The skin may

become waxy white or yellow. Blistering, tissue death and gangrene may also develop in severe

cases. Corrosive burns of the skin have resulted from direct contact with a jet of liquefied

ammonia. Permanent scarring of the skin may result.

Ingestion effects

Since product is a gas at room temperature, ingestion is unlikely.

Inhalation effects

Corrosive and irritating to the upper respiratory system and all mucous type tissue.

Depending on the concentration inhaled, it may cause burning sensations, coughing,

wheezing, shortness of breath, headache, nausea, with eventual collapse.

Toxic effects to the respiratory system, senses, liver, kidneys and bladder observed in

mammalian species from prolonged inhalation exposures at above 100 ppm Inhalation of

excessive amounts affects the upper airway (larynx and bronchi) by causing caustic-like burning



resulting in edema and chemical pneumonitis. If it enters the deep lung, pulmonary edema will

result. Pulmonary edema and chemical pneumonitis are potentially fatal conditions.

Long term health effects of exposure to Ammonia gas

No significant differences in lung function were observed in workers exposed to 9.2

ppm ammonia for an average of 12.2 years compared to controls with very low exposure (less

than 1 ppm). No conclusions can be drawn from one case report which described lung injury

following long-term exposure to ammonia because the person was a long-term smoker. People

with repeated exposure to ammonia may develop a tolerance (or acclimatization) to the irritating

effects after a few weeks.


Eyes

Flush contaminated eye(s) with copious quantities of water. Part eyelids to assure

complete flushing. Continue for a minimum of 15 minutes. Persons with potential

exposure to ammonia should not wear contact lenses.

Skin

Remove contaminated clothing as rapidly as possible. Flush affected area with

copious quantities of water. In cases of frostbite or cryogenic "burns" flush area with

lukewarm water. Do not use hot water. A physician should see the patient promptly if

the cryogenic "burn" has resulted in blistering of the dermal surface or deep tissue

freezing.

Ingestion

Not specified. Seek immediate medical attention.

Inhalation

Prompt medical attention is mandatory in all cases of overexposure. Rescue personnel

should be equipped with self-contained breating apparatus. Conscious persons should

be assisted to an uncontaminated area and inhale fresh air. Quick removal from the

contaminated area is most important. Unconscious persons should be moved to an

uncontaminated area, given mouth-to-mouth resuscitation and supplemental oxygen.

Keep victim warm and quiet. Assure that mucus or vomited material does not

obstruct the airway by positional drainage.



Fire Extinguisher

Extinguisher media

Water fog, foam. Use media suitable for surrounding fire.

Fire extinguished instruction

If possible, stop the flow of gas. Since ammonia is soluble in water, it is the best

extinguishing media not only in extinguishing the fire, but also absorbing the escaped

ammonia gas. Use water spray to cool surrounding containers.

Handling & Storage

Earth-ground and bond all lines and equipment associated with the ammonia system.

Electrical equipment should be non-sparking or explosion proof.

Gaseous or liquid anhydrous ammonia corrodes certain metals at ambient

temperatures. The presence of oxygen enhances the corrosion of ordinary or semi-

alloy steels. The addition of water inhibits this enhancement. Keep anhydrous

ammonia systems scrupulously dry.

Use only in well-ventilated areas. Valve protection caps must remain in place unless

container is secured with valve outlet piped to use point. Do not drag, slide or roll

cylinders. Use a suitable hand truck for cylinder movement. Use a pressure regulator

when connecting cylinder to lower pressure (<500 psig) piping or systems. Do not

heat cylinder by any means to increase the discharge rate of product from the

cylinder. Use a check valve to trap in the discharge line to prevent hazardous back

flow into the cylinder.

Protect cylinders from physical damage. Store in cool, dry, well-ventilated area away

from heavily trafficked areas and emergency exits. Do not allow the temperature

where cylinders are stored to exceed 125oF (52oC). Cylinders should be stored

upright and firmly secured to prevent falling or being knocked over. Full and empty

cylinders should be segregated. Use a "first in-first out" inventory system to prevent

full cylinders from being stored for excessive periods of time.

Never carry a compressed gas cylinder or a container of a gas in cryogenic liquid

form in an enclosed space such as a car trunk, van or station wagon. A leak can result

in a fire, explosion, asphyxiation or a toxic exposure.



Engineering controls

Use local exhaust ventilation to reduce concentrations to within current exposure limits.

A laboratory type hood is suitable for handling small or limited quantities.

Personal protection

Eye/face protection

Gas tight chemical goggles or full-face piece respirator.

Skin protection

Protective gloves made of any suitable material.

Respiration protection

Respiratory protection with full face piece or self-contained breathing apparatus

should be available for emergency use. Air purifying respirators must be equipped

with suitable cartridges. Do not exceed maximum use concentrations. Do not use air

purifying respirators in oxygen deficient/immediately dangerous to life and health

(IDLH) atmosphere. Consult manufacturer‟s instructions before use.

Other general protections

Safety shoes, safety shower, eyewash "fountain".


Do not attempt to dispose of residual waste or unused quantities. Return in the

shipping container properly labeled, with any valve outlet plugs or caps secured and valve

protection cap in place to BOC Gases or authorized distributor for proper disposal.

4.4.3 Safety Factors Relevant to Ammonium Carbamate


Ammonium carbamate is stable compound, but may be moisture sensitive.

Incompatible with strong oxidizing agents, strong acids, strong bases

Hazardous polymerization will not occur

Decompose to ammonia and carbon dioxide when heated up to 140oF

Incompatible materials

Strong acids. Ammonium carbamate reacts with chlorine, bromine, mercury, silver

and hypochlorite to form explosive compounds.



Flammability

Ammonium carbamate is not a flammable material

Ammonia vapors in the range of 16% to 25% by volume in air can explode on

contact with an ignition source. The use of welding or flame cutting equipment on process lines

is not recommended unless all ammonium carbamate has been removed. Avoid welding in

confined space.



Auto-ignition temperature: not applicable


Ammonium carbamate has a potential for acute health effects

Eyes and Skins

Eyes: Noticeable irritation to the eyes will occur at ammonia concentrations of 100

PPM. Severe irritation to the eyes will occur at concentrations of 400 PPM.

Skin: Contact with ammonium carbamate can result in first, second and third degree

burns.

Inhalation

Severe irritation of nose and throat occurs at ammonia concentrations of 400 PPM.

Serious coughing and bronchial spasms occur at ammonia concentrations of 1,700

PPM. Less than a thirty minute exposure to ammonia concentrations of 1,700 PPM

may be fatal. IDLH at 300 PPM.

Ingestion

Ingestion may be fatal. May result in first, second or third degree burns.


Eyes

Immediately flood with large amounts of water for at least 15 minutes. Seek medical

attention.

Skin

Remove contaminated clothing immediately. Flush the skin with large amounts of

water until all material is removed (at least 15 minutes). Wash all contaminated

clothing before re-use.



Ingestion

Do not induce vomiting. Encourage the victim to drink large amounts of water,

substituting as available, diluted vinegar, lemon juice or orange juice.

Inhalation

Use respiratory protection as necessary and remove to fresh air at once. If breathing

stops, administer artificial respiration

Fire Extinguisher

Extinguisher media: Water

Avoid direct streams of water application which may result in chemical exposure due

to splashing Fire extinguishing agents to avoid CO2 may react violently.

Use water spray to control ammonia vapors. Adding water to ammonium carbamate

will generate heat and increase the ammonia vapors generated. Wear full protective

clothing with an approved self contained breathing apparatus.

Storage and Handling

Provide ventilation sufficient to maintain exposure to ammonia vapors below the

permissible exposure limit.

Avoid all contact with the body. Minimize gas contact. Employ good maintenance

practices to prevent leaks. Keep away from heat and open flames. Use good process

control measures to prevent releases.

Preferably stored outside. Otherwise in cool, dry well-ventilated non-combustible

location away from all ignition sources and oxidizers.

Exposure Controls/Personal Protection


Vessel and drum labels are required on all containers. Personnel training should include

adequate inspection techniques on equipment such as pumps, hoses, and valves.

Eye Protection

Face shield and tight fitting gas tight splash goggles

Protective Clothing

Chemical resistant suit with rubber or vinyl gloves and rubber boots



Respiratory Protection

Use a NIOSH/MSHA approved full-face negative pressure respirator fitted with

ammonia cartridges for exposures at or below 300 PPM. For concentrations above 300

PPM, use a full-face positive pressure self-contained breathing apparatus

Other Protective Clothing or Equipment

Provide an eyewash station and safety shower at sites handling or storing Ammonium

Carbamate.


Product Disposal

Disposal of ammonium carbamate may be subject to federal, state and local regulations.

General Comments

Handlers of this product should review their operations in terms of applicable laws and

regulations, and then consult with appropriate regulatory agencies before discharging or

disposing of any waste material.

4.4.4 Safety Factors Relevant to Biurete (byproduct)


Product is very stable under normal conditions

Stability is not change with temperature

Stability is not change with varies conditions

Not available incompatibility substances

Non-corrosive in presence of glass.

Polymerization will not occur.

Flammability

Not flammable under normal conditions and may be combustible at high temperature.

Auto-Ignition Temperature: Not available.

Flash Points: Not available.

Flammable Limits: Not available

After the combustion products are carbon oxides (CO, CO2), nitrogen oxides (NO, NO2...).




Potential Acute Health Effects:

Hazardous in case of skin contact (irritant), of ingestion, of inhalation. Slightly

hazardous in case of skin contact (permeator), of eye contact (irritant).

Potential Chronic Health Effects:

Hazardous in case of skin contact (irritant), of ingestion, of inhalation.

Slightly hazardous in case of skin contact ( permeator ), of eye contact (irritant).

No carcinogenic effects

No mutagenic effects

No teratogenic effects


Eye

Check for and remove any contact lenses. In case of contact, immediately flush eyes

with plenty of water for at least 15 minutes. Cold water may be used. Get medical

attention if irritation occurs.

Skin

In case of contact, immediately flush skin with plenty of water. Cover the irritated

skin with an emollient. Remove contaminated clothing and shoes. Cold water may be

used. Wash clothing before reuse. Thoroughly clean shoes before reuse. Get medical

attention.

Serious Skin Contact

Wash with a disinfectant soap and cover the contaminated skin with an anti-bacterial

cream. Seek medical attention.

Inhalation

If inhaled, remove to fresh air. If not breathing, give artificial respiration. If breathing

is difficult, give oxygen. Get medical attention.

Ingestion

Do not induce vomiting unless directed to do so by medical personnel. Never give

anything by mouth to an unconscious person. If large quantities of this material are

swallowed, call a physician immediately. Loosen tight clothing such as a collar, tie,

belt or waistband.

If the contamination is series it should call a doctor immediately



Fire Extinguisher

Small fire: Use dry chemical powder.

Large fire: Use water spray, fog or foam. Do not use water jet.

Handling and storage

Keep away from heat. Keep away from sources of ignition. Empty containers pose a fire

risk; evaporate the residue under a fume hood. Ground all equipment containing material. Do not

breathe dust. Avoid contact with skin. Wear suitable protective clothing. In case of insufficient

ventilation, wear suitable respiratory equipment. If you feel unwell, seek medical attention and

show the label when possible. Keep container tightly closed. Keep container in a cool, well-

ventilated area.

Exposure Controls & Personal Protection


Use process enclosures, local exhaust ventilation, or other engineering controls to keep

airborne levels below recommended exposure limits. If user operations generate dust, fume or

mist, use ventilation to keep exposure to airborne contaminants below the exposure limit.

Personal Protection

Ware safety glasses, Lab coat, Dust respirator. Be sure to use an approved/certified

respirator or equivalent, Gloves.

In large Spill use Splash goggles, Full suit, Dust respirator, Boots, Gloves. A self

contained breathing apparatus should be used to avoid inhalation of the product. Suggested

protective clothing might not be sufficient; consult a specialist before handling this product.



CHAPTER 5

MASS BALANCE CALCULATION



5.0 Mass Balance Calculation

5.1 Material Balance

Urea production per day = 1060.0 MT

CO2 conversion = 68.00%

CO2 requirement per day = 777.3 MT

NH3 requirement per day = 600.7 MT

Compound Chemical Formula Molecular Weight (kg/kmol)

Ammonia NH3 17

Carbon dioxide CO2 44

Ammonium Carbamate NH2COONH4 78

Water H2O 18

Urea NH2CONH2 60

Input ratio to reactor NH3 : CO2

Molar ratio 4 : 1

Weight ratio 68 : 44

Reactions involved in the process

2NH3 + CO2 ↔ NH2COONH4 + heat

Sch 2 1 1

Mass 34 44 78

Wt% 0.4359 0.5641 1.0000

NH2COONH4 + heat ↔ NH2CONH2 + H2O

Sch: 1 1 1

Mass 78 60 18

Wt% 1.0000 0.7692 0.2308

Table 5.1 Compound in urea manufacturing

tcs

Highlight

tcs

Highlight

tcs

Highlight

tcs

Highlight



2NH3 + CO2 ↔ NH2CONH2 + H2O

Sch: 2 1 1 1

Mass 34 44 60 18

Wt% 0.4359 0.5641 0.7692 0.2308

tcs

Highlight



5.1.1 Reactor

Component

Weight

MT/day Wt %

CO2 263.3 100.00%

Flow rate 263.3 MT/day

Temperature 170 °C

Pressure 175 bar

Component

Weight

MT/day Wt %

NH3 4.8 12.79%

CO2 32.4 87.21%

Flow rate 37.2 MT

Temperature 190 °C

Pressure 175 bar

Component

Weight

MT/day Wt %

NH3 486.1 23.76%

A. Carbamate 1559.7 76.24%


Temperature 170 °C

Pressure 175 bar

Component

Weight

MT/day Wt %

Urea 1060.0 36.90%

Carbamate 591.0 20.57%

NH3 903.6 31.46%

H2O 318.0 11.07%


Temperature 190 °C

Pressure 175 bar

Component

Weight

MT/day Wt %

NH3 600.7 100.00%


Temperature 170 °C

Pressure 175 bar



MP

STEAM

COND.

5.1.2 Stripper

Component

Weight

MT/day Wt %

CO2 700.0 100.00%

Flow rate 700.0 MT

Temperature 110 °C

Pressure 175 bar

Component

Weight

MT/day Wt %

Urea 1060.0 36.90%


NH3 903.6 31.46%

H2O 318.0 11.07%


Temperature 190 °C

Pressure 175 bar

Component

Weight

MT/day Wt %

NH3 612.4 44.89%

CO2 751.8 55.11%


Temperature 190 °C

Pressure 175 bar

Component

Weight

MT/day Wt %

Urea 1060.0 48.00%


NH3 331.3 15.00%

H2O 318.0 14.40%


Temperature 178 °C

Pressure 175 bar



SC

STM


Component

Weight

MT/day Wt %

NH3 612.4 44.89%

CO2 751.8 55.11%


Temperature 190 °C

Pressure 175 bar

Component

Weight

MT/day Wt %

NH3 56.4 26.89%

CO2 22.7 10.82%



Temperature 153 °C

Pressure 175 bar

Component

Weight

MT/day Wt %

NH3 212.3 28.89%



Temperature 150 °C

Pressure 175 bar

Component

Weight

MT/day Wt %

CO2 263.3 100.00%

Flow rate 263.3 MT

Temperature 170 °C

Pressure 175 bar

Component

Weight

MT/day Wt %

CO2 263.3 14.44%

Carbamate 1559.7 85.56%


Temperature 170 °C

Pressure 175 bar



5.1.4 Scrubber

Component

Weight

MT/day Wt %

NH3 1.4 12.79%

CO2 9.7 87.21%


Temperature 189 °C

Pressure 175 bar

Component

Weight

MT/day Wt %

NH3 53.1 28.89%



Temperature 150 °C

Pressure 175 bar

Component

Weight

MT/day Wt %

NH3 4.8 12.79%

CO2 32.4 87.21%

Flow rate 37.2 MT

Temperature 190 °C

Pressure 175 bar

Component

Weight

MT/day Wt %

NH3 56.4 26.89%

CO2 22.7 10.82%



Temperature 153 °C

Pressure 175 bar



5.1.5 High Pressure Decomposer

Component

Weight

MT/day Wt %

NH3 327.3 79.49%

CO2 84.5 20.51%


Temperature 157 °C

Pressure 17.5 bar

Component

Weight

MT/day Wt %

Urea 1060 59.00%


NH3 69.3 3.85%

H2O 318.0 17.70%


Temperature 157 °C

Pressure 17.5 bar

Component

Weight

MT/day Wt %

Urea 1060.0 48.00%


NH3 331.3 15.00%

H2O 318.0 14.40%


Temperature 178 °C

Pressure 175 bar



5.1.6 Low Pressure Decomposer

Component

Weight

MT/day Wt %

NH3 221.5 44.67%

CO2 274.4 55.33%


Temperature 129 °C

Pressure 2.5 bar

Component

Weight

MT/day Wt %

Urea 1060 59.00%


NH3 69.3 3.85%

H2O 318.0 17.70%


Temperature 157 °C

Pressure 17.5 bar

Component

Weight

MT/day Wt %

H2O 20 94.79%

Urea 0.6 2.84%

NH3 0.5 2.37%


Temperature 129 °C

Pressure 2.6 bar

Component

Weight

MT/day Wt %

Urea 1060.6 75.81%

H2O 338.0 24.16%

NH3 0.5 0.04%


Temperature 129 °C

Pressure 2.5 bar

Component

Weight

MT/day Wt %

CO2 77.3 100.00%

Flow rate 77.3 MT

Temperature 80 °C

Pressure 20 bar



5.1.7 Low Pressure Absorber

Component

Weight

MT/day Wt %

NH3 221.5 44.67%

CO2 274.4 55.33%


Temperature 129 °C

Pressure 2.5 bar

Component

Weight

MT/day Wt %

NH3 9.5 1.91%



Temperature 129 °C

Pressure 1.5 bar

CW



5.1.8 Medium Pressure Absorber

Component

Weight

MT/day Wt %

NH3 328.7 77.73%

CO2 94.2 22.27%


Temperature 151 °C

Pressure 17.5 bar

Component

Weight

MT/day Wt %

NH3 265.4 28.89%

CO2 0.0 0.00%



Temperature 150 °C

Pressure 12 bar

Component

Weight

MT/day Wt %

NH3 9.5 1.91%



Temperature 129 °C

Pressure 17.5 bar



5.1.9 Flash Separator

Component

Weight

MT/day Wt %

H2O 105.6 99.53%

Urea 0.3 0.28%

NH3 0.2 0.19%


Temperature 190 °C

Pressure 0.55 bar

Component

Weight

MT/day Wt %

Urea 1060.6 75.81%

H2O 338.0 24.16%

NH3 0.5 0.04%


Temperature 178 °C

Pressure 2.5 bar Component

Weight

MT/day Wt %

Urea 1060.3 82.00%

H2O 232.4 17.98%

NH3 0.3 0.02%


Temperature 110 °C

Pressure 0.7 bar



5.1.10 Lower Separator

Component

Weight

MT/day Wt %

H2O 152.8 99.74%

Urea 0.2 0.13%

NH3 0.2 0.13%


Temperature 110 °C

Pressure 0.55 bar

Component

Weight

MT/day Wt %

Urea 1060.3 82.00%

H2O 232.4 17.98%

NH3 0.3 0.02%


Temperature 110 °C

Pressure 2 bar

Component

Weight

MT/day Wt %

Urea 1060.1 93.00%

H2O 79.7 6.99%

NH3 0.1 0.01%


Temperature 110 °C

Pressure 0.7 bar



5.1.11 Upper Separator

Component

Weight

MT/day Wt %

H2O 71.1 99.72%

Urea 0.1 0.14%

NH3 0.1 0.14%


Temperature 112 °C

Pressure 0.55 bar

Component

Weight

MT/day Wt %

Urea 1060.1 93.00%

H2O 79.7 6.99%

NH3 0.1 0.01%


Temperature 110 °C

Pressure 2 bar

Component

Weight

MT/day Wt %

Urea 1060.0 99.20%

H2O 8.5 0.80%


Temperature 112 °C

Pressure 0.8 bar



5.1.12 Waste Water Treatment Unit

Component

Weight

MT/day Wt %

H2O 105.6 99.53%

Urea 0.3 0.28%

NH3 0.2 0.19%


Temperature 110 °C

Pressure 1 bar

Component

Weight

MT/day Wt %

H2O 223.9 99.73%

Urea 0.3 0.13%

NH3 0.3 0.13%


Temperature 110 °C

Pressure 1 bar

Component

Weight

MT/day Wt %

H2O 309.5 100.00%

Urea 0.0 0.00%

NH3 0.0 0.00%


Temperature 40 °C

Pressure 1 bar

Component

Weight

MT/day Wt %

H2O 20.0 94.79%

Urea 0.6 2.84%

NH3 0.5 2.37%


Temperature 129 °C

Pressure 2.6 bar

Waste Water

Treatment Unit



GRANULATION

SECTION

5.1.13 Granulator

Component

Weight

MT/day Wt %

Urea 720.8 99.20%

H2O 5.8 0.80%


Temperature 89 °C

Pressure 1 bar

Component

Weight

MT/day Wt %

Urea 1060.0 99.20%

H2O 8.5 0.80%


Temperature 112 °C

Pressure 2 bar

Component

Weight

MT/day Wt %

Urea 31.8 99.20%

H2O 0.3 0.80%


Temperature 52 °C

Pressure 1.5 bar

Component

Weight

MT/day Wt %

Urea 10.6 0.45%

H2O 0.1 0.00%

Air 2356.9 99.55%


Temperature 55 °C

Pressure 6 bar

Component

Weight

MT/day Wt %

Urea 1802.0 99.20%

H2O 14.5 0.80%


Temperature 90 °C

Pressure 1 bar

Component

Weight

MT/day Wt %

Air 2356.89 100.00%


Temperature 35 °C

Pressure 6 bar



5.1.14 Screen

Component

Weight

MT/day Wt %

Urea 1802.0 99.20%

H2O 14.5 0.80%


Temperature 89.5 °C

Pressure 1 bar

Component

Weight

MT/day Wt %

Urea 477.0 99.20%

H2O 3.8 0.80%



Pressure 1 bar

Component

Weight

MT/day Wt %

Urea 1081.2 99.20%

H2O 8.7 0.80%



Pressure 1 bar

Component

Weight

MT/day Wt %

Urea 243.8 99.20%

H2O 2.0 0.80%



Pressure 1 bar



5.1.15 Product Cooler

Component

Weight

MT/day Wt %

Urea 1081.2 99.20%

H2O 8.7 0.80%


Temperature 89 °C

Pressure 1 bar

Component

Weight

MT/day Wt %

Urea 1060.0 99.20%

H2O 8.5 0.80%


Temperature 60 °C

Pressure 1 bar

Component

Weight

MT/day Wt %

Urea 21.2 0.34%

H2O 0.2 0.00%

Air 6213.6 99.66%


Temperature 45 °C

Pressure 6 bar

Component

Weight

MT/day Wt %

Air 6213.62 100.00%


Temperature 35 °C

Pressure 6 bar



5.1.16 Bag Filter

Component

Weight

MT/day Wt %

Urea 31.8 0.37%

H2O 0.3 0.00%

Air 8570.5 99.63%


Temperature 52 °C

Pressure 6 bar

Component

Weight

MT/day Wt %

Air 8570.5 100.00%


Temperature 52 °C

Pressure 1 bar

Component

Weight

MT/day Wt %

Urea 31.8 99.07%

H2O 0.3 0.93%


Temperature 52 °C

Pressure 1 bar



CHAPTER 6

MATERIAL FLOW SHEET



Material Flow Sheet

Figure 6.1 Material Flow Sheet



CHAPTER 7

HEAT BALANCE CALCULATION



7.0 Heat Balance Calculation

7.1 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 (0C) 80 120 200

Cp (KJ/KgK) 1.26 1.36 1.56

Urea Liquid

T (0C) 80 120 200

Cp (KJ/KgK) 1.4 1.6 2.1



Urea Solid

T (0C) 27 77 127

Cp (KJ/KgK) 1.56 1.8 2.04

Water Liquid

T (0C) 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 + 3332c (1)

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

8.6 = a + 385b + 3852c (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 + 3602c (4)

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

2.44 = a + 480b + 4802c (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 + 3002c (7)

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

1.01 = a + 500b + 5002c (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 + 3532c (10)

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

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

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

a = 1.08 b = -2.77*10-3

c = 1.04*10-5



7.1.1 Reactor

Low pressure steam load at 5 bar pressure and 151.8 ºC for ammonia heating

/day

Medium pressure steam load at 13 bar and 191.6 ºC for ammonia heating

Q1

Q2 130 ºC

34 ºC

170 ºC

190 ºC

170 ºC

170 ºC

190 ºC

MPS

LPS

MPS

COND.

198.3°C

198.3°C



Urea formation heat by decomposing Ammonium Carbamate

Ammonium Carbamate production in the reactor

Ammonium Carbamate formation heat

Heat required for increasing raw materials to 190 ºC

Energy required to reactor

Medium pressure steam load at 15 bar and 198.3ºC for reactor heating



7.1.2 Stripper

Decomposition energy of Ammonium Carbamate

Heat released from Urea

Heat released from Ammonium Carbamate

Heat released from Water

MP

STEAM

COND.

178°C

190 °C

190°C

198.3 °C

110 °C

198.3 °C



Heat absorbed by Carbon Dioxide

Heat absorbed for Ammonia vaporization

Energy required for stripper

Medium pressure steam load at 13bar and 191.6 ºC for heating

7.1.3 Scrubber

153 °C 190 °C

189 °C

150 °C



Heat released from up flow

Heat released from down flow

Heat absorbed by Ammonia and Ammonium Carbamate

Energy loss



SC

STM


Formation energy of Ammonium Carbamate at 170 C

Heat absorbed by Ammonium Carbamate


170 °C

190 °C

170 °C

150 °C

153 °C

145 °C

151.8 °C



Heat absorbed by Ammonia

Condensation heat and sensible heat released by Ammonia

Heat released by Carbon Dioxide

Heat released from Carbamate condenser

Production of steam load at 5bar

Assume Cp of water at 145 C-150 C = 4.27 kJ/kg



7.1.5 High pressure decomposer



Heat released from Ammonium Carbamate


178 °C

157 °C

157 °C



Heat released by Ammonia


Energy loss

7.1.6 Low pressure decomposer

129 °C

129 °C

129 °C

157 °C

80°C

COND.

151.8

°C

151.8 °C

LPS







Condensation heat released by water vapour from WWTU


Heat released by Ammonia



Heat released by Carbon Dioxide

Energy required to reactor

Medium pressure steam load at 13 bar and 191.8 ºC for heating

Low pressure steam load at 5 bar and 151.8 ºC for heating

7.1.7 Low pressure absorber


CW

129 °C

129 °C



Condensation heat released by Ammonia

Heat released from LP Absorber

Cooling water requirement

7.1.8 High pressure absorber

Operating temperature calculation

157 °C

129 °C

150 °C




Condensation heat released by Ammonia

Energy loss due to reduce temperature

Energy released from HP Absorber

Heat released to heat output from LPD

Heat released to cooling water

Cooling water requirement



7.1.9 Flash separator


Heat released from water

Heat absorbed by water vaporization

Heat loss

Heat required for slurry heat to 178 C

110 °C

178 °C

Urea slurry

110 °C

191.8

°C MPS

140°C

150 °C

129°C

COND.

191.8

°C

150 °C



Heat recovered from MP Absorber

Additional heat required by 13bar MP steam

MP steam load

7.1.10 Lower separator


Energy loss

110 °C

151.8 °C

COND.

LPS

110°C

110 °C

151.8 °C



Total energy requirement

5bar LP steam load

7.1.11 Upper separator


Heat absorbed by urea and water

112 °C

151.8 °C

COND.

LPS

112 °C

110 °C

151.8 °C



Energy loss

Total energy requirement

5bar LP steam load

7.1.12 Process wastewater treatment unit

Heat requirement of WWTU

Low pressure steam load at 5 bar and 151.8 ºC for heating

Cooling heat of process wastewater from flash separator

Cooling water load

Cooling heat of process wastewater from lower and upper separator

Cooling water load



7.2 Granulation Plant

7.2.1 Granulator

Heat removed from granulator

6 bar cooling Air load

7.2.2 Product cooler

Heat removed from Product cooler

6 bar cooling Air load



CHAPTER 8

TABULATED HEAT BALANCE



8.0 Tabulated heat balance

8.1 Tabulated Heat Balance

Input Energy MJ/day

Heating of Ammonia due to low pressure steam 471962.08

Heating of Ammonia due to high pressure steam 300428.45

Heat supplied to Reactor 899260.67

Heat supplied to Stripper 123475.64

Heat supplied to LPD by low pressure steam 104259.64

Heat supplied to LPD by high pressure steam 97492.80

Heat supplied to Flash Separator 172190.9

Heat supplied to Lower Separator 416783.04

Heat supplied to Upper separator 199581.49

Heat supplied to Wastewater Treatment Plant 63000.50

Total input energy 2848435.21

Output Energy MJ/day

Heat out from Scrubber 124.70

Heat out from Carbamate condenser 1255586.69

Heat out from HPD 6596.25

Heat out from LP Absorber 570330.38

Heat out from HP Absorber 251197.87

Heat out from Wastewater cooling 1 255948.00

Heat out from Wastewater cooling 2 512283.2

Heat out from Granulator 47434.75

Heat out from Product Cooler 62527.63

Total output energy 2962029.47

Table 8.1 Tabulated Heat Balance



Difference between input and output energy = 113594.26 MJ/day

Total heat output greater than the total heat input. 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

happens because of the heat losses occurred during the process.



REFERENCES

Book References

Urea manufacturing processes in Ullmann's Encyclopedia of Industrial Chemistry, 5th

Edition, Volume A27

Perry's Chemical Engineers' Handbook - Perry, R.H. and Green, D.W. (Editors)

MARTYN S. RAY; DAVID W. JOHNSTON - Chemical Engineering Design Project: A

Case Study Approach

World Wide Web references

Ammonia and Urea Production -

http://www.nzic.org.nz/ChemProcesses/production/1A.pdf

Urea - http://www.stamicarbon.com/urea/_en/index.htm

Urea - www.epa.gov/ttn/chief/ap42/ch08/final/c08s02.pdf

Urea Production and Manufacturing process

www.icis.com/v2/chemicals/9076560/urea/process.html

Urea – Wikipedia, the free encyclopedia - en.wikipedia.org/wiki/Urea

Fertilizer Urea - www.extension.umn.edu/distribution/cropsystems/DC0636.html

UREA - www.jtbaker.com/msds/englishhtml/u4725.htm

Urea - www.3rd1000.com/urea/urea.htm

MSDS safety data sheets for ammonium carbamate, urea, and ammonium from

http://msds.chem.ox.ac.uk/

MSDS urea - http://www.sciencestuff.com/msds/C2950.html - Science Stuff Inc.,1104

Newport Ave, Austin, TX, USA

MSDS urea - http://www.pusri.co.id/data/MSDS-urea.PDF

E-book References

The Environmental Impact of a Stamicarbon 2000 mtpd Urea Plant - Authors: Will

Lemmen (Licensing Manager) and Hans van Baal (Licensing Manager)

Latest Urea Technology for Improving Performance and Product Quality by EIJI

SAKATA (Senior Process Engineer),TAKAHIRO YANAGAWA (PROCESS ENGINEER) ---

TOYO ENGINEERING CORPORATION , TOKYO JAPAN

Escalating worldwide use of urea – a global change contributing to coastal

eutrophication by PATRICIA M. GLIBERT, JOHN HARRISON, CYNTHIA HEIL and

SYBIL SEITZINGER

NH3

TCW

c

g

e

Steam

Cond.

h

TCW

i

CW

j

Steam

Cond.

k

l

m

Water

Urea melt to granulation

CO2

a

b

d

a) CO2 compressorb) Hydrogen removal reactorc) Urea reactord) High-pressure strippere) High-pressure carbamate condenserf) High-pressure scrubberg) Low-pressure absorberh) Low-pressure decomposer and rectifieri) Pre-evaporatorj) Low-pressure carbamate condenserk) Evaporatorl) Vacuum condensation sectionm) Process condensate treatmentCW - Cooling waterTCW - Tempered cooling water

Stamicarbon CO2 - Stripping Urea Process

ff

Steam

Cond.

NH3

CO2

Water

Air

Urea

a

b

cd

e

f

g h

i

j

Convectional Urea Plant

a) CO2 compressor; b) High pressure ammonia pump; c) Urea reactor; d) Medium-pressure decomposer;e) Ammonia carbamate separation column; f) Low-pressure decomposer; g) Evaporator; h) Prilling;

i) Desorber (waste water stripper); j) Vacuum condensation section

Garden

Administration section

Process area

Granualization area

Cooling tower

Ammonia storage

tank

CO2 Storage

tank

Urea store house

Waste water treatment plant

Cooling towerWater tank

Fuel tanks

Gua

rd ro

om

pond

Gua

rd ro

om

REACTOR

SCRUBBER

CARBAMATE CONDENSER

STRIPPER

LPD

HPD

COMPRESSOR

NH3

CO2

MP STEAM

COND.

UREA GRANULES

AIR

AIR

GRANULATION SECTION

SURFACE CONDENCER

SC

STM

HPABSORBER

FLASH SEPARATOR

LP ABSORBER

LOWERSEPARATOR

UPPERSEPARATOR

STM

SC

CW

CWUPC

PC STRIPPER

HYDROLYSER

Clean gas out

BAG FILTER

MP steam

LP steam

CW

CW

NH3 CO2

MP STEAM

COND.

UREA GRANULES

AIR

GRANULATION SECTION

SURFACE CONDENCER

SC

STM

HPABSORBER

FLASH SEPARATOR

LP ABSORBER

LOWERSEPARATOR

UPPERSEPARATOR

CW

CW

Waste water

PC STRIPPER

HYDROLYSER

P

COMPRESSOR

MP steam

LP steam

Clean gas out

BAG FILTER

STRIPPER

Feed Water

FIRE TUBE BOILER

CO2

CW

CW

CONDENSED WATER TANKS

COOLING TOWER

POND

T

T

T

T

WATER

T

T

T

TT

T

T

T

Urea flow linesother process linesSteam lineCondensed water lineCooling water line

MT/day Wt %1802 99.20%

Componeng

MT/day Wt % 14.5 0.80%g

MT/day Wt %

NH3 1.4 12.79% 1816.5 MT/day 31.8 99.20%Weight MT/day Wt %

CO2 9.7 87.21%Weight MT/day Wt %

Weight MT/day Wt % 90 °C 0.3 0.80% 31.8 0.37%

Flow rate 11.2 MT/day 1060.6 75.81% 1060.3 82.00% Pressure 1 bar 32.1 MT/day 0.3 0.00%Temperatu 189 °C 338 24.16% 232.4 17.98% 52 °C 8570.5 99.63%

Pressure 175 barWeight MT/day Wt % 0.5 0.04% 0.3 0.02% Pressure 1.5 bar 8602.6 MT/day

327.3 79.49% 1399.1 MT/day 1293 MT/day 52 °C84.5 20.51% 129 °C 110 °C Pressure 6 bar

Flow rate 411.7 MT/day Pressure 2.5 bar Pressure 0.7 bar157 °C

ComponenWeight Wt % Pressure 17.5 bar Weight Wt %NH3 53.1 28.89% 1060 99.20%

Component Weight Wt % Carbamate 130.7 71.11% 8.5 0.80% Weight Wt %

UreaH2O

NH3ComponentNH3

CO2

Temperature

Component

UreaH2O

NH3

Flow rateTemperature


Component

ComponentUreaH2O Component

Component

Urea

H2O



Urea

H2O

Flow rate

Temperature

Component

Component

Urea

H2OAir

SCRUBBER

FLASHSEPARATOR

GRANULATOR

BAG FILTER

CO2 263.3 100.00% Flow rate 183.8 MT/day 1068.5 MT/day 720.8 99.20%Flow rate 263.3 MT/day Temperatu 150 °C 112 °C 5.8 0.80%Temperature 170 °C Pressure 175 bar Pressure 2 bar 726.6 MT/day

Pressure 175 barWeight MT/day Wt % 89 °C

ComponenWeight MT/day Wt % 1060 59.00% Pressure 1 bar

NH3 212.3 28.89% MT/day Wt % 349.4 19.45% MT/day Wt %Weight Wt % Carbamate 522.7 71.11% Urea 1060 48.00% 69.3 3.85% 1060.1 93.00%

4.8 12.79% Flow rate 735.1 MT/day 499.1 22.60% 318 17.70% 79.7 6.99%Weight MT/day Wt %

Weight MT/day Wt %

32.4 87.21% Weight Wt % Temperatu 150 °C NH3 331.3 15.00% 1796.6 MT/day 0.1 0.01% 10.6 0.45% 21.2 0.34%37.2 MT CO2 263.3 100.00% Pressure 175 bar H2O 318 14.40% 157 °C 1139.9 MT/day 0.1 0.00% 0.2 0.00%190 °C Flow rate 263.3 MT/day 2208.3 MT/day Pressure 17.5 bar Temperature 110 °C 2356.9 99.55% 6213.6 99.66%175 bar 170 °C 178 °C Pressure 0.7 bar 2367.6 MT/day 6235 MT/day

175 bar 175 bar 55 °C 45 °CPressure 6 bar Pressure 6 bar

Weight MT/day Wt %

MT/day Wt % MT/day Wt % 1081.2 99.20%NH3 486.1 23.76% ComponenWeight Wt % Weight Wt % 1060.6 75.81% 8.7 0.80%

1559.7 76.24% NH3 612.4 44.89% 9.5 1.91% 338 24.16% 1089.9 MT/dayFlow rate 2045.9 MT/day CO2 751.8 55.11% 486.4 98.09% 0.5 0.04% 89 °C

Component

NH3CO2


Pressure

Component

TemperaturePressure

Component

A. Carbamate

Temperature

Carbamate

Flow rateTemperaturePressure

Component

UreaCarbamate NH3

H2OFlow rate

Component ComponentUrea

H2O

ComponentNH3

Carbamate

ComponentUreaH2ONH3


NH3

Flow rate

UreaH2OFlow rate

Temperature

ComponentUreaH2OAirFlow rateTemperature

ComponentUreaH2OAirFlow rateTemperature

ComponentUreaH2OFlow rateTemperature

CARBAMATECONDENSER

LPD

HPD

UPPER SEPARATO

R

LOWER SEPARATOR

SCREEN

PRODUCT

COOLER

Flow rate 2045.9 MT/day 2 751.8 55.11% 486.4 98.09% 0.5 0.04% 89 C170 °C Flow rate 1364.3 MT/day 495.9 MT/day 1399.1 MT/day Pressure 1 bar

175 bar Temperatu 190 °C 129 °C 129 °CWeight MT/day Wt % Component

Weight MT/day

Pressure 175 bar Pressure 1.5 bar Pressure 2.5 bar 20 94.79% Urea 10600.6 2.84% H2O 8.50.5 2.37% Flow rate 1068.5

21.1 MT/day Temperature 60129 °C Pressure 1

Pressure 2.6 bar

ComponentWeight MT/day Wt %

Urea 1060 36.90%Component Weight Wt % Carbamate 591 20.57%NH3 600.7 100.00% NH3 903.6 31.46%

Flow rate 600.7 MT/day H2O 318 11.07%Weight MT/day Wt %

Weight MT/day Wt %

Temperature 170 °C Flow rate 2872.6 MT/dayWeight MT/day Wt % 223.9 99.73% 309.5 100.00%

175 bar 190 °C CO2 263.3 100.00% 0.3 0.13% 0 0.00%

175 bar Flow rate 263.3 MT/dayWeight MT/day Wt % 0.3 0.13% 0 0.00%

170 °C 105.6 99.53% 224.5 MT/day 309.5 MT/dayht

Pressure

Wt %99.20%0.80%

MT/day°Cbar

Component

Temperature

Temperature

Pressure

Temperature

Pressure

Flow rate

Temperature

CarbamateFlow rate

Temperature

NH3

Component

H2OUrea

NH3

Flow rateComponentH2O Flow rate


Component

H2OUrea

NH3

ComponentH2OUreaNH3

TemperatureREACTOR

STRIPPERHP

ABSORBER

LP ABSORBER

175 barht MT/d Wt % 0.3 0.28% 110 °C 40 °C

CO2 77.3 100.00% 0.2 0.19% Pressure 1 bar Pressure 1 barFlow rate 77.3 MT 106.1 MT/day

80 °C 110 °C20 bar Pressure 1 bar

Component

Temperature

Pressure

Pressure

NH3


TemperatureUrea TemperatureWWTP UNIT

CO2

COMPRESSOR

urea final report

Documents

urea fertilizer

tons of urea

urea demand

solid urea

urea imports

sri lanka urea

sapugaskanda urea plant

urea manufacturing ammonia