Urea Manufacturing Plant: CH 4200 - Comprehensive Design Project
Urea Manufacturing Plant: CH 4200 - Comprehensive Design Project
Urea Manufacturing Plant: CH 4200 - Comprehensive Design Project
PLANT
CH 4200 – Comprehensive Design Project
Project Coordinator:
Dr. Maneesha Gunasekara
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
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
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
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.
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
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
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
5.1.3 Carbamate Condenser……………………………………………… 68
5.1.4 Scrubber…………………………………………………………… 69
5.1.5 High Pressure Decomposer………………………………...……… 70
5.1.6 Low Pressure Decomposer ………………………………………… 71
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
7.1.4 Carbamate Condenser……………………………………………… 93
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
VII
Urea Manufacturing Plant
CHAPTER 1
LITERATURE SURVEY
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:
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.
Boiling point NA
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 (NH 4)+ 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.
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.
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.
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:
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.
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.
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.
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.
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-
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.
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.
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.
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.
350000
300000
Quantity (MT)
250000
200000
150000
100000
50000
0
1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007
Year
UREA IMPORTS
14000
Total Cost in Rs Millions
12000
10000
8000
6000
4000
2000
0
1997 1999 2000 2001 2002 2004 2005 2006 2007
Year
Figure 1.4 Urea import data
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.
Comprehensive design project
16
Urea Manufacturing Plant Chapter 02
CHAPTER 2
PROCESS SELECTION AND
ECONOMIC ASPECTS
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 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
Comprehensive design project
20
Urea Manufacturing Plant Chapter 02
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.
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.
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.
High environment
pollution
Stamicarbon CO2 – Has high urea yield per High production cost
stripping process pass
High energy cost
High purity
Low environment
pollution
High efficiency
Among above urea manufacturing processes, ACES process is selected because of it has
following advantages compared to other processes
CHAPTER 3
PROCESS DESCRIPTION AND
FLOW SHEET
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 CO 2 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.
3.2.2 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 CO 2 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.
Comprehensive design project
34
Urea Manufacturing Plant Chapter 03
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.
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.
CHAPTER 4
SITE SELECTION
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
Comprehensive design project
43
Urea Manufacturing Plant Chapter 04
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
Emission Media
Substance To
To Water Via Solid Waste
Atmosphere
Ammonia
Formaldehyde
Methanol
Total Nitrogen
Particulate Matter (PM10)
Volatile Organic
Compounds(VOCs)
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
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.
Flammability
Urea is non-flammable material
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
Comprehensive design project
50
Urea Manufacturing Plant Chapter 04
algal blooms to produce toxins, and urea in runoff from fertilizers may play a role in the increase
of toxic blooms.
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.
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.
Hazard identification
Irritating or corrosive to exposed tissues. Inhalation of vapors may result in pulmonary edema
and chemical pneumonitis
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.
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.
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".
Disposal Considerations
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.
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.
Flash point: Not applicable
Flammability limits: Not applicable
Auto-ignition temperature: not applicable
Hazard identification
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.
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.
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.
Disposal Considerations
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.
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...).
Hazard identification
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
Fire Extinguisher
Small fire: Use dry chemical powder.
Large fire: Use water spray, fog or foam. Do not use water jet.
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
5.1.1 Reactor
Weight
Component MT/day Wt %
NH3 4.8 12.79%
CO2 32.4 87.21%
Flow rate 37.2 MT
Temperature 190 °C
Pressure 175 bar
Weight
Component MT/day Wt %
CO2 263.3 100.00%
Flow rate 263.3 MT/day
Temperature 170 °C
Pressure 175 bar
Weight
Component MT/day Wt %
NH3 486.1 23.76%
A. Carbamate 1559.7 76.24%
Flow rate 2045.9 MT/day
Temperature 170 °C
Pressure 175 bar
Weight
Component MT/day Wt %
Urea 1060.0 36.90%
Carbamate 591.0 20.57%
Weight NH3 903.6 31.46%
Component MT/day Wt %
H2O 318.0 11.07%
NH3 600.7 100.00% Flow rate 2872.6 MT/day
Flow rate 600.7 MT/day Temperature 190 °C
Temperature 170 °C Pressure 175 bar
Pressure 175 bar
5.1.2 Stripper
Weight
Component MT/day Wt %
NH3 612.4 44.89%
Weight
Component MT/day Wt % CO2 751.8 55.11%
Urea 1060.0 36.90% Flow rate 1364.3 MT/day
Carbamate 591.0 20.57% Temperature 190 °C
Pressure 175 bar
NH3 903.6 31.46%
H2O 318.0 11.07%
Flow rate 2872.6 MT/day
Temperature 190 °C
Pressure 175 bar
MP
STEAM
COND.
Weight
Component MT/day Wt %
Urea 1060.0 48.00%
Weight Carbamate 499.1 22.60%
Component MT/day Wt % NH3 331.3 15.00%
CO2 700.0 100.00% H2O 318.0 14.40%
Flow rate 700.0 MT Flow rate 2208.3 MT/day
Temperature 110 °C Temperature 178 °C
Pressure 175 bar Pressure 175 bar
Weight
Component MT/day Wt %
NH3 612.4 44.89%
Weight
Component MT/day Wt % CO2 751.8 55.11%
Flow rate 1364.3 MT/day
NH3 56.4 26.89%
Temperature 190 °C
CO2 22.7 10.82% Pressure 175 bar
Carbamate 130.7 62.29%
Flow rate 209.8 MT/day
Temperature 153 °C
Pressure 175 bar
STM
Weight
Component MT/day Wt %
NH3 212.3 28.89%
Carbamate 522.7 71.11%
SC Flow rate 735.1 MT/day
Temperature 150 °C
Pressure 175 bar
Weight
Component MT/day Wt %
Weight
CO2 263.3 100.00% Component MT/day Wt %
Flow rate 263.3 MT
CO2 263.3 14.44%
Temperature 170 °C
Carbamate 1559.7 85.56%
Pressure 175 bar
Flow rate 1823.0 MT/day
Temperature 170 °C
Pressure 175 bar
5.1.4 Scrubber
Weight
Component MT/day Wt %
NH3 1.4 12.79%
CO2 9.7 87.21%
Flow rate 11.2 MT/day
Temperature 189 °C
Pressure 175 bar
Weight
Component MT/day Wt %
NH3 53.1 28.89%
Carbamate 130.7 71.11%
Flow rate 183.8 MT/day
Temperature 150 °C
Pressure 175 bar
Weight
Component MT/day Wt %
Weight NH3 56.4 26.89%
Component MT/day Wt % CO2 22.7 10.82%
NH3 4.8 12.79% Carbamate 130.7 62.29%
CO2 32.4 87.21% Flow rate 209.8 MT/day
Flow rate 37.2 MT Temperature 153 °C
Temperature 190 °C Pressure 175 bar
Pressure 175 bar
Weight
Component MT/day Wt %
NH3 327.3 79.49%
CO2 84.5 20.51%
Flow rate 411.7 MT/day
Temperature 157 °C
Pressure 17.5 bar
Weight
Component MT/day Wt %
Urea 1060.0 48.00%
Carbamate 499.1 22.60% Weight
NH3 331.3 15.00% Component MT/day Wt %
Urea 1060 59.00%
H2O 318.0 14.40%
Carbamate 349.4 19.45%
Flow rate 2208.3 MT/day
Temperature 178 °C NH3 69.3 3.85%
Pressure 175 bar H2O 318.0 17.70%
Flow rate 1796.6 MT/day
Temperature 157 °C
Pressure 17.5 bar
Weight
Weight Component MT/day Wt %
Component MT/day Wt % NH3 221.5 44.67%
Urea 1060 59.00% CO2 274.4 55.33%
Carbamate 349.4 19.45% Flow rate 495.9 MT/day
NH3 69.3 3.85% Temperature 129 °C
H2O 318.0 17.70% Pressure 2.5 bar
Flow rate 1796.6 MT/day
Temperature 157 °C
Pressure 17.5 bar
Weight
Component MT/day Wt %
H2O 20 94.79%
Urea 0.6 2.84%
NH3 0.5 2.37%
Flow rate 21.1 MT/day
Temperature 129 °C
Pressure 2.6 bar
Weight
Component MT/day Wt %
Weight Urea 1060.6 75.81%
Component MT/day Wt % H2O 338.0 24.16%
CO2 77.3 100.00% NH3 0.5 0.04%
Flow rate 77.3 MT Flow rate 1399.1 MT/day
Temperature 80 °C Temperature 129 °C
Pressure 20 bar Pressure 2.5 bar
Weight
Component MT/day Wt %
NH3 221.5 44.67%
CO2 274.4 55.33%
Flow rate 495.9 MT/day
Temperature 129 °C
Pressure 2.5 bar
CW
Weight
Component MT/day Wt %
NH3 9.5 1.91%
Carbamate 486.4 98.09%
Flow rate 495.9 MT/day
Temperature 129 °C
Pressure 1.5 bar
Weight
Component MT/day Wt %
NH3 328.7 77.73%
CO2 94.2 22.27%
Flow rate 422.9 MT/day
Temperature 151 °C
Pressure 17.5 bar
Weight
Component MT/day Wt %
NH3 9.5 1.91%
Carbamate 486.4 98.09%
Flow rate 495.9 MT/day
Temperature 129 °C
Pressure 17.5 bar
Weight
Component MT/day Wt %
NH3 265.4 28.89%
CO2 0.0 0.00%
Carbamate 653.4 71.11%
Flow rate 918.8 MT/day
Temperature 150 °C
Pressure 12 bar
Weight
Component MT/day Wt %
H2O 105.6 99.53%
Urea 0.3 0.28%
NH3 0.2 0.19%
Flow rate 106.1 MT/day
Temperature 190 °C
Pressure 0.55 bar
Weight
Component MT/day Wt %
Urea 1060.6 75.81%
H2O 338.0 24.16%
NH3 0.5 0.04%
Flow rate 1399.1 MT/day
Temperature 178 °C Weight
Pressure 2.5 bar Component MT/day Wt %
Urea 1060.3 82.00%
H2O 232.4 17.98%
NH3 0.3 0.02%
Flow rate 1293.0 MT/day
Temperature 110 °C
Pressure 0.7 bar
Weight
Component MT/day Wt %
H2O 152.8 99.74%
Urea 0.2 0.13%
NH3 0.2 0.13%
Flow rate 153.2 MT/day
Temperature 110 °C
Pressure 0.55 bar
Weight
Component MT/day Wt %
Urea 1060.3 82.00%
H2O 232.4 17.98%
NH3 0.3 0.02%
Flow rate 1293.0 MT/day
Temperature 110 °C
Pressure 2 bar
Weight
Component MT/day Wt %
Urea 1060.1 93.00%
H2O 79.7 6.99%
NH3 0.1 0.01%
Flow rate 1139.9 MT/day
Temperature 110 °C
Pressure 0.7 bar
Weight
Component MT/day Wt %
H2O 71.1 99.72%
Urea 0.1 0.14%
NH3 0.1 0.14%
Flow rate 71.3 MT/day
Temperature 112 °C
Pressure 0.55 bar
Weight
Component MT/day Wt %
Urea 1060.1 93.00%
H2O 79.7 6.99%
NH3 0.1 0.01%
Flow rate 1139.9 MT/day
Temperature 110 °C
Pressure 2 bar
Weight
Component MT/day Wt %
Urea 1060.0 99.20%
H2O 8.5 0.80%
Flow rate 1068.5 MT/day
Temperature 112 °C
Pressure 0.8 bar
Weight
Component MT/day Wt %
Weight H2O 223.9 99.73%
Component MT/day Wt %
Urea 0.3 0.13%
H2O 105.6 99.53%
NH3 0.3 0.13%
Urea 0.3 0.28%
Flow rate 224.5 MT/day
NH3 0.2 0.19% Temperature 110 °C
Flow rate 106.1 MT/day Pressure 1 bar
Temperature 110 °C
Pressure 1 bar
Waste Water
Treatment Unit
Weight
Component MT/day Wt %
Weight H2O 309.5 100.00%
Component MT/day Wt % Urea 0.0 0.00%
H2O 20.0 94.79% NH3 0.0 0.00%
Urea 0.6 2.84% Flow rate 309.5 MT/day
NH3 0.5 2.37% Temperature 40 °C
Flow rate 21.1 MT/day Pressure 1 bar
Temperature 129 °C
Pressure 2.6 bar
5.1.13 Granulator
Weight
Component MT/day Wt %
Urea 720.8 99.20%
H2O 5.8 0.80%
Flow rate 726.6 MT/day
Temperature 89 °C
Pressure 1 bar
Weight Weight
Component MT/day Wt % Component MT/day Wt %
Urea 31.8 99.20% Urea 10.6 0.45%
H2O 0.3 0.80% H2O 0.1 0.00%
Flow rate 32.1 MT/day
Air 2356.9 99.55%
Temperature 52 °C
Flow rate 2367.6 MT/day
Pressure 1.5 bar
Temperature 55 °C
Pressure 6 bar
GRANULATION
SECTION
Weight Weight
Component MT/day Wt % Component MT/day Wt %
Urea 1060.0 99.20% Urea 1802.0 99.20%
H2O 8.5 0.80% H2O 14.5 0.80%
Flow rate 1068.5 MT/day Flow rate 1816.5 MT/day
Temperature 112 °C Temperature 90 °C
Pressure 2 bar Pressure 1 bar
Weight
Component MT/day Wt %
Air 2356.89 100.00%
Flow rate 2356.89 MT/day
Temperature 35 °C
Pressure 6 bar
5.1.14 Screen
Weight
Component MT/day Wt %
Urea 1802.0 99.20%
H2O 14.5 0.80%
Weight
Flow rate 1816.5 MT/day
Component MT/day Wt %
Temperature 89.5 °C
Urea 477.0 99.20%
Pressure 1 bar
H2O 3.8 0.80%
Flow rate 480.8 MT/day
Temperature 89.5 °C
Pressure 1 bar
Weight
Component MT/day Wt %
Weight Urea 1081.2 99.20%
Component MT/day Wt %
H2O 8.7 0.80%
Urea 243.8 99.20%
Flow rate 1089.9 MT/day
H2O 2.0 0.80%
Temperature 89.5 °C
Flow rate 245.8 MT/day Pressure 1 bar
Temperature 89.5 °C
Pressure 1 bar
Weight
Weight Component MT/day Wt %
Component MT/day Wt % Urea 21.2 0.34%
Urea 1081.2 99.20% H2O 0.2 0.00%
H2O 8.7 0.80% Air 6213.6 99.66%
Flow rate 1089.9 MT/day Flow rate 6235.0 MT/day
Temperature 89 °C Temperature 45 °C
Pressure 1 bar Pressure 6 bar
Weight
Component MT/day Wt %
Urea 1060.0 99.20%
Weight
Component MT/day Wt % H2O 8.5 0.80%
Air 6213.62 100.00% Flow rate 1068.5 MT/day
Flow rate 6213.62 MT/day Temperature 60 °C
Temperature 35 °C Pressure 1 bar
Pressure 6 bar
Weight
Component MT/day Wt %
Air 8570.5 100.00%
Flow rate 8570.5 MT/day
Temperature 52 °C
Pressure 1 bar
Weight
Component MT/day Wt %
Urea 31.8 0.37%
H2O 0.3 0.00%
Air 8570.5 99.63%
Flow rate 8602.6 MT/day
Weight Temperature 52 °C
Component MT/day Wt % Pressure 6 bar
Urea 31.8 99.07%
H2O 0.3 0.93%
Flow rate 32.1 MT/day
Temperature 52 °C
Pressure 1 bar
CHAPTER 6
MATERIAL FLOW SHEET
CHAPTER 7
HEAT BALANCE CALCULATION
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
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
190 ºC
MPS 170 ºC
198.3°C
COND.
198.3°C
170 ºC
170 ºC
MPS Q2
130 ºC
LPS 190 ºC
Q1
34 ºC
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
Medium pressure steam load at 15 bar and 198.3ºC for reactor heating
7.1.2 Stripper
190 °C
190°C
MP
STEAM
198.3 °C
COND.
198.3 °C
178°C
110 °C
7.1.3 Scrubber
189 °C
150 °C
153 °C
190 °C
Energy loss
150 °C
153 °C
STM 190 °C
151.8 °C
145 °C
SC
170 °C
170 °C
157 °C
178 °C
157 °C
Energy loss
129 °C
157 °C
LPS
151.8 °C
129 °C
COND.
151.8
°C
129 °C
80°C
129 °C
CW
129 °C
157 °C
129 °C
150 °C
110 °C
191.8
150 °C °C
MPS
Urea slurry
129°C 140°C
178 °C
150 °C COND.
191.8
°C
110 °C
Heat loss
MP steam load
110 °C
LPS
151.8 °C
151.8 °C
COND.
110 °C
Energy loss
112 °C
110 °C
LPS
151.8 °C
151.8 °C
COND.
112 °C
Energy loss
CHAPTER 8
TABULATED HEAT BALANCE
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
l
e
CW
Steam m
h i
ff j
TCW
Water
TCW
Cond.
a) CO2 compressor
b) Hydrogen removal reactor
c NH3 c) Urea reactor
d) High-pressure stripper
e) High-pressure carbamate condenser
f) High-pressure scrubber
g) Low-pressure absorber
h) Low-pressure decomposer and rectifier
i) Pre-evaporator k
j) Low-pressure carbamate condenser
Steam k) Evaporator Steam
l) Vacuum condensation section
m) Process condensate treatment
CW - Cooling water
Cond.
TCW - Tempered cooling water
b
CO2
Cond.
d
NH3
e
c
d
Water
g h
CO2 a
Air
b
Urea
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
Fuel tanks pond
Ammonia
storage
tank
Process area
Garden
Waste water
treatment plant
CO2
Guard room
Storage
tank
Cooling Cooling
tower Water tank tower
STM Clean
SCRUBBER gas out
SC
BAG
FILTER
CARBAMATE UPPER
CONDENSER LOWER SEPARATOR
SEPARATOR
LPD
STM
HPD
SC
REACTOR
LP
HP ABSORBER GRANULATION
ABSORBER SECTION
STRIPPER SURFACE
CW PC STRIPPER
CW CONDENCER
UREA
MP CW AIR GRANULES
STEAM
CW AIR
MP UPC HYDROLYSER
steam COND.
LP
steam
COMPRESSOR
NH3
CO2
Urea flow lines
other process lines
Steam line Clean
Condensed water line gas
Cooling water line out
BAG
FILTER
T
FLASH
SEPARATOR
T LOWER T UPPER
SEPARATOR SEPARATOR
T
P STM
T
GRANULATION
SC SECTION
CO2
SURFACE
CONDENCER
LP
UREA
ABSORBER
T HP GRANULES
T
ABSORBER
STRIPPER PC
T CW
MP CW STRIPPER T
STEAM CW HYDROLYSER
MP T
Waste
steam COND. water T AIR
CW
T
LP
steam
Feed
Water
POND
NH3 CO2 COOLING
TOWER WATER
Component MT/day Wt %
g Urea 1802 99.20% g
ComponenMT/day Wt % H2O 14.5 0.80% Component MT/day Wt %
Weight
NH3 1.4 12.79% Flow rate 1816.5 MT/day Urea 31.8 99.20% Component MT/day Wt %
Weight Weight
CO2 9.7 87.21% Component MT/day Wt % FLASH Component MT/day Wt % Temperature 90 °C H2O 0.3 0.80% Urea 31.8 0.37%
SEPARATOR BAG
Flow rate 11.2 MT/day Urea 1060.6 75.81% Urea 1060.3 82.00% Pressure 1 bar Flow rate 32.1 MT/day H2O 0.3 0.00%
FILTER
Temperatu 189 °C H2O 338 24.16% H2O 232.4 17.98% Temperature 52 °C Air 8570.5 99.63%
Weight
Pressure 175 bar Component MT/day Wt % NH3 0.5 0.04% NH3 0.3 0.02% Pressure 1.5 bar Flow rate 8602.6 MT/day
NH3 327.3 79.49% Flow rate 1399.1 MT/day Flow rate 1293 MT/day Temperature 52 °C
CO2 84.5 20.51% Temperature 129 °C Temperature 110 °C GRANULATOR Pressure 6 bar
Flow rate 411.7 MT/day Pressure 2.5 bar Pressure 0.7 bar
Temperature 157 °C
ComponenWeight Wt % Pressure 17.5 bar Component Weight Wt %
SCRUBBE
NH3 53.1 28.89% Urea 1060 99.20%
R
Component Weight Wt % Carbamate 130.7 71.11% H2O 8.5 0.80% Component Weight Wt %
CO2 263.3 100.00% Flow rate 183.8 MT/day Flow rate 1068.5 MT/day Urea 720.8 99.20%
Flow rate 263.3 MT/day Temperatu 150 °C LOWER Temperature 112 °C H2O 5.8 0.80% PRODUC
SEPARATOR T
Temperature 170 °C Pressure 175 bar HPD Pressure 2 bar Flow rate 726.6 MT/day
Weight COOLER
Pressure 175 bar Component MT/day Wt % Temperature 89 °C
Weight
ComponenMT/day Wt % Urea 1060 59.00% LPD Pressure 1 bar
NH3 212.3 28.89% Component MT/day Wt % Carbamate 349.4 19.45% Component MT/day Wt %
Component Weight Wt % Carbamate 522.7 71.11% Urea 1060 48.00% NH3 69.3 3.85% Urea 1060.1 93.00%
Weight Weight
NH3 4.8 12.79% Flow rate 735.1 MT/day Carbamate 499.1 22.60% H2O 318 17.70% H2O 79.7 6.99% SCREEN Component MT/day Wt % Component MT/day Wt %
CO2 32.4 87.21% Component Weight Wt % Temperatu 150 °C NH3 331.3 15.00% Flow rate 1796.6 MT/day NH3 0.1 0.01% Urea 10.6 0.45% Urea 21.2 0.34%
Flow rate 37.2 MT CO2 263.3 100.00% Pressure 175 bar H2O 318 14.40% Temperature 157 °C Flow rate 1139.9 MT/day H2O 0.1 0.00% H2O 0.2 0.00%
Temperature 190 °C Flow rate 263.3 MT/day Flow rate 2208.3 MT/day Pressure 17.5 bar Temperature 110 °C Air 2356.9 99.55% Air 6213.6 99.66%
Pressure 175 bar Temperature 170 °C CARBAMATE Temperature 178 °C Pressure 0.7 bar Flow rate 2367.6 MT/day Flow rate 6235 MT/day
CONDENSER
Pressure 175 bar Pressure 175 bar Temperature 55 °C Temperature 45 °C
Pressure 6 bar Pressure 6 bar
UPPER Weight
SEPARATO Component MT/day Wt %
Component MT/day Wt % Component MT/day Wt % R Urea 1081.2 99.20%
NH3 486.1 23.76% ComponenWeight Wt % Component Weight Wt % Urea 1060.6 75.81% H2O 8.7 0.80%
A. Carbamate 1559.7 76.24% NH3 612.4 44.89% NH3 9.5 1.91% H2O 338 24.16% Flow rate 1089.9 MT/day
Flow rate 2045.9 MT/day CO2 751.8 55.11% Carbamate 486.4 98.09% NH3 0.5 0.04% Temperature 89 °C
C
REACTOR Temperature 170 °C Flow rate 1364.3 MT/day Flow rate 495.9 MT/day Flow rate 1399.1 MT/day Pressure 1 bar
Weight Weight
Pressure 175 bar Temperatu 190 °C Temperature 129 °C Temperature 129 °C Component MT/day Wt % Component MT/day Wt %
Pressure 175 bar Pressure 1.5 bar Pressure 2.5 bar H2O 20 94.79% Urea 1060 99.20%
Urea 0.6 2.84% H2O 8.5 0.80%
NH3 0.5 2.37% Flow rate 1068.5 MT/day
Flow rate 21.1 MT/day Temperature 60 °C
Temperature 129 °C Pressure 1 bar
Pressure 2.6 bar
Weight LP
STRIPPER ABSORBER
Component MT/day Wt % HP
ABSORB
Urea 1060 36.90%
ER
Component Weight Wt % Carbamate 591 20.57%
NH3 600.7 100.00% NH3 903.6 31.46%
Weight Weight
Flow rate 600.7 MT/day H2O 318 11.07% Component MT/day Wt % Component MT/day Wt %
Weight
Temperature 170 °C Flow rate 2872.6 MT/day Component MT/day Wt % H2O 223.9 99.73% H2O 309.5 100.00%
Pressure 175 bar Temperature 190 °C CO2 263.3 100.00% Urea 0.3 0.13% Urea 0 0.00%
Weight
Pressure 175 bar Flow rate 263.3 MT/day Component MT/day Wt % NH3 0.3 0.13% NH3 0 0.00%
Temperature 170 °C H2O 105.6 99.53% Flow rate 224.5 MT/day Flow rate 309.5 MT/day
ht
Pressure 175 bar Component MT/d Wt % Urea 0.3 0.28% Temperature 110 °C Temperature 40 °C
CO2 77.3 100.00% NH3 0.2 0.19% WWTP UNIT Pressure 1 bar Pressure 1 bar
Flow rate 77.3 MT Flow rate 106.1 MT/day
Temperature 80 °C Temperature 110 °C
Pressure 20 bar Pressure 1 bar
CO2
COMPRESSOR