The document describes the process for producing urea through a single reactor system with recovery and recycling capabilities. Ammonia and carbon dioxide are reacted in a reactor to form ammonium carbamate. This mixture is then sent to a stripper where the carbamate decomposes to urea. Unreacted gases are separated in a rectifying column and recycled to the reactor. The urea solution is concentrated in single and vacuum evaporators then prilled to form granular urea product that is 99% concentrated. The process aims to minimize costs through heat recovery and a single reactor system compared to previous two reactor methods.

1. Title page
Saad, Ali Raza, M.Ali, Usama
19-Dec-2016
NFC IEFR, FSD

2. Executive summary
Urea is to be prepared by NH3 and CO2 through ammonium
carbamate. NH3 and CO2 is passed through reactor. Where
ammonium carbamate is produced. Then ammonium carbamate
is moved to a stripper at low pressure and high temperature where
it decomposes to urea. Then urea formed is moved to rectifying
column where additional substances are removed from urea and
then urea is passed through single effect evaporator and them
vaccum evaporator. These evaporator will make the urea highly
concentrated. Then finally highly concentrated urea is moved to
prilling tower where granulars of urea is formed through seeding
process. The final product obtained is 99% concentrated urea.

3. Table of content
No. Topic page no.
1. Introduction .
2. Background .
3. Procedure .
a) Stripper .
b) Rectifying column .
C) BFD Diagram .
c) Cooling tower & scrubber .
d) Single effect evaporator .
e) Vacuum evaporator .
f) Periling tower .
4. Equipment .
5. Personnel .
6. Reference .

4. Introduction
 Urea is produced by CO2 and NH3. The purpose is to minimize the cost of
production of urea by installing only one reactor by changing the
temperaute and pressure. The quality of urea produced will be observed
and compared with two reactor system method. Morever rectifying column
is also installed which will separate the unreacted NH3 and CO2 from urea.
NH3 and CO2 will be recycle back to reactor so that more quantity of
ammonia can be produced. Heat produced from the reactions will be
recovered up to maximum extent by using Combination (combi) Boiler
which is latest boiler.

5. Background
 Recently urea was prepared with two reactor system by previous batch students at NFC
IEFR. They use two reactors and didn’t use and recovery system. We are using one reactor
but installing recvovery system.

6. Procedure
The process consists of two main equilibrium reactions, with incomplete
conversion of the reactants. The first is carbamate formation: the fast
exothermic reaction of liquid ammonia with gaseous carbon dioxide (CO2) at
high temperature and pressure to form ammonium carbamate (H2N-
COONH4):
Reactor:
CO2 and liquid ammonia will be introduced in the reactor to produce
ammonium carbamate, at high temperature and pressure. The reaction is
highly exothermic, and heat from this reaction will be recovered as steam.

7. Stripper:
The mixture (ammonium carbamate & unreacted NH3 & CO2). The mixture will
be moved to stripper, where ammonium carbamate will be decomposed to
urea at high temperature and low pressure. Low pressure will cause unreacted
gases to separate from liquid urea.
 Rectifying Column:
The mixture(UREA, NH3, CO2, NH2COONH4). The mixture from stripper
will be moved to rectifying column through a expansion valve, which lower the
pressure up to 0.5MPa & in rectifying column pressure will be further reduced to
0.1MPa. This low pressure will separate gases & liquid. Gases are recycled to
reactor & liquid which is urea solution will be moved to evaporator.

9.  Cooling Tower & Scrubber:
The recycle gases from rectifying column will move to cooling tower
where they are absorbed in cool water. This hot mixture then moved to
scrubber, which will separate the gases from water at low pressure. The
purpose is to recover heat from gases & finally the gases will be moved
to reactor to produce the further urea.
 Single Effect evaporator:
Urea solution from rectifying column is 75% concenterated, is move to
single effect evaporator, where urea will be made up to 85%
concenterated.

10.  Vacuum Evaporator:
Here the ammonia solution will be concentrated up to 90%. The hot water
from both evaporator will be recovered in the form of heat energy.
 Periling Tower:
In prilling towers 90% concentrated urea is move to where hot air and water
will be provided which will make the urea granular. There will be already
present some urea granular so that urea crystals formed through seeding
process, & final product will be obtained is 99% concentrated urea.

11. Equipments
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12. Personnal
 We are four person group.
 Saad sahi, B.sc chemical engg. From University of Cambridge
United Kingdom Explore, M.sc industrial engg. From Harvard
University
 Muhammad Ali, B.sc chemical engg. From Hong Kong University
of Science and Technology M.sc metallurgy engg. From University
of California, Santa Barbara
 Ali raza, B.sc chemical engg. From Stanford University, M.sc agri
engg. From Princeton University
 Usama Butt, B.sc chemical engg. From Cambridge universty, M.sc
nuclear engg. From MIT USA

13. References
 Manures and fertilizers by A.K KOLAY
 Urea Production Technology by Mark Brouwer
 Chemical process industries