process simulation of urea plant in aspen plus.

1. Project Guide
Dr. S. NIGAM
BY :
13 -ADITYA DESHMUKH
16 -SANKET DIVE
22 -GAJANAN HANGE
23 -PAWAN JAMADAR

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Molecular Formula - NH2CONH2
Molecular Weight
- 60
Boiling Point
-Decomposes
Melting Point
-1320 c
Specific Gravity
-1.335
Solubility
-Fairly Soluble in Water

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Urea mostly used in solid fertilizer(53%) and
liquid fertilizer(31%) as well.
It has also found applications in animal feed,
formaldehyde resigns, and adhesives.
Urea is the nitrogen compound with the largest
production volume in the world.
Urea being preferred nitrogen fertilizer
worldwide, its utilization is increasing steadily

4. Ammonium carbamate decomposition method
Ammonia and CO2 are compressed and reacted at 100200 atms and 170-190 C in an autoclave to form
ammonium carbamate (NH4COONH2). Urea is
formed by dehydration in a low pressure stripping
operation. Process modification occur in recycle of unreacted NH3-CO2and percentage excess in reactants.

5. Although there are several processes currently used for the
manufacture of urea, the underlying principle for all the
processes is same. The two main reactions involved are:
1) CO2 + 2NH3
Kcal/gm mol
NH2COONH4
2) NH2COONH4
Kcal/gm mol
NH2CONH2 + H2O
H= -37.4
H= + 6.3
Undesirable side reaction taking place is:
3) 2NH2CONH2
NH2CONHCONH2 + NH3
(Biuret)

7. Temperature : The conversion of ammonium carbamate to urea
gradually increases as the temperature increases. However, after a
particular temperature, depending upon the pressure, the
conversion suddenly drops with further increase in temperature .
Pressure: The main reaction is sufficiently slow at atmospheric
pressure. However, it starts almost instantaneously at pressure of
the order of 100 atm and temperature of 150 oC. There is reduction
in volume in the overall reaction and so high pressure favors the
forward reaction.
Concentration: Higher the concentration of the reactants, higher
will be the forward reaction according to the law of mass action.
Residence Time: Since, urea reaction is slow and takes about 20
mins to attain equilibrium, sufficient time is to be provided to get
higher conversion