ENGLISH 7_Q4_LESSON 2_ Employing a Variety of Strategies for Effective Interp...
Process Simulation of Urea Plant
1. Under the guidance of
Prof. Ashish Gangwal
By
Rahul Ghalme
Chemical Engineer
2. Properties of urea
1) Molecular Weight: 60.05
2) Molecular Formula: NH2·CO·NH2
3) Melting Point: 132.7
4) Boiling Point: Decomposes
5) Fairly soluble in water
6) State : Crystal prismatic or powder
7) Flammable Limit : Non-flammable
8) Density : 1323 kg/m3 at 20-24C
3. End uses:
Urea is used in solid fertilizer, liquid fertilizer and
miscellaneous applications such as animal feed, urea,
formaldehyde resins, melamine and adhesives.
Production Pattern :
Urea is the nitrogen compound with the largest
production volume In world. Its utilization is increasing
steadily, it being the preferred nitrogen fertilizer. Because it is
the world wide shift to the high nutrient-high nitrogen
fertilizers provided by urea in solid or aq. solution form.
Urea can be easily granulated.
4.
5. Raw materials:
The principal raw materials required for this purpose
are CO2 from synthesis gas manufacture and NH3 .
Process description:
1. Ammonia and CO2 are compressed separately and
added to the high pressure autoclave which must be
water cooled due to highly exothermic nature of the
reaction. The average residence time in autoclave
which is operated on cont. basis is 1.5-2 hours. A
mixture of urea , ammonium carbamate , water and
unreacted NH3+ CO2 results.
2. The liquid effluent is let down to 27 atms and fed to a
special flash evaporator containing a gas liquid
separator and condenser .
6. Unreacted water, NH3 , CO2 as a solution are thus removed
and recycled. An aq. Solution of carbamate urea is passed to
atmospheric flash drum where further decomposition of
carbamate take place. The off-gases from this step can either
be recycled or sent to NH3 process for making chemical
fertilizer.
3.The 80% aq. Urea solution can be used as is or sent to a
vacuum evaporator to obtain urea containing less than 1%
water. The molten mass is then sprayed into a prilling tower.
7.
8.
9. a) Autoclave variables
b) Carbamate decomposition and recycle
c) Production of granular urea(Prilling)
d) Heat dissipation in autoclave
e) Corrosion
