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[keby82lly]

hi all,

i am currently doing my final year project about urea plant and i am assigned to design a high pressure scrubber. I am confuse about the use of the scrubber.

For your information, my top product of urea reactor (NH3,CO2,H2O and inert gas)is fed to a carbamete condenser before sent to a scrubber. In carbamate condenser, NH3 and CO2 is condensed and converted to ammonium carbamate in liquid phase and recycled back to the system, while inert gas and uncondense gas is released in gas phase. If all the CO2 and NH3 can be converted to ammonium carbamate and recycle back to system, may i know what is the purpose of scrubber? If not, may i know the conversion of CO2 to ammonium carbamate in carbamate condenser?

From literature review, I found out that the heat of reaction of 2NH3(g)+CO2(g)->ammonium carbamate(l) is -130kJ/mol at 25C, 1atm. I can't find any heat capacity, Cp value for ammonium carbamate. May i know what is the heat of reaction at 140bar, 190C?

Thanks & best regards,
lim

[kkala]

.. top product of urea reactor (NH3,CO2,H2O and inert gas)is fed to a carbamete condenser before sent to a scrubber. In carbamate condenser, NH3 and CO2 is condensed and converted to ammonium carbamate in liquid phase and recycled back to the system, while inert gas and uncondense gas is released in gas phase. If all the CO2 and NH3 can be converted to ammonium carbamate and recycle back to system, may i know what is the purpose of scrubber?

I can only answer to this question, even though you have other questions following. Evidently there is some quantities of NH3, CO2, even carbamate, escaping into gas. This is usual in industrial reactions, even if the reactants are in stoichiometric proportion. NH3 and carbamate has to be kept through the mentioned scrubber to eliminate (or just to limit to acceptable values) emission of these pollutants to atmosphere.
But why use a high pressure drop scrubber? Probable because fine particles are formed, needing such a scrabber to be "arrested". I had a similar experience, in the gas treatment after NH3+H3PO4 neutralization, where aerosols were formed, attributed to particles of NH4Cl. Search litterature for your case.