Chemical Industry Multiple Choice Questions on “Inorganic Chemical – Urea”.
1. What is the highest end use of urea?
a) solid fertilizer
b) liquid fertilizer
c) formaldehyde resin
Clarification: Basically, urea is used as solid fertilizer in the highest amount (53%), 31% is used as liquid fertilizer and rest are the miscellaneous application such as formaldehyde resins and melamine.
2. Which process is associated with urea production?
a) High pressure stripping operation
b) Low temperature stripping operation
c) Low pressure stripping operation
d) Low temperature stripping operation
Clarification: In ammonium carbonate process, urea is formed by dehydration in a low-pressure stripping operation. In this process ammonia and CO2 are compressed and reacted at particular operating conditions.
3. What is the undesirable product in urea production?
a) Ammonium carbonate
b) Biuret formation
c) Liquid NH3
d) Flakes formation
Clarification: In urea production, ammonium carbonate get decomposes and formed biuret which is the undesirable product increases the separation cost, flakes formed in the ammonium nitrate production.
4. In which cycle NH3 and CO2 are used as raw materials?
a) Claude cycle
b) Wulff cycle
c) Cascades cycle
d) Montecatini solution recycle
Clarification: In montecatini solution cycle, NH3 and CO2 are compressed and added to the high pressure autoclave which must be water cooled due to the highly exothermic nature of the reaction.
5. In which process NH3 is compressed and returned to the autoclave?
a) Inventa process
b) Chemico process
c) Pechiney process
d) Montecatini process
Clarification: In chemico process, CO2 is stripped from the off-gases by absorption in monoethanolamine. NH3 is recompressed and return to the autoclave and provides good temperature control.
6. What is the major engineering problem associated with ammonia production?
b) Heat recovery
c) Handling deposited carbon
d) Burner design
Clarification: This has been the major reason why NH3CO2 process was slow to develop. High cost silver or tantalum liners are used in the autoclave with hastelloy C, titanium, stainless steel and aluminium alloys used in order to reduce corrosion.
7. Which prevention can be taken to avoid the formation of biuret?
a) Temperature > melting point
b) Temperature < melting point
c) Temperature > boiling point
d) Temperature < boiling point
Clarification: In urea production to avoid formation of biuret in percentage > 1%, the temperature must be kept just above the melting point for processing time of 1-2 seconds in this phase of operation.
8. In which process unconverted NH3 is absorbed?
a) Stamicarbon process
b) Toyo koatsu process
c) Inventa process
d) Hot- recycle process
Clarification: In inventa process, unconverted NH3 is absorbed in aqueous urea nitrate solution, then stripped and returned to autoclave. It provides better temperature control. Recycle gases are absorbed in stamicarbon process.
9. Which raw material used for the production of urea?
Clarification: The principal raw materials required for the production of urea are CO2 from synthesis gas manufacture and NH3 in an amount of 1.15 ton and 1.47 ton respectively for once- through process.