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US 12,139,448 B2Granted
Urea and melamine production
AssigneeStamicarbon B.V.
InventorsSolomon Assefa Wassie, Rahul Patil
Life of this patent
Estimating the term…
Abstract
The disclosure pertains to urea production with, in series, an MP carbamate condenser for condensing at least urea synthesis section off-gas, gas/liquid separation giving a gas stream and a liquid stream, and a second carbamate condenser receiving off-gas from melamine production and said liquid stream.
Claims19
An integrated urea and melamine production process comprising:
- producing urea in a high pressure (HP) urea synthesis section of the stripping type, giving a stripped urea solution also comprising carbamate, and a separate urea synthesis section off-gas stream comprising inert gases, NH3 and CO2;
- producing melamine thereby making available a melamine off-gas stream;
- subjecting the stripped urea solution to medium pressure (MP) treatment wherein at least some of the carbamate contained in the stripped urea solution is dissociated into CO2 and NH3, giving an MP urea solution and a first MP gas stream;
- subjecting at least a part of the urea synthesis section off-gas stream and the first MP gas stream to condensation in a first medium pressure (MP) carbamate condenser to give an MP condenser effluent;
- subjecting the MP condenser effluent to gas/liquid separation to give a second MP gas stream comprising said inert gases, and a first MP carbamate solution;
- subjecting the melamine off-gas stream to condensation in a second MP carbamate condenser in the presence of at least a part of the first MP carbamate solution, to give a second MP carbamate solution;
- and
- supplying the second MP carbamate solution directly or indirectly to the urea synthesis section.
5 more elements
An integrated urea and melamine production plant comprising:
- a high pressure (HP) urea synthesis section of the stripping type, having an outlet for a stripped urea solution also comprising carbamate, and a separate outlet for a urea synthesis section off-gas stream comprising inerts, NH3 and CO2;
- a melamine production section having an outlet for a melamine off-gas stream;
- an MP treatment unit for treating the urea solution at medium pressure, wherein at least some of the carbamate contained in the stripped urea solution is dissociated into CO2 and NH3, having an outlet for an MP urea solution and an outlet for a first MP gas stream;
- a first MP carbamate condenser for subjecting at least a part of the urea synthesis section off-gas stream and the first MP gas stream to condensation to give an MP condenser effluent;
- a gas/liquid separation zone for subjecting the MP condenser effluent to gas/liquid separation to give a second MP gas stream and a separate first MP carbamate solution;
- a second MP carbamate condenser for subjecting the melamine off-gas stream to condensation in the presence of at least a part of the first MP carbamate solution, to give a second MP carbamate solution;
- and
- a liquid flow line for supplying the second MP carbamate solution directly or indirectly to the urea synthesis section.
5 more elements
A method of modifying an existing urea plant, the existing urea plant comprising:
- a high pressure (HP) urea synthesis section of the stripping type, having an outlet for a stripped urea solution also comprising carbamate, and a separate outlet for a urea synthesis section off-gas stream comprising inerts, NH3 and CO2;
- wherein the method involves:
- adding, if not already present in the existing urea plant:
- a melamine production section having an outlet for a melamine off-gas stream;
- an MP treatment unit for treating the urea solution at medium pressure, wherein at least some of the carbamate contained in the urea solution is dissociated into CO2 and NH3, having an outlet for an MP urea solution and an outlet for a first MP gas stream;
- a first MP carbamate condenser for subjecting at least a part of the urea synthesis section off-gas stream and the first MP gas stream to condensation to give an MP condenser effluent;
- a gas/liquid separation zone for subjecting the MP condenser effluent to gas/liquid separation to give a second MP gas stream and a first MP carbamate solution;
- and wherein the method comprises adding:
- a second MP carbamate condenser for subjecting the melamine off-gas stream to condensation in the presence of at least a part of the first MP carbamate solution, to give a second MP carbamate solution;
- and
- a liquid flow line for supplying the second MP carbamate solution directly or indirectly to the urea synthesis section.
8 more elements
Dependencies are inferred from the claim text.