Back to results
US 12,319,662 B2Granted
Coupled urea melamine plant
AssigneeStamicarbon B.V.
InventorRahul Patil
Life of this patent
Estimating the term…
Abstract
The disclosure pertains to a plant and process for the coupled production of urea and melamine. In an embodiment, a lean carbamate solution is supplied from the melamine production section to a recovery section of the urea production section. In an embodiment, enriched carbamate solution from the urea production section is supplied to an off-gas condenser of the melamine production section.
Claims18
A process for the coupled production of urea and melamine, comprising:
- producing urea in a urea synthesis section of a urea production section giving a first urea stream;
- subjecting said first urea stream to purification in at least a low pressure recovery section;
- producing melamine in a high pressure non-catalytic melamine synthesis section, giving molten melamine and anhydrous off-gas, said melamine synthesis section comprised in a melamine production section;
- washing the anhydrous off-gas by contact with urea in a washing unit and subjecting the washed off-gas to condensation in an off-gas condenser in the melamine production section at a pressure of at least 25 bar to form off-gas condensate;
- in a melamine processing section, dissolving the molten melamine in an aqueous solution and crystallizing the melamine with the formation of a stream of crystallized melamine and a stream of mother liquor, and treating a part or all of the mother liquor yielding recovered mother liquor and an aqueous carbamate solution;
- supplying a part or all of said aqueous carbamate solution to a carbamate condenser comprised in said low pressure recovery section, thereby forming enriched carbamate solution
- supplying at least a part of said enriched carbamate solution directly or indirectly to the off-gas condenser.
4 more elements
A plant for the coupled production of urea and melamine, comprising:
- a urea production section comprising
- a urea synthesis section for producing urea giving a first urea stream;
- a low pressure recovery section for purifying said first urea stream;
- and
- a melamine production section comprising:
- a high pressure non-catalytic melamine synthesis section for producing melamine, giving molten melamine and anhydrous off-gas;
- a washing unit for washing the anhydrous off-gas by contact with urea;
- an off-gas condenser for condensing the off-gas at a pressure of at least 25 bar to form off-gas condensate;
- a melamine processing section comprising a unit for dissolving the molten melamine in an aqueous solution, and a crystallizer for crystallizing the melamine with the formation of a stream of crystallized melamine and a stream of mother liquor;
- and
- a treatment unit for treating a part or all of the mother liquor yielding recovered mother liquor and an aqueous carbamate solution,
- wherein the plant comprises a liquid flow line for supplying a part or all of said aqueous carbamate solution to a carbamate condenser comprised in said low pressure recovery section which has an outlet for enriched carbamate solution, and a liquid flow line for supplying at least a part of said enriched carbamate solution directly or indirectly to said off-gas condenser.
9 more elements
A method of modifying an existing plant for the coupled production of urea and melamine, the existing plant comprising:
- a urea production section comprising
- a urea synthesis section for producing urea giving a first urea stream;
- a low pressure recovery section for purifying said first urea stream, comprising a carbamate condenser with an outlet for enriched carbamate solution;
- a melamine production section comprising:
- a high pressure non-catalytic melamine synthesis section of the high pressure non catalytic type for producing melamine, giving molten melamine and anhydrous off-gas;
- a washing unit for washing the anhydrous off-gas by contact with urea
- an off-gas condenser for condensing the off-gas at a pressure of at least 25 bar to form off-gas condensate;
- a melamine processing section comprising a unit for dissolving the molten melamine in an aqueous solution, and a crystallizer for crystallizing the melamine with the formation of a stream of crystallized melamine and a stream of mother liquor, and
- a treatment unit for treating a part or all of the mother liquor yielding recovered mother liquor and an aqueous carbamate solution,
- and a liquid flow line from an outlet of off-gas condenser for said off-gas condensate to an inlet of said urea synthesis section;
- the method comprising:
- providing the plant with a flow line from an outlet of said treatment unit for said aqueous carbamate solution to said carbamate condenser comprised in said low pressure recovery section;
- and preferably providing a liquid flow line from an outlet for said enriched carbamate solution directly or indirectly to said off-gas condenser.
10 more elements
A process for the coupled production of urea and melamine, comprising:
- producing urea in a urea synthesis section of a urea production section giving a first urea stream;
- subjecting said first urea stream to purification in at least a low pressure (LP) recovery section;
- producing melamine in a high pressure non-catalytic melamine synthesis section, giving molten melamine and anhydrous off-gas, said melamine synthesis section comprised in a melamine production section;
- washing the anhydrous off-gas by contact with urea in a washing unit and subjecting the washed off-gas to condensation in an off-gas condenser in the melamine production section at a pressure of at least 25 bar to form off-gas condensate, and in a melamine processing section, dissolving the molten melamine in an aqueous solution and crystallizing the melamine with the formation of a stream of crystallized melamine and a stream of mother liquor, and treating a part or all of the mother liquor yielding recovered mother liquor and an aqueous carbamate solution;
- wherein the process further comprises:
- supplying a carbamate solution from an LP carbamate condenser comprised in the LP recovery section to the off-gas condenser, wherein the LP carbamate condenser receives a gas stream from the purification step in the LP recovery section.
3 more elements
Dependencies are inferred from the claim text.