Process for preparing urea
AssigneeDsm N.V.
InventorsJulius G. T. Van Wijck, Jozef H Meessen
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Abstract
Process for the preparation of urea, in which the gas stream which is released during the synthesis of melamine and is composed essentially of ammonia and carbon dioxide is used to synthesize urea, in which process the gas stream which originates from a high-pressure melamine process and is composed essentially of ammonia and carbon dioxide is condensed at a pressure virtually equal to the pressure in the melamine reactor, in which process substantially anhydrous ammonium carbamate is formed, after which said ammonium carbamate is fed to a high-pressure section of a urea stripping plant.
Claims17
Process for the preparation of urea, in which the gas stream which is released during the synthesis of melamine and is essentially composed of ammonia and carbon dioxide is used to synthesize urea, characterized in that the gas stream which originates from a high-pressure melamine process and is essentially composed of ammonia and carbon dioxide is condensed at a pressure virtually equal to the pressure in the melamine reactor, in which process substantially anhydrous ammonium carbamate is formed, after which said ammonium carbamate is fed to a high-pressure section of a urea stripping plant.
A process for preparing urea in an integrated melamine synthesis-urea synthesis installation, the melamine synthesis being achieved in a high pressure melamine synthesis process and the urea synthesis being achieved in a urea stripping plant, with the urea stripping plant including a high pressure section, said high pressure section including a urea reactor, a carbamate condenser, a urea stripper, and interconnecting lines, comprising, in numerical order, the steps of:
- (1) obtaining a gas stream from a high pressure melamine synthesis process, the high pressure melamine synthesis process comprising reacting an urea melt in a melamine reactor to produce melamine, carbon dioxide, and ammonia, with the melamine reactor having a first operating pressure of at least 5 MPa and a first operating temperature of at least 300.degree. C., the gas stream consisting essentially of ammonia and carbon dioxide and having a pressure substantially equal to the pressure in the melamine reactor;
- (2) condensing the gas stream to form a liquid substantially anhydrous ammonium carbamate stream;
- (3) feeding the liquid substantially anhydrous ammonium carbamate stream directly to the high pressure section of the urea stripping plant;
- and
- (4) reacting at least the liquid substantially anhydrous ammonium carbamate stream in the urea stripping plant to produce urea.
Dependencies are inferred from the claim text.