Patent ID: 7534883

Claim:
Process for the preparation of melamine which comprises a melamine preparation zone connected to a urea preparation zone through a carbamate concentration zone, wherein the process comprises: (a) generating a gas stream which is comprised of ammonia, carbon dioxide and water in a desorption column of the carbamate concentration zone, (b) generating a urea-containing stream in the urea preparation zone; (b) directing the gas stream and the urea-containing stream to a heat exchanger of the carbamate concentration zone, and (c) heat-exchanging the gas stream and the urea-containing stream in the heat exchanger of the carbamate concentration zone so that heat is exchanged between the urea-containing and the gas stream to thereby heat the urea-containing stream and to cool and at least partially condense the gas stream to obtain an ammonium carbamate solution therefrom, and (d) directing the ammonium carbamate solution from the heat exchanger to the urea preparation zone.