The present invention relates- to an improved method of manufacturing urea. We have found that, the production of urea from carbon dioxide and ammonia can be effected in a simple manner by forcing the mixture of the two gases in about the pro- portions required according to the equation into a vessel capable of withstanding the pressure and maintaining the melt of ammonium salts formed, at the temperature suitable for the transformation of ammonium-carbamate into urea say from about 130 to 140 degrees centigrade introducing as much additional heat as may be found necessary. The compression and conveyance of ‘the mixed ammonia and carbon dioxide is rendered possible, according to the invention, by keeping the compressor and the pipe connections at a temperature sufficiently high to avoid the separation of liquid or solid ammonium carbamate, or carbonates. By this process the separation of ammonium carbamate in a solid, or liquid, state becomes unnecessary, and it is even possible to work continuously. In order to obtain this result, the reaction mass, after urea has been formed, is slowly discharged, while maintaining the pressure in the vessel, and the mass withdrawn is separated while lowering its pressure, into a solution of urea and a gaseous mixture of ammonia, and carbon dioxide, which mixture is again compressed and forced back into the vessel.

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1922 Bosch-Meiser BASF 1429483 Urea Process.pdf