| 摘要 |
In a process for producing urea from nitrogen and a gas mixture comprising carbon dioxide and hydrogen wherein the gas mixture is compressed and cooled to liquify the carbon dioxide and separate it from the hydrogen, ammonia is synthesised from the nitrogen and the separated hydrogen, and the ammonia produced is reacted directly with the carbon dioxide, the operating conditions are selected so that no external source of heat or pressure is applied between the synthesis of the ammonia and the reaction of the ammonia with the carbon dioxide. A mixture of carbon dioxide and hydrogen obtained by the <PICT:0974412/C1/1> partial combustion of fuel oil is compressed to 300 atmospheres by a compressor 1, passed through a heat exchanger 2, cooled to -50 DEG C. in a cooler 3 and liquid carbon dioxide is collected in a vessel 5. The hydrogen is passed through a plant 6 to remove remaining carbon dioxide and any carbon monoxide, mixed with nitrogen at 7 and the mixture reacted in a plant 8 to obtain liquid ammonia in a vessel 9. Liquid carbon dioxide and liquid ammonia from vessels 5 and 9 pass through a heat exchanger 10 to an autoclave 11 under a pressure of 270 atmospheres where urea is obtained together with water, ammonia, carbon dioxide and ammonium carbamate. Subsequently the urea is separated and granulated as described in Specification 974,411. |
