| 摘要 |
<p>A process for the preparation of urea from ammonia and carbon dioxide at an elevated temperature and pressure having a reaction zone and a stripping zone. In the reaction zone, carbon dioxide and a portion of the ammonia are converted to ammonium carbamate, and a portion of the ammonium carbamate is converted to urea, the combined conversions resulting in a net formation of heat. In the stripping zone, a urea product stream containing unconverted ammonium carbamate is heated by heat exchange with the reaction zone to decompose a portion of ammonium carbamate. The reaction zone is maintained at a pressure of between about 125 and 250 bar, and the stripping zone is maintained at a pressure lower than the pressure in the reaction zone.</p> |
