PROCESS FOR SEPARATING AND RECOVERING UNREACTED MATERIALS IN UREA SYNTHESIS

摘要

A urea synthesis effluent is subjected to at least one high pressure decomposition stage and then a low pressure decomposition stage to decompose and recover unreacted materials contained in said effluent for recycle to the urea synthesis. The urea synthesis effluent discharged from a high pressure decomposition stage is cooled to 105.degree. - 170.degree.C. by indirect heat exchange with the urea synthesis effluent in the rectification zone of the low pressure decomposition stage, and then is flashed into the top of said rectification zone, whereby the bottom of said rectification zone is heated to 100.degree. 140.degree.C and the temperature at the top of said rectification zone is maintained at 60.degree. - 120.degree.C to minimize the water content in the distillate from the rectification zone.