Method for controlling the ammonia and CO.sub.2 ratios in a urea manufacturing process

摘要

A process for urea manufacture is described wherein the molar ratio of unreacted NH.sub.3 to CO.sub.2 (including NH.sub.3 and CO.sub.2 in the form of ammonium carbamate) in the carbamate reaction liquid phase is between 2:1 and 3:1, and the same ratio in the liquid phase in the urea autoclave is maintained between 3:1 and 6:1, control of the process being achieved by analysis of the gas phase and maintaining the NH.sub.3 to CO. sub. 2 molar ratio therein between about 1:1 and 6:1, preferably between about 1.5:1 and 3.5:1, in both the carbamate reactor and the urea autoclave.