SYNTHESIS PROCESS OF UREA

摘要

Urea is prepd. from CO2 and NH2. The process comprises a) reacting CO2 with excess NH3 at urea synthesis pressure and temp. to obtain a crude urea synthesis melt(A), b) separating unreacted CO2 and NH3 from (A) to convert (A) into an aq. urea soln., c) absorbing at least part of the unreacted CO2 and NH3 which can be sepd. with an absorbent, and d) recycling the absorbent to the urea synthesis reactor. In the prepn. of urea, samples of the reaction mixt. are regularly withdrawn and analyzed for NH3 and H2NCOONH2 content, and the reaction contents are adjusted accordingly.