PRODUCTION PROCESS FOR UREA

摘要

PROBLEM TO BE SOLVED: To provide a production process for urea that has improved heat economy. SOLUTION: Most of unreacted ammonium carbamate is subjected to the high-pressure decomposition of 1-4 MPa G in the high-pressure decomposition column G for the urea synthesis solution separated by stripping with the starting carbon dioxide with a pressure of almost same one for the urea synthesis and the separated mixture of ammonia, carbon dioxide and water is brought into contact with the condensed solution from the first condenser Q kept at almost the same pressure as that of the high-pressure decomposition pressure under the indirect heat exchange with the aqueous urea solution to be concentrated and the aqueous urea solution is heated with the condensation heat generated there. The condensed solution and the uncondensed mixture gas are introduced into the second condenser P and a part of the uncondensed gas is condensed and the rest of the uncondensed mixed gas is condensed under cooling in the first condenser, as it is brought into contact with the washing solution from the washing column kept at almost the same pressure of that of the high- pressure decomposition the still remaining mixture gas is absorbed in the washing column R.