PROCESS FOR PREPARING CARBAMIDE Russian patent published in 1997 - IPC

FIELD: technology of production of carbamide from carbon dioxide and ammonia. SUBSTANCE: carbamide is prepared by reacting ammonia with carbon dioxide in two successive synthesis zones, $$$ mole ratio being maintained at (4-5.5): 1 in first zone and (2.8-3.5):1 in second zone, and pressure is maintained at 14-23 Mpa in first zone and 14-15.5 Mpa in second zone. Fresh $$$ and $$$ and aqueous solution of carboammonium salts recirculating in the system are fed into first reaction zone. Reaction products in first zone are separated into carbamide solution and gas-liquid mixture of reagents. After addition of fresh ammonia, the mixture is directed to second synthesis zone. Melt streams from each synthesis zone are directed to first and second ammonium carbamate decomposition zones in which zones pressure is maintained which is equal to the pressure in second synthesis zone. Fresh carbon dioxide stream is fed into second decomposition zone, and outgoing gases from second decomposition zone are mixed with the meet in first decomposition zone. EFFECT: more efficient preparation process. 3 dwg, 3 tbl