METHOD OF PRODUCING UREA Russian patent published in 1996 - IPC

FIELD: chemical engineering; urea production. SUBSTANCE: urea is produced by interaction of carbon dioxide with excess ammonia in two separated synthesis zones with feeding of recycled reactants only into the 1st zone wherein lower pressure than that in the 2nd zone is maintained. Out of melt from the 2nd zone, gases are released at the same pressure as that in the 1st zone. Released gases are conveyed into the step of absorption- condensation of reactants distilled out of synthesis melt at pressure equal to that in the 1st zone. Separation of gas products out of melt coming from the 2nd zone is preferable to be carried out with gas flow from the 2nd zone or gases from stripping zone. Stripped urea solution is successively treated in the steps of low- pressure distillation and water vacuum-distillation to yield concentrated urea and aqueous solution of carbon-ammonium salts recycled as absorbent. EFFECT: reduced power consumption. 4 cl, 4 dwg