METHOD OF PRODUCING CARBAMIDE Russian patent published in 2012 - IPC C07C273/04 

FIELD: chemistry.

SUBSTANCE: invention relates to a method of producing carbamide from ammonia and carbon dioxide. The method is carried out at high temperature and pressure, molar ratio NH₃:CO₂=(3.4-3.7):1, in a carbamide synthesis reactor followed by extraction of excess ammonia from the carbamide synthesis fusion cake by separation at pressure 80-120 kgf/cm², two-step distillation of the fusion cake, condensation of distillation gases with formation of recycled solutions of ammonium carbonates. First-step distillation is carried out at pressure 80-120 kgf/cm² in a CO₂ current. After distillation, the fusion cake is fed to the second distillation step which is carried out at low pressure. Distillation gases from the first step are condensed in two successive zones at distillation pressure of the first step, where in the first zone, condensation is carried out while feeding a portion of ammonium carbonate solution obtained during condensation of distillation gases at the second step. The condensed vapour is cooled with a condensate which boils at excess pressure to obtain vapour. The ammonium carbonate solution from the second condensation step is fed into the reactor. At the first distillation step, CO₂ is used in amount of 30-35% of its total amount fed into the process. Gases and the liquid carbamide synthesis fusion cake are output from the carbamide synthesis reactor separately. Gases from the synthesis reactor and excess ammonia from the separation step are fed into the first condensation zone of distillation gases from the first step. In the second condensation zone of distillation gases from the first step, the condensed vapour is cooled by recycled water and uncondensed gases at the same pressure are washed by the other portion of the ammonium carbonate solution obtained during condensation of distillation gases from the second step, and the formed ammonium carbonate solution is fed into the second condensation zone.

EFFECT: process of producing carbamide with low power consumption.

1 dwg, 1 tbl, 3 ex