METHOD AND INSTALLATION FOR PRODUCING UREA Russian patent published in 2024 - IPC C07C273/04 

FIELD: industrial chemistry.

SUBSTANCE: method for producing urea from ammonia and carbon dioxide. The method includes the interaction of ammonia and carbon dioxide in the synthesis zone at elevated temperatures and pressures with the formation of a urea melt stream, distillation of a urea melt stream with the addition of heat sequentially at a high pressure stage at 14.0-16.5 MPa, at a medium pressure stage at 1. 5-2.5 MPa and low pressure stages at 0.2-0.5 MPa, with the formation of an aqueous solution of urea and distillation gases, condensation-absorption when cooling distillation gases using aqueous absorbents and the formation of aqueous solutions of ammonium carbon salts (ACS), recirculation of the aqueous ACS solution sequentially from the condensation-absorption stage of distillation gases of the low-pressure stage to the condensation-absorption stage of medium-pressure distillation gases, then to the condensation-absorption stage of distillation gases of the high-pressure stage, and then to the synthesis zone, evaporation of the aqueous solution of urea in several stages. In this case, the distillation of urea melt at the high-pressure stage is carried out sequentially in two zones, in the first of which adiabatic throttling of the urea melt is carried out to a pressure at least 0.01-0.4 MPa lower than the synthesis pressure, and adiabatic separation is carried out, and in the second, distillation is carried out by supplying heat from an external source in a stream of carbon dioxide. An installation for implementing the method is also proposed.

EFFECT: increasing the specific productivity of the urea synthesis reactor, reducing the gas and heat load on the stripper-distiller, and reducing the cost of the stripper-distiller.

12 cl, 1 dwg, 4 ex