Method for the separation of ammonia and carbon dioxide from aqueous solutions

摘要

The present invention relates to a method for contemporaneously recovering ammonia and carbon dioxide from an aqueous solution thereof, possibly comprising their condensates, in a synthesis process of urea, characterized in that it comprises a hydrophobic microporous membrane distillation phase of an aqueous solution comprising ammonia, carbon dioxide and their saline compounds or condensates, said distillation being carried out at a temperature ranging from 50 to 250° C. and a pressure ranging from 50 KPa to 20 MPa absolute, with the formation of a residual aqueous solution, possibly comprising urea, and a gaseous permeate stream, comprising ammonia, carbon dioxide and water. The present invention also relates to an apparatus for effecting the above method and a production process of urea which comprises the above method.

主权项

1. A method for contemporaneously recovering ammonia and carbon dioxide from an aqueous solution in a urea synthesis process, the method comprising
distilling on a hydrophobic microporous membrane the aqueous solution comprising ammonia, carbon dioxide and, optionally, a saline compound or a condensate thereof, at a temperature of 50 to 250° C. and at a pressure of 50 KPa to 20 MPa absolute, to obtain a residual aqueous solution, optionally comprising urea, and a permeated gaseous stream comprising ammonia, carbon dioxide and water, wherein the aqueous solution is a recycled solution from a urea production process or an effluent coming from a urea synthesis reactor, and the aqueous solution comprises 20 to 70% by weight of ammonia, 10 to 60% by weight of carbon dioxide and 10 to 70% by weight of water.