Patent ID: 6342632
Filing Date: 2002-01-29
Classification: C07C,Y02P

Abstract:
A process for urea production, comprising the steps of:reacting ammonia and carbon dioxide in a reaction space to obtain a reaction mixture comprising urea, carbamate and free ammonia in aqueous solution; subjecting said mixture to a treatment of partial decomposition of the carbamate and partial separation of said free ammonia in aqueous solution to obtain a first flow comprising ammonia and carbon dioxide in vapor phase and a flow comprising urea and residual carbamate in aqueous solution; subjecting said first flow comprising ammonia and carbon dioxide in vapor phase to at least partial condensation to obtain a first portion of carbamate in aqueous solution; recycling said first portion of carbamate to said reaction space; feeding said flow comprising urea and residual carbamate in aqueous solution to a urea recovery section; separating in said recovery section said residual carbamate from the urea to obtain a second portion of carbamate in aqueous solution; subjecting at least part of said second portion of carbamate in aqueous solution obtained in said recovery section to a treatment of partial decomposition to obtain a second flow comprising ammonia and carbon dioxide in vapor phase and a flow comprising residual carbamate in aqueous solution; subjecting said second flow comprising ammonia and carbon dioxide in vapor phase to at least partial condensation to obtain a third portion of carbamate in aqueous solution; and recycling said third portion of carbamate to said reaction space.