Patent ID: 7608735
Filing Date: 2009-10-27
Classification: C07C

Abstract:
1. Process for urea production from ammonia and carbon dioxide, comprising the steps of: feeding ammonia and carbon dioxide into a urea synthesis section operating at a predetermined high pressure; making said ammonia and said carbon dioxide react in said synthesis section obtaining an aqueous solution comprising urea, ammonium carbamate and ammonia; feeding a part of said aqueous solution comprising urea, ammonium carbamate and ammonia to a treatment section operating at a predetermined medium pressure for the recovery of the ammonium carbamate and of the ammonia contained in it; subjecting said part of aqueous solution comprising urea, ammonium carbamate and ammonia to dissociation in said treatment section obtaining an urea aqueous solution and a vapour phase comprising ammonia, carbon dioxide and water; subjecting said vapour phase comprising ammonia, carbon dioxide and water to condensation in said treatment section obtaining an ammonium carbamate aqueous solution; recycling said ammonium carbamate aqueous solution to said urea synthesis section; characterized in that it comprises the further steps of: feeding said urea aqueous solution obtained by dissociation in said treatment section to a decomposer of a urea recovery section operating at a predetermined low pressure; subjecting said urea aqueous solution to decomposition in said decomposer of said urea recovery section obtaining a concentrated urea solution and a second vapour phase comprising ammonia, carbon dioxide and water; subjecting said second vapour phase to condensation in a condenser of said urea recovery section in fluid communication with said decomposer obtaining a recycle ammonium carbamate aqueous solution.