Patent ID: 6231827
Filing Date: 2001-05-15
Classification: C01C,C07C,Y02P

Abstract:
Process for combined production of ammonia and urea in a plant comprising an ammonia synthesis reactor, a urea synthesis reactor and a urea recovery section, said process comprising the steps of:submitting at least part of a flow comprising carbamate in aqueous solution coming from said urea recovery section to a partial decomposition treatment, to obtain a flow comprising ammonia and carbon dioxide in vapour phase and a flow comprising diluted carbamate in aqueous solution;feeding said flow comprising ammonia and carbon dioxide in vapour phase to said urea synthesis reactor;feeding said flow comprising diluted carbamate in aqueous solution resulting from said treatment step, a gas flow comprising hydrogen, nitrogen and carbon dioxide, and a flow comprising ammonia coming from said ammonia synthesis reactor to a carbamate synthesis section,reacting said ammonia with said carbon dioxide in said carbamate synthesis section, to obtain a flow comprising carbamate in aqueous solution and a gas flow comprising hydrogen and nitrogen;feeding said flow comprising carbamate in aqueous solution to said urea synthesis reactor;feeding said gas flow comprising hydrogen and nitrogen to said ammonia synthesis reactor.