PROCESS FOR UREA PRODUCTION, RELATED PLANT AND REVAMPING METHOD OF A PRE-EXISTING PLANT

摘要

A process for urea production from ammonia and carbon dioxide, in which part of the aqueous solution comprising urea, ammonium carbamate and ammonia obtained in a urea synthesis section is subjected to dissociation in a treatment section operating at a predetermined medium pressure for the recovery of the ammonium carbamate and of the ammonia contained in it, comprises the steps of subjecting the urea aqueous solution resulting from the aforementioned dissociation step to decomposition in a low pressure urea recovery section and of using at least a part of the condensed steam, obtained by indirect thermal exchange with a second part of said aqueous solution comprising urea, ammonium carbmate and ammonia in a high- pressure stripping unit, as a heating fluid for the dissociation of the first part of the aqueous solution comprising urea, ammonium carbmate and ammonia in the medium-pressure treatment section.