Patent ID: 6287525
Filing Date: 2001-09-11
Classification: C07C,Y02P

Abstract:
A method for modernizing a plant for urea production of the type comprising:a urea synthesis reactor (R-1);a stripping equipment (4) for subjecting a first reaction mixture leaving said reactor (R-1) to a treatment of partial decomposition of the carbamate and partial separation of the free ammonia in aqueous solution present in said first mixture;means (5) for condensing at least partially the vapors leaving said stripping equipment (4) and recycling a first carbamate solution to said reactor (R-1);a recovery section (3) for separating the urea produced in said reactor (R-1) from a second aqueous carbamate solution;characterized in that it comprises the steps of:providing a second urea synthesis reactor (R-2) upstream of said stripping equipment (4);connecting said second reactor (R-2) with said stripping equipment (4);providing means (9, 25, 26) for recycling to said second reactor (R-2) the second carbamate solution obtained in the recovery section (3); andproviding a duct (33) for recycling to said second reactor (R-2) the vapors leaving the top of said first reactor (R-1).