METHOD FOR MODERNIZING A UREA PRODUCTION PLANT, PROCESS AND PLANT FOR UREA PRODUCTION

摘要

A method for the modernization of a plant for urea production comprising a reactor (2) for urea synthesis, a stripping unit (3) with carbon dioxide and at least one vertical condensation unit (4) of the film type, includes the step of providing in the condensation unit (4) means for subjecting to substantially total condensation a portion of a flow comprising ammonia and carbon dioxide in vapour phase leaving said stripping unit (3), and is characterized in that it further comprises the steps of providing a second stripping unit (47), means (9) for feeding a first portion of the flow of reaction mixture comprising urea, carbamate and free ammonia in aqueous solution leaving the reactor (2) to said stripping unit (3), means (48) for feeding a second portion of the flow of reaction mixture comprising urea, carbamate and free ammonia in aqueous solution leaving the reactor (2); to said second stripping unit (47) and means (49) for feeding at least a portion of a flow comprising ammonia and carbon dioxide in vapour phase leaving said second stripping unit (47) directly to the reactor synthesis (2).