Integrated ammonia-urea producing process, for the production of urea

摘要

An improvement of the SNAM ammonia-stripper integrated urea process is disclosed, wherein a gaseous stream obtained by decomposing hydrocarbons is fed to an adiabatic ammonia stripper placed downstream of a carbamate decomposer, the adiabatic stripper also receiving a solution of urea which is rich in ammonia coming from the carbamate decomposer. The thus enriched gaseous stream (NH3, CO2, H2O) is processed in a CO2-absorber (or carbamate reactor) and the process proceeds in the urea synthesis reactor. Recycling and recovery loops are provided between the several reaction and/or decomposing units. Surprisingly, enough, the stripping on NH3 and CO2 takes place adiabatically and the drop of the CO2 partial pressure in the stream fed to the carbamate reactor has no bearing on the efficiency of the carbamate conversion which, according to the current technical teachings, requires an increase of the CO2 partial pressure.