Integrated urea-ammonia process

Abstract From the Canadian patent

This invention relates to an integrated process for the synthesis of urea and ammonia from a raw gas containing N2, H2 and CO2. This process is characterized in that the concentrated ammonium carbonate solution obtained by absorption with water of the ammonia leaving the urea synthesis zone is fed to the primary CO2 absorption zone and in that the weakly concentrated ammonical solution of ammonium carbonate obtained from the stripping zone is fed to a secondary CO2 absorption zone. Such a process enables to eliminate the use of an additional amount of water to absorb ammonia, and gives remarkable advantages as to the yield of urea and the process cost.