Urea synthesis

Claim 1

IN THE SYNTHESIS OF UREA WHEREIN CARBON DIOXIDE IS REACTED WITH AMMONIA IN A REACTION ZONE TO PRODUCE A PRODUCT MIXTURE CONTAINING AMMONIA, WATER, UREA AND AMMONIUM CARBAMATE AND WHEREIN THE PRODUCT MIXTURE IS TREATED TO REMOVE AMMONIUM CARBAMATE LEAVING A MIXTURE SUBSTANTIALLY FREE OF SAID CARBMATE AND CONTAINING AMMONIA, CARBON DIOXIDE, WATER AND UREA, AN IMPROVED PROCESS FOR RECOVERY OF UNREACTED AMMONIA AND CARBON DIOXIDE WHICH COMPRISES; PASSING THE LIQUID REACTION MIXTURE CONTAINING UREA, WATER, UNREACTED AMMONIA AND CARBON DIOXIDE TO A SEPARATION ZONE WHEREIN WATER AND UNREACTED AMMONIA AND CARBON DIOXIDE ARE SEPARATED AS A VAPOROUS FRACTION FROM LIQUID UREA, PASSING SAID VAPOROUS FRACTION TO A PARTIAL CONDENSATION ZONE WHEREIN WATER IS CONTINUOUSLY CONDENSED AND ISOLATED FROM THE REMAINING VAPORS DURING RESIDENCE IN SAID CONDENSATION ZONE AND MAINTAINING A LIQUID WATER PHASE SUPERIMPOSED BY A VAPOR PHASE WITHIN THE PARTIAL CONDENSATION ZONE TO PREVENT THE FORMATION OF AN EQUILIBRIUM MIXTURE, WITHDRAWING THE AMMONIA-CARBON DIOXIDE VAPORS FROM SAID CONDENSATION ZONE, AND PASSING SAID AMMONIA-CARBON DIOXIDE VAPORS TO A TOTAL CONDENSATION ZONE WHEREIN THE UNREACTED AMMONIA AND CARBON DIOXIDE ARE CONDENSED AND AN EQUILIBRIUM MIXTURE IS MAINTAINED.