Synthesizing urea

Claim 1

IN THE METHOD OF PRODUCING UREA BY THE REACTION OF CO2 WITH NH3 TO FORM AN EFFLUENT CONTAINING UREA, WATER, UNREACTED CO2 AND UNREACTED NH3, THAT IMPROVEMENT IN SEPARATING UNREACTED CO2 AND NH3 FROM SAID EFFLUENT FOR REUSE IN PRODUCING UREA COMPRISING, SUBJECTING SAID EFFLUENT TO A FIRST DISTILLATION AT A GAUGE PRESSURE OF ABOUT 10 TO ABOUT 25 KG./CM.2, A HEAD TEMPERATURE OF ABOUT 90*C. TO ABOUT 130*C. AND A STILL TEMPERATURE OF ABOUT 130*C. TO ABOUT 170*C. TO DRIVE OFF NH3 AND CO2 WHILE MINIMIZING THE DISTILLATION OF WATER AND LEAVING A DEPLETED LIQUID; SUBJECTING SAID DEPLETED LIQUID TO A SECOND DISTILLATION AT A GAUGE PRESSURE OF ABOUT 0 TO ABOUT 3 KG./CM.2, A HEAD TEMPERATURE OF ABOUT 60*C. TO ABOUT 140*C. TO DRIVE OFF THE REMAINING CO2 AND NH3 WHILE MAINIMIZING THE DISTILLATION OF WATER AND LEAVING AN AQUEOUS SOLUTION CONTAINING UREA; REMOVING FROM SAID SOLUTION AN AMOUNT OF WATER APPROXIMATEELY CORRESPONDING TO THAT AMOUNT FORMED IN SAID REACTION AND SEPARATING SOME UREA FROM SAID SOLUTION TO LEAVE AN AQUEOUS UREA-CONTAINING MOTHER LIQUOR; AND ABSORBING THE CO2 AND NH3 FROM SAID FIRST AND SECOND DISTILLATIONS IN SAID LIQUOR FOR REUSE IN THE PRODUCTION OF UREA.