Method of producing carbon dioxide and ammonia from intermediate reaction products in the synthesis of urea

Claim 1

IN THE TREATMENT OF A SYNTHESIZED AQUEOUS UREA SOLUTION CONTAINING UNREACTED AMMONIA AND CARBON DIOXIDE AND INTERMEDIATE SYNTHESIS REACTION PRODUCTS, AN IMPROVED METHOD FOR DISSOCIATING SAID INTERMEDIATE REACTION PRODUCTS INTO GASEOUS AMMONIA AND CARBON DIOXIDE AND EVAPORATIVELY SEPARATING SUBSTANTIALLY ALL OF THE GAS EOUS AND UNREACTED AMMONIA AND CARBON DIOXIDE AND A PORTION OF THE WATER CONTAINED IN SAID SOLUTION WHILE. SUBSTANTIALLY SUPPRESSING THE FORMATION OF BIURET COMPRISING: PASSING SAID SYNTHESIZED UREA SOLUTION AT AN ELEVATED PRESSURE TO A DEGASSING ZONE OF DOWNWARDLY CONVERGING CONFIGURATION MAINTAINED AT A LOWER PRESSURE, TANGENTIALLY INTRODUCING SAID SOLUTION INTO THE UPPER PORTION OF SAID ZONE THEREBY IMMEDIATELY FORMING A RAPIDLY ROTATING DESCENDING AND CONVERGING VORTICAL FILM OF SAID SOLUTION, SAID SOLUTION UPON INTRODUCTION INTO SAID ZONE BEING COOLED BY EXPANSION AND PARTIAL GASIFICATION, HEATING SAID FILM OF SOLUTION ALONG ITS PATH OF DESCENT BY INDIRECT HEAT EXCHANGE TO A TEMPERATURE WHEREBY INTERMEDIATE REACTION PRODUCTS DISSOCIATE INTO GASEOUS AMMONIA AND CARBON DIOXIDE AND SUBSTANTIALLY ALL OF SAID GASEOUS AND UNREACTED AMMONIA AND CARBON DIOXIDE AND A PORTION OF THE WATER ARE EVAPORATIVELY SEPARATED FROM SAID SOLUTION, SIMULTANEOUSLY WITH SAID HEATING STEP WITHDRAWING THE THUS SEPARATED GASES FROM THE UPPER PORTION OF THE DEGASSING ZONE, AND WITHDRAWING A SUBSTANTIALLY DEGASSED CONCENTRATED UREA SOLUTION FROM THE LOWER PORTION OF SAID DEGASSING ZONE.