Melamine recovery

Claim 1

IN A PROCESS FOR RECOVERING MELAMINE FROM A HOT MELAMINE CONTAINING GASEOUS MIXTURE WHICH IN ADDITION TO MELAMINE CONTAINS MAINLY AMMONIA AND CARBON DIOXIDE, IN WHICH PROCESS THE GASEOUS MIXTURE IS COOLED BY DIRECT CONTACT WITH WATER IN A COOLING ZONE AND THE MELAMINE SEPARATES FROM THE GASEOUS MIXTURE AND IS DISCHARGED FROM THE COOLING ZONE, THE IMPROVEMENT COMPRISING THE STEPS OF: USING AS THE GASEOUS MIXTURE ONE CONSISTING ESSENTIALLY OF MELAMINE, AMMONIA AND CARBON DIOXIDE; FIRST COOLING THE HOT GASEOUS MIXTURE BY PASSING THE GASEOUS MIXTURE INTO A FIRST COOLING ZONE, THE INNER SURFACE OF WHICH IS COOLED IN CONCURRENT RELATION TO THE GASEOUS MIXTURE WITH A COOLANT CONSISTING ESSENTIALLY OF COOLING WATER WHICH IS SUBSTANTIALLY SATURATED WITH AMMONIA AND CARBON DIOXIDE WHEREBY SAID GASEOUS MIXTURE IS COOLED BY THE EVAPORATION OF WATER FROM THE COOLANT AND A LARGE PORTION OF THE MELAMINE IS CONDENSED AND SEPARATES FOM THE GASEOUS MIXTURE; THEN PASSING THE COOLANT INTO A SECOND COOLING ZONE AND PASSING THE PROCOOLED GASEOUS MIXTURE THROUGH THE SECOND COOLING ZONE IN COUNTERCURRENT RELATION TO THE COOLANT WHILE DIRECTLY CONTACTING THE PRECOOLED GASEOUS MIXTURE WITH THE COOLANT, COOLING OF THE GASEOUS MIXTURE BEING EFFECTED BY CONTACT WITH A VIRTUALLY CONSTANT AMOUNT OF WATER, PREDOMINANTLY BY EVAPORATION OF THIS WATER, WHEREBY THE CONDENSATION AND SEPARATION OF MELAMINE FROM THE GASEOUS MIXTURE IS COMPLETED; DISCHARGING THE SEPARATED MELAMINE FROM THE FIRST COOLING ZONE AND SEPARATELY DISCHARGING THE REMAINDER OF THE GASEOUS MIXTURE INCLUDING EVAPORATED WATER; AND SUPPLYING ADDITIONAL COOLING WATER TO THE COOLANT IN AN AMOUNT EQUIVALENT TO THE AMOUNT OF WATER REMOVED FROM THE COOLANT BY THE EVAPORATION OF WATER AND ENTRAINMENT WITH THE MELAMINE AND GASEOUS MIXTURE DISCHARGED FROM THE COOLING ZONES WHEREBY THE AMOUNT OF COOLING WATER IN THE COOLANT IS MAINTAINED SUBSTANTIALLY CONSTANT AND THE GASEOUS MIXTURE DISCHARGED FROM THE COOLING ZNES CONTAINS AT LEAST 90% OF THE AMOUNT OF THE AMMONIA ORIGINALLY PRESENT IN THE GASEOUS MIXTURE FED TO THE COOLING ZONES.