Process for the production of ammonia and purification thereof by urea synthesis

Claim 1

IN AN AMMONIA SYNTHESIS PROCESS IN WHICH NITROGEN AND HYDROGEN ARE CATALYTICALLY REACTED AT ELEVATED TEMPERATURE AND PRESSURE TO FORM AMMONIA, THE RESULTING MIXED GAS STREAM IS COOLED AT ELEVATED PRESSURE TO CONDENSE CRUDE LIQUID AMMONIA CONTAINING IMPURITIES COMPRISING HYDROGEN, NITROGEN AND ARGON, AND PURIFIED LIQUID AMMONIA PRODUCT IS RECOVERED FROM SAID CRUDE LIQUID AMMONIA AT A REDUCED PRESSURE, THE IMPROVED METHOD OF REMOVING SAID IMPURITIES WHICH COMPRISES REACTING SAID CRUDE LIQUID AMMONIA WITH CARBON DIOXIDE CONTAINING FREE OXYGEN AT ELEVATED PRESSURE, WHEREBY PORTIONS OF SAID AMMONIA AND CARBON DIOXIDE ARE COMBINED TO FORM UREA AND THE OXYGEN COMBINES WITH THE HYDROGEN IMPURITY TO FORM WATER IN A MIXED PROCESS STREAM, REMOVING EXCESS FREE AMMONIA GAS CONTAINING INERTS FROM SAID MIXED PROCESS STREAM, AND CONDENSING SAID AMMONIA GAS TO PRODUCE SAID PURIFIED LIQUID AMMONIA PRODUCT.