Power recovery in ammonia synthesis

Claim 1

IN AN AMMONIA SYNTHESIS PROCESS IN WHICH A SYNTHESIS GAS MIXTURE OF NITROGEN AND HYDROGEN IS PASSED THROUGH A CATALYTIC CONVERTER AT ELEVATED PRESSURE AND TEMPERATURE, WHEREBY A PORTION OF THE GAS MIXTURE IS CONVERTED TO AMMONIA, THE RESULTING HOT GAS MIXTURE IS COOLED TO CONDENSE LIQUID AMMONIA, THE LIQUID AMMONIA PRODUCT IS SEPARATED FROM THE RESIDUAL SYNTHESIS GAS MIXTURE, AND THE RESIDUAL SYNTHESIS GAS MIXTURE TOGETHER WITH MAKEUP GAS MIXTURE IS RECYCLED FOR FURTHER CATALYTIC AMMONIA SYNTHESIS, THE IMPROVED METHOD OF RECOVERING HEAT FROM THE HOT GAS MIXTURE AS USABLE POWER WHICH COMPRISES COOLING THE HOT GAS MIXTURE BY HEAT EXCHANGE WITH A VOLATILE ORGANIC LIQUID AT ELEVATED PRESSURE, WHEREBY SAID ORGANIC LIQUID IS HEATED AND VAPORIZED, EXPANDING THE RESULTING ORGANIC VAPOR THROUGH MECHANICAL POWER RECOVERY MEANS TO A REDUCED PRESSURE, COOLING THE ORGANIC VAPOR TO CONDENSE SAID VAPOR TO THE LIQUID STATE, PUMPING THE RESULTING ORGANIC LIQUID TO ELEVATED PRESSURE, AND RECYCLING THE ORGANIC LIQUID FOR FURTHER HEAT EXCHANGE WITH THE HOT GAS MIXTURE.