PROCESS OF PRODUCING GAS FOR SYNTHETIC AMMONIA

Ammonia synthesis gas comprising hydrogen and nitrogen is produced by starting from a gas mixture which is high in particular in hydrogen and carbon monoxide and contains methane as impurity. The gas mixture is converted catalytically (2) and the CO2 is removed (5) from the converted gas mixture which has a CO content of about 2 to 8 % by volume. The gas mixture is precooled to maximum temperatures of -50 DEG C (8) and cooled further in a heat-exchange zone to maximum temperatures of -160 DEG C. In the heat-exchange zone (11), the temperature of the high-hydrogen gas mixture drops below the dew point of methane, thus making it possible to separate off a condensate which is high in methane (13). In a washing stage (20) using liquid nitrogen, carbon monoxide is removed from the gas mixture as a condensate. In the heat-exchange zone (11), at least a portion of the condensate which is high in CO is evaporated and passed to the converting stage (30). A gas mixture containing H2 and N2 (24) is removed from the liquid nitrogen washing stage and also passed through the heat-exchange zone.