Treatment of ammonia synthesis purge gas

Abstract From the Canadian patent

In the synthesis of ammonia with recycle of unreacted nitrogen and hydrogen to the reactor, a purge gas stream is removed from the recycle stream and partially condensed using refrigeration provided by the expansion and subsequent vaporization of the condensate the, gaseous stream from the partial condensation is returned to the reactor and a bleed stream is removed from this gaseous stream and expanded and injected into the expanded condensate. Accumulation of helium, argon and methane impurities in the reactor can thus be prevented and the expanded vaporized combined condensate and bleed can be recovered at a suitable pressure for use as a fuel gas stream.