Treatment of ammonia synthesis purge gas

摘要

A method of synthesizing ammonia by reacting a synthesis gas comprising nitrogen and hydrogen at superatmospheric pressure in a synthesis reaction zone with recycling of unreacting gas to the reacting zone is disclosed in which a purge gas stream is withdrawn at superatmospheric pressure and subjected to the steps of: (a) work expansion, (b) separation of methane and argon to form a gaseous product stream comprising nitrogen and hydrogen, (c) recompression of at least a portion of the gaseous product stream from step (b) using work generated in step (a), and (d) recycling of at least a portion of the recompressed product from step (c) to the reaction zone. Apparatus for effecting said process is also claimed.