Abstract: In a process for the recovery of hydrogen from compressed purge gas withdrawn from a recyling gas stream of an ammonia synthesis wherein the hydrogen is separated from the purge gas by partial condensation at cryogenic temperatures, refrigeration is provided by expanding and evaporating the condensate so formed, and the partial pressure of the expanded condensate is lowered by withdrawing a bleed stream from said uncondensed gas, expanding said bleed stream and injecting it into said expanded condensate, condensation of nitrogen employed to purge the cold box for the cryogenic process is avoided by either injecting into the bleed stream a warmer gas provided from the uncondensed gas and/or the purge gas or expanding the condensate and bleed stream in stages with separate expansion thereof in an initial stage and injection of the bleed stream into the condensate prior to the final stage.

Abstract: Argon is recovered from a tail gas stream remaining after recovery of hydrogen values from ammonia synthesis purge gas. In a first step, tail gas is cooled, preferably in a first heat exchanger then a refluxing exchanger, to separate a condensate containing methane, argon and some nitrogen and uncondensed gas containing substantially all residual hydrogen and some nitrogen. The condensate, after expansion, is fed into a first distillation column where methane is condensed, the overhead nitrogen and argon product being fed to a second column where argon product is condensed. The cold requirements of the process and heat for reboil and cooling for reflux for the columns are provided by an open cycle supplied with gaseous nitrogen from the second column as heat transfer fluid. Cooling for the refluxing exchanger is provided by an evaporating coolant comprising transfer fluid combined with the uncondensed nitrogen-hydrogen gas after expansion thereof.

Abstract: 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reaction zone with recycling of unreacting gas to the reacting zone is disclosed in which a purge gas stream is withdrawn at superatmospheric pressure and subjected to the steps of: (a) work expansion, (b) separation of methane and argon to form a gaseous product stream comprising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.

Abstract: Ammonia and hydrogen values are recovered from the purge gas from an ammonia synthesis recycle stream by removing the ammonia from the purge gas by adsorption in an ammonia adsorber, thereafter separating the hydrogen by cryogenic partial condensation, the refrigeration for which is provided by expanding and evaporating the condensate, and recovering the ammonia from the adsorber by heating a part of the hydrogen and using it as the regenerating gas for the adsorber, the heat for heating the hydrogen preferably being provided by combusting a part of the evaporated condensate recovered from the cryogenic partial condensation.

Abstract: A process is disclosed for recovering hydrogen from an ammonia synthesis plant comprising(a) cooling a high pressure stream of said purge gas to a sub-ambient temperature at which substantially all of the methane and argon contained in said purge gas stream and a portion of the nitrogen condense,(b) expanding liquid and vapor components of the cooled high pressure stream to an intermediate pressure,(c) phase separating liquid and vapor components of the cooled and expanded purge gas stream,(d) expanding separated liquid component from step (c), and(e) heating expanded separated liquid component from step (d) and separated vapor component from step (c) in heat exchange with said high pressure stream of purge gas to cool the latter.