Abstract: In a process for the recovery of hydrogen from compressed purge gas withdrawn from a recyling gas stream of an ammonia synthesis wherein the hydrogen is separated from the purge gas by partial condensation at cryogenic temperatures,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 and apparatus for the separation of gases by preferential adsorption of at least one of the gases in which at least three adsorption zones are used, at least two of which are arranged in series to form the separation zone while at least one other is being regenerated for re-use in the separation zone, and in which periodically a fresh zone is added to the end of the separation section from which the product gas is recovered and the zone forming the first zone of the separation section is removed for regeneration whereby each zone is successively incorporated into the separation section and subsequently removed from it and regenerated ready for reincorporation into the separation section. Improved utilization of adsorbent and reduced loss of product gas for regeneration purposes is thereby achieved without loss of product purity.