A method for producing oxygen by adsorbing a stream of atmospheric air, using a VPSA, including at least one adsorber, each adsorber undergoing a single pressure cycle including the following steps: a) producing a first stream of gas having an oxygen content T1 while loading the adsorber of the stream of atmospheric air upstream; b) producing a second stream of gas including an oxygen content T2<T1: c) producing a third stream of gas including an oxygen content T3<T2<T1 while simultaneously extracting a nitrogen-enriched residual stream; d) eluting the adsorber, from which the three streams of gas produced in steps a), b), and c) are taken with the second stream of gas produced in step b); e) repressurizing the adsorber consecutively with at least two streams, first and second repressurizing streams, with increasing oxygen content.

The present disclosure relates to a pressure swing adsorption apparatus for high purity hydrogen purification from ammonia decomposition and a hydrogen purification method using the same, and more specifically, the pressure swing adsorption apparatus includes a plurality of adsorption towers including a guard bed unit and a hydrogen purification unit, in which each adsorption tower is packed with different adsorbents, to purify high purity hydrogen from mixed hydrogen gas produced after ammonia decomposition, make it easy to replace the adsorbent for ammonia removal, minimize the likelihood that the lifetime of the adsorbent in the hydrogen purification unit is drastically reduced by trace amounts of ammonia, efficiently recover hydrogen of the guard bed unit, thereby maximizing the hydrogen recovery rate compared to a conventional pressure swing adsorption process including a pretreatment unit and a hydrogen purification unit, and respond to a large change in ammonia concentration in the raw material.

Methods and systems for purifying argon from a crude argon stream are disclosed, employing pressure swing adsorption at cold temperatures from 186 C. to 20 C.; more preferably from 150 C. to 50 C.; and most preferably from 130 C. to 80 C. with oxygen-selective zeolite adsorbent. In some embodiments, the oxygen-selective zeolite adsorbent is a 4A zeolite, a chabazite, or a combination thereof.

A pressure swing adsorption process (PSA) comprising the following steps: feeding an input gas containing H.sub.2, CO.sub.2 and impurities through a CO.sub.2 adsorbent material in a pressure vessel under a high pressure; withdrawing a first H.sub.2-rich product gas due to adsorption of CO.sub.2 in the adsorbent material; setting the pressure to an intermediate pressure causing the adsorbent material to release a second gas stream; passing a CO.sub.2-rich purge stream through the adsorbent material, obtaining a purge gas; setting the pressure to a sub-atmospheric low pressure, so that a CO.sub.2-rich product gas is released under vacuum by the adsorbent material; re-pressurizing the vessel to said high pressure; said steps being performed cyclically in a pressure vessel or in a plurality of parallel pressure vessels of a multiple vessel setup.

The invention relates to a method for regulating a unit for separating a gas stream, having P adsorbers, where P2, each following a PSA-type adsorption cycle with a phase time shift, the method involving the steps of operating the unit according to the nominal cycle when the required flow rate is equal to a nominal flow rate or optionally when the required flow rate is higher than the nominal flow rate, and operating the unit according to the reduced cycle when the required flow rate is lower than or equal to a predetermined flow rate, the predetermined flow rate being lower than the nominal flow rate.