Abstract: The selective adsorption of nitrogen from air is used in a system including a number of adsorbers, to give oxygen enriched gas at elevated pressure, the adsorber is regenerated by depressurization under atmospheric pressure with a pump and by repressurization with oxygen enriched gas. The pumping duration is at most equal to the duration of the production step.

Abstract: The adsorber of the type comprising annular superposed beds, contains in its upper zone, a device to maintain and compress the upper bed, a flexible impervious membrane which separates the lower bed from the upper bed in its intermediate zone, and a cylindrical wall defining an internal annular duct for the lower bed in its lower zone. Application for example to the production of oxygen.

Abstract: A method of adsorption separation of gases of the kind which regenerates the adsorbant by pressure viariation and used two adsorbers, wherein the recompression stage includes at least one recompression stage using the oxygen produced, and a final recompression stage up to the high point of the cycle pressure using air intake without draw-off; and wherein the pressure high-point of the cycle is selected between 1.2 and 2 .times.10.sup.5 Pa and the pressure low-point is selected between 0.3-0.7.times.10.sup.5 Pa, at least the final part of the desorption stage being carried out by pumping. The method is essentially relevant to the production of oxygen.

Abstract: Gaseous oxygen is produced under a medium pressure which is higher than atmospheric pressure, and lower than a so-called high pressure. The medium pressure may also vary with time after which gaseous oxygen is brought to the high pressure. Each of the adsorbers of a high pressure PSA (Pressure swing Adsorption) adsorption device, undergoes a cycle including the following stage: (a) a stage of first pressure surge from a low pressure of the low pressure cycle to the medium pressure, during which oxygen under a medium pressure is introduced at a first end or outlet end, of the adsorber; (b) a stage of second pressure surge up to the high pressure; (c) a stage of production under high pressure, during which a gas substantially below the high pressure containing at least one component which is more easily adsorbed than oxygen, is introduced through a second end, or inlet end of the adsorber the gas being for example air, the first end being open; and (d) a stage of decompression to the low pressure of the cycle.