Process for the production of a gas with a substantial oxygen content

In a process for the production of a gas with a substantial oxygen content by adsorption of nitrogen from air, with a plurality "n" of adsorbers, wherein there is successively and cyclically assured according to a period T, in each of said adsorbers, with a time offset of T/n, from one adsorber to the next:

• a) a production stage of said gas with a substantial content of oxygen by withdrawal of gas in a direction called co-current at high pressure, with admission of air;
• b) a depressurization stage incorporating a counter-current terminal pumping phase under a sub-atmospheric pressure to a minimum pressure of the cycle, of the order of 0.2.times.10.sup.5 Pa absolute;
• c) a repressurization stage incorporating a final counter-current repressurization with a gas enriched in oxygen;
• d) the number of adsorbers (n) and the respective durations of said stages being such that at any moment at least two adsorbers are in the pumping phase of the depressurization stage, at different pressure levels;
• the improvement wherein:
• e) the pumping phase is subdivided into a plurality of pumping sub-stages, all of the same duration equal to T/n, or to a sub-multiple of T/n, and each pumping sub-stage is associated with pumping means specific to the conditions of flow rate and pressure variation of said sub-stage;
• f) each pumping means is immediately switched with an adsorber at the end of the sub-stage associated with said pumping means, to an adsorber at the beginning of said sub-stage.