Abstract: A process and a system for purifying gas, such as air, before cryogenic distillation, in which at least one energy parameter, chosen from the flow rate of the regeneration gas entering and/or leaving at least one adsorber, the duration of the regeneration step and the regeneration temperature of the regeneration gas entering at least one adsorber, is controlled, modified and/or regulated depending on at least one operating condition chosen from the pressure of the gas to be purified entering and/or leaving at least one adsorber, the flow rate of the gas to be purified entering and/or leaving at least one adsorber, the temperature (Ta) of the gas to be purified entering at least one adsorber and the content of impurities contained in the gas to be purified entering at least one adsorber and depending on the thermal profile of the heat front output by at least one adsorber at the end of regeneration.

Abstract: A process is provided for supplying nitrogen from an on-site air separation plant providing at least oxygen as a product, which entails feeding an air feed stream to an instrument-air compressor which is oversized relative to compressed air needed to feed an instrument controlling the plant, feeding at least a portion of the compressed air stream from the instrument-air compressor to a nitrogen membrane separator, thereby providing a stream of nitrogen product, and venting an oxygen-enriched air stream from the membrane.