Abstract: A method for the removal from a feed gas stream such as air of at least two contaminating gas components such as water and CO.sub.2 features repeated cycles of operation the improvement which comprise: feeding a regenerating gas such as dry nitrogen at a higher temperature, e.g. 70.degree. C., in a direction counter-current to the feed direction in contact with the adsorbent to produce a heat pulse travelling in the counter-current direction to desorb the less strongly adsorbed second contaminating gas component from the downstream (with respect to the feed direction) portion of the adsorbent by TSA while at the same time desorbing the more strongly adsorbed second contaminating gas component from the upstream (with respect to the feed direction) portion of the adsorbent by PSA.

Abstract: A cryogenic air separation unit (ASU) provides flows of oxygen and nitrogen. The oxygen is used in a process such as COREX iron making or the partial oxidation of hydrocarbons, or in an oxycoal fuelled blast furnace, producing an off-gas containing useful components (H.sub.2 and CO) and carbon dioxide. The carbon dioxide is removed by pressure swing adsorption using nitrogen from the ASU as a regeneration gas and the purified off-gas becomes a feed gas to a further process such as production of iron by direct reduction of iron ore or the production of a NH.sub.3 making ammonia or is recycled into the first process as a feed gas.