| 摘要 |
<p>In an improved process for the pre-purification of air upstream of its introduction into a cryogenic air separation unit water vapour and carbon dioxide are removed from air by a pressure swing adsorption (PSA) process utilising an adsorbent which has an initial layer of activated alumina comprising from about 70% to 100% by volume of the bed with the remaining layer, if present, being a suitable zeolite. The particles of adsorbent, particularly the zeolite, have a particle size not greater than 2mm. Two beds (A,B) or adsorbent are employed. While one bed produces purified air, the other is vented to the atmosphere and then purged by impurity free gas to regenerate it. Both regeneration steps involve flow of gas through the bed countercurrent to the air flow during the production step. After purging, the bed being regenerated is repressurised by being fed (at its product gas end) product gas from the other bed. <IMAGE></p> |
