Two stage pressure swing adsorption process which utilizes an oxygen selective adsorbent to produce high purity oxygen from a feed air stream

A two stage pressure swing adsorption process to produce high purity oxygen from a feed air stream comprising the steps of:

• (a) passing the feed air stream through a first stage adsorption zone containing one or more adsorbents selective for the retention of impurities comprising carbon dioxide and water to produce an impurity saturated adsorption zone and an impurity-depleted effluent stream;
• (b) regenerating the first stage adsorption zone via:
• (i) depressurizing the first stage adsorption zone to produce an impurity-containing effluent stream which is discarded as waste;
• (ii) purging the first stage adsorption zone with a first purge gas in order to purge the adsorption zone of any impurities comprising carbon dioxide and water still remaining in the adsorption zone at the end of step (b)(i) wherein the effluent stream from this step is discarded as waste;
• (iii) further purging the first stage adsorption zone with a second purge gas in order to purge the adsorption zone of any impurities comprising carbon dioxide and water still remaining in the adsorption zone at the end of step (b) (ii) wherein the effluent stream from this step is discarded as waste;
• and
• (iv) repressurizing the first stage adsorption zone with a repressurization gas;
• (c) passing the impurity-depleted effluent stream from step (a) through a second stage adsorption zone containing an adsorbent selective for the retention of oxygen to produce an oxygen saturated adsorption zone and an oxygen-depleted effluent stream wherein at least a portion of said oxygen-depleted effluent stream is used as the second purge gas in step (b)(iii);
• and
• (d) regenerating the second stage adsorption zone via:
• (i) rinsing the second stage adsorption zone with a first rinse gas consisting of essentially pure oxygen in order to purge from the adsorption zone any co-adsorbed or void space impurities comprising argon wherein at least a portion of the effluent from this step (d)(i) is used as the repressurization gas in step (b)(iv);
• (ii) further rinsing the second stage adsorption zone with a second rinse gas consisting of essentially pure oxygen in order to further purge from the adsorption zone any co-adsorbed or void space impurities comprising argon still remaining in the adsorption zone at the end of step (d)(i) wherein at least a portion of the effluent from this step (d)(ii) is used as the first purge gas in step (b)(ii);
• and
• (iii) depressurizing the second stage adsorption zone to produce an effluent stream containing said high purity oxygen wherein a portion of said effluent stream is used as the first and second rinse gases in steps (d)(i) and (d)(ii).