Removal of water and carbon dioxide from air

Claim 1

The process of removing water and CO 2 from an air feed stream containing the same, which comprises the steps of: introducing the air stream at superatmospheric pressure into a first bed of solid adsorbent effective in adsorption of water from said feed air stream, discharging the dried air from the first bed and introducing a major portion thereof into an initial second bed containing adsorbent effective in retention of CO 2 , collecting the clean dry air thus obtained as product gas; regenerating said first bed after a relatively short on-stream operating period and, during said regenerating of said first bed, introducing the air feed stream into a companion parallel bed of similar composition as said first bed and operated in alternating sequence therewith, the regeneration of said first bed being effected by the sequential steps of: (a) reducing the pressure at the air feed inlet of the bed thus venting at least voids gas from the bed, (b) purging the bed at the reduced pressure with a dry gas, and (c) introducing dried air discharged from said companion bed into the purged bed to bring said bed to initial superatmospheric pressure for further adsorption of water; said alternating introduction of feed air into said first bed and said companion bed being continued for a relatively long period while continuing to discharge dried air from said first bed and said companion bed each in turn to said initial second bed; independently regenerating said initial second bed after said relatively long on-stream period by the sequential steps of (d) depressurizing the CO 2 -laden bed by venting therefrom a gas effluent including voids gas, (e) elevating the temperature of the bed to drive off adsorbed CO 2 , (f) introducing cool gas into the bed to restore the same to near ambient temperature, and (g) bringing the cooled bed to its initial adsorption pressure level by introduction of dry CO 2 -free product gas.