Argon purification

Claim 1

The method of purifying a crude argon stream containing minor amounts of oxygen and nitrogen which comprises the steps of: (a) during an adsorption step passing said stream as feed serially through a first bed of adsorbent preferentially selective in retention of nitrogen and during said adsorption step passing substantially the entire unadsorbed gaseous effluent from said first bed directly into and through a physically separated second adsorbent bed kinetically selective in adsorption of oxygen, while recovering from said second bed the discharged argon product stream of enhanced purity; then regenerating both said beds by; (b) simultaneously evacuating said first and second bed in a direction counter to step (a); then (c) while continuing said evacuation of said first bed only, repressuring said second bed in a direction counter to that of the feed with a portion of the purified argon product recovered in step (a); then (d) repressuring said first bed with purified nitrogen-depleted argon product from a companion first bed; then (e) again subjecting the first bed to step (a); the foregoing steps being carried out in preset time sequence in a system comprising a plurality of such first beds operated cyclically in parallel and a lesser plurality of such second beds operated in parallel, so arranged that the said second beds undergo in sequence, the steps of (a) receiving crude argon, (b) evacuation and (c) repressuring, a larger number of cycles during a given time period than said associated first beds.

Claim 2

The method of purifying a crude argon stream containing minor amounts of oxygen and nitrogen which comprises the steps of: (a) during an adsorption step passing said stream as feed serially through a first bed of adsorbent preferentially selective in retention of nitrogen and during said adsorption step passing substantially the entire unadsorbed gaseous effluent from said first bed directly into and through a physically separated second adsorbent bed kinetically selective in adsorption of oxygen, while recovering from said second bed the discharged argon product stream of enhanced purity; then regenerating both said beds by; (b) simultaneously evacuating said first and second bed in a direction counter to step (a); then (c) while continuing said evacuation of said first bed only, repressuring said second bed in a direction counter to that of the feed with a portion of the purified argon product recovered in step (a); then (d) repressuring said first bed with purified nitrogen-depleted argon product from a companion first bed; then (e) again subjecting the first bed to step (a); the foregoing steps being carried out in preset time sequence in a system comprising a plurality of such first beds operated cyclically in parallel and a lesser plurality of such second beds operated in parallel, so arranged that the said second beds undergo in sequence, the steps of (a) receiving crude argon, (b) evacuation and (c) repressuring, a larger number of cycles during a given time period than said associated first beds.

Claim 6

The method as defined in claims 1 or 2 wherein step (a) is continued for a preset time period such that there is a breakthrough from said first bed of product containing about 3 ppm nitrogen.