Production of mixed gases of controlled composition by pressure swing adsorption

Claim 1

In the production of a binary gas mixture of desired fixed proportions of components from a starting feed gas containing such components, the method which comprisees the steps of (a) passing the feed gas at superatmospheric pressure into a bed of solid adsorbent preferentially selective in retention of a first of said components, while discharging from said bed as primary effluent a stream consisting essentially of the unadsorbed or less selectively adsorbed second component; (b) while said bed is at about the aforesaid superatmospheric pressure, discontinuing said feed gas introduction and rinsing the bed, in a direction co-current to that of the feed gas introduction, with a gas stream rich in said preferentially retained first component; (c) withdrawing contained gas from said bed until said bed is depressurized to about a pressure level P and compressing at least a part of the gas so withdrawn to about superatmospheric level for use as rinsing gas in step (b); (d) while at about said pressure level of P, purging the bed with a controlled amount of the gas discharged as primary effluent during step (a), thereby producing a purge effluent as the binary gas mixture of desired fixed proportions of components; and thereafter (e) repressuring the bed to the initial superatmospheric pressure level of step (a) for repetition of the recited sequence of steps, said repressuring being effected with part of the primary effluent from step (a).