Preparation of high purity oxygen

Claim 1

The method for producing and recovering from ambient air in a single stage operation an oxygen product of at least 95% purity, which comprises the sequence of steps: (a) passing the ambient air at superatmospheric pressure of up to about 8 atmospheres, successively through a bed of solid desiccant into and through a second bed in gas flow communication therewith comprised of an adsorbent selective for retention of nitrogen as opposed to oxygen, while discharging from said second bed and collecting as primary effluent an oxygen-rich product substantially freed of nitrogen at substantially the feed gas pressure a portion of which is presently removed from the process as said oxygen product of 95% purity; (b) at the end of step (a) discontinuing passing of air into said beds and, without further gas introduction therein, reducing the pressure in said beds to about atmospheric level by gas withdrawal in a direction countercurrent to that of step (a) whereby contained gas flows through said adsorbent bed into and through the desiccant bed to discharge therefrom; (c) following the recited gas withdrawal evacuating said beds to a subatmospheric pressure level which is at or less than 5% of the superatmospheric level obtaining during step (a); and (d) restoring said beds to initial superatmospheric pressure level of step (a) by introducing into said beds oxygen-rich gas including a portion of the primary effluent collected during step (a) and directly thereafter initiating a new cycle in the recited sequence starting with step (a); each of said steps (c) and (d) being carried out to effect gas flow through the beds in a direction concurrent that of step (b).

Claim 2

The method for producing and recovering from ambient air in a single stage operation an oxygen product of at least 95% purity, which comprises the sequence of steps: (a) passing the ambient air at superatmospheric pressure of up to about 8 atmospheres, successively through a bed of solid desiccant into and through a second bed in gas flow communication therewith comprised of an adsorbent selective for retention of nitrogen as opposed to oxygen, while discharging from said second bed and collecting as primary effluent an oxygen-rich product substantially freed of nitrogen at substantially the feed gas pressure a portion of which is presently removed from the process as said oxygen product of 95% purity; (b) at the end of step (a) discontinuing passing of air into said beds and, without further gas introduction therein, reducing the pressure in said beds to about atmospheric level by gas withdrawal in a direction countercurrent to that of step (a) whereby contained gas flows through said adsorbent bed into and through the desiccant bed to discharge therefrom; (c) following the recited gas withdrawal evacuating said beds to a subatmospheric pressure level which is at or less than 5% of the superatmospheric level obtaining during step (a); and (d) restoring said beds to initial superatmospheric pressure level of step (a) by introducing into said beds oxygen-rich gas including a portion of the primary effluent collected during step (a) and directly thereafter initiating a new cycle in the recited sequence starting with step (a); each of said steps (c) and (d) being carried out to effect gas flow through the beds in a direction concurrent that of step (b).