Patent ID: 7645325

Claim:
A method of making oxygen with three-stage pressure-swing adsorption device, wherein oxygen and nitrogen are separated from air; the production can be oxygen or nitrogen or both of them; the method adopts three-stage pressure-swing adsorption device operating in series, wherein the first stage pressure-swing adsorption device is used to remove carbon dioxide and water as well as partial nitrogen and enrich nitrogen, the second stage pressure-swing adsorption device is used to further remove the nitrogen in interim gas which is discharged from the adsorption tower in the adsorption step of the first stage and increase the concentration of oxygen up to the desired level, and the third stage pressure-swing adsorption device is used to further remove the nitrogen and argon in oxygen-enriched gas mixture which is discharged from the adsorption tower in the adsorption step of the second stage and increase the concentration of oxygen up to above 95V %; the adsorption tower of the first stage sequentially undergoes the following steps in one circulation period: adsorption A, purge P′, evacuation VC, the second stage gas backward equalization repressurization 2ER, purge gas repressurization R′, final repressurization FR; the adsorption tower of the second stage sequentially undergoes the following steps in one circulation period: adsorption A, backward equalization depressurization BD′, final repressurization FR; the adsorption tower of the third stage sequentially undergoes the following steps in one circulation period: adsorption A, oxygen product purge P′, oxygen product depressurization D, and purge gas repressurization R′.