Method of recovering enriched gaseous oxygen

A process for recovering oxygen-rich gas by enriching gaseous oxygen contained in crude gas by a single tower pressure swing adsorption which utilizes a single adsorption tower loaded with an adsorbent, the adsorption tower having a crude gas inlet and a product gas outlet, the process comprising repeating a cycle which includes:

• an adsorption step for adsorbing an unnecessary gas component contained in the crude gas by the adsorbent by introducing the crude gas into the adsorption tower to output oxygen-rich gas from the adsorption tower;
• a desorption step for desorbing the unnecessary gas component from the adsorbent by depressurizing the adsorption tower;
• a washing step for introducing washing gas into the adsorption tower to discharge remaining gas from the adsorption tower;
• and
• a pressurization step for raising internal pressure of the adsorption tower;
• wherein the desorbing step includes a first desorption sub-step performed immediately after the adsorption step for recovering semi-enriched oxygen gas existing in the adsorption tower through the product gas outlet for retention in a recovery tank while discharging the unnecessary gas component desorbed from the adsorbent through the crude gas inlet under pressure reduction, and a second desorption sub-step performed immediately after the first desorption sub-step for discharging the unnecessary gas component desorbed from the adsorbent through the crude gas inlet under pressure reduction with the product gas outlet closed;
• wherein the washing step includes a first washing sub-step for introducing part of the oxygen-rich gas as the washing gas into the adsorption tower through the product gas outlet while discharging the remaining gas from the adsorption tower through the crude gas inlet, and a second washing sub-step for introducing part of the semi-enriched oxygen gas retained in the recovery tank as the washing gas into the adsorption tower through the product gas outlet while discharging the remaining gas from the adsorption tower through the crude gas inlet;
• and
• wherein the pressurizing step includes raising the internal pressure of the adsorption tower by introducing the rest of the semi-enriched oxygen gas retained in the recovery tank into the adsorption tower through the product gas outlet.