Reduction of the adsorber size of a medical oxygen concentrator (MOC) employing a generic pressure swing adsorption (PSA) technology is an ongoing research and development activity. The MOC typically produces a 90À93% O 2 -enriched product gas from ambient air at a rate of e10 L/minute (LPM) for individual use. A common practice is to reduce the total cycle time (t c , seconds) of the PSA process in order to decrease the bed size factor [BSF, pounds of adsorbent in the PSA unit per ton of contained O 2 per day production rate (TPD c )]. Adsorbent columns packed with very small adsorbent particles are used to enhance the adsorption kinetics for rapid PSA cycle operation. An experimental mini-PSA set up was used to measure the performance of a simulated Skarstrom-like PSA cycle using a commercial sample of LiX zeolite as the air separation sorbent. Different adsorbent particle sizes, adsorption pressures, and cycle times were tested. It was experimentally demonstrated that BSF cannot be indefinitely reduced by lowering t c because of finite adsorbate mass transfer and gasÀsolid heat transfer resistances, as well as column pressure drop during the desorption step. A BSF of ∼25À50 lbs/TPD c with an O 2 recovery of ∼25À35% for production of ∼90% O 2 could be achieved by the PSA process using a dry, CO 2 -free air feed at a pressure of 3À4 atm, an adsorbent particle size of ∼0.35 mm, and a total cycle time of 3À5 s. A novel 'snap on' concept of a truly compact and portable MOC was proposed.

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Significance A nonequilibrium, nonisothermal, nonisobaric model was used for numerical simulation of the efficiency of N2 desorption from a LiX zeolite column by rapid purge with O2 in a pancake adsorber. The key parameters included desorption time, adsorbent particle size, and the adsorber length to diameter ratio. The efficiency was found to be a complex function of these variables.