Parametric study of pressure swing adsorption process to purify oxygen using carbon molecular sieve

To produce O₂ with a high purity of 99+% and a high productivity from various oxygen-rich feeds, a parametric study was done on a six-step pressure swing adsorption (PSA) purifier using carbon molecular sieve (CMS). The cyclic performances of the PSA process such as purity, recovery, and productivity were compared under nonisothermal conditions. To study the effects of N₂ amount on the PSA purifier, various feeds with 90% O ₂ or more were experimentally and theoretically applied for the PSA process. Since N₂ plays a key role in product purity, the maximum purity of the PSA was 99% O₂ with 51.5% recovery from a higher nitrogen feed (O₂:Ar:N₂; 90:4:6 vol %) and 99.8% O ₂ with 56.9% recovery from a lower nitrogen feed (O ₂:Ar:N₂; 95:4:1 vol %) within the experimental range. The adsorption step time and feed flow rate served as key operating variables in the purification of the oxygen-rich feeds because the concentration wave fronts of minor impurities such as N₂ and Ar were controlled by kinetic selectivity. To produce 99% O₂ purity from feeds with various amounts of N₂, the optimum operating variables were set to maximize the recovery and productivity within the experimental ranges. A high feed flow rate accompanied by a short adsorption step time could increase both purity and productivity. Without any serious loss of recovery and productivity, the process could purify the feed with higher than 91% O₂ to the product with higher than 99% O₂. The nonisothermal model incorporating mass, energy, and momentum balance together with a concentration-dependent rate model could accurately predict the performance results.