Parametric Study for Nitrogen Separation from Air by Pressure Swing Adsorption Using Carbon Molecular Sieve

Abstract

The separation of air by carbon molecular sieve (CMS) adsorption was studied in this work over a range of adsorption pressure of (2–8) bar. Breakthrough curves showed no significant effect of the pressure on product nitrogen purity and adsorbent capacity above 4 bar. Maximum purity of about 98% is observed for time up to 60 s. Adsorbent capacity obtained is in agreement with multicomponent Langmuir isotherm up to 4 bar. Maximum constant adsorbent capacity of about 0.1 mol O2/kg CMS is obtained for pressure above 4 bar.For PSA two columns 6-steps process, no significant effect of the pressure on the product purity above 4 bar. The purity increases with decreasing the productivity. Maximum purity of 97.6% is obtained at productivity of 156 lit/kg CMS.hr, cycle time of 100 s, and purge flowrate of 1 lit/min. The productivity of 606 lit/kg CMS.hr is obtained at purity of 94%, cycle time of 60s, and purge flowrate of 4 lit/min.