Process simulation and analysis of air separation for oxygen production via fast vacuum swing adsorption

Abstract Fast pressure swing adsorption (FPSA) is an adsorption-based separation process with cycle durations ranging from a few to tens of seconds. While widely used in small-scale oxygen generators, FPSA still holds significant potential for improvement. In this study, we propose and demonstrate a novel rapid vacuum swing adsorption (FVSA) cycle, where adsorption occurs at atmospheric pressure and desorption under vacuum, to enhance small-scale oxygen production from air. A simulated air mixture, containing 78% nitrogen (N 2 ), 21% oxygen (O 2 ) and 1% argon (Ar), was processed through a dual-column FVSA system using LiLSX zeolite as the adsorbent. A numerical model was developed on Aspen Adsorption and validated against previously reported results. A parametric study was conducted to assess the effects of various operating conditions on separation performance. The results indicate that a low feed flow rate, low desorption pressure, and an optimal length-to-diameter ( L/D ) ratio improve the separation efficiency. Under operating conditions of 101.1 kPa adsorption pressure, 40.3 kPa desorption pressure, and a feed rate of 47 L/min, the system achieved a 91% O 2 product stream with a 5 L/min flowrate and 44% O 2 recovery. Compared to traditional FPSA, FVSA reduced energy consumption by 13% (39.24 vs. 33.99 kJ·mol −1 O 2 ) and lowered the air-to-oxygen ratio by 25% (14.4 vs. 10.8) while maintaining comparable O 2 purity, demonstrating its potential for more efficient oxygen production.