Experiment and simulation study of a dual-reflux pressure swing adsorption process for separating N2/O2

Abstract

Abstract A dual-reflux pressure swing adsorption (DR-PSA) process using LiLSX zeolite to produce both high purity and recovery of N 2 and O 2 from mimical air (21%O 2 /79%N 2 ) was developed in the commercial software, Aspen Adsorption. In this work, adsorption equilibrium isotherms of pure oxygen and nitrogen on LiLSX zeolite were firstly measured and fitted with the extended Langmuir model in order to describe the behavior of the static adsorption. A total of sixteen experiments were carried out on a laboratory scale DR-PSA apparatus for verifying the reliability of the mathematical model. Finally, an optimal operating condition was obtained by comparing the purity and recovery of products under different experimental conditions. Results revealed that feed or light reflux time (t FE/LR ), heavy reflux flow rate (Q HR ), vacuum pressure (P L ) and feed flow rate (Q F ) all had significant effects on the process performance. O 2 in light product could be enriched to 99.1% with recovery of 98.0% while N 2 in heavy product is 99.0% in concentration with recovery of 99.3% under the optimal experimental condition. All in all, the DR-PSA process could be capable of producing both heavy and light products simultaneously with high purity and recovery.