Two-Dimensional Modeling of Pressure Swing Adsorption (PSA) Oxygen Generation with Radial-Flow Adsorber

Xiong Yang,Yi Xing,Haoyu Wang,Jiangwei Chen,Ziyi Li,Chuanzhao Zhang,Yingshu Liu

doi:10.3390/app9061153

Abstract

Radial flow is an important type of flow direction for large-scale pressure swing adsorption (PSA) oxygen generation systems. In this study, a numerical simulation of a PSA oxygen generation process based on radial-flow adsorbers was performed with two-dimensional CFD modeling. The gas distribution, the maldistribution factor and the pressure difference were comparatively investigated at each flow type of the radial-flow adsorber. Considering the gas adsorption performance, the results indicated that the centripetal π-flow radial adsorber has the best flow characteristics for the PSA process. The oxygen purity distribution within the adsorption bed was studied to compare centripetal and centrifugal π-flows, and the former was shown to perform better on oxygen enrichment and adsorbent desorption. The steady state was achieved after eight cycles for the centripetal-π adsorber and each of the four steps of the PSA process was explored in detail to show the advantageous properties for oxygen generation in terms of adsorption and desorption. The relationships between the product flow rate and the oxygen purity and recovery were further investigated.

Highlights

Large-scale pressure swing adsorption (PSA) oxygen generation systems have attracted considerable attention in recent years due to the low cost [1] and increasing demand for industrial gases
Vertical radial-flow adsorbers are widely used in the purification process of large-scale cryogenic air separation systems [6,7] and used on the large scale of PSA
It can be seen that the four radial-flow adsorbers give similar patterns of pressure changes with the order of the value of CF-π>CF-Z>CP-Z>CP-π, indicating that the effect of the flow type on the pressure change in the bed during the radial-flow PSA process is small

Summary

Introduction

Large-scale PSA oxygen generation systems have attracted considerable attention in recent years due to the low cost [1] and increasing demand for industrial gases. In China, the pressure swing adsorption (PSA) oxygen generation scale has reached 40,700 Nm3 h−1 in the coal chemical industry. Due to the huge gas flow used in large-scale oxygen generation plants, diameters larger than 4–5 m are generally required in conventional axial-flow adsorbers, which exceed economical shipment limits. Such axial-flow adsorbers have inherently large void volume percentages in the upper and lower head spaces, and difficulties in flow distribution, leading to negative impacts on oxygen generation [2]. Vertical radial-flow adsorbers are widely used in the purification process of large-scale cryogenic air separation systems [6,7] and used on the large scale of PSA

Methods

Results

Conclusion