Cyclic Steady-State Axial Temperature Profiles in Multilayer, Bulk Gas PSAThe Case of Oxygen VSA

Both pressure swing adsorption (PSA) and vacuum swing adsorption (VSA) processes are often characterized by the slow evolution of temperature profiles to cyclic steady state (CSS). Perhaps most profound is the severe axial temperature profile that characterizes oxygen VSA occurring at the interface between a prelayer and the main adsorbent layer. This temperature profile or “cold spot” has been of much interest to the gas industry and adsorption researchers. Previous work (Wilson, S. et al. Ind. Eng. Chem. Res. 2001, 40 (12), 2701) has developed qualitative explanations of these temperature profiles. This paper describes a detailed experimental investigation of the process parameters that affect the axial CSS temperature profile in oxygen VSA. These experimental results are compared with a numerical model of the process and a simple predictive model. A conclusion of this work is that numerical models can accurately capture the CSS temperature profiles and that the simple model can account for some, but not all, of the observed effects. A better understanding of thermal profiles is necessary for the development of new thermal optimization strategies in oxygen VSA.