Mass Transfer in Nitrogen Pressure Swing Adsorption Plants: a Custom Model Based on Aspen Adsorption

In this work, a dynamic mathematical model was developed for the simulation of the pressure swing adsorption process (PSA), through the Aspen Adsorption software for the purpose of validation, optimisation, and control of the nitrogen generation in the PSA pilot plant located at the Fachhochschule Münster (Münster University of Applied Sciences), Faculty of Chemical Engineering - Steinfurt. The mathematical model for the description of the transport phenomena developed within the packed column filled by adsorbent material (CMS) was formulated through the application of several assumptions in the mass/momentum and energy balances, in order to generate inside the software a correct set of partial differential equations. Simulation studies were performed to investigate the effect of changing various process variables such as the duration of PSA cycle time, the heat effect, and pressure drop, in order to achieve higher purity (up to 10 ppm of residual oxygen). A comparison between simulation results of a dynamic model and experimental results were carried out to evaluate selected assumptions. The outcome showed that the model is reliable in some purity intervals while it is not entirely satisfactory when high purity is required (99.999 % nitrogen) because data for a detailed description of kinetics or transport phenomena are missing. Other possible reasons and future improvements were discussed at the end of this work.