Modelling Cryogenic Pressure Swing Adsorption for Methane and N2 Separation for Natural Gas Purification

Natural gas is processed to control purity and bring it to sales standard. A part of this processing involves the removal of N2 and CO2 which may exist in large quantities in the gas. These impurities are often removed using Cryogenic Pressure Swing Adsorption (CPSA). PSA uses pressure changes to maximise the efficiency of adsorption and desorption. A fundamental mathematical model was developed in MATLAB to describe the adsorption phase of CPSA. This model included simulation of the flow patterns in the column, and the diffusion and adsorption processes occurring in the adsorbent particles to produce information on the composition at the outlet of the column over time. The results of the model were compared to experimental data. The culmination of these four steps was a model that produces relatively accurate results at cryogenic temperature (192K). However, the output when compared to non cryogenic temperature data (at 303K) was less accurate.