Process intensification in PSA processes for upgrading synthetic landfill and lean natural gases

Process intensification aims at reducing the size of equipment by orders of magnitude and is actively perused in separation processes. Its feasibility in Pressure Swing Adsorption (PSA) processes has been explored. A 4-bed PSA and a 3-bed PSA, which emulate the moving bed processes, and duplex PSA and a modified duplex PSA have been selected for the exploratory studies. Simulation studies on the separation of a mixture of CH4–CO2 over 5A zeolite were carried out to compare the performance of these processes. An index has been proposed to quantify the process intensification. The 3-bed PSA and the modified duplex PSA exhibited superior performance compared to the other two for a purity of 99.9 mol% of both the products. However, the performances of the processes other than duplex were comparable when purities were set at 95 mol%. In 3-bed PSA a modest process intensification of four times reduction in size and two times reduction in energy requirement appears to be feasible if benchmarked against the PSA based on the variant of the Skarstrom cycle.