Methane enrichment in biogas mixture using pressure swing adsorption: process fundamental and design parameters

Biogas is recommended to be a potential fuel source that can provide a continuous supply of compressed natural gas in forms of bio-compressed natural gas. Different technologies proposed to enrich methane in biogas mixture such as cryogenic process, membrane process, physical and chemical absorption, water scrubber, and pressure swing adsorption (PSA). PSA is guaranteed as gas purification technology in air separation, gas drying application, and hydrogen enrichment. Recently, PSA applications extended to include other areas such as the methane enrichment into biogas mixture. PSA is an efficient purification process owing to the low-energy penalty, low-installation and operation cost, and simple and safe operation. The optimization of the PSA process can follow two paths mainly adsorbent modification and/or developments in the PSA process design. This work outlines the fundamentals of the pressure swing adsorption unit by investigating the main innovative process engineering approaches that improved the performance of the PSA process. Previous research about the PSA, simulation, and experimental examination for biogas upgrading are also introduced and significant findings highlighted. Besides, the article discusses the impact of some parameters on the performance of the PSA process such as bed porosity, pressure and time of adsorption, sizing of PSA unit, and purge to feed ratio. In addition, the evaluation parameters of the PSA process have been presented. PSA technology is a versatile process and alternative to other enrichment technologies, we expect that it will remarkably contribute to the Biogas industry in the future. •Pressure swing adsorption (PSA) cycle design and principles have been critically reviewed.•Parameters of PSA design have been discussed.•Adsorption time should be closed to the adsorption breakthrough time.•Equalization step is essential for PSA process that works with high pressure.•In case of high CO2 adsorption rate, rinse step is important.