Application of rotating packed bed technology for biogas upgrading

School of Chemical and Metallurgical Engineering, Faculty of Engineering and Built Environment, Witwatersrand University, Johannesburg, South Africa

^* Corresponding author: atuman.joel@wits.ac.za

Abstract

Biogas is a renewable energy source consisting mainly of methane, carbon dioxide, and other impurities. A purification process is required to remove the impurities (biogas upgrading and purification) to meet the requirements as an energy source for vehicles. Removal of CO₂ from the biogas stream, which accounts for about 40% of the impurities, is necessary to produce biogas (mainly methane) for use in vehicles. Chemical absorption of CO₂ using a rotating packed bed was considered due to its high CO₂ absorption efficiency and small column size. Aspen Plus and Visual Fortran software were used to develop the model, and monoethanolamine (MEA) was used as the absorbent. The developed model was validated with experimental data, where the relative error is less than 10%. The process analysis performed shows: (a) biogas purity increases with rotation speed. (b) An increase in lean solvent concentration leads to an increase in CO₂ capture efficiency and biomethane purity. (c) An increase in biogas throughput leads to an increase in biogas purity. The study may be useful for the design and operation of intensified CO₂ capture from biogas streams for vehicle applications.