Module Configurations of Membrane Gas Separation System for Effective Utilization of Biogas

摘要

Module configurations of membrane process substantially affect the biogas separation performances. In this article, the characteristics according to module configurations were investigated in terms of purity and recovery efficiency to improve the biogas availability through simultaneous utilization of carbon dioxide and methane. First, a single-stage permeation was tested, and methane having > 97% purity was recovered, but the recovery efficiency dropped to below 40%; the simultaneous recovery of methane and carbon dioxide was impossible due to a trade-off. In carbon dioxide recovery experiment, high-purity carbon dioxide was recovered as well as almost all the methane in the biogas at > 99% efficiency. In methane recovery experiment, high-purity methane (> 97%) was produced, but recovery efficiency decreased to < 71%. To improve methane recovery efficiency, low-quality gases (permeate gas of the second module, and retentate gas of the third module) were recycled to the feed; methane recovery efficiency subsequently improved, and high-purity carbon dioxide could be recovered at a high recovery efficiency. Finally, we discussed methods for effective biogas utilization according to module configurations.