Techno-economic Analysis of the Syngas Conditioning from Biogas Using PSA and Pswa: Case Study of Methanol Synthesis

Abstract

The use of biogas as renewable source for syngas production has been gaining attention in recent years, representing an alternative clean and sustainable path from fossil fuels. Syngas is used as feedstock for a large number of chemicals and the required composition will be defined based on the desired product. Thus, a syngas conditioning step is essential to ensure the necessary stoichiometric ratio. This work analyses the use of pressure swing adsorption (PSA) and pressure swing water absorption (PSWA) units for the conditioning of the syngas to evaluate the impact of the use of cleaner carbon capture technologies. A 100 kmol/h biogas plant was simulated to evaluate the technical and economic aspects of the syngas synthesis process. Aspen HYSYS V11 was used to simulate the reforming and conditioning sections. As a case study, syngas for methanol synthesis was chosen. A sensitivity analysis on the most biogas composition was performed to study the impact on process costs and technical parameters. The results shows that the PSA is slightly less expensive, but the difference of overall costs is less than 2% between both technologies. In addition, the PSWA pathway showed a decrease in energy consumption with a biogas with higher methane content, while the PSA pathway maintained around the same energy consumption level.