Process simulation of single-step dimethyl ether production via biomass gasification

In this study, we simulated the single-step process of dimethyl ether (DME) synthesis via biomass gasification using ASPEN Plus™. The whole process comprised four parts: gasification, water gas shift reaction, gas purification, and single-step DME synthesis. We analyzed the influence of the oxygen/biomass and steam/biomass ratios on biomass gasification and synthesis performance. The syngas H₂/CO ratio after water gas shift process was modulated to 1, and the syngas was then purified to remove H₂S and CO₂, using the Rectisol process. Syngas still contained trace amounts of H₂S and about 3% CO₂ after purification, which satisfied the synthesis demands. However, the high level of cold energy consumption was a problem during the purification process. The DME yield in this study was 0.37, assuming that the DME selectivity was 0.91 and that CO was totally converted. We performed environmental and economic analyses, and propose the development of a poly-generation process based on economic considerations.