Process simulation of bio-dimethyl ether synthesis from tri-reforming of biogas: CO2 utilization

Highlights: • The suitable condition of biogas tri-reforming for DME synthesis was studied. • The CO₂ from DME synthesis unit was used in tri-reforming to highly utilize CO₂. • H₂ and CO yields of tri-reforming enhanced at higher CO₂ recirculation ratio. • The system with H₂O and CO₂ removals from syngas can improve system efficiency. -- Abstract: The main contributions of this work are to study the suitable condition of biogas tri-reforming for DME synthesis process and to design the systems of the biogas tri-reforming process coupling with the DME synthesis. The effects of operating parameters in terms of boundary of carbon formation, steam to carbon ratio, and oxygen to carbon ratio on the biogas reforming process are firstly investigated. To utilize more CO₂ in the system, CO₂ produced from the DME synthesis is recycled to use in the biogas tri-reforming process. The H₂ and CO yields of the tri-reforming process increase with increasing the CO₂ recirculation ratio while the DME yield and system efficiency decrease. The requirement of gas cleaning unit for the DME synthesis coupling with the biogas tri-reforming system is also analyzed. The results indicate that the system with CO₂ removal from syngas has more impact on the DME yield than that with H₂O removal. On the contrary, the total CO₂ emission intensity of the system with H₂O removal is lower than that with CO₂ removal. When comparing all cases, the system with both H₂O and CO₂ removals achieves the highest DME yield and system efficiency.