Coke oven gas to methanol process integrated with CO₂ recycle for high energy efficiency, economic benefits and low emissions

Highlights: • CO₂ recycle assistance with COG to CH₃OH with dry reforming is proposed. • New process with dry reforming improves H₂ utilization and energy saving. • Process with H₂ separation (CWHS) is more preferable to CH₃OH output. • CWHS shows an excellent performance in energy, economy and CO₂ emission reduction. - Abstract: A process of CO₂ recycle to supply carbon for assisting with coke oven gas to methanol process is proposed to realize clean and efficient coke oven gas utilization. Two CO₂ recycle schemes with respect to coke oven gas, namely with and without H₂ separation before reforming, are developed. It is revealed that the process with H₂ separation is more beneficial to element and energy efficiency improvement, and it also presents a better techno-economic performance in comparison with the conventional coke oven gas to methanol process. The exergy efficiency, direct CO₂ emission, and internal rate of return of the process with H₂ separation are 73.9%, 0.69 t/t-methanol, and 35.1%, respectively. This excellent performance implies that reforming technology selection, H₂ utilization efficiency, and CO₂ recycle ways have important influences on the performance of the coke oven gas to methanol process. The findings of this study represent significant progress for future improvements of the coke oven gas to methanol process, especially CO₂ conversion integrated with coke oven gas utilization in the coking industry.