Assessment of methanol and electricity co-production plants based on coke oven gas and blast furnace gas utilization

This study aims to develop an economically viable novel process with high thermodynamic efficiency for the co-generation of methanol and electricity from coke oven gas (COG) and blast furnace gas (BFG). For this purpose, two processes are proposed to utilize COG and BFG. In process A, syngas is obtained from COG reforming, and BFG, after providing the required heat for the reformer, is injected into the methanol synthesis reactor as a rich carbon source. In process B, in addition to the above-mentioned, additional hydrogen is injected into the methanol reactor to enhance carbon dioxide conversion. The performance of the proposed systems is evaluated using energy efficiency, exergy efficiency, net CO₂ emission, and total production cost. Results show that energy efficiencies for processes A and B are 53.53% and 72.8%, and their exergy efficiencies are 23% and 26%, respectively. Moreover, environmental analysis demonstrates that process B has a net CO₂ emission of −1.82 kg_CO2/kg_methanol, while for process A, this parameter is relatively higher, and it is positive. From the economic viewpoint, it is concluded that process B is more feasible, and the total production cost of methanol decreases by 87.62% compared to process A. Also, it can be deduced that in the case of utilizing additional hydrogen electricity and methanol production from COG and BFG is interesting from the thermodynamic and economic point of view, and due to negative net CO₂ emission, it is environmentally desirable, too.