An improved water electrolysis and oxy-fuel combustion coupled tri-reforming process for methanol production and CO2 valorization

CO2 containing emissions from electric power plants are major contributors to the consistent rise of atmospheric CO2 concentration. The tri-reforming process has significant relevance as it converts non-inert components (CO2, H2O, O-2) of the flue gas (with co-feed as methane) to synthesis gas without the intervention of an energy intensive CO2 separation step. Subsequent synthesis gas conversion to methanol is an important consideration. The conventional process employed air-fuel combustion based power plant generated flue gas in the tri-reforming coupled methanol production process to valorize CO2. Subsequently, the oxy-fuel combustion and water electrolysis coupled tri-reforming based methanol production process was developed as an improvement over it. In this paper, further advancements have been made to this coupled process. The following contributions have been made: (i) modification of the coupled process to increase the throughput of the water electrolysis unit to provide an inlet oxygen stream to the tri-reforming process to supplement an oxygen deficient flue gas stream, (ii) analysis of the synergistic role of simultaneous oxygen and hydrogen inputs from the water electrolysis unit on the performance of the overall process, and (iii) proposition of limiting the oxygen input to the tri-reformer to thermoneutrality to avoid exothermicity related issues. The above propositions have been implemented and compared with the base case coupled process via simulation runs in Aspen Plus V11. The results demonstrated a substantial improvement in both CO2 valorization potential (by 13.40%) and profitability (by 31.59%) of the process.