Thermodynamic and economic analysis of a new methanol synthesis system coupled with a biomass integrated gasification combined cycle

An innovative design has been developed to optimize the performance of the methanol synthesis (MS) by integration with a biomass integrated gasification combined cycle (BIGCC) system based on the principle of the cascade utilization of chemical and thermal exergy. In the integrated system, the efficient utilization of the chemical energy present in feedstocks is made possible by combining exothermic MS chemical processes and integrating different grades of thermal energy. The graded conversion of methanol facilitates the manifestation of both its chemical and fuel attributes. By such incorporation, the waste heat and purge gas in MS process are utilized in a more efficient way and the biomass consumption in BIGCC plant is significantly reduced. A thermodynamic analysis conducted on a 100 kt/yr methanol production plant and a 41.8 MW BIGCC power plant reveals an increase in energy efficiency of 3.46 % and an achievement of 61.9 % exergy efficiency. Moreover, this design yields a profit of 72.6 M$ more than that generated by individuals throughout its lifespan. Sensitivity analysis further indicates that the optimal conditions for the polygeneration system are approximately 250 °C and 60 bar, with a preference for a 0.90 MS recycle ratio. •An improved methanol synthesis integrated with a BIGCC system is proposed.•Purge gas and inerts from methanol synthesis are utilized more efficiently.•Effect of methanol synthesis recycle ratio is deeply studied.•Higher polygeneration efficiency and profitability are attainable.