Exergy analysis on biomass based methanol and power polygeneration system

A new kind of biomass based polygeneration system for the production of power and methanol is proposed in this paper. The most attractive feature of this proposed system is the elimination of shift reaction and the adoption of partial-recycle of unreacted syngas. The thermodynamic performance of the system was examined and compared to those of two biomass-based reference individual systems: The individual biomass to methanol system with shift process and biomass integrated gasification combined cycle. The influence of important factor recycling ratio of unreacted syngas (Ru) which will determine the exergy ratio of chemical product to power (γ) was also investigated. From the synergetic viewpoint of chemical conversion and energy utilization, with and without shift reaction and different treatments of unreacted syngas were also discussed. The evaluation results show that the new polygeneration system can reduce energy consumption by as high as 10 percentages compared to the individual systems. Moreover, the proposed polygeneration system would be expected to realize the synergetic combination of chemical conversion and efficient utilization of chemical energy of biomass, and offer a possibility of developing new technologies for biomass-based systems.