Assessment of heat-to-power ratio in a bio-oil sorption enhanced steam reforming and solid oxide fuel cell system

摘要

A solid oxide fuel cell (SOFC) is a high-efficiency technology for combined heat and power (CHP) generation. Heat and power production can be varied according to changes in heat and power loads, which affect the electrical and thermal efficiencies. This study analyzes changes in heat and power production rates of a bio-oil sorption enhanced steam reforming (SESR) and SOFC system. The variations in the stack-to-burner ratio (bio-oil split fractions), fuel utilization factor (U-f), and recirculation ratio (R) are investigated. The effect of heat-to-power ratio on the system performance and CO2 capture efficiencies is also studied. Moreover, the benefit of the implementation of a bio-oil SESR and SOFC system over a conventional operation to match the energy demand for an industrial case is evaluated. The results reveal that an increase in U-f decreases the operating range of the heat-to-power ratio. On the other hand, the anode gas recirculation ratio affects such a parameter when the system performs at the high stack-to-burner ratio. A higher heat-to-power ratio increases the stack electrical and thermal efficiencies, leading to a higher CHP efficiency. The heat-to-power ratio of the proposed system varies between 0.05 and 7.5. However, to attain a CO2 capture efficiency higher than 50%, the heat-to-power ratio should be lower than 1.5. By comparing the two operational strategies: fixed heat-to-power ratio, and variable heat-to-power ratio, it is found that the heat-to-power ratio is an important factor for energy management. The primary energy saving is enhanced when the system is operated to satisfy the rates of heat and power demand.