Advanced exergy analysis applied to an externally-fired combined-cycle power plant integrated with a biomass gasification unit

An advanced exergy analysis is reported for a recently developed configuration of an externally-fired combined-cycle power plant integrated with biomass gasification. The results identify the potential for improvement of the overall system considering interactions among the components. It is found that interactions between the components are not very strong, i.e. the endogenous exergy destruction within each component is higher than the exogenous ones. Also, the advantages are demonstrated of advanced exergy analysis over conventional exergy analysis; it is concluded that the focus for improving cycle performance should be on the heat exchanger and not the combustion chamber or gasifier, even though these have the highest exergy destructions among all the components. In addition, it is concluded that the unavoidable part of exergy destruction in almost all components is higher than the avoidable value. Therefore little can be done to reduce the irreversibilities for components of the externally-fired combined-cycle power plant.