A modified specific fuel consumption analysis for predicting the rearrangement ofenergy system structures

Abstract

One variation of exergy analysis, specific fuel consumption (SFC) analysis, was modified according the advanced exergy analysis, where exergy destructions within each component were split into endogenous/exogenous and avoidable/unavoidable parts, and by combining the energy-savings effects of each component. The modified analysis approach can help locate not only the weak points at the component level but also certain bottlenecks from the topology viewpoint, which may indicate adding or deleting some components, or enhancing the thermodynamic interactions between different process or subsystems. The modified approach was then applied to a conventional coal-fired power plant. The detailed spatial distribution of SFC within the current system at different partial-load conditions were deeply discussed at both component and process levels. Further splitting of SFC and the energy-saving effects of each process are also obtained and discussed. The results show that combustion and heat-and-mass transfer processes have the largest SFC. Heat-and-mass transfer process and the vent process have the greatest avoidable SFCs. The closer the component to the final product, the larger its influence on the overall performance, and, thus, a small improvement to these components may lead to a large reduction in the overall fuel consumption. More effective energy-saving measures of coal-fired power plants should focus on the match of heat transfer at intermediate-and-low temperature level and the breakage of the isolation of heat transfer subsystems, especially enhancing the interaction between the air preheating process and feedwater preheating process.