Exergy and exergoeconomic analyses with modeling for CO_2 allocation of coal-fired CHP plants

摘要

The coal-fired power plant is confronted with severe challenges due to increasing coal price and negative impact on climate change. In this study, exergy and exergoeconomic analyses of a 330 MW coal-fired combined heat and power (CHP) plant are performed to determine the unit exergoeconomic cost and specific CO2 emission of the final products. The cycle is simulated by Aspen Plus software and thermodynamic properties under different conditions are extracted. Exergy balance equations are formed based on the exergy flow of coal, water/steam, ash, and flue gases. Cost formation process has been revealed by the exergoeconomic analysis combining the recent development of residue cost allocation. Different from previous studies, cost of flue gas cleaning is taken into account as a part of the unit exergoeconomic cost of the products. Moreover, CO2 allocation is conducted based on the exergoeconomic model and has been compared with other methods. Results show that the largest exergy destruction occurs in the boiler and the lowest exergy efficiency occurs in the low-pressure heater. There is an energy-saving potential of the residue exergy which accounts for 7.5% of the exergoeconomic cost in heating period and 10.4% in non-heating period. (C) 2018 Elsevier Ltd. All rights reserved.