New combined supercritical carbon dioxide cycles for coal-fired power plants

Abstract

Supercritical CO2 (S-CO2) power cycle has been proven to be an efficient way to improve the efficiency of the coal-fired power plants. In this paper, new combined S-CO2 power cycles for coal-fired power plants were proposed to improve the performances of S-CO2 power cycle. A numerical model of S-CO2 cycle for coal-fired power plants was implemented. The effects of the key operating parameters on the performance of the new combined S-CO2 power cycles are numerically investigated and exergy destruction in each component is analysed. As a result, it can be found that the net cycle efficiency and specific power are improved by the new combined cycles, meanwhile the flue gas temperature is reduced. In contrast to the reference cycle, the net cycle efficiency and specific power of the combined Brayton cycle can be increased by 1.6% and 14.9 kJ/kg, respectively. Furthermore, the cycle exergy efficiency can be improved by 2.34%. As a result, a new insight is introduced for the development of S-CO2 Brayton cycles for coal-fired power plants.