Preliminary design assessment of supercritical CO2 cycle for commercial scale coal-fired power plants

Abstract

The concept of the supercritical CO2 power cycle has been widely proved to be effective by previous studies. However, more specific system layout and key components design analysis is still imperative to demonstrate the technology feasibility of large scale utility. In the present paper the technology adaption of supercritical CO2 power cycle for commercial scale coal-fired power plant was evaluated in terms of both the whole thermodynamic cycle layout and the preliminary assessment of key components. The effect of several key factors such as turbine inlet parameters, compressor inlet parameters and two split flow ratios were analyzed by an in-house code for the purpose of optimization design of a 300 MW commercial scale coal-fired power plant. Furthermore, the preliminary design assessment of key components such as boiler, turbomachines and compact heat exchangers were performed to demonstrate the technology feasibility of commercial scale utility. The results showed that the proposed cycle can achieve 50.2% net efficiency. However, in order to achieve this high efficiency, the key components should be carefully designed to meet the high standard requirements and coal-fired system integration constraints: For boiler, split flow economizer is required to fully recover the flue gas residual energy with over 500 °C. A highly effective compact heat exchangers with pinch temperature as low as 5 °C are mandatory. The compressors and turbines are also required to achieve the high industry level with compressors efficiency of 89% and turbines efficiency of 94%.