Design and performance analysis of a coal-fired power plant integrated with high and low temperature molten salt thermal storage for improving peaking capacity

In order to improve the peaking performance of the coal-fired power plant (CFPP), this paper proposes a scheme, which integrates a CFPP with the high-temperature and low-temperature molten salt thermal storage. Two different types of molten salt thermal storage systems can increase the temperature range of heat storage and improve system efficiency and peaking performance compared to the existing single molten salt thermal storage. In the energy storage process, high-temperature molten salt (Solar salt) and low-temperature molten salt (Hitec salt) are used to store the thermal energy of the main steam and reheat steam in the CFPP. In the energy release process, high and low-temperature molten salts are used to heat the feedwater and condensate. The system integration can effectively broaden the peak range of the CFPP. The thermodynamic model of the coupled system is constructed and the system performance is analyzed from the perspectives of thermodynamics and economy, respectively. The results show that the peak range of CFPP is from 18.39 % THA to 106.35 % THA, the equivalent round-trip efficiency of the newly built CFPP is 54.69 %, and the exergy efficiency of the coupled system is 37.43 %. In addition, for the addition of the MSTS to the in-service CFPP, the net present value (NPV) is 107752.70 k$ and the dynamic payback period (DPP) is 3.63 years. For the newly built CFPP with MSTS, NPV is 661960.93 k$ and DPP is 7.90 years. This paper may provide a feasible scheme to improve the peaking performance of the coal-fired power plant.