Flexibility improvement of a coal-fired power plant by the integration of biogas utilization and molten salt thermal storage

Abstract

This study presents a novel method to enhance the flexibility of coal-fired power plant (CFPP). The suggested integrated system comprises a CFPP integrated with molten salt thermal storage system and a biogas combustion and its waste heat utilization system. Molten salt can be used to heat high-pressure feedwater and expel steam into the turbine, quickly increasing the output of CFPP. The waste heat from biogas combustion is used to charge the molten salt, and further waste heat is recovered by ORC. Comparative analyses reveal compelling advantages. The power generation can be rapidly increased by 6.8 %. A substantial 1,342.45 kW increase in power generation and an impressive 9.52 % enhancement in energy efficiency. Exergy analysis demonstrates a notable 9.52 % improvement in overall exergy efficiency. The system yields an annual net income of 10,083.51 k$, boasting an exceptionally low dynamic payback period of 1.798 years and a substantial net present value of 51,427.34 k$ over its 10-year operational span. This research enhances understanding of the use of molten salt thermal storage to increase the flexibility of CFPPs and the biogas utilization.