Operational flexibility enhancement of a combined heat and power plant supplying industrial steam: The integration of sensible or sensible-latent heat storage system

Abstract

The increasing penetration of renewable energy requires greater operational flexibility of thermal power plants, as dispatchable power sources are essential to balance the power supply and demand sides. However, the CHP plant has restricted load cycling range due to its heat dominated operation mode. The Integration of a high-temperature heat storage system is a potential solution to enhance the operational flexibility of the CHP plant that cogenerates industrial steam and power. However, the optimal design of the heat storage system integrated within a CHP plant is complicated due to the changing operation conditions and various heat exchanging mediums. In this study, the design method of the sensible or sensible-latent heat storage system integrated with a CHP plant supplying industrial steam was proposed. The simulation, exergy analysis and economic analysis models were developed, and a case study of 350 MW CHP plant was conducted. The maximum CHP plant output power decrement is 13.59 MW when the heat of flue gas and main steam is stored in the sensible or sensible-latent heat storage system. The exergy-to-exergy efficiencies of sensible and sensible-latent heat storage systems are 71.60 % and 77.76 %, respectively. However, the economic analysis results show that the sensible heat storage system is more cost-effective than the sensible-latent heat storage system.