1.05 MW molten salt furnace experimental investigation of full-conditional thermal energy storage for the transfer and storage of waste heat from blast furnace gas

This paper proposes the use of heat storage devices and technologies to convert the unstable heat of gas generated by the iron and steel industry into stable heat, thus realizing the controllable and stable utilization of the gas waste heat. To this end, a 1.05 MW molten salt furnace energy storage experimental system was developed, utilizing a spiral coil type molten salt furnace to heat solar salt and achieve energy transfer and storage. The study comprehensively analyzes the preheating, heating, cooling, and special working conditions of the molten salt furnace. The experimental results demonstrate that the coils can be preheated within 150 min and heats the solar salt to over 570 °C at the rated load. However, the vertical and axial directions of the coil exhibit varying degrees of thermal stress under different operating conditions. In addition, the Reynolds number and Nusselt number of the heat transfer process were calculated and the convective heat transfer correlation equation was fitted using the similarity principle to find the heat transfer efficiency of the molten salt furnace of 77.12 %. These findings are expected to address the waste blast furnace gas issue and contribute to developing a sustainable energy system in the steel industry.