Experimental Study On Molten Salt Melting And PLC Optimized Control

Under the background of energy strategy of"double carbon" target,the development of renewable energy such as wind and solar energy is inevitable.The intermittent and unstable characteristics of renewable energy sources bring great challenges to the safety and stability of power grids,and energy storage technology is an effective solution.Compared with other energy storage technologies,molten salt thermal storage technology has the advantages of large capacity,low cost and long life,and has been widely used in engineering.The experimental study of molten salt thermal storage is of great significance to the development of thermal storage technology.The actual melting and heating process involves the safety of the tank,which is one of the important issues of concern in molten salt thermal storage.In this paper,for the experimental system of molten salt test bench,the valves as well as temperature,flow and pressure measuring devices are planned and arranged.For the molten salt freeze plugging problem,the piping arrangement is designed and the slope of the piping is corrected,and the strategy of molten salt segmental purging is developed.For the problem of molten salt melting in the molten salt tank,a step heating strategy was developed.Through PLC programming,10 kW constant power heating experiments,40 kW constant power heating experiments and three step heating experiments were carried out,and the most suitable heating strategy was derived by comparison.The molten salt-air heat exchanger was designed as a shell and tube type with a maximum heat transfer of 6 kW,and the technical parameters of the heat exchanger were obtained through thermal calculations,and the pressure drops of the tube and shell processes were obtained through hydraulic calculations.Finally,a drawing of the heat exchanger was made using SolidWorks software.In this paper,the experimental system was planned and arranged to provide reliable and stable experimental conditions for subsequent research and insight into the engineering application of molten salt.The melting process of molten salt was optimized,the heating time was greatly reduced,and the heating rate was controlled to below 1.5℃/min,which is a reference for the design,construction and operation of molten salt experimental benches using similar heating methods.The technical design of the molten salt-air heat exchanger was carried out,laying the necessary foundation for the subsequent experimental study of heat transfer.