Study on the effect of solar salt thermal decomposition reaction on internal and external characteristics of molten salt pump

Solar salt is the main heat storage medium for concentrated solar power plants. It will undergo thermal decomposition reactions to produce gas when the temperature is higher than 450°C. So that the thermal decomposition bubbles of solar salt are free in the molten salt pump flow channel, which have serious impacts on the internal and external characteristics of the molten salt pump. This paper takes the 16ENH-2 high-temperature molten salt pump as the research object. Based on the thermal decomposition mechanism of solar salt, we studied the influence of different thermal decomposition gas generation rates and different flow rates on the bubble coalescence and breakage phenomenon in the flow channel, and the influence mechanism on the internal and external characteristics of the molten salt pump. The research results show that the thermal decomposition gas generation rate is the key factor affecting the gas content in the first stage impeller and the bubble size distribution in the second stage impeller. The flow rate is the key factor affecting the gas phase distribution position in the first/second stage impeller and the bubble size distribution in the first stage impeller. The bubble coalescence within the first stage impeller is the main reason for the pump performance degradation. The research results can provide theoretical guidance for the efficient and stable operation of the molten salt pump.