(65f) Oxidizing Properties of « Solar Salt »

Solar Salt is a name sometimes given to a molten salt mixture made up of about 60% of sodium nitrate (NaNO3) and 40% of potassium nitrate (KNO3). This composition is near the eutectic point and is thermally stable until 600°C. It is popular in Industrial Solar Energy Projects and is used for storing energy in the form of heat to smooth out the peaks in electricity production. However for some technologies, combustible substances, like a thermal fluid for example, may come into contact with the molten salt. The aim of the paper is then to study the oxidizing properties of the solar salt in order to estimate the energy released by a potential reaction between the salt and combustibles and estimate safety issues. In that purpose, four types of experiments were carried out: the standard UN O.1 test for solid oxidizers, the standard UN O.2 test for liquid oxidizers, differential scanning calorimetry (DSC) and isothermal calorimetry (C80). The experimental program demonstrates the oxidizing properties of the solar salt and shows that the reactivity of solar salt with other combustibles has to be taken into account in a global risk analysis of a Solar Energy Central.