Impurity Influence in Physico-chemical and Corrosion Properties of Chilean Solar Nitrates

Abstract

SERC-Chile has been created as a center of excellence in solar energy research. The center will aim to be a world leader in basic research on solar energy technology and applications, with a particular emphasis in developing the potential of Chile's Atacama Desert, one of the world's prime locations for the study and application of solar power. Typical impurities present in Chilean nitrates are Mg, SO4 and Cl, among others.In the present research a full characterization of the binary solar salt has been carried out, studying the influence of the most important impurities in the thermal process as well as the corrosion ability at the storage temperatures of the main important solar thermal plants.The performed thermal analysis are been run by Differential Scanning Calorimeter (DSC), Modulated Differential Scanning Calorimeter (MDSC) and Thermogravimetric Analize (TGA), leading phase transitions, melting point, heat capacities and thermal stability values of tested salts. The moisture will be another parameter to check in this technology showing an improvement in mixtures with a heat treatment before the corrosion test.The corrosion scope were determined by gravimetric tests, measuring the weight gain of three alloy steels with low Cr content at 390°C during 2000h, identifying the corrosion products via scanning electron microscopy (SEM) and x-ray diffraction (XRD). Fe2O3 and Fe3O4 were the most important corrosion products found, being observed also the formation of some stable compounds with the impurities of the salt, as magnesiumferrite (MgFe2O4).