Effect of dynamic conditions on high-temperature corrosion of ternary carbonate salt for thermal energy storage applications

Abstract

Li2CO3–Na2CO3–K2CO3 salt is one of the candidates for 3rd generation concentrated solar power (CSP) plants, aiming to increase the operational temperature. This rise of temperature significantly increases the corrosion issue of molten salts. However, there is a lack of studies focused on the effect of salt flow on the corrosion kinetic for this ternary carbonate salt. In this work, corrosion experiments under static and dynamic conditions are compared for SS310 subjected to ternary carbonate salt at 600 °C. A complete characterization of the corrosion layer, surface and cross-section, was carried out by means of SEM-EDX and XRD, while the molten salts after the corrosion tests were analysed by ICP-OES and XPS. The dynamic experiment exhibited an enlarged spallation of the corrosion layer, leading to a thinner and less homogeneous scale. This feature exposed the chromium containing phase and considerably increased the extent of its dissolution into the salt. The obtained results remark that the detrimental effect of dynamic conditions on the corrosivity of molten carbonate salt cannot be neglected and must be taken into account in the design of 3rd generation CSP plants.