Corrosion Monitoring and Control in Molten Chloride Based Concentrated Solar Power Systems

Abstract

Molten mixtures of MgCl2-KCl-NaCl are promising heat transfer fluid (HTF) candidates for the next generation concentrated solar power systems (Gen3 CSP), because of their low cost, high decomposition temperature, and favorable heat transfer characteristics. However, if not properly controlled, molten chloride salts can cause the corrosion of high-temperature metal alloys, such as Inconel, in CSP systems. Here we demonstrate an automated corrosion monitoring and control system that can be used to maintain the health of the structural alloys over long durations. The monitoring system includes a multifunctional voltammetry sensor that is able to measure the redox potential of molten MgCl2-KCl-NaCl mixtures as well as the presence of corrosion products. The sensor is capable of detecting corrosion products, such as Cr2+ and Fe2+, quantitatively at low concentrations (less than 100 ppm) with less than 2% error. The corrosion control capability is facilitated by the in-situ electrolytic production of Mg metal that is automatically initiated when the sensor indicates salt conditions favorable to corrosion. The results show that the corrosion is effectively mitigated when the salt potential is maintained to be sufficiently cathodic.The submitted abstract has been created by UChicago Argonne, LLC, Operator of Argonne National Laboratory (“Argonne”). Argonne, a U.S. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357. The U.S. Government retains for itself, and others acting on its behalf, a paid-up nonexclusive, irrevocable worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the Government. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan. http://energy.gov/downloads/doe-public-access-plan