The Effect of Nickel Alloy Corrosion under Cathodic Protection inside High Temperature Molten Salt Systems

Abstract

One way to potentially reduce the costs of concentrated solar power (CSP) systems is to operate the central receiver at high temperatures which allow for more efficient thermodynamic power conversion cycles. Molten salts are one potential heat transfer fluid that can operate efficiently at these temperatures, but their use will introduce other technological challenges, such as corrosion reactions. Cathodic protection may mitigate corrosion of metal surfaces by shifting the potential of the alloy below its oxidation potential. The behavior of molten salt (CSP) systems under cathodic protection can be obtained by developing a 3-D model. A simplified model was designed for a thermosiphon vessel. This thermosiphon vessel exposed the alloy coupons to isothermal and non-isothermal conditions expected in concentrated solar power (CSP) plants. The model compared the corrosion rates for the cases with and without cathodic protection. Results were in good agreement with experimental values with less than 5% error.