Modeling and Analysis of Stress in High Temperature Molten Salt Trough Receivers

SkyFuel has investigated the stresses and deformations occurring in parabolic trough receivers operating at temperatures above 425 °C. Operating at these temperatures allows for direct molten salt storage and higher efficiency conversion from thermal to electric energy. However, at these temperatures, the typical stainless steels used in receiver construction are susceptible to chromium carbide precipitation. After the precipitation has occurred, the steel is vulnerable to intergranular corrosion, and the fatigue strength of the steel is reduced. Corrosion increases the stresses in the receiver walls, and the reduced fatigue strength lowers the stress limit where failure will occur. This paper presents the results of an analysis of these stresses and an evaluation of the receiver material at these operating temperatures. It is shown that parabolic trough receivers can be designed to mitigate the negative effects of chromium carbide precipitation and operate above 425 °C without risk of premature failure.