Performance Evaluation of Molten Nitrate Salt Components at 620°C - Insights from Commissioning and Experimental Trials

Abstract

Energy storage is crucial for the on-demand generation of electricity from intermitted renewable sources like CSP. Most solar thermal power plants use thermal energy storage, typically at 565°C, but increasing to 620°C could enhance efficiency with supercritical steam cycles. Research indicates feasibility from a material standpoint [1]. However, there are currently no commercial components such as pumps, valves and instrumentation on the market for 620°C nitrate salt. For this purpose, a test rig for up to 400 kg nitrate molten salt was developed and built at DLR. The aim of the experiments is to demonstrate the functionality of pump and valve prototypes as well as measurement equipment at a temperature of 620°C. First pre-tests with water and tests with molten salt at 620°C demonstrated the general operability of all components. Hot commissioning successfully took place in March 2024.