Design and commissioning of the worldwide first nitrate molten salt test rig for component testing at 620°C

Kurzfassung

Energy storage is crucial for the on-demand generation of electricity from renewable sources like wind and photovoltaics. Thermal energy storage can be particularly useful, especially when repurposing existing fossil-fired power plants, as it provides a cost-effective solution for implementing large-scale grid energy storage (Trieb et al., 2022). State-of-the-art molten salt storage systems operate at a maximum temperature of 565°C (Mehos et al., 2020). However, utilities aim for a higher temperature of at least 620°C to accommodate supercritical steam cycles. These higher temperatures are crucial to obtain maximum efficiencies. Research has shown that this temperature increase is generally feasible from a material compatibility perspective (Bonk et al., 2020). So far, there are no commercial components, such as pumps, valves, and instrumentation, available 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 hydraulic pre-tests demonstrated the general operability of all components with water before hot commissioning with molten salt at 620°C.