Dynamic corrosion testing of metals in solar salt for concentrated solar power

F. Sutter, C. Oskay, M.C. Galetz, T. Diamantino, F. Pedrosa, I. Figueira, S. Glumm, A. Bonk, A. Agüero, S. Rodríguez, T..J. Reche-Navarro, S. Caron

Solar Energy Materials and Solar Cells 232 (2021), 111331, DOI: j.solmat.2021.111331

sutter2021_fig3

Left) Schematic of flow diagram of test bench for molten salt components. Right) Test loop for components. The 3 m long sample holder has been placed inside the pipe section close to the inlet.
Reprinted from Solar Energy Materials and Solar Cells, Copyright (2021), with permission from Elsevier.

sutter2021_fig4

a) samples mounted in sample holder before testing. b), c) and d) detailed view of sample holder inserted in DN50/PN40 pipe.
Reprinted from Solar Energy Materials and Solar Cells, Copyright (2021), with permission from Elsevier.

Potassium nitrate and sodium nitrate in mixing proportion of KNO3–NaNO3 40-60 wt% (also called solar salt) has been successfully used for over a decade as heat storage medium for concentrated solar power parabolic-trough collector plants at temperatures up to 400 °C. At temperatures of 560 °C, reached in state-of-the-art solar tower systems, corrosion of metallic components in contact with solar salt can become an issue and has caused leaks and plant shut-downs in recently built tower projects. While the corrosion rates of several materials have been determined for different temperatures in static molten salt immersion experiments, there is a lack of corrosion data for dynamic in-service conditions. In this work, a dynamic corrosion test has been conducted on 19 different material types including protective coatings, mimicking flow-rate, temperature gradient and draining of in-service operation of a receiver in a concentrated solar power tower. The measured corrosion rates are presented and compared to static corrosion tests reported in literature.

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https://authors.elsevier.com/a/1divz3In-99sNJ

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