Effects of molten-salt LiNO3 on high-temperature corrosion behaviour of absorption tubes of a concentrating solar power system

Abstract

ABSTRACTThe main aim of the present research was to investigate the effects of a ternary nitrate salt (NaNO3–KNO3–LiNO3) on high-temperature corrosion behaviour of stainless steel 321 (SS 321) in a parabolic trough collector in a concentrating solar power system. The corrosion behaviour of SS − 321 was examined in a ternary salt (LiNO3 (25 wt-%)-NaNO3 (25 wt-%)-KNO3 (50 wt-%)) at 400°C and 550°C for 250 h, 500 h and 1000 h, and the obtained findings were then compared with the results of a solar salt ((NaNO3 (60 wt-%)-KNO3 (40 wt-%)). In order to determine the quantitative corrosion behaviour of SS − 321, the results of immersion tests and microstructural investigations obtained through scanning electron microscopy and energy-dispersive X-ray microanalysis were also considered. It was found that the addition of lithium nitrate (LiNO3) to solar salt formed resistant oxide layers on the surface of SS 321 and subsequently, increased its corrosion resistance ability.