High-temperature corrosion behavior of S30432 in high-efficiency ultra-supercritical boiler burning low-alkali and high-sulfur coal

In this study, the resistance of S30432 to low-alkali coal ash corrosion in a high-efficiency USC boiler was investigated. Currently, S30432 is widely used in the high-temperature superheater and reheater of boilers burning low-alkali and high-sulfur coal. During the experiment, S30432 coated with low-alkali coal ash were fixed in a high-temperature tubular reactor, and hot gas at 650 °C and 700 °C containing SO2 passed over the specimens for 2000 h. Then the specimens were tested by X-ray diffraction, scanning electron microscopy, and energy-dispersive spectroscopy. It was found that S30432 specimens mainly underwent high-temperature oxidation. For the gas temperature of 700 °C and SO2 volume concentration of 0.35 %, the sulfidation reaction occurred and the weight change was only 1.08 mg cm-2. The results show that there is no obvious high-temperature corrosion after three years of operation of a 700 MW 620 °C boiler. The results are in contrast with the high-alkali coal ash corrosion resistance of S30432. It is concluded that S30432 can meet the requirements of a high-efficiency USC boiler burning low-alkali and high-sulfur coal.