Effect of complex municipal solid waste incineration flue gas on the corrosion of various alloys at 550 °C

Abstract

To investigate the corrosion characteristics of the typical complex municipal solid waste incineration flue gas environment, this study examined the high-temperature corrosion behavior of three alloy types: 12Cr1MoV, TP347H, and Inconel 625. The alloys were exposed to a multi-factor coupled corrosion environment of 7 % O2, 600 ppm HCl, 100 ppm SO2, N2, and a deposited mixed salt of NaCl/50 wt% K2SO4. Visual inspection, corrosion kinetics, XRD, and SEM/EDS were adopted to compare the corrosion behavior of the alloys. The results revealed the highly corrosive nature of the environment, especially due to the presence of molten salts formed by the mixed alkali salts, which strongly accelerated the corrosion of the alloys. Severe failure behavior was observed in both the low-alloy steel, 12Cr1MoV, and the nickel-based alloy, Inconel 625. The 12Cr1MoV steel showed a dramatic mass gain, and the Inconel 625 alloy developed very loose and non-protective oxide scales. In contrast, the austenitic stainless steel, TP347H, exhibited the best performance, adhering to a parabolic corrosion kinetics model and forming a double layer of protective oxide scales. The combined effect of “active oxidation” and “electrochemistry” was identified as the dominant corrosion mechanism in this corrosive environment. Comparing the variations in corrosion behavior among the three alloys, it can be concluded that the formation of multi-layer oxide scales is crucial for effective corrosion protection. Furthermore, the composition of the additive elements and their proportions in the alloy play a significant role in determining the protective properties of these oxide scales.