Investigation of fireside corrosion at water-cooled wall from a coal-fired power plant in China

•High temperature corrosion on water-cooled wall of a power plant was well studied.•Corrosions present as layered structures with different micro-morphologies.•Sulfur and iron are the major elements components in the corrosion products.•A sulfide type corrosion at water-cooled wall occurred in the power plant studied. Corrosion products from water-cooled wall of a coal-fired power plant in China were finely collected and further split into samples of different layers along their growth direction. The physicochemical properties of all the samples were well characterized for understanding the mechanisms of high temperature corrosion. The results showed that sulfide type corrosion occurred at the water-cooled wall in the coal-fired power plant. Corrosion products were layered structures. The samples of the outer layer showed loose and porous structures, while the samples of the inner layer were dense structures. The major elemental components of the corrosion products of different layers were sulfur (S) and iron (Fe). The distribution of both S and Fe in the samples of different layers were varied, showing a decreasing trend in the samples from the inner layer to the outer layer. Iron sulfide and magnetite were the major mineral components of the corrosion products, and the content of the iron sulfide decreased in the samples from the inner layer to the outer layer. However, some alumina-silicate from the fly ash generated from the coal combustion was also found attached to the intermediate and outer layers of the corrosion products.