Causes Analysis of High-temperature Corrosion of Station Boiler Water Walls
The causes of high temperature corrosion of water wall was investigated by means of macro analysis,microstructure observation,scanning electron microscopy,energy spectrum composition analysis,and X-ray.Results showed that due to the use of tangential firing at four corners in the boiler,local high temperatures in the water-cooled wall were observed;the composite air classification low NOx combustion sys-tem causes some burner areas to be in a reducing atmosphere with low oxygen concentration,resulting in excessively high CO+H2S concentra-tion in the flue gas;the sulfur content of the coal fed into the boiler exceeds the design value significantly,resulting in the formation of high concentrations of H2 S and SO2;the corrosion of the water-cooled wall towards the fire side is mainly caused by sulfur corrosion.In summary,the following suggestions are given:the sulfur content of the incoming coal is controlled to reduce the sulfur element content in the coal,in or-der to reduce the concentration of H2S and SO2;Optimize and adjust combustion by using side air technology to introduce air into the furnace,reduce the reducing atmosphere concentration in the high-temperature corrosion area of the water wall,and increase local oxygen content;In ar-eas with severe high-temperature corrosion,spray coating treatment is applied to the water-cooled wall pipes to enhance their high-temperature corrosion resistance.
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维普
