Abstract:

In order to solve the frequently occurred leakage problem of super heater in the actual production process of refuse incinerator, this paper conducted a comprehensive analysis of the corroded tube of a certain refuse incineration power plant using the scanning electron microscope with energy disperse spectroscopy (SEMEDS), ion chromatograph (IC), Xray fluorescence (XRF) and Xray diffraction (XRD), discussed its corrosion mechanism, and proposed some suggestions on how to prevent the corrosion leakage of super heater. The study shows that gaseous chlorine corrosion and alkali metal ash deposit corrosion are the root causes of corrosion leakage of super heater tubes. For gaseous chlorine corrosion, the HCl and Cl2 produced by refuse incineration could spread to the metal lining of tube wall and corrode it under oxidizing atmosphere, and together with the SO2 in flue gas, the synergistic effect would accelerate the corrosion and form some corrosion pits, which may lead to a leakage eventually. For alkali metal ash deposit corrosion, the alkali metal compound produced by refuse incineration deposits at the outside of tube wall, and the SO2 in flue gas could react with alkali metal compounds to form alkali metal sulfates, which could corrode the tube wall under oxidizing atmosphere. Besides, part of the alkali metal chlorides in ash deposition could corrode the ferruginous oxide film under oxidizing atmosphere, which also could accelerate the corrosion of tube wall.

Key words:

refuse incinerator, super heater tube, corrosion mechanism, leakage