The role of chlorine in high temperature corrosion in waste-to-energy plants

High temperature corrosion has been a serious problem in municipal solid waste (MSW) incinerators since the emergence of waste-to-energy (WTE) plants in the 1960s. Early researchers conjectured that corrosion was caused by sulfur compounds, but it soon became evident that the dominant corrosive species are chlorides, typically in combination with alkali metals (Na, K) and heavy metals (Ph, Zn). Yet, many uncertainties remain with respect to the complex interactions between metallic materials of construction and their corrosion products with aggressive species in the combustion atmosphere and in fireside deposits. Following a review of historical background, MSW incineration technology and refuse boiler materials/corrosion, this paper will examine the causes and mechanisms of high temperature corrosion in WTE plants, as well as the environmental and alloy-related factors affecting metal wastage. Attention will be called to remaining uncertainties regarding corrosion mechanisms, and to apparent incongruities and conflicting data on materials performance to help identify areas for further R&D.