Fireside Corrosion in Coal- and Oil-Fired Boilers

The presence of certain impurities in coal and oil is responsible for the majority of fireside corrosion experienced in utility boilers. In coal, the primary impurities are sulfur, alkali metals, and chlorine. The most detrimental impurities in fuel oil are vanadium, sodium, sulfur, and chlorine. This article describes the two categories of fireside corrosion based on location in the furnace: waterwall corrosion in the lower furnace and fuel ash corrosion of superheaters and reheaters in the upper furnace. It discusses prevention methods, including changes to operating parameters and application of protective cladding or coatings.