This paper examines the nature of coal ash flue gas corrosion and factors influencing its degree of aggressiveness. Citing both laboratory and plant experience, the performance of a number of nickel containing alloys are assessed as to their general performance limits based on corrosion resistance. The role of certain key alloying elements is addressed. Corrosion behavior is examined in terms of chromium content of the alloy, the SO2/SO3 content of the flue gas, the alkali content of the coal ash and the surface temperature of the alloy exposed to the environment.
Keywords: coal ash corrosion, oxidation, sulfidation, alkali sulfates, laboratory testing, field exposure, alloying elements, ferritic steels, austenitic stainless steels, nickel alloys