Corrosion Mechanisms and Alloy Performance in Waste-to-Energy Boiler Combustion Environments

The combustion of municipal solid waste in a boiler for power generation produces a very corrosive environment for the boiler tube materials. The environment contains HCl, SO₂, various metal chlorides and sulfates along with typical combustion products. Due to their low melting points and high vapor pressures, metal chlorides are believed to be primarily responsible for the boiler tube corrosion problems encountered in waste-to-energy (WTE) boilers. Without some sort of corrosion protection method, the standard materials of the construction for the boiler, such as carbon and Cr-Mo steels, are subject to severe high temperature corrosion attack. The present paper discusses the possible modes of high temperature corrosion for waterwalls and boiler tubes in the convection section, and the prevailing protection method for these components as well as the performance of various alloys in these hostile combustion environments.