New Problems of Boiler Corrosion after Coupling Combustion of Coal and Biomass and Anti-Corrosion Technologies

Abstract

This study explores the corrosion issues arising from the coupled combustion of coal and biomass and proposes potential solutions. Biomass, as a renewable energy source, offers advantages in energy-saving and carbon reduction. However, the corrosive effects of alkali metal compounds, sulfur (S) and chlorine (Cl) elements in the ash after combustion cannot be underestimated due to the high volatile content of biomass fuels. We investigate the corrosion mechanisms, as well as the transfer of Cl and alkali metal elements during this process. Comparative corrosion analyses are conducted among coal-fired boilers, pure biomass boilers and boilers with coupled combustion. Various biomass types in co-firing are studied to understand different corrosion outcomes. The main factors influencing corrosion include the physicochemical properties of biomass feedstock, furnace temperature and heating surface materials, with the chemical composition and ash content of biomass playing a dominant role. Currently, the methods used for anti-corrosion include water washing pretreatment of biomass feedstock, application of novel alloys and coatings and the development of additives to inhibit fouling, ash deposition and corrosion. Efficient inhibitors are economical and easy to produce. Additionally, biomass can be converted into biomass gasification gas, although challenges related to tar still need to be addressed.