A review of biomass ash related problems: Mechanism, solution, and outlook

The smooth combustion process of biomass is of great importance as the world transit away from the use of fossil fuels to embracing environmentally friendly and renewable energy. Ash-related problems, such as slagging, fouling, agglomeration, and corrosion, significantly disrupt the efficient operation of gasification systems, leading to unforeseen breakdowns. Potassium, a prevalent alkali metal in biomass, reacts with chlorine and sulfur in flue gas, generating troublesome compounds. This interaction constitutes the primary source of challenges linked to biomass combustion processes. Additives, especially kaolin, an aluminum-silicate, proved most effective in capturing potassium during combustion, forming high-melting-point potassium aluminum silicate compounds. Hence, this paper provides a summary of issues related to biomass ash, explores the deposition mechanism, outlines methods to mitigate problems associated with ash, and concludes by introducing alum sludge as an outlook.