In this work, the ash fusibility behaviour of selected agricultural residues and their blends with lignite was studied, by carrying out chemical, mineralogical, fusibility and thermogravimetric analyses and calculating slagging/fouling indicators for predicting deposition tendencies in boilers. Two additives, bauxite, and clinochlore, were used at varying amounts to reduce ash melting, followed by examining their anti-fusion mechanisms. Initial deformation and softening temperatures of biomass materials were low for combustion processes operating above 900 °C due to their high concentration in K, Na, and P compounds. When the additives were mixed with raw fuels or lignite/biomass blends, the initial deformation of ashes started at temperatures up to 340 °C higher, whereas the fluid temperature in most cases exceeded 1500 °C. Bauxite was more effective than clinochlore. The positive impact of additives was attributed to the mineralogical transformations during ashing to phases with a high melting point through reactions with K, Na-bearing minerals, or CaO of fuel ashes.
Effect of Mineral Additives on Fusion Behavior of Agricultural Residue Ashes during Combustion or Co-combustion with Lignite
