Embrittlement pretreatment of fibrous biomass for improving its grindability and combustibility in coal firing power generation

Co-firing fibrous biomass with coal is a low-carbon option, but poor grindability and uncertain combustion limit its use. A mild embrittlement pretreatment at 230 °C was applied to upgrade fibrous biomass for efficient co-firing. The selective degradation of hemicellulose and part of cellulose turned the dense fibrous matrix into a brittle, porous solid. The grindability index increased nearly fivefold, and the higher heating value increased from 17.1 to 20.1 MJ kg−1, while energy yield remained above 75%. With 20% embrittled biomass, co-firing improved the combustion of two bituminous coals, Shitan (SC) and Wangbu (WB). Ignition and burnout temperatures decreased by 44 °C and 29 °C for SC, and by 38 °C and 25 °C for WB. Combustion indices, including the comprehensive combustion performance index S, increased by up to 40.4% for SC. Kinetic analysis revealed that activation energy during char oxidation decreased by up to 40.3% for SC and 28.2% for WB, due to enhanced volatile release and porosity that promoted oxygen transfer. Ash fusion temperatures remained stable across blending ratios, indicating minimal slagging risk and good ash compatibility. Embrittlement pretreatment offers an energy-efficient, practical route to enable large-scale biomass integration into coal-fired systems for cleaner power generationp.