Characterization and Production of Solid Biofuel from Sugarcane Bagasse by Hydrothermal Carbonization

Hydrothermal carbonization of sugarcane bagasse using hot-compressed-water was investigated for the treatment of solid material to understand the occurring decomposition reactions. The experiments were performed in 14 ml of batch type reactor in the range of temperatures 200–300 °C and reaction times 3–30 min. After separation of solid residues from liquid material, approximately 34–88 wt% of raw material was recovered as solid products. Characterizations show that increased treatment temperature and reaction time causes structural changes of the sugarcane bagasse. When the temperature and reaction time was increased, hemicellulose and cellulose gradually dissolved, leaving a lignin-like acid insoluble residue. The presence of the residue increases the fixed carbon and decreases the volatile matter content of the solid product. Dehydration significantly decreases the oxygen content and slightly decreases the hydrogen content of the treated material. With these changes, the caloric value and of the solid product increases by 1.1–1.9 times that of the raw material. Higher temperature treatment (300 °C) produces a material with high caloric value and fixed carbon, with a composition comparable to typical solid fuels such as lignite (or low rank-coal). The hydrothermal carbonization of sugarcane bagasse could be a solution to reduce environmental pollution caused by the combustion of wet stockpiled sugarcane bagasse in the sugar industry. The treated sugarcane bagasse reduces energy loss, smoke and water vapor during the combustion process.