Single pellet combustion studies of biomass and its blends for bioenergy

• Pellets were made from bagasse-saw dust and rice husk-saw dust blends • The pellets possessed optimum calorific value, high density, crushing and impact resistance • Burning rate in flaming and char oxidation zones, and CO 2 , CO emissions were assessed • Addition of saw dust to bagasse improved the mass burn rate and reduced CO emission • Addition of saw dust to rice husk kept the slagging and fouling at low levels This study evaluates the combustion characteristics of pellets of rice husk (RH), sugarcane bagasse (BG) and saw dust (SD), and the binary blends of RH-SD, and BG-SD. The pellets were thoroughly characterized for its moisture content, calorific value, pellet density, impact resistance and crushing resistance, and combusted in a lab scale set-up in open air environment under normal gravity. The mass loss, CO and CO 2 emission, and ash composition of the burnt pellets were measured, and the variations in mass burning rate and CO production are discussed. The mass burning rate in the flaming and char oxidation regimes, and total CO production were evaluated under a constant heat release from the pellets. RH pellet demonstrated the highest mass burning rate and the lowest CO emission, while the burning and emission characteristics of BG pellets improved with the addition of SD. The overall average burning rate increased by 68% for BG-SD and decreased by 36% for RH-SD blends with the addition of 30% SD. The total amount of CO produced per unit mass of fuel burnt was much lower for RH (4%) as compared to BG (13.97%) and SD (8.95%). A significant decrease in CO production was observed when 30% SD is added to BG. A correlation is proposed for calculating the mass burning rate of composite biomass pellets. BG and BG-SD pellets exhibited higher slagging and fouling tendency due to higher alkali content in their ash while, RH and RH-SD pellets exhibited lower slagging and fouling tendency, primarily due to high silica.