Comparison of the Combustion Characteristics of Rice Husk, Sawdust, and Groundnut Shells in a Bubbling Fluidized Bed

Agricultural residues, such as rice husk, sawdust, wood waste, groundnut shells, etc., could play an important role as energy sources. These biomass fuels are difficult to handle due to high moisture and fines content and also due to fuel ash softening at relatively low temperatures. Fluidized bed energy technology offers several unique characteristics for using biomass in small-scale energy conversion operations. In the present work, combustion studies of rice husk, sawdust, and groundnut shells were conducted in an atmospheric bubbling fluidized bed in high excess air environment and observed considerable reduction in CO levels in flue gases and unburned carbon in residual ash. The combustion efficiency, temperature distribution in the reactor, ash characteristics, etc. are also studied in a fluidized bed at various operating conditions. Secondary air is introduced in the enlarged free board to provide high turbulence for flue gases and unburned particles in the reactor vessel.