Cold Flow Studies of Rice Husk, Saw Dust, and Groundnut Shell Fuels in a Fluidized Bed

Abstract

Biomass is a low-grade energy source and must be upgraded for effective utilization of these residues as fuels. A fluidized bed technology permits a wide range of low-grade fuels of non-uniform size to be efficiently converted to other energy forms. Due to large density variations of fuel and inert solids in the bed, it is difficult to estimate hydrodynamic and mixing characteristics of the mixture in the bed. In the present work, three biomass fuels (i.e., rice husk, saw dust, and groundnut shells) are selected and their fluidization characteristics are estimated in the presence of sand bed. It is observed that, for good mixing and uniform distribution of biomass fuel with bed material, size of the sand particles plays a vital role and is found that the sand particles of mean diameter 0.66 mm for groundnut shells and sand particle size 0.44 mm for the other two fuels is best suited. The minimum fluidization velocity has been obtained from the experiential investigation for a fuel/sand two-component system and has been compared with the theoretical correlations available in the literature. A suitable correlation to determine the minimum fluidization velocity for the selected biomass fuels and sand mixture has been suggested.