HYDRODYNAMIC STUDIES OF RICE HUSK SAW DUST AND GROUND NUT SHELL FUELS IN A FLUIDIZED BED

Biomass is a low-grade energy source and must be upgraded for effective utilization of biomass residue as fuels. In general, biomass comprise of non-uniform particles of variety shape and size peculiarly in large density variation. A Fluidized bed technology converts the biomass into useful energy. Computational Fluid Dynamics simulations are carried for cylindrical bubbling fluidized bed gasification chamber of following specifications, static bed height 1m with 0.150m diameter. In the present work, three types of 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 for five different levels of fluidization velocities, (0.86m/s, 1.01 m/s, 1.13m/s, and 1.31m/s). Sand with density 2600kg/m3 and with a constant particle diameter of sand 400μm is employed for all the simulations. Simulations are conducted using commercial Computational Fluid Dynamics software, ANSYSFLUENT. It has been observed that, for enabling good mixing and uniform distribution of biomass fuel with bed material, bubbling character is increased with increase in inlet air velocities followed by asymmetrical fluctuations of volume fractions in radial directions at different bed heights levels