Experimental study of biomass combustion and separation using vertical cyclone combustor

The present work is devoted to study experimentally the effect of the vortex finder length to the cyclone height ratio (S/H), the air flow rate, and the biomass particles (diameters, feeding flow rates, and type) on the separation efficiency of the cyclone in cold tests. Results from the cold tests were taken as a base of the combustion tests in order to identify the optimum operating conditions. In addition, the combustion characteristics of the cyclone were studied. The experimental results showed that, by increasing the air flow rate, the biomass particles diameter and decreasing the biomass feeding flow rate, the separation efficiency increased. Also, by increasing the vortex finder length to the cyclone height ratio (S/H) the separation efficiency increased for vortex finder ratios greater than 8 % up to 16 % where the separation efficiency reached its maximum value. After that, the separation efficiency started to decrease by further increase of the vortex finder ratio. It is worth stating that, the fine biomass particles gave lower separation efficiency than the coarse particles at whole ranges of feeding flow rates. For all particles diameters, the maximum centerline axial temperatures were obtained at the top of the cyclone. For coarse particles diameters, the centerline axial temperature started to decrease until axial distance of y/D = 3. After that, the centerline axial temperature increased slightly until the exit of the cyclone. For fine particles diameters the centerline axial temperature decreased until the bottom of the cyclone. Finally, the combustion of LPG and biomass fuel mixture revealed higher values of radial temperatures than those obtained from the combustion of the LPG only at the same thermal load.