Fluidization of Biomass Particles in a Gas-Solid Fluidized Bed

Studies on the fluidization of biomass particles and binary mixtures of biomass particles with fluidization mediums were carried out. The biomass particles used were wood chip, mung beans, millet, corn stalk, and cotton stalk, and the fluidization mediums employed were silica sand, continental flood basalt (CFB) cinder, and aluminum oxide. Experiments were performed in a rectangular biomass fluidized bed (cross-sections of 0.4 x 0.4 in in a dense region and 0.5 x 0.5 in in a freeboard region, with a height of 4.4 m). The minimum fluidization velocity (UMF) of approximate sphere biomass particles (wood chip, mung beans, and millet) and long thin biomass particles (corn stalk and cotton stalk) in different transection diameters and ratios of length/diameter were tested. Furthermore, the UMF of binary mixtures of biomass particles with fluidization mediums of different particle densities and diameters was obtained. The results showed that the UMF of long thin biomass increases with an increasing transection diameter and aspect ratio of length/diameter, while long thin biomass with the aspect ratio over a certain value could not be fluidized; the UMF of binary mixtures increase with an increasing density and diameter of fluidization medium and an increasing mass fraction of biomass. On the basis of experimental data, new correlations were developed for predicting the values of UMF. Comparisons of the predicted UMF by the correlations with experimental data in both the present work and literature were carried out. It was found that the present proposed correlations reasonably well-predicted the UMF of biomass particles and binary mixtures of biomasses with fluidization mediums.