K. Patil, T. Bowser, D. Bellmer, and R. Huhnke. “Fluidization Characteristics of Sand and Chopped Switchgrass-Sand Mixtures”. Agricultural Engineering International: the CIGR

A laboratory, fluidized-bed gasifier is being researched as a means to gasify feedstocks in a process to produce ethanol from biomass. Fluidization characteristics of the bed, especially minimum (Umf) and complete (Ucf) fluidization velocities, were measured because they are critical to the operation of the gasifier. Fluidization properties of sand and chopped switchgrasssand mixtures of different particle sizes and bulk densities were studied in this work. Experiments were performed in a 250-mm ID, fluidized-bed, clear plastic column that was dimensionally identical to the laboratory gasifier. The percentages of chopped switchgrass in the mixtures studied were 1.0, 2.0, 2.9, 4.8, 6.5 and 8.3% by weight. Sand particle sizes studied had geometric mean diameters (GMD) of 375, 381, 450, 621and 863 μm. The Umf and Ucf values were more sensitive to the sand particle size than to the percent switchgrass level in the switchgrass-sand mixtures. The Ucf/Umf ratio decreased with an increase in the percent weight of switchgrass. The descriptions of the behavior of the fluidized bed are also included in this study.