(445a) Jetting Characterization in an Acoustic Fluidized Bed Using X-Ray Computed Tomography

The mixing and jetting phenomena that occurs above the distributor plate is of extreme importance to the overall performance of a fluidized bed. A poor distribution between the fluidizing media and the solid particulate can produce low heat transfer rates and cause sintering and defluidization of the particulate matter. Obtaining qualitative and quantitative information of these phenomena will increase the understanding of the hydrodynamic structure in fluidized beds. This study uses X-ray computed tomography imaging to characterize the jetting above a multi-hole distributor plate in a fluidized bed with and without acoustic vibration. A cold flow 10.2 cm ID fluidized bed filled with glass beads and ground walnut shell, with densities of 2500 kg/m³ and 1400 kg/m³, respectively, and particle size ranges between 212-600 µm, are used in these experiments. Local time average gas holdup information obtained using X-ray computed tomography is used to determine qualitative and quantitative characteristics of the jetting structure above the distributor plate. Under the influence of acoustic vibrations, the jets extend deeper into the bed, producing merged jets at higher axial locations in the fluidized bed. Furthermore, the presence of acoustic sound vibrations allows larger bubbles to break into smaller ones, increasing the jet momentum, which allows the jets to have a higher average jet length compared with the fluidized bed without acoustic vibrations. The addition of acoustic vibrations also produced an increase in the jet expansion angle. Thus, the jetting structure is altered due to the presence of acoustic vibrations in a 3D fluidized bed, which ultimately produces a better and more homogenous material distribution inside the fluidized bed.