Understanding the jetting phenomena near the gas distributor plate in a fluidized bed is important to gas–solid mixing, heat and mass transfer, and erosion to any bed internals, which can all affect the performance of the bed. Moreover, acoustic vibration in a fluidized bed can be used to enhance the fluidization quality of the particulate matter and influence the jetting behavior. Characterizing the jetting structure using X-ray computed tomography (CT) in a three-dimensional (3D) fluidized bed, with and without acoustic intervention, is the focus of this study. A 10.2 cm ID fluidized bed filled with glass beads and ground walnut shell, with material densities of 2500 kg/m3 and 1440 kg/m3, respectively, and particle sizes ranging between 212 and 600 μm, is used in these experiments. X-ray CT imaging is used to determine local time-average gas holdup. From this information, qualitative and quantitative characteristics of the hydrodynamic structure of the multiphase flow system are determined. Local time-average gas holdup images of the fluidized bed under acoustic intervention at a high superficial gas velocity show that jets produced near the aeration plate merge with other jets at a higher axial position of the bed compared to the no acoustic condition. Acoustic fluidized beds also have a fewer number of active jets than the no acoustic fluidized bed, which allowed for a more homogeneous gas holdup region deep in the bed. Hence, the acoustic presence has a significant effect on the jetting phenomena near the aeration plate in a fluidized bed.
Characterizing Jetting in an Acoustic Fluidized Bed Using X-Ray Computed Tomography
Contributed by the Fluids Engineering Division of ASME for publication in the JOURNAL OF FLUIDS ENGINEERING. Manuscript received November 17, 2014; final manuscript received August 17, 2015; published online December 8, 2015. Assoc. Editor: E. E. Michaelides.
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Escudero, D. R., and Heindel, T. J. (December 8, 2015). "Characterizing Jetting in an Acoustic Fluidized Bed Using X-Ray Computed Tomography." ASME. J. Fluids Eng. April 2016; 138(4): 041309. https://doi.org/10.1115/1.4031681
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