(97a) Measuring Jet Penetration in a 3D Bubbling Fluidized Bed

Fluidized beds are used in a variety of industrial processes including drying, combustion, and catalysis due to their high heat and mass transfer rates, uniform temperature distributions, and low pressure drops. The aeration region directly above the gas distributor of a fluidized bed is important because of the presence of jets issuing from individual inlet holes. These jets lead to high and irregular reaction rates in this region and may damage any nearby internal parts through a sandblasting effect. Therefore, accurate measurement of the jets within the aeration region is integral to the proper design of a fluidized bed.

Individual jets issuing from an aeration plate can be easily identified using 3D X-ray computed tomography (CT) imaging. This study presents a method to quantify jet length and jet expansion angle from each individual aeration jet identified in 3D X-ray CT images. Analysis has been completed using a 10.2 cm diameter bubbling fluidized bed operating over a range of superficial gas velocities. Glass beads, ground walnut shell, and ground corncob were the bed materials and covered a range of material densities. Each material had a particle size range of 500-600 microns and were identified as Geldart Type-B materials. In general, the penetration length and jet angle were independent of bed material. A maximum jet penetration occurred at a superficial gas velocity of two times the minimum fluidization velocity, and the jet expansion angle decreased as the superficial gas velocity increased.