Mean and Turbulent Particle Velocity in the Fully Developed Region of a Three-Phase Fluidized Bed

Abstract

A thorough experimental description of the time-averaged solids flow in the fully developed region of a cylindrical gas-liquidsolid fluidized bed was provided by using a noninvasive radioactive particle tracking technique (RPT). The 3-D local instantaneous velocity components (radial, axial, azimuthal) of a single radioactive solid tracer, having properties identical to those of the solids in the bed, were measured noninvasively over extended time periods to establish the radial distributions in the fully developed region of axial and radial particle mean and turbulent velocities, shear stress, and axial and radial eddy diffusion coefficients. Glass beads and polyvinyl chloride particles of various shapes and sizes were water-fluidized singly or as binary mixtures in a 100 mm ID Plexiglas column over air and water superficial velocity ranges that spanned the dispersed bubble, coalesced bubble, and transitional flow regimes.

Electrical Capacitance Tomography − A Perspective

“…Such applications include riser flows, particle coating and blending, drying, polymerization, and Fischer−Tropsch synthesis. , Nonintrusive techniques are used for tracking particle movement, and/or mapping instantaneous or time-averaged, local or cross-sectional averaged, phase hold-ups, and phase velocities. These techniques include particle image velocimetry, − laser Doppler anemometry, − phase Doppler anemometry, − positron emission tomography − , and radioactive particle tracking, − ultrasonic tomography, − nuclear magnetic resonance imaging (NMR or MRI), − and electrical impedance (resistive or capacitive) tomography. − …”

“…1,2 Nonintrusive techniques are used for tracking particle movement, and/or mapping instantaneous or time-averaged, local or cross-sectional averaged, phase hold-ups, and phase velocities. These techniques include particle image velocimetry, [3][4][5] laser Doppler anemometry, [6][7][8][9] phase Doppler anemometry, [10][11] positron emission tomography 12-15, and radioactive particle tracking, [16][17][18][19][20][21][22][23] ultrasonic tomography, [24][25][26] nuclear magnetic resonance imaging (NMR or MRI), [27][28][29][30][31][32] and electrical impedance (resistive or capacitive) tomography. [33][34][35][36][37][38] The inherently complex nature of multiphase flows requires a multidimensional measurement technique capable of providing real time monitoring of the process dynamics and physical properties.…”

Numerical simulations of gas–liquid–particle three-phase flows using a hybrid method

“…The mean particle velocities in the vertical and horizontal directions were compared quantitatively with the experimental data [13]. Referring to the experimental setting, Figures 12 and 13 depict these variables at a bed height of 0.2 m, where r indicates the radial distance from the particle position to the column center, and R is the column diameter.…”

“…As a validation procedure, the developed method was applied to two typical gas-liquid-particle mixture flows, which are a dam break with solid particles [12] and a three-phase fluidized bed [13]. The simulation results were compared with corresponding experimental data available in the literature.…”

“…In the fluidized bed experiment [13], three-phase fluidization was observed in a cylindrical Plexiglas column of diameter 0.1 m and height 1.5 m. The air and water were charged concurrently and uniformly from the column bottom. The solid particles used in the experiment were glass beads, whose physical parameters are listed in Table 3.…”