Fluidized beds slug properties

Flow properties. Slugging tendency of a fluidized bed increases with increased Stormer viscosity (207). The modified Stormer viscometer used ill this work is provided with a paddle that is rotated in the fluidized bed (by means of a weight attached to a string passing over a system of pulleys). Viscosity is measured by determining the weight required to spin the paddle at 200 r.p.m. Stormer viscosity of the bed increases with decreased gas velocity and with increased size and density of particles. Viscosity of coarse catalyst is decreased, within limits, by addition of fines. 

Important characteristics of Mode I of operation closely relate to the bubble flow patterns which are coalesced bubble flow, dispersed bubble flow, slug flow, and transitional flow. The exact definition of these regimes is rather subjective and is frequently the result of visual observations. These flow patterns determine many of the properties of cocurrent three phase fluidized beds such as porosity, bubble characteristics, mixing, heat and mass transfer. The specific values of these properties, their changes and their interdependence with respect to the flow patterns is covered in the following sections of this review. 

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