Date of Award

Spring 1984

Document Type

Dissertation

Degree Name

Doctor of Engineering Science in Chemical Engineering

Department

Chemical Engineering and Chemistry

First Advisor

Angelo J. Perna

Second Advisor

Ching-Rong Huang

Third Advisor

Gordon Lewandowski

Fourth Advisor

Jacob Klapper

Fifth Advisor

Wing T. Wong

Abstract

A novel optical probe has been developed and used for on-line monitoring of the bubble characteristics in a three-dimensional gas fluidized bed. The probe sensor has a major dimension of 1.8 cm, and contains an LED and a photo-cell separated by a gap of 2.5 mm. Coupled with a non-inverting comparator circuit with hysteresis as a noise filter, the probe has been very effective in characterizing the size distribution, shape and velocity of gas bubbles.

A 96 liter rectangular fluidized bed was used, containing glass beads with a size fraction of 355μ to 250μ. Air was the fluidizing medium, with gas velocities ranging from 1.2 Umf to 2 Umf. The probe position was varied from 35 to 55 cm above the distributor, and 0 to 8 cm from the bed centerline. The bubble size distribution was fit to a truncated gamma function. It was also found that the Davies-Taylor Equation for bubble velocity was inadequate to fit the data, since the velocity varied significantly with the position in the bed.

Motion pictures were also taken in a two-dimensional bed to obtain qualitative information on bubble characteristics.

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