Date of Award
Doctor of Engineering Science in Chemical Engineering
Chemical Engineering and Chemistry
Angelo J. Perna
Wing T. Wong
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.
Chu, Thomas Tai-Pai, "Use of an optical probe to measure bubble characteristics in gas fluidized beds" (1984). Dissertations. 1198.