Hydrodynamic effects play important roles in fluidized bed
combustion processes. Since the motion of "bubbles" is an important
influence on fluidized bed heat transfer, a better understanding of their
behavior is necessary for improving the design of fluidized bed boilers.
Using a two-dimensional bed, silica sand particles were fluidized with
air at room conditions. The bubbling bed was videotaped, and both
qualitative and quantitative information were gathered. Bubble
characteristics such as size, rise velocity and frequency were studied while
particle size and superficial gas velocity were varied. Results were
compared with some existing theories and other similar research. The
effect of internal surfaces at several heights in the bed was also studied.
General bubble behavior agreed well with descriptions from previous
research, and the expected spherical-cap bubble shape was observed. Both
bubble size and rise velocity increased with particle size and with fluid
velocity. Bubble frequency increased with fluid velocity, but decreased with
increasing particle size and height in the bed. These results agree with
previous work done using optical probes to measure bubble characteristics.
Comparisons of data with empirical models showed general agreement. The
presence of internal surfaces had the effect of reducing the bubble size, rise
velocity, and frequency, and also of reducing the influence of changing
particle size and superficial velocity on the bed behavior. / Graduation date: 1992
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/37017 |
| Date | 06 May 1992 |
| Creators | Freeman, Lisa Nalani |
| Contributors | Welty, James |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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