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Interpretation of acoustic signals from fluidized beds

J.S. Halow
Morgantown Energy Technology Center
Morgantown WV 26505

C.S. Daw
Oak Ridge National Laboratory
Knoxville TN 37932-6472

C.E.A. Finney, K. Nguyen
University of Tennessee
Knoxville TN 37996-2210

Rhythmic "whoosing" sounds associated with rising bubbles are a characteristic feature of many fluidized beds. Although clearly distinguishable to the ear, these sounds are rather complicated in detail and seem to contain a large background of apparently irrelevant stochastic noise. While it is clear that these sounds contain some information about bed dynamics, it is not obvious how this information can be interpreted in a meaningful way. In this presentation we describe a technique for processing bed sounds that appears to work well for beds with large particles operating in a slugging or near-slugging mode. We find that our processing algorithm allows us to determine important bubble/slug features from sound measurements alone, including slug location at any point in time, the average bubble frequency and frequency variation, and corresponding dynamic pressure drops at different bed locations. We also have been able to correlate a portion of the acoustic signal with particle impacts on surfaces and particle motions near the grid. We conclude from our observations that relatively simple sound measurements can provide much diagnostic information and could be potentially used for bed control.

Halow JS, Daw CS, Finney CEA, Nguyen K (1996). Interpretation of acoustic signals from fluidized beds. Proceedings of the 5th World Congress of Chemical Engineering (AIChE) (San Diego, California USA; 1996 July 14-18): VI-291-VI-296.
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