Statistical and frequency analysis of pressure fluctuations in spouted beds

Differential pressure fluctuation time series were obtained in two gas spouted beds of 80 and 120 mm I. D. at different axial and radial positions. Statistical and frequency analyses of the differential pressure fluctuation signals were employed to recognize and characterize the flow regimes in spouted bed, i.e. packed bed, stable spouting and unstable spouting. Spouting behavior in deeper spouted beds was found to be significantly different from that in shallow spouted beds. The pressure fluctuations in shallow beds were quite random, while those in deeper beds showed strong periodic behavior. When the operation mode in beds changed from the packed bed regime to the stable spouting regime in a shallow bed, the standard deviation increased sharply. Skewness was found to be independent of flow regimes. Power spectrum densities of different flow regimes have different characteristics and thus can be used to identify the flow regimes. The influence of sampling locations was also discussed.