Particle flow behavior in three-phase fluidized beds

Non-uniform flow behavior of fluidized solid particles in three-phase fluid ized beds has been analyzed by adopting the stochastic method. More specifi cally, pressure fluctuation signals from three-phase fluidized beds (0.152 m ID x 2.5 m in height) have been analyzed by resorting to fractal and spec tral analysis. Effects of gas flow rate (0.01-0.07 m/s), liquid flow rate ( 0.06-0.18 m/s) and particle size (0.001-0.006 m) on the characteristics of the Hurst exponent, spectral exponent and Shannon entropy of pressure fluct uations have been investigated. The Hurst exponent and spectral exponent of pressure fluctuations attained their local maxima with the variation of li quid flow rate. The Shannon entropy of pressure fluctuation data, however, attained its local minima with the variation of liquid flow rate. The flow transition of fluidized solid particles was detected conveniently by means of the variations of the Hurst exponent, spectral exponent and Shannon entr opy of pressure fluctuations in the beds. The flow behavior resulting from multiphase contact in three-phase fluidized beds appeared to be persistent and can be characterized as a higher order deterministic chaos.