EXPERIMENTAL CHARACTERIZATION OF THE SOLID-PHASE CHAOTIC DYNAMICS IN 3-PHASE FLUIDIZATION

An experimental study of the solid phase dynamics in a three-phase flu idized bed reactor using heavy and light particles is carried out. A r adioactive particle tracking technique is employed to obtain extended time series of the tracer path. The tracer has the same properties as the rest of the particles in the bed. A rescaled range-analysis is app lied to time series of the fluctuating velocities to investigate the f eatures of solid phase turbulence. It is found that turbulence is anis otropic. In the axial direction, the correlations between the fluctuat ing velocities are persistent in time, indicating a superdispersive ax ial dispersion of the solids. Hence a constant axial dispersion coeffi cient, which is traditionally used in these reactors to represent the solid phase turbulence, only constitutes a lumped parameter hardly ext rapolable to different operating conditions, different systems, and di fferent geometries. The tracer path is also analyzed according to the theory of deterministic chaos. It is found that the solids motion is c haotic. An increase in the gas flow rate increases the values of the p arameters that quantify the chaotic behavior of the solids motion. Thi s analysis is found to constitute a promising tool to determine flow r egime transitions.