Hydrodynamics of three-phase fluidized beds

Overall phase holdups, or value fractions, determined from a homogenous bed model, were combined with similar literature data to yield correlations for the overall gas and solid phase holdups. The overall gas holdup increased solid as the gas velocity was increased, while the overall solid holdup was decreased by increased liquid velocity and increased by increased particle diameter or solid/liquid density difference.

An electroconductivity technique was developed for use in the three-phase fluidized beds which allowed each of the phase holdups to be determined at any point in the column. The technique has shown the existence of a transition region as the bed goes from a three-phase to a two-phase system. The holdup profiles were fitted using the error function, and the mean and standard deviation of the solid holdup profile, along with the gas and solid holdups in the regions of where they were constant, were measured for each set run conditions. Use of these five, which were correlated with the physical of the systema studied, permits each of the three phase holdup profiles to be predicted. This gives the reactor designer more information concerning phase distributions than was available previously; thus it will reactors where local conditions throughout the bed must be considered.