Abstract
The gas-slurry-solid fluidized bed is a unique operation where the upward flow of a liquid-solid suspension contacts with the concurrent up-flow of a gas, supporting a bed of coarser particles in a fluidized state. In the present study we measured the gas holdup, the coarse particle holdup, the cylinder-to-liquid mass transfer coefficient, and the cylinder-to-slurry heat transfer coefficient for controlled slurry concentrations. The slurry particles were sieved glass beads of 0.1 mm average diameter and their volumetric fraction was varied at 0, 0.01, 0.05 or 0.1. The slurry and the gas velocities were varied up to about 12 and 15 cm/s, respectively. The coarse particles fluidized were sieved glass beads of average diameters of 3.6 and 5.2 mm. The phase holdup values for the gas, slurry, and coarse particles were separated on the basis of the measured properties including axial static pressure distribution, axial distribution of the liquid holdup evaluated from an electro conductivity method and the bed height. The gas holdup values were correlated by a dimensionless equation, and the solid holdups (voidages) were well correlated by modifying an empirical model proposed by Hirata et al. (1995) for the viodage of the three-phase fluidized beds. The heat transfer coefficient and the mass transfer coefficient can be correlated well by a unified correlation in terms of the specific power group, including the energy dissipation rate per unit mass of slurry with small deviations between the calculated and experimental data values for both the mass and heat transfer coefficients.
