Liquid-Solid Mass Transfer in a Three Phase Draft Tube Fluidized Bed Reactor

Liquid-solid mass transfer coefficients in a three phase draft tube fluidized bed reactor have been measured using spherical ion exchange particles. The particle diameters ranged from 655 to 1119μm and solids volume fractions of approximately 5 and 10% were employed in water at 28°C. The experimental data can be successfully correlated using a Reynolds number derived using Kolmogoroffs theory of isotropic turbulence, although it is doubtful whether isotropic turbulence actually prevails in the fluidized bed over the range of conditions employed. Comparison with correlations determined for bubble columns and gas-liquid fluidized beds is performed. A model which considers the draft tube reactor as comprising two distinct fluid mechanical regions is developed to explain the apparently lower values of mass transfer coefficients obtained in a draft tube as opposed to conventional fluidized bed reactor.