Mass transfer from solid particles to liquid in gas-liquid-solid fluidization was experimentally investigated by means of an electrochemical method with 7-9 particle electrodes fixed at various radial positions in a column of 82.9 mm i.d. Supplementary measurements were also conducted for the solid-to-liquid mass transfer in single liquid flow, gas-liquid two-phase upflow and liquid-solid fluidization.
The effects of particle size and liquid and gas flow rates on the solid-to-liquid mass transfer coefficient, K_s, in all the systems were investigated and the mass transfer coefficient was well correlated by the following equation proposed by Ohashi et al. for K_s in a packed bed with single liquid flow.
Sh_s = 2 + O.51(E^1/3d_p^4/3/V₁)^0.06Sc^1/3
where E is the energy dissipation rate per unit mass of liquid, d_p the particle diameter, v_l the kinematic viscosity of liquid, Sh_s the Sherwood number and Sc the Schmidt number. The value of E was expressed by the sum of the kinetic energy supply terms due to viscous drag force across a particle and to gas agitation.