Effect of solid particles on the volumetric gas liquid mass transfer coefficient in slurry bubble column reactors

The effect of solid particles on the volumetric gas liquid mass transfer coefficient k(l)a(l) in slurry bubble column reactors was investigated in the present work. k(l)a(l) was measured for an air-water-glass bead system using the dynamic oxygen absorption technique. Three solid concentrations and two particle diameters were used. Solid particles had a negligible effect on k(l)a(l) due to two opposite effects. First, a fraction of the particles tends to be located in the bulk liquid, altering its viscosity. In the heterogeneous regime, increasing the solid concentration enhances bubble coalescence, which led to an increase in size and, as a result, a decrease in the gas-liquid interfacial area a(l). Second, another fraction of particles moves to the bubble surface due to the collision phenomenon and tends to accumulate in the liquid film, resulting in local turbulence and an increase in the liquid-side mass transfer coefficient k(l). The hydrodynamic effect mechanism was the governing mechanism of the effect of solid particles on gas-liquid mass transfer within the range of the investigated operating conditions. (C) 2020 Elsevier Ltd. All rights reserved.