Effect of some solid properties on gas–liquid mass transfer in a bubble column

Abstract

The knowledge about the effects of solids on gas-liquid systems and the respective physical mechanisms are not yet totally clarified. In this work, the effect of the solids on the mass transfer characteristics in a bubble column was studied experimentally for the systems air/water/expandable polystyrene (EPS) beads and air/water/glass beads. Volumetric liquid side mass transfer coefficient, k L a, was determined under different solid concentrations (up to 30 vol.%), superficial gas velocities (up to 2.7 mm/s) and mean diameters (1100, 770 and 591 m for EPS and 9.6 m for glass beads). The presence of EPS solids affects negatively k L a being this effect more pronounced for the smaller particles. Also, a decrease in k L a occurs when the solid loading increases. Experiments done with large polystyrene particles (d p ≥ 591 m) contaminated with very fine EPS particles (d p ∼ = 0.1 m) indicate that very fine particles play an important role on gas-liquid mass transfer. Mass transfer experiments in a hollow glass spheres three-phase slurry showed a dual effect of solids loading on k L a, contrarily to what happens with the previous particles. These results can be associated with the different surface properties of the particles studied. An empirical correlation for k L a on the experimental variables was developed.

Estimation of liquid‐side mass transfer coefficient and liquid film thickness in a bubble column using single spherical bubble model

“…However, this variation is small and may be attributed to experimental measurement errors. Such deviation can be found in values reported earlier also …”

Gas–Liquid Mass Transfer Characteristics in a Gas–Liquid–Solid Bubble Column under Elevated Pressure and Temperature

“…The strong decrease can be attributed to the increase in the size of fast rising large bubbles in the churn-turbulent regime and the decrease of gas-holdup with high slurry concentration [7]. On the other hand, with slurry concentration increasing, the apparent liquid viscosity increased, and the surface renewal and mobility decrease which results in reduced k L [33]. This prevented the gas diffusion into liquid phase and the k L values decreased.…”

Mass transfer studies in shallow bubble column reactors

“…Some researchers found k L to be independent of U G [31][32][33][34]. Gopal and Sharma [35] found k L to decrease slightly with U G [12] while Lemoine et al [35] and Mena et al [36] found k L to increase with U G . Han and Al-Dahhan [19] found that k L increases with U G at low U G range but the increase in k L is not significant at high U G range.…”