Hydrodynamics in Three-Phase Stirred Tank Reactors with Non-Newtonian Fluids

Abstract

Hydrodynamic characteristics have been studied in three-phase stirred tank reactors with non-Newtonian fluids. Critical impeller speeds for solid suspension and liquid-phase mixing times were measured. With increasing gas flow rate, solid loading, and non-Newtonian flow behavior, the critical impeller speed for solid suspension increased. The experimental data for non-Newtonian fluids were reasonably correlated by the available equations generalized by replacing the Newtonian viscosity by the apparent viscosity for a non-Newtonian fluid. An increase in the liquid-phase mixing time due to solid loading was obtained in both Newtonian and non-Newtonian fluids. Although the introduction of gas caused a decrease in the mixing time for water, the mixing time in non-Newtonian fluids increased by the gas dispersion. The model for liquid-phase mixing time based on the energy dissipation rate fit the experimental data reasonably.