Gas-liquid contacting with axial flow impellers

We focuse on the gas-dispersion characteristics of axial flow impellers. Various impellers are compared: an inclined blade impeller with flat blades, an A315 impeller and a Leeuwrik impeller. The goal is to gain insight in the gas-dispersion properties of such axial flow impellers. Therefore, the effects of impeller position and sparger geometry on flow pattern, power consumption and mass transfer are studied in a vessel 0.444 m in diameter, using liquids of different viscosity. The power consumption is strongly related to the different flow patterns and different types of cavities. Under certain conditions time-dependent, asymmetrical flow patterns can occur. The sparger type influences both the power needed to prevent flooding and the overall mass transfer coefficient k l a. The liquid viscosity does not affect the basic hydrodynamic phenomena in the vessel for viscosities not exceeding 80 m Pa s