Blending Liquids of Differing Viscosities and Densities in Stirred Vessels

Mixing time measurements were carried out in turbulently stirred vessels with miscible liquids of differing viscosities and densities. Depending on the flow characteristics and liquid properties, three mixing regimes can be defined for buoyant additions: the stirrer controlled regime, the gravity controlled regime and the intermediate regime. While in the stirrer controlled regime, the dimensionless mixing times are equal to those for liquids of equal properties (about 30 for the geometry used), the gravity controlled values can be much higher. In the intermediate regime, the dimensionless mixing times can be anywhere in between.