Scale-up of Rushton turbine-agitated tanks

Turbulent velocities have been measured with constant-temperature anemometry in three tanks of different geometries. Their diameters were 0.8, 1.88 and 2.09 m and they were equipped with 2, 3 and 4 Rushton impellers. The power input per unit mass has been measured with two methods: torque and temperature measurements. The turbulent parameters, turbulent kinetic energy and local energy dissipation rate, were evaluated as functions of power input per unit mass, and impeller Reynolds number, both in the impeller flow and in the bulk flow. The impeller zone, the major turbulence-generating region, exhibits steeper slopes than the bulk zone, where the turbulence production is lower. The normalised turbulent kinetic energy and local energy dissipation rate are compared for the three reactors resulting in two correlations for the impeller flow, which can be used for scale-up purposes. The results presented here show the influence of the ratio of bulk zone volume to impeller zone volume on the distribution of the power supplied to the reactor.