Journal of Chemical Engineering of Japan, Vol.43, No.4, 355-362, 2010
Evaluation Method of Homogenization Effect for Different Stator Configurations of Internally Circulated Batch Rotor-Stator Mixers
In this study, we propose an evaluation method of a homogenization effect for different stator configurations of internally circulated batch rotor-stator mixers. The homogenization effect has been evaluated indirectly using a homogenization coefficient (C-h) based on the measured power number, estimated flow number, and calculated shear frequency derived from the number of rotor blades and stator holes. In order to estimate the flow number of an internally circulated batch rotor-stator mixer, the flow rate of an externally circulated mixer that had a similar rotor-stator configuration was used. As a result of C-h evaluation by operation with water, it is inferred that the homogenization effect is much higher with a smaller stator hole diameter and a larger number of stator holes. Our results also suggest that the clearance between the rotor and the stator has less influence on the homogenization effect than the hole diameter and number of holes. In the case of operation with a model product, we obtained the same trend for operation with water. From this fact, we consider that the performance estimation using C-h has a high degree of adequacy. The total energy dissipation rate that was contained in C-h could well account for the mean drop diameter in relation to mixing time. Our results demonstrate that we can compare and evaluate the homogenization effect for different configurations of rotor-stator mixers using the calculated C-h of the water mixing operation without actual product trials. This information could be useful for determining the optimum mixer design and appropriate mixer selection.