Abstract
The mixing characteristics of high-viscosity liquid in stirred tanks were investigated from measurement of the concentration response curves by injecting tracer in the tanks, and it was confirmed, by comparing the results of the concentration response curves calculated from the circulation time distribution, that the circulation time distribution can be used to predict the concentration response curve that represents the mixing performance. The effect of diffusive mixing was found to be significant in the concentration response curve obtained experimentally, particularly in the case of paddle or turbine impellers in the range of Reynolds number less than 10. The characteristic values of mixing both observed and calculated showed a similar tendency and it was concluded that paddle and turbine impellers are preferable for mixing in the Reynolds number range greater than 20, and helical ribbon and helical screw impellers for less than 20. An attempt was made to correlate the parameters characterizing the circulation time distribution with operating conditions, and a method of estimating the characteristic values of mixing from the parameters of the circulation time distribution was obtained.
