Mixing Time in an Agitated Vessel Equipped with Large Impeller

Mixing times for large impeller, Maxblend, Hi-F Mixer and Sanmeler in addition to double helical ribbon were measured precisely in a wide range of Reynolds number. As well known, the dimensionless mixing times for helical ribbon impeller become nearly constant in the laminar flow region. On the other hand, it was recently reported that those for Maxblend are almost inversely proportional to the Reynolds number. In this work, the mixing times and power consumptions were investigated experimentally for Hi-F Mixer and Sanmeler, which have inclined upper blade in addition to a large bottom paddle and are the other types of large impellers than Maxblend, and compared with those obtained in this work for Maxblend and double helical ribbon impeller. As a result it was found that the dimensionless mixing times for Hi-F Mixer and Sanmeler also decrease but more slowly with an increase in Reynolds number than those for Maxblend. The difference in dependencies of mixing times on Reynolds number were explained by the geometrical configurations of these large impellers.