Impeller double-motion

Several types of impellers are used. The most common are the simple marine impeller and the highly efficient double-motion stirrer. The reactors are always suitably baffled. 

The double motion comes from two shafts with at least two impellers operating in the same tank. Other double-motion mixers have coaxial shafts with a close-clearance impeller and turbine impeller(s) operating at different speeds. Some mixers have shafts that move relative to the vessel, as in planetary motion mixers,... 

Double- and Triple-Shaft Mixers The planetary mixer is an example of a double shaft mixer. However, many different combinations of mixing actions can be achieved with multi-shaft mixers. One variation on planetary motion involves replacing one anchor-style impeller with a high-shear impeller similar to the one shown in Fig. 18-47. The high-shear mixer can be used to incorporate powdered material effectively or create a stable emulsion leading to a final batch of viscous paste or fluid. 

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