Mixer double-motion

Fig. 111. A double-motion paddle mixer for premixing Thiokol propellant (Thiokol Chemical Corporation, Redstone Arsenal, according to Warren [5J).

Double-motion paste mixers (a) pony mixer (b) beater mixer. 

Double-Motion Mixers. As the name implies, double-motion mixers have a combination of mixer motions. Many double-motion mixers are a combination of a high viscosity, close-clearance mixer and high-shear mixer. The high viscosity part of the mixer provides bulk motion of the fiuid(s), especially near the tank walls, and the high-shear mixer creates dispersion, often of two phases, either two liquids or a liquid and solids. 

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. 

White [23,24] observed the circulatory flow behavior using markers with flow visualization technique in the R-R handed screw and double-flighted rotors mixer (Figure 8). This makes possible measurement of the circulation time as a criteria of mixing. Since the flow visualization experiments have limitations in observing the overall flow motion in the mixer, the following experiment was carried out to determine the distribution of elastomers. 

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