Couette mixer

Fig. 7. Diagram of the Couette mixer. The premixed emulsion, initially located in the syringe, is forced by a piston into the gap between the rotor and the stator. The sheared emulsion is collected at the top of the mixer...

Figure 1.5. A sketch of the so-called Couette mixer for preparation of monodisperse emulsions. Reprinted with permission from Mabille et al. [44]. Copyright (2000) American Chemical Society.

Couette Mixer - To further investigate the physics of the electrification process in transformer oil/cellulosic systems, a compact Couette flow system of coaxial cylinders for electrification measurements is shown in Fig. 4, where the inner cylinder can rotate at speeds giving laminar and turbulent flows as well as the transition cellular convection regime (Melcher et al., 1986 Lyon, 1987). The cylinder walls on either side of the oil gap can be bare metal or can be covered with oil-impregnated paper used in transformers. 

Figure 6.46 Schematic diagram of a Couette flow mixer with a tracer line.

Faure, A. Grimsey, I.M. Rowe, R.C. York, P. Chff, M.J. Apphcability of a scale-up methodology for wet granulation processes in coUette gral high shear mixer-granulators. Eur. J. Pharm. Sci. 1999, 8, 85-93. 

The Taylor-Couette reactor (see Chapter 5) is also a rotor stator mixer, but is discussed separately. Units such as the Marbond HEX-reactor demonstrate mixing plus reactions plus heat transfer in one unit, and these are also discussed in Chapter 5. 

A technique which avoids this problem is to decouple mixing from extrusion. An arrangement used by the author is shown in Figure 8.17 [17]. The primary objective was to obtain data on the influence of cavity size of the cavity transfer mixer (CTM) (described in Section 9.3). At the same time a variety of mixers were evaluated in an attempt to compare this particular mixer with a range of known mixing devices. An equal length of screw and a plain annulus (like the Couette model in Chapter 2) were used as controls. In addition to mixing performance, data was required on power consumption, temperature rise, and pressure drop. 

---