Rotor stator mixer

Compact heat exchangers MicroChannel heat exchangers Rotor/stator mixers Rotating packed-bed Centrifugal adsorber... 

Rotor bodies, in steam turbines, 23 231 Rotor electrostatic separators, 16 643-644 Rotor rotating converter, 16 151 Rotors, molecular, 17 59-61 Rotor spinning cotton yarn, 3 17 Rotor-stator devices, 10 127 Rotor-stator disperser, 3 701 Rotor-stator mills, 13 65 Rotor-stator mixers, 16 674-675 Rotosil process, 22 412 Roughages, as ruminant feeds, 10 863 Roughing, in mineral separation, 16 604 Roughing services, magnetic drums used in, 15 446... 

Sparks, T. G., Brown, D. E. and Green, A. Assessing rotor/stator mixers for rapid chemical reactions using overall power characteristics (BHR conference series. Publication 18. Mechanical Engineering Publications Ltd. London, 1995). 

High-intensity inline devices are often used to mix fluids in the process industries. Such devices include simple pipes, baffled pipes, tees, motionless mixers, dynamic mixers, centrifugal pumps, ejectors, and rotor/stator mixers. In addition to their traditional application in physical processes such as mixing and dispersion, such devices can provide very effective environments for mass transfer and chemical reaction to take place. Furthermore, combining effective inline mixing with heat transfer is the basis of combined heat exchanger reactors (HEX reactors). 

Figure 10.20. Commercial in-line rotor stator mixers.

The rotor-stator homogenizer is one of the most commonly used pieces of equipment in the pharmaceutical industry. Although they have limited capability in achieving very fine droplets or particles, rotor-stator mixers are capable of handling liquids at much higher... 

Anchor mixers may be used in combination with other types of mixers, such as turbine mixers, high-shear mixers, or rotor-stator mixers, which were described in the previous subsection. Such mixers can be placed on a vertical shaft midway between the anchor shaft and blade. A secondary mixer can promote top-to-bottom motion and also limit bulk rotation of the fluid. A stationary baffle is sometimes placed between the anchor shaft and rotating blade to limit fluid rotation and enhance shear. 

Many types of multishaft mixers do not require planetary motion. Instead the mixers rely on an anchor-style impeller to move and shear material near the tank wall, while another mixer provides a different type of mixing. The second or third mixer shafts may have a pitched-blade turbine, hydrofoil impeller, high-shear blade, rotor-stator mixer, or other type of mixer. The combination of multiple impeller types adds to the flexibility of the total mixer. Many batch processes involve different types of mixing over a range of viscosities. Some mixer types provide the top-to-bottom motion that is missing from the anchor impeller alone. 

Rotor-stator mixers Slotted ring or impeller, along with slotted stator Either, often continuous 1 < d32 < 50 pm Sparse data for scale-up need extensive testing... 

Bourne, J.R. and J. Garcia-Rosas (1986). Rotor stator mixers for rapid micromixing. Chem. Eng. Res. Des. 64, 11-17. 

Hanselmann, W. and Windhab, E. Foam generation in a continuous rotor-stator mixer. Bubbles in Food, G.M. Campbell, C. Webb, S.S. Pandiella and K. Niranjan, eds., Eagan Press, USA, pp. 65 - 73,1999. 

Stabilized by Brownian motion Emulsifiers, ultrasonic devices, rotor-stator mixers,... 

Other types of equipment such as static (motionless) mixers, rotor-stator mixers, and impingement mixers are used to create dispersions (see Section 9.9). 

The emulsion-based processes, such as complex coacervation or interfacial polymerization, are best suited for preparing capsules from a few microns to a few hnndred microns. Emnlsification conditions are controlled to produce capsules of varying size. Snrfactants can be introdnced to adjust interfacial tension and further direct the emulsified droplet size. Paddle stirring, rotor-stator mixers, high-pressure homogenization, membrane emnlsifiers, or other high shear processes can all be used to control droplet size. 

Emulsions are ubiquitous in consumer applications, including pharmaceuticals, food products, adhesives and personal care products. Product characteristics are influenced both by the chemical formulation and by the processing technology employed. Traditionally, emulsions are formed under high shear conditions using static mixers, ultrasound devices, homogenizers or rotor/stator mixers. Compositions and process conditions are often over-designed to ensure that product requirements are met [2]. 

Dispersion will take place in a mortar or by means of a rotor-stator mixer, see further Sect. 29.7.1. An alternative method may be the use of the precipitation method (see Sect. 29.2.3). 

An example of a method for dispersing is given in Table 5.25. The active substance nitrofurantoin is hydrophUised by mixing it with silica. The thickening agents are processed into a base solution. Subsequently the hydrophUised substance is dispersed in that base. The example uses a rotor-stator mixer preparation method. 

Method of preparation with a rotor-stator mixer ... 

Checks for the absence of lumps or agglomerates a simple visual inspection may be sufficient if using a rotor-stator mixer, there should not remain any lumps... 

The focus in this chapter is on small scale preparation with a mortar and a pestle, a rotor stator mixer or an ointment miU. For preparation on a larger scale pharmacies in several countries use the mixing-dispersing apparatus Stephan mixer. This mixer exists in various models and is suitable for the preparation of almost aU cutaneous preparations (see Sect. 28.6.1). 

If a rotor-stator mixer is used, its mixing time and speed have to be limited in order to minimise the inclusion of air. As the inclusion of air cannot be completely avoided, the preparation has to be prepared by weight not by volume. 

For the preparation of batches up to 5(X) g a rotor stator mixer is recommended. With the rotor stator mixer carbomer is moistened and dispersed in the aqueous phase in which water soluble substances such as disodium edetate have already been dissolved. Herewith a somewhat viscous solution is created. Adding an alkali reacting substance causes deprotonating of carbomer and thereby an increase of... 

In this preparation, first a gel of carmellose is prepared in a portion of the cold water using a rotor-stator mixer. Then chloramphenicol palmitate is dissolved in a mixture of hot polysorbate 80 and propylene glycol. Polysorbate 80 thus functions here as a part of the solvent mixture. The hot clear solution is added to the aqueous gel tmder intensive stirring with... 

The flash point of flammable substances (see Table 26.11) gives an indication whether measures should be taken to prevent fire. Especially if the flash point of a substance is lower than about room temperature, it is necessary to ensure that there are no incendiary sources that may come into contact with the vapour near the liquid. Incendiary sources used in preparation processes may be a gas flame, but may also be electric devices that are not automatically explosion-proof, such as some ointment mills, rotor-stator mixers and refrigerators. 

This section discusses subsequently the Stephan mixer, the rotor-stator mixer, the planetary mixer, the mortar with pestle, the beaker mixer/blender, the three roll mill, the coffee grinder, the Topitec mixer and Unguator mixers. 

At maximum speed the mixer produces shearing forces at such an extent that they emulsify mixtures of water and oil. Only the rotor-stator mixer generates a higher shear force in fluids. During mixing an appreciable rise in temperature will occur, especially at higher speeds. If a mantle is available the contents of the bowl can be heated or cooled. The application of vacuum is relevant if air must be prevented from being whipped into the mixture. 

---