Types of Static Mixers

Examples of the most commercially significant static mixers are, by manufacturer Chemineer, Inc. (Kenics) 

KMS twisted ribbon or bowtie type, with alternating left- and right-hand twists. An element is 1.5 or 1.0 diameter in length. The KME variation is edge sealed to the tube wall. See Visual Mixing CD. 

KMX a series of inclined retreat curve rods forming an X lattice alternating in direction every diameter an element is one diameter in length. 

HEV a series of four tabs spaced around the pipe. An element consists of four tabs symmetrically placed. Axially, the tabs are about 1.5 diameters apart. See Visual Mixing CD. 

See Eigure 7-16 for an illustration of some of these static mixers. There are many more types, and new ones are being developed constantly. Most of the above are characterized by good vendor technical information. Omission of a type from the list above, however, does not necessarily indicate an inferior product, just a lack of quantitative information. Many manufacturers have copied the basic 

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Figure 7.26. Twisted-blade type of static mixer elements...

Figure 7.27. Twisted-blade type of static mixer operating in the laminar flow regime (a) Distributive mixing mechanism showing, in principle, the reduction in striation thickness produced (f>) Radial mixing contribution...

Figure 8 Various types of static mixers. (Courtesy Koch-Glitsch.)... 

Attempts to use these kinds of devices on low-viscosity materials showed that the flows did not twist and curl in quite that same fashion. In the low-viscosity region, pressure drop is a key factor. The second type of static mixer gets pressure drop through controlled channels, different types of static elements, as well as random placement of baffles, blades, orifices, or other devices inside the pipeline. 

For instance, with the Hi-Mixer (161), 6Q/6 = 4n. A factor of 5 is easy to obtain for m with respect to an empty tube, at the expense of a corresponding increase in pressure-drop. A comparison between the existing types of static mixers (162) shows that most of them have an equivalent effectiveness. The case of Sulzer-Mixers has been especially studied (163), including use with gases (164). 

Commercially available static mixer reactors (SMR) as large as 1.8 m in diameter are operating in the production of nylon, silicones, polystyrene, polypropylene, and other polymers. Removing heat from a highly exothermic reaction in a static mixer equipped with a simple cooling jacket is limited by heat transfer to small diameters, typically less than 6 in. A new type of static mixer has been developed to overcome laminar heat-flow transfer problems. It is called the SMR mixer-heater exchanger-reactor (Mutsakis et al, 1986). 

Fig. 8.4a-d Several types of static mixers a Kenics mixer b Sulzer SMV mixer c Sulzer SMX mixer and d Ross-ISC mixer from [416]... 

An increase in heat transfer of only a factor of 2 to 5 in the range Re < 2.300 has also been established for other types of static mixers (SMX and SMXL, BMX-D) [38]. 

Kabatek j., Diti P., Novak V., Hdax -a New Type of Static Mixer. Operation Characteristics and Comparison with Other Types, Chem. Eng. Process. 25 (1989), p. 59-64... 

This result assumes the static mixer is of the Kenics type that repeatedly divides the fluid into two portions (that is, one that follows the 2 model for striation thickness). See Ref 5 for details and results for other types of static mixers. Equa-... 

There are quite a few different types of static mixers (see Rauwendaal, 1986), but they all serve the same function. 

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