Static mixer
 A promotional sample of a helical static mixer enclosed in a clear tubular housing |
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| Uses | Mixing |
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| Related items | Magnetic stirrer, vortex mixer |
A static mixer is a device for mixing two fluid materials. Normally the fluids to be mixed are liquid, but static mixers can also be used to mix gas streams, disperse gas into liquid or blend immiscible liquids. The device consists of mixer elements contained in a cylindrical (tube) or squared housing. These can vary from about 6 mm to 6 meters diameter. Static mixer elements consist of a series of baffles made of metal or a variety of plastics. Similarly, the mixer housing can be made of metal or plastic. Typical construction materials for static mixer components included stainless steel, polypropylene, Teflon, PVDF and polyacetal.
The overall system design incorporates a method for delivering two streams of fluids into the static mixer. As the streams move through the mixer, the non-moving elements continuously blend the materials. Complete mixing depends on many variables including the fluids' properties, tube inner diameter, number of elements and their design.
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[edit] Design
A static mixer's fixed, typically helical elements can simultaneously produce patterns of flow division and radial mixing:
- Flow division: In laminar flow, a processed material divides at the leading edge of each element of the mixer and follows the channels created by the element shape. At each succeeding element, the two channels are further divided, resulting in an exponential increase in stratification. The number of striations produced is 2n where 'n' is the number of elements in the mixer.
- Radial mixing: In either turbulent or laminar flow, rotational circulation of a processed material around its own hydraulic center in each channel of the mixer causes radial mixing of the material. Processed material is intermixed to reduce or eliminate radial gradients in temperature, velocity and material composition.
[edit] Applications
Today, static mixers are used for a wide range of different applications[1] in many different market segments. A common application is mixing two-component adhesives (e.g., epoxy) and sealants (see Resin casting). Other applications include wastewater treatment and chemical processing.[2] Static mixers can be used in the refinery and oil and gas markets as well, for example for desalting crude oil. In polymer production, static mixers can be used to facilitate polymerization reactions or for the admixing of liquid additives.[3]
[edit] History
The static mixer traces its origins to an invention for a mixing device filed on Nov. 29, 1965 by the Arthur D. Little Company.[4] This device was licensed to the Kenics Corporation and marketed as the Kenics Motionless Mixer.[5] Today, the Kenics brand is owned by Robbins & Myers, Inc.; however, there are also other suppliers of static mixers, including Sulzer Chemtech Ltd, Koflo Corporation, Statiflo and KOMAX Systems Inc.[citation needed]
[edit] References
- ^ "Markets & Applications". Sulzer Chemtech. http://www.sulzerchemtech.com/mixers. Retrieved 2011-07-04.
- ^ Bor, Thomas P., "The Static Mixer as a Chemical Reactor", British Chemical Engineering, Vol. 16, No. 7, 1971.
- ^ "Markets & Applications". Sulzer Chemtech. http://www.sulzerchemtech.com/mixers. Retrieved 2011-07-04.
- ^ C. D. Armeniades, et al., U.S. Patent 3,286,992 Mixing Device issued November 29, 1965
- ^ Arons, Irv (2008-07-23). "ADL Chronicles: The Disposable "Motionless Mixer"". Adlittlechronicles.blogspot.com. http://adlittlechronicles.blogspot.com/2008/07/disposable-motionless-mixer.html. Retrieved 2011-07-04.
