Static Mixers Need to Know with process engineers – For the past week or so I have been studying Static Mixers. It also made me think that I should be sharing what I have read and understood. The initial part which is a word description has been provided in the following text. However, the rough application guide for various commercial static mixer models and the pressure drop for the more popular static mixer models from manufacturers of repute could not be provided in the text. The Excel workbook provided as an attachment repeats the text description provided below. In addition to providing the rough application guide as a table and the pressure drop ratios for the popular commercial static mixer models. The Excel workbook also lists the leading manufacturers of static mixers and provides direct hyperlinks to their catalogs.
Motionless Mixers
Static or motionless mixers use stationary-shaped elements inside pipes or conduits to divide, divert, twist, and recombine flowing material. The dividing, stretching, and recombining processes lead to thinner and thinner striations in viscous materials to achieve uniformity. Molten polymers usually are in laminar flow and have no radial exchange when flowing. Thus, temperature gradients can form and propagate. Heating and cooling of these materials through the wall is very difficult. This is because of the residence time distribution associated with the laminar velocity profile. The material at the center moves much faster than the material at the wall. It also has less contact time because of the poor conductive heat transfer at the center. These devices would reduce radial thermal gradients that occur in polymer processing.
One of the first commercial units was the inline static mixer. In the mixer, a set of twisted elements with left- and right-hand twists caused the material to move from the wall to the center and from the center to the wall. After passing through a number of these elements, the fluid homogenizes concerning age. It also has a various composition and temperature. Static Mixers Need to Know for process engineers need to know that these devices were called motionless mixers or static mixers because the mixer did not move, although the liquid did. The term static mixer was originally copyrighted, but now people commonly use the term for all such in-line motionless mixers.
Over the years a large number of companies have produced Inline Pipe mixers all based on the principle of moving the streams radially by a series of metal baffles. These baffles may consist of twists of metal and corrugated sheets. Also, parallel bars, small-diameter passages, or tabs sticking out from the wall. They are essentially plug-flow devices with some small degree of back mixing, depending on the exact design.
Market Segments
Today, many different market segments have established static mixers and are using them for a wide range of applications. A common application for static mixers includes mixing two component adhesives (e.g. epoxy) and sealants. Other applications include wastewater treatment and chemical processing. The Inline mixers can also be used in the refinery and oil & gas market for example for the desalting of crude oil. In polymer production, static mixers can homogenize polymer melts. They also uniformly mix liquid additives into the molten polymer.
I would appreciate comments from the knowledgeable forum members for any further insight on Static Mixers Need to Know. Their applications, and any other information that could prove useful to the chemical engineering community.
You can download the spreadsheet here: