Mixing and Dispersion

Inverters offer many benefits over traditional mechanical drives with fewer moving parts, larger speed ranges, broader horsepower range, and reduced maintenance.  But they do have limitations the largest of which is their torque characteristics.  sss

Review of the function and operation of planetary-centrifugal mixers. Published July 2010, Adhesives and Sealants Industry Magazine.

Rapid changes in temperature of the heat transfer media can thermally shock the equipment. Typically, thermal shock is defined as changing the cooling or heating media at the jacket inlet more than 25 F per minute.

To transfer torque from the shaft to the blade, manufacturers use a number of configurations. The two most common are bore and keyway and bore and pinholes.

The design of a dispersion system begins by defining the batch size and product characteristics. From there we can begin to determine blade size, types, and number which will then allow us to define shaft rpm and horsepower requirements.

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Blade Speed (tip speed), measures how far a point on the outer most edge of the disperser blade travels in a given amount of time

Of all the "Rules of Thumb" the issues resulting from this pose the most severe issues. While not difficult to calculate, Blade Horsepower does not correlate well to a simple Volume to power relation. Most disperser manufacturers rely on a modification of the agitator horsepower relationship.

Beyond impeller bore configurations, with the Conn styles as well as other louvered or vented styles open area in the center of the impeller must also be considered. Typically, reinforcing discs, taper plates, sandwich the blade to stiffen the disperser disc. Due to the louver placement on the conn blade, the size of these disks, and with small sizes - the diameter of the mounting hub must be considered.

Due to the high tip speed of the dispersion blade, dispersion blades are subject to wear. Depending on formulations this wear can be severe. DisperseTech offers several wear treatments.

Most dispersion blades are formed from a circular disk of material, typically 304 stainless steel. Teeth are formed around the perimeter of the disk by cutting slits into the disk and bending the resulting tabs.

Mix Scale is used to quantify the mixing intensity needed for a given process as well as provide a frame of reference for mixing scale-up.