A Selection Guide to High Speed Dispersers
- May 19, 2020
- Posted by: firstname.lastname@example.org
- Category: IS, Lab & Analytical Instruments
What is a High Speed Disperser?
High Speed Disperser is a type of mixer used in the manufacture of chemicals, plastics, coatings, inks, paints, adhesives, composites and many other products. Its function is to incorporate, uniformly distributing, dissolving and wetting powders into liquid and break down particle agglomerates to produce a fine dispersion.
How Does It Work?
Conventional High Speed Dispersers consist of a driven vertical shaft and dispersing blade. The blade rotates and imparts high shear forces to create a radial flow pattern within a stationary mix vessel. The blade creates a vortex by continuously drawing product components to the blade’s sharp edges. The blade surface then mechanically tear apart solids thereby reducing the particle size, dispersing and dissolving them into the liquid to yield a homogeneous product.
How To Select The Right High Speed Disperser?
- Viscosity – make sure it is able to mix the viscosity range of your product. The materials are ideally thixotropic (shear thinning) and flow well under shearing/mixing conditions.
- Batch size – Determine the optimum batch size to match with the specifications of the high speed disperser.
- Vessel design – A round with a dished bottom vessel design promotes good flow and minimizes the possibility of dead spots with unmixed materials. A flat or sloped bottom is commonly used. In general, a vessel with the same diameter and height is preferred. 20% freeboard is recommended for product vortexing to prevent material from splashing over the top of the vessel. The blade should be positioned 0.5 of the blade diameter off of the vessel bottom. The vessel diameter should be 3 times the blade diameter. The desired full batch level at rest should be 1.5 blade diameters above the blade.
- Blade size and speed – The blade diameter should be about 1/3 of the diameter of the vessel. Power consumption depends on the diameter of the blade, the density of the products and the mixing speed. Typical disperser power requirements are in the range of 10 HP per 100 gallons of product. Normal blade is speed is in the range of 4800 – 5200 fpm (feet per minute).