|
Fulidized Zone Mixer
The World's Fastest, Most Effective Mixer
The fastest, most efficient mixing achievable today is realized in the S F Fluid Zone Mixer line. These new mixers, with their distinctive counter-rotating paddle action, represent an entirely new generation in mixer technology. They provide complete homogeneity - a mix variance that is less than 1% - in seconds rather than minutes. And they also prevent re-segregation if mixing cycles are continued beyond completion, even where the particles are of widely differing size and density.
At the conclusion of the cycle, the mix is discharges in bulk through large "bomb bay" doors at the bottom of the mixing chamber, thus eliminating another common opportunity for re-segregation
|
If liquid addition is necessary, it can be added directly or through spray nozzles mounted directly above the mixing chamber. More difficult liquid-addition needs are met through optional flow distortion bars or by the use of a pin-mill agitator that adds shear forces to integrate liquid as it is added to the mix.
High Throughout With Fragile Materials
With cycle times reduced to seconds and fast discharge, the new S F Fluid Zone Mixers can provide a through-put/per hour of up to 60 times their rated capacities. Also, the short cycle time and slow paddle speeds mean that even the most fragile materials can be handled without mechanical or friction induced heat damage.
A wide range of models with capacities from 0.2 to 175 cubic feet is available, fabricated in carbon steel, stainless steel or any other weldable alloy, and with or without liquid-addition capability.
Zero Gravity Mixing
Start - Three dissimmilar materials ar loaded into
the mixing chamber. After 2 seconds -
Mixing is already
well advanced. After 5 seconds -
The materials are thoroughly mixed. After 10 seconds - Continued mixing results
in no resegregation.
Two materials of identical particle size and density will proceed very quickly to a random mix if they are simply put into chaotic motion together. Most conventional mixers are based on this "chaotic motion" effect despite the fact that very few commercial mixes involve materials that are identical in size and density. They succeed to a greater or lesser extent by how they counter the tendency of the dissimilar materials to segregate by size and mass within the mixing chamber due to the effects of gravity.
A New Approach
The S F Fluid Zone Mixer design achieves its results by inducing chaotic motion in the mix while providing a free-fall, "zero-gravity" fluidized zone mixing area in which relative motion is also random regardless of particle size and density. The elements of the mix then quickly proceed to a random spatial relationship with each other as if they were physically identical.
The key to the speed and efficiency of a S F Fluid Zone Mixer is the specifically designed, overlapping paddles within the mixing chamber. The paddle blades induce chaotic motion. But also, with the paddles counter-rotating at the optimized tip-speed, the fluidized zone develops. Opposing forces, the combination of the lift of the paddles and the free-fall that follows the lift, effectively cancel out the force of gravity in the center of the mixing chamber. This is the S F Fluid Zone Mixer zero-gravity fluidized zone, the key to effective mixing.
Adding Liquids
For absorption or coatings, liquids can usually be added to the mix, either directly or through a spray nozzle. If large volumes are involved, the basic design can be enhanced by the addition of special liquid-addition features, the flow distortion bar and pin-mill system. These allow the liquid elements of a mix to be introduced more quickly and efficiently.
The flow distortion bar randomizes the liquid flow as it is introduced into the mix. The pin-mill system provides a shear force that works in combination with the fluidized zero-gravity zone. Its counter-rotating and stationary milling rods work to provide additional agitation to the surface of the mix immediately as it leaves the zero-gravity zone where liquid has been added. This assures even distribution of the liquid elements and prevents agglomeration.
The Process
. Twin Counter rotating shafts with angled paddles creates fluidized Zone for homogeneous mixing irrespective of size / shape of the ingredients in weightless condition.
. Fluidized Zone eliminates the gravitational force thereby facilitates to achieve uniform distribution of coarse and fine ingredients in very short duration.
. No frictional heat generation, ideally suitable for heat / air sensitive and hygroscopic powder ingredients homogeneous mixing. Gentle handling ensures no degradation for the ingredients.
. High speed Flow Distortion Bar creates a curtain of particles facilitates for uniform coating of viscous liquid ingredients.
. Flexible filling volume from 40-140%.
. Twin Bombay door mechanism ensures complete discharge of mixed product in short time.
Function and Accessories
Filling Level
The S F Fluid Zone Mixer has a very flexible filling level, where the mixer volume describes the working volume and not the total mixer volume. 100% working volume is nominal filling level, and the mixer can work from 40% to 140% filling. The same perfect mixing result will be achieved independent of bulk density and material properties. Add a few seconds more of mixing when operating at the filling borders, but a good mixing result will be achieved.
How the Mixer Works
The two shafts of the S F Fluid Zone Mixer are counter rotating, which lifts the material up in the middle of the mixer, also called the fluidized zone. The angular paddles are welded to the paddle shafts, which give an overlapping rotation in the middle of the mixer and sweeping the entire bottom of the mixer according to specified clearance. In the fluidized zone, the particles have freedom of movement, which again ensures that we achieve a fast and homogeneous mixture.
Liquid Addition - FDB
When liquid is added into fine powder (small particles), an FDB (Flow Distortion Bar) is used. The FDB is a rotor with radial pins. The pins throw the particles at high speed and create a horizontal curtain across the liquid stream. The single particles exposure to the liquid is short and ensures a good distribution of the liquid in the powder.
The mixer should have a filling of approximately 120% when the FDB is used.
Mixing and Breaking with PMS
PMS (Pin Mill Systems) is used when we need to break lumps in the mixture or need higher shear forces during mixing. This system consists of two high speed rotating shafts with welded pins mounted above the fluidized zone.
A hood with intersective pins is placed over the shafts and this ensures a proper stream of product and good crushing effect on the product.
The mixer should have approximately 120% filling when the PMS is used.
Tulip Knives
Tulip knives are mounted in the lower part of the mixer's end wall and are used for breaking of lumps at low filling. The tulip knives add high shear forces independent of the filling level
Cleaning of the machine is easier with the tulip knives and there is no need for a hood above the fluidized zone, which improve the availability.
|