A high-shear mixer spreads, or transports, a single phase or material (liquid, solid, gas) into the main continuous phase (liquid), by which it will normally not be mixed. A rotor or impeller, together with a stationary component known as the stator, or rotor array and stators, is used either in a tank containing the solution to be mixed, or in a pipe through which the solution, to create shear. High-shear mixers can be used to make emulsions, suspensions, lyosols (gases dispersed in liquids), and granular products. It is used in industrial adhesives, chemicals, cosmetics, food, pharmaceuticals, and plastics for emulsification, homogenization, particle size reduction, and dispersion.
Video High-shear mixer
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The fluid undergoes shear when one region of fluid moves at different rates relative to adjacent areas. High-shear mixers use rotating impellers or high-speed rotors, or a series of inline implants or rotors, usually powered by an electric motor, to "work" fluid, create flow and shear. The tip velocity, or fluid velocity at the outer diameter of the rotor, will be higher than the speed at the rotor center, and this speed difference creates a shear.
The stationary component can be used in combination with the rotor, and is referred to as the stator. The stator creates a close-range gap between the rotor and itself and forms a very high shear zone for the material as it exits the rotor. The rotor and stator are combined together often referred to as the mixing head, or generator. The high-speed stator-rotor mixer can contain any number of generators.
The main design factors include the rotor diameter and rotation speed, the distance between the rotor and the stator, the time in the mixer, and the number of generators in the series. Variables include the number of rows of teeth, their angle, and the width of the opening between the teeth.
Batch mixer high-shear
In a high-shear batch mixer, the components to be mixed (whether liquids or powders in an unmixed liquid) are inserted from the top into the mixing tank containing the mixer on the rotating shaft at the bottom of the tank. A high-shear batch mixer can process a given material volume approximately twice as fast as an inline rotor-stator mixer from the same power rating; The mixer continues to be used where faster processing by volume is a key requirement, and unlimited space. When mixing the sticky solution, some products may be left in the tank, so it needs to be cleaned. However, there is the design of a high-shear batch mixer that cleans the tank as part of a running operation. Some high-shear mixers are designed to dry, limiting the amount of cleaning required in the tank.
Inline high speed intruders
In a high-shear rotor-stator mixer, the rotor-stator array is contained in a housing with an inlet at one end and an outlet on the other, and the rotor is pushed through the seal. The components to be mixed are pulled through the array of generators in a continuous flow, with the whole acting as a centrifugal pumping device. Inline high-shear mixers offer a more controlled mixing environment, take up less space, and can be used as part of a continuous process. Equilibrium mixing can be achieved by passing the product through an inline high shear mixer more than once.
Inline powder induction
An inline rotor-stator mixer equipped for powder induction offers the flexibility, capability, and portability to serve multiple mixed ships of almost any size. Easy operation and convenience maximize utility tools while simplifying material handling.
When used with a vacuum pump and a hopper, an inline shear mixer can be a very effective way of inserting the powder into the liquid stream. Known as high-shear powder inductors, this system has the advantage of keeping the process on the floor rather than working with heavy pockets on the mezzanine. The high shear powder induction system also offers ease of exchange with multiple tanks.
High-speed granulator
A high-shear granulator is a process arrangement consisting of an inline or batch height shear mixer and a fluid-bed dryer. In the granulation process, only solid components of the mixture are required. Fluids are used only as aids to process. The high-shear mixer processes the solid material down to the desired particle size, and the mixture is then pumped into a drying bed where liquid is removed leaving the granular product.
Ultra-high-shear inline mixer
In an ultra-high-shear inline mixer, high-shear mixing takes place in one or more through the rotor-stator array. This mixer is designed to direct the product to higher shear and larger amounts of shear events than the standard inline rotor-stator mixer, resulting in a very narrow particle size distribution. Sub-micrometer particle size is possible by using ultra high shear technology. To achieve this, the machine is equipped with a stator with a precision slot or slot through which the product is forced by the rotor. The rotor-stator array may also include mechanisms in which the flow momentum changes (eg by forcing it sideways through the stator), allowing for more processing in one pass.
Maps High-shear mixer
Mixing Equilibrium
High-shear mixers are used in industry to produce a mixture of non-naturally mixed feedstocks. When the total fluid consists of two or more liquids, the end result is an emulsion; when composed of solid and liquid substances, this is called a suspension and when the gas is dispersed throughout the liquid, the result is lyosol. Each class may or may not be homogenized, depending on the amount of input energy.
To achieve the standard mixture, the equilibrium mixing technique is used. The characteristic of the target is identified, so that once the mixed product gets that characteristic, it will not change significantly afterwards, no matter how long the product is processed. For dispersion, this is the size of the equilibrium particles. For emulsions, it is a measure of equilibrium droplets. The amount of mixing required to achieve the equilibrium mixing is measured in the tank rotation - the amount of times the material volume must pass through the high shear zone.
Use of high-shear mixing technology
High-shear mixers are used throughout the chemical process industry, wherever necessary to produce a mixture of non-naturally mixed feedstocks. These include:
- Pharmacy, preparation of suspension and granular products
- Paper preparation, bleaching and pulp preparation
- Food preparation, emulsions for seasonings, sauces, and sauces
- Making cosmetics and toiletries
References
Source of the article : Wikipedia
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