Virtually any industrial process depends entirely on having the raw materials properly stirred or mixed. Over the course of the years, Veenbrink RVS has specialised in a wide range of agitators. These are sometimes supplied by third parties, although generally we completely calculate, design and manufacture them ourselves.
At Veenbrink RVS we make a distinction between stirring and mixing. We define stirring as keeping the product in motion or homogenising the product by slowly stirring it. During this process there is no phase transition or chemical reaction. Examples include powders that need to be mixed together or a cream that must remain in constant motion to ensure optimal heat transfer with the wall. This is often associated with high viscosity, a low RPM and a relatively low scale of agitation.
Mixing is positioned at the other end of the spectrum. In contrast to stirring, there is a phase transition or chemical reaction during mixing. Examples include dissolving a solid substance, such as sugar, in a liquid, such as water, as well as emulsifying two difficult-to-mix liquids such as oil and water. A high RPM with high shearing forces are important here.
The positioning and orientation of an agitator or mixer determine the ultimate effect. Large gate blade or anchor agitators, possibly equipped with scrapers, are logically placed in the middle of the tank. To prevent the medium from simply only rotating, baffles are sometimes required. Fast-turning mixers operate optimally when they are placed 1/6 or 1/10 of the diameter off-centre. Due to the construction and the forces operating on it, a vertical orientation is always preferred, although this is not always possible geometrically.
Furthermore, the geometry and operation of a mixer or agitator also depends on the geometry of the head, and especially the bottom. One process may require a light or heavy cone, while yet other processes may require a torispherical design.
Important properties that must be considered are the required scale of agitation, RPMs, viscosity and shear force.
Aside from the fact that the drive and seal must be correctly constructed, the type of impeller determines how the method of stirring or mixing is effected. Important properties that must be considered are the required scale of agitation, RPMs, viscosity and shear force. High shear forces are found in sawblade and rotor-stator mixers. An anchor, gate blade or screw agitator is used for slow viscous stirring.
In addition, elements such as the minimum mixing level, and the degree of sterility and sanitation may also be determining factors. When these factors are of importance, magnetic agitators or bottom mixers are often used.
An efficient low shear agitator. The blade is slightly curved and is at a slight angle.
Suitable for homogenizing and suspending low viscosity media. The flow pattern shows strong axial suction.
The agitator creates a radial flow pattern at higher speeds and can create a vortex.
The flow pattern is similar to the propeller. However, a stronger radial flow is formed compared to the propeller.
The bottom mixer is used when there is a lack of space on top or when stirring with a low minimum level.
The agitator creates a high shear, which is why it is often used for mixing and dispersing powders in a liquid.
The agitator consists of a rotor that rotates at high speed in a stationary stator. As the rotating blades move past the stator, they slide off the contents.
A slowly rotating stirrer for temperature transfer and/or to keep the media homogeneous.
For different processes in one tank, a dual stirring system can be applied by means of the design of an anchor agitator.
The agitator creates a strong axial/tangential flow. This will push the media down or up.
The UZ agitator is used where there is a combination of mixing and keeping an easily settling or reasonably viscous product homogeneous.
Is especially for mixing high-viscosity products, but can efficiently handle low-viscosity process stages. The agitator can perform a wide variety of process tasks.
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