The design of the VRM mixer is based on creating the 'multiple mass flow' principle in the mixing vessel. This mass flow is achieved by using a single-sided, mounted mixing screw placed in a central tube. The product to be mixed is transported through the tube from below into the mixing screw.
The mixing tube is equipped with 1 or more mixing heads. At the first mixing head, part of the product is added to the falling product mass via the openings in the mixing head. The same happens with the second and possibly third mixing head. The rest of the product is carried out at the top of the mixing tube.
In combination with the angle of the mixing heads and the outlet cone, different, separate mixing zones are created, resulting in a very high variety of mass flow. As a result, the VRM mixer can be used for mixing or homogenizing relatively small quantities of approximately 10-25 % of the total mixing tank capacity.
For optimal mixing, the mechanical mixing screw can be combined with a pneumatic system using the so-called 'Choke' effect. For this purpose a special fluidization cone is placed in the bottom of the VRM mixer, which adds metered air or inert gas to the product. The fluidized product can then easily be raised through the mixing tube.
The degree of filling of the mixing screw can then be checked by controlling the amount of air or gas: the mixing process can be fully controlled by increasing or decreasing the 'choke' effect. The fluidization facility is always used, even when absolutely non-fluidizable products are processed (such as plastic granules). This is because it enhances the product lift and reduces wall friction in the mixing screw, resulting in a negligible granules breakage and lower absorbed power.
A shorter mixing time is also obtained with fluidisable products. This combination ensures a very efficient operation and a very high mixing result.
Assembly VRM mixer
- Very short mixing time
- Relatively low energy consumption
- No segregation
- Large mixing capacity
- Can be built into existing silos and hoppers
- Also suitable for drying, cooling and degassing
- Capacities from 500 to 100.000 l
Versions and options
- Fluidisation base against bridging
- Dosage of dry and warm air for intensive drying or for keeping the product at a required temperature
- Dosage of dry and cold air in the mixer for intensive product cooling
- Agglomerate or add liquid substances during the mixing process by mounting spray nozzles in the mixer
- Easy, automatic cleaning and drying of the mixer by mounting spray nozzles in the mixing screw and mixing vessel
- Different mixing head designs, depending on the size of the mixer and the type of product