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Airmix
Blending and homogenising of granules and powders within a few seconds and without moving internals.
Function
The AIRMIX is an apparatus designed for mixing, blending and homogenising free-flowing bulk materials in batch mode. The mixing principle relies on directed compressed air pulses. The AIRMIX vessel (see diagram, item 1), which is designed as a silo, is filled with the products to be mixed. As soon as the batch has reached the requested size the feed opening is closed and the mixing process started. The air volume required for the process is generated by a compressor (diagram, item 9) and stored in a separate pressure vessel reservoir (diagram, item 8) before the start of the mixing process. A pneumatic control system (diagram, item 5) injects the stored compressed air into the product as compressed air pulses. The jet openings in the mixing head (diagram, item 6) provide for a defined flow direction of the compressed-air pulses and ensure very thorough mixing of the products. The entire mixing cycle of one batch takes no more than two minutes and usually consists of six mixing pulses with intervals in between allowing the air to separate from the product again. A bag-type dust collector (diagram, item 3) integrated into the top of the mixing vessel filters out the dust, and the cleaned air is discharged into the open.
Design features
Different sizes of mixing heads can be supplied, making the AIRMIX available for a wide range of applications and capacities. In addition to the standard steel version, the AIRMIX can also be built from stainless steel or special materials. The mixing head (diagram, item 6) is of a very simple design, with the compressed air flowing into the inner chamber via two inlets and from there being uniformly distributed into the product via jet openings. All components are metal seated and form smooth surfaces inside the mixing head. For handling materials involving an explosion risk the AIRMIX can be fitted with a rupture disk (diagram, item 2) or supplied as a 10 bar shock-pressure resistant unit. Since the AIRMIX does not feature any moving components, the apparatus represents no potential source of ignition during operation so that the ATEX Directive is not applicable to the AIRMIX itself.
Advantages
Even when handling very large batches and different bulk weights of the components to be mixed the AIRMIX has extremely short mixing times and achieves a high, reproducible mixing accuracy. The AIRMIX can be easily integrated into existing plants due to its simple design. Provided a few preconditions are met, it is also possible, for instance, to retrofit existing silos with a mixing head in order to obtain an AIRMIX unit. The mixing effect is due to pneumatic fluidisation and air turbulence and is thus very gentle to the product. There is positively no unwanted comminution or heating of the product caused by shearing forces. As there are no moving mixing tools (such as rotors etc.), there can be no contamination of the product with lubricants, abraded particles etc., and the wear on the equipment itself is minimised. Its smooth surfaces and simple shape allow the entire mixer to be easily cleaned with air when the vessel is empty. This is also why only negligible quantities of product are carried from one batch to the next.
Typical Applications
The AIRMIX is used in the food processing industry, the chemical industry, the building materials industry and the metalworking industry, in particular when large volumes of dry bulk materials need to be mixed gently and quickly. In these industries the AIRMIX is used for homogenising, mixing and standardising special blends (such as pigments, methyl cellulose, plastic granules, starch, aluminium oxide, pharmaceutical products).
Limits of Application
The AIRMIX is suitable for all dry, fluidisable bulk materials up to a maximum particle size of approx. 3 mm. The maximum product feed temperature should not exceed 100°C. Economical batch sizes range from some 0.5 to 125 m³, depending on the product.
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