| 摘要 |
This invention relates to an air classifier for the separation of granular material into three fractions, whereby each individual fraction is very precisely separated in a single housing. The classifier incorporates motor-driven separator/classifying wheels each of which is provided with a tangential separating-air supply at the level of the respective wheel, a fixed guide vane ring positioned at a radial distance from the circumference of the respective separating wheel, and at least one bulk-product feeder system as well as discharge provisions for fine, intermediate and coarse material, respectively. The wheels are provided with a closed cover disk at their respective first axial end and with fine and, respectively, medium fraction discharge port at their respective second axial end. The closed cover disks of the wheels form a free-flow gap in the space between the two stages of the classifier. An outward flow of air at the level of the upper and lower areas of the gap and an inward flow of air at the level of the center of the gap combine to produce a rotating eddy current or vortex in the separating zone. The vortex causes an extended dwell time of the dispersed bulk material particles in the transition zones of the two separating stages.
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