Friday, August 13, 2010

Multifrequency excitation increase efficiency in the vibration screening

In the process, there are many materials that can be due to their particle shape and / or surface properties are difficult to separate the classical screening machines. A mechanical transfer system that generates multi frequency oscillations, promises help.


In the novel separation processes of Kaiser Engineering is a mechanical adjustment system with multifrequency vibration adapters. The engine vibrates a screen, it produces oscillations that are transferred to the screen body of the machine. The screen body mounted on multifrequency adapter handles the vibrational energy of this, they converted from a one-in a multi-frequency, amplify them to the 200 - to 500-fold and finally transfers it to the screen. Here, the multifrequency excitation evenly across the screen surface by means of resonance ring (s) or transfer rods. Because of built-in buffer system filters do not get any high-frequency oscillations back to the screen body of the machine.

The special feature of this method is that it is purely mechanical work without additional external power supply.

Increase the throughput

In conventional vibration screening equipment all particles are under the influence of a single frequency produced by the engine. Consequently, the particles are distributed only on the screen surface. When using the multi-frequency method, however each individual particle is its own resonance frequency, since a wide range of frequencies is simultaneously available on the screening surface and the distribution of frequencies on the screen surface for more than ten changes per second. This "strong impulse to shoot through the entire thickness of the layer of material and cause a continuous mixing of the material. The result is that the material virtually at the screen surface "froth" is. This vibro-moving layer effect may be substantially greater thicknesses are processed as usual, like a practical example shows: A manufacturer of highly abrasive tungsten carbide could on a conventional screening a maximum throughput of 25 kg / (hm ²) reach. After switching to the multi-frequency method, the throughput performance of his investment increased to 560 kg / (hm ²).
Increase Efficiency



On a conventional screening machine to have lower grain belonging particles that are higher in the material bed, the less chance to reach the mesh, the farther away they were originally placed - from the screen surface from view -. They, together with the main load on the material transported and discharged through the oversize discharge. With the new process each particle moves according to its parabola under the influence of its own resonance frequency. This makes the distance between the particles wide open, so that almost all small particles that are able to pass through the mesh openings are not blocked by larger particles and reach the screen surface can.

Here again, two practical examples: a user who previously could not separate coal suspensions itself at 500 microns, achieved thanks to a novel separation procedure efficiency 70-94 percent for a cut point of 45 microns. A manufacturer of pet food that could not be realized in a conventional screening a cut point of 0.8 mm due to blockages, reached by using the new separation process with an aperture of 1.2 mm, a cut point of 0.8 mm with a 96 percent efficiency.
screen disturbance avoided

The new separation procedure is safe accelerations of up to 1000 G, while traditional screens can produce withstand accelerations of not more than ten to twelve, and G. At this level of G-force and because of the extremely strong stimulus that transmits the multi-frequency method from the bottom of the screen lining to the screenings, gets stuck no particles.

For example, a user reaches quartz sand with irregular particles through the use of novel separation procedure is not otherwise possible sieving at 100, 150 and 200. The throughput capacity 7-8 t / (hm ²) or here on what is normally realized on separating sections in the millimeter range.

Even with sticky materials, the sieve surface exceeds the energy supplied much of the force with which the material adheres to the screen surface. A user who previously could not dolomite with a moisture content of 2% below a cut point of 8 mm with a throughput capacity 4-5 t / (hm ²) seven, can be separated using the new process is now at a cut point of 2 mm with the same throughput and made themselves at 1 and 0.5 mm or throughput 2-3 t / (hm ²).

In a conventional screening, the agglomerate moves on the screen surface and is finally discharged via the oversize outlet. A further complication is that agglomerations tend to clog the mesh size, since they are relatively heavy and weak applied single frequency vibration in many cases they can move. By using the new method to break the one hand, strong impetus from the underside of screen lining to the agglomerates. On the other hand, all particles move inside the agglomerate separately because of the influence of its own resonance frequency, which leads to a deagglomeration.

A customer who initially in his trial of 70% lower grain and 30% oversize (Committee ran out), put down after a test sieve with the new multi-frequency method that nearly 100% of feed material through the mesh openings left. Moreover, it was clear that what was previously considered by the customer as oversize constituted, in fact agglomerates.
Summary and Outlook

The separation procedure presented here is a first sieve element available, the linear instead of the screen body in the screening surface while not excited, not harmonious and multifrequent form. This significant improvements and wider applications to achieve the vibrating screen technology, particularly in fine screening down to 23 microns and difficult to screen materials. Sometimes it is even possible to replace other processes such as hydro-cyclones or air classifier.

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