Figure 6. Inverting Filter Centrifuge. (Courtesy of Heinkel Filtering Systems, Inc.)
Feed Mechanism. An open-ended pipe centered in the bowl allows feeding of the slurry 360° around the cloth. The Inverting Filter Centrifuge is horizontally mounted like the peeler, so g-force does not effect the distribution of the cake. In addition, bars connecting the front plate to the back plate of the bowl insert serve as a distribution mechanism. Slurry passing the bars is evenly dispersed providing for a uniform cake. As a result, out-of-balance conditions are minimized. A special cement foundation or vibration isolator normally required for centrifuges is not necessary. Without this vibration, a load cell can be used in lieu of cake detectors or "feelers" to monitor the cycle and prevent overfilling the bowl. A typical cycle is shown in Fig 7.
Multipurpose Applications. Cake thickness is varied, dependent upon the application. Thin cakes from finer particles or more amorphous, compressible materials versus thick cakes for hard, easy filling crystals.
Discharge time is less than one minute, and even cake distributions allow for higher filling, washing and dewatering speeds, thus the overall cycle is shorter. One can therefore "efficiently" operate with a thin cake as low as 1/4", if necessary, as opposed to 3-6 inches on a conventional basket. If operating with a thin cake on a basket, the residual heel still exists and, as it requires sufficiently longer times for processing, it would be inefficient to operate with such a thin cake.
As a result of relatively thinner cakes and higher g-forces, filtration rates per unit filter cloth area can be as high as 20-30 times that of typical basket centrifuges. For that reason, a smaller volume Inverting Filter Centrifuge can replace a larger basket centrifuge. By optimizing based upon cake thickness (see Fig. 8.), higher productivities will be reached.
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