Filtration centrifuges typically apply the earth acceleration to discharge the cake downwards after the diverse process steps in the centrifugal field. This is valid for centrifuges with horizontal and with vertical axis. A peeler knife will transfer the cake to a moist powder, which will be conveyed out of the basket. Leaving the basket this powder will fall down to the next process equipment as a dryer or some type of packaging device, like bins or drums. To allow such a gravity powder transfer system, quite substantial pipe diameters are required to avoid blockage of this system.
The biggest disadvantage of the existing technology is that the transportation path from the centrifuge to the dryer is quite sensitive to crust formation and even blocking because an effective transportation force is missing. Often operators must manually interfere and remove product deposits, either inside of the centrifuge or in the downpipe to the dryer or at the inlet valve of the dryer.
In case of discrete batches, the amount of product which is forming the deposits is lost product, which must be removed by dissolving or flushing down by a cleaning in place ( CIP ) procedure before starting the next batch. If the product is very valuable and especially if the batches or campaigns are small, this amount of product might represent an important loss of yield and profit.
In total, the amount of residual product within the centrifuge is typically around 5% of the basket volume. The amount of residual product in the gravity powder transfer system is significantly more, even up to 20% of the basket volume.
ANDRITZ has developed and patented a new peeling and conveying system, which is not requiring any gravity discharge...
Session: L11 - Centrifugal Cake Filtration
Day: 23 October 2019
Time: 16:45 - 18:00 h