Scroll decanter

Typical uses. Relatively coarse deliquoring and clarification of suspensions. FDSprocess ratings. 4 C, 3, 4, 3. 

Typical particle size and feed concentration range 1-5000 pm and 4-40% w/w. 

When finer particles are being processed the flow properties of the thickened solids can be poor and this leads to high helical screw torques and associated mechanical difficulties. Wear problems on the screw can also be caused by more abrasive particles. Scroll decanters can be adapted for use with toxic, flammable and volatile substances and there is some scope to perform (relatively poor) washing. 

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Theoretical studies (30) comparing the ability to dewater compressible solids by sedimenting and filtering centrifuges to pressure filters, have shown that at high G levels, scroll decanters produce drier cakes than pressure filtration. 

Scroll/decanter Continuous 5-50,000 200 1. Continuous solid discharge 2. High-feed solid concentration 1. Turbulence created by scroll 2. Low centrifugal force Antibiotic production... 

Solid bowl scroll decanter centrifuges have also been built vertically. The pendulum-type construction allows the bowl to expand more easily when operating at higher temperatures and makes mechanical sealing for elevated pressures less cumbersome. Although these units have been designed for operation up to 10 bars, they often operate at 5 bars or less. 

Figure 1.14 Schematic diagram of a horizontal axis scroll decanter centrifuge. The motor drive for the bowl and the gearbox required to produce the differential rotation speed between the bowl and screw conveyor are omitted for clarity.

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