Specifications

Document No. DER01120 DESCRIPTION AND OPERATION
Page 2 of 9 Effective Date 25 May 07
OPERATING PRINCIPALS (CONT’D)
During centrifuge operation, slurry is pumped through the feed tube into the center of the rotating
conveyor (Figure 1120-1), where it splashes against the feed accelerator. The high velocity slurry
is then dispersed out four feed nozzles mounted in the periphery of the conveyor cylinder.
Rotating at a higher speed than the conveyor, the bowl creates an additional shearing effect,
which further increases the slurry’s acceleration. The depth of the slurry in the bowl (pond depth)
is determined by the setting of weirs on the liquid bowl head (large end of the bowl).
As the slurry flows in the channels between the conveyor flights, the heavy particles settle at an
accelerated rate due to the G force imposed by the rotating bowl. Sand particles settle almost
instantly; then the finer, lighter particles settle. Particles that cannot be settled under the present
centrifuge settings will be discharged with the liquid through the adjustable weirs on the liquid
bowl head. Liquid exiting the liquid bowl head is directed through the liquid discharge outlet.
The settled solids form a cake on the inside of the bowl and are transported by the conveyor
toward the narrow end of the bowl, or beach. As the solids travel across the beach, their free
liquid film is lost due to centrifugal squeezing and drainage. When they are discharged at high
velocity through the solids discharge ports on the bowl, they contain only the adsorbed moisture.
Since the discharge cake is very heavy and sticky because of the lack of free liquid, the centrifuge
should be installed over the receptacle that is to receive the discharged solids. If this is not
possible a slide or chute is needed to convey the solids. At least a 45-degree angle is required to
ensure self cleaning, or a wash system must be provided to prevent material buildup.
Figure 1120-1 Centrifuge Operation