Specifications

Document No. DER04098 OPERATING INSTRUCTIONS
Page 14 of 19 Effective Date 06 Jun 08
OPERATION (CONT’D)
The following parameters affect centrifuge operation:
• Feed rate
• Pond depth
• Bowl speed
• Conveyor speed
Adjustment of one parameter may produce the desired clarity of liquid effluent and solids dryness.
Or the desired performance may be achieved by further adjustment. It is important to understand
the interdependence of the operating parameters. Changing one characteristic results in other
effects that may warrant additional adjustments.
Except for pond depth, these parameters can be adjusted while the centrifuge is operating. The
operator may then view the results of one change before making additional adjustments. The
following paragraphs describe the effect of changing each parameter.
Feed Rate
If slurry is low in viscosity and density, increasing the feed rate may permit a higher processing
rate. However, as feed rate is increased, residence time in the bowl is decreased, resulting in
more solids in the liquid discharge. Also, conveyor torque may rise indicating that the conveyor is
becoming burdened by moving the increased solids volume at its present speed. To reduce the
conveyor torque, the bowl speed may be lowered, the feed rate may be reduced, or the conveyor
speed may be increased to move the solids out faster. The feed rate setting and actual feed rate
are shown on the control panel to assist the operator in making adjustments.
Bowl Speed
The faster the bowl speed, the faster solids are settled through the pond to the outer wall of the
bowl and conveyed out of the centrifuge, but faster processing results in wetter solids discharge.
To reduce wetness, the slurry must remain in the bowl longer, subjecting it to the settling process
for a longer duration before being conveyed out the solids discharge. Conversely, reducing bowl
speed may be desirable for thick, heavy slurry to extract only high-density materials or larger
particles.
Both the bowl speed setting and actual bowl speed are shown on the control panel. The torque
percentage of the bowl is also displayed. This information is useful in optimizing bowl speed to
produce the desired solids dryness and processing speed.
Conveyor Differential Speed
With correct wiring polarity, the conveyor responds correctly to control system commands.
Changing the conveyor differential speed adjusts the solids discharge rate. Generally, a slower
differential speed will produce drier solids but reduces the solids discharge rate. Increasing
conveyor speed reduces drying time, leading to wetter discharged solids. Reducing conveyor
speed results in drier solids discharge. However, excessively slow conveyor speed permits solids
to accumulate in the bowl, possibly causing an overload condition.
The drying time is reduced by increasing the conveyor differential speed, which will increase the
wetness of the solids. Reducing the conveyor differential speed raises the settling time, which will
produce drier solids.