Specifications

Document No. DER01122
Effective Date 30 Aug 07
Page No. 1 of 6
DESCRIPTION AND OPERATION
DE-7200 CENTRIFUGE
GENERAL
The centrifuge is a high-speed electro-mechanical machine using electronically controlled electric
motors to drive the bowl assembly and conveyor. The centrifuge receives slurry through a feed
component at the liquid discharge end of the machine. The slurry is dispersed into the rotating
bowl, where centrifugal force is employed to separate liquid from the solids. Liquid flows out the
liquid discharge chute, while solids are conveyed to the solids discharge chute at the gearbox end
of the machine.
The centrifuge is configured at the factory to operate on a specific three-phase, 50Hz or 60Hz AC
voltage. The specified power configuration must be supplied to the machine. The electronic
control panel is mounted on the separate control cabinet, which can be placed locally or remotely
from the centrifuge. Safety devices built into the centrifuge protect personnel and equipment by
shutting down the bowl and conveyor motors in case of excessive bowl or conveyor torque, high
main bearing temperature, vibration, overspeed, or other malfunction.
OPERATING PRINCIPALS
The centrifuge employs G forces produced by the high-speed rotation of a cylindrical bowl to
separate solids from a slurry. Centrifuge performance is based on three variable factors:
• G force exerted on the fluid - Gravitational force pulling fluid against the outside wall of the
centrifuge
• Retention time in the centrifuge - The longer the slurry remains in the centrifuge the smaller
the particle that can be separated
• Differential speed of conveyor - The faster the conveyor rotates, the wetter the solids and the
more solids that are discharged
All three factors may be manipulated in the Derrick DE-7200 centrifuge to alter the liquid and
solids discharge. The centrifugal force is adjusted by varying the bowl RPM. Retention time is
controlled by adjusting the liquid discharge ports on the liquid bowl head to vary the pond depth
(depth of liquid remaining in the bowl), and the feed rate to the unit (the lower the feed rate, the
higher the retention time). The conveyor operates at a slightly faster speed than the bowl. The
conveying speed is the difference between the bowl and conveyor speeds. During centrifuge
operation, the bowl and conveyor speeds are shown on the Operation screen.
Other than pond depth, all other parameters may be changed quickly and easily to adjust the
equipment for optimum efficiency in response to varying feed conditions. For best performance,
the slurry should be screened to 74 microns in vibrating screening machines before passing to the
centrifuge for processing.