Specifications

Document No. DER01120
Effective Date 25 May 07
Page No. 1 of 9
DESCRIPTION AND OPERATION
DE-1000 CENTRIFUGE - GEARBOX DRIVE
GENERAL
The centrifuge is a high-speed electro-mechanical machine using a 50 HP electric motor to drive
the bowl assembly and conveyor. The centrifuge receives slurry through a feed tube at the pulley
end (solids discharge) 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 Victaulic
®
connection at the gearbox end of the centrifuge, while solids are conveyed to
the solids discharge located at the pulley end of the machine. The solids fall into a chute at the
bottom of the machine.
The centrifuge is configured at the factory to operate on a specific AC voltage supplied in three-
phase, 50Hz or 60Hz. The specified power configuration must be supplied to the machine.
Electrical controls are mounted on the electrical control box located at the machine’s liquid
discharge end. Safety devices built into the centrifuge protect personnel and equipment by
shutting down the drive motor in case of excessive conveyor pressure, high motor temperature,
vibration, 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-1000 GBD centrifuge to alter the liquid
and solids discharge. The G force is adjusted by changing the motor sheave to vary 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 conveyor differential speed
may be altered by changing gearbox ratio. The conveyor operates at a lower speed than the bowl;
its speed is derived from the gearbox ratio. The conveying speed is the difference between the
bowl and conveyor speeds.
Beyond centrifuge modifications or adjustment, the feed rate may be varied. Changing the feed
rate provides an additional means of altering the discharge results. Adjusting any parameter—
pond depth, bowl speed, and conveyor differential speed—requires shutdown of the equipment.
For best performance, the slurry should be screened to 74 microns in vibrating screening
machines before passing it to the centrifuge.