The differential speed for decanter centrifuge used in drilling waste management depends on the feeding slurry conditions.
1) What is decanter centrifuge differential Speed?
The bowl and the screw conveyor inside the bowl runs at the same direction, but slower than centrifuge bowl speed. That’s the reason why the screw conveyor will push solids out of the decanter centrifuge. The differential speed is the how much RPM the screw conveyor slower than the bowl speed. For oil gas industry, normally the operator runs the decanter centrifuge with differential speed from 10- 50 RPM. The more RPM differential speed, the faster the screw push the solids, so the more capacity the centrifuge can handle, but the more moisture solids will be discharged, and vice versa. The formula is as below.
2) How to calculate decanter centrifuge differential Speed
Differential Speed= ( Bowl Speed – Gearbox Input speed) / Gearbox ration
- Gearbox Input speed means the gearbox pulley speed.
- Gearbox ration= 57 for GNLW363 Series.
- Gearbox Input speed is the back drive motor speed transferred from the belt to the gearbox depends on the pulley on the gearbox side and back drive motor side.
So for example, if the decanter centrifuge bowl speed =3200RPM and Gearbox input speed=1468RPM, then we can calculate
(2)Now operator wants to separate high gravity solids in the drilling waste so, he can adjust the decanter centrifuge bowl speed to be 2500RPM and ,if they do not adjust the back drive motor speed, the Differential speed=(2500-1468)/57= 18RPM
And if in this case, the operator wants to increase the capacity of the decanter centrifuge ,he can lower down the back drive motor speed from 60HZ to 30 HZ so gearbox input speed will change from 1468to 734RPM and decanter centrifuge differential speed=(2500-734)/57= 30RPM
Normally the customer can set 30RPM differential speed to check the performance and adjust the back drive motor speed to get the suitable differential speed for different mud.