Differential speed is the difference between the bowl speed and the conveyor speed. The differential is provided by the gearbox which transmits power from the bowl to the conveyor. This is required in order to transport the solid particles that collect on the bowl inner diameter using conveyor. The differential speed determines how long the solid particles remain in the bowl.

The differential speed is decisive for the time that the solid particles remain in the decanter centrifuge, and the compression that it undergoes. It is important and necessary to be able to set the differential speed variably, because changing drilling mud properties in the feed lead to differing conditions, and thus it is possible to keep the total dry solids of the solid at an optimum level. Many centrifuge manufacturers provide a “back drive” which can independently alter the speed. Back drive units are, in effect, hydraulic gear reduction systems used to vary the speed of the conveyor relative to the bowl.

Differential speed adjustment and its advantages

• The differential speed makes it possible to keep the solids in the decanter bowl for the ideal length of time
• Optimum dewatering with fluctuating feed conditions
• Optimum setting of the total dry solids that can be achieved
• Protection against overload and blockage
• Variably adjustable differential speed can make it possible to do the treatment of an extremely wide range of drilling mud