Principle of Centrifugal Purifiers
Consider gravity separation, as occurs in a settling tank, over a gradual period solids such as sludge, dirt, etc., will settle out at the bottom of the tank. The heavy liquids, such as water, will settle out above the solids and the lighter liquids, such as oil, will be at the top of the tank. The application of heat will speed up the separation process.
Separation occurs due to he specific gravities or densities of the liquids and solids.
In the above case it is gravity that is responsible for the settling out and this takes quite a while. If the gravitational force is increased, by using centrifugal force, the separation effect is much greater. This is shown in figure below by imagining settling tank on its side and rotated.
The centrifugal separator consists of a bowl containing a set of discs stacked one on top of the other. The dirty oil flows down the distributor and up through the holes in the discs.
"Operation and Maintenance of Machinery in Motor Ships" by N.E. Chell