Gravity separation (such as in a settling tank) causes solids such as
sludge and dirt to settle at the bottom of the tank. Heavier 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 the differences in specific gravities (density) of
the liquids and solids. Heavier denser materials settle at the bottom,
lighter less dense materials at the top.
As mentioned, gravity is responsible for the separating 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. Imagine a settling tank on its side and rotated.
The high speed vertical 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.
After separation of the water and particles you must remove them from the
machine. Water is easy as it can flow to waste. There are two types of
machines for the sludge waste. Self cleaning centrifugal purifiers and
manual cleaning centrifugal purifiers. The manual cleaning purifiers
require periodic stop - open - clean. The self cleaning purifiers cycle
through a cleaning process.