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Operating Principle of Separator?

Liquid-liquid and liquid-solid mixtures can be separated in settling tanks y gravity or in centrifugal separators by centrifugal force, provided that the components of the feed liquid have different densities. Since the centrifugal force developed by centrifugal is many thousand times the force of gravity, separation by centrifuging is accomplished many thousand times faster than by natural settling and takes place in seconds.


Clarification Principle:
If a liquid-solid mixture is poured into a stationary vessel, the solid particles, bring heavier, will slowly sink to the bottom under the action of gravity. 

The larger the settling area and the shallower the vessel, the shorter will be the settling time required to achieve a certain degree of clarification for a specified volume of liquid. The greater the difference between the densities of the liquid and the solids, the more effective will be clarification.
In a rotating vessel, the solid particles subjected to centrifugal force, will deposit much faster than a stationary vessel. 


Purification Principle:
 
Settling tank with one feed inlet and two outlets which can be used for continuous separation of a liquid-liquid mixture with simultaneous removal of solids. The difference in height between the two overflows must be adjusted in accordance with the difference in density of the two liquid phases so as to achieve equal hydrostatic pressure, 

thus    ρ₁*h₁=ρ₂*h₂


Before separating, for instance, an oil-water mixture containing a preponderance of oil, the vessel must first be filled with water so as to form a water seal.

The throughput of a settling tank of this king id dependent on the retention time required for complete separation of the components of the feed liquid.

The settling vessel rotating about an axis is a separator bowl in its simplest form where separation takes place in the same way as in a stationary vessel. However, the centrifugal field in a rotating bowl is much more effective than the gravitational field of a stationary settling vessel since the liquid pressure increases with the square of the distance from the axis of rotation.
For the balance of the hydrostatic pressure in the rotating bowl the following formula applies: \
                          ρ₁(R²-r₁²)=ρ₂(R²-r₂²) 



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