The separation principle of the centrifuge is mainly based on the centrifugal force, which is used to separate liquids from solid particles or liquids of different densities through the centrifugal force generated by high-speed rotation. Specifically, the separation principle of the centrifuge can be summarized as follows:
Generation of centrifugal force
Inside the centrifuge is a cylinder that rotates at high speed around its own axis, called a drum, which is usually driven by an electric motor. When the drum rotates at high speed, the suspension (or emulsion) is quickly driven to rotate at the same speed as the drum.
In this process, the material particles are acted upon by the centripetal force, but due to the rotation of the drum, these particles actually feel an outward centrifugal force, which is much greater than gravity, so rapid separation can be achieved.
Separation method
There are two main types of separation principles of centrifuges: centrifugal filtration and centrifugal sedimentation.
Centrifugal filtration: The centrifugal pressure generated by the suspension under the centrifugal field acts on the filter medium (such as a filter screen or filter cloth), so that the liquid passes through the filter medium to become filtrate, while the solid particles are trapped on the surface of the filter medium to form filter residue, thereby achieving liquid-solid separation. There are holes on the circumferential wall of the filter drum, and the inner wall is lined with filter medium.
Centrifugal sedimentation: The principle of rapid sedimentation and stratification of components with different densities of the suspension (or emulsion) in the centrifugal field is used to achieve liquid-solid (or liquid-liquid) separation. The circumferential wall of the sedimentation drum is hole-free. Solid particles (or liquid with higher density) settle to the drum wall to form sediment (or heavy separation liquid); liquid with lower density gathers toward the center of the drum, flows to the overflow port and is discharged to become separation liquid (or light separation liquid).
Factors affecting separation effect
Speed: The higher the drum speed, the greater the centrifugal force generated and the better the separation effect. However, it should be noted that too high a speed may increase equipment wear and energy consumption.
Separation factor (Fr): It is an important indicator to measure the separation performance of a centrifuge, indicating the ratio of the centrifugal force exerted on the separated material in the drum to its gravity. The larger the separation factor, the faster the separation is usually and the better the separation effect.
Working area: The larger the working area of the drum, the greater the processing capacity. Filter centrifuges and sedimentation centrifuges mainly rely on increasing the drum diameter to expand the working surface on the drum circumference; while some centrifuges (such as disc separators) significantly increase the sedimentation working surface by adding working surfaces (such as discs and inner cylinders).
Application fields
Centrifuges are widely used in many fields such as chemical industry, petroleum, food, pharmaceutical, mineral processing, coal, water treatment and shipping. It can efficiently process various suspensions and emulsions, realize solid-liquid separation or liquid-liquid separation, and provide important support for the production of related industries.
In summary, the separation principle of the centrifuge is to separate liquids and solid particles or liquids of different densities through the centrifugal force generated by high-speed rotation. Its separation effect is affected by many factors such as rotation speed, separation factor and working area.