In ancient China, people used one end of the rope to tie the pottery pot, held the other end of the rope, and twirled the pottery pot to produce centrifugal force to squeeze the honey out of the pottery pot. This was the early application of the principle of centrifugal separation.

Industrial centrifuges were born in Europe. For example, in the middle of the 19th century, three-legged centrifuges for textile dehydration and upper suspension centrifuges for separating crystalline sugar in sugar factories appeared. These earliest centrifuges were operated intermittently and discharged manually.

Due to the improvement of the slag discharge mechanism, continuous operation centrifuges appeared in the 1930s, and intermittent operation centrifuges have also been developed due to the realization of automatic control.

According to the structure and separation requirements, industrial centrifuges can be divided into filter centrifuges, sedimentation centrifuges and separators.

The centrifuge has a cylinder that rotates at high speed around its own axis, called a rotating drum, and is usually driven by an electric motor. After the suspension (or emulsion) is added to the drum, it is quickly driven to rotate at the same speed as the drum, and the components are separated under the action of centrifugal force and discharged separately. Generally, the higher the drum speed, the better the separation effect.

The working principle of the centrifugal separator includes centrifugal filtration and centrifugal sedimentation. Centrifugal filtration is the centrifugal pressure generated by the suspension under the centrifugal force field, acting on the filter medium, so that the liquid passes through the filter medium to become a filtrate, and the solid particles are trapped on the surface of the filter medium, thereby achieving liquid-solid separation; centrifugal sedimentation is to use The principle that each component with different density of suspension (or emulsion) settles rapidly in the centrifugal force field to achieve liquid-solid (or liquid-liquid) separation.

There is also a type of separator for experimental analysis, which can be used for liquid clarification and solid particle enrichment, or liquid-liquid separation. This type of separator has different structural types that operate under normal pressure, vacuum, and freezing conditions.

The important index to measure the separation performance of the centrifugal separator is the separation factor. It represents the ratio of the centrifugal force to the gravity of the separated material in the drum and its gravity. The larger the separation factor, the faster the separation and the better the separation effect. The separation factor for industrial centrifugal separators is generally 100 to 20,000, the separation factor for super-speed tubular separators can be as high as 62,000, and the separation factor for analytical super-speed separators can be as high as 610,000. Another factor that determines the processing capacity of the centrifugal separator is the working area of ​​the drum, which has a large processing area and a large processing capacity.

Filter centrifuges and sedimentation centrifuges mainly rely on increasing the diameter of the drum to enlarge the working surface on the circumference of the drum; in addition to the circumferential wall of the drum, the separator has additional working surfaces, such as the disc and chamber type of the disc separator The inner cylinder of the separator significantly increases the settlement working surface.

In addition, the more detailed the solid particles in the suspension are, the more difficult it is to separate, and the fine particles carried in the filtrate or the separation liquid will increase. In this case, the centrifugal separator needs a higher separation factor to effectively separate; in the suspension When the viscosity of the liquid is large, the separation speed slows down; the density difference of each component of the suspension or emulsion is large, which is beneficial to the centrifugal sedimentation, and the centrifugal filtration of the suspension does not require the density difference of each component.

The choice of centrifugal separator must be based on the size and concentration of solid particles in the suspension (or emulsion), the density difference between the solid and the liquid (or two liquids), the viscosity of the liquid, the characteristics of the filter residue (or sediment), and the separation requirements After comprehensive analysis, to meet the requirements of the moisture content of the filter residue (sediment) and the clarity of the filtrate (separation solution), initially choose which type of centrifugal separator. Then determine the type and specifications of the centrifuge according to the processing capacity and the automation requirements for the operation, and finally verified by actual tests.

In general, for suspensions containing particles with a particle size greater than 0.01 mm, a filter centrifuge can be used; for particles with small or compressible deformation in the suspension, a sedimentation centrifuge should be used; for suspensions with low solids content, small particles and When the liquid clarity is high, the separator should be used.

The future development trend of centrifugal separators will be to strengthen the separation performance, develop large-scale centrifugal separators, improve the slag discharge mechanism, add special and combined drum centrifuges, strengthen the separation theory research and study the optimization control technology of the centrifugal separation process.

Strengthening the separation performance includes increasing the rotating speed of the drum; adding a new driving force during the centrifugal separation; accelerating the speed of pushing the slag; increasing the length of the drum to prolong the time of centrifugal sedimentation and separation. The development of large-scale centrifugal separators is mainly to increase the diameter of the drum and use double-sided drums to improve the processing capacity so that the equipment investment, energy consumption and maintenance costs for processing unit volume of materials are reduced. In terms of theoretical research, it mainly studies the fluid flow conditions and filter residue formation mechanism in the drum, and studies the calculation methods of minimum resolution and processing capacity.