A centrifugal separator has a cylinder that rotates at high speed around its own axis, called a rotating drum, and is usually driven by a 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 by centrifugal force and discharged separately. Generally speaking, the higher the drum speed, the better the separation effect.

The working principle of centrifugal separator includes centrifugal filtration and centrifugal precipitation;

① Centrifugal filtration: the centrifugal pressure generated by the suspension under the centrifugal force field acts on the filter medium (filter screen or filter cloth) to make the liquid pass through the filter medium to become filtrate; While solid particles are trapped on the surface of the filter medium to form filter residue, thus realizing liquid-solid separation. There are holes in the circumferential wall of the filter cartridge, and the inner wall is lined with filter media.

② Centrifugal sedimentation: Liquid-solid (or liquid-liquid) separation is realized by using the principle that components with different densities in suspension (or emulsion) quickly settle and stratify in centrifugal field. The circumferential wall of the settling drum has no holes. Figure 3 shows four typical settling tanks. After the suspension (or emulsion) is added to the drum, solid particles (or high-density liquid) settle on the wall of the drum to form sediment (or heavy separation liquid). The liquid with lower density gathers in the center of the drum, flows to the overflow port, and is discharged as separation liquid (or light separation liquid). Drum is intermittent slag discharge, which is suitable for the separation of suspension or emulsion with small particle size and low solid particle concentration; The drum in fig. 3b uses spiral continuous slag discharge to separate suspension with high solid particle concentration. In the rotating drum with multi-layer conical disks, the liquid is divided into several thin layers by the disks, which shortens the distance of sedimentation and separation, accelerates the separation and improves the separation effect.

Another separator for experimental analysis can be used for liquid clarification, solid particle enrichment or liquid-liquid separation, and the separation particle size can reach 0. 1 ~ 0.5 micron. The commonly used test tube separator (Figure 4) rotates at the speed of 3000 ~ 20000 rpm, and the glass test tube filled with the same amount of feed liquid is symmetrically inserted into the groove of the pendulum frame or angular rotor, and the feed liquid is settled and layered in the test tube under the action of centrifugal force. The separator used for ultra-high speed analysis adopts a small diameter settling drum. This separator has different structural types and can work under normal pressure, vacuum and freezing conditions.