Centrifuges have a high-speed rotating cylinder, called a bowl, around its axis, usually driven by an electric motor. After the suspension (or emulsion) is added to the drum, it is rapidly driven to rotate at the same speed as the drum, and the components are separated and discharged separately under the action of centrifugal force. In general, the higher the drum speed, the better the separation effect.
There are two types of centrifugal separators: centrifugal filtration and centrifugal sedimentation. 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), 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 residues, thereby Realize liquid-solid separation. There are holes on the circumferential wall of the filter drum, and the inner wall is lined with filter media. ②Centrifugal sedimentation: Liquid-solid (or liquid-liquid) separation is realized by utilizing the principle of rapid sedimentation and stratification of components with different densities of suspension (or emulsion) in the centrifugal force field. The peripheral wall of the sinking drum has no holes. After the suspension (or emulsion) is added to the drum, the solid particles (or liquid with higher density) settle to the drum wall to form a sediment (or heavy separation liquid). The liquid with lower density gathers toward the center of the drum, flows to the overflow port and discharges, and becomes the separation liquid (or light separation liquid). The drums are all intermittent slag discharge, which is suitable for the separation of suspensions or emulsions with small particle size and low concentration of solid particles; the rotary drum in Figure 3b uses spiral continuous slag discharge, which can separate suspensions with high solid particle concentration . In the drum with multi-layer conical discs, the liquid is divided into several thin layers by the discs, which shortens the distance of sedimentation separation, accelerates the separation, and improves the separation effect.
When the solid and liquid mixture to be separated enters the high-speed rotating drum from the feeding port, under the action of centrifugal force, the mixture is filtered through the filter screen, the liquid separation is discharged through the drain pipe, and the solid separation is left in the drum. Inside, when the solid separation in the drum reaches the requirements specified by the equipment, stop feeding, clean the solid separation, and discharge the washing liquid at the same time. After the cleaning meets the requirements, the centrifugal separator runs at a low speed, and the solid separator discharge device (scraper) is driven by the AC servo motor to discharge the solid separator to complete a working process.
