Difference between solid-liquid & solid-liquid–liquid separation by decanter centrifuge

In the processing and selection of decanter centrifuge, it is sometimes necessary to judge whether solid-liquid two-phase separation can be completed in case of accident due to the difference of properties of materials to be separated, or whether liquid can be divided into light liquid and heavy liquid needs solid-liquid three-phase separation. This delineates the need for solid-liquid separation using two-phase separation or solid-liquid-liquid three-phase separation of decanter centrifuges.

The two-phase decanter centrifuge consists of frame, cover, main bearing, drum, screw, differential, drive system and control system. The drum and the screw rotate at the same direction and high speed at different speeds. The material enters the inner cylinder of the screw through the feed pipe and enters the drum from the feed port.

Under the action of centrifugal force, the heavy solid-phase materials are deposited on the wall of the drum to form a sediment layer, and the spiral continuously pushes the deposited solid-phase materials to the cone end of the drum, which is discharged out of the machine through the slag discharge port. The lighter liquid phase materials form an inner liquid ring, which overflows the drum continuously from the overflow port at the big end of the drum, and is discharged out of the machine through the discharge port.

The three-phase decanter centrifuge is mainly used for solid-liquid-liquid separation, that is, separation of one solid phase (high density) and two liquid phases with different densities. The drum and the screw rotate at the same direction and high speed at different speeds. The material enters the inner cylinder of the screw through the feed pipe and enters the drum from the feed port.

Under the action of centrifugal force, the solid phase material is deposited on the wall of the drum to form a sediment layer, and the two liquid phase materials form a light liquid phase ring and a heavy liquid phase ring respectively. From the wall of the drum, the solid phase layer, the heavy liquid phase layer and the light liquid phase layer are successively formed inward.

The solid materials deposited on the drum wall are continuously pushed to the cone end of the drum by the screw and discharged out of the machine through the slag discharge port. The light liquid phase and heavy liquid phase overflow continuously from different overflow ports at the big end of the drum, so as to realize three-phase separation.