Working Principles of Disc Centrifuge

Disc centrifuge (separator) is one type of sedimentation centrifuge used for separating difficult-to-separate materials, such as suspensions composed of viscous liquids and fine solid particles or emulsions composed of liquids with similar densities. In addition to its powerful separation capabilities, disc centrifuges can facilitate continuous production, providing efficiency unmatched by ordinary centrifuges. Therefore, they find extensive applications in various industries, including mineral oil, dairy products, vegetable oil, beverage production, starch, pharmaceuticals, and chemical engineering. This article introduces the concept of disc separators and illustrates the principles of liquid-liquid and liquid-solid separation using multiple diagrams.

01 Concept:

The disc centrifuge is a vertical centrifuge with its drum mounted on the upper end of a vertical shaft. Driven by an electric motor through a transmission device, the drum rotates at high speed. Inside the drum, there is a set of stacked disc-shaped components (discs). The disc centrifuge utilizes the centrifugal force generated by high-speed rotation to achieve the separation of various immiscible materials with different densities. Currently, disc centrifuges are categorized as two-phase and three-phase separators.

02 Basic Principles:

Centrifugal separation, also known as centrifugation, is a method of achieving liquid-liquid and liquid-solid separation in non-uniform liquid systems by utilizing centrifugal force. The disc centrifuge can be used for both liquid-solid and liquid-liquid separation.

  • Liquid-Solid Separation: In liquid-solid separation, the suspension enters the drum through the central feed pipe, flows from the outer edge of the disc stack through the gaps between the discs toward the inner edge. As the untreated liquid enters the high-speed rotating gaps between the discs, inertia centrifugal force is generated. Solid particles with higher density move toward the lower surface of the upper disc under the action of centrifugal force, then slide down along the lower surface toward the rotor's periphery, while the liquid rises toward the rotor's center and is discharged from the casing, achieving separation.
  • Liquid-Liquid Separation: For liquid-liquid separation, the emulsion enters the gaps between the discs through the feed holes in the disc stack. It is separated into heavy liquid and light liquid based on different densities. The heavy liquid flows along the inner surface of the disc toward the drum wall, while the light liquid flows toward the center. They are respectively discharged through overflow ports and a centrifugal pump.
  • Position of the Density Ring: To achieve better separation effects in the centrifuge drum, it is crucial to clearly distinguish between different densities of heavy and light phases in the liquid mixture. The density ring, as a vital component controlling the water discharge within the drum, plays a crucial role in the effectiveness of oil-water separation. Therefore, the appropriate density ring should be selected for the drum based on the density of the separation medium.
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