Basic Structure and Principles of Horizontal Decanter Centrifuge

The horizontal decanter centrifuge, also known as a horizontal spiral centrifuge, is a settling device that operates continuously and unloads using a screw. In general, it features a compact structure, continuous operation, smooth running, strong adaptability, large production capacity, easy maintenance, and excellent dewatering effects. Therefore, its applications in the field of environmental protection are becoming increasingly widespread.

Although different manufacturers may have different equipment structures, materials, specifications, and operating adjustment mechanisms for horizontal decanter centrifuges of different specifications or models, their basic equipment principles are similar. Taking the widely-used Alfa Laval equipment as an example, let's provide a simple introduction to facilitate better use and adjustment for on-site users.

Working Principle of Horizontal Decanter Centrifuge

The horizontal decanter centrifuge mainly consists of a drum, screw, differential, etc. The drum rotates at high speed, and the screw rotates in the same direction but at a slightly lower speed. The structure of the horizontal decanter centrifuge is as follows:

  • Drum: Achieves ideal settlement separation through high-speed rotation.
  • Screw: Conveys and compacts sludge.
  • Differential: Generates speed difference between the drum and screw.
  • Clear Liquid Outlet: Recovers liquid phase, i.e., clear liquid, through overflow.
  • Sludge Discharge Outlet: Recovers solid phase, i.e., sludge, through gravity.

The horizontal decanter centrifuge utilizes the difference in solid-liquid specific gravity and the action of centrifugal force to achieve solid-liquid separation. The working process is as follows:

  1. The continuous suspension flows into the drum through the feed pipe (hollow shaft), and it is immediately thrown into the drum chamber. The high-speed rotation of the drum generates a strong centrifugal force. Solid particles (sludge) adhere to the inner wall of the drum due to the centrifugal force and continuously accumulate, forming a solid layer in a ring shape, also known as the solid ring layer.
  2. Water in the liquid phase also forms a liquid layer due to the action of centrifugal force, but because its density is lower than that of solid particles, the centrifugal force acting on it is smaller than that on solid particles. It is located on the inner side of the solid ring layer and is called the liquid ring layer.
  3. Utilizing the relative movement generated by the speed difference between the drum and the screw, the solid ring layer is pushed to the conical end of the drum. Sludge continuously discharges from the discharge outlet at the cone end. The liquid ring layer turns to the large end of the drum, and an overflow port is distributed at the large end. Liquid overflows from the overflow port, and the separated liquid (clear liquid) is discharged through the liquid discharge port.
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