Basic Principle
The centrifuge uses the difference in specific gravity between solid and liquid to generate a strong centrifugal field through rotation, which can be magnified thousands of times. Under the action of centrifugal force, solid particles are settled on the drum wall of the centrifuge, thus achieving solid-liquid separation.
Specific process
1. Feeding: The suspension is added to the drum of the centrifuge.
2. Formation of annular liquid layer: The suspension forms an annular liquid layer under the action of centrifugal force, and the solid particles in it settle on the drum wall to form sediment.
3. Liquid discharge: The clarified liquid is discharged through the overflow port or suction pipe of the drum. This part of the liquid is called separation liquid.
4. Solid discharge: As the separation process proceeds, the sediment on the drum wall gradually thickens. When the clarity of the separation liquid does not meet the requirements, the feeding can be stopped or the sediment can be discharged manually or mechanically (such as a scraper for deceleration). For fluid sediment, it can also be discharged with a suction pipe at high speed.
Influencing factors
1. Solid-liquid phase density difference: The greater the solid-liquid phase density difference, the better the separation effect. For difficult-to-separate suspensions with small solid-liquid phase density difference, small solid particles or high liquid viscosity, a sedimentation centrifuge with a high separation factor should be selected, and the time the suspension stays in the drum should be extended (for example, reducing the feed amount or using a long drum, etc.) to ensure the clarity of the separated liquid.
2. Solid particle size: The larger the solid particles, the easier it is to settle on the drum wall. However, it should be noted that when the feed amount is too large, the fine particles flowing with the liquid may be discharged from the drum with the separated liquid before settling to the drum wall, resulting in turbidity of the separated liquid.
3. Drum structure and speed: The structure of the drum (such as conical, cylindrical or conical-cylinder combination) and the speed will also affect the separation effect. Generally speaking, the larger the diameter and length of the drum, the better the separation effect: but too high a speed may cause solid particles to be thrown out of the drum or destroy the liquid structure.
Application fields
The sedimentation centrifuge has a wide range of uses, especially for separation of suspensions when solid particles easily clog the filter medium and the filtration resistance is too large or when too many fine particles are lost during centrifugal filtration. In addition, it can also be used for separation of suspended liquids such as crystals, chemical precipitates, coal powder, dehydration of various sewage sludges, and slag removal and clarification of animal and vegetable oils.
The centrifuge achieves solid-liquid separation through the centrifugal field generated by rotation. In practical applications, it is necessary to select the appropriate centrifuge model and operating parameters according to the characteristics of the suspension and the separation requirements.