In evaporation crystallization systems, centrifuges are commonly used salt separation equipment. Centrifuges are machines that use inertial centrifugal force to separate liquid non-homogeneous mixtures. According to the separation method, centrifuges can be divided into filter centrifuges and sedimentation centrifuges. Filter centrifuges can be divided into tripod centrifuges, top-hung centrifuges, horizontal scraper discharge centrifuges (including siphon scraper discharge centrifuges), horizontal piston discharge centrifuges, centrifugal discharge centrifuges, and screw discharge filter centrifuges, etc. Sedimentation centrifuges can be divided into screw discharge sedimentation centrifuges, butterfly separators, tubular separators, and chamber separators, etc. In evaporation crystallization systems, the main type used is the filter centrifuge. This article will detail the principle and selection points of the tripod centrifuge.

The tripod centrifuge is the most widely used and adaptable equipment among filter centrifuges. It can be used to separate particles with a particle size of 10μm to several millimeters, as well as fibrous or blocky materials. It can work well within a solid content range of 5% to 60% in the suspension. Moreover, it is adaptable to changes in material concentration and material filtration performance, and the filter cake is easy to wash, with the washing time and washing water volume easily adjustable. The disadvantage of the tripod centrifuge is that the labor intensity of workers is high, and the equipment production efficiency is low, generally only suitable for small-scale production. The separation factor of the tripod centrifuge is 500-1000, and the drum diameter is 300-2000mm.

The high-speed rotating drum is suspended on three support columns of the machine base and driven by a rigid shaft main shaft. The main shaft and its support, drive, and other devices are installed on the chassis of the machine, making the entire unit in a flexible support state.

In the drum, solid particles in the suspension move towards the drum wall under the action of centrifugal force. Affected by the interception of the filter medium, a filter cake is formed and accumulated on the inner wall of the drum. Under the action of centrifugal force, the liquid passes through the filter cake and leaves the drum through the small holes in the drum, realizing the separation of the liquid and solid phases. When the filter cake reaches a certain thickness, feeding is stopped, and dehydration occurs. At this time, washing liquid is added to wash the filter cake, then dried, and the machine is stopped. The filter cake is manually unloaded from the top.

When the separated liquid-solid two-phase suspension has a low solid content and the solid particles are very fine, making it difficult to use a filter centrifuge, a sedimentation tripod centrifuge can also be used. The difference in structure from the tripod filter centrifuge is that there are no holes on the drum wall, no filter medium is used, and a liquid skimming device is added. The material is added to the high-speed rotating drum, and under the action of centrifugal force, the solid particles move towards the drum wall and accumulate into slag, and the liquid phase gradually becomes clear. After a period of sedimentation separation, the liquid can be discharged from the machine by means of the radial movement of the skimming pipe using tangential velocity. When the solid accumulation layer in the drum reaches a certain thickness, the machine is stopped, and the sediment is removed manually.

According to the different unloading methods, tripod centrifuges can be divided into two categories: manual unloading and mechanical unloading. Manual unloading tripod centrifuges are intermittent operations, with high labor intensity for workers and low equipment production efficiency, but they are highly adaptable to materials and easily maintain the integrity of product crystals. Mechanical unloading is mainly suitable for filter cakes with relatively loose crystalline solid particles, which have a certain destructive effect on the crystals. However, the labor intensity of workers is low, and program or automatic control is easily achieved.

Unloading and Operating Methods of Tripod Centrifuges:

The speed of a tripod centrifuge varies in different operating stages. Generally, materials are added at a speed of 200-800 r/min, separation is performed at a speed of 1000-1600 r/min, and scraper unloading is performed at a speed of 20-100 r/min (manual unloading tripod centrifuges need to be unloaded when stopped). Therefore, the drive device is required to achieve a wide range of speed changes. Currently, the speed change methods of tripod centrifuges are as follows.

Selection of three-legged centrifuge models

The selection of three-legged centrifuges generally follows the following principles:

Except for sedimentation-type three-legged centrifuges, which do not need to use filter media, all other types of three-legged centrifuges need to use filter media to capture solid particles. Commonly used filter media include filter cloth or metal mesh. The selection principles of filter media are as follows:

Scan the code to follow the "Hezhong Environment" video account