ALLWEILER The horizontal spiral centrifuge is horizontal in structure, which is a kind of settlement equipment that can be operated continuously and discharge materials with screws. It belongs to the spiral discharge settlement centrifuge, which is called horizontal spiral centrifuge for short.

Generally speaking, the horizontal screw centrifuge has the characteristics of compact structure, continuous operation, relatively stable operation and strong adaptability. It has large production capacity, convenient repair and good dehydration effect. Therefore, it is increasingly used in the field of environmental protection.

Although the horizontal snails of different standards or models from different manufacturers have different equipment structures, equipment raw materials, standards and operation adjustment mechanisms, their basic equipment principles are similar, so I will take Alfa Laval equipment, which is widely used in the industry, as an example to give you a brief introduction, so as to facilitate better use and adjustment of on-site users.

Operation principle of horizontal spiral centrifuge

    ALL WEILER horizontal spiral centrifuge is mainly composed of drum, screw, differential, etc. The drum rolls at a high speed. The spiral and drum roll in the same direction but at a slightly lower speed.

The horizontal spiral centrifuge uses the solid-liquid specific gravity difference and centrifugal force effect to complete solid-liquid separation. Its operation process is as follows:

The suspension continuously enters the drum through the feed pipe (hollow shaft), and then is thrown into the drum cavity. The drum rolls at a high speed with a very strong centrifugal force. Solid particles (sludge) stick to the inner wall of the drum due to the centrifugal force effect, and continue to accumulate. The solid layer formed is a ring, also known as the solid ring layer;  

The liquid phase water also forms a liquid layer due to the effect of centrifugal force, but because its density is less than that of solid particles, the centrifugal force effect it receives is also less than that of solid particles. It is located inside the solid ring layer, which is called the liquid ring layer.  

Using the relative movement between the rotary drum and the spiral speed difference, the solid ring layer is pushed to the cone end of the rotary drum, and the sludge is continuously discharged from the slag discharge opening scattered at the cone end; The liquid ring layer is transferred to the big end of the drum. Overflow ports are scattered at the big end of the drum. Liquid overflows the drum from the overflow port and is discharged through the drain port to form separated liquid (i.e. clear liquid).

Factors influencing separation effect of horizontal spiral centrifuge

To understand the separation effect of horizontal spiral centrifuge, we should first understand its effect principle, and then we can effectively control it in use.

Rotating speed of centrifuge drum

The adjustment of drum speed is usually completed by frequency conversion motor or hydraulic motor. The improvement of rotating speed of the drum will improve the separation effect. The higher the rotating speed is, the greater the centrifugal force is, which is helpful to improve the solid content of mud cake.

The speed difference between screw and drum is added to increase the treatment capacity, but too fast speed will damage the sludge floc, and reduce the dewatering effect. The higher the rotational speed, the higher the solid dryness is not necessarily.

In addition, higher rotating speed will cause machine oscillation, increase the wear of the machine, and increase the power consumption, oscillation and level accordingly, reducing the service life of the equipment.

Therefore, the rotation speed should be reasonably selected to meet the separation requirements.

Feed flow (treatment capacity)

The feed flow affects the retention time of materials in the equipment, thus affecting the separation effect.

The smaller the treatment capacity, the smaller the axial flow rate of the feed liquid, the longer the residence time in the drum, and the better the separation effect; On the contrary, excessive feed flow will reduce the separation effect.

In addition, the feed flow is also related to the solid content of the feed liquid and the slag discharge ability of the centrifuge screw. Excessive feed flow may cause blocking of the drum and affect the separation effect.

Therefore, the feed flow shall be reasonably selected to match the solid content and separation requirements of the feed liquid.

Overflow plate diameter

The big end of the drum is equipped with an overflow plate, which can adjust the diameter of the overflow plate and control the liquid depth of the liquid ring layer.

The overflow plate with small diameter can add the depth of the liquid ring layer, so that the separation liquid has high clarity; On the contrary, if the diameter of overflow plate is increased, the separation liquid obtained has low clarity and poor separation effect.

Differential speed between drum and screw

The differential speed directly affects the slag discharge ability, mud biscuit degree and filtrate quality, and is one of the important parameters that need to be adjusted according to the operation condition during the operation of the horizontal spiral centrifuge.

The lower differential speed has better separation effect, but the solid particles are easy to be blocked due to the longer residence time in the drum; With large differential speed, the separation effect is poor due to the large disturbance of the spiral to the liquid layer, but it has good slag discharge ability.

Therefore, the differential speed can be determined according to the material properties, processing capacity, processing requirements and centrifuge structural parameters. The small solid content matches the small differential speed, and the large solid content matches the large differential speed.

Aspect ratio

The larger the length diameter ratio of the Allweiler horizontal spiral centrifuge, the stronger its processing ability and the better the separation effect.

Characteristics of suspension

Different solid particles in materials have different centrifugal force effects and separation effects.

The larger the particle, the simpler the separation; The too small particles are easy to mix in the separation liquid and overflow with the separation liquid.

In addition, the specific gravity difference of solid-liquid two phases and the viscosity of suspension also affect the separation effect. The greater the weight difference of solid-liquid two phases, the simpler the separation, and the smaller the viscosity of suspension, the simpler the separation.

Of course, in addition to the above factors, there are many factors that affect the separation effect of the horizontal spiral centrifuge, such as the thickness of the liquid ring layer, such as process factors, and these factors affect each other. The treatment effect is the result of the comprehensive effect of the above factors.