Screw conveyor is a kind of conveying machinery which utilizes rotating screw blades to convey bulk materials. It consists of screw blade, trough, driving device, intermediate bearing and inlet and outlet and other components. It is characterized by simple structure, reliable work, convenient maintenance, large conveying capacity and strong adaptability. It is very suitable for conveying powdery, granular and small bulk materials, such as sewage sludge, cement, lime, coal powder, grain, feed, ore and so on.

In wastewater treatment, screw conveyors are commonly used to convey sludge and grit. They can also be used to collect grit from digesters, classifiers and screens.

Structure and principle of screw conveyor

The spiral blade is the main conveying part, made of steel plate or cast iron, the surface can be galvanized or painted. The trough is the channel to hold the material, made of steel plate or composite material. The driving device provides power for the screw conveyor, which usually consists of motor, reducer and coupling. The intermediate bearing supports the screw shaft to prevent it from bending or breaking. Inlet and outlet ports are used for material entry and exit.

The conveying capacity of a screw conveyor depends on factors such as screw diameter, screw speed, trough length and material accumulation density. The larger the screw diameter is, the larger the conveying capacity is; the higher the screw speed is, the larger the conveying capacity is; the longer the length of the trough is, the larger the conveying capacity is; the larger the stacking density of the material is, the smaller the conveying capacity is.

The selection of sludge screw conveyor should be based on the nature of the material to be conveyed, conveying capacity, conveying distance and installation place and other factors to determine.

Screw conveyors are transporting the sifted sludge

Types of screw conveyor

Divided according to the angle of conveying material displacement direction

Horizontal Screw Conveyor

Horizontal screw conveyor adopts “U”-shaped trough (also can adopt cylindrical trough), lower screw speed and fixed installation structure. It is suitable for conveying loose powdery, granular and lumpy materials, such as cement, lime, calcined gypsum, coal powder, grain, fertilizer, sand, metal powder and so on. The conveying length of horizontal screw conveyor is generally not more than 60m, and the inclination is not more than 15°.

Inclined Screw Conveyor

The rotating screw is utilized to push the conveyed materials along the fixed casing and carry out the conveying work. It is similar to the horizontal screw conveyor, but its trough has an inclined angle and is used to convey materials to a higher position.

The inclined angle of inclined screw conveyor is generally not more than 60 degrees, and the conveying height is generally not more than 12 meters. It is suitable for conveying loose powdery, granular and small lumpy materials, such as cement, lime, calcined gypsum, coal powder, grain, fertilizer and sand.

Vertical Screw Conveyor

Vertical Screw Conveyor, also known as Screw Elevator, is a kind of continuous conveying machinery for conveying materials vertically. It is suitable for conveying loose powdery, granular and small lumpy materials, such as cement, lime, calcined gypsum, coal powder, grain, chemical fertilizer, sand, metal powder and so on. The conveying height of vertical screw conveyor is generally not more than 12m.

According to whether there is a central axis to divide

Screw conveyor with center shaft

Screw conveyors with a center shaft, as the name implies, have a center shaft inside the trough to support the screw blades. The center shaft is usually made of steel pipe or solid shaft and is fixedly connected to the screw blades. The purpose of the center shaft is to support the screw blades and prevent them from bending or breaking.

Screw conveyor with center shaft is widely used in chemical industry, building materials, metallurgy, electric power, grain, food and other industries for conveying powdery, granular and small lumps of bulk materials.

Shaftless Screw Conveyor

Centerless screw conveyor, also known as coreless screw conveyor, has no center shaft inside the trough, and the screw blades are directly connected to the trough wall. The structure of centerless screw conveyor is more simple, but there are some disadvantages, such as smaller conveying capacity, shorter conveying distance and so on.

Screw conveyor without center shaft is often used for conveying abrasive, sticky or easily broken materials, such as coal powder, limestone, cement clinker, ore and so on.

Features

Simple structure: the structure of screw conveyor is composed of screw blade, trough, driving device, intermediate bearing and inlet/outlet, etc. The structure is simple and easy to manufacture and maintain.
Reliable: the conveying principle of screw conveyor is simple, mainly relying on the rotation of the screw blade to convey materials, there are no complicated parts in the structure, so it works reliably and is not easy to fail.
Large conveying capacity: the conveying capacity of screw conveyor can be adjusted according to the needs, by changing the screw diameter, screw speed or trough length and other parameters, you can improve the conveying capacity.
Strong adaptability: Screw conveyor can be installed horizontally, vertically or inclined, the conveying direction can be chosen arbitrarily, and can meet the requirements of conveying different lengths, strong adaptability.
Good sealing: the trough of the screw conveyor can be completely sealed, the material will not leak in the conveying process, so the sealing is good and no pollution.
Convenient maintenance: the maintenance of screw conveyor mainly includes regular inspection, cleaning and lubrication, etc., the maintenance work is relatively simple and convenient.

Technical parameters

Common specifications: 260mm, 320mm, 420mm
Rotating speed: 16 ~ 25 rpm
Screw sheet material: stainless steel 304 and 16Mn
More parameters please contact us to customize

Applications

In cement factory, screw conveyor is used to convey cement powder, lime powder, coal powder and other materials.
In power plant, screw conveyor is used to convey coal powder, ash and other materials.
In grain processing plant, screw conveyor is used to convey wheat, corn, soybean and other grains.
In feed mill, screw conveyor is used to convey corn, soybean meal, fish meal and other feed materials.
In mines, screw conveyor is used to convey ore, mineral processing powder and other materials.