The screw conveyor is normally divided into a shaft screw conveyor and a shaftless screw conveyor in the form or conveying, and is divided into a U-shaped screw conveyor and a tubular screw conveyor in the outer shape. Screw conveyors with shaft are suitable for non-stick dry powder materials and small granular materials (e.g. cement, fly ash, lime, grain, etc.) and shaftless screw conveyors are suitable for the viscous and entangled materials (for example: sludge, biomass, garbage, etc.) Screw conveyors are widely used in various industries, such as building materials, chemicals, electric power, metallurgy, coal charcoal, grain and other industries. They are suitable for conveying powdery, granular and small block materials horizontally or obliquely.