I. Core Types and Features of Screw Conveyors
Screw conveyors propel materials through the rotation of spiral blades. Based on their structure and function, they can be divided into the following seven categories:
1. Horizontal Screw Conveyor
- The most common type, with a conveying angle of less than 20°, suitable for granular/powdery materials (such as cement and grain).
- Advantages: Simple structure and low maintenance.
- Limitations: Conveying distances are typically ≤ 40 meters (according to the Mechanical Engineering Handbook).
2. Vertical Screw Conveyor
- Conveying angle of 90°, with a lifting height of up to 15 meters (according to ISO 1050).
- Applications: Grain processing and vertical conveying of chemical raw materials.
- Key Parameter: The speed must be greater than 200 rpm to ensure sufficient centrifugal force.
3. Shaftless Screw Conveyor
- Eliminates the central shaft, preventing entanglement, and is suitable for viscous materials (sludge, food waste).
- Industry Case Study: 80% of sewage treatment plants use this type of equipment (China Environmental Protection Industry Association 2023 Report).
4. Flexible Screw Conveyor
- The spiral can bend in multiple directions, adapting to complex spatial layouts.
- Typical Application: Concrete conveying at construction sites.
II. Special Function Derivative Types
5. Twin Screw Conveyor
- Parallel twin helices increase conveying capacity by 50%-100%, suitable for high-volume production lines (such as fertilizer production).
6. Spiral Tube Conveyor
- Fully enclosed pipe design prevents dust leakage and complies with GMP pharmaceutical standards.
7. Variable Diameter Screw Conveyor
- The spiral blades have a gradually changing diameter, achieving material compression or mixing, often used in feed processing.
III. Key Selection Data
- Capacity Comparison:
- Horizontal: 5-100 m³/h
- Vertical: 10-60 m³/h
- Shaftless: 20-300 m³/h (Data Source: German SCHNEIDER Conveying Equipment Technical Manual)
- Power Matching: Horizontal conveying requires approximately 1.5-3 kW of motor power per 10 meters. Vertical conveying requires an additional 30% redundancy.