Effective Strategies for a Cleaner and Safer Industrial Environment
Controlling dust at conveyor transfer points is crucial for maintaining a clean, safe, and efficient work environment. An effective dust control system is built upon four key design parameters: limiting air entry into the enclosure, restricting the spread of the material stream, minimizing material drop height, and controlling air speed within the enclosure. Let's delve into each of these parameters in detail.
1. Limit the Amount of Air Entering the Enclosure
Preventing excess air from entering the enclosure at the head pulley of the discharging conveyor can be achieved without sophisticated or costly measures. Here are some practical steps:
- Rubber Curtains: Install conventional rubber curtains at the belt’s entrance and exit points. These curtains help seal the openings and reduce the amount of air entering the enclosure.
- Sealing Openings: Seal other openings, such as those around pulley shafts, to further prevent air infiltration.
- Inspection Doors: Ensure that inspection doors are kept closed when not in use. This simple step can significantly reduce the intake of air at the discharge end of conveyors.
By limiting the air entry, the overall dust generation can be significantly minimized.
2. Limit the Spreading of the Material Stream
As materials move through the transfer point, they interact with the air in the enclosure, causing dust to be carried along. Keeping the material stream consolidated is essential to minimize dust generation:
- Deflectors and Engineered Hoods: Use deflectors or engineered hoods and spoons to maintain a cohesive material stream. While deflectors can sometimes cause flow problems, engineered hoods and spoons are designed to handle material flow efficiently without creating issues.
- Engineered Chutes: For systems handling large volumes or high-speed materials, engineered chutes are essential. They help control the material flow and reduce the spreading of the material stream, thereby minimizing dust generation.
Maintaining a consolidated material stream ensures that less air is carried along with the materials, reducing dust dispersion.
3. Limit the Material Drop Height
In conventional conveyor systems, materials free-fall from one belt to another, dispersing and creating voids filled with air. This air is then pushed away when the materials land, generating positive pressure and dust. Limiting the drop height is a key strategy to address this issue:
- Reduced Drop Height: Minimize the distance materials fall between conveyors. This reduces the force of landing and the outward pressure of air, thereby reducing dust generation.
- System Design: Implementing this strategy in existing systems can be complex. However, during the design phase, positioning conveyors closer together can significantly limit the material drop height.
By minimizing the drop height, the amount of entrained air and resultant dust can be effectively controlled.
4. Limit the Air Speed Inside the Enclosure
The velocity of air within the conveyor enclosure plays a critical role in dust control. High air speeds can lift dust particles and carry them away, while lower speeds help settle the dust:
- Cross-Sectional Area Adjustment: Adjust the cross-sectional area of the duct formed by the conveyor chute and skirtboard. Increasing or decreasing this area can change the air velocity within the enclosure.
- Below Pickup Velocity: Ensure that the air speed inside the enclosure remains below the pickup velocity of the dust particles. This helps prevent dust from becoming airborne and dispersing throughout the facility.
By controlling air speed within the enclosure, dust particles are less likely to be lifted and carried away, maintaining a cleaner environment.
Conclusion
A comprehensive dust control system at conveyor transfer points involves addressing these four key design parameters: limiting air entry, restricting material spread, minimizing drop height, and controlling air speed. Implementing these strategies can lead to significant improvements in dust control, enhancing the safety, cleanliness, and efficiency of industrial operations.