Redesigning Chutes And Conveying Systems To Reduce Fugitive Dust

In today’s episode of the Dust Safety Science podcast, David Wood, Senior Technical Advisor at Benetech Inc., discusses redesigning chutes and conveyor systems to reduce fugitive dust. David’s role as a senior technical advisor is to assist the sales team. He goes out to see where customers are having issues with dust and spillage, works on developing solutions, and then presents a proposal that effectively solves the problem and provides a good return on investment (ROI).

What Are Some Ways to Tackle Fugitive Dust on Chutes And Conveying Systems?

David explained that there are two main options for improving a conveying system. First, you can use containment systems, such as adding an engineered skirt system to an existing belt. This system keeps dust and material contained within a skirt box, and you can also add dust collection features. Additionally, rubber curtain baffles can help reduce dust.

To address the root cause, it’s essential to focus on the transfer chutes. Traditional chutes are simple boxes where material impacts the wall, causing dust to be released into the airflow. This dust is then carried through the system and expelled at the chute’s discharge.

In an engineered design, the material’s trajectory is captured as it comes off the head pulley and guided through the transfer chute in a continuous stream at a constant velocity. This keeps the dust encapsulated within the material stream, just like it was on the conveyor belt. By maintaining this stream through the transfer and onto the next belt, dust release is minimized.

When dealing with height drops in a transfer, instead of letting the material fall freely, it should flow down alternating surfaces in an S-pattern. This method keeps the material stream together and uses wear liners to control the velocity, balancing against gravity and maintaining a consistent speed throughout the transfer.

David added that the hood and scoop, or hood and spoon, is another method used in conveying systems. The hood has a curved shape near the head pulley, which captures the material and starts to direct it. Then, it moves onto sloped or straight surfaces that continue to contain the material. These surfaces include various curves and straight sections to guide the material through the required height. Sometimes, the system needs to divert the flow, allowing the material to switch from one belt to another or to split the flow between two belts.

What Other Engineering or Redesigns Can Stop Bulk Material Flow From Kicking Up Dust?

David said that when they refer to an engineered transfer chute, most of the design work is done using computer simulation software called Discrete Element Method (DEM). This program shows how the material is expected to flow through the chute the designer has created. DEM doesn’t tell the designer how to design the chute but instead simulates the results, providing a powerful prediction of how particles will interact with each other and with the chute. The software gives a visual representation, including video, of how the material flows. It also provides data points, often using color to represent the velocity of each particle, giving a clear picture of the flow dynamics.

While anyone can buy DEM software, it doesn’t make them an expert in chute design. Experience is crucial to knowing what works. DEM simulations are computer-intensive and can take a long time to run, so it’s important to get the chute design nearly right on the first try and then make minor adjustments. This is where the designer’s experience comes into play, allowing them to create an initial design that is close to being correct.

What is a Load Zone Containment System?

David explained that a load zone containment is often part of an engineered chute design. However, a load zone solution can be a lower-cost and effective way to address a problem. The key feature of the load zone is its adjustable internal wear liners, which can be set very close to the belt, about an eighth of an inch away. This adjustment helps contain most of the material.

There is also a skirt seal on the outside, which can be a one-part or two-part seal, that keeps fine material and dust inside the skirt box. Additionally, there are belt support options beneath the load zone to prevent the belt from sagging and creating gaps between the belt and the skirt box. The skirt box is extended to allow the material to settle and to compress dust passively in that area.

What is the Process for Devising a Fugitive Dust Reduction System?

The first step is to identify where dust and spillage are occurring. These areas indicate problems. David and his team also talk with the customer to understand their concerns. By examining these issues, they can quickly determine the root cause of the problem.

Usually, they find material buildup around the load point. They then assess the existing transfer system to see its condition and potential for improvement. An engineered design should ensure the load is properly centered and moving at the same speed as the belt to reduce turbulence. They evaluate whether the current transfer system can be adjusted or if a new solution is needed.

David explained that dust suppression and dust collection work well with engineered transfer chutes and containment systems. These systems often include dust collection points, especially for materials that are very dusty or combustible. For example, they might integrate a hood into a containment or skirt box to capture material. They would then design the skirt box to ensure the air velocity at the pickup point is effective for dust collection.

David believes there’s a clear difference between industries when it comes to dust issues. For example, coal and grain industries are well-known for dealing with combustible dust problems and have established methods for managing them. However, other industries, like cement and aggregates, haven’t faced these issues as much in the past and may not have paid as much attention to them. With new regulations coming, especially regarding silica dust, these industries are starting to become more aware and take action.

Conclusion

Managing dust and spillage in conveying systems is crucial for maintaining safety and efficiency across various industries. While some sectors, such as coal and grain, have long been aware of and addressed these issues, others are just beginning to understand the importance due to emerging regulations. By leveraging advanced technologies like DEM software and engineered transfer chutes, companies can develop effective solutions tailored to their specific needs.

Experienced designers play a vital role in this process, ensuring that systems are optimized from the start to minimize adjustments and downtime. As industries continue to evolve and adopt these advanced methods, the overall management of dust and spillage will improve, leading to safer and more efficient operations.

If you would like to discuss further, leave your thoughts in the comments section below. You can also reach David Wood directly:

Website: https://benetechglobal.com/

LinkedIn: https://www.linkedin.com/in/david-wood-57593817/

Email: [email protected]

If you have questions about the contents of this or any other podcast episode, you can go to our ‘Questions from the Community’ page and submit a text message or video recording. We will then bring someone on to answer these questions in a future episode.