How flow aids can help conveyor operation
A series of air cannons can be programmed to deliver precisely-timed operation for maximum benefit. Photo: Martin Engineering
Transfer chutes and vessels must be designed not just to accommodate – but to actually facilitate – the flow of the cargo they will be handling in order to achieve a controlled, consistent flow on conveyors handling large volumes of bulk material.
Unfortunately, because so many conditions can hamper effective cargo flow, engineering a conveyor and chutework that handles every material situation is virtually impossible.
Even modest changes in moisture content can cause adhesion to chute or vessel walls or agglomeration at low temperatures, especially if a belt is stagnant for any period of time. A bulk material can become compressed even during continuous operation, and physical properties often change due to natural variations in the source deposits, suppliers or specifications – or if the material has been in storage.
If left to build up, material can encapsulate belt cleaners and deposit harmful carryback onto the return side, fouling idlers and pulleys. At worst, systems can become completely blocked by relatively small changes.
To overcome these issues, devices such as flow aids can be employed.
What are flow aids?
As the term implies, flow aids are components or systems installed to promote the transport of materials through a chute or vessel, controlling dust and spillage.
Flow aids come in a variety of forms, including rotary and linear vibrators, high- and low-pressure air cannons and aeration devices. Additionally, low-friction linings and special chute designs promote the efficient flow of bulk materials.
These modular systems can be combined in any number of ways to complement one another and improve performance. The components can be used for virtually any bulk material or environment, including hazardous duty and temperature extremes.
One of the primary advantages of flow aids is operations can obtain a level of control over the material flow that is not possible any other way. When employing flow aids, it’s critical that the chute and support components are sound and that the flow aid is properly sized and mounted. The operation of these devices can create potentially damaging stress on the structure, but a properly designed and well-maintained chute will not be damaged by the addition of correctly sized and mounted flow aids.
Also, it’s important that any flow aid be used only when discharges are open and material can flow as intended. The best practice is to use flow aids as a preventive solution to be controlled by timers or sensors to avoid material buildup, as opposed to waiting until material accumulates and restricts the flow.
Using flow aids in a preventive manner improves safety and saves energy because they can be programmed to run only as needed to control buildup and clogging.
Air cannons
One solution to manage material accumulation in chutes and vessels is the low-pressure air cannon.
Also known as an “air blaster,” an air cannon uses a plant’s compressed air to deliver an abrupt discharge to dislodge buildup. Cannons can be mounted on metallic, concrete, wood or rubber surfaces.
The basic components of an air cannon are an air reservoir, a fast-acting valve with a trigger mechanism and a nozzle to distribute the air in the desired pattern to most effectively clear the accumulation.
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