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In order to achieve optimum material flow and a controlled and uniform flow on conveyors transporting large volumes of bulk material, the transfer areas at the conveyor belts and silos must be designed not only to accommodate, but also to facilitate the flow of handled bulk. Unfortunately, because so many conditions can limit the flow of bulk material, designing a conveyor that would address every material plugging problem is nearly impossible. Even modest changes in moisture content can cause sticking to the chute or walls of storage units or agglomeration at low temperatures, especially if the material stagnates for some time. Even in continuous operation, bulk material can compress, and physical properties often change due to natural variations in deposits, different suppliers or specifications, or if the material has been in storage. If it continues to accumulate, material may come to rest on the belt scrapers and material residue may settle on the return run of the belt, fouling the rollers. In the worst case, the bearings can lock up completely. To overcome these problems, a variety of devices commonly referred to as "flow aids" can be used.

What are drainage aids? As the term implies, flow aids are components or systems installed to help transport material through a chute or silo, to control dust and spills. Flow aids come in a variety of forms, including rotary and linear vibrators, high and low pressure air guns and aeration devices, as well as low friction coatings, and chute designs. to promote efficient flow of bulk materials. These modular systems can be combined to complement each other and improve performance. The components can be used for virtually any bulk material, including hazardous and extreme working and temperature conditions. One of the main advantages is that an operation can gain a level of control over the material flow that is not possible otherwise. When using flow aids, it is essential that the chute and support components are sound, and that the flow aids are properly sized and fitted, as the operation of these devices may create potentially damaging stresses on the structure. A properly designed and maintained chute will not be damaged by the addition of properly sized and fitted flow aids. It is also important that any unclogging device is only used when unloading is possible (hatch open) and the material can flow freely. The best practice is to use flow aids as a preventative solution, controlled by sequencers or sensors to prevent material build-up, rather than waiting for the material to accumulate and restrict the flow. Using these flow aids in preventative mode improves safety and saves energy, as unclogging aids can be programmed to operate only when needed to control the flow. build-up and clogging.

Air cannons : One solution for managing the build-up of material in chutes and tanks is the low pressure air gun, developed and patented by Martin Engineering in 1974. Also known as the "air blaster", it uses compressed air. of a plant to abruptly evacuate the accumulation. Cannons can be mounted on metal, concrete, wood or rubber surfaces. The basic components include an air reservoir, a quick exhaust valve with a trigger mechanism and a nozzle to generate the desired airflow to most effectively clear the build-up.

The device does the job when the compressed air (or other inert gas) in the tank is suddenly released from the valve and directed by a special nozzle, which is strategically positioned in the transfer area, the preheating tower, the ducts. , carnals, cyclones or any other area of ​​the process where material accumulates. Often installed in series and precisely sequenced for maximum effect, the system can be synchronized to best suit the industrial process and material characteristics. Air blasts help break down material build-ups and clear clogged pathways, allowing solids and / or gases to resume their normal flow. In order to customize the solution using air guns, specific air blast characteristics can be achieved by tailoring the operating pressure, tank volume, trigger head design, and nozzle shape.

In the past, when material build-up became a problem, users would go into degraded mode until the next scheduled shutdown, and had to endure costly downtime before installing an air cannon array. It can cost a business hundreds of thousands of euros per day in lost production. Many designers are proactively incorporating the necessary reservations so that future airgun installations can be completed smoothly, and without extended downtime. New technology has even been developed for installing air guns in high temperature applications without plant and production downtime, allowing specially trained technicians to mount the guns on furnaces, preheating towers, clinker coolers and other areas of the process as production continues uninterrupted.