While the hopper functions as the mouth of the funnel, the chute serves as the narrow tubing connected to it. Both of these components undergo wear and tear, mainly due to the abrasive actions of the bulk materials that pass through them, and there are ways of protecting them, such as with ceramic coating, if abrasion is an issue in your system.
Continue reading to find out more about what these vital components do in pneumatic conveying systems.
Pneumatic Conveying Systems: A Brief Overview
Unlike other types of conveying systems, a pneumatic conveying system doesn’t have moving mechanical parts that are in direct contact with the materials being conveyed. Instead, it uses air to move materials along tubes, from one site to another, within a fixed area such as a factory floor or a warehouse-silo facility.
Pneumatic conveying systems have the following basic components:
- Hoppers and chutes
- Motorized pumps
- Tubes or pipes
- Elbows and other fittings
- Lump breakers
Dry bulk materials, including plastic pellets, cereal grains, pet food pellets, flour, sugar, and aggregate construction materials, are conveyed within pneumatic systems for processing, packing, and storing. It typically starts with the delivery trucks and loaders: material is loaded into the silos, and then released in hoppers and chutes. From there, the product is conveyed via tubes. Sometimes, it may also need to pass through lump breakers or hammer mills to prevent clogging.
Bulk materials behave like fluids under certain conditions, such as when being blown by air inside a pneumatic conveying system. Given the same amount of pressure and air speed, the dense phase of materials flows slower compared to the dilute phase of the same bulk material moving through the system.
In the dilute phase, materials are suspended in air. They’re also less chunky, but can be very abrasive depending on the type of material as well as the speed at which it’s being conveyed. Some components, like the hopper and chutes, need ceramic cyclone lining to protect them from abrasions. This is an important safeguard given that these components are expensive and not easily replaceable.
What Are Chutes And What Do They Do?
Chutes could refer to factory chutes, grain chutes, or any other type of chute, depending on the materials they’re intended to convey. Chutes are basically tubes that usually have a square cross-section. They’re connected to the hopper, forming a funnel-like structure. Chutes are usually positioned at a steep angle to allow bulk solids to slide down with the help of gravity.
Few chute designs have perpendicular angles relative to the ground. Spiral designs are more common because they help guide the materials down in a relatively stable manner. Additionally, compacting and lumping are prevented if the bulk solids slide at a certain calculated speed, which can be facilitated by the way the chute has been designed. This also prevents further powderization of the product, which is especially important if you’re conveying a fragile material.
What Are Hoppers And What Do They Do?
Hoppers are similar to the mouth of a funnel, and can either be conical or pyramidal in shape. A large entry point allows for the convenient loading of bulk materials, like cereal grains or flour, which are then poured down the chute and into the tubes for conveyance.
The big mouth in a hopper’s design does more than just allow for easy material loading. It also minimizes spillage, especially when pouring powdery materials into the pneumatic system. Hoppers are typically made from thin steel, and are specific to the pneumatic conveying system they’re being used in. They are generally also custom-fabricated based on the specs given by a company. Although there are standard sizes, many companies require certain specifications, so the size and material of hoppers depends on the industry and application they’re being used in.
Another important customization is to have your hopper lined with ceramic. This provides superior resistance to abrasion and wear, offering protection right where it’s needed.
Hoppers also need to be either bolted or welded onto the chutes and the frame of your conveying system. The dimensions of any replacement hoppers must be precisely measured so that they fit into the system without disrupting the existing components.
Why Do You Need Ceramic Coating In Chutes And Hoppers?
Just like the tubes, elbows, and diverters, chutes and hoppers are also subjected to abrasive wear in pneumatic conveying systems. Although these components don’t require active airflow, the bulk materials flow through them at high speeds, resulting in high impact areas where the product repeatedly wears against component parts.
Depending on the type of materials that are being passed through the chutes and hoppers, the wear process can significantly shorten the lifespan of these components. For example, plastic pellets are more abrasive than flour, so extra precautions might need to be taken here. In a nutshell, higher levels of abrasiveness means shorter life expectancy for components.
Ceramic coatings can protect the interior surface of the hoppers and chutes from abrasion and heat. By encasing them in a protective layer, it means the effects of abrasion are transferred to the outer coating. As a result, the components themselves will be in less contact with the materials being conveyed, and in turn more resistant to abrasive corrosion and wear.
What Is Cyclone Lining?
Cyclone lining is basically a protective layer of industrial ceramic inside a multi-cyclone system or cyclone separator. Types of ceramics commonly used in cyclone lining include tungsten carbide or alumina ceramic. Similar linings can also be used in other components to prevent abrasions.
Cyclone separators, more commonly known as cyclones, are part of anti-pollution systems in industrial facilities. These devices separate particulate or solid materials from exhaust gases. Cyclones operate using the principle of centrifugal force. Since it removes larger particles from the air before filtration, it’s classified as a precleaner.
What Are The Advantages And Disadvantages Of Cyclone Lining?
The primary advantage of a cyclone lining is its hardness. It has a Mohs hardness grade of 9, which is second only to diamond. This means that it’s hard to scratch, making it resistant to abrasion. Another main advantage is heat resistance, allowing them to be used in high temperature applications.
On the other hand, the hardness of cyclone linings have one main disadvantage: their susceptibility to high impact force. This means that they can crack under the sheer force of expansion and contraction of the metal components they protect.
When Would You Typically Need Cyclone Lining?
Cyclone linings are needed for cyclone systems, as well as for other components that are subjected to abrasive materials. They work by protecting interior metal surfaces from small particles travelling at high speeds, thereby preventing corrosion and other types of abrasive damage.
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Progressive Products, Inc is a full service provider of pneumatic conveying components specializing in abrasion resistant products such as ceramic backed fittings and wear resistant hoppers, chutes, cyclones, and target boxes.