This article will take an in-depth look at vacuum conveyors.
We will go into detail about:
This chapter will discuss the purpose and functions of vacuum conveyors.
Vacuum conveyors are suctioning machines that utilize air pressure in order to move materials through an enclosed pipeline. Vacuum conveyors have broad applications throughout the industrial and manufacturing world.
Vacuum conveyors make use of a blower when transporting materials. This is an advantage over conveyors of past years, which moved materials using belts. Vacuum conveyors are mostly used for moving small or large quantities of materials like powdered chemicals and grains.
To move materials from one end to the other, conveyors utilize pressure differences caused by a vacuum. The materials are drawn to one end by negative pressure from the inlets. Bulks or dry powders perform much better since the airstream from the conveyors can easily catch them. Negative pressure is used rather than positive pressure because the chance for the continuous accumulation of dust particles is reduced and prevented.
Another benefit of negative pressure is that there is less loss of material since all the leaks in the system are directed inwards. Therefore, these types of conveyors are ideal for large applications where the materials enter the conveyor system from silos, railcars, bags, and other dusty containers. They offer self-cleaning, they are energy efficient, they are easy to install, and they have a very small footprint compared to older conveyor options.
The components of a vacuum conveyor include:
A vacuum screener is directly connected to a line of pneumatic conveying. It is able to screen through a broad range of mesh sizes. The way it is constructed is appropriate for use in pharmaceutical powders, food, chemical processes, and scalping lumps. Also included here are unwanted contaminants coming from the product stream. The processes of cleaning and operating are much easier.
The batch system is made to batch the product from its original containers, like gaylords, drums, sacks, etc. Most of them allow operators to work with a single system in order to efficiently batch the products. These products are then batched into smaller containers in different areas in the same processing facility.
The batch system usually comes with controls, the vacuum conveying system, rotary valves, and an integrated scale system used for dosing very precisely. This is a convenient system that caters to easy removal or loading of small containers.
The lift is defined as a column where the vacuum conveyor is mounted. It is a column-shaped lift that consists of casters, outriggers, and a counterweighted base. All that is needed is one air connection, and the controls of the conveyor are kept together compactly in the counterweighted base.
Most of these lifts come with additional advantages like transportation for the various applications carried out inside the plant. They also help facilitate the conveyor and the conveying process. Some of these lifts perform failsafe brake operations, meaning they halt in their positions.
As a result, the conveyor lift is prevented from failing in instances where there is air loss. There is a separate air cylinder to provide sufficient air in order to maintain the braking system. This is very beneficial, especially if the air in the plant has been lost.
This is the heart of any vacuum conveyor. Its main function is to provide suction, which is what moves the material from the source to the center where it is collected. There are two types of pumps used: motor or compressed air driven. Vacuum conveying systems use compressed air driven pumps and are maintenance free. Additionally, no heat is emitted during operation, and the pumps are easy to control and quick to react.
The pump only runs when suction is actively occurring, so at other times it will be saving energy. Powder transfer systems, which are more complex, utilize motor-driven pumps that can be kept in a separate area in the same plant if necessary. They are highly efficient and produce a lot of power. This usually happens if there is an advanced transfer system required.
When the air conveyed, along with the material, is inside the collection container, most of the particles are separated because of the drop in speed. However, the clean air finds its way through the exhaust of the vacuum pump.
Depending on the specific use of the applications, these filters consist of a wide range of materials. Some can be made of stainless steel, polyethylene, polyester, etc.
The vacuum collection container consists of a valve (sanitary butterfly). This sanitary valve helps in the creation of the vacuum and the discharge of the product. A sanitary valve is usually used in place of a discharge feeder when the batching system consists of the conveyor.
There must be a control system for all the pneumatic conveying systems that suits the applications as well as the environment. This can take many different configurations. In order to meet these requirements, the control systems can be wholly electrical or wholly pneumatic.
They may also be a combination of these two systems brought together. These systems can incorporate various units of conveying that require independent control.
This feed wand is recognized as the best procedure when dealing with transferring the product inside the vacuum system. This is usually from a container such as a drum.
A feed lance holster can be part of the wand. In order to use the feed wand, a fabric drum cover can be supplied. This drum can help the access of the powder by the feed wand; an advantage of these is that they typically come with a clear window that makes it easier for the person operating to see clearly into them.
As alternatives to a feed wand, there are provisions that can make available a feed station hopper of whatever configuration to bring the required product into the system. Typically, this type of configuration will cause the best adjustability and maximum conveyance for the material. It also allows for automation as well as well-established and reliable feed that goes straight into the system.
Fluidization of the materials using vibrations and fluidizing discs can also be incorporated for easier flow of the materials.
The initial stage of how a vacuum conveyor system works involves the vacuum pump. The vacuum pump is what produces negative pressure. This negative pressure is produced in the vacuum conveyor’s separator container.
In the second stage, air is sucked through the opening of a product feeding station. Then the material starts to move for transportation. The air that has been vacuumed goes through a filtering system located inside the separator container, and it is where the materials accumulate when they are deposited. In cases of fine dust, a cyclone will be additionally inserted into the separator. Because of the very minimal surface load, fine dust facilitates much higher flow rates.
Once the separator container is filled, the vacuum pump has to be turned off. The pressure that is in the separator container will gradually decrease to the atmospheric pressure. Then the discharge module valves open and allow the moving materials to enter the vessel receiving from the vacuum conveyor.
When removing the contents, a backflow pulse of the compressed air helps in cleaning the filter, and these filter cases can be removed reliably. In scenarios that involve adhesive materials or bridging, there are options offered by many manufacturers, including the use of units that have been passed over fluids in order to aid discharge, as well as the use of piston vibrators.
When this has been done, the valves for discharging close, and the process starts again with the vacuum pump producing negative pressure.
The vacuum conveyors are great contributors and automated additions to control. Operators need to use the appropriate equipment, including the instruments, the closed feedback, the different speed drives, and so on. Again, another point to note is the working environment with its associated hazards.
These hazards include factors like the alkalinity, the humidity, the degree of hotness or coldness, or anything to consider that may in some way affect the integrity of the vacuum conveyor system. Lastly, layout considerations pertaining to the needs of the supplier should be kept in mind so that the appropriate vacuum conveyor is selected.
Vacuum conveyors can transport many granulated bulk materials, powders, small parts, and pigments in dense and lean phase via pipes and hoses. The installation of these machines is easy and their operation is quite simple. With the use of the vacuum, the production environment can be kept clean by these systems. The constant improvement in technology, eradication of explosion risks, and hygienic cleaning solutions have increased the use of vacuum conveyors in several industries.
They are capable of transferring nano-sized materials and fine dust up to larger candies, tablets, or bottle caps. They are ideal for powders that are highly abrasive or mixtures. This equipment is able to make safe and reliable powder handling in production processes, making the work of operators easier and improving conditions in the workplace.
The different types of vacuum conveyors include:
This type of vacuum conveyor makes use of air streams at very high speeds. They also use low pressure in order to continuously fluidize the product. These vacuum conveyors are usually used for materials that do not pack when they are brought under pressure, such as grain, wood, or chips. They are also implemented for long distances.
The high velocities impart a significant amount of force on this product. A major drawback of this is that fragile materials cannot be processed through this kind of system; however, these vacuum dilute phase conveyors are helpful for hazardous applications because they minimize exposure to any toxic substances. This is why they are preferred and very valuable in agriculture, food processing, chemistry, and other industries. So if one has a material that is hazardous or strong enough to withstand high velocity, a dilute phase conveyor is the appropriate conveyor to use.
Dilute phase conveyors have been used for over a century now. Numerous challenges were faced in the creation of these machines, but many of those problems have been solved with emergent technologies. For example, the procedures and methods of test designing have been greatly improved. This has led to minimized rates of power consumption and reduced air flow.
The operation processes have also proved to be much more efficient. There has been a noticeable reduction in transport speeds, high rates of wear, and product damage. Another interesting point to note is the developments and improvements in abrasion. This development has helped to extend the lifespan of bends or pipes.
However, there are still problems in existence with no clear solutions for designers, researchers, and users. Compared to the rate of expansion of gas in conveying systems that utilize positive pressure, the rate of expansion in systems using negative pressure is still high. There are also numerous challenges associated with characteristics of the feeding of the rotary valve; these include deposition issues, venting effects, and interfacing with the pipeline.
Another problem to note is prediction of the minimum required speed when considering the moving products and the diameter of the pipe. Some things that must be taken into account are the localized deposition, the results of the prime mover, the procedure of feeding, or the subject matter in picking out and giving good definitions of the conditions for saltation.
Lastly, another challenge being faced is the operation of the system through pipelines with small diameters. There is always an unexpected problem of deposition. Due to this there is also an effect on the feeding procedure.
In comparison to the dilute phase vacuum conveyors discussed above, these types of conveyors are run by utilizing a vacuum controlled at very low speeds. This will cause a very slow movement of the product packets through the system. The main reason why the slow, dense phase is created is to minimize the excess stress on the products that accumulates over time. This will allow fragile materials to move through the conveyors.
Dense phase vacuum conveyors are also of great advantage in preventing too much buildup inside the tube. Heavy materials can be moved with this kind of setup. This use is recognized well, especially when there is a need for high-volume applications. Although, as mentioned, they are much slower than dilute phase vacuum conveyors, they are beneficial in processing abrasives such as salt and sugar, manufacturing plastics, transporting in bulk, and working with many fragile applications.
The system of dense vacuum conveying is mostly applicable for high-capacity materials. This is done from a range of short to long distances. This system can operate with a wide range of sources and reach many destinations. The low speeds provide the ideal conditions for dairy, pharmaceuticals, food, and other products that consist of both fragile and friable agglomerates.
In order to optimize the conveying system, there are numerous techniques that can be taken into consideration for special applications. One of these is the feedback of the control system in order to reduce the degradation of the product. Pulsed air can be injected inside in order to disband the flow of the product into the discrete slugs. Another technique is the use of double vessels on receiving so as to continuously convey the product and minimize corrosion; the sanitary stainless steel is also helpful.
Easier cleaning can be facilitated by designs that are well-polished or demountable and replaceable. To allow maximum flexibility, the systems can use various networks on both the inlet and outlet sections.
This conveying system’s range is limited from 66 yards (60 m) to 98 yards (90 m). This relies much on the amount of energy that is brought out by the pump or the vacuum blower.
The dense phase vacuum system has numerous advantages, which include its capability to efficiently contain food ingredients within the line. This is usually because of the vacuum’s inward pull effect.
These will always show up when looking at systems involving vacuum conveyors, even though their system is not technically an enclosed negative pressure one; still, it is of great importance to know them well. Their function is mostly identical to that of belt conveyors. However, they contain perforated holes connected to the vacuum. This will allow anything on the belt to be suctioned. For this reason, the traditional belt conveyor is very versatile.
With the addition of gripping, the products can move up much higher inclines. Vacuum belts are preferred for moving materials like cardboard boxes. As of today, they are found in various industries as replacements for traditional, older belt conveyors. They also have a broad range of applications, and some are found in elevators and assembly lines.
This chapter will discuss the applications and benefits of vacuum conveyors.
Vacuum conveyors have numerous applications across numerous fields and industries. They are found in the chemical industry for robustness and safety. They are also approved in the pharmaceutical industry due to their construction and hygiene levels. In the food industry, they are hygienic, gentle and inexpensive.
Their applications are also broad to the industry of bulk materials as modular and versatile. Another application is in the engineering plant. These conveyors are easy to integrate, so they are at home in any industry in the present day.
One challenging phenomenon in the food filling packing industry is the transportation of powder material. It affects production efficiency, product quality, and increases labor intensity for the operators. The risk of material cross-contamination is increased under such circumstances. Large amounts of dust, which is a pollutant and health hazard, can be created if the material is transported without the use of vacuum conveyors.
When the vacuum conveyors are used in the food filling packing industry, the vacuum pump of the vacuum conveyor feeder creates the vacuum flow. The material is then sucked into another silo and the structural form of the powder is not destroyed in the process.
The vacuum conveyors are thus best suited for fragile and crystal materials in the food filling packing industry. They aid in enhancing powder products’ production efficiency and quality and thus reduce production costs.
Some of the advantages of using the vacuum air pressure in food filling packing industry include:
Vacuum conveyors have a great number of advantages over other mechanical systems of powder transfers. Materials are transferred without excess dust, and they are handled gently.
They are much more reliable, easy to clean, and have a low cost of maintenance. Another point to note is that the installation and control processes are simple and quick. They are also preferred due to their outstanding hygienic design.
In comparison to mechanical transfer systems, these systems have very small footprints. Another advantage is that they are designed with high flexibility in mind. The vacuum conveyors are very adaptable for powders, tablets, small parts, pigments, granules, pellets, and capsules. In general, they are suitable for materials that are typically difficult to transport in bulk.
The considerations when choosing a vacuum conveyor system include:
The ways materials are moved fall into two categories, and understanding the difference is important to ensure the selection of the correct conveyor system. When materials are being conveyed, it means that materials are being moved from at least one pick up point and delivering them to at least one drop point.
Feeding is much more time-sensitive and process-critical when considering the quantity of the delivered material. The operator of a feeder must determine whether the feeder is required to deliver in discreet batches or on a non-stop basis. If batching, knowing the amount that must be delivered and delivering accurately between idle times is important.
The complete definition of material is made up of several important characteristics. Each must be understood very well, like flow ability, temperature, abrasiveness, and moisture content. Some of these can be influenced or influence one or more of the other characteristics because they are dynamic. Therefore it is always best to make an analysis of them all together.
There are many environmental factors that must be considered in the selection of proper equipment. With material characteristics, some of these may combine to exacerbate or cause handling concerns, while various factors may make added health and safety countermeasures a necessity. These include the potential for explosion or fire, open sources for ignition, and the presence of corrosive vapor.
The consideration that must be made when selecting between conveyor systems often comes down to the amount of room that is available for the installation of the equipment. When making a consideration on used or new equipment, particularly when there is already existence of some portions of the system, the decision must account for discharge elevation and inlet and the depth, width, and height of the ceiling in the space.
The role that cost plays cannot be denied in any project. There must be more focus on reduced energy consumption, reliability, and maintenance. It is always ideal to make a discussion of all the expenses, both initial and long-term, as soon as possible for the determination of the financial feasibility of a proposed solution to conveyance.
Some of the common issues experienced on vacuum conveyors in the transportation of material include:
The most common reason for vacuum conveyors stopping is blockages. This happens when material, which can be of different shapes or sizes, is caught in between the gears or along the pathway of the belt. The smaller material causes jamming and clogging of the systems. Bigger material causes blockages in the system that are are much more visible.
Regular checks for weak points, sharp edges, and holes in the conveyor belt can help in identifying potential blockages ahead of time.
It is important to minimize or prevent spillages when transporting material using vacuum conveyors. This can be aided by installing skirt clamps, impact beds, or belt plows. Preventing the spillages helps in minimizing downtime, minimizing cleaning time, and saving time and money.
The vacuum conveyor can misalign. This can happen if inspections, checks, and adjustments are not regularly done. In essence, mistracking is when the belt has moved too far out to one side. This shifts the system out of its intended alignment. The misalignment itself can cause or lead to spillages and blockages.
Belt spillage typically happens when the belt is poorly tensioned. Either too much or too little tension can make the belt slip off. This then leads to downtime and waste. As conveyors work on pulley systems, the belt spillages cause head pulley overuse and lead to the equipment breaking. The loss of tension is also the cause for screeching noises, grating and rattling. The belt can also stretch or warp, leading to strain on the equipment.
Vacuum conveyors are machines that use air pressure (suction) to move materials through an enclosed pipeline. There are only two different types of vacuum conveyors, dilute phase and dense phase vacuum conveyors. These two operate differently in that dilute phase vacuum conveyors utilize air streams that have high velocities and low pressure, whereas dense phase vacuum conveyors run by utilizing a vacuum which is controlled at very low speeds, causing very slow movements of product packets through the system.
One type offers some advantages over the other, but each is well suited for a specific application. Therefore, when selecting a vacuum conveyor, it is important to make considerations such as operation, material, environment, footprint, and cost. Each factor to consider makes a difference in the selection of a vacuum conveyor and allows for a purchase that fits all requirements well.
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