Baghouses and Cartridge collectors are very good at removing dust from their air. However, when the dust concentration is high, or the dust is abrasive, wet, sticky or fibrous, the baghouse filters can have issues.  

• High concentration will plug of filters quickly.
• Abrasive dust will cause holes to develop in the filters.
• Wet and sticky dust will plug up the filter and/or cause filter failure.
• Fibrous dust will not easily fall to the hopper causing filters to plug.

Installation of a cyclone pre-filter is an ideal way of extending filter life.  The cyclone uses centrifugal forces to capture the dust and remove it from the airstream.  Often times the cyclone will remove 80-90% of the dust before a baghouse or cartridge collector.  This allows the filters to concentrate on the smaller dust that makes it past the cyclone.

And if you have a pulse-on-demand controller for your baghouse, you will further extend the filter life, as the filters will only be cleaned when required.

What is a cyclone dust collector?

Cyclone dust collectors are dust collectors that use centrifugal motion to remove dust from an airstream. They don’t have any moving parts and don’t use filters for dust removal. Most cyclones are vertical in design, even though Aerodyne Environmental has compact horizontal cyclone designs. They are often used as pre-filters to increase baghouse, cartridge collector and wet scrubber system efficiencies.

What is a cyclone pre-filter?

Cyclone pre-filters are cyclones installed before a baghouse or cartridge collector to increase the removal efficiency of the system.  They extend filter life and lower utility usages. The cyclone pre-filter is often used on those applications that have “Tough” dust.  “Tough” dust would be dust that is abrasive, hygroscopic, fibrous and/or wet. Often times this dust will cause operational issues with baghouse and cartridge collectors.

Why install a cyclone pre-filter?

Cyclone pre-filters are installed to optimize a dust collection system. This could mean increasing the removal efficiency of an existing dust collection system. It could be to extend filter life by decreasing the dust loading the filters are seeing, thereby decreasing the cleaning required. 

Additionally, cyclone pre-filters will lower compressed air/plant air usage by increasing the intervals between cleaning when a pulse-on-demand control system is used with it. And in those special applications, the Aerodyne SplitStream cyclone can add hot or cold air into the dirty airstream, thereby treating the air while collecting dust.

Signs You Need a Pre-Filter

The following are some signs that your dust collector isn’t operating up to par and you should look at installing a cyclone pre-filters.

1. There is a high pressure drop across your filters. This is caused by the dust building up on the filters and not being cleaned off fast enough.  The high pressure drop causes the fan to pull less air to compensate, thereby letting more dust out on to the shop floor.
2. Filters are being replaces too fast! The most common filter failures are by developing holes or plugging up.  Both failures are tied to high dust loadings.
3. Valuable product or raw material is being disposed in the dust collector waste due to contamination. As stated above, filters build up dust layers to provide the removal efficiency. Those filters will retain the material over time. If the material is valuable, this can be a lot of money that is going to waste. Pre-filters will allow the material to be collected and used in the process or product before it can be contaminated in the filters.
4. Do you have a high cost of water treatment and disposal of the scrubber blowdown? When wet scrubbers capture particulate, slurry is formed. This slurry will then have to be disposed. It will often be sent to a water treatment plant. The water treatment plant might be dedicated to the facility or municipal. Either way, additional costs are added to treat the slurry before it is disposed of or reused. A pre-filter removes a portion of the material before it is put into slurry, thereby saving costs on waste-water treatment.
5. Similar to above, since wet scrubbers form slurries, any valuable material collected in the wet scrubber will be in that slurry. So, unless the desired state of the material is within the slurry, it will have to be processed to make it useful. This means additional steps (and expense) are required to recycle the material. A cyclone pre-filter removes the material dry, before it is in slurry, thereby saving costs.

So, before you decide to purchase a new dust collector, look into the benefits of installing a cyclone pre-filter.  You just might save yourself money!

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Designing a ventilation system always involves considering space constraints. Ductwork, which is essential for air distribution, occupies space within the facility, and its design must efficiently use the available area while ensuring optimal airflow.

Furthermore, complying with NFPA regulations often requires placing dust collectors outside the primary working area due to safety concerns. This external placement adds an extra layer of space management complexity. Additionally, dust collectors are typically mounted on structural supports known as skids, which simplify installation and relocation but also consume additional space within the facility. Therefore, creating an effective ventilation system design requires careful consideration of how these elements harmonize within the given space while meeting safety and efficiency requirements.

Aerodyne's GPC cyclone offers a practical solution for applications where space is a premium concern. Its compact design and efficient performance allow it to seamlessly replace bulkier equipment, making it a space-saving choice for a wide range of industries. By doing so, it not only maximizes available workspace but also simplifies maintenance and enhances operational efficiency. This versatility makes the GPC cyclone a valuable asset, offering a viable and efficient alternative to traditional, space-consuming equipment in various applications. 

Aerodyne GPC Cyclone

The GPC cyclone's compact design offers remarkable space-saving advantages, as it can be accommodated in areas that are only half to a third of the size required for traditional cyclones, as shown in the attached documentation. This compactness often permits indoor placement, aligning with NFPA-654 7.13.1.1.2 (2) regulations. Various industries, including those operating clean rooms, mines, vehicles, and portable systems, can capitalize on these space-efficient attributes.

Furthermore, the GPC cyclone's design introduces the opportunity for installation in smaller spaces, potentially replacing the need for extensive ductwork, including 90° elbows. Additionally, it can serve as an effective pre-filter for existing cartridge collectors, baghouses, and electrostatic precipitators. This adaptability opens doors to innovative system configurations, such as positioning it above a conveyor belt to recapture particulate matter and reintroduce it onto the conveyor, showcasing the versatility and space-saving capabilities of the GPC cyclone.

The GPC cyclone by Aerodyne provides an added advantage by eliminating the need for an equipment skid. Many companies accustomed to traditional cyclones may hesitate to incorporate a pre-filter or cyclone dust collector into their skid or unit due to space constraints. However, GPC cyclones can be conveniently mounted on various equipment, such as on top of a dryer, behind a crusher, or at the inlet of a cartridge collector, without requiring a skid. This flexibility simplifies installation and ensures that space considerations do not impede the adoption of efficient dust collection solutions.

Moreover, the adaptability of GPC cyclones extends to marine applications, where space efficiency is paramount. Unlike traditional cyclones that demand multiple levels of a vessel's decks, a GPC cyclone can be installed on a single deck, greatly enhancing the practicality, serviceability, functionality, and feasibility of incorporating cyclone-based dust collection systems on ocean or lake vessels. This versatility underscores the GPC cyclone's ability to provide effective dust collection solutions without imposing significant space-related limitations. 

With these savings in space, facilities can operate more efficiently and avoid floor space issues. For more information on the GPC, click on the link below or contact Aerodyne at dc@dustcollectorhq.com or by phone at (440) 543-7400.

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Aerodyne manufactures two different types of cyclones - the GPC (Ground Plate Cyclone) and the SplitStream Collector. These Aerodyne cyclones are not the traditional cyclones with which you are probably familiar. Both cyclones can be designed for vertical or horizontal installation; traditional cyclones can only be vertical. The Aerodyne GPC and SplitStream cyclones also provide high particulate removal efficiency. The following describes the different cyclones that are available along with their advantages and disadvantages.

Traditional Cyclone

The typical cyclone design consists of a tangential inlet and a long-tapered body. Centrifugal forces force particulate out toward the walls, and gravitational forces direct the dirty gas stream downward through the narrowing body. As the gas stream becomes constrained in the narrow end of the cyclone body, a phenomenon known as “vortex-reversal’’ occurs in which a secondary inner-vortex is generated and moves upward through the center of the primary vortex where it is exhausted from the collector. Dust near the walls fall into the cyclone hopper and out of the airstream. The traditional cyclone must be vertical in design to operate effectively.

Vortex-reversal is one of the primary causes for inefficiencies in cyclonic dust collectors. As the inner vortex travels up through the cyclone, it takes with it any fine dust particulates that did not have the inertia to be forced tight to the collector walls.

Another issue that can develop with traditional cyclones is that an integral hopper could have dust re-entrainment into the clean airstream. Oftentimes, traditional cyclones will install a dust trap to prevent re-entrainment. The dust trap is located below the cyclone hopper and is designed to minimize particulate re-entrainment. If you’ve seen a cyclone with what looks like a pocket underneath it, it has a dust trap.

Aerodyne GPC Cyclone

The GPC cyclone uses a combination of a sloped spiral inlet and fixed ground plate to provide several distinct advantages over the traditional cyclone dust collector described above. 

First, a spiral inlet directs the dirty gas stream toward the ground plate and hopper of the collector. This efficiently begins the centrifugal motion of the air without any dead spots. The fixed ground plate, utilized by the GPC removes the requirement of a long-tapered hopper. The ground plate provides the vortex-reversal, rather than the geometry of the tapered hopper in traditional cyclones.

As the dirty gas stream strikes the convex ground plate; fine particulate, which has not completely made it to the collector walls, is deflected into the hopper. The ground plate also shields collected particulate from the clean air, acting as a barrier between the separation chamber and collection hopper; Therefore, no separate dust trap is required.

The GPC design allows it to be much smaller than traditional cyclones and includes 6 sizes under 8ft3 per NFPA 654. A GPC cyclone is usually less than half the height of a traditional cyclone. The ground plate also removes the requirement of gravity, so it can be designed for a horizontal installation, with virtually no effect on collection efficiency. The horizontal GPC is around 1/3 of the height of a traditional. The removal efficiency is high (99% of 20 micron particulate*).

* spherical dust, specific gravity of 1

Aerodyne SplitStream Collector

The Aerodyne SplitStream Collector uses two airstreams to remove particulate in the air. The primary air stream enters the cyclone and proceeds through a mechanical spinner. The spinner imparts centrifugal motion into the airstream, thereby forcing dust particulate toward the cyclone walls.

A secondary airflow enters the cyclone near the clean air exit. The secondary air proceeds through nozzles or vanes as it enters the cyclone. The secondary air then rotates around the outer edge of the cyclone, collecting particulates and delivering them into the hopper. The secondary air then reverses direction and joins the primary air and leaves the cyclone. Since the SplitStream Collector has no moving components, it is capable of handling a wide range of materials, while requiring minimal maintenance.

Particulate that is abrasive, fibrous, friable, sticky, or hygroscopic can be separated and collected for air pollution control or reclamation. The secondary air ensures that the dust doesn’t contact the walls. This minimizes wall abrasion for abrasive applications and areas. For particulate that is sticky, the secondary airflow keeps the dust from building up on the walls.

The SplitStream Collector has a very high removal efficiency of light, fluffy particulate that floats in the air. The secondary airstream also gives the option to heat up or cool down the process air and material. Removal efficiencies as high as 99% of 7- 10 micron dust range are normal*.

* as measured in limestone testing

To learn more about the different types of Dust Collection Methods, click here to download our free white paper. To request a brochure of the Aerodyne GPC Dust Collector, please visit www.DustCollectorHQ.com. For more information regarding the full line of Aerodyne industrial dust collection products and material airlock valves, call (440) 543-7400, toll-free at (800) 358-7546, or e-mail dc@dustcollectorhq.com.

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Smaller cyclones avoid many of the disadvantageous and time-intensive aspects of larger cyclones, including those relating to installation and regulatory compliance. Here are the five frequently asked questions about using small dust-collection cyclones.

How does GPC technology shrink the size of a cyclone without hurting efficiency?

Cyclone dust collectors are designed with a descending cone. Particulate laden air enters an inlet at the top and rotates down, exiting at the bottom while clean air is exhausted from the top. Dust is thereby separated from the airstream for recovery or later disposal. Distinct cyclones have emerged on the market that use GPC technology. These changes the shape and structure of the cyclone to make it just as efficient as much longer cyclones for the same volume of airflow passing through them.

GPCs have a ground plate located inside the cyclone. It intercepts dust in the airstream, causing particulate to divert toward the hopper, and also to lose momentum and fall out of the airstream. It also intercepts the airflow, thereby preventing dust re-entrainment from the hopper. What’s more, this technology is less dependent on gravity, enabling horizontal installation of the cyclone—very helpful where overhead space is limited.

Can a small cyclone reduce the cost of explosive dust applications?

More than 70% of industrial dusts are explosive, so venting for explosive dust is a common feature of plants. Potentially explosive dust requires the use of an explosive vent and ductwork in strict compliance with NFPA (National Fire Protection Association) standards. In general, in the event of an explosion in a cyclone, the goal is to control the location of the explosion, i.e. outside the building and away from people. Often it is more practical to locate the cyclone outside. This adds additional costs for a concrete pad and long ductwork runs. It also introduces the effect of weather that can shorten the lifetime of equipment.

Are horizontal cyclones easier to clean?

Standard cyclones may be time-intensive to clean, owing to flanges and small access doors.

A horizontally installed GPC cyclone typically features a wide removeable backplate, allowing it to be cleaned in a fraction of the time that a traditional cyclone requires. The bolts on the backplate can even be replaced with quick-disconnect clamps, further reducing maintenance time.

How can point-of-use dust collection cut costs?

Small dust collection cyclones are easier to install at the point of use, i.e. directly adjacent to a dust production area. This allows reclamation before the dust is mixed with other dusts in a central dust collection system. It’s always better to recover as much of your product as possible so you can sell it or reuse it, instead of letting it go into costly filters.

Point-of-use dust collection also minimizes buildups of material in the ductwork, as much less dust is travelling through the ducts to reach the main collector.

Can small GPC cyclones be used on mobile dust collection applications?

Any mobile dust collection application needs to maximize the available space and minimize weight. A big cyclone takes up precious space on a vehicle. Often a cyclone must be lowered before travel, to fit under obstructions such as bridges, and then raised to a vertical position when it gets to the job site.

Compact enough to fit on semi-trucks, trains, and ships, horizontal cyclones don’t need to be raised and lowered. The cyclone will already be in operational position while also easily fitting under bridges or into small spaces.

Aerodyne experts make a big deal out of small. For a consultation about the cost savings of small cyclones, or to discuss maximizing the efficiency of your current system with NFPA compliance, contact the experts at (440) 543-7400 or DC@DustCollectorHQ.com.

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A manufacturer of grinding wheels in Niagara Falls, N.Y., needed to replace an existing dust collector used to collect dust coming off a rotary kiln. Initially, a bag house collector was considered to be the obvious solution. However, because the problem involved high temperatures – 700° F and above – specific efficiency requirements, moisture content problems, and future maintenance issues, the purchase of an Aerodyne SplitStream grinding dust collector was justified.

Aerodyne SplitStream^™ Cyclone Dust Collector

The volume of gases being handled was estimated at 4,000 CFM at 700°F, according to the specifications of their previous cyclone. Using this information, a S4500 SplitStream grinding dust collector was selected and installed.

When the collector was started and the flows were checked, the company discovered that only 2,500 CFM at 500°F was needed to ventilate the kiln. Even at this lower-than-expected inlet flow rate, the results were excellent. No visible carry-over was detected, and the SplitStream dust collector captured materials much finer than previously collected.

The plant was satisfied it had made the correct decision and avoided the headaches and maintenance issues of a bag house. After several   months in operation, abrasion   wear   was   not   evident  on   the   collector. Consequently, the company ordered two more Model 4500 SplitStream grinding dust collectors.

The lack of a filter media and Aerodyne’s unique design make the SplitStream collector perfect for applications involving high temperatures and abrasive materials.

The Aerodyne SplitStream dust collector achieves high efficiency by forcing dirty gases into a powerful centrifugal motion. The centrifugal action throws dust particulate out of the gas stream. A secondary air stream carries the dust particulate to the hopper, keeping dust away from the collector walls and reducing sticking and abrasion. As a result, the SplitStream dust collector virtually eliminates maintenance problems common to other types of cyclones. The prevention of particulate contact with external walls is a major factor in the unit’s ability to achieve high efficiency ratings.

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Material of construction is extremely important to the durability of a piece of equipment. The suitability of the materials of construction is based on the process, which includes the different components, phases, temperature, and pressure. For example: a cyclone’s material of construction would be dependent on the following:

Material (dust) Being Collected

Properties of the dust being might dictate the materials of construction. Food or pharmaceuticals will usually require stainless steel to prevent / minimize contamination. Carbon steel is often acceptable for wood applications. Other times, the material properties require a special material. For example, abrasive material might require AR steel or a coating to help prevent erosion of the cyclone.

Chemical Composition

The chemical composition of the process can dictate the materials of construction. If a component will react with the materials of construction, it could cause premature failure. For example, water or high humidity can cause rusting of carbon steel so stainless steel might be better suited. Or if an acid is a component of the gas stream, then a high alloy metal or fiberglass construction might be better suited.

Temperature and Pressure

High or low temperature can cause materials to change their properties. Material can become brittle or they may react more with components. For example fiberglass can’t handle higher temperatures whereas metals usually can. And some material might have good compatibility at lower temperatures but very poor compatibility at higher ones. Sometimes pressure can affect the material properties, but usually it will affect the thickness of the walls.

Aesthetics

Some customers have plant requirements for their equipment. For example, a food or pharmaceutical facility may require stainless steel construction even though the equipment is on the waste process and everything will be disposed of.   In a similar vein, the finishing of the equipment might be determined because all the other equipment has a high polished finish and the customer wants it to fit in.

So, when determining the materials of construction, there are many factors that contribute. It is best if the end user, with help from the vendor(s), determine the materials of construction. The end user usually knows the process better than the equipment manufacturer and therefore is in the best position to determine the materials of construction.

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Rotary valves will occasionally jam. This can happen when material gets between the rotor and the housing or when oversized material cannot fit into the rotary valve pockets.   Depending on the type of jamming that is happening you handle the situation differently.

Space Between Rotor and Housing

Rotary valves have a space between the rotor and the housing. This space allows the rotors to rotate freely but it can also allow air to leak across the valve. When materials falls on the rotor edge it can buildup and jam the rotary valve. So for existing rotary valves, you might have to replace or modify the existing rotor. Beveling or chamfering the rotor edges help the material to fall off the edge and into the valve pockets.

When Jams Caused by ...

For jams caused by oversized material, a valve with larger pockets is required. This could mean a larger rotary valve or replacing the rotor with a rotor containing one less pocket. Please note if the rotary valve is on an explosive application, NFPA requires a minimum of six vanes on the rotor. If these options aren’t possible, looking into a double dump valve might provide larger clearance for oversized material to pass through.

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One of the issues when figuring out if your dust is explosive is the particle size of the dust and the location where you are assessing the dust. Material that consists of very large particles sizes (larger than 500 micron) tend not to be explosive. While larger particles can catch fire, they tend to prevent explosions. However, this might not be as straight forward as you think.

Is the Process Explosive?

Let’s assume that you have a conveyor belt that feeds a grinder which then empties onto another conveyor belt which feeds a bagging station. Let’s assume that the material starts out with a particle size distribution of 10% less than 500 micron and 90% greater than 500 micron of a combustible material. After it is fed into the grinder, its target size is around 200 microns. The question is, is this process explosive? Your 1^st thought would be that before the grinder, the dust is too large to be explosive, and you might want to take the material leaving the grinder and have it tested. So you test the material leaving the grinder on the conveyor and find out it isn’t explosive. Therefore you assume the whole process isn’t explosive. However, this might give you a false reading.

Is the Dust Cloud Explosive?

For example, the material falling on the conveyor belt that feeds the grinder creates a dust cloud. That dust cloud is made up of the finer particles, so it is probably made up mostly of the 10% that’s less than 500 micron. And this material could be explosive. Not only that, but if that 10% of the material particle size distribution has a significant amount of dust less than 100 micron, this could very well be the dust cloud which is much more likely to be explosive. And since the smaller the particle size the better the chance of the material being explosive, your dust cloud could be explosive dust. This would then float in the building and layer the surrounding equipment or rafters with explosive dust.

Now looking at the material leaving the grinder, even though it tested as not explosive this is the material on the conveyer or that was bagged. If the grinder feed creates a dust cloud then this will again be the finer dust. So while the majority of your material is around 200 micron, there is a small portion (now much greater than the initial amount that was less than 100 micron) that is very fine. And again, this portion of the dust is the dust that is creating the dust clouds at the exit of the grinder and in the bagging section.

So when you are collecting dust to see if it is explosive, be sure to collect the material that is pertinent. You should try to collect dust that is actually forming a cloud to make sure it is explosive and not lump it in with material that won’t form the cloud. If you have an existing baghouse or cartridge collector, use the material that is collected in the dust collector for testing.

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Now that it is spring, it’s time to start thinking about summer shut down! If you are planning on doing maintenance on your dust collection system now is the time to order your parts.

If you are changing bags also look into doing the following:

1. Pull your airlock off and perform any needed maintenance on it (replace bearings, change out rotors or plate, replace Vacu-Valve sleeves, etc.)
2. Have someone check your exhaust fan a few weeks before shutdown so that if the fan needs rebalancing or bearings replaced, you can schedule it during the shutdown.
3. Inspection of your baghouse a few months before shutdown so any damage in the housing, bad air valves, tube sheet, etc. can be replaced during the process.
4. Inspect the ductwork and look for holes and dust buildup. Make sure dampers are working.
5. Look into installing a cyclone pre-filter to
    
   1. Increase filter life
   2. Decrease compressed air usage
   3. Collect dust before contamination in the filters
6. Inspect explosion protection equipment and have any chemical isolators/suppression equipment maintained. Be sure to have the clearance of the rotary valve measured to be sure it is still in compliance with NFPA requirements.
7. Schedule a Dust Efficiency Clinic to evaluate the system performance so any modifications can be installed during plant shutdown.

Doing the above will help you revitalize your dust collection system and make sure you get the best possible performance out of it.

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A dust collection system consists of four major components. The pickup hood, ductwork, dust collector, and exhaust fan. For the system to operate efficiently all four components much be sized and used correctly. Unfortunately, one of the main components (the hood) is often overlooked. The hood design is crucial for the operation of the dust collector system. And without the proper hood design, your dust collector will not provide the dust pickup required for the safety of the equipment and workers.

The hood should be designed so that it will capture the dust without letting dust escape. This can often be difficult as the hood will need to be designed to pull air from all the areas generating dust while also provide the required access of the operator / machine.

Using the wrong hood can cause:

• Dust to escape the hood, thereby causing health, safety, and maintenance issues.
• Too much dust is captured, removing product or components from the process.
• Too much air is used, increasing the system size and cost.

When you are looking to install a dust collector system, pay attention the hood design of the system. Spend time selecting the proper hood for the application and don’t just go with the least expensive hood, as this could cause your entire dust collection system to fail at its job.

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