Lesson 1

Baghouse & Dust Collection System Overview

Baghouse & Dust Collection System Overview

Welcome to lesson one, where you will learn:

  • The basic function of a dust collector
  • The different types of dust collectors, including cartridge collectors, baghouses, cyclone collectors, and where they are uses.
  • The major components and sub-systems that make up a dust collection system.

Welcome to our series of video lessons for Baghouse 101.

In this lesson we’re going to talk about the different kinds of dust collectors that are available and what each one is used for. Dust collectors fall into several categories:

1. Mechanical Dust Collectors: These are devices like cyclones, knockout boxes, other physical devices that physically remove the dust from the air without using any kind of filters. These are often used as pre-filters, or they’re used in applications where they’re really just trying to get rid of the majority of the dust, but they’re not efficient enough to use as the only method of dust collection.

2. Specialty Dust Collectors: These include wet dust collectors, electrostatic precipitators, and scrubbers, which are used in very special applications. This can include collection of extremely hot, explosive or corrosive materials or at some large power plants.

3. Fabric Filter Dust Collectors: This category includes the majority of dust collectors that you will see across all industries. Most commonly, you will see baghouses and cartridge collectors.  This is the most common style of fabric filter dust collector are baghouses. They’re called baghouses because they use filter bags. You will occasionally run across other types of filters like panel filters or envelope filters, which are just different shapes of filters that are used in other kinds of baghouses. But here in North America, the most common style is a bag shaped filter.

Types of Baghouses

There are several different types of baghouses, depending on the type of cleaning system they use. 

The oldest style is a shaker dust collector where the bags are physically shaken using a motorized mechanism (or in some really low-tech versions, using a manual handle) to remove the dust. These are generally legacy units because this form of cleaning is very inefficient, and it requires you to shut down the airflow for it to work. 

The second type of baghouse is called a reverse airbag house. In this type of dust collector, the air flow to a compartment is stopped and a separate reverse air fan blows air back into the baghouse to clean the filters off. This kind of cleaning system is really only effective in very large baghouses with multiple compartments, so you see them in large applications like power plants and cement kilns for steel mills.

The third type is the most common and that’s the pulse jet baghouse. In a pulse jet baghouse, the filters are cleaned using compressed air while the baghouse is running. There is no need to interrupt the airflow so you don’t need to shut off the baghouse fan in order to clean it. Because of this, pulse jet baghouses are by far the most widely used and you will see them across all industries, and from very small little bin vent collectors up to large utility size baghouses.



There is one slight variation that you may also encounter, which is called a medium pressure reverse air baghouse (sometimes called rotating arm baghouses). These are large cylindrical units with a rotating arm that blows air back into the filters at medium pressure, around 10 psi. Functionally it works very much like a pulse jet baghouse for cleaning filter bags. This type of collector is typically only used in certain industries, such as sand or grains and food products. They’re not quite as powerful cleaning as the pulse jet baghouse so we don’t use them as much. 

One other variation of the pulse jet style that’s very widely used is the cartridge collector. A cartridge collector is essentially a pulse jet baghouse but uses cartridges instead of bag filters. They are very effective in certain applications because they can pack in much more filter area into the same space. When you have a lot of airflow but lighter dust loads, these can be very cost effective, and for that reason they’re widely used across a lot of industries.

In summary, we have many different kinds of dust collection systems available, some older and some more specialized, but the most common being the pulse jet baghouse. Regardless of what your needs might be, here at Baghouse.com we are a full-service provider of all different kinds of dust collection systems and we have the right system for you.


Mechanical Dust Collectors: What are they? What do we use them for? A mechanical dust collector is simply a dust collector that doesn’t have any filters

The most common type of mechanical separator is a cyclone. But we also have things like classifiers, knockout boxes, and other kinds of equipment that work in a similar manner. The way they work is (a) by causing the air to slow down, (b) by spinning the air, or (c) by causing the air to pick a torturous path or to collide with a blunt object like a plate, causing the particles that are suspended in the air to fall out without using any filters.

In this way, they’re able to remove a large amount of dust from the dust stream. In most cases, 90% of all dust above 10 microns can be removed very easily with a cyclone.

In other cases, high efficiency cyclones can even get down to 4-6 micron particles, and efficiencies up to 95%. However, this is still not enough dust removal to allow you to exhaust the air out to the atmosphere in most applications in modern times. So, for that reason, they’re not widely used anywhere as the only dust collector on a system. You may find them in a few legacy applications like this, but they almost certainly don’t mean modern code now. 

So, what are they used for today? There a couple of different uses. The most common use is as a pre-filter for another dust collector. It’s very common to see a cyclone paired with a baghouse downstream. The reason we would do this is because the cyclone can remove the vast majority of the dust coming in and then leave just the fines with much lighter load for the baghouse. This allows you to protect the baghouse filters and extend their life, and it also can be cost effective in certain applications because it makes the baghouse work less.

You might also use cyclones in an application to remove certain sizes of dust in different places. You might have a cyclone that’s been finely tuned and designed to remove a certain range of particle size, say 20 to 100 microns in size, and then whatever is either larger or smaller than that may continue on to the baghouse to remove. This can be useful when you’re sorting or trying to filter out waste material from reusable product.

Because of that ability to remove certain particle sizes, mechanical collectors are also often used as what we call spark arresters or spark traps. This works because for a spark or an ember to stay hot, it has to be a certain size to continue burning. So often we employ some kind of spark trap that is essentially a horizontally installed cyclone to spin the dust stream around to break up the larger pieces that are big enough to be on fire or be an ember so that by the time they reach the baghouse they will have burned out. In this way, it prevents sparks and embers from getting into the baghouse and causing a fire or damaging the filters. It is common to find cyclone mechanical drop out boxes or knockout boxes, especially on larger systems.

Thanks for watching. If you enjoyed this video or have a suggestion for another topic you’d like to see us discuss here at Baghouse.com, please leave us a comment below. You can also sign up to receive access to exclusive content.

Whether you’re designing a new system, looking for help with a technical problem, or just need some replacement parts or service on your dust collector, please reach out to us and let us know how we can help. Thanks for watching!

Let’s review the basic components of a dust collection system. First, you’ll notice I said dust collection system not just dust collector. That’s because the dust collector is just one part of the overall system that we need to consider. 

The first part is actually the ductwork system itself. The ductwork for a dust collection system can have multiple pickups or drop points. Sometimes it can just be one. These usually take the form of either some kind of hood over a dust source, or a connection from a piece of process equipment, fitting directly into the machine or apparatus. Regardless of how it connects, we then have our duct branches which come together and form the ductwork trunk line or the main branch of the ductwork, which then goes back into the dust collector. 

This bottom cone section of a dust collector is what we call the dust collector hopper. Above that, we have what is called the dirty air plenum, or the dirty side of the baghouse. In this particular style, we have the tube sheet that is about a few feet below the top roof and this metal plate has holes in it that then hold the filter bags. Now as the dirty air comes in, it is routed into and through the filters, leaving the dust in the dirty side. Only clean air comes up and out into this section up here above the tube sheet. For that reason, we call this section of the dust collector the clean side of the baghouse or the clean air plenum.

On the other side, we have our connecting ductwork to the baghouse outlet which routes air down to our system fan. From our system fan, we then have some kind of exhaust stack that either lets the air exhaust out or in some instances we return the air back to the building. Sometimes when we return air back to the building, we may also have a HEPA after filter that’s placed after the fan. This is to capture any leaks that might have gotten by the baghouse filters when they’re running.

If we go back to the baghouse, you’ll notice in our hopper section, at the bottom we have the dust collector discharge. This is the bottom of the hopper where the dust is removed from the system. There needs to be some kind of air lock here to prevent open air from getting pulled in from outside. We can have a couple different options here. The simplest is a mechanical or manual slide gate. What’s more common is some sort of airlock. This would be most commonly a rotary airlock, but it could also be tip valves or some other kind of air lock that allows dust to be removed while maintaining an airtight seal.

Below the discharge device, whatever it may be, you’ll usually have a couple of different options. The simplest is simply to discharge the dust into some kind of bin or bag like a super sack. It could just dump into here and when this is filled, somebody removes it and places a new one underneath. Another situation that we might have is the dust is dropped down into some sort of pneumatic conveyor that will then blow the material away, perhaps to another bin or storage silo and be used somewhere else in the facility. The same thing goes for a mechanical screw conveyor or auger. Dust drops into it and then a screw carries the dust away either to be disposed of or reused somewhere else.

There are also smaller parts of the dust collector to consider, which vary on different kinds of dust collectors. For example, onn a pulse jet baghouse we have other parts like the pulse valves, air header, blow pipes, etc. Different cleaning systems will have different components but some of the smaller things you’ll see on all baghouses will include some sort of differential pressure gauge or monitoring device and you’ll see these two air tubes, one just above the tube sheet and one just below it. These will be connected with airlines down to a gauge, usually a magnahelic gauge, or sometimes it’s directly on a control board that can read differential pressure. This is the most important reading for your Baghouse operation, so it’s always going to be present on any kind of dust collector you have. You may also have different kinds of sensors for temperature. You may have a sensor that tells you if the hopper is filling with dust, or you may have other things like heaters, vibrators on the hoppers to keep them clean, and other accessories like these.

Thanks for watching. If you enjoyed this video or have a suggestion for another topic you’d like to see us discuss here at Baghouse.com, please leave us a comment below. You can also sign up to receive access to exclusive content.

Whether you’re designing a new system, looking for help with a technical problem, or just need some replacement parts or service on your dust collector, please reach out to us and let us know how we can help. 

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