Industrial Dust Collector Methods
Industrial Dust collectors are designed to be used in most industrial processing establishments. They are often employed to either recover valuable granular solid or powder from process streams and they can also be used to remove granular solid pollutants or industrial dust from exhaust gases and work environments.
This article will talk about industrial dust collectors and everything that you need to know before installing one in one of your manufacturing facilities.
What are some Industrial Dust Collector methods used nowadays?
There are plenty of different ways for dust collection that buyers can choose from. With each of them having their own strengths and some more suited for certain applications than others.
Cyclone separators employ the use gravity and an air vortex to create separation of particles from gas streams. The air is then directed through a cylinder case which will be spun in a rapid manner. This will create a strong enough centrifugal force that will draw the particles to the wall of the cyclone. After the PM hits the wall, it will slow down and lose velocity and lift. This will cause it to fall into a collection hopper at the bottom of the machine.
These devices are often cheaper, rugged devices that have basically no moving parts and will require very little maintenance from the facility workers. However, they will not be very effective at capturing very fine industrial dust, but have decent efficiencies at greater than 90% for larger particles larger than 5µm. The cyclone is very ideal as the first stage collection device or what are commonly called as precleaners. It is used to lighten heavy dust loads before the use of more expensive pollution control devices. Some possible uses of it are as baghouses, or electrostatic precipitators which will have higher collection efficiencies. The cyclone can also deal with a larger range of temperatures and pressures while also catering to plenty of media types. Albeit the sticky materials or moist particulate may not be as compatible. This is because they have a tendency to stick to the cyclone walls. The cyclones have been used by large industrial gas streams to small workshop environments.
Electrostatic precipitators or better known as ESP or electrostatic air cleaners is a collection method that uses electrostatic forces to separate particulate matter(PM) from the exhaust gases. At its core, the particles will move through a region where installed electrodes will induce an electric field to charge dust particles. This will consequently attach themselves to a collection surface to gather them up. After it completes, the surface is then washed, rapped, or vibrated to remove the particulate and collect it in a hopper.
The ESP commonly used today are considered to be highly efficient. They can also remove dust and smoke from large containers with big volumes and airstreams with minimal interruption of gas flow. However they can be normally quite expensive, but will cost much less to operate and maintain compared to other methods. The recorded collection efficiency from most tests of electrostatic precipitators can be largely dependent on the electrical properties of the particulate being collected. The more common ESPs nowadays which are properly designed can reach collection efficiencies beyond 99.9%.
When using media filtration, devices can be used to screen or filter to physically separate particles from gas streams. This method of dust collection has its own set of advantages and disadvantages.
Media filtration advantages include versatility and flexibility for its many applications. It also boasts high efficiencies for PM collection and is especially effective for smaller particles while maintaining cost-effectivity. However, to achieve this feat the devices have to be properly designed and maintained properly. The reason why it can be used at minimum expense is because of its modular or compact design which also allows for convenient assembly. And finally, it can collect other pollutants by applying specially designed coatings to the filters.
Despite the advantages, there are some limitations that have to be taken into account such as the one posed by high temperatures and corrosive chemicals. Media filtration does not bode well when confronted with significantly higher amounts of either. It is also not well suited for very high dust loads that could be a problem for mass production. And to top it off, it requires frequent maintenance that could add to the operational expense. It has been known that this method will leave large footprints in the case of baghouses and most industrial media filters with automatic cleaning sequences. And finally, this method can be hazardous as it has the potential for fire or explosion especially for fabrics in dry environments.
The baghouses, which are also called fabric dust collectors or fabric filters, are devices that use multiple fabric filter tubes or bags that then captures or separate dust and other particulates. While the gas streams are directed through these bags, a thick layer of particulate which is called the industrial dust cake will be collected on the fabric and is widely responsible for most of the filtering. These bags are intermittently or continuously being cleaned by either shaking them, reversing the airflow, or subjecting them to pulses of air.
When comparing baghouses to other types of air pollution control or APC equipment. They are often considered to be incredibly versatile and can be remodeled to fit almost any dust producing need by simply varying size and bag types. They are also quite efficient and when properly designed and maintained, they can are also rugged enough to handle more demanding applications. But, they will normally need a lot of maintenance and monitoring and a relatively dry environment to operate effectively without problem. The applications for these will however be limited to certain operating temperatures and chemical conditions. This is because of the nature of the filter fabrics and operating environment.
Another option is to use cartridge dust collectors which use perforated, cylindrically shaped metal cartridges lined with a pleated nonwoven filtering media. After installing it one end of the cartridge will be sealed off. And then the open end will used for the clean exhaust. Not dissimilar to a baghouse, this method of filtering is accomplished by forcing the gas stream through the cartridge. Most cartridge collectors will be compatible with a lot of reverse air or pulse jet cleaning techniques
Even though they are no longer as widely employed as they used to, the cartridge dust collectors are especially suited for specific applications that would involve special shaped and certain sized dusts. This method is generally effective for granular shaped & less than 50 microns and low grain loading levels less than 5 grains per cubic foot. Cartridge collectors are also quite satisfactory for collecting industrial dust that require a small amount of flexing of the media during the cleaning process. The pleated design allows for a greater amount of filtering area which will occupy a smaller space. As a consequence the air-to-cloth ratio, pressure drop, as well as filter cartridge size are considerably reduced. The applications of this method includes grinding or sandblast applications, welding fumes, laser and plasma cutter fumes, graphite, pharmaceuticals, and fine chemical powders. Cartridge collection also applies to other applications aside from the ones mentioned.
Industrial vacuums which are dust collection devices which use vacuum suction can also be used. Essentially, it pulls air in for filtering during operation. When activated, the air streams are pushed through a media filter located inside the casing. It will then be pushed out through a discharge outlet. The vacuums can then be incorporated fabric bags, envelopes, or cartridges as filters depending heavily on the media being collected as well as the design of the device.
The way the industrial vacuum differs to the baghouses and cartridge filters, is that they are typically portable. They are single-filter devices and can be operated manually if desired. They are often employed frequently whenever a spill occurs and needs cleaning. It is also suitable for general cleaning, and the removal of fine powders and toxic or hazardous media.
Other filter-based dust collectors that are available in the market can come in a number of other different forms. The collector booth is one of them which are simply filter units which require no ductwork, and allow the worker greater freedom of movement. These are often portable which allows for a more versatile dust collection operation. And finally, the downdraft which are tables self-contained portable filtration systems can be used to remove harmful particulates. It can then return filtered air back into the facility, requiring no external ventilation.
The wet scrubbers are industrial dust collection devices that will employ the use of a liquid, which is often water, to capture and remove pollutants. Using the process of agglomeration, adherence, or encapsulation, these devices will merge dust particles with the scrubbing liquid to multiply their sizes and mass and make collection of the particles easier. The moist particles will then be gathered through a separation or filtering process that is based on the type of scrubber. The common types of particulate scrubbers that can be bought in the market today include gravity spray towers, cyclones spray chambers, impingement scrubbers, packed bed scrubbers, venturi scrubbers, and many others.
The most common wet scrubbers, most notably venturi scrubbers, will normally have quite a high particulate collection efficiencies compared to other methods. The reason for this is due to the use of liquids like water. Wet scrubbers also have the ability to absorb gaseous pollutants such as acid gases which makes it especially useful for chemical facilities. However, there are also other uses of water that can be expensive which requires the devices to be built from more costly, corrosion resistant materials. The industrial dust that is gathered has to be more expensive to handle than dry solid and may be too contaminated to recycle.
There are some advantages in using wet scrubbers during as a dust collector method. For one, it can handle flammable and explosive dusts with little risk of having any accidents. It also provides gas absorption and dust collection in a single unit which is convenient considering how gas absorption becomes a main problem in dust collector operations. To limit any spikes in hear it provides cooling of hot gases which allows for further safety. Collection efficiency can be varied which allows versatility during dust collection. And finally, corrosive gases and dusts can be neutralized during operations.
Despite many benefits, there are also some downfalls in using wet scrubbers. The main one is the high potential for corrosion problems which is difficult because of the high cost of part replacement. Another is that the collected particulate may be contaminated and unrecyclable which means that the industrial dust will have to be manually removed and disposed of. While wet scrubbers boast high efficiency protection against freezing is still required. There are certain streams that may require reheating to avoid visible plume. And the disposal of waste sludge can be very expensive which can add up especially since constant disposal is required.
Industrial Dust Collection Categories
Particulate collectors can also be grouped based on the type of operation it does.
The more common mode is ambient units which are designed to continuously filter airborne particles as air circulates through an environment. They are employed in applications where there is no defined source of the dust creation/pollution or where the use of proper ducts and source-capture arms is limited. They are also preferred for applications where a source collector does not provide sufficient capture of small particles.
On the other hand source collectors are designed with ducts and arms to capture and filter air at the source. These dust collectors can be either stationary or portable units depending on the application required.
There are many more methods out there designed for dust collection that may be better suited for your facility. The important thing to note is to always refer to experts before investing in pricey equipment to ensure the efficient operation of the facility you are handling.