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Making Sense of Dust Collection Technology

June 21, 2019
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Vertical cartridge dust collector
Vertical cartridge dust collector
Bin vents
Bin vents

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Selecting the dust collector for your application can be an overwhelming and confusing task with all the different types of technology to choose from. Let’s review the different types of dust collectors and baghouses and the common uses for each of them.

Pulse Jet Technology

High-Pressure

A high-pressure pulse jet baghouse utilizes 90-100 PSIG clean, dry, and oil-free compressed air for its cleaning energy. The source of which is typically from a facility’s plant air system or a dedicated air compressor. The baghouse is controlled by a solid-state timer to sequentially energize remote pilot solenoid valves that are plumbed to corresponding diaphragm valves that are mounted on a compressed air header and plumbed to blowpipes complete with orifice nozzles positioned directly over each filter. The pulse air exiting the nozzle passes through a venturi and enters the inside of the filter, purging collected dust from the exterior surface of the filter media.

Medium-Pressure

A medium-pressure pulse jet baghouse utilizes a positive displacement rotary lobe blower to supply cleaning air at 10-12 PSIG. The medium-pressure pulse jet operates like the high-pressure except that the remote pilot solenoid valves are plumbed to corresponding large double diaphragm valves mounted on a compressed air reservoir and plumbed to blowpipes complete with large orifice nozzles positioned directly over each filter.

High- and medium-pressure pulse jet units can be manufactured in round (cylindrical), square, or rectangular housings with either bottom or top filter media access designs. Top loading provides clean side access for media replacement. The walk-in clean-air plenum is ideal for regions that face inclement weather. Pulse jets can also be designed to accept cage supported felt filter bags or pleated filter elements.

Common Industries: Both high- and medium-pressure pulse jet baghouses are ideal for tough process dust collection industries such as cement and mining, utility, recycling, and powders and bulk solids.

Common Dust: Can include high-temperature, sticky, hygroscopic dusts like clinker, limestone, tire and rubber fines, sawdust, and seed dust.

Common Applications: nuisance dust, venting dryers, loading and packaging lines, grinding, and central vacuum systems.  

Reverse Air Cleaning

Low-Pressure

A low-pressure reverse air dust collector utilizes a high-pressure centrifugal blower/fan to supply cleaning air at 15 in. W.C. (approx. ½ PSIG). This fan is plumbed to a rotating manifold comprising of two asymmetrical cleaning arms complete with high velocity venturi nozzles positioned over the filters. The high-volume, low-pressure air exiting the nozzles enters the inside of the filters, purging collected dust from the exterior surface of the filter media.

Medium-Pressure

A medium pressure dust collector utilizes a positive displacement rotary lobe blower to supply cleaning air at 7½ PSIG. The collector is controlled by a solid-state timer to sequentially energize a pilot solenoid valve plumbed to a secondary double diaphragm valve and primary diaphragm valve assembly mounted on a compressed air reservoir tank. This tank is plumbed to a rotating manifold comprising two asymmetrical cleaning arms complete with high velocity venturi nozzles positioned over the filters. The pulse air exiting the nozzles enters the inside of the filters, purging collected dust from the exterior surface of the filter media.

Manufactured in round (cylindrical) housings with top filter media access utilizing either cage supported felt filter bags or pleated filter elements.

Low- and medium-pressure dust collectors are the preferred choice when plant air is unavailable, or a dedicated air compressor is not desirable. Reverse air cleaning technology is a good option in remote or Common Industries: Both low- and medium- reverse air dust collectors are ideal for tough process dust collection industries such as agriculture and ethanol, paper and wood, and aggregates.

Common Dust: Can include DDGS, paper trim, limestone, wood, grain, and seed dust.

Common Applications: Nuisance dust, classifier ventilation, receiving and load-out system.  

Filter Media for Dust Collectors

Bag Filter Media

The proper selection of filter media is necessary to ensure low pressure drop, long filter life, and high filtration efficiencies. There are a wide variety of felted filter medias available (see fiber selection chart). Surface treatments such as singing, glazing, and ePTFE membrane are also commonly utilized to enhance filter performance.

Pleated Element

Pleated filter elements are generally available in a spun bond polyester with a standard temperature design limited to 225°F and an available upgrade to 265°F. A pleated filter element utilizing a self-supported pleatable Aramid needled felt is also available, good to a maximum temperature of 375°F.

Vertical Cartridge Collector
A vertical cartridge dust collector utilizes 90-100 PSIG clean, dry, oil-free compressed air for its cleaning energy. The source of which is typically from a facility’s plant air system or a dedicated air compressor. The collector is controlled by a solid-state timer to sequentially energize remote pilot solenoid valves that are plumbed to corresponding diaphragm valves mounted on a compressed air header and plumbed to blowpipes complete with diverging, multi-orifice nozzles positioned directly over each filter. The pulse air exits the nozzle and enters the inside of the cartridge filter, purging collected dust from the exterior surface of the filter media.

Manufactured in square and rectangular housings with side filter media access utilizing pan and core supported pleated cartridge filter elements.

The cartridge filter elements are generally available in a cellulose/synthetic blend media with a standard temperature design limited to 180°F or a spun bond polyester with a standard temperature design limited to 200°F and an available upgrade to 250°F. A pleated filter element utilizing a self-supported pleatable Aramid needled felt is also available, good to a maximum temperature of 350°F. Surface treatments such as fire retardants and nano-fiber on cellulose/synthetic blend media as well as Oliephobics to ePTFE membrane on spun bond polyester are also commonly utilized to enhance filter performance.

(see table)

Common Industries: Cartridge collectors are ideal for light-duty process dust collection industries such as agriculture, powder bulk, and automotive.

Common Dust: Can include rice and seed, chemical, and paper dust.

Common Applications: weld fume, grinding, abrasive blasting, nuisance dust, secondary dust collection, re-bagging operations, and aspirator.  

Bin Vents and Spot Filters
A bin vent is a configuration of a pulse jet baghouse or cartridge filter collector that has the same features and benefits. They do not typically incorporate a hopper, but instead are mounted on top of dust generating equipment such as silos, mixers, scale hoppers, and mechanical conveyors. Instead of discharging the captured dust into a hopper, when using a bin vent, the pulse-cleaned dust falls directly back into the process equipment it has been mounted to. The filtering system can be designed to use bags and cages, cartridges, or tailored to fit your application.

Inlet Design
The proper selection of the dust collector inlet design will impact the overall performance of the dust collector. A high-entry inlet with staggered channel baffles is ideally suited for non-abrasive and light-density dusts at light to moderate dust loadings. Whereas hopper or housing sidewall inlets with impingement baffles located below the filter media may be suitable for mildly abrasive dusts. On round (cylindrical) collectors, tangential inlets with vortex breakers or involute scroll inlets with particle deflector cones located below the filter media is the preferred choice for abrasive dusts or moderate to heavy dust loadings.

Deflagration Venting and Explosion Protection
When handling combustible dusts, the dust collector and dust collection system must be designed and supplied to include the appropriate deflagration venting and/or explosion protection and isolation equipment in accordance with the latest National Fire Protection Association (NFPA) standards and authority having jurisdiction (AHJ).

If your air quality goals are to achieve certain filtration efficiencies, meet NFPA, OSHA, or EPA standards and requirements, or to have equipment that is easy to maintain it’s important to keep those in mind when selecting the best dust collection technology for your process. If a standard dust collector or baghouse cannot meet your air quality goals, look for a manufacturer that can design and engineer a dust collection system that will meet your objectives.

Tracy Janssen is vice president air pollution control, CAMCORP (Lenexa, KS). CAMCORP dust collection and bulk material handling solutions can be standard or modified to fit any application. For more information, call 877-226-2677 or visit www.camcorpinc.com

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