Types of Industrial Dust Collectors

Industrial dust collector systems prevent harmful and bothersome dusts and fumes from settling on surfaces, causing injuries to employees or equipment damage. They help facilities comply with major regulatory bodies like OSHA and NFPA and reduce worker health risks.

There are many types of industrial dust collection systems that serve different needs. Choosing the right one depends on facility size, dust type, and other factors.

Electrostatic Precipitators

ESPs remove airborne pollutants from process exhaust before they are released into the atmosphere. They are used to protect employees from harmful dust, fumes, and mists and keep facilities in compliance with local and federal air pollution regulations. ESPs can be constructed in a variety of designs and sizes to fit different facility needs. The most common industrial dust collector type of ESP is the plate-wire design, which includes a set of parallel plates and wire electrodes with a high voltage electric field that attracts and collects pollutants. The electrostatic force attracts a negatively charged particle to positively-charged plates, which are then removed and disposed of in a bin or hopper at the bottom of the device. This type of ESP is also called an electrostatic precipitator, an electrostatic air cleaner, or an electrostatic precipitation system.

Depending on the design of the device, it can produce high collection efficiency up to 99.5% for PM2.5 particles in certain conditions. This efficiency depends on the specific collection area of the device, dust resistivity, gas temperature, and other factors.

Electrostatic precipitators separate soot, ash, and dust particles from the flue gases that are emitted by industrial chimneys. These gases are poisonous to humans and the environment, and the ESP’s electrostatic forces charge these particles so they are attracted to negatively-charged plates within the device. When the plates are periodically rapped or rinsed, the particles are collected and removed from the environment.

Wet Scrubbers

Wet scrubbers bring a gas stream and its contaminants into intimate contact with a liquid, encapsulating large dust particles in the water droplets. They are typically used to control combustible metal dusts. They also serve to remove odors, fumes and gases from spray drying operations.

The scrubbing process requires little energy and can be conducted at temperatures higher than those for baghouses or ESPs. However, the high volume of slurry can result in a high pressure drop. This can increase operating costs, resulting in a limited range of applications. In addition, corrosion can be a problem in wet systems.

Small particles in the exhaust stream can be collected by impaction or diffusion. Impaction is the more common method, where small particles are “bumped” by gas molecules and then collect on a surface or collide with other small particles. Diffusion is a more random process, where airborne particles move in various directions and eventually collide with a droplet. In either case, collection efficiency increases with a decrease in particle size and a decrease in liquid-droplet size.

A scrubber may also be used to remove volatile organic compounds (VOC). These are often associated with industrial processes, such as petroleum refining, wood processing and textiles. VOCs are flammable and can pose health risks. Scrubbers can be used to minimize VOC content in a facility’s industrial air, protecting workers and ensuring compliance with local and state emissions regulations.

Pleated Bags

Baghouses are a common type of dust collector that use envelope style bags. Rectangular multi-pocket fabric bags collect the dust on the outside, supported by wire frames or porous foam to prevent collapse and are discharged by an arm that knocks or shakes them, releasing the collected dust into a hopper below. These types of systems require off-line cleaning at air velocities below 250 – 270 FPM and have an air to cloth ratio of 2.0 – 3.0:1.

Upgrading to pleated bags can increase the air velocities through a baghouse while maintaining a lower pressure drop versus conventional bag and cage filters. This allows a single dust collector to be used for multiple applications instead of purchasing new equipment and provides energy savings from reduced system power usage and improved air quality.

Using pleated filter elements can also improve the lifespan of existing bags, reducing maintenance costs and downtime by eliminating blockages. This is because pleated filter elements have more surface area for better dust loading and they’re usually shorter in length, reducing the opportunity for abrasion caused by high-speed abrasive materials.

Pleated filter elements are made from a durable spun-bonded polyester media and are available in both top access and bottom access designs to fit traditional baghouses. The wide shallow pleats provide significantly more surface area per element compared to a standard polyester bag and can handle high dust loads. The increased surface area enables lower energy use and operating pressure drop for improved air flow, healthier emissions, longer element life and reduced maintenance costs.

Pulse Jets

As its name implies, a pulse jet uses a series of spring-loaded shutter-type valves that alternately admit air or close it to produce thrust. The design ingests stalled air and ignites it in front of the combustion section, with the engine exhausting through its rear nozzle. The resulting thrust is what propels the engine forward.

Pulse jets require no compressed air for operation and can produce some thrust even at zero speed (as opposed to ramjets, which require auxiliary power to accelerate). They also have good fuel efficiency and top speeds that grow as the aircraft flies. They tend to generate a lot of noise, however, which limits their use to low-cost, pilotless drones.

Wave Engine, a startup in New Zealand, recently conducted a successful test flight of one of its new pulsejets using a industrial dust collector manufacturer conventional takeoff and landing configuration with a scaled-down version of a German buzz bomb or V-1 missile body. The drone used a standard turbine engine for taxiing onto the runway and taking off, but switched to its pulsejets shortly thereafter.

The design looks like a bottle shape with a hemispherical cap attached at the top, with the combustion section formed by an inner section of bottle-shaped walls with a tulip ‘waist’ that gently narrows. The design appears to be based on the research of Joseph G. Logan, a well-known pulsejet researcher and designer of the Project Squid gas turbine. He investigated a number of capped-tube designs and settled on this layout, which is designed to self-sustain without the aid of pressurized air.