Types of Dust Collectors and Their Uses

Construction sites, manufacturing plants, and other industries usually have a lot of dust particles, either airborne or lying around on the floor.

The removal of such particle matter requires a dust collector.

To see the difference that a dust collector can make in the amount of dust generated, visit “Industrial Dust Control Systems”.

Types of Dust Collectors

A dust collector can be of many types. Let us go through the infographics below to see the different types –

  1. Inertial Separators
  2. Fabric Filters
  3. Wet Scrubber
  4. Electrostatic Precipitators [ESP]
  5. Unit Collectors

Each one of the above-mentioned dust collectors is specifically designed for a particular use. Let us proceed to try and get to know each one of them a bit better.

Dust_collector

Source: Wikipedia

1. Inertial Separators

Inertial separators purify the air by separating dust particles from the gas stream. This is done by combining inertial, gravitational and centrifugal forces.

As these forces work on the gas stream, the dust particles are moved to a spot where such forces are minimal. The gravitational force exerted on the dust particles then makes them enter a hopper.

This hopper is used for temporarily storing the dust particles.

There are three main types of Inertial Separators –

Settling Dust Collectors.

A settling dust collector separates dust from an otherwise dirty air stream with the help of a large box that is referred to as a settling chamber.

As the settling chamber is quite spacious, a dusty air stream that rushes into it finds itself being slowed down considerably when in the chamber.

The gravitational force working on the dust particles settles them down from this slow air stream. This effectively separates dust particles from the air stream.

Commonly used in the cement industry, a settling chamber collector requires an ample amount of space for the particulate matter to settle and distill properly.

Baffle Dust Collectors

A baffle dust collector is so named for the flat plate or baffle plate that is used. Initially forced to move downwards, the dusty air stream is made to strike a baffle plate which causes it to change direction.

The re-directed air stream is then made to turn in an upward direction, at a 180 degrees angle. Rapid changing of directions slows down the air stream considerably.

With the slowing down of the dusty air stream, the heavier dust particles are acted upon by the gravitational force which forces them to either settle down or strike the baffle plate.

These heavier dust particles, mopping up other comparatively finer particles of dust, then slide into a hopper.

Centrifugal Dust Collectors

These are also known as cyclone dust collectors. A centrifugal dust collector purifies the air by creating a centrifugal force resembling a cyclone, which can also be equated to a whirlpool or water rushing down a drain.

In a cyclone dust collector, the centrifugal force is created when the dust-laden air enters at the top of the collector which is cylindrical in shape.

As the dusty air stream enters at an angle, it is spun with great force in a downward direction. Resembling a vortex or whirlpool, the dust particles are thrown towards the walls of the collector. These particles then slide downwards into the hopper.

To be effective, the centrifugal force generated in a cyclone dust collector must be powerful enough to eliminate all impurities from the air stream.

To see how a cyclone dust collector works, check this video out –

2. Fabric Filters

Also commonly known as a baghouse, a fabric filter can remove very small particulate matter that stays suspended in the air for a longer period of time, can lodge much deeper in the lungs when inhaled, and which are the most difficult for the human body to eject.

A filter dust collector uses a screen filtration system to remove dust particles from the air. The air stream to be cleaned is made to enter the baghouse that contains a screen made usually from felted cotton.

While the gas passes through, the dust particles collect on the surface of this screen. Fabric filters are cost effective and have a high rate of efficiency in effectively cleaning out fine dust particles.

Using a minimum of 6 felt bags or a maximum of 900, baghouses are widely used in many processing and manufacturing plants.

It is the technique employed for the removal of the collected dust that leads to the classification of fabric filters into the following varieties – Reverse Air, Cartridge Collectors, Pulse Jet, Shaking and Sonic collectors.

3. Wet Scrubber

Simply put, a dust collector that uses liquid to separate dust particles from an air stream is called a wet scrubber. Typically, water is made to come into contact with the dusty air stream.

The more the contact, the greater the efficiency of dust removal.

While there are many kinds of wet scrubbers, the basic principles followed in each are the same –

  1. Gas-dehumidification
  2. Gas-liquid contact
  3. Gas-liquid separation

While the cleaned gases are passed through demister pads that eliminate mist from the air stream, dust that settles is removed in a drag chain tank or clarification unit.

Wet scrubbers are ideal in situations where the dust particles are combustible. Coming into contact with water, the combustible dust particles are denied oxygen, thereby doing away with the risk of spontaneous combustion.

4. Electrostatic Precipitators [ESP]

A kind of dry scrubber, an electrostatic precipitator is a filter that makes use of static electricity to remove suspended dust particles from the air stream.

Commonly used at power stations, electrostatic precipitators can remove ash and soot that is got when fossil fuels such as oil or coal are burned to make electricity.

The mode of operation employed in these dust collectors is quite simple. The air to be cleaned is passed through two electrodes that can be in the form of metal bars, plates or wires.

One of the electrodes has a high negative charge, as the dust-laden air passes through this electrode, the dust particles in it get a negative charge.

Traveling through the pipe, the dusty air then encounters another electrode that contains a high positive charge.

Based on the simple principle that unlike charges attract, the negatively charged dust particles get attracted to this electrode and stick to it.

Usually used in coal-burning plants, the ash, and soot collected from the air is referred to as fly ash.

5. Unit Collector

Handling dust at the source itself is what sets apart Unit Collectors from the other kinds of dust collectors.

The two basic types of Unit Collectors are – Fabric Collector or Baghouse dealing with small dust particles or fine dust, and Cyclone Collectors that are better equipped to handle the coarser dust particles.

How to Select the Most Appropriate Dust Collector?

With the many kinds of dust collectors available in the market to choose from, narrowing down the search requires addressing parameters such as –

  • Kind of application that the dust collector is required for.
  • The characteristics of the dust particles that have to be separated.
  • Will the dust collector be used on a continuing basis or infrequently?
  • Will the dust collection unit be installed in an enclosed space or be placed in the open?

Consideration of the above-mentioned factors can greatly narrow down the search in your quest for the ideal dust collector for you.

The most appropriate dust collector for your requirements might be a unit that has –

  • The appropriate dimensions
  • A cleaning system that is well-equipped for the cleaning that you require.
  • A dependable ducting system
  • Proper filtration system that can effectively handle the size of the particulate matter

Always take your time to research the various options available and make an informed decision.

The dust collectors at a glance –

Type Main Uses Key Benefits
Inertial Separators Blasting operations, Plastics industry, Foundries, Food processing  Low cost  Low maintenance  Can handle high temperatures
Fabric Filters or Baghouses Plastics, Foundries, Food processing, Woodworking, Mineral processing  Versatile  Flexible  Can handle very small dust particle
Wet Scrubber To remove combustible metal dust aluminum, titanium, magnesium [the ‘iums’]  Neutralization of corrosive dusts and gases  Cooling down hot gases  Neutralization of corrosive dusts and gases  Cooling down hot gases  Explosive dusts are effectively handled
Electrostatic Precipitators [ESP] In the production of Electricity , used to remove soot and ash  Can handle a large volume of gas and large amounts of dust particles  Low maintenance  Low cost

Summary

There are several types of dust collectors and the choice of the right dust collector varies from industry to industry. While a baghouse might be perfect for removing fine dust generated in the woodworking industry, a cyclone dust collector might be more suited for dealing with coarser dust in the cement or rubber industry

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