Particle motion is a blessing in disguise. Please illustrate the statement with at least 5 points with examples in relation to relief from air pollution hazard. Best answer will be marked as brainliest. 50 points.
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Particle removal—cyclone
A cyclone works on the principle of creating a high-speed spiral airflow to remove particles. This spiral motion applies a centrifugal force on the particles.
The inertia of the particles forces them to the outside walls of the cyclone, where they fall to the bottom and are collected.
The speed of the airflow and the width of the cyclone influence particle removal—the smaller the diameter the more efficient the particle removal.
The conical section at the base of the cyclone gradually decreases the diameter of the spinning gas stream, resulting in better removal of smaller particles.
However, in practice, reducing the diameter increases the pressure drop across the cyclone. Combining several units together as a ‘multicyclone’ can prevent this.
Electrostatic precipitator
Particle removal—electrostatic precipitator
The electrostatic precipitator works by removing particles and smoke from a gas stream using an electrostatic charge.
Dust particles travel past wires that have a high direct current (DC) voltage applied, which ionises the surrounding gas. This corona discharge causes the particles to pick up a small electrostatic charge.
An oppositely-charged plate attracts the particles, neutralises and retains them. A regular tapping (rapping) of the plates then physically removes the collected particles.
Introducing a water spray can reduce the electrical resistance of the dust particles, allowing them to accept the charge more easily.
Electrostatic precipitators are an efficient way of removing particles and do not cause a significant pressure drop across the unit.
Particle removal—bag filters
Bag filters use fabric bags to remove particles from dust-laden gas.
They can achieve high efficiencies for fine particles because of the build-up of particles on either the inside or outside surface of the bag depending on the design.
As dust builds up, the pressure across the bag increases, so the filters need regular cleaning. Usually bag filters work in tandem—one filter is working while the other filter is being cleaned.