Page 2 - LN-CH-16

• About 99% of particulate matter can be removed by ESP.
• It has electrode wires and a stage of collecting plates.
• Electrode wires are provided with an electric current of several thousand volts, which
produces a corona that releases electrons.
Discharged corona Negatively charged wire
• These electrons get attach to the dust Electrostatic precipitator
particles and give them negative
charge within a small fraction of a second.
• Collecting plates are grounded that attract the charged dust particles.
• The velocity of air between the plates must be low enough to allow the dust to fall.
(b) Scrubber is used to remove harmful gases like sulphur dioxide from industrial
exhaust.

The exhaust is passed through a spray of water or lime.
• Water dissolves the gases and lime reacts with sulphur dioxide to form a precipitate of
calcium sulphate and sulphide.
* Drawbacks Recently, the dangers of particulate matter that are very small and cannot be
removed by these precipitators has been found. According to Central Pollution Control
Board (CPCB), particulate size 2.5 micrometers or less in diameter (PM 2.5) if inhaled can
cause breathing and respiratory problems, irritation, damage to lungs and premature deaths.