7. Principle of Electrostatic Precipitator:
Electrodes at high voltage create a corona effect
(ionized atmosphere) surrounding them. This
charges the passing particles. Once charged,
particles are subject to a transverse electrostatic
force that pulls them toward the collecting plates.
Plates are periodically “rapped” (vibrated) to make
the collected particles fall down into a receiver
basket in the bottom of the apparatus.
11. Construction of Electrostatic Precipitator:
It consists of thin wires called discharge or emitting electrodes and
other set called collecting electrodes in the form of pipes or plates.
The emitting electrodes are placed in the center of pipes or midway
between two plates and are connected usually to negative polarity of
high voltage source. The collecting electrodes are connected to
the positive of the source.
Steps in the process of precipitation:-
• Ionization of gases and charging of dust particles.
• Migration of the particle to the collector.
• Deposition of charged particles on the collecting surface
• Dislodging of particles from the collecting surface.
12. • Precipitator casing
• Hoppers
• Gas Distribution
System
• Collecting
Electrode System
• Emitting Electrode
System
• Rapping
• Reactifier
13. Working of Electrostatic Precipitator:
Dust particles are imparted an electric charge in a corona
discharge and then the charged particles are attracted in a strong
electrostatic field and precipitated onto the collector electrodes.
14.
15.
16.
17.
18. Types of Electrostatic Precipitator:
o Plate Wire Precipitator
o Tabular Precipitator
o Wet Precipitator
19. Plate Wire Precipitator:
In a plate wire precipitator, gas flows between parallel plates
of sheet metal and high voltage electrodes. These electrodes
are long wires weighted and hanging between the plates.
With each flow path, gas flows must pass each wire in
sequence as it flows through the unit. The plate wire
precipitator allow many flow lanes to operate in parallel and
each lane can be quite tall. As a result this type of
precipitator is well-suited for handling large.
20.
21.
22. Tabular Precipitator:
The original ESPs were tabular
like the smokestacks on which
they were placed with the high
voltage electrode running
along the axis of the tube.
23. The process gas vertically
enters the ESP from the
bottom by means of a Gas
Distribution System. The
particles are electrically
charged by the application
of high voltage, the
charged particles are
transported by
electrostatic attraction to
the Collecting Electrodes,
where they are
subsequently flushed off
periodically by a flushing
system.
Wet Precipitator:
24.
25. Applications of Electrostatic Precipitator:
Pollution control in Industrial Processes.( Chemical industries, Petroleum
industries, etc.
Static electricity is used in pollution control by applying a static charge to
dirt particles in the air and then collecting those charged particles on a plate
or collector of the opposite electrical charge.
Handles very large gas volumes and heavy dust loads with low pressure
drop.
In many industrial plants, particulate matter created in
the manufacturing process is released as dust in the hot exhaust gases. If
released into the atmosphere, the particulates reduce visibility, can contribute
to climate change, and lead to serious health problems in humans, including
lung damage and bronchitis. Fine particles that are smaller than 2.5 microns
(0.0001 inch) in diameter can be especially dangerous because they are
drawn deep into the lungs and can trigger inflammatory reactions.
Electrostatic precipitators are important tools in the process of cleaning up
flue gases.