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Pollution Control Services, Inc.
On Site Technical Service for Wet & Dry Electrostatic Precipitators, Scrubbers & Baghouses Our People, Our Experience, Your Success |
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Electrostatic precipitation is a commonly used method for removing fine particulates from airstreams. In an electrostatic precipitator, particles suspended in the airstream are given an electric charge as they enter the unit and are then removed by the influence of an electric field. The precipitation unit comprises baffles for distributing airflow, discharge and collection electrodes, a dust clean-out system, and collection hoppers. A high DC voltage (as much as 100,000 volts) is applied to the discharge electrodes to charge the particles, which then are attracted to oppositely charged collection electrodes, on which they become trapped.
Particles
that stick to the collection plates are removed periodically when the plates are
shaken, or "rapped." Rapping is a mechanical technique for separating the
trapped particles from the plates, which typically become covered with a 6-mm
(0.2-inch) layer of dust. Rappers are either of the impulse (single-blow) or
vibrating type. The dislodged particles are collected in a hopper at the bottom
of the unit and removed for disposal. An electrostatic precipitator can remove
particulates as small as 1
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m
(0.00004 inch) with an efficiency exceeding 99 percent. The effectiveness of
electrostatic precipitators in removing fly ash from the combustion gases of
fossil-fuel furnaces accounts for their high frequency of use at power
stations.In a typical unit the collection electrodes comprise a group of large
rectangular metal plates suspended vertically and parallel to each other inside
a boxlike structure. There are often hundreds of plates having a combined
surface area of tens of thousands of square metres. Rows of discharge electrode
wires hang between the collection plates. The wires are given a negative
electric charge, whereas the plates are grounded and thus become positively
charge