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Electrostatistic Precipitation 155

Fig. 1. Steps for charging, transportation, neutralization, and removing of particles/ droplets
in the electrostatic fields.

process, the electrostatic forces are applied directly to the suspended particles in the
electrostatic fields (4). Current knowledge states that particles/droplets in the precipita-
tion process are charged, transported, neutralized, and removed as briefly described by the
following steps and illustrated in Fig. 1.
1. The particles/droplets are charged in passing through an ionized electrostatic field
2. The charged particles/droplets are transported by the electrostatic force onto the surfaces of
grounded collecting electrodes of opposite polarity
3. The charged particles/droplets are neutralized while arriving at the surfaces of collecting
electrodes
4. The collected particles/droplets are removed from the surfaces of collecting electrodes by
rappers, or other means, to a hopper beneath the electrostatic precipitator.
Electrostatic precipitators are built in either a single stage or two stages. Single-stage
precipitators are designed for the combination of discharge electrodes and collecting
electrodes together in a single section and are of two basic forms. The flat surface type
(also called plate–wire precipitator) consists of several grounded parallel plates that
serve as collecting electrodes, together with an array of parallel high-potential wires
mounted in a plane midway between each pair of plates; these wires are the corona dis-
charge electrodes (see Fig. 2A). The alternative single-stage precipitator design consists
of an array of grounded cylinders or tubes that serves as collecting electrodes; coaxial
to each cylinder is a high-potential wire, which is the corona discharge electrode (see