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174 Chung-Shin J. Yuan and Thomas T. Shen

Table 1
Ranges of Design Variables for Electrostatic Precipitators
Design variable Range of values
Migration velocity 3.1–21.4 cm/s (0.1–0.7ft/s)
2
2
3
Specific collection area (plate surface area/gas 19–95 m /(m /s) (100–500ft /
3
flow rate) – 1000ft /min)
Gas velocity 0.6–2.4 m/s (2–8 ft/s)
Aspect ratio (duct length/height) 0.5–2.0
3
Corona power ratio (corona power/gas flow) 100–1000 W/(m /s)
Applied voltage 30–75 kV
Electrical field strength 6–15 kV/cm (15–40 kV/in)
2
2
Corona current/plate area 50–700 µA/m (5–65 µA/ft )
Corona current/wire length 0.03–30.0 µA/m (0.01–10 µA/ft)
2
2
Plate area/electrical set 500–8000 m (5380–86,000 ft )
Space between plates 5–30 cm (2–12 in.)
Horizontal length of plate/vertical height of plate 0.5–1.0
Vertical height of plate 8–15 m (26–50 ft)
No. of high tension sections in gas flow direction 2–8
3
Degree of high-tension sectionalization 0.01–0.10 high-tension bus section/(m /s)
Source: Data from refs. 12, 13, and 19.

equation applies only to a very narrow particle size range and relatively constant
migration velocity.
Example 4

Find the collecting plate area of a horizontal-flow, single-stage electrostatic precipitator
3
handling an average gas flow of 2.5 m /s from a pulverized coal-fired boiler. The required
collection efficiency of ESP is 98%.
Solution
3
Given: η = 98% and Q = 2.5 m /s
From the data given in Table 2, select w = 12 cm/s (or 0.12 m/s).
− (
1
η= − exp wA Q )
098 = 1 − exp − ( 012A / 25)
.
.
.
)
A = (1 − 0.98 )(2.5 / 0.12
ln
2
= 81.5 m (required)
Reference is made to the ranges of design variables shown in Table 1. The width of the
plates is generally between 0.5 and 1.0 times the height. Therefore, use two sections
formed by plates of 4.0 m wide × 5.2 m high on 25-cm centers.
Total collecting plate area = 2 × 4.0 × 5.2 × 2 = 83.2 m ( provided)
2