Electrostatic precipitator percent collection efficiency

The fraction of particles collected is sometimes reported in terms of percent collection efficiency (after multiplication by 100). Values of such efliciencies in a few operating plants are indicated in Figure 7.3.9, which identifies only a few major types of installations. The use of electrostatic precipitators is widespread additional examples of where they are used are cement plants, in the steel industry, in smelting operations, in the chemical industry, the petroleum industry, in carbon black factories, foundries, etc. In such industrial applications, industrial practice suggests techniques other than electrostatic precipitation for particles in the range 0.1-1 pm since the value of is <0.99 and decreases with a decrease in Vp (Donovan, 1985 Eggerstedt et al., 1993). 

FIG. 17-69 Design curves for electrostatic precipitators for fly ash. Collection efficiency for various levels of percent sulfur in coal versus a) specific collecting surface, and (h) bus sections per 100,000 ftVmin (4.7 mVs). °C = (°F — 32) X (Ramsdell, Design Criteria for Precipitators for Modern Central Station Power Plants, Amen c m Power Conference, Chicago, III., 1968. )... 

Thus an M X N electrostatic precipitator consists of M cliambers and N fields. A precipitator is "out of compliance" when its overall collection efficiency falls below a designated minimum because of bus section failures. Wlien several bus sections fail, tlie effect of the failures depends on where tliey are located. To detemiine directly whetlier a precipitator is out of compliance after a given nmnber of bus sections liave failed, it would be nec ssaiy to test all possible arrangements of tlie failure locations. The out of compliance probability is given by tlie percent of arrangements tliat result in overall collection efficiencies less tlian tlie prescribed minimmn standard. The nmnber of arrangements to be tested often makes tlie direct approach impractical. For example, Theodore et... 

Electrostatic Precipitators. Electrostatic precipitators (ESPs) are extremely efficient air pollution control devices that can remove more than 99 percent of the particles in a gas stream (Fig. 4.66). This high efficiency is possible because, unlike other pollution control devices, the precipitator applies the collecting force only to the particles to be collected, not to the entire gas stream. Thus, an extremely low, energy-saving power input [about 200 W per 1000 ft /min (0.5 mVs)] is required. 

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