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PARTICULATE CONTROL HIGHLIGHTS: RESEARCH ON ELECTROSTATIC PRECIPITATOR TECHNOLOGY
Citation:
Oglesby, Jr., S. AND G. Nichols. PARTICULATE CONTROL HIGHLIGHTS: RESEARCH ON ELECTROSTATIC PRECIPITATOR TECHNOLOGY. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/8-77/020a.
Description:
The report gives highlights of a major EPA research program on electrostatic precipitator (ESP) technology, directed toward improving the performance of ESPs in controlling industrial particulate emissions, notably fly ash from coal combustion in electric power plants. Relationships between electrical effects, such as reverse corona, caused by high resistivity of the deposited fly ash, have been investigated. The influence of fly ash particle size and chemical composition on the resistivity and dielectric strength of the deposited fly ash has also been studied. Relationships have been established between fly ash resistivity and chemical composition, especially its alkali metal content, for ESP operating temperatures below about 250C. Based on these relationships, a mechanism for ionic surface conduction has been proposed that complements the ionic mechanism in bulk conduction in fly ash particles at higher operating temperatures. The efficacy of conditioning fly ash by adding SO3 to flue gas (to lower fly ash resistivity) was established in trials at electric power plants. Reentrainment of particles from deposited fly ash has also been investigated in relation to ESP rapping procedures and gas flow distribution. A mathematical model of the ESP process has been developed, using fundamental relationships together with measurements of ESP geometry, electrical conditions, and particle size distribution.