The report gives results of a research program to: (1) compare various electrode systems for charging fine high-resistivity dusts; (2) investigate techniques for charging the dusts in a high current density corona system; (3) perform a laboratory scale feasibility study of selected charging systems; and (4) design, fabricate, and test a 0.47 cu m/sec (1000 acfm) pilot-scale precharger for application to a two-stage system for electrostatic precipitation of high resistivity particulates. A literature review of previous attempts to control back corona caused by high resistivity dusts, and limited theoretical and experimental investigations: eliminated the impracticable and evaluated potentially useful approaches to the development of charging systems for high resistivity dust, and resulted in the derivation of a new three-electrode particle precharger, upon which further developments were based. The three-electrode concept, tested in a small laboratory device, charged high resistivity dusts to levels achievable only on low and moderate resistivity dusts in conventional systems. Charging results remained good for a pilot scale system designed, built, and tested at a gas volume flowrate of 0.47 cu m/sec. A rugged version of the pilot scale precharger was tested as a part of a two-stage system, where the collector was a modified pilot scale ESP. The new technique has economic potential.

"Southern Research Institute." "August 1979." Includes bibliographical references. "Contract no. 68-02-2193, program element no. EHE624."