Abstract: A multi-stage system is disclosed for removing particles from a gaseous medium and comprises an upstream precipitating stage of spaced corona discharging wires between parallel collecting plates, followed by a downstream precipitating stage having one or more electrically charges shells with flat sides generally parallel to collecting side plates for providing a uniform electric field in the medium carrying space, the sides of the shell having openings through which ions generated in the interior pass into the gaseous medium. A corona discharge apparatus inside the shell produces the ions at predictable, generally uniformly spaced locations. Alternative embodiments of the system include another stage located ahead of the upstream stage for removing the larger particles in the gaseous medium which can comprise a gravitational precipitator, a cyclone separator, a low voltage electrostatic precipitator or a low voltage ion beam generator.

Abstract: A multi-stage system is disclosed for removing particles from a gaseous medium and comprises an upstream precipitating stage of spaced corona discharging wires between parallel collecting plates, followed by a downstream precipitating stage having one or more electrically charged shells with flat sides generally parallel to collecting side plates for providing a uniform electric field in the medium carrying space, the sides of the shell having openings through which ions generated in the interior pass into the gaseous medium. A corona discharge apparatus inside the shell produces the ions at predictable, generally uniformly spaced locations. Alternative embodiments of the system include another stage located ahead of the upstream stage for removing the larger particles in the gaseous medium which can comprise a gravitational precipitator, a cyclone separator, a low voltage electrostatic precipitator or a low voltage ion beam generator.

Abstract: An improved collector structure is disclosed which is adapted for use in electrostatic precipitators to increase the efficiency of operation by increasing the electric field uniformity in the device and by reducing the power consumption without appreciably increasing reentrainment of the precipitated particles during operation. The collector is provided with an insulating material of the type which has an electrical relaxation time, .rho..epsilon., that is preferably greater than that associated with the particle current in the gas near the collector electrode, a triboelectric rank that is as low as possible if the collector electrode is negatively charged or as high as possible if the collector electrode is positively charged with respect to the opposite electrode and a thickness and resistivity such that the voltage drop across the insulation does not exceed about 5 to 10% of the applied voltage between the oppositely charged electrodes of the precipitator.