Experimental Study On Electrostatic Precipitation With Spraying Corona Discharges

Nowadays, the precipitators in common use are mechanical precipitator, filtration precipitator,wet precipitator, and electrical precipitator. There are merits and defects in all kinds ofprecipitators. These days electrical precipitators are employed most widely. The separating force(electrostatic force was main part) in electrical precipitators acted on dust particles directly. So ithas many merits: high precipitation efficiency and disposal capacity, small pressure loss, lowconsumption on energy and so on.This thesis based on a technology which combined wet precipitation technology andelectrostatic precipitation technology. A great deal of experimental data was gained in theexperiment. In this paper, the corona onset situation, the V-I characteristics, the precipitationefficiency of spraying corona discharges and dry corona discharges were researched andcompared with each other. At the same time, the new discharge characteristics andprecipitation principle of spraying corona discharges were analyzed and discussed.The discharge electrode was grounded in this experiment;electrostatic precipitation withspraying corona discharges was formed. When the plate electrodes were connected to positiveHV, negative corona discharge was produced under the discharge electrode induction effects,and electrostatic precipitation with spraying negative corona discharges was formed.Contrarily, when the plate electrodes were connected negative HV, electrostatic precipitationwith spraying positive corona discharges was formed. The experiments shown that the onsetvoltage value of dry negative corona discharge was 12.5 kv. and the value of sprayingnegative corona discharge was 7 kv.. The onset voltage of spraying corona discharge wasmuch lower than that of dry corona discharge. Under the conditions of the same high voltageand gas flow rate , precipitation efficiency of spraying negative corona discharges reached to28% higher than that of dry corona discharge (from 78.2% to 84.2%). The reason was thatelectrostatic agglomeration and dynamic agglomeration on dust from the charged dropletswere added in spraying negative corona discharge. The comparing between spraying negativeand spraying positive corona discharges showed that the precipitation efficiency of sprayingpositive corona discharge was lower than that of spraying negative corona discharge, becausethere was the phenomenon of corona plasma expanded in spraying positive corona discharge,and spraying negative corona discharge is more suitable for removal of particle contamination.The spreading corona plasma of spraying positive corona discharges plays an important rolefor purifying the spraying circulating water.