Dust collection current flow

When corona occurs, current starts to flow in the secondary circuit and some dust particles are precipitated. As potential is increased, current flow and electric field strength increase until, with increasing potential, a spark jumps the gap between the discharge wire and the collecting surface. If this "sparkover" is permitted to occur excessively, destmction of the precipitator s internal parts can result. Precipitator efficiency increases with increase in potential and current flow the maximum efficiency is achieved at a potential just short of heavy sparking. 

A second effect of high fly ash resistivity is observed when the difference in potential across the collected dust layer rises to too high a value. A back corona can form as the EMF differential breaks down due to sparking across the dust layer. High currents flow between the wire cathode and plate anode thereby destroying the ability of the ESP to charge particulates. 

The amount of particulate collected on the filter is determined by weighing the filter under the same physical conditions as prior to sampling. The amount of particulate with respect to total sampling time and flow rate determines the dust concentration in milligrams per cubic meter (mg/M ). The current OSHA Threshold Limit Value for nuisance or inert respirable dust is 5 mg/M. ... 

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