PURPOSE: To prevent the degradation in the dust precipitation efficiency of dust precipitating electrodes in an electrostatic precipitator by detecting the reverse ionization phenomena generated in the dust precipitating electrodes from the waveforms of secondary voltages and decreasing the applied voltage thereby removing the electric charge accumulated in dust layers.
CONSTITUTION: When the electric resistance of dust exceeds 1×1011Ω.cm on accumulation of the dust on dust preciptating plates during the operation of an electrostatic precipitator, reverse ionization phenomena take place, and the dust precipitating performance is considerably degraded. In this time the instantaneous value of the secondary current observed by the condenser function of the dust precipitator is the value wherein photoelectric current is superposed on the true corona discharge current. The peak voltage of the waveforms of said secondary voltage and the instantaneous value of the voltage thereafter are detected and are compared with the boundary voltage of the reverse ionization determined as a function of the peak voltage. According to the difference in the compared values, the presence or absence of the generation of the reverse ionization phenomena is detected. When the reverse ionization phenomenon arises, the applied voltage of the dust precipitator is decreased to remove the electric charge accumulated in the dust; thereafter the voltage is applied again to prevent the degradation in the dust precipitating performance.
YAMAMOTO ICHIROU
KUJI MANABU
ISHII YUKINORI
