CONTROLLING METHOD OF DUST COLLECTION ON ELECTRIC DUST PRECIPITATOR

PURPOSE:To collect dust and soot surely even if the operating conditions are changed in an electric dust precipitator by controlling the voltage impressed between the dust collecting electrode plates, when the oxygen concn. is sensed and the sensed value has become a reference value or less. CONSTITUTION:Since the dust and soot produced from a boiler 2 are closely related to oxygen concn., the oxygen concn. (observed value) C2 of the gas contg. dust and soot is measured with an oxygen densitometer 20. The C2 is supplied to an arithmetic circuit 22 to calculate the difference between the C2 and prescribed value C1 and the calculated result is supplied to an operation panel 24 for a dust precipitator 18 to control the operation controlling signal and also an electric source 26 of high voltage is controlled with the operation controlling signal and thereby the voltage impressed on the dust precipitator 18 is controlled. Thus, even if the operating conditions of the boiler are changed, the dust and soot discharged from a stack 14 are always suppressed to some constant value or less.