Experimental Verification of Electrostatic Precipitator Stable Operation Under Oil and Co-fuel Firing Conditions of a Coal-fired Power Plant

Abstract

Electrostatic Precipitators are usually put into service after a complete shut-off of oil supply to the boiler burners of the furnace of a coal-fired power plant. However, such practice may lead to enormous dust concentration in the flue gas (design value is 37.9 g/Nm³ at 50%RO load) and heavy black smoke appearing at the stack outlet during the oil and/or co-fuel firing condition of boiler. To minimize such problem, an experimental study on charging and electrostatic precipitator operation during unit start-up and shut-down was carried out to verify de-dusting performance. It requires the manual control of the secondary voltages to be lower than sparking voltage of 10~15kV in case of oil and/or co-fuel firing condition of boiler. The study results prove that the electrostatic precipitator runs normally with good de-dusting performance (about 56.4 mg/Nm3 at unit start-up and within 31 mg/Nm3 at unit shut-down) and meets the Vietnamese environmental emission requirements as per proposed specified rules. From the study results, it can be predicted that Electrostatic Precipitators (ESP) & Sea-Flue Gas Desulphurization System (FGD) may be kept running during house load operation and run-back modes. Also, with the ESP and FGD running, the coal-fired power plant may not be limited to the loading dispatch at stable loads under co-firing condition below the minimum load of anthracite coal firing as required from power system.