In order to study the incineration method of insulating oil contained small amount of PCBs (ND-50ppm), combustion test was conducted by using combustion facility which had flue gas treatment equipment's to keep safety supervision and environmental protection. Two type of operating condition was selected. The one was to assumed to actual boiler's condition including air heater and electrostatic precipitator. Another was assumed to the operating condition for the exclusive use of incineration of insulating oil contained PCBs. As a result, it was proved that the small amount of PCBs contained in insulating oil could be decomposed by the incineration method using spray combustion if high combustion temperature and long residence time should be kept in furnace. Moreover PCDDs was not detected at the exit of boiler flue and at the exit of afterburning furnace.
