Removal of PCBs from electrical equipment by the vacuum heating separation method. I. Removal of low concentration PCBs from pole transformers

There are currently about four million pole transformers that were used for electric power supply throughout Japan that contain trace amounts (50mg-PCB/kg-insulation oil or less) of PCBs. The prompt creation of a safe disposal method to render this PCBs harmless is required. The authors performed tests on the removal of PCBs by a low temperature vacuum heating method, using pole transformers that had actually been placed in service and that contain low concentrations of PCBs. The results of these tests confirmed that under standard applicable conditions of a vacuum of 0.05 torr or less, a heating temperature of 200/spl deg/C and a vacuum holding period of 10 hours, the residual quantity of PCBs in impregnated transformer parts can be almost reduced to less than the quantitative determination lower limit of 0.05mg-PCB/kg-material. The test results also clearly showed that the test equipment and the disposal method do not have a harmful effect on the environment.