Process for the extraction of oil or polychlorinated biphenyl from electrical parts through the use of solvents and for distillation of the solvents

A combined process for the extraction of oil or polychlorinated biphenyl from parts having electrical insulation impregnated with a dielectric liquid containing oil or polychlorinated biphenyl, by means of a highly volatile solvent, and for the distillation of the solvent from a mixture of oil or polychlorinated biphenyl with the solvent, comprising the steps of:

• locating parts to be cleaned in an evacuated autoclave;
• introducing a highly volatile solvent into said autoclave;
• evaporating the highly volatile solvent during a heating phase in at least one evaporator located in the autoclave;
• condensing the solvent on said parts thereby heating said parts so that said solvent penetrates into the electrical insulation of the parts and so that the condensation heat of the solvent dissolves the oil or the polychlorinated biphenyl out from said electrical insulation;
• and
• effecting a plurality of intermediate pressure reductions during the heating phase such that during each intermediate pressure reduction, the supply of the solvent is discontinued and the mixture is circulated in order to simultaneously carry out a distillation phase so that the highly volatile solvent is distilled out of the oil or polychlorinated biphenyl-solvent mixture directly from the autoclave, wherein the pressure after each intermediate pressure reduction is reduced to between 1 to 100 mbar.