Method for removing an insulating fluid (PCB) from an electrical insulating part

Claim 1

The method for removing an insulating fluid containing polychlorinated biphenyl (PCB), which had been used as an insulating dielectric medium, from the pores of a porous solid electrical insulating part which had been immersed in the PCB-containing insulating fluid of an electrical apparatus from the group consisting of electrical transformers, chokes and capacitors, which comprises the steps of: (a) removing the insulating part from the electrical apparatus; (b) immersing the insulating part in a bath containing at least one fluid solvant for PCB selected from the group consisting of aliphatic, aromatic, chlorinated and fluorinated hydrocarbons; (c) moving the insulating part within the bath for a period of from 8 to 60 minutes at a speed of from 0.02 to 0.5 meters per second; (d) heating the solvent of the bath during said part immersion period from the ambient temperature to a final temperature of from 5° to 25° C. below the boilding temperature of the solvent at the pressure prevailing in the bath; (e) subjecting the solvent bath and the immersed insulating part to ultrasonic waves having a frequency of from 15 to 40 KKz. (f) measuring and monitoring the PCB-content of the solvent in the solvent bath and exchanging the solvent when a predetermined threshold value of PCB is exceeded; (g) said heating step comprising three operating stages-- (i) a first operating stage wherein said solvent bath is maintained at ambient temperature until the initial PCB threshold value of 5000 ppm of PCB is reached and "such" solvent is excanged for PCB-free solvent; (ii) a second operating stage wherein the solvent bath is heated to a temperature about midway between the ambient temperature and said final temperature and maintained thereat until a second PCB threshold value of 500 Ppm of PCB is reached and such solvent is exchanged for PCB-free solvent; and (iii) a third operating stage wherein the solvent bath is heated to said final temperature and maintained thereat until the predetermined threshold value of 30 ppm PCB is reached and then such solvent is exchanged for PCB-free solvent.

Claim 2

The method for removing an insulating fluid containing polychlorinated biphenyl (PCB), which had been used as an insulating dielectric medium, from the pores of a porous solid electrical insulating part which had been immersed in the PCB-containing insulating fluid of an electrical apparatus from the group consisting of electrical transformers, chokes and capacitors, which comprises the steps of: (a) removing the insulating part from the electrical apparatus; (b) immersing the insulating part in a bath containing at least one fluid solvant for PCB selected from the group consisting of aliphatic, aromatic, chlorinated and fluorinated hydrocarbons; (c) moving the insulating part within the bath for a period of from 8 to 60 minutes at a speed of from 0.02 to 0.5 meters per second; (d) heating the solvent of the bath during said part immersion period from the ambient temperature to a final temperature of from 5° to 25° C. below the boilding temperature of the solvent at the pressure prevailing in the bath; (e) subjecting the solvent bath and the immersed insulating part to ultrasonic waves having a frequency of from 15 to 40 KKz. (f) measuring and monitoring the PCB-content of the solvent in the solvent bath and exchanging the solvent when a predetermined threshold value of PCB is exceeded; (g) said heating step comprising three operating stages-- (i) a first operating stage wherein said solvent bath is maintained at ambient temperature until the initial PCB threshold value of 5000 ppm of PCB is reached and "such" solvent is excanged for PCB-free solvent; (ii) a second operating stage wherein the solvent bath is heated to a temperature about midway between the ambient temperature and said final temperature and maintained thereat until a second PCB threshold value of 500 Ppm of PCB is reached and such solvent is exchanged for PCB-free solvent; and (iii) a third operating stage wherein the solvent bath is heated to said final temperature and maintained thereat until the predetermined threshold value of 30 ppm PCB is reached and then such solvent is exchanged for PCB-free solvent.