FR2591383A1 - METHOD AND APPARATUS FOR REMOVING POLYCHLORINE DIPHENYL FROM AN ELECTRICAL APPARATUS - Google Patents

Abstract

The invention relates to a method and a device for removing polychlorinated biphenyls from electrical devices, in particular transformers, so as to achieve concentration levels of 50 ppm or less. A dielectric fluid is chosen having a relatively low boiling point compared to polychlorinated biphenyls and other contaminants; an external cooling loop is provided in which the dielectric fluid is passed while maintaining the temperature and the pressure of the transformer within these design limits; an external distillation loop is provided where the liquid removed from the transformer is heated to the boiling point of the selected dielectric fluid in order to vaporize the dielectric fluid and remove the polychlorinated biphenyls in liquid phase in the distillation vessel; the dielectric fluid vapor is then condensed and returned to the transformer to dissolve any PCBs remaining therein. (CF DRAWING IN BOPI)

Description

METHOD AND APPARATUS FOR REMOVING DIPHENYL POLYCHLORINE

AN ELECTRICAL DEVICE

  The present invention relates generally to electrical inductive apparatus, such as transformers, and more particularly to the removal of residual polychlorinated biphenyl from

  internal components of electrical inductive devices.

  Since about 1930, electrical transformers used in places that could be affected by fire or fire damage, such as underground, buildings and factories, have been made with biphenyl-based insulation and cooling fluids. polychlorinated, these liquids being commonly referred to as PCBs. PCBs have been chosen for these applications because of their great

  dielectric strength and good fire resistance.

  In 1976, the manufacture of PCBs was legislated in the United States of America (15 U.S.C.A. 2605 (3) (A) (i)) because of its carcinogenic nature. The Federal Toxic Substances

  Control Act "made it mandatory that the use of PCB in the indus-

  is gradually reduced to zero in a short period of time.

  The Environmental Protection Agency determined that PCB concentrations of 50 ppm or less in the dielectric fluid of a transformer were considered safe for transformer operation. The EPA further stipulated that a PCB-containing transformer may be reclassified as "non-PCB-free" if, 90 days after completion of decontamination (and emptying), the concentration

  residual PCB in the dielectric fluid is less than 50 ppm.

  Because initial concentrations of PCBs in these transfor-

  can reach values as high as 600 000 to 1 000 000 ppm and since PCB impregnates the cellulosic insulation material (wood and paper) and other absorbent insulating materials used in transformers, a simple

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  Rinsing the transformer with another dielectric fluid or solvent may have the effect of immediately reducing the PCB concentration to an acceptable level, but after a certain period of operation, the concentration rises again above the set limit. by the EPA, because concentrated PCB is removed from

  continuous way of solid insulation by leaching.

  In the prior art, there is reported a method for removing PCB from transformers by using an activated carbon filter which is placed in a thermal siphon attached to the transformer while it is energized (US Patent Specification). America 4,124,834). The

  Activated carbon filters have a limited capacity for PCB absorption.

  It is, therefore, necessary to continually change the activated carbon filters and to control the PCB concentrations. The process is continued until the PCB concentration in the dielectric fluid falls below 50 ppm. Although the fluid can reach a PCB concentration of 50 ppm, approximately 30 to 60 days, when it is discharged from the transformer, this fluid, which is a bad solvent for the PCB, rapidly returns to leaching at a concentration well above 50 ppm. To date, this process has been applied continuously to transformers for two (2) to three (3) years without the PCB concentration being maintained.

  satisfactory way below 50 ppm after emptying.

  Also known in the prior art is a process which seems to provide for circulating a chlorinated or halogenated aliphatic hydrocarbon vapor through the transformer (US Patent 4,425,949). The equipment necessary for the implementation of

  this process comprises two pumps, a decanter, a device for

  thermo-siphon boil, two inert chillers, a condenser, an overheating exchanger, a tank and an optional distillation vessel. The obligation to provide this quantity and complexity of equipment is apparently imposed by the fact that the cleaning of the transformer is carried out in the vapor phase and not in the liquid phase. This

  degree of complexity would obviously result in large investment costs.

  high operating expenses and high maintenance costs. In addition, the process described in the US patent

  of America 4,425,959 is to be implemented while the transformation

  It is out of order because existing PCB transformers are not designed to operate in a dielectric gaseous atmosphere and the resulting absence of heat dissipation would cause the transformer to fail or burn. Failure to operate the transformer during decontamination prevents heating and subsequent expansion of the windings and the transformer core. The disconnected condition prevents, in the steam cleaning process of US Patent 4,425,949, access to PCB internally trapped and which remains thereafter until the

  transformer is refilled and reconnected.

  It is an object of the present invention to provide an advantageous method and apparatus for removing PCB from a transformer and for maintaining therein a satisfactory low level of concentration.

of PCBs.

  It is also an object of the present invention to provide an advantageous apparatus and method which is cost effective in terms of cost and

  time and which effectively remove PCBs from a transformer

  in such a way that the introduction of residual PCBs by leaching

  in the dielectric fluid does not exceed 50 ppm.

  The present invention also provides an advantageous method and apparatus for removing PCBs from a transformer and

  do not require constant control.

  The present invention also provides an economical method and apparatus for removing PCBs from a transformer, which do not require

  a moderate expenditure on equipment.

  The present invention creates an advantageous method and apparatus that can be implemented on a transformer in service without substantially affecting the efficiency or power consumption thereof. The present invention also relates to a method and an apparatus

  which can be used on an off-grid transformer.

vice.

  Still another object of the present invention is to provide a method and apparatus for removing PCBs, the apparatus being readily reinstallable on an existing transformer which is filled with PCBs

or contaminated by it.

  One of the advantages of the present invention is that the transformer can be returned to service quickly and the decontamination process can be continued without further interruption of the electrical service. Another object of the present invention is the creation of a method, as well as an apparatus which is sufficiently compact and of a weight sufficiently light to allow access to the cavities of a transformer filled with PCBs, these cavities are often indicated by the fact that they constitute remote and difficult areas.

to reach.

  These features and advantages of the present invention, as well as many others, will be highlighted by the careful reading of

  the following detailed description, as well as the claims and

  drawings, a description of a process and apparatus for

  remove, collect and isolate PCBs. This goal is achieved by using trichlorotrifluoroethane both as a dielectric fluid and as

  solvent and connecting two fluid circuits to a transformer.

  Other fluids with similar characteristics of dielectric strength and flammability, as well as boiling point well below the boiling point of PCBs and in which PCBs are

  soluble, could also be used in the process. The per-

  Chlorethylene constitutes such a material.

  Other suitable dielectric fluids / solvents may include

  perfluorocyclic ether (C6F120), perfluorobicyclo (2,2,1) -

  heptane, perfluorotriethylamine, monochloropentadecafluorheptane, perfluorodibutyl ether and perfluoro-n-heptane, although these dielectrics were not tested to determine: (1) whether the PCBs are soluble therein; (2) if they are compatible, without destructive effect, with the internal parts of the transformer; (3) if they form an azeotrope with PCBs. If PCBs are not soluble in one of the dielectrics mentioned above, or if a particular dielectric damages the transformer, or if a particular dielectric forms an azeotrope with

  PCB, this dielectric is not suitable then.

  The second of these fluidic circuits contains a condenser or other cooling means through which the dielectric fluid vapor produced by the heat of the transformer passes and through which the resulting condensate is returned to the transformer thereby removing latent heat and controlling the atmospheric pressure prevailing inside the transformer while maintaining the temperature of the dielectric fluid approximately at its boiling point in the transformer. The first fluid circuit contains a distillation means in which the temperature of the dielectric fluid is increased to the boiling point of the solvent consisting of trichlorotrifluoroethane. The excess heat generated by the transformer is advantageously exploited to reduce the energy

  necessary for the distillation of the solvent. The resulting vapor pro-

  in the first fluid circuit is taken at the head of the distillation means to be fed to a condenser via a conduit. The condensate is transmitted by gravity through a conduit to a tank and is pumped back to the transformer from the tank. Because the temperature inside the medium

  distillate is maintained at the boiling point of the trichlorotril-

  fluoride, PCBs, which have a much higher boiling point,

  remain in the liquid phase and are collected at the bottom of the distillate

lation.

  Periodically, PCBs are drained from the bottom of the distillery

  to a PCB waste tank.

  Application of the process of the present invention while the transformer is in operation is the most efficient method of practicing the invention. The porous internal parts of a transformer expand due to the increase in temperature

  occurs when the transformer is in operation. This dilation

  It exposes a larger surface area of the porous internal parts to the dielectric fluid and allows saturated PCBs in

  porous internal parts to be removed by leaching.

  Since the leaching or diffusion rate of PCB has

  from the transformer core is greatly affected by the temperature

  and the concentration gradient (concentration difference between the PCB in the core and the PCB in the dielectric), it is important to reduce the PCB concentration in the dielectric to a very low value (less than 2). ppm) as quickly as possible. The invention ensures that this occurs in the period between the first (1) and the fifth (5) day depending on the volume of the transformer, and then a continuous evacuation (via a distillation) of the residual PCB that is leached into the low-temperature dielectric

  PCB concentration. An additional advantage of the method

  both to operate the transformer being decontaminated lies in the fact that the fluctuations of the electrical current passing

  in the transformer generate an action of swelling and contraction

  (pumping) which accelerates the evacuation of the PCB from its

  internal insulation and materials.

  Since the first fluidic circuit starts from the bottom of the transforma-

  Other soluble contaminants as well as contaminants of a heavy and particulate nature are also likely to be discharged from the transformer by the distillation process of the first fluid circuit. Such undesirable contaminants may include

  dust, water, mud, trichlorobenzene and tetrachloro-

  benzene. Other features highlighted in the following and benefits of the invention will be put

  description, given as an example

  FIG. 1 is a block diagram showing the invention to a transformer in FIG. 2 is a block diagram showing the invention and a transformer showing another mode.

cooling medium.

  Now considering the drawings, we see represents an existing transformer to which were: the application of existing PCB; the application of existing PCBs and the realization that FIG. 1 adds two fluidic circuits which, when operating, serve to cool and

to clean the transformer.

  For a short time, the transformer is taken out of service.

  During this period of rest, the PCBs are evacuated from the transformer and the transformer is rinsed with a solvent to remove most of the PCB residues and the dielectric. This solvent should be,

  without being limiting, the dielectric fluid which is later

  used to decontaminate the transformer. The transformer is then refilled (with trichlorotrifluoroethane as a dielectric fluid) and a partial vacuum is established in the transformer to evacuate air and / or moisture that may have been introduced.

  during the rinsing and filling stages.

  A quick disconnect coupling 3 is coupled with the existing discharge or drain port on the transformer. The fluid

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  dielectric flows through this quick disconnect fitting 3 to enter a conduit 20. The connector 3 is the starting point of a first fluid circuit. This first fluid circuit first discharges dielectric fluid from the transformer and ends up returning dielectric fluid to the transformer. The first fluid circuit operates to clean the PCB transformer. The cleaning is carried out by circulating the dielectric fluid in the liquid phase through the transformer. The

  PCBs contained in the transformer are soluble in the dielectric fluid

  and, consequently, when the dielectric fluid leaves the trans-

  As a trainer flowing in the first fluid circuit, the dielectric fluid is charged with PCB in solution. The solution is then distilled. In the distillation operation, the dielectric fluid is vaporized while the PCBs remain in the liquid phase. This is because the dielectric fluid has a boiling point well below the boiling point of the PCBs. The boiling point of the dielectric fluid must be lower than the boiling point of the PCBs. The dielectric fluid vapor is then condensed and returned to the

  transformer where it can then dissolve PCB again.

  During the first hours of application of the process, the concentration

  The amount of PCB in the dielectric fluid increases considerably (20,000-60,000 ppm). This is because the initial rinsing of the transformer with trichlorotrifluoroethane does not reach the

  very little exposed areas of the porous internal parts of the transformer.

  As a result, when the transformer warms up during operation,

  residual PCBs saturated or trapped in the porous inner parts begin to dissolve in the dielectric fluid,

  namely trichlorotrifluoroethane.

  In the first fluid circuit, from the disconnector A

  3, the dielectric fluid is transmitted through the

  20 to a solenoid valve 21 which controls the flow of the dielectric fluid to the distillation means 23. Inside the distillation means 23, a high level detector 25 and a low level detector are provided. 27. The high level detector 25 excites a high level controller 29 while the low level detector 27 excites a low level controller 31. The high level controller 29 and the low level controller 31 actuate the solenoid valve 21 of the way to maintain a proper level of liquid inside the means of

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  distillation 23. The thermal energy needed to reach the point

  boiling of the dielectric fluid inside the distillation means

  23 is provided by a coil and electric resistance heater 33. A heat recovery heat exchanger, which draws its energy from the heat escaping from the condenser 37, can replace the electric resistance heater. A correct level is a level allowing the formation of a volume of steam at the top of the distillation means 23 while maintaining a liquid level such that the electric resistance heater 33 is completely immersed. When the dielectric fluid begins to boil, the resulting vapor is sent to a condenser 37 through a conduit 35. Condensed dielectric fluid from the condenser 37 is channeled through a conduit 38 to a steam separator 40 from

  separating water that may have been evacuated from the

  with the dielectric fluid. The water thus separated from the dielectric fluid

  is sent to the distillation means 23 via a

  42. The remaining dielectric fluid is collected in a tank.

  see condensate 39 through a conduit 46. There is provided near the bottom of the condensate tank 39 a suction pipe 41 which leads to a pump 43. It is provided inside the condensate tank 39 a high level detector 45 and a low level detector 47. The high level detector 45 excites a high level controller 49 while the low level detector 47 excites a low level controller 51. The high level controller 49 and the low level controller 51 operates the pump 43 to maintain a proper level within the condensate tank 39. A correct level is a level for which the pump 43 does not perform vacuum pumping and for which no overflow occurs in the tank 33. The pump 43 discharges the fluid via a shut-off valve 44 and a return pipe 53 to return it to the transformer via

  through the existing filling port on the transformer

  tor. The stop valve 44 is connected to the solenoid valve 21 and allows the distillation part of the system to operate at atmospheric pressure, or at a pressure different from and lower than

  which the transformer operates. This allows distilling

  The dielectric has a lower boiling point (due to the

  lower pressure); in addition the energy consumption for ebulli-

  tion is smaller and a good separation is achieved between the dielectric and the contaminant. There is provided a filling pipe 54 which opens into the condensate tank 39 and through which trichlorotrifluoroethane can be added to replace the volume of PCB and trichlorotrifluoroethane removed. The condensate reservoir 39 provides certain special advantages in the

  process. Although we can simply omit the condenser tank

  By placing the condenser 37 at a certain level above the transformer and discharging the fluid from the condenser 37 directly to the transformer, an explanation of these advantages will make it clearer to understand why the condensate reservoir 37 is part of the preferred embodiment. Firstly, the condensate reservoir 37 makes it possible initially to introduce into the system an excess of dielectric fluid / solvent so that it is not necessary to add a complement of dielectric fluid / solvent to replace that which leaves the system. when the substances recovered at the bottom are discharged to the PCB waste tank 69. In addition, it is possible to

  dielectric fluid / pure solvent during the continuous execution of the

  while simultaneously being able to evacuate larger quantities of

  PCB-contaminated dielectric fluid / solvent to the dif-

  23. This speeds up the entire process by greatly increasing the dilution rate of PCBs inside the transformer.

  by the dielectric fluid / solvent. In addition, the deletion of

  see condensate 39 and pump 43 would require the omission of the stop valve 44 and the resulting benefits derived as indicated

  previously of the use of a stop valve 44 would also be

lost.

  At the bottom of the distillation means 23, there is provided a conduit 58 through which tail products are fed to a manually actuated gate valve 76 which is normally closed, or to a solenoid valve 61. The solenoid valve 61 is actuated by a controller 67 which receives a signal from the temperature sensor 65 placed in the vapor space of the distillation means 23 When the concentration of PCB and other high-boiling contaminating substances in the distillation means 23 increases, the boiling point of the solution of trichlorotrifluoroethane and PCB

  It also increases, which in turn causes a rise in temperature.

  in the vapor space of the distillation means 23.

  When the temperature sensor 65 detects a temperature of about 74 ° C., the controller 67 opens the solenoid valve 61 and the fluids

  in the PCB 69 waste tank through the

  The temperature at which the controller 67 is set to actuate the solenoid valve 61 can be modified in a

  broad range, although it should be remembered that separation by distillation

  tion is improved when the boiling point of the solution becomes

  approaches the boiling point of the dielectric fluid. It is obviously necessary

  Select a setting at a temperature other than 74 C when a dielectric fluid other than trichlorotrifluoroethane is used in the process. When this occurs, a low level of liquid is detected by the low level detector 27 and the bottom controller

  level 31 makes the solenoid valve 21 open to

  and adding an additional amount of electric fluid to the distillation means 23 and flushing the tail fluids which are highly concentrated to PCBs for delivery to the PCB waste tank 69. At the end of a period preset by means of the timer 73, and sufficient for the evacuation and rinsing of

  tail fluids, the solenoid valve 61 is closed and the distilling means

  23 resumes normal operation. After rinsing the PCBs already removed from the transformer and sent to the PCB waste tank 69, the dielectric fluid contained in the distillation means 23 has a much lower content of PCB contaminants. This means that the boiling point of the solution again approaches the boiling point of pure trichlorotrifluoroethane and, as a result, the separation by distillation reaches its optimum. The PCB 69 waste tank may be of a conservable or disposable type; however it is preferable that it be disposable. By making the disposable PCB 69 waste container, it is

  possible to easily remove it and replace it with another

  see at any time during the process, thus removing PCB contaminants from the facility. This possibility reduces the risk of disturbances in the event of fire or flood

  most of the PCBs will have already been removed from the facility.

  Manually operated gate valve 76 can drain

  the distillation means 23 at any time during operation.

  at the end of an operation, through the intermediary of

leads 77.

  It is provided a gate valve 75 manually operable and

  by means of which the PCB 69 waste tank can be emptied.

  A second fluid circuit operates to cool the dielectric fluid as it passes therethrough, thereby dissipating the heat generated by the transformer. The second fluid circuit also serves to maintain the pressure inside the transformer within the limits corresponding to the normal operation of the transformer. It should be noted that existing PCB transformers have been constructed to operate at low pressure (0.35 to 0.5 x 105 Pa) and must have suitable means for controlling the vapor pressure to operate in a manner safe. The temperature and pressure are controlled by means of a condenser 15. Part of the fluid

  dielectric is vaporized by the heat generated by the

  transformer. This dielectric fluid vapor is sent to the condenser 15 by convection by means of a conduit 17. A forced draft system for transmitting steam via the second fluid circuit could also be used when a faster cooling is imposed. or when unevenness prevents the

  natural rise required for convection cooling.

  The dielectric fluid condensed by the condenser 15 is returned

  by gravity in the form of a liquid phase to the transformer through the

  19. This method of evacuation of the latent heat of the

  dielectric fluid is an extremely efficient way to cool

  dir transformer, while simultaneously limiting the pressure of

  steam inside the transformer.

  There is provided an emergency pressure relief valve 85 operating in an emergency and which is connected to the condenser 15 via a conduit 84. When a power failure occurs, the second fluid circuit can not cool the fluid dielectric and residual heat remaining in the transformer is not dissipated. This results in a pressure increase in the condenser 15. In such a situation, the discharge or safety valve 85 opens to lower the pressure inside the condenser. The vapor escaping from the condenser 15 is channeled through the conduit 84, the safety valve 85, the conduit 86, the vapor absorption carbon column 82 and the conduit 83. The vapor absorption column 82 absorbs the dielectric fluid vapor / solvent thereby preventing dielectric fluid vapor, which could have an asphyxiating effect, from entering a closed area where the transformer can be placed. Furthermore, although it is extremely unlikely that the temperature reached in such a situation would be sufficient to cause PCB vaporization, the vapor absorption column 82 absorbs any PCBs that can

  flow with the dielectric vapor through the safety valve

85.

  Another method of cooling the transformer is

  2. In this example, the second fluid circuit provides cooling of the dielectric fluid by use of a heat exchanger 16 cooled by air or mechanically. Dielectric fluid is transmitted to the pump 9 via the quick connect fitting 3, the T-piece 5 and the conduit 7. A sensor

  temperature 11 is provided in the conduit 20. The temperature sensor

  11 excites a temperature controller 13 which actuates the pump 9.

  The pump 9 discharges the dielectric fluid through a cooled heat exchanger 15. The dielectric fluid is then circulated in the conduit 18 and returned to the transformer. The dielectric fluid is discharged through the second fluid circuit by the pump 9 which is controlled by the temperature controller 13

  to maintain the temperature of the dielectric fluid in the trans-

  trainer close but below his boiling point.

  This other method of cooling is particularly useful when there is a boiling condition on the surface of the transformer windings where bubbles occur in the interface between the liquid and the solid. It is possible for such a bubble to extend from one winding to another, thereby displacing the dielectric fluid. When this occurs, there is a risk that, in the case of high voltage operation, an arc burst will occur.

  disruptive between the windings. This other method of cooling

  may be used to prevent boiling with bubble formation by maintaining the temperature of the dielectric fluid below

of its boiling point.

  In another embodiment, the condenser 15 and the condenser 37 shown in FIG. 1 are replaced by a single condenser fulfilling a dual function, namely the maintenance of the temperature and the pressure inside the transformer and the condensation distilled dielectric fluid vapor for return to the transformer. In addition, the provision of such a dual-function condenser at a location above the transformer would eliminate the need for pumping. Steam would rise by convection at a time

  from the transformer and the distillation means 23 to the condensate

  dual-function and the resulting dielectric fluid, in the liquid phase, would flow by gravity from the dual-function condenser

to the transformer.

  It should also be noted that when perchlorethylene is used

  as a dielectric fluid / solvent in a transformer

  vice, it may not be necessary to use an outer cooling loop. This is because the boiling point of perchlorethylene is substantially higher than the boiling point of trichlorotrifluoroethane and, depending on the type of transformer, the heat

  caused by the operation of the latter may not be sufficient

  to boil perchlorethylene. The disadvantage of using perchlorethylene is that PCBs are more

  difficult to separate from perchlorethylene because it has a boiling point

  significantly higher, and a latent heat of vaporization

  greater than trichlorotrifluoroethane.

  In summary, a method for removing PCBs from trans-

  trainers which is based on a distillation and which, except for a brief initial shutdown period, may, but need not necessarily be

  while the transformer is running. This is important

  both because many existing PCB transformers are

  in places that make it difficult, if not impossible, to replace

  or at least make it difficult to decommission the

  transformer for an extended period.

  Additionally, the process is energetically extremely

  effective because it uses the heat generated by the transformation

  in use to accelerate the extraction of PCBs. In addition,

  that the dielectric fluid is kept at an approximate temperature

  equal to its boiling point, the additional amount of

  heat required for distillation is reduced to a minimum.

  If one wishes to implement the invention while the transformation

  If the meter is not in use, it may not be necessary to install or use the second fluid circuit because the transformer

14 2591383

  itself would not add heat to the

  dielectric fluid / solvent and that a vaporization of the dielectric fluid

  The tip / solvent inside the transformer would not occur. In other words, a cooling of the dielectric fluid / solvent in the transformer would not be necessary because, in this situation, the dielectric fluid / solvant would not serve to dissipate the

  heat generated by an active transformer.

  However, an implementation of the invention in this way would not be as effective as an implementation of the invention while

  the transformer is active. When the transformer is in operation

  The resultant heat results in an expansion of the internal parts of the transformer, particularly wrapped windings of cellulosic material, thereby permitting faster and more efficient penetration.

  complete dielectric fluid / solvent.

  It should be noted that the invention can be put into practice on a transformer not in service at an increased speed if a source of

  heat is used to heat the dielectric / sol-

  from the transformer core. In either case, the added heat causes the internal parts of the transformer to expand in a manner analogous to what has been described for a transformer operating. However, in such a case, care should be taken not to

  overcompress the transformer because the added heat causes

  would be significant vaporization of the dielectric fluid / solvent. If the

  dielectric fluid / solvent temperature reaches its boiling point

  it is necessary to use external cooling means.

  It is contemplated that once the transformer has been cleaned of PCBs, the dielectric fluid / solvent is drained from the transformer and replaced with another suitable dielectric fluid such as silicone oil. However, it would also be possible to remove the transformer cleaning circuit while leaving the cooling circuit in place. This would allow the processor to

  function permanently using trichlorotrifluoride

thane as a dielectric fluid.

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Claims (17)

  1. A process for removing polychlorinated biphenyls from an electrical apparatus in operation or at rest, characterized in that it consists in: a) introducing into the electrical apparatus a dielectric fluid, in which PCBs and other contaminants are soluble such that the polychlorinated biphenyls contained in the electrical apparatus form a solution with said dielectric fluid; b) channeling said solution of the electrical apparatus to a cleaning means in its path, such that said dielectric fluid can be separated from the polychlorinated biphenyls and other contaminants;   c) purifying said solution to thereby separate polycyclic biphenyls   res and other contaminants of said dielectric fluid such that said dielectric fluid can be reused in substantially pure form; d) recycling said dielectric fluid to the electrical apparatus for its reuse.   2. A process for removing polychlorinated biphenyls and other contaminants from transformers in operation and at rest, or other electrical apparatus, characterized in that it consists in: a) introducing into the electrical apparatus a dielectric fluid wherein polychlorinated biphenyls and other contaminants are soluble so that the polychlorinated biphenyls contained in the electrical apparatus form a solution with said dielectric fluid; b) channeling said solution of the electrical apparatus to a cleaning means in its path, such that said dielectric fluid can be separated from the polychlorinated biphenyls and other contaminants;   c) purifying said solution to thereby separate polycyclic biphenyls   res and other contaminants of said dielectric fluid such that said dielectric fluid can be reused in substantially pure form;   d) recycling the dielectric fluid vapor to the electrical apparatus   cudgel; and e) cooling the transformer or other electrical apparatus in operation such that the temperature and pressure   transformer or other device in operation   be kept within their operating limits.   3. A process according to claim 2, characterized in that said cooling is carried out by: a) channeling the vapor of said dielectric fluid produced by the   heat of the transformer or other electrical equipment in   from that transformer or other electrical appliance   to a condenser on his way; b) remotely transforming said dielectric fluid vapor produced by the heat of the transformer or other electrical apparatus into liquid phase operation such that the latent heat of said dielectric fluid is removed; c) recycling said dielectric fluid condensed by said condenser to the transformer or other electrical apparatus such that the transformer or other electrical apparatus is maintained at a temperature approximately equal to the boiling point said dielectric fluid.   4. Process according to claim 1, characterized in that   performs said cooling by passing said dielectric fluid through   transformer into a mechanical heat exchanger and back to the transformer so that the temperature at   the inside of the transformer can be maintained at the desired level.   5.- Method according to one of claims 1 or 3, characterized in that   said dielectric fluid is trichlorotrifluoroethane.   6. Method according to one of claims 1 or 2, characterized in that   said dielectric fluid is perchlorethylene.   7.- Method according to claim 3, characterized in that it further comprises removing polychlorinated biphenyls said means of   distillation into a waste receptacle.   8.- Method according to one of claims 1 or 2, characterized in that   that said dielectric fluid has a boiling point below the boiling point of the polychlorinated biphenyls so that said fluid   dielectric can be separated from polychlorinated biphenyls by distillate tion.   9.- Method according to one of claims 1 or 2, characterized in that   said purification is carried out by distillation of said solution by causing a vaporization of said dielectric fluid while the 17 2591383   PCBs remain in the liquid phase, and by condensing said fluid vapor   dielectric produced in said distillation.   10.- The internal parts of an electrical appliance that have been decontaminated from polychlorinated biphenyls to less than 50 ppm by the   method according to one of claims 1 or 2.   11.- An apparatus for removing contaminants such as biphenous   polychlorinated nyls of transformers and the dielectric fluid contained therein, characterized in that it comprises; a) a conduit for carrying dielectric fluid contaminated with polychlorinated biphenyls into a distillation means; b) distillation means for receiving dielectric fluid contaminated with polychlorinated biphenyls via said conduit for distilling the dielectric fluid contaminated with polychlorinated biphenyls to thereby produce a   residual amount of polybena-biphenyl contaminants   res in the liquid phase; c) a condenser in fluid communication with said distillation means and adapted to condense the vapor produced by said distillation means into a liquid phase; d) means for returning the purified dielectric fluid that is produced by said distillation and de-condensation means to the transformer while separately collecting the contaminants at based on polychlorinated biphenyls.   12. Apparatus according to claim 7 wherein there is provided a dielectric fluid, characterized by a concentration of biphenyls   polychlorinated materials contained inside the transformer.   13. Apparatus according to claim 8, characterized in that said   dielectric fluid has a boiling point below the boiling point   polychlorinated biphenyls and that polychlorinated biphenyls are soluble in said fluid.   14. Apparatus according to claim 9, characterized in that the   dielectric fluid is trichlorotrifluoroethane.   15. Apparatus according to claim 7, characterized in that it further comprises means for cooling the transformer to dissipate the heat generated by the transformer in service, such   so that said apparatus can be used while transforming is in service.   16. A process for removing polychlorinated biphenyls and other contaminants from transformers and other non-operating electrical apparatus, characterized in that the steps of removing PCBs from an electrical apparatus not in operation consist in: introducing into the apparatus is a liquid solvent having a boiling point lower than that of polychlorinated biphenyls and wherein the polychlorinated biphenyls are soluble so as to be dissolved in said solvent; - evacuate the liquid solvent from the electrical apparatus and remove polychlorinated biphenyls from said liquid; and - recycling the purified liquid solvent to the electrical apparatus   view of its reuse in this one.   17. A process for removing polychlorinated biphenyls and other contaminants from transformers and other electrical apparatus in operation, characterized in that the steps for removing PCBs from the electrical apparatus in operation consist in: - introducing into the a liquid solvent having a boiling point lower than that of polychlorinated biphenyls and wherein the polychlorinated biphenyls are soluble to be dissolved in said solvent, which solvent has dielectric properties sufficient to serve as a dielectric fluid; discharging said liquid solvent from the electrical apparatus and separating the polychlorinated biphenyls from said solvent; and - recycling said purified liquid solvent to the electrical apparatus   view of its reuse in this one.