JPS61174705A - Replacement of refrigerant containing pcb with that containing none - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to electrical induction devices such as power transformers (elgc
trzec power transformer),
In particular it relates to dielectric liquid refrigerants contained therein and in particular to refrigerants consisting of or containing polychlorinated biphenyls PCB as a component. More particularly, the present invention converts a PCB-containing electrical induction device, such as a transformer, into a substantially PCB-free transformer, thereby qualifying the transformer as a "PCB-free" transformer under U.S. government regulations. Concerning the method of sudame.

PCB is an excellent transformer refrigerant due to its flame resistance, chemical stability, and thermal stability.
olαnt). US Patent No. 2
．． No. 582.200 discloses the use of PCBs alone or in admixture with compatible viscous modified molecules such as trichlorobenzene, and such trichlorobenzene-PCB mixtures are referred to as "askarel". a5hare
ls ) j. These askarels may contain small amounts of additives such as ethyl silicate, epoxy compounds, and other materials used as scavengers for halogen decomposition products that may originate from potential electric arcs.

ASTM D-2285-75 describes several murine askarels and describes their physical and chemical details.

However, PCBs are classified under the United States Toxic Substances Control Act of 1976.
Due to its high chemical stability, it is not biodegradable. It therefore persists in the environment and biologically expands (
It even accumulates in advanced life forms through the feeding cycle. Therefore, the United States no longer uses PCBs or Askarel liquids to make transformers. Older equipment containing PCBs is still used in some settings, but requires special equipment such as contamination protection measures and continued regular monitoring. A further disadvantage is that transformers containing pCE are prohibited from undergoing maintenance that requires removing the core from the tank;
The transformer owner is responsible for all environmental contamination, including cleanup costs for leaks, tank failures or other PCB spills, or for the release of toxic byproducts due to fire. To replace a transformer containing PCBs, (e) remove the transformer from its place of use, (2) drain the IPCB and clean the equipment as described above; (3) ) removing the equipment and installing a new transformer, and (4) taking the old transformer to an approved landfill (or solid waste incinerator). The owner of the contract will still be responsible for the transport and any future contamination problems it may cause.Liquid waste generated during replacement should be disposed of in specially designated areas. PCBs must be incinerated. Thus, transporting and replacing PCBs is expensive.But more importantly, many pure P
Since the CB or Askarel transformer is located indoors, in the basement of a building or in a particularly sealed ceiling with limited entrances, it is not physically easy to remove or install the transformer, and from a favorable handling point of view. is also undesirable.

A desirable solution to the problem would be to replace the PCB with a non-toxic compatible liquid. The new transformer has
Robert Me. Westin (Robert A, West
in) “Assessment of the Use of Selected Alternative Fluids for the PCB of Electrical Equipment”
Use of 5 selected Replacem
ent Fluidsfor pCE's in El
electrical Eqwiprnaxt'.

EpA, NTl5. PE-296577, March 1st.

1979; J., Reason (Rea50n) and W.
.

Bloomqwist, “PC
B-alternative (Replαcg?Lts): The cornerstone of the current transformer industry (FAgrg the Tra
nsformer IndustryStands n
ow) J, Power, October 1979, pp. 64-65; Harry R, Genoid
R, Shmppard), “PC in Transformers
PCB Replacement in T
ransfor-mgra) J, Block Otsu.
The am power = r y7 (proc, of
thtt Am, power Conf, ), 19
77. pp. 1062-68; Cham Week (Cham,
Weak), 1 30, 3, 24
(e/20/82)i, 4. Kara 777 (Kaw
fmar),)rm week, 130.9.5 (3
/3/82); CMR Chem Bus (Chm, Bus,
), October 20, 1980, page 26; Chttm, Eng, ), July 18, 1977, page 57; Belgian Patent No. 895,58
No. 9; Yolob Plastic News (E舊τop
, piα8-tic News) + June 1978
Many fluid types have been used, as reported in May, page 56.

These include silicone oils such as polymethylsiloxane oils, modified hydrocarbons [high ignition points, such as RTEmp, R
TE proprietary fluids], synthetic hydrocarbons (paris alpha-olefins), high viscosity esters [e.g. so-octyl phthalate and pAO-13-C, Uniroyal
Corp.), and phosphate esters. Many halodanated alkyl and aryl compounds have also been used. Among these are liquid trichlor and tetrachlorobenzene and toluene, and proprietary mixtures thereof (eg liquid mixtures of tetrachlorodiarylmethane and trichlorotoluene isomers). Liquid mixtures of trichlor and tetrachlorobenzene isomers are particularly suitable because of their low flammability (eg, high flammability point) and similar physical and chemical properties to the askarel to be removed.

Other proposed fluids include tetrachlorethylene [e.g.
mond Shα-mrock's Pgrc! gfL
g) T G ) and polyols and other esters.

Of all the non-PCB fluids, silicone oil is the most widely accepted. Its chemical, physical and electrical properties are excellent. They have a high ignition point (300℃),
There are no known toxicity or environmental concerns. These oils are trimethylsilyl-terminated with the formula %, where n is of a value sufficient to give the desired viscosity (e.g., viscosity at 25°C, about 50 centistokes). It is Tabori (trimethylsiloxane). Commercially available silicone oils suitable for use are available from Union Carbide (L-305) and others. Further, U.S. Patent No. 4,146,491, British Patent No. 1.540.158 and British Patent No. 1.589.
．． No. 435 discloses mixtures of silicone oils with various additives for improving the electrical properties of capacitors, transformers and similar electrical devices, and discloses polysiloxanes having alkyl and aryl groups other than methyl. ing.

Although it may seem simple to replace the PCB-containing Askasil in old transformers with silicone oil or one of the other alternative fluids, it is not. Typical transformers contain large amounts of cellulosic insulation material to protect electrical coils from improper contact and electrical arcing.

This material is still immersed in Askarel and may contain 3-12% of the total fluid volume of the transformer. This adsorbed askacil is not drained (drαjs);
It also cannot be flushed out by any known means, although effective. As soon as the original coarse askacil is replaced by a new non-PCB fluid, slow diffusion processes leach out the old adsorbed askasil, increasing the PCB content of the new fluid. The new refrigerant thus becomes contaminated.

For purposes of transformer classification, U.S. government regulations require s
Fluids containing PCBs of o o ppm or more are classified as “PCBs”.
A transformer containing 50 to 500 ppfi of PCB is referred to as a ``PcB contaminated transformer''.
Items containing PCBs below fi are classified as “no PCBs (nine on-
PCB) transformer. While the first two categories involve significant expense in case of leakage or the need for disposal, the last category is highly regulated by the US government. To achieve the final classification, the PC
The concentration of B must be maintained below 50 ppm for at least 90 days with sufficient energy to operate the transformer and achieve temperatures of 50° C. or higher. This corresponds to an average daily flux rate of α56 ppm over 90 days. It is anticipated that most, if not all, states in the United States will adopt regulations that are the same or more stringent than those of the United States government. There may be some lenient regulations, but...

Dow Corning Car
p, ) promotional materials, +10-205-82 "Retrosil PCB removal system (Tng Retrosil PCB removal system)"
RotnovaLSystttm) (e982)J
, and Zeo (Zero)/pC/Fo
Positive Technology Co., Ltd. (po
sttivg TeCnnolo-.

There are many commercial retrofills (
There is a retrofill J method. These are intended to carry out the initial clean drainage process as efficiently as possible during periods when the electrical equipment is not operating.

Many involve a series of flashes (fllLRh) using liquids such as fuel oil, ethylene glycol, or many chlorinated aliphatic or aromatic compounds.

Trichlorethylene is a good flash liquid. Some methods such as positive technology (pos
Z
ero) / P C / 7 Forty
The method utilizes flushing with fluorocarbon vapor alternating with liquid flushing. When the first clean drain process is complete, fill the transformer with silicone fluid. Although this might be expected to be as effective as elaborate flushing methods, it fails to remove PCBs adsorbed between the interstices of the cellulosic material.

As a result, the PCB content in the silicone refrigerant gradually increases as residual PCBs etch out during use of the transformer. Therefore, it is PCB-free (as defined by U.S. government regulations).
), 50pp for 90 days
It is necessary to periodically replace the silicone fluid or to continuously thoroughly clean it until a leaching rate of less than m is achieved.

Periodic replacement is very expensive, and because both silicone and PCBs are inherently non-volatile, their distillative separation is impractical and other separation methods are expensive and ineffective. Not on point. Dow Corning uses continuous carbon filtration in its Retrosil process to completely clean fluids.
-205-82, “Retrosil PCB removal system j (e98
2); Soyatsukeli 7-Cox (Jacqueling
Cow), “Silicone transformer fluid from Dow is p
cB4j is reduced to a single EpA group (5ilicone
TraxsformttrFlsid from
Dow Rrduces PCB Levgl
s t.

EpA 5tatLdards) J, Benoit l/ )' -Noyana/l/ (paper
Trade JolLrnal ), September 1.0 issue, 1982; T, O'Neil (0'Ne1l) and! ,
/, KgLly, [Askasil Transformer Silicone Retrofi (5iliconeRetrofi)
Ll of Askargl Transformer
s) J, Broc Elec/Electron Insul Con 7 (proc, Elec, / EleCt
ron, In51L1. Conf, ), 13.16
7~170 (e977) ;F, C, page (Pa
rn) and Michaxd, T., ``Development of a method for retrofilling transformers with silicone transformer fluids''.
sto Rstrofill Tra*sfoierg
WitnSilicotuTransformer
Liquid) J, Grokue Vri/Electron Insul Con 7, 13, 159-166 (e97
7)). Westing/-f) We s t
ingholLsg) has U.S. Patent No. 4,124,
No. 834 patented a transformer that uses a decontamination method to remove PCBs from refrigerants, while RTE describes the use of chlorinated polymers as adsorption media in European Patent No. 0.023,11. There is. However, the filters used in these methods are very expensive and are not effective in removing PCBs, both due to their selectivity and because the concentration of PCBs present is very low. Methods involving gradients in conjunction with filtration have been proposed (U.S. Pat. No. 4,299,704), but this is impractical due to limited solubility and being good only at high concentrations. Strong; also polyglycol [:F
, J, Iaconiani ((aconiαaS<), A, J
, Saggiomo and S-W. Osporn (outside Qsbor), “Removal of PCBs from Transformer Oil”
sfortnttrO8! ) j , EPRI F
(' B seminar (5gm1nar), / Ras (Da
(Llas, Texas), December 3, 1981]
Or CO, C Richard P in a supercritical state.

Defilippi (R4chard p, dttFiLi
ppi), “CO as a solvent, (COlas a
5olvent): Application to fats, oils and other substances (
Application to Fats, 0ils
and 01her Materials)J,
Chum, and Ind-
June 19, 1982, pp. 390-94] and chemical decomposition of PCBs with sodium (UK Patent No. 2,063,908). None of these methods have been found to be economically or commercially practical for Askasil transformers. However, even expensive methods make sense if it were not for the fact that the exit rate is so slow that it takes several years to reduce residual PCBs to acceptable values in the final pass. (Gilbert Azois (Gtl-b)
ert Addis) and Bear 7・o-(Ban
tss Ro), “P between transformer oil and transformer solid material
Research on CB equilibrium (Equilibrium 5
Tuesday of pcB'sBetween Tra
nsformer Oil and Transformer
rmerSolid Materials) J E
pRI PCB Seminar, December 3, 1981].

This problem and its causes are explained by L.A.Morgan.
%) and R, C, Ostra 7 (0stoff), [problems associated with retrofilling of Ascares transformers (pro
blems As5ociated with the
Rgtro-filLing of Aakare
l Transformers)J, IEEE
Power Eng
.

Soc, ), winter city, N, Y,, N, Y,
, January 30, 1977-December 4, 1977, No. 9 p.
ap, ) A77, pages 120-9.

The solubility of typical silicone oils in PCB is virtually zero (<0.5
%), while the solubility of PCB in silicone is 2
It only ranges from 10% at 5°C to 12% at 100°C. Although this limited solubility does not limit the large amount of silicone from dissolving the free PCB present, it does limit the ability of the PCB to diffuse through the pores or interstices of the cellulosic material.

Inside any hole filled with refrigerant containing PCBs, the diffusional leaching of PCBs must be accompanied by the diffusional ingress of silicone.

At some point inside the pore, there must be an interface between the PCB-containing coolant and the silicone, across which the diffusion of material cannot be very fast. PCB
Because it dissolves well in silicone, and vice versa, it slowly diffuses into silicone, and during that time, the outer shell gradually advances inside the pore.

Limited solubility limits the rate of diffusion, and although this mechanism will ultimately clean the pores of the pCE, it is orders of magnitude slower than when silicon and PCB are miscible. The high viscosity of silicones (and many other refrigerants) is also a limiting factor. The result is long-term leaching, possibly over several years, during which time the silicone must be continually filtered or replaced periodically to remove PCBs.

Thus, the slow leaching of PCBs from solid insulation by silicone is worse than without total heat leaching since the risk of spilling PCB-containing material persists for several years. Experimental studies by Morgan and Ostruff have shown, for example, that the effective diffusivity of PCBs into typical silicone oils is only a fraction of that into 10 centistoke hydrocarbon oils. Although retrofiltration of such hydrocarbon oils may therefore be preferred, even if there is no risk of hydrocarbon flammability, dirty hydrocarbon oils with high boiling points such as PCBs and silicone oils There remains the problem of separating the PCB from the PCB.

More importantly, undiluted PCB is very viscous and therefore relatively non-mobile.

Askacil contains PCB dissolved in "TCB (trichlorobenzene)" or a mixture of TCB and [TTcB (tetrachlorobenzene)" which dilutes PCB, ie reduces its viscosity. TCB is very soluble in silicone as well as PCB, so TCB is removed from the askasil in the interstices of the insulator to form a very viscous -I
The PcB (with or without a small amount of diluent TCE or mixture) is left in the gap. As a result, treatment with silicone (such as in Dow's Retrosil system) without pretreatment according to the present invention is counterproductive and makes the PCBs remaining in the interstices more difficult to remove. This explains the lack of commercial success of conventional systems that allow transformers to be reclassified to non-PCBJ status.

The present invention provides that if the refrigerant in the transformer is first replaced with a relatively low viscosity intermediate refrigerant that is miscible with the PCB, such as TCB or a mixture thereof with TTCB, the dielectric silicone oil will be It is based on the unexpected discovery that PCBs can be leached from the internal insulation of As a result, the rate of escape of PCBs into the silicone oil refrigerant is surprisingly fast when practicing the present invention and is approximately equal to the rate of escape of PCBs into the relatively low viscosity intermediate refrigerant TCB or its mixture with PCBs. Or close to it.

Past technologies first used relatively low viscosity intermediate refrigerants that were substantially free of PqB as a combination refrigerant and effluent during electrical operation of transformers or other electrical devices, followed by dielectric It has been discovered that the present invention does not disclose the concept of using silicone oil as a combined PCl3-spill resistant refrigerant during subsequent electrical operation of a transformer and then converting it to a permanent silicone oil refrigerant. There is still no prior art to suggest that silicone oil refrigerants will be relatively effective spills on PCB% after treatment with intermediate refrigerants.

More particularly, the present invention comprises a container containing a refrigerant and electrical windings including porous solid cellulosic electrical insulation immersed in and permeated into a PCB, while the PCB is connected to a transformer. A suitable temporary or intermediate leaching cooling liquid (easily a PCB and have relatively low viscosities) as an alternative to PCB-containing refrigerants. During the period of intermediate operation, the intermediate inductive cooling liquid may be changed to accelerate the effluent process; the purpose of this intermediate is to increase the effluent rate of PCBs into the intermediate refrigerant by at most 5 times the selected target rate, preferably is at most 3 times, more preferably at most 2 times. 1 With respect to US government regulations to obtain PCB-free transformers, the intermediate objective is to ensure that the rate of escape of PCBs into the intermediate refrigerant is no greater than pC83 ppm/day based on the dielectric silicone oil used as the permanent refrigerant. , preferably 0.6 to 3111111/H
For example, if the intermediate refrigerant is ITC [
3 mixture + (+-17 chlorobenzene 65-70%
and tetrachlorobenzene; (5.-30% mixture), 0.4-5 based on the weight of the intermediate refrigerant.
ppm/H]. Density of TCB mixture (e, 492) and silicone oil (0.975 for L-305) (
g/am') at 25°C, since the effluent rate is expressed in pp+* of the effluent standard, and the capacity of the effluent or refrigerant in the transformer is constant, the difference in effluent standard, e.g. TC13
Differences in PCB efflux velocity diagrams depending on mixture basis or silicone oil basis are explained. Since the density of the TCB mixture is 1.51 times that of the silicone oil, the flow rate based on the silicone oil is 1.51 times the flow rate based on the TCB mixture. To meet U.S. government regulations for PCB-free transformers, the ultimate flow rate chosen is to ensure that the PCB content of the silicone oil refrigerant in the transformer is below 50 ppm for 90 days. In, silicone oil dielectric material! Based on one view, the average PCB would have to be less than 0.55 ppm/day. The target outflow rate ultimately selected may be higher or lower than those mentioned above depending on the regulations of the area and area in which the transformer being treated resides. There may be jurisdictions and jurisdictions outside the United States that do not have regulations regarding PCB content; in such cases, transformer owners should reduce their potential liability in the event of a transformer leak. can be selected.

After the amount of leachable PCBs in the transformer has been reduced to the desired degree, the intermediate inductive cooling liquid is removed from the container and the container is then cooled with a PCB-free dielectric silicone oil compatible with the transformer. The transformer is operated until the flow rate of the PCB into the silicone oil refrigerant is less than or equal to the selected target flow rate. The dielectric silicone oil refrigerant can be modified up to many times the new dielectric silicone oil refrigerant as necessary or desired to achieve a selected target flow rate or less. No PCBl transformer after the following speed is achieved! Reclassified as a pressure vessel.

As an important g component of the present invention, the resulting transformer is PCl3
Not only does it substantially not contain T C13 or 'rT
Contains a silicone oil refrigerant substantially free of C[3.

The following describes the method of the present invention for replacing PCB fluid in a transformer with a permanent PCB-free liquid refrigerant: (e) shutting down the transformer and draining the PCB-containing fluid; and dispose of in accordance with an environmentally acceptable method. The transformer may be flushed with a flush fluid, such as trichlorobenzene or trichloroethylene liquid or vapor, to remove 1-1 PC [3 fluids].

(2) The transformer can be mixed with or dissolve a temporary or intermediate cooling fluid, such as a PCB, and can penetrate into the pores of the electrical insulation, and can also be easily separated from the PCB. Fill with available trichlorobenzene TCB or its mixture with tetrachlorobenzene and restore electrical operation.

(:() Monitor the temperature of the fluid, and if the electrical load on the transformer does not provide a fluid temperature of 1 minute to achieve the desired PCB flow rate, do not use insulation or external Heating means may be provided. Fluid may be circulated through the external loop and pump for heating purposes or to increase internal circulation.

(4) The fluid velocity of the PCB into the intermediate cooling medium can be determined by periodic sampling and analysis.

The accumulated PCBs can be removed by removing the intercooling fluid containing the PCBs and by removing the intercooling fluid such as trichlorobenzene (go CB).
) is periodically removed by distillation from PCl3. This can be done by shutting down the transformer, draining the old fluid for distillation, and replacing it with fresh intercooling fluid, such as TCB. Alternatively, leave the transformer in operation and add fresh intercooling fluid, e.g. TCB, to its opening;
and slip strcam the old rCB
Alternatively, the circulation loop h. may be removed.

(5) Distilling the PCl3-contaminated TCB fluid to obtain an essentially PCB-free TCB distillate and a TCB-contaminated PCB bottoms product. This 1゛t'': (month,
Under US government law, it can be disposed of, for example, by incineration.

(6) The flow rate of PCBs into the intermediate refrigerant is determined to a desired extent, for example, based on the heavy flow of the intermediate refrigerant as a TCB mixture, PCl 30.4 to 20. When speeds in the pps/day range are reached, the transformer is shut down, drained of the fluid, and filled with electrically conductive silicone oil compatible with the transformer.

(7) The transformer is then returned to electrical operation until the outflow rate falls below the selected target outflow rate. If this does not happen, remove the contaminated silicone oil from the PCB and continue electrical operation. 17. Monitor the temperature of this silicone oil and maintain a fluid temperature high enough (e.g., above 50°C) to ensure that the electrical load on the transformer achieves the desired high flow rate of the PCB. If this is not possible, the transformer may be equipped with a heat shield or external heating means. Fluid may be circulated through the external loop and pump for heating purposes and to increase external circulation.

(8) Electrically energize the transformer with or without replacing the silicone oil until the flow rate decreases below the selected target flow rate.

(9) To comply with U.S. government regulations for non-PC CBJ transformers, an analysis at the end of 90 days must be
Indicates PCB concentration below 0 pp@. This transformer is then reclassified as a 1°fiP CBJ.

Figure 1 shows the intermediate dielectric fluid (
PC in a real transformer in silicone oil during fJS5, 6 and 7 cycles in TCI3 mixture)
Contains prop F with a concentration ppm of l3, the vertical axis is the concentration, w
The 4th axis is the number of days elapsed (or the number of days immersed).

(TCB mixture was used for the first three cycles).

The drawings illustrate the surprising results obtained with the invention. PC with silicone oil polished for application of the present invention
The outflow rate of B is higher than expected.

r! S2 diagram shows the PCB fi degree ppm total ppm in silicone oil during 2 and 3 cycles in an actual transformer, with concentration on the vertical axis and time)-1 number on the horizontal axis scale. has been done.

FIG. 3 is a plot of the PCB concentration in silicone oil during two cycles in an actual transformer, with the concentration plotted on the vertical axis and the number of days elapsed on the horizontal axis.

The selected target flow rate of PGF2 into the silicone oil refrigerant is 50p of PCB3 fluid over a 90 day period
If you want it to be below pm, PCBo is 56 ppm/day based on the weight of silicone oil refrigerant. 5 in Figure 11
P by silicone oil as exemplified in the second cycle.
In order to take advantage of the rapid flow rate of CB without experiencing the relatively slow outflow rate of silicone oil as shown in the later stages of the 6th cycle, the conversion of the intermediate refrigerant to silicone oil refrigerant is Preferably, this is done after the flow rate into the chamber has decreased to less than three times the selected target flow rate. More preferably, this conversion takes place when the rate of exit of the PCB into the intermediate refrigerant is reduced to 2.5 times the exit rate of the selected sip. This is done when the outflow rate has decreased to approximately twice the selected target outflow rate.

Although fluid drainage and 7-lush techniques should be used effectively for the fludge process, these do not themselves constitute the invention (and are all part of previously known retrofill methods). Although they are the pre-treatments of the most effective embodiments of the present invention, their value has traditionally been overestimated: it is the slow leaching rate, and the efficiency of the flash is the limiting factor in the PC1'3 removal rate. It has been found that, in the case of fluoride, hydrocarbons such as gasoline, kerosene, mineral oil or spirits, toluene, turpentine, or xylene, a wide range of chlorinated aliphatic or aromatic R hydrogens, alcohols, ethers, Various solvents can be used, including ketones, etc. However, from the viewpoint of ease of material handling and PC
From the calculation of the separation of l3, it is practical to avoid using more species than necessary, and the intended temporary leaching fluid, e.g. i' CF3 or its mixture with tetrachlorobenzene, is initially It is most Tenkawa-like to use it.

Intermediate dielectric cooling fluids other than normally liquid trichlorobenzene TCB or its mixture with tetrachlorobenzene can also be used. Suitable intermediate fluids have the following properties: (a) are PCB compatible (i.e. preferably P
CB at 50% by weight, more preferably at least 90% by weight.
% and most preferably miscible with PCB in all proportions), but still compatible with silicone oil; (b)
having a sufficiently low molecular weight to have good molecular mobility to be able to enter the pores or interstices of the solid insulating material;
and have a viscosity of 10 centistokes or less, more preferably 3 centistokes or less, at 25°C to facilitate rapid interdiffusion; (C) be easily separated from the PCB (e.g., by distillation); and preferably 275°C or lower, more preferably 26°C
(d) currently environmentally toxic to Wc; and (e) compatible with typical transformer contents. Although T C[3, or its mixture with tetrachlorobenzene, is preferred, many alternatives as described above can be used. These include modified and synthetic hydrocarbons and various halogenated aromatic and aliphatic compounds. Furthermore, it may be a mixture of various liquid trichlorobenzene isomers.

Preferred FCB fluids are mixtures of these isomers, with or without the tetrachlorobenzene isomer5; the advantage of this is that such mixtures have a lower freezing coefficient than the individual isomers; Thus, in very cold climates C also lies in the fact that it reduces the solidification of solids within the transformer. Furthermore, mixtures are often usually I11! It is the result of the construction method,
Therefore, it may be less expensive than separated and purified individual isomers.

However, any solvent in which PCl3 is dissolved may be used for flashing and as an intermediate dielectric cooling fluid for leaching of PCBs contained within the transformer. Examples of chlorinated solvents such as trichloroethylene, trichloroethane, tetrachlorethylene, tetrachloroethane, chlorinated toluene, chlorinated xylene, liquid trichlorobenzene and its isomers and mixtures, and liquid tetrachlorobenzene and its isomers and mixtures. Mixtures are suitable. Hydrocarbon solvents such as gasoline, kerosene, mineral oil, mineral spirits, toluene, turpentine and xylene can also be used, but are considered too flammable +lJ for safe use. Particularly suitable solvents are characterized by their low flammability properties,
Trichlorobenzene and tetrachlorobenzene are preferred because of their high PCB affinity and their ability to circulate within the transformer vessel and enter the pores or crevices of solid insulation materials.

Since the preferred objective here is to leach the PCBs at the fastest practical rate, the preferred embodiment is that the PCBs are in the intermediate refrigerant according to step (3) above and in the dielectric silicone oil according to step (7) above. This includes activating a transformer to maximize the rate of diffusion into the air. When used at its full rated load, the transformer should automatically provide sufficient heat for this purpose. However, since many transformers are operated below their rated load and below their rated safe temperature (70-110°C), a sufficient temperature rise (e.g. at least 50°C) must be achieved by means of heat protection. or may not be achievable without external heating means. Although this temperature control represents a preferred embodiment of the invention, it is optional and not a requirement. This is because there are many transformers for which such insulation or heating is impractical. Leaching at lower temperatures, for example at ambient temperature, can be done but will take longer.

Circulation of the fluid as specified in steps (3) and (7) is optional, but is an advantageous embodiment in that such circulation prevents the formation of concentration gradients that serve to retard diffusion. . Since runoff is a slow process, the circulation rate does not need to be very fast. Of course vigorous cycling should be avoided to avoid damage to the internal structure of the transformer. Many transformers, due to their construction or arrangement, cannot be easily modified to use circulation loops, and such circulation is only one embodiment of the present invention for increasing drain velocity, and as a necessary aspect. It should be recognized that this is not considered. In many transformers, the natural thermal gradient alone will be sufficient to induce circulation, especially when using relatively low viscosity, mobile refrigerants such as TCB.

As the PCB content in TCB or other intermediate refrigerants in transformers or in silicone oil dielectric refrigerants builds up,
It ultimately reaches a point where diffusion is no longer useful in leaching the PCBs out of the pores or interstices of the insulating cellulose within the transformer tank. A decrease in flow rate as determined by sample analysis is an indication that this is occurring. Once it has been determined that this is happening, the process (
4) and (7), the PCB loaded intermediate dielectric cooling fluid or dielectric silicone oil should be removed from the new PCB.
It will be necessary to replace it with a fluid or oil that does not contain B.

This is most easily accomplished by shutting down the transformer, draining the dirty leach fluid (intermediate dielectric refrigerant or silicone oil), and replacing it with fluid or oil.

In practical cases, it is better to remove the transformer than to monitor the effluent rate to determine when diffusion no longer serves to effectively leach PCBs from the pores or crevices of the electrical insulation. It is more practical to change the refrigerant regularly according to a schedule. If a PCB-free transformer is desired, the refrigerant
The refrigerant is replaced after the selected period of electrical operation until no more than 50 ppm (based on silicone oil refrigerant) of PCBs is expelled after one day of operation. The period of electrical operation between refrigerant exchanges is between 20 days and 1 year (or when the transformer owner has shut down the transformer except for rare specified periods, e.g. during special holidays). (for more than one year, sometimes longer if suspended annually);
Preferably 30-120 days, most preferably 45-90 days
You can choose the day.

The dirty leach fluid is then distilled and condensed for reuse, leaving the PCBs as a bottom residue, which is incinerated or disposed of in accordance with U.S. government regulations.6 Although complete replacement of the intermediate refrigerant is preferred, , further equipment stoppage is inconvenient,
Different methods are possible, namely to operate the transformer while simultaneously introducing new fluid and removing old dirty fluid.

Similarly, silicone oil loaded with PCBs can be continuously removed from the transformer, while new PCB-free silicone oil can be continuously introduced simultaneously at intervals. This reduces efficiency as the new fluid or oil mixes with the old in the transformer, and the fluid or oil with reduced PCB concentration is actually removed. Therefore all PCB
In order to eliminate this, a larger amount of leach spill or oil would have to be removed than would be the case with the preferred method.

This disadvantage can be reduced if efforts are made to avoid excessive mixing. For example, new cooled TCB or other intermediate dielectric cooling fluid is introduced to the bottom of the transformer, while warm P
The CB loaded intermediate dielectric cooling fluid may be removed from the top. Differences in density will slow down mixing. Similarly, new chilled silicone oil (relatively more dense)
is introduced into the bottom of the transformer in step (7), while warm PCB loaded silicone oil (relatively lower density)
remove from the top. Regardless of the method used, this process requires repetition until the desired PCBfi in the silicone oil is achieved. Although distillation is the preferred method for separating TCB or other dielectric refrigerants and PCBs, other methods are possible, especially if a fluid other than TCB is selected as the fugitive fluid. PCBs may be removed from the PCB-laden silicone oil in step (7) (e.g. during operation during step (7) or stopped after removing the PCB-laden silicone oil) ), PCBs can be removed by contacting them with activated carbon, zeolites, or other adsorbents that can adsorb them from silicone oils. Any other method for removing PCBs from used silicone oil can also be used.

TCB itself or other chlorinated intermediate dielectric refrigerants,
For example, TCB and other halogenated solvents may ultimately become suspected of being hazardous to health, and transformers should not be contaminated with TCB or other objectionable intermediate fluids. There is interest in this. A further advantage of the method of the invention is that not only does the transformer in the ultimate of the method of the invention not contain objectionable amounts of PCBs, but also TCB or any other potentially objectionable intermediate fluid. This means that it does not substantially contain. Thus, the intermediate refrigerant can be replaced and the old batch sent to distillation in the refining pool, and the initial charge of silicone oil can be replaced and the old batch sent to distillation for refining.

The final filling of the transformer is preferably carried out with the same silicone oil used in the previous silicone oil leaching step, for example step (7). Other silicone oils may also be used in steps (f) to (j) of the claimed invention and in steps (6) and (8) of the more specific embodiments described above. Suitable silicone oils have the general formula (C112,)zsiO[(C1lz)2
siO]n5i(CHl)z (Formula ^) [where n is a viscosity that provides the desired viscosity (preferably 20 to 200 centipoise, more preferably 30 to 100 centipoise, most preferably 45 to 75 centipoise at 25°C) is sufficient for .

Other permanent refrigerants, rather than silicone oil, may be used for the final filling of the transformer.

Other suitable refrigerants of a permanent nature that may be used in place of the final silicone oil charge are dioctyl 7-thaletate,
modified hydrocarbon oils such as RTEmp from RTE; polyalphaolefins such as PAO- from Uniroyal;
Permanent dielectric fluids, including 13-C, synthetic ester fluids, and any other compatible permanent fluids, are preferably characterized by relatively high boiling points compared to the dielectric solvent and are therefore not required. and transformer enclosure (e.g. tank)
The open dielectric solvent can be separated from the permanent fluid to avoid release of the permanent fluid by evaporation when it breaks down.

Although the following final fill permanent dielectric fluids have been proposed and in some cases used, they are less preferred than relatively high viscosity, high boiling point permanent dielectric fluids. Tetrachlorodiarylmethane, 7 leone, halogenated hydrocarbons, tetrachloroethylene, trichlorobenzene isomers and tetrachlorobenzene isomers with or without trichlorotoluene isomers. Trichlorobenzene isomers, tetrachlorobenzene isomers, and tetrachlorobenzene isomers, and mixtures thereof, have high flammability ratings and other physical properties similar to 7 scalels, and are therefore less suitable for permanent fluids. Among them, it is suitable.

An illustrative example follows. Each of the examples represents actual treatment of actual transformers, and the data presented in Table 1jIJ1 consists of or is based on data actually obtained during treatment of these transformers. In the examples, the following abbreviations will be used.

TCB) Lichlorobenzene TTCB Tetrachlorobenzene TCB Tetrachlorobenzene TTCB30-35i
i1% and trichlorobenzene'I'' CB 70-65% by weight (contains an effective amount of an epoxide-based inhibitor to scavenge chlorine) PCB Polychlorinated biphenyls ppm PCBs per million parts of refrigerant by weight
or part of TCB or TCB mixture Ascacil 70 A roclor 1260
Askacil type A Aroclo 1260 polychlorinated biphenyl (chloride 6
0% by weight)' L-305 A silicone oil within the range of formula (A) above having a viscosity of 50 centistokes at 25 DEG C. A "cycle" is a period of exchange of refrigerant. A "portion" of a cycle is a portion of the cycle in which the rate of evacuation into the refrigerant is significantly different from the rate in earlier or later portions of the cycle.

1.2, 3, 4.5 Upstream A Table 1 shows summary data for six transformers. The transformers for Examples 2.3 and 4, designated as #460, #461 and #459, respectively, had a capacity [333 KVA
Three identical 7 butegra 7 (U pLegrarr
) A series of transformers electrically linked so that the loads are equally distributed.

Each of these transformers is powered by mineral oil [Exxon Unipol] (
Exxon U n1 Volt) inhibitor oil, transformer grade] containing approximately 159 lbs. They were at one time filled with askacil, but this was subsequently replaced with mineral oil. At this time they contained the amount of residual PCBs shown in the table. Example 1. designated as #667, #668 and #669, respectively. The transformer for A and 5 is capacitor 113
a similar series of three identical transformers of 33 KVA, similarly connected, but in this case Westinghouse transformers;
7 scalerels of type A (60% of 70 clos 1260 and T
Each contained approximately 190 gallons of CB40%). These transformers were expected to be the most difficult to leak.

They are coil-wound transformers, with paper insulation, and diffusion path lengths that can be several inches deep.

All six transformers are shut down, drained and then rinsed and filled with refrigerant for Cycle 1 as shown in Table 1. These were then turned on and allowed to run normally with leaching. Samples of this fluid were taken periodically for analysis. Table 1 shows the results of these analyzes at the end of the leach cycle portion. The table also shows the temperature of the fluid during the leaching cycle; the typical loads required on these transformers were considerably lower than their rated capacity and therefore the typical operating temperature was also low (50°C or less).
. Higher temperatures were achieved by installing cooling vanes and in some cases wrapping heating tape. Table 2 provides further detailed data for subsequent cycles of these transformers, particularly for L-305 silicone oil to solvent cycles. If the silicone solvent is rCB or 'C
When reverse leaching from the B mixture, these data are also shown in Table 2.

Example 1 #667 illustrates the present invention. The transformer was drained of the 7 scalels, the transformer was rinsed with the TCB mixture, and the transformer was filled with the TCB mixture. The initial leaching rate is mainly due to the remaining unrinsed liquid and the PCB (
ie in coarse or shallow insulation) are the most easily leached and therefore faster, while after about 50 days the rate becomes very slow.

Average data for cycles 2, 3 and 4 are shown in Table 1. When cycle 1 was conducted under atmospheric conditions, the transformer was heated to 55°C for cycle 2 and 85°C for cycles 3 and 4. The average leaching rate for cycle 4 was 4.78 ppω/day (L-
305 standard), but due to the curvature of the leaching curve, the rate at the end of the cycle was approximately 2.5 ppm/7 days, and 0.55 ppm/day for reclassification to PCB-free status.
It was slightly less than 5 times the target leaching rate for the day. This is shown in FIG.

Figure 1 shows the accumulation of PCBs in the solvent for cycles 4, 5.6 and 1/7. For cycle 4, the solid line is T C
The analysis results in ppa+ (by weight) of PCBs in the B mixture are presented, while the S line represents the same amount of PCBs converted to L-305 solvent basis. (Analysis data for other cycles with L-305 as solvent are automatically referenced to L-305.) Recognizing that silicone oils typically leach 7 scaleels at a much slower rate than 1' CB mixtures; Based on consideration of the fact that the transformer was previously artificially heated, it was expected that replacement of the refrigerant with L-305 silicone oil would give a sufficiently low leaching rate for reclassification. However, surprisingly it has been discovered that this does not occur. Even with reduced heating, L-305 initially leached faster at the end of cycle 4 than in the case of the TCB mixture (2.5 ppm/day) (6.06 ppm/day), followed by that at the end of cycle 4. Approximately equal steady speed (2,38 pp
a+/day). This is also shown in the $1 figure. It has been found that this unexpectedly high speed means that additional PCBs are leached out, resulting in a cleaner transformer.

To speed up this leaching, the transformer was reheated to 85°C. (This reheating coincided with a rapid increase in PCBs in the refrigerant around day 370 of cycle 5.

) Overall average leaching rate in cycle 5 is 3.33 pp
m/day. The transformer was drained again and filled with fresh L-305 on day 390. cycle 6
The average rate during was 0.86 ppu/day, and new L305 final refrigerant was introduced on day 524. With the artificial heating removed, the transformer could be reclassified as PCB-free after 91 days. In actual use, the three cycles of L-305 can be achieved by combining cycles 5 and 6,
Therefore, only one batch of L-305 was needed for the "preliminary" leaching and was therefore contaminated with PCBs.

The unexpectedly high leaching rate into L-305 requires one or more r-preparative L-305 leaching cycles, and therefore, e.g.
October 161, 984 - (7 Esler (Fers)
ler U.S. Pat. No. 4,47''7,354], by adsorption, extraction, or chemical means).
This also allows most of the intermediate solvent of the TCB mixture to be removed from the transformer. f! S2 table is TC
Further details regarding the L-305 cycle are shown, including the reverse leaching of the B mixture. Table 2 shows that the final charge of permanent refrigerant contained only 0.038% TCB or TTCr3, while the 5-port cycle contained 4.5% chlorinated compounds. Table 1 also shows that the amount of PCl3 in the TCB mixture at the end of cycle 4 is 351 ppm.
(e, total W from 530 on -305 basis), while at the beginning of cycle 5 the ratio of outflow of PCB and TCr3 mixture (fIS2 table) was 6.06/3375, or TC[31800 ppm PCI in the mixture It also shows that it is equal to Thus, the high velocity could not be fully explained on the basis of the residual liquid left behind in cycle 4.

TCB with a higher concentration of PCBs than the cycle 4 liquid
The mixture was clearly leached. Here, PCBt-T
It is clear that treatment with the CB mixture gives faster leaching with b1L-305 than would be expected based on the normal differences in leaching agents.

Example A is a symmetric example in which Askacil was not treated with the TCB mixture prior to leaching with L-305. Let Askasil wander from transformer #668,
Rinse this by spraying with L-305, and then use a new L-305 spray.
Filled with -305.

At the end of the 392nd day, the transformer was emptied again and rinsed with a spray of L-305, then filled with fresh L-305 and operated as cycle 2 until day 539. At the end of cycle 2, it was still leaching at a rate of about 11°6 ppm/day.An important illustration of this example is that L-30
5 alone did not provide a reduced leaching rate within a reasonable period of time. The leaching rate during the first 28 days of cycle 1 was comparable to the initial leaching rate for #667 and V#669, indicating removal of the easily leached portion of the contained PCBs, but the rate was
8, and over 500 days 6
~llppm/day continued (cycles 1 and 2
). TCB compound filled transformer #667 & V #66
9 leached substantially more in the first 96H than L-305 filled transformer #668 leached in 392 days. The effluent rate in each of transformers #667 and #669 decreased as the contained PCBs gradually depleted.

Example 2. Pour 4# of $460 liquid, rinse, TCB (
Refill with TCB mixture 1). At the end of cycle 1, the leaching rate of PCB is 1. O2ppm decreased in 7 days,
Therefore, drain it, rinse it with L-305, and rinse it with L-305.
Refilled with 305. As in the case of $667,
The leaching rate of PCBs increased dramatically, extracting significantly more PCBs than expected with L-305 in the first 10 days. This is illustrated in Figure 2, where the concentration of rcn also increased dramatically (table #2), more than could be explained solely by the residual *unliquified liquid.
By today, the PCl3 outflow yA degrees had decreased to 0.12 ppn/day. This refrigerant was drained and a new L-30
5 was substituted. PCBfi on day 92 of cycle 3 is 5
．． With only 5 ppm, this transformer could be reclassified as PCB-free. a The TCB content in the final refrigerant was only 0.378%.6 Comparing Example 3 to Example 2, #461 was leached with the TCB mixture for two cycles. It leached at a rate of only 0.24 ppm/day when replaced with L-305. Therefore, only one cycle of L-305 was required to reclassify to PCB-free status. However, the remaining chlorinated compounds in the refrigerant amounted to 4.72%, which required another L-305 cycle if it was desired to remove them. In this case, L-3 for the second cycle.
L for PCBs using 05 and treated with TCB
It was effective to take advantage of the good leachability of -305.

Example 4. #459 tested 7 other environments in which the leaching rate was reduced to very low values before introducing L,-305.
1'z. As a result, it was possible to reclassify the L-305fi final refrigerant in one cycle.

However, pcB and soybean were rather high at 37 ppm. Preliminary 1. -: (Although leaching at 05 is not necessary in this particular case, the transformer showed an unusually fast leaching with the intermediate refrigerant, namely L-305 of the PCB treated with the substrate of the present invention. is illustrated in Figure 3. Example 4 represents the potential for environments where mineral oil is used as an intermediate solvent, i.e. for transformers that do not fall under strict flammability hazard regulations. Normally L if no changes or changes in the regulations applicable to the area are anticipated.
The final charge of L-30,5, which will not be replaced by -305, is expected to contain a few percent of mineral oil from the previous leaching cycle, which probably increases the ignition point of the cold refreshment required for special conditions. This will be sufficient to reduce the temperature below the ignition point. Therefore, in such a case, it seems that further refilling of -305 is necessary.

Mineral oil is thus a suitable intermediate solvent for transformers placed in locations where fire is not strictly a hazard. Although it cannot be easily separated from PCI3 as l' CI3 or rc Extraction is also possible.

Example 5. $669 was processed in the same manner as #667. However, it operated at a lower temperature than the second and third cycle Nakai 667 and therefore progressed more slowly. For this reason, and in order to get closer to the target of 0.55 ppl/day, before replacing L-305 or other final refrigerant into the first cycle, it was leached with the TCB mixture. Therefore, at this time, this is only a partial illustration of the implementation of the present invention.

1st Example Equipment description Initial PCB concentration Solvent (refrigerant) used Temperature °Cli--Logic w-1--- 1 Transformer #667 600,000 Askasil cycle 1, 1st part TCB
Mixture var(40) Cycle 1, 2nd part
T CB tn compound var (40) cycle 2 TCB mixture 55 cycle 3
TCB mixture 85 cycles 4
TCB mixture 85 cycles S
L-30540
,85 cycles 6
L-30585 cycle 7
L-305war-556Reclassified as PCB-free in 15 days 2 Transformer #460 25,000
Mineral oil cycle 1, 1st part TCB
85 Cycle 1, Part 2
TCB 85 cycle 2, 1st portion L-30585 cycle 2, 2nd g portion L-30585 cycle 3 L-305v
Reclassified as PCB-free in ar~55375 days 3 Transformer $461 7.800
Mineral oil cycle 1, 1st part TCB
Mixture 85 Cycle 1, Part 2
TCB Mixture 85 Cycle 1, Part 3
Effluent TCB mixture 85 cycles 2
, first part TCB mixture 8
5 Cycle 2, 2nd part TCB mixture 85 interval days PCB concentration at end
Leaching speed N rank Rainbow Pressure ≦? 051i+*
) m/day L-305 standard) 0 50 1
2.000 240.0050 9G
14. GOOS6.0096 161 1.
200 18.50161 225
600 9.38225 336
530 4.78336 39
0 180 3゜33390
524 115 0.8652
4 615 23 0.25
0 25 750 30.0
025 162 B2O1,021631?
3 45 4.50173 2
B3 58 0,12283
375 5.5 0.060
25 650 26.002
5 68 820 3.95
68 164 1.140 3.
33164 175 68 6
．． 18175 284 94
0.24th 11℃ Di11) Equipment description Initial PCB concentration Solvent (refrigerant) used
Temperature ℃ Every other day - Tomo - Kazuichi
-Sako Musume Transformer #459 9,150
Mineral oil cycle 1, 1st part Mineral oil 85 0 cycle 1, 2nd part
Mineral oil 85 115
Cycle 2, 1st part L-305
85224 cycle 2, second part
L-30585255 cycle 2, ttS3 part
L-305war-5529038 Reclassified to PCB-free in 1 day Transformer 169 600,000 Askasil cycle 1, 1st part TCB mixture var(40) 0 Cycle 1, 2nd part
TCB mixture var(40)
50 cycles 2, TC
B mixture var (e5-40) 96 cycles 3
TCB mixture
55 161 cycles 4
TCB Mixture 85 225 Cycle 5, Part 1 TCB Mixture
85 294 cycle 5, second part
TCB Mixture 85 360 Ongoing Transformer #668 600.000 Askasil Cycle 1, 1st Part L-3
05war (40) 0 cycles 1, 2nd part
L-305war (40) 28 cycles 2 L-3
0585392 Number in progress PCB concentration at end Leaching rate 1
Capture “Uni 1-q” 131! Q-91117th L-
305 groups 115 392 3.
41224 423 0.28
255 27 0.8729
0 30 0.09381
37 0.0B50 1
1.300 226,0096 13.
000 37.00161 68
0 10.50225 830
13.00294 390
5.65360 453
6.86606 770 1
．． 2928 8.650 309.0
0392 11.900 8,385
39 1.700 11.60 Transformer Interval days Average PCB outflow rate Example
pp export/day 8] 2 □ 1 667, cycle 5 336-344
6.0f3344-370 2.38 370-390 3.25 Cycle 6 390-396 2.5039
6-420 1.17420-445
0.75 445-524 0.67 cycle 7 5
24-615 0.252 460, cycle 2 162-169 5.64169-
185 0.49 185-220 0.18 220-283 0.12 Cycle 3 283-375 0.063
461, cycle 3 284-376
0.124 459, cycle 2 290-381
0.085 669, cycle 5 296
-350 3.91350-400
3.93400-606 1.76
A 668, cycle 1 0-28
30928-242 10.6 cycle 2 392-539 11.6 pieces
L-305 standard Kimoto: Is TCB still a refrigerant?Here, the extracted TCB or 1:TCB in L-305 Average TCB or or TCB mixture Outflow rate of TCB mixture 3*-1--- 2.70 33753.61
3504.51
4500.16 2670.
31 61.30.34
11.60.038
4.26.35 90717.
33 6137.72
1110.378 4
1 4.72 513-one book
-111 books -11 books
- 1 Kyoto book 11 book
-Ippon 1.48526 1.647.85: No TCB mixed proboscis.

Fire 74jL Nishin silicone oil is virtually insoluble in chlorobenzenes, which, on the contrary, is only slightly soluble in silicone oil (for example, a TCB mixture has about 28
% by weight), the leaching of chlorobenzenes or PCBs within the pores due to the penetration of silicone oil into the interstices or pores containing the chlorobenzenes must involve the interface,
Although not bound by theory, the existence of two types of mechanisms can be postulated. i.e. capillary displacement or outflow when the hole is open at both ends and chlorobenzene e.g. PCB and/or TCI3 and V/or TTC when the hole is open at only one end.
Diffusion mechanism when B diffuses into silicone oil and the interface moves into the pores.6 The purpose of the present invention is to illustrate the rate of migration of the interface into the pores.

This example utilized an apparatus comprising a glass tube capillary with an inner diameter of 211III extending downwardly from the bottom of a glass container with a stopper. The lower end of this capillary was closed and the upper end opened into the interior of the glass container. The capillary held 0° 125 cc when filled, and the lath vessel was approximately 15 cc. A millimeter eye) was attached to this capillary. In each of Runs #1-12, the lower phase as shown in the f53 table was introduced into the capillary tube and filled to approximately . The upper phase as shown in Table MS3 was then placed in the top 18 of the capillary tube in a glass container. The initial position of the interface between the upper and lower phases was measured, and the position of the interface was measured on a daily basis to determine the rate of downward movement of the interface. The rates shown in Table 3'R for runs #1-6 were determined over a 35-40 day period, and the rates shown in Table 3 for runs #7-12 were measured over a 20 day period.

It is noted that the ratio of the velocity for the TCB mixture and the velocity for the 7-scalel was independent of temperature (approximately 2).
0), the data shown in 3rd fi also illustrate that the rate at 60°C is approximately 1°5 times that at 40°C, and also does not appear to increase proportionally further at 100°C. . Table 3 also shows that the penetration rate of TCB into the silicone oil is greater than that of the TCB mixture, which in turn is greater than that of Askacil. The results of experiment #6 also suggest that the back-diffusion of TCB from the upper phase to the lower phase is due to the very low diffusion rate found for real ##6. The back-diffusion in experiment #4 did not significantly affect the rate since the lower phase was approximately 100% TCB, whereas in experiment #6 the lower phase contained 40% TCB.
It contained only %.

The first conclusion above, i.e., the TCB mixture is 7-scalel L-
The fact that L-305 flows out twice as fast as with L-305 is the key finding behind using pre-leaching of L-305 (e.g. cycle 2 of Example 2 and cycle 5 of Example 1). ).

L-305 effluxes Askacil itself slowly, but once the latter is diluted with the TCB mixture, the TCB mixture containing PCBs can be effluxed very quickly. This results in loading and no PCBs in the final silicone oil by removing substantially all of the TCB mixture by leaching with the final L-305 and removing many of the PCBs that could not be leached with the TCB mixture itself. Enabled reclassification as a transformer.

The invention may be used in any electrical induction device using a dielectric coolant liquid, including, but not limited to, electromagnetic, liquid cooled motors, and ballast resistors used in WtIL devices such as fluorescent light sources. can.

[Brief explanation of the drawing]

Figure 1 shows the intermediate dielectric fluid (
Concentration of PCBs p in the actual transformer in silicone oil during the 5th, 6th and 7th cycles in TCB mixture)
Contains a plot of p-, where the vertical axis is the concentration and the horizontal axis is the elapsed days (or immersion days); Figure 2 shows the PCBs in silicone oil during 2 and 3 cycles in an actual transformer. Figure 3 is a plot of the concentration in silicone oil during two cycles in an actual transformer, with concentration on the vertical axis and elapsed days on the horizontal axis. The PCB concentration is plotted, with the concentration on the vertical axis and the number of days elapsed on the horizontal axis. Patent Applicant: Union Carbide Corporation

Claims (1)

[Claims] 1. A PCB-containing refrigerant, an electrical winding, and a porous solid cellulosic electrical wire immersed in the PCB-containing refrigerant, but initially impregnated with the PCB-containing refrigerant. In an electrical induction device having a vessel containing an insulator, the refrigerant is supplied with a substantially PCB-free, high-boiling, dielectric material that flows into the device at a rate no greater than the selected target. In replacing the refrigerant with a permanent refrigerant, (a) remove a major portion of the refrigerant contained in the container; (b) fill the container with an intermediate dielectric cooling liquid that is substantially free of PCBs, but a cooling liquid (i) is miscible with the PCB-containing refrigerant; (ii) has a sufficiently low viscosity to circulate within the container and penetrate the interstices of the porous solid insulation;
and (iii) can be easily separated from a PCB; (c) electrically actuating the electrical induction device to remove a PCB contained in the refrigerant impregnated in the porous solid insulator;
into the intermediate dielectric cooling liquid; (d) then removing the intermediate dielectric cooling liquid containing the spilled PCB from the container; (e) discharging the electrically actuated liquid following step (c) then steps (b), (c) and (
repeating the cycle of d) a sufficient number of times until the exit rate of PCBs into the intermediate dielectric cooling liquid does not exceed five times the selected target rate; (f) cooling the container; filling with a substantially PCB-free dielectric silicone oil as a liquid; (g) electrically actuating the electrical induction device containing the PCB-free dielectric silicone oil cooling liquid; (h) then draining the dielectric silicone oil containing the spilled PCBs from the container; (i) if the flow rate of PCB into the dielectric silicone oil exceeds the selected target flow rate;
repeating the cycles of ), (g), and (h) for a sufficient number of times such that the flow rate of PCB into the dielectric silicone is less than or equal to the selected target flow rate; and (j) refilling the container with a substantially PCB-free permanent dielectric liquid;
A method of replacing the refrigerant with a dielectric permanent refrigerant with a high boiling point that does not contain B. 2. Perform step (c) for 20 days to 2 years and repeat the cycle defined in step (e) until the flow rate of the PCB into the intermediate dielectric cooling liquid after electrical actuation following step (c) is If the PCB is in the range of 0.6 to 3 ppm/day based on the weight of the permanent refrigerant, repeat and step (q)
The method according to claim 1, which is carried out for a period of 1 day to 2 years. 3. The cycles of steps (b), (c) and (d) are performed on a PC.
Step (1) until the rate of flow of B into the intermediate dielectric cooling liquid is in the range of 1 to 3 times the rate of flow of B into the refrigerant of a selected target electrical device rated as PCB-free. e
), the method according to claim 1. 4. The cycles of steps (b), (c) and (d) are performed on a PC.
Step (1) until the exit rate of B into the intermediate dielectric cooling liquid is in the range of 1 to 2 times the exit rate into the refrigerant of the selected target electrical device rated as PCB-free. e
), the method according to claim 1. 5. The method according to claim 4, wherein each step is continued for 30 to 120 days. 6. When performing step (d) of the previous cycle and step (b) of the next subsequent cycle, the intercooling liquid is removed from the top of the vessel while fresh cooled intermediate dielectric cooling liquid is added to the vessel. 5. The method of claim 4, further comprising supplying the bottom of the device and continuing electrical operation of the device. 7. When performing step (h) of the previous cycle and step (f) of the next subsequent cycle, the dielectric silicone oil cooling liquid of the previous cycle is removed from the top of the vessel while the new cooled dielectric 5. The method of claim 4, further comprising supplying a silicone oil cooling liquid to the bottom of the container and continuing electrical operation of the device. 8. to increase the temperature of the intermediate dielectric cooling liquid contained in the container during each step (c) or to increase the temperature of the dielectric silicone oil cooling liquid contained in the container during each step (g); 5. The method of claim 4, wherein the container is provided with a thermal barrier while the electrical induction device remains electrically activated. 9. Transfer the intermediate dielectric cooling liquid contained in the container to each step (c
) or heating the dielectric silicone oil cooling liquid in the container during each step (g), during which the electrical induction device is kept electrically activated. . 10. The intermediate dielectric cooling liquid during step (c) or the dielectric silicone oil cooling liquid during step (g) is removed from the container, heated, and returned to the container, while maintaining sufficient dielectric 5. The method of claim 4, wherein a sexual fluid is maintained in the container and the electrical induction device is electrically actuated. 11. The intermediate dielectric liquid is more volatile than the PCB, and the P contained by distillation of the intermediate dielectric cooling liquid
5. A method according to claim 4, wherein the method is separated from CB. 12. removing the PCB-containing intermediate dielectric cooling liquid that has flowed from the solid insulator from the vessel as a wake during step (c), and the amount of PCB-containing intermediate dielectric fluid being removed in the wake; 5. The method of claim 4, wherein a fresh PCB-free intermediate dielectric cooling liquid substantially equal to: is added to the container. 13. The dielectric silicone oil cooling liquid containing PCBs that has flowed from the solid insulator is removed from the container as a slipstream during step (g), and a new volume substantially equal to the amount removed in the slipstream is removed from the vessel during step (g). 5. The method of claim 4, wherein a dielectric silicone oil cooling liquid is added to the container. 14. The container is treated with the P after step (a) and before step (b).
Claim 4 Flushing with solvent for CB
The method described in section. 15. The method of claim 14, wherein the flashing solvent is the same liquid as the intermediate dielectric cooling liquid used in step (b). 16. The method of claim 4, wherein the container is flushed with a dielectric silicone oil cooling liquid after step (h) and before refilling the container. 17. The method according to claims 1 to 16, wherein the intermediate dielectric cooling liquid is trichlorobenzene. 18. The method of claims 1 to 16, wherein the intermediate dielectric cooling liquid is a mixture of trichlorobenzene and tetrachlorobenzene. 19. The method according to claims 1 to 16, wherein the intermediate dielectric cooling liquid is trichlorethylene. 20, the dielectric silicone oil cooling liquid has a temperature of about 50°C at 25°C.
17. The method of claims 1 to 16, wherein the oil is a poly(dimethylsiloxane) oil having a viscosity of centipoise. 21. The method of claims 1 to 16, wherein the substantially PCB-free permanent dielectric liquid used in step (j) is a dielectric silicone oil. 22. Selected target outflow rate is 90 without changing refrigerant.
17. A method according to claims 1 to 16, wherein the concentration is 50 ppm after being electrically operated for one day. 23. The dielectric silicone oil cooling liquid has the formula (CH_3)_3SiO[(CH_3)_2SiO]_
nSi(CH_3)_3 [where n is 2 at 25°C
17. A method according to claims 1 to 16, wherein the poly(dimethylsiloxane) oil has a value sufficient to provide a viscosity of 0 to 300 centistokes.