JP2700950B2 - Vapor solvent decontamination of PCB transformer components - Google Patents

Description

Description: FIELD OF THE INVENTION Generally, the present invention relates to electrical devices such as transformers,
More particularly, it relates to the removal of residual polychlorinated biphenyl from transformer components.

BACKGROUND OF THE INVENTION Since 1929, polychlorinated biphenyls (PCBs) have been produced industrially. The outstanding properties of PCBs are thermal stable oxidation,
Includes resistance to acids, bases and other chemicals as well as excellent dielectric properties. PCB due to these properties
Fluids have been widely used in electric transformers and capacitors.

PCB toxicity has been known for decades. PCBs cause yellow liver atrophy, liver steatosis and dermatitis. Further
PCB is a putative carcinogen. In 1966, the presence of PCBs in environmental samples was discovered. A ban was issued in 1976 on the manufacture and use of PCBs in 1976 regarding the potential environmental hazards associated with the long-term stability of PCBs in the late 1960s and early 1970s [15U.SCA §2605 (e) ( 2)
(A)].

The largest residual source of PCBs is liquid-cooled transformers. The current United States Environmental Protection Agency (EP
A) According to the regulations, there are two options for the owner of a PCB-containing transformer: a retrofill or a replacement (r).
eplacement). Currently backfilling equipment is usually the cheapest and easiest for oil and Askarel ™ filled transformers.

Numerous methods effective for backfilling PCB-containing transformers, such as U.S. Patent Nos. 4,685,972, 4,124,834,
No. 4,425,949 and 4,483,717.
These methods include removal of PCB liquid, cleaning of transformers and non-PCB
The theme is liquid refilling. All of these methods are specifically directed to equipment useful for decontamination. More specifically, new regulations in these methods are often even more effective,
Or a complete method, or a method of leaving the transformer in use during decontamination. The present invention does not fall into this category of transformers.

Backfill may not be suitable for all PCB containing transformers. Is inadequate or has stopped working,
Alternatively, transformers that are no longer useful require replacement and disposal of the debris removed.

Disposal of replaced transformers has long had difficulties for owners. Current EPA regulations require that Toxic Substances C only after drainage and 18 hours of cleaning.
ontrol Act) permits disposal of PCB transformers in landfills. Although landfills are allowed, this disposal method is not without significant potential for long-term liability. Transformer debris may still contain up to 2% (20-100 pounds) of the nameplate volume absorbed into its internal structure, and the original owner will have a Comprehensive Environmental Compensation and Liability Ordinance. Response
They are jointly and strictly responsible under the provisions of the Compensation and Liability Act (CERCLA or superfund).

The present invention relates to decontamination of PCB-containing transformer components. Once the transformer has been decontaminated, its components can be disposed of as non-toxic and non-hazardous waste.

SUMMARY OF THE INVENTION The present invention comprises a method for recovering recyclable material from a PCB-containing transformer and minimizing the volume of material to comply with EPA regulations.

Drain the transformer and then do the first cleaning. The internal parts of the transformer are taken out and the second washing is performed with the transformer casing empty. Clean recoverable materials such as aluminum and copper to less than 10 μg / 100 cm ² PCB.
Thereby, these metals are reused without being buried. Almost all of the remaining non-metallic materials are flammable solids or liquids, both of which can be eliminated by incineration.

First drain any residual liquid in the PCB containing transformer. Place the drained transformer in the primary cleaning tank. The tank uses a solvent to remove the PCB from the transformer.

After the completion of this first cleaning operation, the transformer core and wire coil are separated from the transformer casing. The casing is returned to the primary cleaning tank for further cleaning by steam / spray degreasing.

The insulator on the wire coil is mechanically removed. Dismantle the transformer core. The transformer core metal components, exposed wire coils and all the various metal parts are placed in a secondary cleaning device for further cleaning.

The secondary cleaning device is a degreasing device that uses a heated solvent consisting of three separate compartments. The released parts are placed in a basket and then into the third compartment of the secondary cleaning device. The car is turned over in the secondary cleaning device. The decontamination operation consists of solvent degreasing accelerated by the mechanical action of a tumbler. The parts are processed sequentially from the third compartment of the secondary cleaning device to the second compartment and then to the first compartment. The solvent flows from the first compartment to the second compartment and then to the third compartment. As the part travels through the three compartments of the secondary cleaning device, the part is progressively treated with cleaner solvents, thereby improving the PCB removal rate.

The contaminated solvent is treated in an isothermal separator to separate the PCB from the solvent. The cleaned solvent is returned to the cleaning device for further use. Bitterns with high concentrations of PCBs are stored for future transport and incineration.

Transformer casing and dismantled parts have PCB level 1
It is processed until it becomes 0 μg / 100 cm ² or less.

The cleaned metal is regenerated because it is no longer a hazardous waste. All flammable solids, such as paper, gaskets, insulation and wood, are collected along with all PCB liquid and PCB-contaminated residue from the transformer. These flammable solids and PCB liquor are eliminated in an EPA-approved incinerator.

When the transformer cleaning operation is completed, there is no material remaining that needs to be treated by landfilling it as hazardous waste.

DETAILED DESCRIPTION OF THE INVENTION First, the PCB-containing transformer is drained of any residual liquid. Typically, one gallon or less of liquid is drained. The drained liquid is transferred to a collecting tank 10 for final disposal by incineration.

Remove the valve and cover at the bottom of the transformer. Drill a hole in the bottom of the transformer if additional drainage is needed.
Next, the transformer 31 is put into the primary cleaning tank 1.

The exterior and all accessible interior surfaces of the transformer are cleaned with a liquid solvent using a spray wand 3. The solvent is removed from the bottom of the primary cleaning tank below the temporary bed 7. After this first cleaning, the steam hose 8 is put inside the transformer, the cover 4 of the primary cleaning tank is closed, and then the heated liquid solvent supplied by the isothermal separator 9 is circulated through the transformer for 30 to 90 minutes. .

The clean solvent vapor is then circulated through the primary clean tank 1. The primary cleaning tank is operated as a steam / degreaser for 4-8 hours. The isothermal separator 9 supplies a clean solvent to the steam hose 8 through the heater 6.
The isothermal separator aspirates from the bottom of the primary cleaning tank whenever the separator requires additional solvent.
Kettle residues containing high concentrations of PCB are stored at 10 until shipped for final disposal. Additional clean solvent is supplied to the isothermal separator 9 from the refill tank 17 as needed.

The transformer casing 31 is drained and then removed from the tank after drying. Typically, this initial cleaning reduces PCB levels from the range of 600,000 ppm to around 10,000 ppm.

The transformer is dismantled and all external components, bushings,
Nuts, bolts, nameplates, etc. are removed. Internal components are also removed. Flammable materials such as gaskets, loose insulation, paper and wood are removed and stored for final disposal as PCB-containing solids.

The interior of the transformer mainly consists of a transformer core. Disassemble the transformer core to separate the wire coil from the metal laminate. Laminates, nuts, bolts and a wide variety of other metal parts are ready for a second stage cleaning in the secondary cleaning device 2.

The wire coil is coated with an insulating material that is removed by mechanical friction, such as by wire brushing. The insulation is collected for final disposal as a PCB-containing solid. The peeled wire coil prepares for the second stage cleaning in the secondary cleaning device 2.

A wide variety of metal parts, such as nuts and bolts, are placed in the fall basket 11 with the metal laminate and the stripped wire coils. Next, the overturned basket is placed on the secondary cleaning device 2. The secondary cleaning device is a heated solvent degreasing cleaning tank divided into three compartments 12,13 and 14.

The parts to be cleaned are placed in the third compartment 14 of the secondary cleaning device 2. The parts are cleaned by both the degreasing action of the heated solvent and the mechanical overturning action when the car 11 rotates. The car rotates horizontally at 2 rpm while in the secondary cleaning device. After a 30 minute cleaning cycle, the falling basket is transferred to the second compartment 13 and cleaned for 15 minutes, then transferred to the first compartment 12 and subjected to a final 15 minute cleaning cycle. A clean heated liquid solvent is supplied by an isothermal separator 15 to the first compartment 12 of the secondary cleaner. The solvent overflows from this section into the second section 13 and then into the third section 14.
This will result in parts being cleaned with increasingly clean solvents, resulting in more effective decontamination. The supply to the isothermal separation device 15 is performed in the third section 14 of the secondary cleaning device 2.
Taken out of The third compartment contains the most contaminated solvent. The pot residue with high PCB concentration is stored at 10 for future transport and incineration.

The falling basket 11 is partially immersed in the liquid solvent. A cooling coil 16 is provided in the vapor zone of the secondary cleaning device 2 to condense any solvent vapor. The condensed solvent drips into the area of the secondary cleaning device below the cooling coil.

The tumbler 11 is a hexagonal basket having six side surfaces with the wire net 21 as a side surface. A drive motor and gear assembly 24 is mounted on the outer frame 27. The drive chain 25 and the drive sprocket 26 together with the drive motor drive the inverted car 11 in the secondary cleaning device at 2 rpm.
To rotate horizontally. A hinge is attached to one compartment 23 of the falling car for access to insert or remove parts. Internal members are used to enhance the overturning action and to prevent the parts from clustering together.
member) 22 is provided.

The empty transformer shell is returned to the primary cleaning tank 1 for a second cleaning. The transformer shell is cleaned using a second spray rod 18 utilizing a clean liquid solvent supplied by the isothermal separator 9. 10-15 times each time inside and outside the transformer shell
Wash three times over a minute. Next, the solvent vapor hose 8 is put into the outer shell of the transformer, and the clean solvent vapor from the isothermal separator 9 is circulated in the primary cleaning tank 1. This steam /
The degreasing cycle lasts 4-8 hours.

After the decontamination of the transformer shell and components is completed, the surface is tested for PCB contamination. If PCB level is 10μg / 100
the part if exceeded cm ² return to the primary cleaning tank 1 or the second cleaning device 2 for additional decontamination.

In the transformer decontamination method, trichloroethylene is used as a solvent. Trichlorethylene has a low boiling point,
Selected because of 87.2 ° C (189 ° F). This low boiling point makes trichlorethylene recycling easier using isothermal separation equipment. Typically, trichlorethylene is 10
It can be kept below ppmPCB.

 The actual decontamination results are shown in the table below.

For each 125 cubic foot transformer treated, about 438 pounds of copper and aluminum, about 1275 pounds of steel casing and about 1332 pounds of steel laminate were recycled without filling. Most of the remaining PCB-contaminated solid waste (approximately 142 pounds) was flammable material that could not be buried and be lost in a licensed incinerator. About 3 liquid containing PCB during decontamination operation
Gallons were removed or produced. These PCBs could also be lost without being buried.

[Brief description of the drawings]

 FIG. 1 is a drawing of a method for decontaminating a PCB-containing transformer. FIG. 2 is a perspective view of a falling car.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor George, Earl, Green 8960 Conley Road, Kirtland, 44094, Ohio, United States of America

Claims (1)

(57) [Claims] A. Pre-washing the drained transformer by liquid degreasing using a solvent and steam degreasing; b. Dismantling the pre-washed transformer; c. The dismantled transformer Final cleaning by liquid degreasing and vapor degreasing using a solvent; d. Mechanically removing insulation from the wire coils of the dismantled transformer; and e. Removing the dismantled transformer. A method for decontaminating PCB-containing transformers, comprising: finally cleaning the internal components of the transformer, combined with its mechanical overturn, by degreasing using a heated solvent.