Removal of PCBs from transformer oils of petroleum origin

Technical Report · Wed Jan 01 04:00:00 EST 1992

OSTI ID:5854423

Rouse, T O; Fessler, W A ^[1]

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1. General Electric Co., Pittsfield, MA (United States)

Electrical insulating mineral oils in a number of transformers contain measurable amounts of polychlorinated biphenyls (PCBs). The handling, maintenance and disposal of these transformers and oils would be simplified if the PCBs in the oil were reduced to less than 2 ppm ({mu}g/g). A successful process should efficiently and reliably eliminate PCBs. In addition, the processed oil should be suitable for continued use as a dielectric fluid and it should not present an unusual problem to the environment. The goal of the project reported here has been to develop such a process. Four possible approaches seemed particularly promising initially. These were (1) liquid-liquid extraction; (2) extraction with critical fluids; (3) reaction with organo-sodium reagents; and (4) irradiation with high energy electrons. After weighing the relative effectiveness of each of the four candidates, liquid-liquid extraction -- using methyl Carbitol {reg sign} ( MeC'' -- the monomethyl ether of diethylene glycol) as the extractant -- was chosen for pilot plant evaluation. The pilot plant was operated with two unusual modifications; refluxing a portion of the still bottoms of the extraction liquid to minimize feed oil losses, and a two step solvent separation and purification process to minimize degradation of the refluxing oil from the still bottoms. Cost estimates were made for several scale-up scenarios using results from this pilot plant study. Another segment of the work was the evaluation of the reusability of oil treated by the processes considered here. These treatments did not generally harm the oils and often returned them to a condition approaching that of new oils. It does appear that, done carefully, PCBs can be removed from transformer oil by a wide range of processes, resulting in oils that are suitable for reuse.

• Research Organization: Electric Power Research Inst., Palo Alto, CA (United States); General Electric Co., Pittsfield, MA (United States)
• Sponsoring Organization: EPRI; Electric Power Research Inst., Palo Alto, CA (United States)
• OSTI ID: 5854423
• Report Number(s): EPRI-TR-100063
• Country of Publication: United States
• Language: English

Related Subjects

24 POWER TRANSMISSION AND DISTRIBUTION
240500* -- Power Transmission & Distribution-- Environmental Aspects-- (1990-)
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400105 -- Separation Procedures
54 ENVIRONMENTAL SCIENCES
540220 -- Environment
Terrestrial-- Chemicals Monitoring & Transport-- (1990-)
540320 -- Environment
Aquatic-- Chemicals Monitoring & Transport-- (1990-)
ALCOHOLS
AROMATICS
CHLORINATED AROMATIC HYDROCARBONS
COST ESTIMATION
DETOXIFICATION
DIELECTRIC MATERIALS
ELECTRICAL EQUIPMENT
EQUIPMENT
ETHERS
EXTRACTION
FUNCTIONAL MODELS
GLYCOLS
HALOGENATED AROMATIC HYDROCARBONS
HYDROXY COMPOUNDS
INSULATING OILS
MATERIALS
MINERAL OILS
OILS
ORGANIC CHLORINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
OTHER ORGANIC COMPOUNDS
PILOT PLANTS
POWER SUBSTATIONS
REMOVAL
SEPARATION PROCESSES
SOLVENT EXTRACTION
TRANSFORMERS