Real-Time Transformer Oil Polychlorinated Biphenyl Sensor
EPA Phase II SBIR Contract EP-D-07-082
Polychlorinated biphenyls (PCBs) remain a significant environmental threat, even though manufacturing of PCBs was discontinued 30 years ago. Due to the chemical and thermal stability of PCBs in the environment and the continued use of transformers containing these chemicals, specific regulations are in place that require quantification of PCBs in transformer oil. The Toxic Substance Control Act mandates that the concentration of PCBs in transformer oil to be less than 50 parts per million. PCB concentration analysis is currently performed in an analytical lab using gas chromatography with SW-846 Method 8082 standard method. This type of analysis is time-consuming and costly; in addition, the oil must be removed from the transformer, which potentially exposes workers and the environment to PCBs. Eltron is developing a new, portable real-time sensor that can be used on-site to not only quantify which PCBs are present but also determine PCB concentration.
In research already conducted at Eltron, Raman spectroscopy and multivariate analysis were combined to create a rapid, in situ sensor capable of simultaneously detecting PCB concentration and composition within transformer oil. Regression models were prepared that could detect PCB concentrations as low as 5 ppm and classification models were prepared that could predict the type of Aroclor present in transformer oil. During current research, sensor sensitivity will be improved by testing all major transformer oil types and accounting for appropriate interferences. Surface Enhanced Raman Spectroscopy will be used to lower the sensor detection limit. Finally, a prototype instrument including user friendly software will be prepared for field testing.
The final product of this project will be a real-time sensor that is cost-effective, portable, user friendly, and most importantly will eliminate the hazardous removal and transportation of contaminated transformer oil for PCB analysis. The expected cost of the instrument will be the same as current GC costs ($30K); however, the per-sample testing cost will be significantly less than GC methods. A hand-held sensor, Eltron’s instrument will be very useful to electric utilities and waste disposal companies for rapid field analysis. Eltron has obtained in kind support from both electric utilities (Sacramento Municipal Utility District) and hand-held Raman instrument manufacturers (Raman Systems Inc). The global market for this type of instrument is expected to be US$119 M by 2009.