Experimental and Simulation Study on Degradation of SF6 by Dielectric Barrier Discharge Plasma

Dielectric barrier discharge (DBD) is widely used in waste gas treatment because of its simple device, low energy consumption and high removal efficiency. In this paper plasma produced by double-layer dielectric reactor was used to degrade SF6 gas. With the frequency of applied voltage unchanged and its amplitude ranging from 7 to 11kV, the concentration of SF6 was detected at different degradation times. The degradation rates were calculated, and then the products were analyzed. The oscilloscope was used to measure discharge waveforms and Q-U Lissajous figures of DBD. Accordingly the discharge power and the amount of transferred charge were calculated. Experimental results show that the degradation rates showed an upward trend with the degradation time increasing under the same applied voltage. At the same degradation time, with the enhancement of applied voltage, the degradation rate also increased. The higher the voltage was, the shorter the time for complete removal of SF6 needed. The main products were SO2F2, SOF4, SOF2 and SO2. The discharge power and the amount of transferred charge increased as the applied voltage increased, which facilitated the degradation of SF6. Besides, the chemical reactions that might occur in degradation process of SF6 by DBD, have been discussed through the simulation computation by the density functional theory (DFT) under room temperature and atmospheric pressure in this paper. Two degradation pathways of SF6, pathways of degradation products, and the reaction heat of each chemical reaction were studied, which provides theoretical basis for the degradation mechanism of SF6 by DBD plasma. © 2017 Chin. Soc. for Elec. Eng.