Experimental Study On Degradation Of Sulfur Hexafluoride Gas By Dielectric Barrier Discharge Plasma

Sulfur hexafluoride(SF6)has been widely used in power industry because of its excellent electrical insulation and arc extinguishing performance.With the wide application of SF6 gas insulation equipment,the use of SF6 is increasing.According to statistics,the major source for SF6 emissions is fugitive emissions from the power industry in the field of SF6 applications.In 1997,SF6 was deemed as one of greenhouse gases in terms of the Kyoto Protocol.Therefore,SF6 has become a target greenhouse gases that needs to be curbed for emission.DBD can produce low-temperature plasma with larger volume and higher energy density under the atmospheric pressure.It has a good application prospect in the field of waste gas treatment.In this paper,the DBD plasma technique was used to study the degradation of SF6.The background gas,discharge parameters,additional gases were investigated to study their influences on the process of degradation of SF6 by DBD plasma.Based on the experimental platform of SF6 degradation,the main work and the main conclusions are as follows:1)Under the same input power conditions,four kinds of background gases were used to degrade SF6.The degradation efficiency of Ar as a background gas is the highest,followed by He,air,and N2.Single atom gas is more suitable to be used as background gas.Furthermore,Ar can degrade SF6 more efficiently than He as a background gas.2)Under the same discharge voltage,the discharge intensity and discharge power increases first and then decreases with the increase of the power frequency.The maximum is at the center frequency 8.9 kHz.Further more the degradation rate of SF6 is the highest.With the increases of the input power of the plasma power supply,the discharge power and the power utilization efficiency are increased,and the time needed for the complete degradation of SF6 is less.4)At the same O2 concentration,with the increases of input power,the degradation rate of SF6 is higher,and the time needed for complete degradation is less.With the increases of O2 concentration,the degradation rate of SF6 increases first and then decreases.With the same concentration of O2 and SF6,the degradation effect is best.Adding a certain concentration of H2 will be conducive to the degradation of SF6 under the condition of ensuring the safety of experiment.Under the experimental conditions of this paper,with the increases of H2 concentration,the time needed for complete degradation of SF6 is less and less.The addition of water vapor could promote the degradation of SF6.The degradation rate of SF6 is higher than that without adding water vapor after 2 min.But the corresponding discharge power increases slightly.4)The detection analysis results of degradation products show that,in the absence of any gases,the main products are SO2F2 and SOF2.The formations of SOF4 and SO2 are relatively less,and H2 S is the least.With the addition of O2,the formations of SO2F2 and SOF4 are promoted.While the formations of SOF2 and SO2 are inhibited.Furthermore,SO2F2 and SOF4 are the main degradation products.The addition of H2 or moisture,the H2 S generated is increased,while the formations of SO2F2,SOF4 and SOF2 are inshibited.The research results of this paper will lay a foundation for exploring the mechanism and the industrialized treatment of SF6 degradation by DBD.