电晕放电下全氟异丁腈(C_4F_7N)与空气混合气体的分解产物规律及其形成原因分析
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摘要
3M公司开发的全氟异丁腈C_4F_7N(Novec 4710)在电气强度和环保方面表现良好,具有替代SF6气体的潜能。然而,作为衡量是否具有可替代性的根本条件之一,C_4F_7N分解特性的相关研究还比较少。为探究C_4F_7N的分解特性,采用C_4F_7N与空气混合的方式,实施了一系列工频交流电晕放电实验,建立了C_4F_7N分解气体的气相色谱-质谱(GC/MS)检测方法,定性和定量分析了C_4F_7N体积分数和施加电压影响下的C_4F_7N/空气的分解特性。实验结果表明,C_4F_7N/空气混合气体电晕放电分解产物主要是CO、CO_2、CF_4、C_2F_6、C_2F_4、C_3F_8、C_3F_6、CF_3CF=CFCF_3、CF_3C≡CCF_3、CF_3CN和CHF_3等,饱和卤代烃类气体的体积分数与施加电压和C_4F_7N体积分数均呈正相关。最后,基于密度泛函理论(DFT),初步解释了C_4F_7N关键分解组分形成原因,即,CF_4、C_2F_6、C_2F_4、C_3F_8和CF_3CN主要是由CF_3、CF_2、F、(CF_3)_2CF和CN自由基直接复合形成,形成过程无需活化能,能自发进行。
SF6 gas has a long life in the atmosphere and a high greenhouse effect. It is imperative to reduce or eliminate the use of SF6 gas. The environment-friendly dielectric C_4F_7N(Novec 4710) developed by 3 M company performs well in electrical strength and environmental protection, which has the potential to replace SF6 gas. There are few studies on the decomposition characteristics of C_4F_7N mixed gas at home and abroad. Therefore, we conducted a series of AC corona discharge experiments, and qualitatively and quantitively analyzed the gas decomposition by-products of C_4F_7N/air by gas chromatography-mass spectrometry(GC/MS). Meanwhile, the influencing factors on the formation of decomposition by-products are discussed, such as mixing ratio and applied voltage. The results show that the major decomposition by-products are CO, CO_2, CF4, C2 F6, C2 F4, C3 F8, C3 F6, CF3 CF=CFCF3, CF3 C≡CCF3, CF3 CN and CHF3, and the content of saturated perfluorocarbon compounds is positively correlated with the applied voltage and C_4F_7N volume fraction. Finally, the formation of the key decomposition by-products was analyzed based on the density functional theory(DFT). It is indicated that CF4, C2 F6, C2 F4, C3 F8 and CF3 CN are mainly formed by direct recombination of CF3, CF2, F,(CF3)2 CF and CN radicals. The formation process requires no activation energy and can be spontaneously generated.
SF6 gas has a long life in the atmosphere and a high greenhouse effect. It is imperative to reduce or eliminate the use of SF6 gas. The environment-friendly dielectric C_4F_7N(Novec 4710) developed by 3 M company performs well in electrical strength and environmental protection, which has the potential to replace SF6 gas. There are few studies on the decomposition characteristics of C_4F_7N mixed gas at home and abroad. Therefore, we conducted a series of AC corona discharge experiments, and qualitatively and quantitively analyzed the gas decomposition by-products of C_4F_7N/air by gas chromatography-mass spectrometry(GC/MS). Meanwhile, the influencing factors on the formation of decomposition by-products are discussed, such as mixing ratio and applied voltage. The results show that the major decomposition by-products are CO, CO_2, CF4, C2 F6, C2 F4, C3 F8, C3 F6, CF3 CF=CFCF3, CF3 C≡CCF3, CF3 CN and CHF3, and the content of saturated perfluorocarbon compounds is positively correlated with the applied voltage and C_4F_7N volume fraction. Finally, the formation of the key decomposition by-products was analyzed based on the density functional theory(DFT). It is indicated that CF4, C2 F6, C2 F4, C3 F8 and CF3 CN are mainly formed by direct recombination of CF3, CF2, F,(CF3)2 CF and CN radicals. The formation process requires no activation energy and can be spontaneously generated.
引文
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[17]李康.c-C4F8混合气体替代SF6气体用于电力设备的应用基础研究[D].北京:中国科学院大学,2012.LI Kang.The application investigation of c-C4F8 gas mixtures substituting for SF6 using in electrical apparatus[D].Beijing,China:China University of Chinese Academy of Sciences,2012.
[18]OWENS J G.Greenhouse gas emission reductions through use of a sustainable alternative to SF6[C]∥Proceedings of the 2016 IEEEElectrical Insulation Conference(EIC).Montréal,Canada:IEEE,2016:535-538.
[19]POHLIN K,KIEFFEL Y,OWENS J.Characteristics of fluoronitrile/CO2 mixture-an alternative to SF6[C]∥CIGRE 2016.Paris,France:CIGRE,2016:D1-204.
[20]KIEFFEL Y,BIQUEZ F,PONCHON P,et al.SF6 alternative development for high voltage switchgears[C]∥CIGRE 2014.Paris,France:CIGRE,2014:D1-305,
[21]ZHANG X X,LI Y,XIAO S,et al.Theoretical study of the decomposition mechanism of environmentally friendly insulating medium C3F7CN in the presence of H2O in a discharge[J].Journal of Physics D:Applied Physics,2017,50(32):325201.
[22]PREVE C,PICCOZ D,MALADEN R.Validation method and comparison of SF6 alternative gases[C]∥CIGRE 2016.Paris,France:CIGRE,2016:D1-205.
[23]中国科学院上海有机化学研究所.化学专业数据库[DB/OL].[2018-05-31].http://www.organchem.csdb.cn/scdb/default.htm?Count=10204673.Shanghai Institute of Organic Chemistry,Chinese Academy of Sciences.Chemistry database[DB/OL].[2018-05-31].http://www.organchem.csdb.cn/scdb/default.htm?Count=10204673.
[24]European Chemicals Agency.C&L inventory database[DB/OL].[2018-05-26].https://echa.europa.eu/information-on-chemicals/cl-inventory-database/-/discli/details/.
[25]STEPHENS P J,DEVLIN F J,CHABALOWSKI C F,et al.Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields[J].The Journal of Physical Chemistry,1994,98(45):11623-11627.
[26]GRIMME S,EHRLICH S,GOERIGK L.Effect of the damping function in dispersion corrected density functional theory[J].Journal of Computational Chemistry,2011,32(7):1456-1465.
[27]GRIMME S,ANTONY J,EHRLICH S,et al.A consistent and accurate ab initio parametrization of density functional dispersion correction(DFT-D)for the 94 elements H-Pu[J].The Journal of Chemical Physics,2010,132(15):154104.
[28]NEESE F.The ORCA program system[J].Wiley Interdisciplinary Reviews Computational Molecular Science,2012,2(1):73-78.
[29]KRISHNAN R,BINKLEY J S,SEEGER R.Self-consistent molecular orbital methods.XX.A basis set for correlated wave functions[J].Journal of Chemical Physics,1980,72(1):650-654.
[30]GOERIGK L,GRIMME S.Efficient and accurate double-hybrid-meta-GGA density functionals-evaluation with the extended GMTKN30 database for general main group thermochemistry,kinetics,and noncovalent interactions[J].Journal of Chemical Theory and Computation,2011,7(2):291-309.
[31]WEIGEND F,AHLRICHS R.Balanced basis sets of split valence,triple zeta valence and quadruple zeta valence quality for H to Rn:design and assessment of accuracy[J].Physical Chemistry Chemical Physics,2005,7(18):3297-3305.
[32]HELLWEG A,H?TTIG C,H?FENER S,et al.Optimized accurate auxiliary basis sets for RI-MP2 and RI-CC2 calculations for the atoms Rb to Rn[J].Theoretical Chemistry Accounts,2007,117(4):587-597.
[33]WEIGEND F.Hartree-fock exchange fitting basis sets for H to Rn[J].Journal of Computational Chemistry,2008,29(2):167-175.
[34]MERRICK J P,MORAN D,RADOM L.An evaluation of harmonic vibrational frequency scale factors[J].The Journal of Physical Chemistry A,2007,111(45):11683-11700.
[35]OKAMOTO Y,TOMONARI M.Ab initio calculations on reactions of CHF3 with its fragments[J].The Journal of Physical Chemistry A,2000,104(12):2729-2733.
[36]刘兴华,何为,杨帆,等.空气放电中电子输运参数的计算与分析[J].高电压技术,2011,37(7):1614-1619.LIU Xinghua,HE Wei,YANG Fan,et al.Simulation and analysis of electron transport parameter in air discharge[J].High Voltage Engineering,2011,37(7):1614-1619.
[2]CHRISTOPHOROU L G,OLTHOFF J K,GREEN D S.Gases for electrical insulation and arc interruption:possible present and future alternatives to pure SF6[R].[S.l.]:NIST Technical Note 1425,1997:1-44.
[3]WOOTON R,KEGELMAN M.Gases superior to SF6 for insulation and interruption[R].[S.l.]:Electric Power Research Insititute(EPRI),1982.
[4]YAMAMOTO O,TAKUMA T,HAMADA S,et al.Applying a gas mixture containing c-C4F8 as an insulation medium[J].IEEE Transactions on Dielectrics and Electrical Insulation,2001,8(6):1075-1081.
[5]KASUYA H,KAWAMURA Y,MIZOGUCHI H,et al.Interruption capability and decomposed gas density of CF3I as a substitute for SF6gas[J].IEEE Transactions on Dielectrics and Electrical Insulation,2010,17(4):1196-1203.
[6]张刘春.SF6替代气体c-C4F8及其混合气体的绝缘性能研究[D].上海:上海交通大学,2007.ZHANG Liuchun.Study on insulation characteristics of c-C4F8 and its gas mixtures substituting SF6[D].Shanghai,China:Shanghai Jiao Tong University,2007.
[7]满林坤,邓云坤,肖登明.c-C4F8/N2与c-C4F8/CO2混合气体的绝缘性能[J].高电压技术,2017,43(3):788-794.MAN Linkun,DENG Yunkun,XIAO Dengming.Insulating properties of c-C4F8/N2 and c-C4F8/CO2 mixtures[J].High Voltage Engineering,2017,43(3):788-794.
[8]焦俊韬,肖登明,赵谡,等.低比例CF3I的CF3I-CO2混合气体在极不均匀电场中的绝缘特性[J].高电压技术,2017,43(3):772-779.JIAO Juntao,XIAO Dengming,ZHAO Su,et al.Insulation characteristics for CF3I-CO2 gas mixtures with low proportion of CF3I in extreme non-uniform electric field[J].High Voltage Engineering.2017,43(3):772-779.
[9]DENG Y K,XIAO D M.The effective ionization coefficients and electron drift velocities in gas mixtures of CF3I with N2 and CO2 obtained from Boltzmann equation analysis[J].Chinese Physics B,2013,22(3):352-357.
[10]LI X W,ZHAO H,JIA S L,et al.Prediction of the dielectric strength for c-C4F8 mixtures with CF4,CO2,N2,O2 and air by Boltzmann equation analysis[J].Journal of Physics D:Applied Physics,2014,47(42):425204.
[11]LI X W,ZHAO H,WU J,et al.Analysis of the insulation characteristics of CF3I mixtures with CF4,CO2,N2,O2 and air[J].Journal of Physics D:Applied Physics,2013,46(34):345203.
[12]邢卫军,张国强,李康,等.C4F8/N2混合气体局部放电特性实验研究[J].中国电机工程学报,2011,31(7):119-124.XING Weijun,ZHANG Guoqiang,LI Kang,et al.Experimental study of partial discharge characteristics of C4F8/N2 mixtures[J].Proceedings of the CSEE,2011,31(7):119-124.
[13]王璁,周福文,屠幼萍,等.直流电压下CF3I/N2混合气体的放电副产物[J].中国电机工程学报,2017,37(4):1268-1274.WANG Cong,ZHOU Fuwen,TU Youping,et al.By-products of CF3I/N2 gas mixtures under DC voltage discharge[J].Proceedings of the CSEE,2017,37(4):1268-1274.
[14]TU Y P,LUO Y,WANG C,et al.Breakdown characteristics of CF3Iand CF3I/N2 gas mixtures in uniform field[C]//Proceedings of the IEEE 11th International Conference on the Properties and Applications of Dielectric Materials,2015.Sydney,Australia:[s.n.],2015:520-523.
[15]ZHANG X X,XIAO S,HAN Y F,et al.Analysis of the feasibility of CF3I/CO2 used in C-GIS by partial discharge inception voltages in positive half cycle and breakdown voltages[J].IEEE Transactions on Dielectrics and Electrical Insulation,2016,22(6):3234-3243.
[16]张晓星,戴琦伟,韩晔飞,等.CF3I在微水条件下的放电分解组分研究[J].高电压技术,2016,42(1):172-178.ZHANG Xiaoxing,DAI Qiwei,HAN Yefei,et al.Investigation towards the influence of trace water on CF3I decomposition components under discharge[J].High Voltage Engineering,2016,42(1):172-178.
[17]李康.c-C4F8混合气体替代SF6气体用于电力设备的应用基础研究[D].北京:中国科学院大学,2012.LI Kang.The application investigation of c-C4F8 gas mixtures substituting for SF6 using in electrical apparatus[D].Beijing,China:China University of Chinese Academy of Sciences,2012.
[18]OWENS J G.Greenhouse gas emission reductions through use of a sustainable alternative to SF6[C]∥Proceedings of the 2016 IEEEElectrical Insulation Conference(EIC).Montréal,Canada:IEEE,2016:535-538.
[19]POHLIN K,KIEFFEL Y,OWENS J.Characteristics of fluoronitrile/CO2 mixture-an alternative to SF6[C]∥CIGRE 2016.Paris,France:CIGRE,2016:D1-204.
[20]KIEFFEL Y,BIQUEZ F,PONCHON P,et al.SF6 alternative development for high voltage switchgears[C]∥CIGRE 2014.Paris,France:CIGRE,2014:D1-305,
[21]ZHANG X X,LI Y,XIAO S,et al.Theoretical study of the decomposition mechanism of environmentally friendly insulating medium C3F7CN in the presence of H2O in a discharge[J].Journal of Physics D:Applied Physics,2017,50(32):325201.
[22]PREVE C,PICCOZ D,MALADEN R.Validation method and comparison of SF6 alternative gases[C]∥CIGRE 2016.Paris,France:CIGRE,2016:D1-205.
[23]中国科学院上海有机化学研究所.化学专业数据库[DB/OL].[2018-05-31].http://www.organchem.csdb.cn/scdb/default.htm?Count=10204673.Shanghai Institute of Organic Chemistry,Chinese Academy of Sciences.Chemistry database[DB/OL].[2018-05-31].http://www.organchem.csdb.cn/scdb/default.htm?Count=10204673.
[24]European Chemicals Agency.C&L inventory database[DB/OL].[2018-05-26].https://echa.europa.eu/information-on-chemicals/cl-inventory-database/-/discli/details/.
[25]STEPHENS P J,DEVLIN F J,CHABALOWSKI C F,et al.Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields[J].The Journal of Physical Chemistry,1994,98(45):11623-11627.
[26]GRIMME S,EHRLICH S,GOERIGK L.Effect of the damping function in dispersion corrected density functional theory[J].Journal of Computational Chemistry,2011,32(7):1456-1465.
[27]GRIMME S,ANTONY J,EHRLICH S,et al.A consistent and accurate ab initio parametrization of density functional dispersion correction(DFT-D)for the 94 elements H-Pu[J].The Journal of Chemical Physics,2010,132(15):154104.
[28]NEESE F.The ORCA program system[J].Wiley Interdisciplinary Reviews Computational Molecular Science,2012,2(1):73-78.
[29]KRISHNAN R,BINKLEY J S,SEEGER R.Self-consistent molecular orbital methods.XX.A basis set for correlated wave functions[J].Journal of Chemical Physics,1980,72(1):650-654.
[30]GOERIGK L,GRIMME S.Efficient and accurate double-hybrid-meta-GGA density functionals-evaluation with the extended GMTKN30 database for general main group thermochemistry,kinetics,and noncovalent interactions[J].Journal of Chemical Theory and Computation,2011,7(2):291-309.
[31]WEIGEND F,AHLRICHS R.Balanced basis sets of split valence,triple zeta valence and quadruple zeta valence quality for H to Rn:design and assessment of accuracy[J].Physical Chemistry Chemical Physics,2005,7(18):3297-3305.
[32]HELLWEG A,H?TTIG C,H?FENER S,et al.Optimized accurate auxiliary basis sets for RI-MP2 and RI-CC2 calculations for the atoms Rb to Rn[J].Theoretical Chemistry Accounts,2007,117(4):587-597.
[33]WEIGEND F.Hartree-fock exchange fitting basis sets for H to Rn[J].Journal of Computational Chemistry,2008,29(2):167-175.
[34]MERRICK J P,MORAN D,RADOM L.An evaluation of harmonic vibrational frequency scale factors[J].The Journal of Physical Chemistry A,2007,111(45):11683-11700.
[35]OKAMOTO Y,TOMONARI M.Ab initio calculations on reactions of CHF3 with its fragments[J].The Journal of Physical Chemistry A,2000,104(12):2729-2733.
[36]刘兴华,何为,杨帆,等.空气放电中电子输运参数的计算与分析[J].高电压技术,2011,37(7):1614-1619.LIU Xinghua,HE Wei,YANG Fan,et al.Simulation and analysis of electron transport parameter in air discharge[J].High Voltage Engineering,2011,37(7):1614-1619.