Research on plasma arc oxidation efficiency of spark gap switch with graphite electrodes
-
摘要: 氧气是石墨电极气体开关中必不可少的组分，用于氧化石墨电极在高温电弧冲击下形成的石墨蒸汽，防止熄弧后石墨蒸汽凝华成固体粉末给开关带来绝缘危害。为提高石墨蒸汽的氧化比例，研究了背景气体组分和氧气浓度对石墨氧化反应的影响，选取3种气体N2，Ar，He作为背景气体，研究不同气氛电弧的氧化反应特征；在传统的类空气气体（80%的N2＋20%的O2）的基础上，提高氧气浓度至40%和60%，研究氧气浓度对碳质氧化比例的改善作用。基于不同气体组分的热力学参数和输运系数，通过电弧磁流体动力学计算模型得到开关温度特征，将电弧与电极界面的热流强度作为石墨电极质量损失速率的评估依据。实验结果表明，随着氧气浓度的升高，石墨蒸汽的氧化比例逐步提高，但当氧气浓度高于40%时，存在电弧引燃石墨电极的风险。当氧气浓度恒定20%时，以Ar作为背景气体时石墨电极质量损失速率较小，且碳蒸汽在电弧中氧化更加充分。因此，相比于传统的开关气体介质，将背景气体替换为Ar或将氧气浓度提高至约40%均能提升碳氧反应效率，降低开关中的杂质残余量。Abstract: Oxygen is a kind of indispensable component in graphite-electrode spark-gap switch, and it is used to oxidize the graphite vapor formed by the graphite electrode under the impact of high-temperature arcs to prevent the graphite vapor from condensing into solid powder after the arc is extinguished, thus to avoid damage to the switch. To increase the oxidation ratio of the graphite vapor, the influence of background gas composition and oxygen concentration on graphite oxidation reaction is studied in this paper. The effect of dilution gases N2, Ar, and He on characteristics of the oxidation reaction are studied. Meanwhile, on the basis of the traditional air-like gas (80%N2＋20%O2), the carbon oxidation ratio in the case with 40% and 60% oxygen concentration are studied. According to the thermodynamic parameters and transport coefficients of different gases, the arc temperature characteristics are obtained through the magnetohydrodynamic calculation. The thermal energy intensity at the interface between the arc and the electrode is used as the basis for evaluating the mass loss rate of the graphite electrode. Experimental results show that as the oxygen concentration increases, the oxidation ratio of graphite vapor gradually increases. However when the oxygen concentration is higher than 40%, there is a risk of combustion of the graphite electrode. When the oxygen concentration is kept at 20%, the mass-loss rate of the electrode is smaller when Ar is used as the dilution gas, and the carbon vapor is oxidized more fully in the arc. This indicates that compared with the traditional insulation gas, replacing the dilution gas with Ar or increasing the oxygen concentration to around 40% can both improve the carbon-oxygen reaction efficiency and reduce the residual carbon impurities of the graphite-electrode spark-gap switch.
-
Key words:
- spark gap switch /
- pulsed discharge /
- graphite electrode /
- arc temperature /
- carbon-oxygen reaction
-
图 4 不同混合气体的热力学参数及输运系数
Figure 4. Thermodynamic parameters and transport coefficients of different gases
图 5 不同气体中的电弧温度分布随时间的变化趋势
Figure 5. Variation trend of arc temperature distribution in different gases over time
图 6 电弧-电极热传导能量密度
Figure 6. Heat conduction of thermal energy density from arc to electrode
图 7 不同背景气体中放电后碳氧化物气体含量
Figure 7. Content of carbon oxide gas after discharge in different dilution gas
图 8 不同背景气体中碳元素的气态氧化质量与固态残余质量比较
Figure 8. Comparison of the carbon element in solid and gas state after discharge
图 9 不同氧气浓度中放电后碳氧化物气体含量
Figure 9. Carbon oxide content after discharge in different oxygen concentrations
图 10 不同氧气浓度中碳的氧化与残余量
Figure 10. Amount of oxidation and residual carbon in different oxygen concentrations
表 1 不同氧气浓度下开关工作可靠性
Table 1. Reliability of the switch in different oxygen concentrations
transferred charges/C reliability in different oxygen concentrations 20% 40% 60% 4.6 ✔ ✔ ✔ 14.6 ✔ ✔ ✔ 24.5 ✔ ✔ ✔ 35.1 ✔ ✔ occasional combustion（probability＜20%） 45.3 ✔ ✔ frequent combustion（probability＞60%） 
下载: 导出CSV
-
[1] 郭良福, 李黎, 赖贵友, 等. 石墨型高能两电极气体开关[J]. 强激光与粒子束, 2010, 22(12):3034-3038. (Guo Liangfu, Li Li, Lai Guiyou, et al. High power graphite two-electrode spark gap switch[J]. High Power Laser and Particle Beams, 2010, 22(12): 3034-3038 doi: 10.3788/HPLPB20102212.3034 [2] 俞斌, 李黎, 葛亚峰, 等. 大功率能源模块中的石墨电极气体开关系统[J]. 强激光与粒子束, 2014, 26:045021. (Yu Bin, Li Li, Ge Yafeng, et al. Graphite-electrode gas-switching system in high energy module[J]. High Power Laser and Particle Beams, 2014, 26: 045021 doi: 10.11884/HPLPB201426.045021 [3] Takikawa H, Tao Y, Miyano R, et al. Formation and deformation of multiwall carbon nanotubes in arc discharge[J]. Japanese Journal of Applied Physics, 2001, 40(5R): 3414-3418. [4] Arora N, Sharma N N. Arc discharge synthesis of carbon nanotubes: comprehensive review[J]. Diamond and Related Materials, 2014, 50: 135-150. doi: 10.1016/j.diamond.2014.10.001 [5] Dai Hongyu, Li L, Peng Mingyang, et al. Carbon-oxygen reaction efficiency in air gap switch with graphite electrodes under high current pulse discharge[J]. Physics of Plasmas, 2017, 24: 123512. doi: 10.1063/1.5009281 [6] Dai Hongyu, Li L, Wu Haibo, et al. Characteristics of N2/O2 reaction in spark gap switch: the effect of high-current pulsed arc[J]. IEEE Transactions on Dielectrics and Electrical Insulation, 2019, 26(2): 492-500. doi: 10.1109/TDEI.2019.007691 [7] 刘现飞, 唐钊, 刘轩东. 气体介质对多间隙气体开关电晕均压与自击穿特性的影响[J]. 强激光与粒子束, 2020, 32:025012. (Liu Xianfei, Tang Zhao, Liu Xuandong. Effect of gas medium on corona discharge for voltage balance and self-breakdown characteristics in multi-gaps gas switch[J]. High Power Laser and Particle Beams, 2020, 32: 025012 doi: 10.11884/HPLPB202032.0358 [8] Goto K S, Han K H, Pierre G R S. A review of oxidation kinetics of carbon fibre-carbon matrix composites at high temperature[J]. Materials Science and Engineering, 1987, 88: 347. [9] Murphy A B. Thermal plasmas in gas mixtures[J]. Journal of Physics D: Applied Physics, 2001, 34(20): R151-R173. doi: 10.1088/0022-3727/34/20/201 [10] 李兴文, 贾申利, 张博雅. 气体开关电弧物性参数计算及特性仿真研究与应用[J]. 高电压技术, 2020, 46(3):757-771. (Li Xingwen, Jia Shenli, Zhang Boya. Research and application on physical parameters calculation and behavior simulation of gas switching arc[J]. High Voltage Engineering, 2020, 46(3): 757-771 [11] Cai X Y, Dong B L, Lin S B, et al. Heat source characteristics of ternary-gas-shielded tandem narrow-gap GMAW[J]. Materials, 2019, 12: 1397. doi: 10.3390/ma12091397 [12] 李兴文, 吕启深, 田甜, 等. 直流空气电弧作用下触头烧蚀特性[J]. 高电压技术, 2020, 46(6):1970-1977. (Li Xingwen, Lv Qishen, Tian Tian, et al. Contact erosion characteristics under direct current air arc[J]. High Voltage Engineering, 2020, 46(6): 1970-1977 [13] 李美, 王一玮, 李林, 等. 绝缘气体对开关柜内部故障燃弧压力上升的影响[J]. 电气工程学报, 2020, 15(2):11-17. (Li Mei, Wang Yiwei, Li Lin, et al. Influence of insulating gas on pressure rise due to internal fault arcing in switchgear[J]. Journal of Electrical Engineering, 2020, 15(2): 11-17 doi: 10.11985/2020.02.002 [14] Punekar G S, Thejovathi G, Kishor N K. Simulation study of Borda’s profile & parallel plane electrode to assess electric field uniformity[C]//IEEE 8th International Conference on Electromagnetic Interference and Compatibility. 2003: 371-374. [15] 刘毅, 林福昌, 冯希波, 等. 能源模块磁开关工作特性分析[J]. 中国电机工程学报, 2012, 32(36):142-148. (Liu Yi, Lin Fuchang, Feng Xibo, et al. Working characteristics analysis of magnetic switch in energy module[J]. Proceedings of the CSEE, 2012, 32(36): 142-148 [16] Kramida A, Ralchenko Y, Reader J, et al. NIST atomic spectra database (version 5.0)[R]. 2012. [17] Griem H R. High-density corrections in plasma spectroscopy[J]. Physical Review, 1962, 128(3): 997-1003. doi: 10.1103/PhysRev.128.997 [18] Hirschfelder J O, Curtiss C F, Bird R B. Molecular theory of gases and liquids[M]. New York: John Wiley & Sons, Inc., 1954. [19] Devoto R S. Simplified expressions for the transport properties of ionized monatomic gases[J]. The Physics of Fluids, 1967, 10(10): 2105-2112. doi: 10.1063/1.1762005 [20] 曾晗, 林福昌, 蔡礼, 等. 石墨电极烧蚀机理及实验[J]. 电工技术学报, 2013, 28(1):43-49, 86. (Zeng Han, Lin Fuchang, Cai Li, et al. Mechanism and experiment of graphite electrode erosion[J]. Transactions of China Electrotechnical Society, 2013, 28(1): 43-49, 86 doi: 10.3969/j.issn.1000-6753.2013.01.007 [21] 付钰伟, 王小华, 高青青, 等. 火花放电下SF6特征分解产物演化特性研究[J]. 高压电器, 2020, 56(5):13-17, 23. (Fu Yuwei, Wang Xiaohua, Gao Qingqing, et al. Evolution feature of characteristic SF6 decomposition products under spark discharge[J]. High Voltage Apparatus, 2020, 56(5): 13-17, 23 -
点击查看大图
计量
- 文章访问数: 1272
- HTML全文浏览量: 344
- PDF下载量: 41
- 被引次数: 0
