• Title/Summary/Keyword: SF6

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Conceptual Design and Operation Results for SF6 Decomposition and Pollution Control System (SF6 분해 및 무해화 시스템의 개념 설계 및 운영 결과)

  • Joongwon, Lee;Miyeong, Kim;Jiho, Ahn;Younghwan, Byun
    • KEPCO Journal on Electric Power and Energy
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    • v.8 no.2
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    • pp.111-118
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    • 2022
  • SF6 is used as an insulating gas because of its excellent electrical insulation properties, non-toxicity, and non-inflammability. On the other hand, the global warming potential of SF6 is 23,900 times higher than that of CO2. The Korea electric power cooperation (KEPCO) is responsible for 80% of the domestic SF6 usage, and approximately 6,000 tons are currently charged in electrical and power facilities. KEPCO will gradually replace the insulating gas with SF6-free gas from 2023. SF6 decomposition facilities are required because more than 60 tons of SF6 will need to be disposed of annually from existing equipment. This study developed a novel decomposition and pollution control system that can process 60 tons of SF6 per year. This facility can decompose more than 97.7% of SF6, with the emissions of hazardous and toxic materials below the legal limit.

Evaluation of a Prototype SF6 Purification System for Commercialization

  • Seo, Hai-Kyung;Lee, Jeong Eun;Kim, Kwang Sin;Kim, Kyeongsook
    • KEPCO Journal on Electric Power and Energy
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    • v.6 no.1
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    • pp.53-58
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    • 2020
  • Korea Electric Power Corporation (KEPCO) uses large amount of SF6, one of the potent greenhouse gases, in electric equipment for electrical insulation. KEPCO is developing SF6 recovery and purification technology to minimize the release of SF6 into the environment, to secure certified emission reduction, and to save purchase cost of new SF6 by reusing the refined SF6. A prototype SF6 purification system using cryogenic solidification technology has been built in demonstration scale. To evaluate the feasibility of the commercialization, the system has been operated to purify large amount of used SF6 in a long-term operation and the performance has been economically evaluated. The system was stable enough for commercial operation such that it was able to purify 5.4 tons of used SF6 from power transmission equipment in 2-month operation. Over 99% of the SF6 was recovered from the used gas and the purity of the purified gas was over 99.7 vol%. The operation cost, which is the cost of refrigerant (liquid nitrogen), electricity and labor, per kilogram of purified SF6 was 6,526 KRW. Considering the price of new SF6 in Korea is about 15,000 KRW per kilogram this year, about 56% of the purchase cost can be saved.

Improved sulfur hexafluoride(SF6) gas analysis method for quality management of cryogenic refinement system (극저온 정제시스템의 품질관리를 위한 SF6 가스 분석방법 개선)

  • Lee, Jeong Eun;Cho, Min-ho;Lee, Won Seok
    • KEPCO Journal on Electric Power and Energy
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    • v.8 no.1
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    • pp.37-41
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    • 2022
  • Because sulfur hexafluoride(SF6) is classified as one of the six major greenhouse gases, SF6 handling in power plant such as recovery, purification, and reuse is considered to be important. KEPCO has focused to develop the advanced recovery and purification technology of SF6 reuse. SF6 analysis includes the on-site analyses and on-line analyzer; i.e., (1) on-site analysis has an error rate of ±0.5% and (2) on-line analysis has an error rate of ±0.1%, which is possible to adjust operating conditions and to make the work more conveniently by analyzing SF6 concentration before and after purification step. This paper presents an online analysis method in the SF6 purification and reuse system. In addition, the analysis results and quality guarantees for each section of the analysis system were presented.

Capacitively Coupled SF6, SF6/O2, SF6/CH4 Plasma Etching of Acrylic at Low Vacuum Pressure (저진공 축전결합형 SF6, SF6/O2, SF6/CH4 플라즈마를 이용한 아크릴의 반응성 건식 식각)

  • Park, Yeon-Hyun;Joo, Young-Woo;Kim, Jae-Kwon;Noh, Ho-Seob;Lee, Je-Won
    • Korean Journal of Materials Research
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    • v.19 no.2
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    • pp.68-72
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    • 2009
  • This study investigated dry etching of acrylic in capacitively coupled $SF_6$, $SF_6/O_2$ and $SF_6/CH_4$ plasma under a low vacuum pressure. The process pressure was 100 mTorr and the total gas flow rate was fixed at 10 sccm. The process variables were the RIE chuck power and the plasma gas composition. The RIE chuck power varied in the range of $25{\sim}150\;W$. $SF_6/O_2$ plasma produced higher etch rates of acrylic than pure $SF_6$ and $O_2$ at a fixed total flow rate. 5 sccm $SF_6$/5 sccm $O_2$ provided $0.11{\mu}m$/min and $1.16{\mu}m$/min at 25W and 150W RIE of chuck power, respectively. The results were nearly 2.9 times higher compared to those at pure $SF_6$ plasma etching. Additionally, mixed plasma of $SF_6/CH_4$ reduced the etch rate of acrylic. 5 sccm $SF_6$/5 sccm $CH_4$ plasma resulted in $0.02{\mu}m$/min and $0.07{\mu}m$/min at 25W and 150W RIE of chuck power. The etch selectivity of acrylic to photoresist was higher in $SF_6/O_2$ plasma than in pure $SF_6$ or $SF_6/CH_4$ plasma. The maximum RMS roughness (7.6 nm) of an etched acrylic surface was found to be 50% $O_2$ in $SF_6/O_2$ plasma. Besides the process regime, the RMS roughness of acrylic was approximately $3{\sim}4\;nm$ at different percentages of $O_2$ with a chuck power of 100W RIE in $SF_6/O_2$ plasma etching.

Effect of Al2O3 Addition on SF6 Decomposition by Microwave Irradiation (마이크로파 조사에 의한 SF6 분해시 Al2O3 첨가의 영향)

  • Choi, Sung-Woo
    • Journal of Environmental Science International
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    • v.22 no.1
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    • pp.83-89
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    • 2013
  • Silicon carbide with aluminium oxide was used to remove the sulphur hexafluoride ($SF_6$) gas using microwave irradiation. The destruction and removal efficiencies (DREs) of $SF_6$ were studies as a function of various decomposition temperatures and microwave powers. The decomposition of $SF_6$ gas was analyzed using GC-TCD. XRD (X-ray powder diffraction) and XRF (X-ray Fluorescence Spectrometer) were used to characterize the properties of aluminum oxide. DREs of $SF_6$ were increased as the microwave powers were increased. Additive aluminium oxide on SiC increased the removal efficiencies and decreased the decomposition temperature. The XRD results show that the ${\gamma}-Al_2O_3$ was transformed to ${\alpha}-Al_2O_3$ during $SF_6$ decomposition by microwave irradiation. It was found that the best material to control $SF_6$ was SiC with $Al_2O_3$ 30 wt% in consideration of microwave energy consumption and $SF_6$ decomposition rate.

Controlling the Diameter Size of Carbon Nanofilaments by the Cyclic on/off Modulation of C2H2/H2/SF6 Flow in a Thermal Chemical Vapor Deposition System (C2H2/H2/SF6 기체들의 싸이클릭 유량 변조를 통한 탄소 나노 필라멘트 직경크기 조절)

  • Kim, Kwang-Duk;Kim, Sung-Hoon
    • Journal of the Korean Vacuum Society
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    • v.18 no.6
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    • pp.481-487
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    • 2009
  • To control the diameter size of the carbon nanofilaments (CNFs), SF6 was incorporated in the source gases ($C_2H_2/H_2$) during the initial deposition stage. The source gases and $SF_6$ were manipulated as the cyclic on/off modulation of $C_2H_2/H_2/SF_6$ flow in a thermal chemical vapor deposition system. The characteristics of the CNFs formation on the substrate were investigated according to the different cyclic modulation processes and the substrate temperatures. By $SF_6\;+\;H_2$ flow injection during the cycling etching interval time, the diameter size of CNFs was extremely decreased. The cause for the decrease in the diameter size of the individual CNFs by the cyclic on/off modulation process of $C_2H_2/H_2/SF_6$ flow was discussed in association with the slightly enhanced etching ability by the incorporation of $SF_6$.

Study on SF6/O2 Plasmas for Copper Surface Characteristics (SF6/O2 플라즈마를 이용한 구리 표면 처리 후 표면 Corrosion 특성 연구)

  • Im, No-Min;Lee, Jun-Myeong;Lee, Jae-Min;Lee, Byeong-Jun;Gwon, Gwang-Ho
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2015.11a
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    • pp.333-333
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    • 2015
  • 본 연구에서는 디스플레이 패널 식각에 있어서 전극인 구리 박막 표면에 $SF_6/O_2$ 플라즈마 사용 시 발생되는 Corrosion 현상을 분석하기 위해 $SF_6/O_2$ 가스의 조성비를 변화하며 실험을 진행하였다. 유도결합 $SF_6/O_2$ 플라즈마를 이중 랭뮤어 탐침과 광 분광법을 이용한 플라즈마 진단을 통해 $SF_6/O_2$의 조성비의 변화에 따른 플라즈마 상태를 분석하고, $SF_6/O_2$ 플라즈마 조성비를 변화시켜 구리 박막의 표면을 처리한 후 발생되는 Corrosion과 Corrosion이 구리에 미치는 영향을 조사하기 위해 XPS, SEM, 4 point probe 등을 이용하였다.

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Thermal Recovery Characteristics of a CO2 Mixture Gas Circuit Breaker

  • Oh, Yeon-Ho;Song, Ki-Dong;Lee, Hae-June;Hahn, Sung-Chin
    • Journal of Electrical Engineering and Technology
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    • v.11 no.4
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    • pp.969-973
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    • 2016
  • Interruption tests were conducted using the same circuit breaker for an initial pressure of SF6 0.5 MPa (gauge pressure) and CO2 mixture 1.0 MPa, 0.8 MPa, and 0.6 MPa. The pressure-rises in the compression and thermal expansion chambers were measured for verifying the computational results using a simplified synthetic test facility. Further, the possibility of the CO2 mixture substituting SF6 gas was confirmed. Moreover, in view of the thermal recovery capability, it has also been confirmed that the pressure of the CO2 mixture can be reduced almost to the same value as that of the SF6 gas by optimizing the design parameters of the interrupter.

Experimence Study of Trace Water and Oxygen Impact on SF6 Decomposition Characteristics Under Partial Discharge

  • Zeng, Fuping;Tang, Ju;Xie, Yanbin;Zhou, Qian;Zhang, Chaohai
    • Journal of Electrical Engineering and Technology
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    • v.10 no.4
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    • pp.1786-1795
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    • 2015
  • It is common practice to identify the insulation faults of GIS through monitor the contents of SF6 decomposed components. Partial discharges (PD) could lead to the decomposition of SF6 dielectric, so new reactions usually occur in the mixture of the newly decomposed components including traces of H2O and O2. The new reactions also cause the decomposed components to differ due to the different amounts of H2O and O2 even under the same strength of PD. Thus, the accuracy of assessing the insulation faults is definitely influenced when using the concentration and corresponding change of decomposed components. In the present research, a needle-plate electrode was employed to simulate the PD event of a metal protrusion insulation fault for two main characteristic components SO2F2 and SOF2, and to carry out influence analysis of trace H2O and O2 on the characteristic components. The research shows that trace H2O has the capability of catching an F atom, which inhibits low-sulfide SFx from recombining into high-sulfide SF6. Thus, the amount of SOF2 strongly correlates to the amount of trace H2O, whereas the amount of SO2F2 is weakly related to trace H2O. Furthermore, the dilution effect of trace O2 on SOF2 obviously exceeds that of SO2F2.

Partial Discharge Characteristics on Protrusion Defects in SF6-N2 Mixture Gases (SF6-N2 혼합가스 중 돌출 결함의 부분방전 특성)

  • Jo, Hyang-Eun;Wang, Guoming;Kim, Sun-Jae;Park, Kyoung-Soo;Kil, and Gyung-Suk
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.29 no.1
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    • pp.44-49
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    • 2016
  • Studies on a $SF_6$-mixture and -alternative gas has been in progress to reduce the use of $SF_6$ gas as an insulation material of GIS (gas insulated switchgears). In this paper, we dealt with PD (partial discharge) characteristics in pure $SF_6$ and $N_2$, and their mixtures on aspects of insulation design and risk assessment for GIS. A POC (protrusion on conductor) and a POE (protrusion on enclosure) as the major defects were fabricated to simulate PD. We analyzed the DIV (discharge inception voltage), DEV (discharge extinction voltage), pulse magnitude, counts and phase distribution of PD pulse in $SF_6-N_2$ mixtures ($SF_6$ 100%, $SF_6$ 80%-$N_2$ 20%, $SF_6$ 50%-$N_2$ 50%, $SF_6$ 20%-$N_2$ 80%, and $N_2$ 100%) according to the IEC60270. The DIV, DEV as well as magnitude of PD pulse decreased on the POC as increase of $N_2$ ratio. For the POE, the DIV and DEV in $N_2$ ratio below 50% were the same voltages as those in $SF_6$ 100%. In this experiment, $SF_6$ 80%-$N_2$ 20% mixture could be considered with the equivalent insulation performance to a GIS.