As the most ideal alternative gas for SF6 at present, i-C4F7N has attracted the attention of many scientists. The study of the breakdown characteristics of i-C4F7N gas mixtures is of great significance for the development and engineering application of eco-friendly electrical equipment. In this paper, we investigated the breakdown characteristics of i-C4F7N/CO2 gas mixtures under different mixing ratios, pressures and electric fields. Further, we analyzed the influence of the nonuniformity of the electric field and AC power source on breakdown voltage In addition, we propose a three-component insulation gas solution, which includes i-C4F7N, CO2 and O2(1-9%).

Global warming is a severe test facing the international community. As a serious greenhouse gas, the emission of SF6 has been restricted. In recent years, more and more experts and scholars have turned their attention to alternative gases of SF6. C5F10O(GWP<1) as an alternative gas is investigated by scientists due to good dielectric properties and weak greenhouse effect in recent years. In the first part, this review introduced the background of SF6 and C5F10O. In the second part, we elaborated on four synthetic methods of C5F10O. Trifluoroacetyl fluoride is the key raw material, CsF is an important catalyst. In the third part, the review presented the dielectric and arc interruption properities of C5F10O and its mixtures. The addition of O2 can increased the breakdown voltage of gas mixture. Finally, the decomposition mechanism and products of C5F10O，C5F10O/CO2 or C5F10O/N2/O2 gas mixtures are reviewed.

As global climate change intensifies, higher requirements are imposed on the insulation and environmental performance of eco-friendly gases for electrical insulation. Although SF6 gas has excellent insulating properties and arc-quenching capabilities, it has been classified as one of the greenhouse gases in the Kyoto protocol. At present, SF 6 emissions have been restricted. Many researchers and academic institutions are committed to the research and development of SF 6 replacement gas in order to achieve the development of green energy. The GWP of heptafluoroisobutyronitrile($i-C_{4}F_{7}N$) is only 2210, which is far lower than that of SF 6 . The gas $i-C_{4}F_{7}N$ as a potential and alternative gas for SF 6 has attracted academics’ attention. Recently, GE has built a 420 kV $i-C_{4}F_{7}N/CO_{2}$ GIL. In the first part, this review briefly introduced the background of insulating gases and the discovery of $i-C_{4}F_{7}N$. Then it broadly covers the new progress on the preparation of $i-C_{4}F_{7}N$ in the second part. Methylperfluoroisobutyrate, perfluoroisobutyryl acid, tetrafluoroethylene, hexafluoropro-pylene and perfluoro(4-methylpent-2-ene) can be used as the initial starting material to synthesize $i-C_{4}F_{7}N$. In the third part, the review presented the new research progresses on dielectric properties of $i-C_{4}F_{7}N$ and $i-C_{4}F_{7}N/CO_{2}$ gas mixture. The pure $i-C_{4}F_{7}N$ shows a dielectric strength which is approximately twice that of SF 6 . In addition, experimental study indicates that the dielectric strength of the $i-C_{4}F_{7}N$ gas mixture with 18–20% $i-C_{4}F_{7}N$ can be achieved similar to that of pure SF 6 . Further, it reviews the research progress on the insulation properties of the $i-C_{4}F_{7}N$ gas mixture over the past 3 years. They have a great influence on reducing greenhouse gas emissions from the electrical industry and the application of $i-C_{4}F_{7}N$ in industry. In the last part, the research progress on dissociative ionization dynamics of dielectric gas $i-C_{4}F_{7}N$ was described. Furthermore, the decomposition products and mechanism of the environmentally friendly insulating gas $i-C_{4}F_{7}N$, $i-C_{4}F_{7}N/CO_{2}$ or $i-C_{4}F_{7}N/N_{2}$ gas mixture under different experimental conditions (temperature or discharge) are reviewed. Besides, the achievements on the main decomposition pathways of $i-C_{4}F_{7}N$ and the enthalpy of each path at different temperatures were described.

电网企业的环保废弃物处理处置是新形势下电网环保工作的一个新的关注热点.结合国内环保废弃物处置现状,结合电网企业特点,对电网企业废油、退役蓄电池、废水、SF6气体等不同类型废弃物处理、处置及回用技术路线、策略进行了综合分析,提出了不同类型环保废弃物处置策略建议.

纤维素纳米颗粒是一种容易制备,且价格低廉并具有一定可再生性的吸附材料,被广泛运用到有机污染物的去除等方面.通过实验制备高纯度纤维素纳米材料,并将其与3种不同的脂肪酸进行反应,得到改性后的纤维素纳米材料.结果表明:改性后材料的碳元素含量大幅提升,长碳链被成功移植到纤维素纳米材料的表面;通过FTIR,XPS和XRD光谱分析表明,所生成的化合物与理论分析结果相符.该改性纤维素纳米材料的研究成果将为变电站及火电厂提供更先进的污水处理材料.

Through the analysis of soil erosion characteristics of power transmission construction project during construction in Xi'an plains as well as projects the relation between project constniction and soil & water conservation,the paper proposes several soil & water conservation measures to reduce the soil erosion in power grid construction and protect the ecological environment,and also provides a scientific basis and foundation for building the database of the soil erosion assessing.

Through the mechanism analysis of coal storage yard dust emission in thermal power plant,this paper discusses the principle of wind proofing and dust suppression technology and the structure of the wind proofing and dust suppression device, analyzes several main parameters affecting wind deceleration and dust suppression,such as the opening ratio of wind shield,the height of shelter net,covered distance and so on.From the point of view of environmental impact,the paper calculates a dust emission rate and the ground concentration of the coal -dust,analyzes the energy saving effect of the wind proofing and dust suppression technology,which verifies that the technology is suitable for coal-dust control for thermal power plant in northwest China.

Environmental risk identification during environmental impact assessment of power transmission project is an important assurance to the progress.GIS(Geographic Information System,GIS) application in environmental impact assessment of power transmission project is introduced here as a new technique to indentifying the environmental sensitive area.A technique development and its structure of environmental sensitive area GIS are also represented.The steps of environmental sensitive area identification using the technology is illustrated,application results in environmental impact assessment are summarized.It is showed that environmental sensitive area GIS can be used as a new method and accessory tool to indentify environmental sensitive areas,which has wide perspective and practicability.

GGH(Gas Gas Heater) is an important part of wet flue gas desulfurization system in coal-fired unit.Through formula derivation and field test research,the paper proposes thermal performance test method,contents and cautions for GGH in the wet flue gas desulfurization system,with an emphasis on introducing the essentials of leakage rate test,and hope to provide a reference for the thermal performance test.

For further improving the pertinence,practicability and maneuverability of emergency plan,perfecting the compilation of environmental pollution sudden event plan,improving prevention coping ability of sudden environmental pollution events,analysis discussion are conducted on risk identification,emergency preparation,emergency response and treatment of sudden event emergency plan compilation.