360°风作用下线条风荷载分配系数特性

线条风荷载的准确计算是输电杆塔设计的关键一步,角度风荷载分配系数的选取是否合理将直接影响到设计指标的合理性。对常规线条风荷载（0.5Φ₁=0.5Φ₂=0）的计算原理进行梳理和分析,得到了0~90°范围内的角度风荷载分配系数。同时,通过对风向角θ和线路转角Φ的剖析,推导了线路前后侧360°风吹时的线条角度风荷载分配系数计算公式,并给出了前后侧挡距不同分配比例（0.5Φ₁=0.5Φ₂,0.5L₁∶0.5L₂=5∶5、4∶6、3∶7）时的线条角度风荷载分配系数,分析了分配系数的特点,并进行了对比研究。研究结果揭示了线条角度风荷载分配系数的特点,可作为输电杆塔抗风设计的一种参考。     

基于CEMS数据的超低排放燃煤机组大气污染物排放特性分析

以54台超低排放燃煤机组为研究对象,对比分析了主要大气污染物(颗粒物、SO₂、NOx)的年排放达标率、年排放浓度、排放性能等排放特征。在对环保设施投运和故障进行调查的基础上,分析了排放超标和故障的原因。结果显示：参与调查的燃煤机组中颗粒物、SO₂、NOx排放年度达标率分别为99.981%、99.962%、99.893%,表明能够稳定实现超低排放;颗粒物、SO₂、NOx排放绩效均值分别为11.11、68.16、140.26 mg/(kW·h),满足且优于国家标准要求;启停时段颗粒物、SO₂、NOx排放超标时长占比分别为54%、64%、57%,说明机组启停过程中颗粒物、SO₂、NOx排放浓度难以控制,消除启停机期间制约环保设施正常投运的影响因素是后续主要研究方向。     

特高压配套外送电源碳排放水平研究

随着国家清洁低碳、安全高效的现代电力工业体系的构建,远距离、大容量配套新能源电力外送已成为转变能源资源配置的一项重要途径.如何评估此类项目CO2排放水平及节能减排效益,已受到各界关注.以陕北某特高压直流输电工程为例,对其配套外送电源的CO2排放水平进行研究.结果表明:该工程实施火电与新能源打捆外送,不仅扩大送端省份的新...     

燃煤电厂WESP颗粒物脱除机制及排放特征研究

从强化荷电和促进细颗粒团聚两方面对湿式电除尘器（WESP）细颗粒强化脱除机制进行了分析。并基于调研和现场实测方式,对国内投运的WESP颗粒物排放特征进行了系统研究。采用ELPI测定WESP进出口粉尘粒径分布,采用滤筒方法测定总尘,采用ELPI、PM-10或DGI测定PM₁₀、PM_2.5浓度,采用冷凝法测定SO₃。对调研及实测数据进行统计分析：ELPI将PM₁₀从0.03~10 μm被分为12等级,WESP对PM₁₀各级粒径均有明显的去除效率,数浓度、质量浓度去除效率均在40%以上,最高可达90%以上;WESP出口颗粒物浓度0.43~12.5 mg/m³,绝大部分在5 mg/m³以下,除尘效率均在70%以上,最高可达90%以上;WESP出口PM_2.5浓度0.35~1.59 mg/m³,大部分数据低于1 mg/m³,且脱除效率大部分在60%以上,最高可达90%以上;WESP出口SO₃浓度0.10~3.21 mg/m³,脱除效率均大于60%,最高可达90%以上。调研某350 MW机组WESP出口连续3个月CEMS数据,颗粒物小时浓度达标率为100%,系统实现了长期稳定运行。     

Composition Optimization and Phase Transformation of Si-Nanocrystal-Doped $hbox{SiO}_{x}$ for Enhancing Luminescence From MOSLED

Near-infrared (NIR) photo- and electroluminescence (PL and EL) of Si nanocrystals buried in Si-rich SiO_x, film, and their correlation with the structural phase transformation and the varied oxygen composition of SiO_x, are investigated. By detuning the N₂O flowing ratio (Y_{N 2 O} = [N₂O/(N₂O + SiH₄)] times 100%) from 93% to 80% during plasma-enhanced chemical vapor deposition growth, the oxygen composition ratio of the Si-rich SiO_x, can be adjusted from 1.64 to 0.88. The grazing incident X-ray diffraction and X-ray photoelectron spectroscopy spectra indicate that the SiO_x, transforms its structural phase from Si + SiO₂ isomer to Si + SiO + SiO₂ isomer. With O/Si ratio >1.24, the SiO_x, matrix becomes SiO₂ isomer, whereas the SiO_x, structure approaches SiO phase at O/Si ratio that is nearly 1.0. The formation of SiO matrix in SiO_x, grown at Y_{N 2 O} below 85% reduces the precipitated Si nanocrystal density from 2.8 times 10¹⁸ to 7 times 10¹⁶ cm^-3, and monotonically attenuates the NIR PL by one order of magnitude. Such a structural phase transformation from SiO₂ to SiO in SiO_x with lower O/Si ratio causes the degradation in EL power conversion efficiency and external quantum efficiency (EQE). Maximum EL power of 0.5 muW and EQE of 0.06% are obtained from MOSLED made on SiO_x, with optimized O/Si ratio of 1.24.     

Investigation of S2F10 production andmitigation in compressed SF6-insulated power systems

The Cooperative Research and Development Agreement (CRADA), established to study the production and mitigation of S₂F₁₀ (disulfur decafluoride), one of a number of toxic by-products formed in electric discharges in the insulating gas SF ₆, is described. The particular concern about S₂F ₁₀ is due to its highly toxic nature, the ceiling limit value being 10 parts per billion (ppb, or 1 part in 10⁸), and the need for development of sensitive detection techniques down to this level. In the presence of an electrical discharge such as an arc, spark, or corona, a portion of the SF₆ decomposes into lower fluorides of sulphur which can react to form a number of chemically active by-products including SOF₂ and SO₂F₂ . During the maintenance or repair of SF₆-insulated equipment, the handling of these gaseous is a matter of concern. Preliminary arc experiment results, reported health-related incidents caused by SF₆ by-products, and ongoing studies are discussed     

Simulation of limiting field behavior in electron swarms inSF6+N2 gas mixtures

Limiting field behavior of the electron swarms in SF₆+N ₂ mixtures is investigated by a Monte Carlo simulation technique. (E/N)_lim values directly obtained from the simulation are given for 5, 10, 20, 40, 60 and 80 SF₆ fractional component in the mixture together with the corresponding electron drift velocities and mean energies. Furthermore, in the E/N range of 243⩽E/N⩽606T_d, effective ionization coefficients and mean energies in SF₆+N₂ mixtures are also evaluated with fractional SF₆ contents of 0, 20, 40, 60, 80 and 100%. The simulation results obtained are compared with the available data in the literature     

Area and volume effects on breakdown strength in liquid nitrogen

We measured dc and ac breakdown voltages in liquid nitrogen (LN ₂) with a sphere-to-plane electrode configuration. Experimental results revealed that the breakdown voltage in LN₂ did not increase monotonously but partially decreased as the sphere diameter increased at a constant gap length. Thus, the existence of the area and the volume effects on the breakdown voltage in LN₂ was verified quantitatively; the breakdown strength decreased when increasing the {SEA}₉₀ (90% stressed electrode area) and the {SLV}₉₀ (90% stressed liquid volume). By changing the experimental conditions, it was verified that both area and volume effects, having a mutual correlation, simultaneously lead to the degradation of the breakdown strength in LN₂. In order to examine the area and the volume effects for the larger {SEA}₉₀ and {SLV}₉₀, we also measured the breakdown voltage with a coaxial cylindrical electrode. It was concluded that the dc and ac breakdown strengths in LN₂ decreased as the {SEA}₉₀ and the {SLV}₉₀ increased varying widely from 10⁰ to 10⁵ mm² and from 10 ^-1 to 10⁵ mm³, respectively     

火电行业大气污染物排放对PM2.5 的贡献及减排对策

“十一五”期间,中国电力装机容量从2005年年底的50 841万kW增长至2010年年底的96 219万kW,其中火电装机从38 413万kW增长至70 663万kW。电煤消费量从2005年的10.63亿t 增长至2010年的15.11亿t。2010年,我国火电行业烟尘排放量为218.4万t,SO₂排放量为984.4万t,NO_x排放量为954.2万t。研究表明：2010年我国PM₁₀排放总量3 797.3万t,PM_2.5排放总量为2 278.4万t。2010年火电行业排放的一次细颗粒物PM_2.5为100.8万t,火电行业排放的SO₂转化为二次细颗粒物PM_2.5为350万t,排放的NO_x转化为二次细颗粒物PM_2.5为265.5万t,排放的SO₃转化为二次细颗粒物PM_2.5为107.3万t,合计占PM_2.5排放总量的36.1%。为减少火电行业PM_2.5排放,建议加强环保设施的运行监管,同时出台经济政策引导企业主动减排,湿法脱硫后加装湿式电除尘器以有效减少PM_2.5的排放。     

SF6电流互感器绝缘缺陷的放电及气体分解特性

选取铝筒均压型和电容屏均压型的500 kV SF₆电流互感器（CT）试品,研究了绝缘子沿面缺陷和复合缺陷下的放电及气体分解特性,并分析了缺陷类型、放电路径长度和采气位置对该特性的影响。发现相位分辨率的脉冲序列（PRPD）谱图是气体分解特性研究的良好辅助手段,改良设计的采气口检测结果更准确。绝缘介质缺陷的典型特征是含C物质（CF₄、CS₂）的生成。绝缘子沿面缺陷下SO₂含量高于SO₂F₂,S₂OF₁₀的含量增长率较低,且放电路径长度会影响典型产物的种类。复合缺陷下SO₂F₂和SO₂的含量增长率较高,S₂OF₁₀的含量增长率相对低。     

Ion mobility spectrometry for on-site sensing of SF6decomposition

Although gas-insulated system (GIS) and substations belong to the most reliable components of electric power networks, failures still occur in their long-term operation. In order to estimate the probability of malfunctions in advance, a system for monitoring the quality of the insulating gas SF₆ was established, which is based on the use of ion mobility spectrometry (IMS). In a set of experiments, partial discharge (PD) was generated inside a test GIS. The SF₆ was periodically analyzed using IMS. The results of this analysis is presented and the influence of impurities remaining inside the compartment is discussed. The analysis of gas contained in a circuit breaker in a hydroelectric power plant before and after operation is described as well as the structure of a system for automatic on-site sensing of SF₆ decomposition     

Postdeposition-Anneal Effect on Negative Bias Temperature Instability in HfSiON Gate Stacks

The effect of postdeposition anneals in various ambients on negative bias temperature instability (NBTI) in metal-organic chemical-vapor-deposited HfSiO(N) stacks is investigated. The nitrided stacks, either by anneal or decoupled plasma nitridation (DPN) followed by a postnitridation anneal in O₂ or N₂ (DPN + O₂ and DPN + N₂ ), are more degraded by NBTI than the nonnitrided ones (O₂, N₂ anneal, and as deposited stacks). Moreover, none of the nitrided stacks reaches the 10-year NBTI lifetime, while the lifetime for the nonnitrided ones is larger than 10 years. Nitrogen profiles measured by X-ray photoelectrons spectroscopy and charge-pumping-current data show a relation between nitrogen location and positively charged defects in the gate stack. The additional NBT degradation in nitrided stacks is due to filling or generation of nitrogen-related defects by holes that are injected from the channel.     

基于中试平台的低低温电除尘器深度试验研究

基于50 000 m³/h实际烟气中试试验系统,采用常规采样枪+玻纤滤筒和一体化采样头+石英滤膜测定总尘,采用ELPI测定PM_2.5,采用自制的控制冷凝+异丙醇吸收系统测定SO₃,采用BDL型飞灰工况比电阻测试仪测定飞灰工况比电阻。试验结果表明,130℃、90℃、80℃时电除尘器出口烟尘浓度分别为11.7mg/m³、9.7 mg/m³、5.4 mg/m³,PM_2.5浓度分别为0.8 mg/m³、0.4 mg/m³、0.2 mg/m³,总尘及PM_2.5减排效果显著;电除尘器出口SO₃浓度分别为1.25 mg/m³、0.10 mg/m³、0.14 mg/m³,对应低低温电除尘系统的SO₃脱除效率分别为22.84%、96.15%、96.61%,低低温电除尘系统可脱除烟气中绝大部分SO₃;电除尘器入口飞灰工况比电阻分别为3.02×10¹³ Ω·cm、6.15×10¹² Ω·cm、5.24×10¹¹ Ω·cm。     

Spectral analysis of the light emitted by streamers in hydrocarbonliquids

This paper presents the results of a spectroscopic study from 200 to 850 nm of the light emitted by streamers initiated in cyclohexane and n-pentane under step voltage in point-plane geometry. Experimental spectra of the light emitted by bush-like and filamentary streamers are composed of the H_α-Balmer line, the C₂ Swan band system and a background continuum. The diagnostic method we used for evaluating rotational and vibrational temperatures of excited C₂ in streamers was first tested on high-pressure corona discharges in nitrogen. For streamers in cyclohexane and n-pentane, it was impossible to determine the rotational temperature of C₂ and consequently the effective temperature of molecules in the streamer. Moreover, we found that vibrational populations of excited C₂ do not follow Boltzmann statistics. This indicates that excitation processes are due to chemical reactions. Electron densities deduced of the Stark broadening of H_α are in the range 4×10 ¹⁶ to 7×10¹⁶ cm^-3 for filamentary streamers and 2 to 6×10¹⁷ cm^-3 during the breakdown phase. For slow bush-like streamers, the electron density is not measurable     

中国煤电生命周期二氧化碳和大气污染物排放相互影响建模分析

煤电在中国电力供应结构中占据主导地位,其环境影响是研究热点之一。建立中国煤电生命周期二氧化碳和大气污染物排放分析模型,基于文献调研构建参数数据库,测算中国煤电的单位发电量排放。结果表明,近年来中国煤电生命周期单位发电量的CO₂、SO₂、NO_x和PM_2.5排放分别为838.6 g/（kW·h）、0.34 g/（kW·h）、0.32 g/（kW·h）和0.08 g/（kW·h）。其中煤电单位发电量大气污染物排放,比实施超低排放改造前,下降幅度超过90%。研究发现,增大单机机组规模和进行超低排放改造能够有效降低煤电发电过程的大气污染物排放,采用煤电燃烧后碳捕集和存储(carbon capture and storage, CCS)处理技术能够使煤电CO₂排放下降到144 g/（kW·h）,助力碳中和目标实现。如果不采用更加严格的大气污染物排放标准和处理方式,CCS技术可能会使煤电大气污染物排放强度上升30%~40%,这与碳捕集过程使用的技术有关。     

Spark decomposition of SF6: chemical and biologicalstudies

Because electric arcs, sparks or corona can decompose SF₆ insulators into byproducts having chemical properties different from SF₆, environmental concerns arise regarding inadvertent human exposures to electrically decomposed SF₆. Biological assays using mammalian cell culture systems have revealed that SF₆ , spark-decomposed under specific experimental conditions, can produce cell death. Chemical analysis of spark-decomposed SF₆ has identified the major decomposition pathways and byproducts. Biological testing of individual byproduct mixtures has indicated that these major decomposition products may not account for the majority of the cell-killing effects seen in the assays. Further experiments have suggested that S₂F₁₀ may be produced and accumulate under the specific decomposition conditions and that this compound may be a major contributor to the observed cell lethality. It is concluded that testing of samples from commercial facilities and assays of decomposed gas after ameliorative treatments would both be appropriate investigations     

Optical and Photoluminescence Properties of Erbium-Doped Chalcogenide Glasses (GeGaS:Er)

We have examined the optical and photoluminescence (PL) properties of Er³⁺-doped GeGaS glasses of near-stoichiometric composition Ge₂₈Ga_6.2S_65.3:Er_0.5. We have also used powdered samples of various mean sizes (L) to examine the dependence of the 1.54 -mum PL emission spectrum and the PL decay time on the average sample size. Optical absorption spectra of Er³⁺ ions arising from transitions between different energy manifolds, such as 4 I_{15 /2} -⁴ I_13/2,⁴ I_{15 /2} -⁴ I_{11 /2} , etc., have been used to extract Omega₂, Omega₄, and Omega₆ values using the Judd-Ofelt analysis and a Judd-Ofelt radiative lifetime T_JO = 2.6 ms for the ⁴ I_{13 / 2} -⁴ I_{15 / 2} transition. The PL emission spectra and the decay time have been found to depend on the mean sample size. The spectra are broader and the decay times are longer for larger sample sizes, due to photon trapping occurring in the sample. The extrapolated decay time to zero particle size yields a decay time that matches the Judd-Ofelt radiative lifetime almost perfectly, and confirms the argument that the true PL lifetime needs to be measured in fine powders to avoid reabsorption effects. We have estimated the maximum emission cross section as 15.5 X 10^-21 cm².     

Removal of NF3 from semiconductor-process flue gases bytandem packed-bed plasma and adsorbent hybrid systems

A tandem hybrid gas cleanup system, consisting of a BaTiO₃ packed-bed plasma reactor and a CaCO₃ adsorbent filter, was used to study the removal of NF₃ from semiconductor-process flue gases. Plasma-chemical kinetics of N₂ -NF₃-O₂-H₂ gas mixtures suggested byproducts observed in the experiments. The laboratory-scale system showed NF₃ removal at atmospheric pressure. Typically, 100% NF₃ abatement was achieved with an inlet concentration of 5000 ppm and a gas residence time in the reactor less than 10 s     

Creation of sparse boundary element matrices for 2-D andaxi-symmetric electrostatics problems using the bi-orthogonal Haarwavelet

In our previous paper we described the creation of sparse boundary element matrices that arise from Laplace's equation with mixed boundary conditions using an orthogonal wavelet basis. In this paper we examine the properties of wavelet expansions, and propose a way to construct even sparser matrices than the ones we obtained using the conventional Haar wavelet. We observe that the number of `vanishing moments' of a wavelet qualitatively determines the density of BEM matrices. Then we introduce a way of constructing a wavelet that has more vanishing moments than Haar's wavelet, but still retains a form that is very simple to implement. The time to solution employing the new wavelet is comparable to the Haar wavelet; both are faster than algorithms that rely on a conventional piecewise constant basis. However the quality of the solution is much better, for a given sparsity, the L₂ error of the source distribution is as much as an order of magnitude lower with the new bi-orthogonal wavelet     

Sulphur hexafluoride-A complex dielectric

Some of the factors that must be taken into account in designing with SF₆ are discussed. These factors include the effect of field inhomogeneities on the electrode which reduce the dielectric strength in SF₆ and the effect of SF₆ decomposition byproducts on the materials used in SF₆-insulated systems. Homogeneous and inhomogeneous field breakdown are discussed, and typical causes of failure in SF₆-insulated systems are examined. Many oversimplifications are used in the discussion, mainly to avoid having to define precisely the circumstances to which the assertions apply. In general, the system under consideration has been designed for a 30-year life, as is typical for a utility apparatus