Change of characteristics of desulfurization and denitrification by combustion flue gas composition and electrode configuration under pulsed corona discharge

Laboratory-scale and parametric experiments of SO₂ and NO_x removal from the simulated combustion gas by pulsed corona discharge have been performed by changing the combustion gas composition and temperature, the electrode configuration of plasma reactor, and the polarity of high-voltage electrode. The following results are obtained: 1) the higher the concentration of H₂O and O₂, the higher the efficiency of desulfurization and denitrification at the same specific input; 2) the pulsed corona discharge with a voltage pulsewidth as short as 200 ns of negative polarity shows the possibility to attain almost 90 percent deSO_x and deNO_x efficiency at the specific discharge input of 20 J/g, which is almost the same as the specific input in the electron-beam process; 3) the deNO_x characteristics show a little temperature dependence in the range of 70 to 130°C, but the deSO_x efficiency increases rapidly in the temperature region below 100°C suggesting the thermochemical dependence of deSO_x reaction; 4) when desulfurization and denitrification proceed, the white dendritic powder deposits on the plasma reactor whose composition is identified to be 49 mol% (NH₄)₂SO₄ and 47 mol% of 2NH₄NO₃ · (NH₄)₂SO₄, and the ratio of SO₂, NO and NH₃ of the deposit is almost equal to that of supplied gas.     

Optimization of corona electrode position in roll-type electrostatic separators

The position of the corona electrode(s) is known to be a key factor of electrostatic separation efficiency, as it influences both the charging conditions of the granular materials on the surface of the roll electrode connected to the ground, and the magnitude of the electric forces exerted on the particles. Response surface methodology was employed for the design of the experiments performed on a laboratory roll-type corona-electrostatic separators, with samples of chopped electric wire wastes typically processed by such techniques. The results of the electrostatic separation tests are discussed in relation to the data obtained from two other experiments, in which corona current and particle charge measurements were performed for various positions of the standard wire-type electrode. The conclusions of this study enabled the formulation of several recommendations for the improvement of the outcome of industrial separation processes (i.e., maximize the weight percentage as well as the purity of the recovered materials).     

Negative corona in air using a point/cup electrode system

Calculations and simulations of potential and charged-particle distributions have been made by various workers for single pulses along the axis of point/plane electrode systems but not for the overall current. The difficult geometry makes this inevitable. In this paper the authors describe measurements of corona currents in air using a high-symmetry `point/cup' electrode system comprising a hemispherical-tipped point which is concentric with a concave hemispherical electrode; and simulations based on a spherically symmetric geometry. The simulations assumed avalanches to originate from the random release of electrons in the inter-electrode gap. The predicted onset voltages and the shape of the experimental curves for corona current vs. Voltage were in good agreement with the experimental results over a range of point-tip radii (0.5 to 3 mm) and pressures (0.02 to 0.10 MPa). Space charge effects were not included in the simulation so it follows that the accumulation of space charge is negligible at the onset voltage in air, although it is likely that it will have an increasing effect as the voltage increases     

Positive corona in air using a point/cup electrode system

The authors have previously published some measurements of negative corona currents in air using a spherically-symmetric point/cup electrode system, and also the related simulations. In this paper the corresponding current/voltage measurements and simulations for positive-point corona, again using the highly symmetric electrode system, are described. Although the corona onset voltages are again predicted with reasonable accuracy for different point radii and air pressures, the currents are very much lower, presumably due to the effect of positive space charge accumulating close to the point electrode (since the simulations assume the absence of space charges). In agreement with this assumption, the streamer pulses are only seen at or just above the onset voltage. Only avalanches occur from about 1 kV above the onset voltage.     

单个绝缘子电晕起始电压的统计特性

为研究单个绝缘子电晕起始电压的特性，通过大量实验，得到了不同湿度，不同等值附盐密度条件下单个绝缘子电晕起始电压，电晕起始概率。实验表明，单个绝缘子电晕起始概率符合统计分布。最后，利用曲线拟合的方法建立了电晕起始电压与相对湿度，等值附盐密度的关系式，该公式对绝缘子的在线检测诊断具有一定的指导意义。     

Charge and voltage characteristics of corona discharges in acoaxial geometry

An engineering model is proposed to evaluate the variation of corona charge and corona current as a function of applied voltage for coaxial geometry (q-v curves). The two main assumptions of the model are the following: for streamer discharges to propagate continuously, the background field must be at, or just above, a critical level; and the streamers maintain a constant voltage gradient in the corona sheath. The model simulations are compared with the experimental q-v curves and a reasonable agreement is obtained between them     

Study on corona characteristics under nonstandard lightning impulses

The q − u curves under damped oscillatory impulses are observed experimentally in a corona cage. An analysis for the experimental results is made with an emphasis on the difference between the q − u curves under damped oscillatory and double exponential impulses. Based on the experimental investigation, a corona model is proposed to calculate the q − u curves under damped oscillatory impulses. Charge, electric field and voltage are related macroscopically in the model. The model parameters can be determined by the measured data under double exponential impulses. The calculated results are compared with the experimental ones and a reasonable agreement is shown between them.     

空气局部放电衍生物气体生成规律的研究

分解气体分析法通过检测故障产生的气体组分诊断设备故障,是检测电力设备故障的重要方法,在一些应用场合具有不可替代的作用。然而目前该方法只在绝缘油、SF6等绝缘介质的场合有应用,对于空气这一最重要的绝缘介质少有应用。本文搭建空气局部放电过程模拟实验平台及气体产物检测系统,研究放电衍生物气体生成规律。分别采用两种检测方式对气体产物进行检测,结果显示O_3、NO、NO_2为空气放电的主要产物;在放电强度较低时,空气放电主要分解产物为O_3,放电强度进一步增大可以检测到氮氧化物NO和NO_2的产生,且臭氧O_3浓度远大于氮氧化物气体浓度;对于封闭空间,随着放电时间增长分解产物浓度增加,但趋向饱和,且随着施加电压增大,气体产物浓度增加;而在相同放电电压下,空气相对湿度变化对气体产物含量有明显影响,O_3、NO_2的浓度在相对湿度为18%时高于相对湿度为25%和44%时的值;而NO的浓度在相对湿度为44%时高于相对湿度为18%和25%时的值,同时差异较小。     

Control and performance of a pulse-density-modulatedseries-resonant inverter for corona discharge processes

This paper presents the control and performance of a pulse-density-modulated (PDM) series-resonant voltage-source inverter developed for corona discharge processes. The PDM inverter produces either a square-wave AC-voltage state or a zero-voltage state at its AC terminals to control the average output voltage under constant DC voltage and operating frequency. This results in a wide range of power control from 0.5% to 100%, even in the corona discharge load with a strong nonlinear characteristic. A 30 kHz 6 kW surface treatment system consisting of a voltage-source PDM inverter, a step-up transformer, and a corona discharge treater shows the establishment of a stable corona discharge in an extremely wide range of power control and, therefore, succeeds in performing both strong and weak surface treatment processes for film     

镉镍电池组第三电极充电信号滞后分析及改进

在镉镍全密封蓄电池内部增加吸氧辅助电极--Ag-Hg电极(下称"第三电极")可(实现)提供地球同步轨道(GEO)卫星镉镍蓄电池组的充电控制信号.分析结果表明.卫星在轨运行时出现第三电极信号电压滞后现象,主要是由于在镉镍电池中所带的第三电极的包覆方式减小甚至阻断了其氧气或电液通道(离子导电通道).为了改善镉镍蓄电池内第三电极的氧气与电液通道,我们改进了第三电极的包覆设计,从而改进了第三电极信号电压滞后现象,使第三电极充电控制方法更可靠地应用于GEO卫星.     

铅晶电极的制备及性能

简述了铅晶电极的制备工艺,研究了铅晶电极的性能.结果表明,与涂膏式电极相比,铅晶电极具有活性物质的晶粒较小、比表面积较大、不容易硫酸盐化和充放电性能较好等优点.     

Computation of high-frequency and time characteristics of corona noise on HV power line

This work presents an algorithm for the computation of frequency and time characteristics of the corona noise in power-line carrier communications. In the frequency domain, the corona noise is represented with a power spectral density and with a Gaussian noise voltage with variable root mean square value in the time domain. Simulations results are compared with measurements on an actual 400-kV power line.     

Basic characteristics of self‐control corona discharge air ionizer

We propose a self‐controlling corona discharge air ionizer for the static neutralization of electronic products in manufacturing processes. This air ionizer automatically generates only the quantity of ions required to neutralize a charged product, without the need for a control system. This is possible as the device generates ions based on the combination of the electric field of the ionizer emitter, to which a threshold voltage is applied, and the electric field of the product. In this study, the required threshold voltage values were determined by assessing the relationship between the neutralization current and the emitter voltage. The neutralization speed and the final product voltage after neutralization obtained from the ionizer operating on AC voltage were investigated using a charged‐plate monitor. The time span required to reduce the charge on a metal plate with a capacitance of 20 pF from 1000 to 100 V was found to be less than 1.0 s, indicating that this device has practical applications. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

微电极材料极化特性研究

为了研究银、铂、玻碳、金、铜电极的极化特性,确定每种材料电极的最佳应用场景,对表面微电极型式进行了详细的理论分析、模型仿真和水槽测量研究,获得了一种表面微电极材料极化阻抗评测方法.结果 表明,铂和玻碳电极测量准确度最优,银电极性能稍次于铂和玻碳电极,金电极仅在50 kHz以上可以适用.综合准确度、灵敏度和可靠度,玻碳电...     

紫外电晕检测仪在电晕放电检测中的应用

首先阐述一种新型紫外电晕检测仪的原理,介绍该仪器目前在国外的应用情况,然后分析该类仪器在系统应用中技术特点和存在的一些问题,最后结合电力系统快速发展的展望了应用的前景。     

不同海拔高度交流电晕电流脉冲特性实验研究

不同海拔高度下交流电晕特性的变化规律是高海拔地区线路设计的基础。文章利用可移动式小电晕笼和高频电流测量系统在20m-4320m范围内的5个海拔高度点进行实验,采集了1mm直径细铜丝在不同施加电压下的电晕电流脉冲、无线电干扰和可听噪声水平数据;通过对实测数据的统计分析及拟合,得到了海拔高度对电晕电流脉冲特性的影响规律,并分析了不同海拔高度下电晕电流同无线电干扰和可听噪声水平的关联关系。研究表明,随着海拔高度增加,交流电晕电流脉冲的幅值增大,幅值概率分布逐渐分散,一个周期内交流电晕电流脉冲的数量增加,脉冲形成时间变得更加均匀;将电晕电流有效值作为中间变量,研究海拔高度对交流线路电晕效应的影响,得到电晕电流有效值与导线施加电压呈线性函数关系,该线性函数的斜率k、截距b均为海拔高度h的三次函数;无线电干扰和可听噪声水平均与电晕电流有效值呈对数增长关系,其中可听噪声与电流有效值的函数关系随海拔高度变化而改变。     

Temperature effect on the performance characteristics of beta raysopen air corona streamer counter

Open air three electrode (point-grid-plane) corona streamer counter with a preamplification gap has been utilized for detecting weakly ionizing beta rays. This is based on the fact that when the primary electrons produced by beta rays are multiplied in the external preamplification gap, they form a trigger electron swarm before entering the counter, produce the same effect as the direct incidence of strongly ionizing particle in the corona counter, and allow the counter to operate efficiently. However, operation of this counter in open air as one of its most attractive features requires a complete analysis of the counter response to the changes of ambient conditions. The effect of temperature on the beta particle corona counter performance is studied. A theoretical model is suggested to calculate the counter operating voltage as well as the beta particles triggered corona pulse characteristics at different temperatures (20°C-50°C). The temperature effects on the counter-energy response is explained. A compensation for the errors due to temperature effects is suggested. All the theoretical findings are confirmed by experiments     

不同电极结构中SF_6/N_2混合气体正向流注电晕放电特性

宏观上假定气体放电过程中产生的正、负离子束和电子束为流体,采用二维流体动力学模型对SF6/N2混合气体正向流注电晕放电过程进行建模,利用通量校正传输法求解连续方程,通过求解耦合的泊松方程处理空间电荷畸变电场对放电的作用,仿真过程中假设带电粒子的输运参数是折算电场的函数,对比分析了平行板电极间隙、同轴电极间隙和棒-板电极间隙三种电极结构中正向流注电晕放电特性。结果表明:流注电晕的形成加强了流注头部与阳极间的场强,减弱了流注尾部与阴极的场强。只有流注头部所在位置的初始场强足够大时放电才能继续发展,否则放电转化为稳定的流注电晕放电。     

普鲁士蓝薄膜电极的制作及充放电研究

以多孔阳极氧化铝作电极活性物质的支撑体,制备了一种新型的普鲁士蓝薄膜电极。制备过程包括纯铝片在草酸溶液中阳极氧化成多孔阳极氧化铝,电化学法去多孔阳极氧化铝的阻挡层,磷酸中扩孔,无电沉积一层钯,再在孔中组装普鲁士蓝。用扫描电镜对支撑体和电极表面形貌进行了表征,用循环伏安法对电极进行了电化学研究。结果表明,这种支撑体孔隙率大于65%,组装的普鲁士蓝(PB)薄膜电极在-0.2～0.6V和0.6～1.2V两个电位窗口内呈现两对稳定的可逆峰,由这种薄膜电极组成的微型PB薄膜蓄电池,容量达到65mC/cm2,表现出良好的充放电性能。