DC corona discharge influence on chemical composition in mixtures of natural gas with air and its combustion exhaust with air

Experiments in dc supplied corona discharge in natural gas + air mixture and in combustion exhaust of natural gas + air mixture were realized. The influence of discharge on CO, CO₂, NO _x and other minority components was studied using IR absorption spectrometry. Production of NCO radicals in gas and consequent formation of NCO containing surface layers on a plate electrode was detected. In natural gas + air mixture after about 1 min oxygen poor combustion exhaust was produced due to slow combustion by corona discharge. Occurrence of various pulses in discharge current was typical.     

The influence of water vapour and temperature on depletion of carbon monoxide in D.C. corona discharge

The plasmochemical and/or electrocatalytical reactions of carbon monoxide with water vapour were studied. Dc corona discharge of both polarities at room temperature and temperatures enhanced up to 70°C was applied at pressures close to atmospheric. The reaction products were analysed by IR absorption spectrometry. The main products in the gas phase were CO₂ and CH₄. The reactions are influenced by the formation of a catalytically active surface layer on electrodes. The composition of this layer depends on the polarity of electrode.     

The Conversion of NOx in a Corona Discharge with an Electrode Material Variation

The spatial and surface chemical products and effectiveness of NO_x removal (abbreviated deNO_x) under the corona discharge action at atmospheric pressure were investigated. The influence of high-voltage electrode material on a discharge character and the heterogeneous influence of the electrode surface are also reported in the article. The qualitative analysis was performed using infrared absorption spectrometry. Special attention was paid to NO and NO₂ calibration measurements.     

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

快脉冲直线变压器型驱动源(FLTD)是近年来快速发展的新型脉冲功率源技术,多采用多间隙气体开关作为开关器件。电晕均压措施有利于提升开关击穿性能,但不同气体中电晕放电有显著区别。本文首先研究了空气中针电极对单间隙电晕放电特性的影响,确定了电晕针电极的尺寸,之后研究了N2,CO2,SF6/N2混合气体、C4F7N/N2混合气体中的电晕放电特性,研究了电晕均压6间隙气体开关击穿电压及其稳定性随气体种类和气压的变化规律。实验结果表明,N2中电晕电流较大且不稳定,空气中电晕电流比N2中低,且电晕放电较为稳定,微量强电负性气体加入会极大降低电晕放电电流。当采用空气和N2作绝缘介质时,气体开关击穿电压随气压升高线性增加,但存在低值击穿,微量强电负性气体混合N2可显著提升击穿电压的稳定性。1%SF6/99%N2混合气体在0.18 MPa时,击穿电压约为197.33 kV,标准偏差占击穿电压比例为1.50%,1%C4F7N/99%N2混合气体在0.15 MPa时,击穿电压约为190.42 kV,标准偏差为0.55%。这表明,微量环保替代气体C4F7N与N2的混合气体对于提升多间隙气体开关击穿电压稳定性有显著作用。     

Clean-up by gas-particle transformation under the action of acorona discharge: application to volatile iodine compounds

The ionization of gas induced by the establishing of a corona discharge causes gas-particle transformation of the iodomethane. A radioactive tracer (iodine 131) is used to produce elementary iodine balances for the overall process. The experimental results show the benefit of this procedure for the purification of radioactive gaseous iodine compounds. There is a transfer of activity from the gaseous phase to the solid phase. Transformation levels can reach 80% under our experimental conditions. The experimental study of aerosols produced downstream of the corona discharge evidences the need to carry out this process in three successive stages     

Sulfur dioxide (SO2) gas transfer process enhanced by corona discharge

The sulfur dioxide (SO₂) gas transfer process in a corona discharge field has been studied. The experiments were conducted to investigate the effects of voltage, length, and height of the discharge area on the electric transfer of SO₂ as well as on the desulphurization efficiency. Experimental results show that corona discharge can facilitate the SO₂ gas transfer process. The rate and efficiency of desulphurization increase with increasing voltage, length of discharge area, and input power. The addition of a uniform electric field to the corona-discharge field improves the electronic transfer of SO₂. Measured desulphurization efficiency was as high as 95%, and the augmentation of desulphurization efficiency due to corona discharge was nearly 50% under the conditions tested.     

Conversion of nitrogen oxides in N2:O2:CO2 and N2:O2:CO2:NO2 mixtures subjected to a dc corona discharge

This paper concerns the influence of a direct current (dc) corona discharge on production and reduction of NO, NO₂ and N₂O in N₂:O₂:CO₂ and N₂:O₂:CO₂:NO₂ mixtures. The corona discharge was generated in a needle-to-plate reactor. The positively polarized electrode consisted of 7 needles. The grounded electrode was a stainless steel plate. The gas flow rate through the reactor was varied from 28 to 110 cm³/s. The time-averaged discharge current ranged from 0 to 6 mA. It was found that in the N₂:O₂:CO₂ mixture the corona discharge produced NO, NO₂ and N₂O. In the N₂:O₂:CO₂:NO₂ mixture the reduction of NO₂ was between 6–56%, depending on the concentration of O₂, gas flow rate and corona discharge current. The NO₂ reduction was accompanied by production of NO and N₂O. The results show that efficient reduction of nitrogen oxides by a corona discharge cannot be expected in the mixtures containing N₂ and O₂ if reducing additives are not employed.     

多针电晕增强大气压辉光放电稳定性研究

利用多针电晕增强放电装置，在无气流和存在高速气流的情况下都得到了稳定的大气压辉光.通过纪录发光图片、电流-电压波形和伏安特性曲线的方法对影响放电稳定性的因素做了细致地研究，发现了在从电晕放电到辉光放电的过程中存在着过渡阶段，表现为出现带有直流成分的Trichel脉冲.气流速度、极板间距以及针尖锥度和凹坑曲率半径的匹配程度都对放电的稳定性和电流密度有着重要的影响. 关键词： 大气压辉光放电 多针电晕 等离子体     

多间隙气体开关电晕均压结构优化

电晕针均压的多间隙气体开关,其各间隙电晕电流一致性会直接影响开关的耐压稳定性。在工作气压0.1,0.2,0.3,0.4 MPa条件下,实验测量了六间隙气体开关在不同电压下的各间隙电晕电流。结果显示,针-板间隙电晕电流明显高于针-杆间隙电晕电流。对针-板间隙进行结构调整并进行三维静电场仿真。对调整结构后的针-板间隙进行电晕电流测试,测试数据的变化趋势与仿真结果相符。基于实验和仿真结果,优化了针-板间隙中电晕针的高度,充电25 kV时,开关各间隙电晕电流的相对标准偏差最大为8%。     

Degradation of persistent pharmaceuticals in aqueous solutions by a positive dielectric barrier discharge treatment

The degradation of the pharmaceuticals carbamazepine, clofibric acid, and iopromide in aqueous and landfill leachate containing solutions by corona discharge over a liquid surface was investigated. Two barrier electrodes, which provided an atmospheric pressure corona, were mounted above a transport roll, which moved a thin water film of test solution from the sample reservoir. Numerous tests were performed on single, mixed, and landfill leachate containing solutions with various combinations of powers, rotational speeds, air gaps, and exhaust restrictions. Best results were obtained with the highest rotational speed, a reduced exhaust, and an electrode air gap of 1.5 mm.     

Theory and application of cyclone with impulse electrostatic excitation for cleaning molecular gas

This paper introduces the structure, characteristics and operating principle of a cyclone impulse electrostatic precipitation (CIESP), and presents the solid–gas separation mechanism of CIESP. The hydromechanics equations of particles in solid–gas separation are set up with the goal of analyzing the characteristics of impulse corona discharge. The application of CIESP for cleaning molecular gas in a catalyst plant is explained. We conclude that CIESP is very suitable for cleaning sticky dust particles from exhaust gases of molecular sieve catalyst plant, and has high overall collection efficiency, while the migration velocity is approximately twice that of the electrostatic precipitation (up to 0.15–0.18 m/s). The theoretical formula for particle migration velocity is experimentally verified.     

羧基丁苯胶乳中结合苯乙烯含量的红外光谱测定法

本文介绍了用红外光谱法测定羧基丁苯胶乳中结合苯乙烯含量的方法，通过该方法分别选择１４９５ｃｍ~（－１）作为苯乙烯的芳烃Ｃ＝Ｃ伸缩振动特征吸收带和９７０ｃｍ~（－１）作为丁二烯的反式Ｃ＝Ｃ非平面摇摆振动特征吸收带。结果求得直线回归方程，相关系数，相对标准偏差，精度范围等。本方法简单、快速、选择生强，已成功地应用于羧基丁苯胶乳中结合苯乙烯含量的测定。     

低气压长间隙介质阻挡放电的光谱诊断

设计了一种电极间隔为10 cm的介质阻挡放电装置,以氩气为工作气体,在低气压下产生等离子体。采用发射光谱法,研究了放电空腔内等离子体电子温度和电子密度随空间位置的变化规律。等离子体电子温度的变化通过使用Corona模型计算获得,等离子体电子密度的变化通过分析Ar原子750.4 nm谱线强度变化得到。实验发现空腔内不同位置的等离子体电子温度和电子密度是不同的。当测量位置从阴极向阳极移动时,电子温度先略上升而后迅速下降,再缓慢上升;电子密度先缓慢而后迅速地增大。     

Corona discharge processes

Applications of corona discharge induced plasmas and unipolar ions are reviewed. Corona process applications emphasize one of two aspects of the discharge: the ions produced or the energetic electrons producing the plasma. The ion identities depend on the polarity of the discharge and the characteristics of the gas mixture, specifically on the electron attaching species. The electron energies depend on the gas characteristics and on the method of generating the corona. In general, in an application using ions, the corona induced plasma zone will occupy a small fraction of the total process volume, while a process using the electrons will fill most of the volume with the plasma. Current state-of-the knowledge of ionized environments and the function of corona discharge processes are discussed in detail     

高压放电对飞灰表面特性的影响

高压放电对飞灰表面特性会产生影响从而改变飞灰颗粒的荷电特性。使用高压窄脉冲电源大幅提高静电除尘器的放电电压,通过对不同电压放电前后飞灰表面特性进行分析,得到其影响规律。随着放电电压的升高,飞灰表面受到越来越严重的破坏,从开始相对光滑完整的表面结构逐渐转变为具有蜂窝状的新结构。放电电压越高,蜂窝的孔密度越高,孔径越小。复...     

红外吸收法准确测量低硫煤中硫元素含量

采用同步热分析-红外光谱联用仪测定煤样在程序升温条件下的差示扫描量热-热重曲线和红外吸收光谱,并通过红外吸收光谱定性鉴别燃烧气体产物。重点研究了高温燃烧-红外吸收法,即通过测量煤燃烧气体产物中二氧化硫的浓度,间接地测量煤中硫含量。该方法方便快速,重复性较好。研究发现,用不同的含硫化合物和不同的煤标准物质校准仪器,同一个煤样的硫含量结果偏差很大,即标准物质和煤样中硫元素化学形态的差别导致系统误差。采用时间-红外吸收强度曲线分析煤中高温硫和低温硫的组成,然后选择与被测煤样硫元素组成接近的煤标准物质校准仪器,因而,消除了标准物质和样品间硫元素化学形态差别导致的系统误差。另一个方面,传统的高温燃烧-红外吸收法使用多点校准方法,即通过测定多个质量的标准物质,绘制硫质量-仪器响应信号强度的工作曲线;采用单点校准方法,调节标准物质和煤样的质量,使得两者释放的硫元素质量相近,然后间隔测量煤标准物质和煤样,因而消除了红外吸收池的漂移的影响,提高了煤样硫含量结果重复性。以上述优化的方法测量一种低硫无烟煤和一种低硫烟煤,硫含量测量结果及标准偏差分别为0.345%(0.004％)和0.372％(0.008％)。经过评定,两种煤样的硫含量结果的不确定度(U,k=2)分别为0.019%和0.021%。两个主要创新在于用高温硫和低温硫组成相近的煤标准物质校准仪器,以及采用测量和校准交替进行的单点校准方法。改进后的测量方法,准确性明显好于ASTM D5106的规定值,具有一定的应用推广价值。     

Removal of NOx from NO2∶NO∶N2 mixture by a pulsed and dc streamer corona in a needle-to-plate reactor

The results of laboratory experiments on reduction of NO _x in the oxygen free gas mixture NO₂NON₂ simulating exhaust gas, by means of pulsed and dc streamer corona discharges generated in a needle-to-plate reactor have been presented. The results show that the dc corona discharge is more efficient in De-NO _x process than the pulsed corona discharge. This is in contrast to the results obtained in the wire-to-cylinder reactors where the pulsed corona discharge removes NO _x more efficiently. The results also lead to the conclusion that in the dc streamer corona discharge the short pulses and long interelectrode distances are recommended in order to increase the NO _x conversion rate.Presented at 17^th Symposium Plasma Physics and Technology, Prague, June 13–16, 1995.This work was financially supported by the Polish Academy of Sciences (projects IMP 3.1 and 3.3) and by the Polish Committee for Scientific Research (KBN Grant No. P40103304).     

Optical characteristics of a unipolar corona discharge in working media of high pressure lasers on Ne(3s-3p) and Ar(3p-4d) atoms

The characteristics of a corona discharge in He-Ne and He-Ne-Ar mixtures were investigated at pressures of 50–350 kPa. An amply homogeneous stationary discharge of high pressure was obtained in the external zone of the corona discharge. This discharge can be used in making inversion of the transition of Ne and Ar atoms. Investigation of the kinetics of plasmochemical processes in a dense rare gas plasma was performed.     

废气再循环和添加剂对高辛烷值燃料HCCI燃烧的影响

本文对废气再循环(EGR)和十六烷值改进荆-过氧化二叔丁基(DTBP)对高辛烷值燃料HCCI燃烧的影响进行了研究。实验结果表明:辛烷值为90的燃料(RON90)只能在高温高负荷下才能运行HCCI燃烧模式;在其中加入少量的DTBP后,RON90实现HCCI燃烧的工况范围向低温低负荷下大幅度拓展。加入添加剂后,低负荷性能改善的同时,浓混合气的着火时刻可以通过EGR将含添加剂燃料的着火时刻推迟到上止点附近,从而大幅度提高热效率,降低了燃料消耗率。     

IR absorption spectrum (4200–3100 cm) of H2O and (H2O)2 in CCl4. Estimates of the equilibrium constant and evidence that the atmospheric water absorption continuum is due to the water dimer

IR absorption spectra, 4200–3100 cm⁻¹, of water in CCl₄ solutions are presented. It is shown that for saturated solutions significant amounts of water are present as dimer (ca. 2%). The IR spectra of the monomer and dimer are retrieved. The integrated absorption coefficients of the monomer absorption are significantly enhanced relative to the gas phase values. The dimer spectrum consists of 5 bands, of which 4 were expected from data from cold beams and cold matrices. The origin of the “extra” band is discussed. In addition it is argued that the dimer absorption bands intensities must be enhanced relative to the gas phase values. Based on recent calculations of band strengths, and observed frequency shifts relative to the gas phase, the intensity enhancement factors are estimated as well as the monomer/dimer equilibrium constant in CCl₄ solution at T=296 K (K_c=1.29 mol⁻¹ L). It is noted that the observed dimer spectrum has a striking resemblance with the water vapour continuum determined by Burch in 1985 which was recently remeasured by Paynter et al. and it is concluded that the atmospheric water absorption continuum in the investigated spectral region must be due to water dimer. Based on the newly published spectral data a revised value of the gas phase equilibrium constant is suggested (K_p=0.035 atm⁻¹ at T=296 K) as well as a value for the standard enthalpy of formation, ΔH⁰=15.4 kJ mol⁻¹.