Advanced oxidation technology for H2S odor gas using non-thermal plasma

Non-thermal plasma technology is a new type of odor treatment processing. We deal with H2S from waste gas emission using non-thermal plasma generated by dielectric barrier discharge. On the basis of two criteria, removal efficiency and absolute removal amount, we deeply investigate the changes in electrical parameters and process parameters, and the reaction process of the influence of ozone on H2S gas removal. The experimental results show that H2S removal efficiency is proportional to the voltage, frequency, power, residence time and energy efficiency,while it is inversely proportional to the initial concentration of H2S gas, and ozone concentration. This study lays the foundations of non-thermal plasma technology for further commercial application.     

基于非接触式高效膜蒸馏的低温蒸发技术

膜蒸馏能对放射性废水进行深度净化,但传统直接接触式膜蒸馏技术存在膜通量小、能耗高等不足,工业应用有限。为了克服直接接触式膜蒸馏技术的缺点,发展非接触式膜蒸馏技术,必须建立废水的低温蒸发技术。基于自制的废水低温蒸发装置,采用实验测量和理论模拟的方法,研究了装置蒸发特性与能力。在相同条件下,自制低温蒸发装置性能的实验测量结果与理论计算结果一致;理论计算了该装置在操作范围内蒸发量的最大值为80.6 kg/h,以及将低温蒸发装置尺寸放大为塔径1 m、填料高度3 m时,其最大蒸发量可达到1 143 kg/h;该装置出气冷凝水电导率反映的离子去除效率达到89.5%。低温蒸发装置能为后续膜蒸馏装置提供稳定且充足的待处理湿空气,为非接触式膜蒸馏技术的发展奠定基础。     

Channeltron operating in coincidence mode

We have investigated channeltron operating in coincidence with silicon surface barrier detector for detection of extreme low energy particles. By use of Po-209 radionuclide and silver backing, a radioactive source was prepared as a fine emitter of released α particles, conversion electrons, recoil Pb-205 ions and knock out silver ions. To avoid parasite coincidence events mainly from channeltron anode RC circuit, we have applied appropriate Faraday screens. After getting proper counting rates, composite spectra were recorded. Based on time-of-flight and secondary electron emission coefficient arguments, particular spectra of mentioned particles were extracted. Final experimental data analysis enabled us to found channeltron efficiency curves for electrons, lead ions and silver ions with low detection thresholds at 40 eV, 4 keV and 1.7 keV, respectively.     

Development of Dust Removal System Using Static Electricity for Fusion Experimental Reactors

Tests to collect and transport metallic and non-metallic dust particles have been conducted using static electricity in a vacuum environment to investigate the applicability of a static electricity dust removal system for fusion experimental reactors. The dust particles are charged by electrostatic induction, floated and collected due to the Coulomb force generated by the AC electric field. They are then transported due to the gradient force induced by the electric curtain of the non-uniform travelling-wave electric field. Using a fully insulated electrode with a single-phase AC voltage up to 15kV, aluminum and carbon dust were successfully collected. The highest collection rates for the aluminum and carbon dust were around 30 and 2g/min, respectively. The linear-type electrodes, using as high as 22kV of the three-phase AC voltage, transported aluminum dust up to an angle of 60°. Applying a guide electrode to the linear-type electrode, the transportation rate was approximately doubled and almost constant at every angle, including a 90° angle. The system transported aluminum dust up to the rate of 13 g/min. The influence of the 0.15 T magnetic field on the dust collection and transportation efficiencies was found to be negligible.     

Removal of NO and SO2 in Corona Discharge Plasma Reactor with Water Film

In this paper, a novel type of a corona discharge plasma reactor was designed, which consists of needle-plate-combined electrodes, in which a series of needle electrodes are placed in a glass container filled with flue gas, and a plate electrode is immersed in the water. Based on this model, the removal of NO and SO2 was tested experimentally. In addition, the effect of streamer polarity on the reduction of SO2 and NO was investigated in detail. The experimental results show that the corona wind formed between the high-voltage needle electrode and the water by corona discharge enhances the cleaning efficiency of the flue gas because of the presence of water, and the cleaning efficiency will increase with the increase of applied dc voltage within a definite range. The removal efficiency of SO2 up to 98%, and about 85% of NO~ removal under suitable conditions is obtained in our experiments.     

Characterization of dust collected in EAST after 2019 campaign

Dust presented in experimental advanced superconducting tokamak(EAST) with mixed plasmafacing materials has been collected and characterized for the first time. Dust at different positions in the vessel was collected by vacuum cleaner after the first experimental campaign in 2019. The shape, composition, and size of dust particles have been analyzed using different methods. About80% of the total number of dust particles have size between 20 and 80 μm, and most of dust particles are spherical, while schistose shape, columnar and irregular shape were also found.With the help of energy-dispersive x-ray spectroscopy different elements of dust have been identified, which is generally consistent with the different plasma-facing components in EAST.Both x-ray fluorescence and inductively coupled plasma emission spectrometer are complementary methods for measuring the dust composition quantitatively. It was found that the major components of dust were lithium dust in the form of lithium carbonate and lithium hydroxide, which is due to the routine lithium wall conditioning during EAST operation.     

Fusion Safety Research and Development in JAERI

This paper describes the current status and future plans of the fusion safety research and development regarding to the developments of the dust removal system and safety analysis code and the thermofluid experiments in the Japan Atomic Energy Research Institute (JAERI) for a fusion experimental reactor. The containment of the radioactive material is the key to achieve fusion safety. In the event of accidents, the source terms need to be evaluated with sufficient accuracy. Therefore, in JAERI, the dust characterization have been investigated and the dust removal system using electric force has been developed and tested. A safety analysis code including both thermal and plasma transient analyses under the various event sequences has been developed. Moreover, the preliminary experiments of thermofluid transients in the vacuum vessel such as Ingress of Coolant Event (ICE) and Loss of Vacuum Event (LOVA) have been started and the experimental results using preliminary LOVA/ICE apparatus during 1995–1996 are summarized in this paper.     

Influence of gas atmosphere on synergistic control of mercury and dioxin by nonthermal plasma

In this paper, narrow-pulse power discharge is used to study the synergistic control of mercury and dioxins, in which 1,2,4-trichlorobenzene (TCB) was used as a dioxin analog, by using a self- designed experimental system. The competitive effects of NO, SO₂ and HCl on the TCB removal by non-thermal plasma are discussed. The influence of acid gas on TCB degradation is reflected in the competitive effect. NO has the greatest influence on TCB degradation efficiency. The oxidation efficiency of Hg⁰ decreased by about 10% in all three acidic gas atmospheres, and the effect of each gas component on Hg⁰ oxidation is complex. In the flue gas atmosphere of ‘acid gas+Hg⁰ +TCB’, the mechanism of the synergistic control of Hg⁰ and TCB by the non- thermal plasma is different, which has competition and promotion relationship between each other. The contribution of various flue gas components to the results was complicated, but the overall experimental results show that the synergistic control effect of the system can continue to improve. According to the generated product backstepping, ·OH plays an important role in the synergistic control of the degradation of Hg⁰ and TCB. Through this study, we hope to provide basic research data for the collaborative control of flue gas in the incineration industry.     

旋风组钠气溶胶去除系统性能验证

钠气溶胶是钠冷快堆发生钠火时产生的特征性产物,需通过除尘净化系统对钠气溶胶进行去除净化,以减少排放到环境的放射性剂量和钠气溶胶浓度。采用干式气固分离路线,设计了一套旋风组钠气溶胶去除系统,通过开展真实钠火环境下的钠气溶胶去除试验,考察了金属钠燃烧过程中钠气溶胶浓度变化、粒径分布、压降、去除效率等主要参数,最终认为该系统对钠气溶胶具有很高的去除效率。     

NO reduction using low-temperature SCR assisted by a DBD method

This paper discusses the removal of nitric oxide(NO) with low-temperature selective catalytic reduction driven by a dielectric barrier discharge with ammonia(NH_3) as a reductant. We explored the effects of NH_3, O_2, temperature and water under different applied voltage on NO removal at atmospheric pressure. The results showed that when the gas concentration ration of NH_3/NO was 0.23–0.67, the NO removal efficiency and the energy consumption was acceptable. The NO removal efficiency reached 84% under an applied voltage of 7 kV, 400 ppm NO and 90 ppm NH_3 at a temperature of 150 ℃. Water vapor had a negative effect because NO formation reactions were strengthened and NH_3 was oxidized directly rather than reduced NO molecules. The outlet gas components were observed via Fourier transform infrared spectroscopy for revealing the decomposition process and mechanism.     

Theoretical research on the transport and ionization rate coefficients in glow discharge dusty plasma

The electron kinetic model for investigating the transport and ionization rate coefficients of argon glow discharge dusty plasma is developed from the Boltzmann equation.Both of the electron-neutral and electron-dust collisions are considered as collision terms in the kinetic equation.The kinetic equation is simplified by employing the local approximation and nonlocal approach under the same discharge conditions,and the corresponding simplified kinetic equations are known as local and nonlocal kinetic equations respectively.Then the electron energy distribution function(EEDF)is obtained by numerically solving the local and nonlocal kinetic equations and the dust charging equations simultaneously.Based on the obtained EEDFs,the effective electron temperature,electron mobility,electron diffusion coefficient and ionization rate coefficient are calculated for different discharge conditions.It is shown that the EEDFs calculated from the local kinetic model clearly differ from the nonlocal EEDFs and both the local and nonlocal EEDFs are also clearly different with Maxwellian distributions.The appearance of dust particles results in an obvious decrease of high energy electrons and increase of low energy electrons when axial electric field is low.With the increase of axial electric field,the influence of dust particles on the EEDFs becomes smaller.The electron mobility and diffusion coefficients calculated on the basis of local and nonlocal EEDFs do not differ greatly to the dust-free ones.While,when dust density nd=10^6 cm^?3,the electron mobility increases obviously compared with the dust-free results at low axial electric field and decreases with the increasing axial electric field until they are close to the dust-free ones.Meanwhile,electron diffusion coefficients for dusty case become smaller and decrease with the increasing axial electric field.The ionization rate coefficients decrease when dust particles are introduced and they approach the dust-free results gradually with the increasing axial electric field.     

Experimental study on toluene removal by a two-stage plasma-biofilter system

Volatile organic compounds (VOCs) are typical pollutants that affect air quality. Discharge plasma is thought to be a potential method that can remove VOCs from flue gas. In this experiment, pulsed corona discharge plasma combined with a biological tower was carried out to remove the benzene series, and toluene was selected as the typical VOC. The results indicated that the removal efficiency of toluene by pulsed corona plasma was slightly higher than that of direct current (DC) corona plasma, while its energy efficiency was much higher than DC corona plasma. Under the optimal experimental conditions of pulse voltage 8.5 kV, initial toluene concentration 1400 mg m−3, and toluene flow rate of 12 l h−1, the toluene removal efficiency reached 77.11% by the single method of pulsed corona discharge plasma, and the energy efficiency was up to 1.515 g/(kW·h) under the pulse voltage of 4.0 kV. The trickling biofilter was constructed by using the screened and domesticated Acinetobacter baumannii, and the highest toluene removal efficiency by the pulsed corona discharge plasma combined with the trickling biofilter rose up to 97.84%. Part of the toluene was degraded into CO2, H2O, and some intermediate products such as o-diphenol under the influence of Acinetobacter baumannii. When the remaining waste gas passed through the discharge plasma reactor, the benzene ring structure could be directly destroyed by the collision between toluene and plasma. Meanwhile, O·, OH·, and some other oxidizing radicals generated by the discharge also join into the oxidative decomposition of toluene and its intermediate products, thereby further improving the removal efficiency of toluene. Therefore, the two-stage plasma-biofilter system not only showed a high toluene removal efficiency, but also had a good energy efficiency. The results of this study will provide theoretical support and technical reference for industrial VOC treatment.     

Analysis of the operating parameters of a vortex electrostatic precipitator

A vortex electrostatic precipitator(VEP) forms a vortex flow field within a precipitator by means of the vertical staggered layout of the double-vortex collecting plate facing the direction of the gas flow.The ion concentrations within the precipitator can be significantly increased.Correspondingly,the charging and coagulation rates of fine particles and particle migration velocity are significantly improved within the VEP.Since it can effectively collect fine particles and reduce precipitator size,VEPs represent a new type of electrostatic precipitator with great application potential.In this work the change curve of the external voltage,gas velocity,row spacing and effective collecting area influencing the precipitation efficiency were acquired through a single-factor experiment.Using an orthogonal regression design,attempts were made to analyze the major operating parameters influencing the collecting efficiency of fine particles,establish a multiple linear regression model and analyze the weights of factors and then acquire quantitative rules relating experimental indicators and factors.The regression model was optimized by MATLAB programming,and we then obtained the optimal factor combination which can enhance the efficiency of fine particle collection.The final optimized result is that:when gas velocity is 3.4 ms~(-1),the external voltage is 18 kV,row spacing is 100 mm and the effective collecting area is 1.13 m~2,the rate of fine particle collection is 89.8867%.After determining and analyzing the state of the internal flow field within the VEP by particle image velocimetry(PIV),the results show that,for a particular gas velocity,a vortex zone and laminar zone are distinctly formed within the VEP,which increases the ion transport ratio as well as the charging,coagulation and collection rates of fine particles within the precipitator,thus making further improvements in the efficiency of fine particle collection.     

Numerical and experimental investigation of plasma plume deflection with MHD flow control

This paper presents a composite magneto hydrodynamics(MHD) method to control the lowtemperature micro-ionized plasma flow generated by injecting alkali salt into the combustion gas to realize the thrust vector of an aeroengine.The principle of plasma flow with MHD control is analyzed.The feasibility of plasma jet deflection is investigated using numerical simulation with MHD control by loading the User-Defined Function model.A test rig with plasma flow controlled by MHD is established.An alkali salt compound with a low ionization energy is injected into combustion gas to obtain the low-temperature plasma flow.Finally,plasma plume deflection is obtained in different working conditions.The results demonstrate that plasma plume deflection with MHD control can be realized via numerical simulation.A low-temperature plasma flow can be obtained by injecting an alkali metal salt compound with low ionization energy into a combustion gas at 1800–2500 K.The vector angle of plasma plume deflection increases with the increase of gas temperature and the magnetic field intensity.It is feasible to realize the aim of the thrust vector of aeroengine by using MHD to control plasma flow deflection.     

Decomposition of dioxin-like components in a DBD reactor combined with Hg/Ar electrodeless ultraviolet

A new combined reactor with Hg/Ar electrodeless ultraviolet(EDUV)activated by DBD for 3,4-dichlorodiphenyl ether abatement is presented.The effect of specific input energy and feeding gas component on 3,4-dichlorodiphenyl ether removal efficiency has been explored.Compared with a single DBD system,this new combined process performed a significant promotion on 3,4-dichlorodiphenyl ether abatement.Experiment results verified that active oxygen clearly contributed to the synergistic activity of DBD-EDUV system.Results of emission spectra showed that UV radiation of 253.7 nm could be detected in the DBD-EDUV system.Further,the products of DBD-EDUV process were analyzed via gas chromatographymass spectrometer(GC-MS)to reveal involved decomposition mechanism.     

模拟气体标准源法校准反应堆惰性气体监测仪效率

为准确校准惰性气体监测仪对气体源的γ射线全能峰效率,制备了以可发性聚苯乙烯（EPS）颗粒为基质材料的马林杯放射性模拟气体标准源,模拟气体标准源装样密度为4.1 kg/m³,其中含²⁴¹Am、¹⁰⁹Cd、⁵⁷Co、⁵¹Cr等8种单能γ射线发射核素。利用该模拟气体标准源,对反应堆惰性气体现场监测仪的HPGe探测器γ射线全能峰效率进行了校准,校准覆盖能区为60～1836 keV,校准的效率标准不确定度最大为4.4%。同时采用点源代表点法进行了效率校准,并将模拟气体标准源与代表点位置处的点源效率校准结果进行对比,发现在校准能区内二者的效率比不为常数,效率偏差最大达28%,通过效率传递系数可减小偏差,且可得到效率传递系数拟合曲线。最后在81 keV能量点处,得到模拟气体标准源与标准气体源的效率比为1.26,此值可作为模拟气体标准源的实际应用参考。     

The Degradation of Organic Pollutants by Bubble Discharge in Water

Organic pollutants could be degraded by using bubble discharge in water with gas aeration in the discharge reactor and more plasma can be generated in the discharge process.When pulsed high voltage was applied between electrodes with gas aerated into the reactor,it showed that bubbles were broken,which meant that breakdown took place.It could also be observed that the removal rate of phenol increased with increasing discharge voltage or pulse frequency,and with reducing initial phenol concentration or solution electric conductivity.It could remove more amount of phenol by oxygen aeration.With increasing oxygen flow rate,the removal rate increased.There was little difference with air or nitrogen aeration for phenol removal.The solution temperature after discharge increased to a great extent.However,this part of energy consumption did not contribute to the reaction,which led to a reduction in the energy utilization efficiency.     

厚GEM探测器对γ射线探测效率的研究

作为一种新型微结构气体探测器(MPGD),厚型气体电子倍增器（THGEM）用于较高能量光子探测是新的尝试。为了解其探测机理及探测效率的主要影响因素,利用多粒子输运软件、多物理耦合仿真软件及气体电离模拟软件,分别建立了光子与探测器相互作用模型、电子漂移扩散模型和气体电离模型。通过仿真得到了漂移极内表面和膜上电极的电子出射概率,¹³⁷Cs在漂移极内表面产生激发电子的能量分布和角分布。动态模拟了电子在特定电场中的漂移和横向扩散行为,定量计算了原初电子的入孔数量和入孔效率。最后通过实验验证,证明增大漂移区距离和提高THGEM膜间电压可显著提高THGEM对γ射线的探测效率。     

紧凑型磁质子反冲谱仪磁分析系统的能量刻度

介绍了一种用于多种特定环境下脉冲氘氚聚变中子能谱测量的紧凑型磁质子反冲谱仪的磁分析系统。通过三维粒子输运和蒙特卡罗模拟对磁分析系统性能进行了分析,使用CR-39径迹探测器和多个能量α单能粒子对系统进行了能量刻度。结果表明,磁分析系统具有良好的能量离散与聚焦性能,对给定能量范围的反冲质子,能够以1.5%~2.1%的能量分辨率实现（0.5~1.4）×10^－4的探测效率。