Numerical modeling of near corona wire electrohydrodynamic flow in a wire-plate electrostatic precipitator

Numerical modelling of the flow velocity fields for the near corona wire electrohydrodynamic (EHD) flow was conducted. Solutions of the steady, two-dimensional momentum equations have been computed for a wire-plate type electrostatic precipitator (ESP). The equations were solved in the conservative finite-difference form on a fine uniform rectilinear grid of sufficient resolution to accurately capture the momentum boundary layers. The numerical procedure for the differential equations was used by SIMPLEST algorithm. The CFD code coupled with Poisson's electric field, ion transport equations and the momentum equation with electric body force, was used for the numerical simulation with the Chen-Kim k-epsiv turbulent model. The numerical results show that EHD secondary flow was clearly visible in the downstream regions of the corona wire despite the low Reynolds number for the electrode (Re _cw=12.4). Secondary flow vortices caused by the EHD increases with increasing discharge current or EHD number, hence pressure drop of ESP increases     

125 MW机组电除尘器的技术改造

介绍了株洲华银火力发电有限公司2台125MW机组电除尘器增效改造的方法和取得的良好效果,为在不动土建的情况下,将电厂电除尘器三电场改为四电场提供了参考经验。     

Breathe easy [electrostatic precipitator]

The recent development and availability of high speed, high power devices have enabled a new breed of power supply to be designed for electrostatic precipitator energization duties. These new units are based on high frequency, high voltage or switch mode power supplies operating at frequencies up to 50 kHz. One such unit was developed by researchers at the University of Leicester and RWE. The unit features a 20 kHz frequency switched mode based power supply (SMPS) for electrostatic precipitation in a coal-fired power station and an output voltage of 50 kV at 1 A continuous rating. This paper describes this and other similar SMPS systems for use in electrostatic precipitation.     

Automatic control and management of electrostatic precipitator

The efficient operation of an electrostatic precipitator (ESP) in practice depends upon many variables, such as charging method, particle size, gas flow, temperature, dust resistivity, etc. With air pollution control requirements becoming increasingly stringent, it is essential to closely monitor and accurately control the key parameters of an ESP control system. The efficient functioning of an ESP normally means minimizing power consumption and maximizing dust collection. Several control strategies can be adopted to meet this broad requirement. In this paper, a distributed control technique of an ESP, which uses the actual dust emission and boiler load as feedback inputs has been explained. The electrostatic precipitator management system, which is a system designed by Bharat Heavy Electricals Ltd., Hyderabad, India, to meet the above control strategies using the distributed architecture to achieve efficient ESP operation is also described     

影响静电除尘器效率的控制因素

通过研究影响静电除尘器除尘效率的几个常见可控因素，分析漏风、比电阻、振打周期及电场闪络频率对除尘效率的影响，并提出相应解决措施，使静电除尘器保持更高的除尘效率。     

Finite element method investigation of electrostatic precipitator performance

This paper aims at analysis of the monopolar ionized field in electrostatic precipitator. A numerical model for simulating precipitation of particles in electrostatic precipitator is discussed in this paper. It includes all essential phenomena affecting the process. An iterative finite‐element technique is used to solve Poison's equation. We proposed the introduction of a potential corresponding to the critical minimum ionization field directly in the finite element formulation as a Dirichlet condition. The theoretical migration velocity is obtained by balancing the drag force with the Coulomb force or electrostatic force acting on a particle. We used the model introduced by Cochet for predicting a particle charge. The model assumes that a particle of the same size attains an equivalent maximum amount of charge for a charging time equal to infinity. Particles influence the electrical field, flow field, electrical migration velocity, gas discharge, particle charge and collection efficiency. Copyright © 2014 John Wiley & Sons, Ltd.     

浅析电除尘器的振打清灰方式

对顶部电磁振打电除尘器与侧部挠臂锤振打电除尘器在振打机理、运行可靠性、维护性能、成本等方面进行比较分析，认为电除尘器的顶部振打清灰方式值得选取。     

Pulse energization system of electrostatic precipitator forretrofitting application

A pulser module has been developed for electrostatic precipitators for upgrading the performance of existing plants. The module is inserted between the existing DC power supply and corona electrodes. A sawtooth voltage appears on the corona electrodes at a switching frequency, including at its leading edge a transient LC oscillation with a very sharp first peak and fast-decaying amplitude. This acts as the submicrosecond pulse energization, producing very active negative streamers in uniform distribution along the entire length of corona wires of the conventional construction. The average of the sawtooth voltage produces a DC field between the corona and the collecting electrodes. This direct-coupled pulse energization indicates in present laboratory tests exactly the same collection performance as the hitherto most effective submicrosecond pulse energization using a coupling capacitor and a DC bias voltage. A specific feature of the present pulse energization system is its simplicity in construction and low initial and operating costs     

Two-stage-type electrostatic precipitator re-entrainment phenomenaunder diesel flue gases

One of the applications of the electrostatic precipitator (ESP) is the cleaning of air to increase the visibility index in highway tunnels. Particles floating in air in highway tunnels are mainly carbon. Collection efficiency of a large particle diameter in an ESP often decreases when the ESP collects carbon particles which have low electric resistance. Collection efficiency often becomes negative in an experimental ESP. The negative collection efficiency means that the particle concentration flowing downstream is greater than that upstream in the ESP. This phenomenon is explained as the re-entrainment of particles. In this paper, experiments were carried out to investigate the cause of the decrease in efficiency of particle collection of the ESP. The time characteristic of the collection efficiency and the distribution of particle size on the collection electrodes were studied. Experimental results showed that the decrease in the collection efficiency was caused by re-entrainment of particles during the ESP operation. The effect of gas-flow velocity on the collection efficiency of the ESP was also investigated to study the cause of re-entrainment phenomena. The result showed that the re-entrainment phenomena depended on the gas-flow velocity     

静电除尘器供电控制方式探讨

本文通过对静电除尘器在“火花跟踪”和“间歇供电”方式下除尘效率及电耗的比较 ,认为应重视静电除尘器供电方式的选择。在粉尘比电阻较高时 ,选用“间歇供电”方式不仅能提高除尘效率 ,还可大幅降低电场电耗。     

电除尘器电源控制系统的改造

通过对宁夏石嘴山发电有限责任公司电除尘器除尘效果不佳的原因分析,提出了较为合理的改造方案。实践证明:经过改造后的电除尘器,提高了除尘效率,降低了出口烟尘排放浓度,同时减少了电能损耗与振打次数,取得了一定的社会与环保效益。     

电除尘器电场的工作特性分析在生产实际中的应用

针对哈三电厂电除尘器在实际运行中存在的问题,应用电除尘器工作特性分析方法,能较快的查找原因,解决实际问题,减少检修盲目性,提高设备的完好率,从而提高了电除尘器的效率。     

DCM工作模态下LCC静电除尘变压器仿真设计

通过在Saber中搭建LCC谐振电路,在固定开关频率和占空比下,根据输出功率,分析了高频变压器的原边电流、电压和视在功率。结合传统AP法,计算出合适的绕制参数和磁芯尺寸。利用Maxwell软件,在3D瞬态场下,分析变压器原副边的耦合系数,确定合适副边对原边的漏感值。再利用Saber中自带的磁元件工具箱,在2D环境下分析绕组分布和层间电容值。仿真结果最终得到符合谐振要求的寄生参数。仿真设计有助于在实际制作变压器之前,对绕制参数及工艺提供可靠指导。     

Quasi-static and dynamical computation of V-I characteristics of adust-loaded pulse-energized electrostatic precipitator

This paper describes an accurate model and a new procedure for the numerical computation of the electric field, current and charge density, in a pulse energized electrostatic duct-type precipitator, in presence of dust. The proposed model is compared to the classical steady-state model used in the past. The old model shows nonphysical bumps and discontinuity whereas the new approach predicts the natural transient behavior of electrical quantities. The partial differential equations governing the transient phenomena are solved by means of an implicit-explicit finite-difference time-domain method, which ensures a fast computation. The obtained results, compared with experimental values, show a good accuracy of the presented method     

以叠加脉冲电源方法提高电除尘器效率的试验

介绍电除尘用脉冲电源的特点,详细介绍电除尘器叠加脉冲电源试验的工况和试验方案。试验结果表明,静电除尘器在叠加脉冲电源后,出口粉尘浓度明显降低,脉冲电源使电除尘器取得了比使用工频电源时更高的除尘效率。     

Three-dimensional ionic wind and electrohydrodynamics of tuft/point corona electrostatic precipitator

The two-dimensional flow interaction between the primary flow and the secondary flow (often called an electric wind or ionic wind) in the wire-duct electrostatic precipitator (ESP) has been investigated theoretically and experimentally in the past. However, the analysis was limited to the two-dimensional, which is acceptable only for the positive polarity and small tuft spacing. The negative corona, commonly used for the industrial ESPs, generates tufts along the corona wire and the point coronas on the discharge wire and requires three-dimensional analysis. Three-dimensional electric field and space-charge density distributions, and the flow interaction between the primary flow and secondary flow, i.e., electrohydrodynamics were investigated. The computational results show that the secondary flow distribution consists of a donut-shaped ring from each tuft or corona point, which was predicted by the first author 16 years ago. When the primary flow exists, a pair of spiral rings, like Goertler vortices, is formed in the direction of the primary flow. The flow interaction was described using dimensionless number N/sub EHD/, which is the ratio of the ionic wind velocity to the primary flow velocity. The effects of particle motion in the electrohydrodynamic field in the tuft/point corona ESPs are discussed.     

Mercury and other trace elements removal characteristics of DC andpulse-energized electrostatic precipitator

Removal of zinc-rich ash and mercury from a gas stream using prototype electrostatic precipitators (ESPs) has been investigated. Dust particles collected from the thermal plasma ash volume reduction system of the Matsuyama, Japan, municipal incineration plant were used to study the performance of an ESP to collect zinc-rich ash. The ash was analyzed by neutron activation analysis using the nuclear reactor at McMaster University, Hamilton, ON, Canada. Collection efficiency as high as 99.9% was obtained in the removal of Zn from the flue gas with DC energization of the ESP. The mercury concentration was measured using a cold vapor atomic absorption spectrometer after sampling (OSHA-140 method) from the flue-gas stream. As a function of concentration, the mercury collection efficiency was higher at a higher concentration of mercury. Higher collection efficiency was obtained under negative DC energization compared to other modes of energization of the ESP; however, power consumption under the pulse application was much smaller compared to DC energization     

电除尘器效率降低原因分析及对策

针对新余发电有限责任公司电除尘器除尘效率下降的情况,分析其存在的主要问题,简要介绍所采取的改造措施:将相应的电除尘器一电场阴极线更换为管型芒刺线;阳极板下部加装加强板;阴极振打轴承改为托滚式轴承等。改造实施后电除尘器除尘效果明显改善,可靠性得到提高。本电除尘器的改造经验对其他电厂解决同类问题具有一定借鉴意义。