Process simulation and optimization of flow field in wet electrostatic precipitator

To improve the dust removal performance of the wet electrostatic precipitator(WESP), a flow field optimization scheme was proposed via CFD simulation in different scales. The simplified models of perforated and collection plates were determined firstly. Then the model parameters for the resistance of perforated and collection plates, obtained by small-scale flow simulation, were validated by medium-scale experiments. Through the comparison of the resistance and velocity distribution between simulation results and experimental data, the simplified model is proved to present the resistance characteristics of perforated and collection plates accurately. Numerical results show that after optimization, both the flow rate and the pressure drop in the upper room of electric field regions are basically equivalent to those of the lower room, and the velocity distribution in flue inlet of WESP becomes more uniform. Through the application in practice, the effectiveness and reliability of the optimization scheme are proved, which can provide valuable reference for further optimization of WESP.

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 m s-1, the external voltage is 18 kV, row spacing is 100 mm and the effective collecting area is 1.13 m2, 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.

Pyrometallurgical Removal of Arsenic from Electrostatic Precipitators Dusts of Copper Smelting

This work describes the experimental results of pyrometallurgical removing of arsenic from the dust collected in the electrostatic copper precipitators within the gas cleaning system of a Copper Flash Smelting Furnace. The generation of dust in the copper smelting worldwide ranges from 2 - 15 wt% per ton of a copper concentrate. In Chile, copper smelters produce approximately 110 kt/y of dust with a concentration of arsenic between 1 and 15 wt%. The dust is a complex of metals oxides and sulfurs with copper concentrations greater than 10 wt% and relatively high silver concentrations. Since its high arsenic concentration, it is difficult to recover valuable metals through hydrometallurgical processes or by direct recirculation of the dust in a smelting furnace. Thus, the development of pyrometallurgical processes aimed at reducing the concentration of arsenic in the dust (<0.5 wt%) is the main objective of this study, giving particular attention to the production of a suitable material to be recirculated in operations of copper smelting. The work provides a detailed characterization of the dust including the Quantitative Evaluation of Minerals by Scanning Electron Microscopy (QEMSCAN), Scanning Electron Microscope-Energy Dispersive X-ray Analysis (SEM/EDS), X-Ray Diffraction (XRD), the elemental chemical analysis using Atomic Adsorption (AAS), and X-Ray Fluorescence (X-RF). By considering that arsenic volatilization requires a process of sulfidation-decomposition-oxidation, this work seeks to explore the roasting of mixtures of copper concentrate/dust, sulfur/dust, and pyrrhotite/dust. By the elemental chemical analysis of the mixture after and before the roasting process, the degree of arsenic volatilization was determined. The results indicated the effects of parameters such as roasting temperature, gas flow, gas composition, and the ratio of mixtures (concentrate/dust, sulfur/dust, or pyrrhotite/dust) on the volatilization of arsenic. According to the findings, the concentration of arsenic in the roasted Flash Smelting dust can be reduced to a relatively low level (<0.5 wt%), which allows its recirculation into an smelting process.

Investigation on the Sediment Characteristics of the Electrostatic Cyclonic Precipitator

In order to find out the relationship between the sediment characteristics and collecting efficiency of the electrostatic cyclonic precipitator, an online study for the sediment characteristics of electrostatic cyclonic precipitator had been done with Kompton back scatter method, with the collecting efficiency tested at the same time. And the relationship between the sediment characteristics and the collecting efficiency was gotten. The sediment thickness increased with time extended and the concentration increased when the inlet velocity was fixed. The collecting efficiency increased with the inlet velocity increased, but dropped with the concentration increased. When the concentration and inlet velocity were fixed, the collecting efficiency drop a little with the increase of sediment thickness. The sediment would decrease the corona current in the collecting filed, which would make the electrostatic effect fall, then made the collecting efficiency drop a little.

Application of High-Voltage Power Supply on Electrostatic Precipitator

This article firstly describes the main technical parameters and performance of the high power supply of electrostatic precipitator, and then describes the structure, principle and characteristic of power supply of electrostatic precipitator, and finally analyses the common faults of power supply of electrostatic precipitator in the operation and puts forward the methods of dealing with breakdown. Operation results show that the system is stable and reliable, and overall performance and the efficiency of dust control have been improved significantly. The scheme has been well applied in the field of environmental protection and dust removal.

Comparison of methods for vibration analysis of electrostatic precipitators

The paper presents two methods for the formulation of free vibration analysis of collecting electrodes of precipitators.The first,called the hybrid finite element method, combines the finit element method used for calculations of spring deformations with the rigid finite element method used to reflect mass and geometrical features,which is called the hybrid finite element method.As a result,a model with a diagonal mass matrix is obtained.Due to a specific geometry of the electrodes,which are long plates of complicated shapes,the second method proposed is the strip method which is a semi-analytical method.The strip method allows us to formulate the equations of motion with a considerably smaller number of generalized coordinates.Results of numerical calculations obtained by both methods are compared with those obtained using commercial software like ANSYS and ABAQUS.Good compatibility of results is achieved.

Impact of Urbanization on Low-Temperature Precipitation in Beijing during 1960–2008

Daily precipitation and temperature records at 13 stations for the period 1960-2008 were analyzed to identify climatic change and possible effects of urbanization on low-temperature precipitation [LTP, precipitation of ≥ 0.1 mm d^-1 occurring under a daily minimum temperature （Tmin） of ≤ 0℃] in the greater Beijing region （B JR）, where a rapid process of urbaniza tion has taken place over the last few decades. The paper provides a climatological overview of LTP in B JR. LTP contributes 61.7% to the total amount of precipitation in B JR in the cold season （November-March）. There is a slight increasing trend [1.22 mm （10 yr）^-1] in the amount of total precipitation for the cold season during 1960-2008. In contrast, the amount of LTP decreases by 0.6 mm （10 yr）^-1. The warming rate of Train in B JR is 0.66℃ （10 yr）^-1. Correspondingly, the frequency of LTP decreases with increasing Tmin by -0.67 times per ℃. The seasonal frequency and amount of LTP in southeast B JR （mostly urban sites） are 17%-20% less than those in the northwestern （rural and montane sites）. The intensity of LTP for the urban sites and northeastern B JR exhibited significant enhancing trends [0.18 and 0.15 mm d^- 1 （10 yr）^- 1, respectively]. The frequency of slight LTP （〈0.2 mm d^-1） significantly decreased throughout B JR [by about -15.74% （10 yr）^-1 in the urban area and northeast B JR], while the contribution of the two heaviest LTP events to total LTP amount significantly increased by 3.2% （10 yr） ^-1.

Mechanism Research on PM2.5 Charging, Precipitation in High Electrostatic Field

In this project, some charged characteristics, and analysis of precipitated PM2.5 in high electrostatic field were calculated based on theories and experiments. The connection between the charge amount and the additional electric field intensity caused by the wet flexible collectors was studied to reveal the mechanism of charging enhancement of PM2.5 on flexible collectors. Some explanation about the wet ability of collectors and the current density enhancing the precipitation process was proposed in this project. Simultaneously, the results shows that both gas treatment time and applied voltage have an important influence on particle collection, and the minor factor was initial concentration.

双区与单区电除尘器内部流场电场对比研究

电除尘器内部电场和流场特性对除尘器的除尘性能有重要影响。该文使用Fluent模拟软件对相同比尘集面积的单区与双区电除尘器进行数值模拟,对比单区和双区电除尘器的电场强度、电流密度分布和不同电场风速下的内部流场变化,以此分析电除尘器对不同粒径颗粒除尘效率的影响和双区电除尘器能够高效率捕集高比电阻粉尘的原因。结果表明,双区电除尘器荷电区电流密度与电场强度和单区电除尘器分布相似,单区电除尘器的平均板电流密度为0.56 mA/m^(2),平均电场强度为2.20 kV/cm,双区电除尘器荷电区的平均板电流密度为0.51 mA/m^(2),平均电场强度为2.40 kV/cm。但双区电除尘器收尘区的电场与流场特性和单区电除尘器差别较大,双区电除尘器收尘区平均板电流密度为0.0036 mA/m^(2),只为单区电除尘器的0.6%,而平均电场强度为4.0 kV/cm,是单区电除尘器场强的1.8倍,且双区电除尘收尘区流场分布较均匀,受离子风影响小。收尘区内低电流密度,高电场强度,较少的离子风扰动是双区电除尘器有效捕集高比电阻粉尘,避免反电晕发生的主要原因。

基于COMSOL 的不同温度气体脉冲放电特性的数值模拟研究

为了研究基于脉冲电源的线管式静电除尘器的放电特性,使用COMSOL软件建立了空气放电模型。在实验参数下模拟了空气放电,模拟结果与实验数据结果吻合较好。探究峰值电压、电极尺寸及气体温度等因素对放电特性的影响。结果表明,随着峰值电压及温度的升高,放电空间电子及离子密度逐渐增大,且高密度区域范围逐渐增大。电极半径尺寸越小,放电效果越好,放电空间电子及离子密度越高。研究了不同温度下反应速率与热电子发射对气体放电的影响,发现温度较高时热电子发射对放电具有显著的增强效果,大大提高了放电区域的电子及离子密度。

黄磷生产中固废处置与资源化利用研究进展

黄磷是我国国民经济的重要支柱产业,属于国家战略资源。随着我国磷化工行业的飞速发展,黄磷产能跃居世界首位。我国黄磷生产规模庞大,但生产工艺竞争力不强、磷资源利用率较低。生产过程中磷副产物成分复杂、生成量大。其中黄磷炉渣、泥磷和电除尘灰是主要的固体废弃物,多数企业处理含磷固废时常采用堆积放置的方法,这不仅产生污染,还造成资源极大的浪费。在“双碳”背景下,我国黄磷工业节能减排、绿色发展面临着新的、更大的挑战。本文综述了现阶段对于黄磷工业中产生的黄磷炉渣、泥磷和电除尘灰等固体废物资源化处置的技术和制磷生产中固废的处置现状,指出了未来资源化利用的发展方向,为实现黄磷行业的绿色生产、资源利用、节能减排提供参考。

窄间距静电除尘分离细颗粒物综合实验设计

细颗粒物分离是环境工程教学的核心内容,为提升“大气污染控制工程实验”、“环境工程综合实验”等课程“两性一度”教学水平,将室内细颗粒物污染特征及其分离技术等公众关注的热点问题引入实验教学。利用自制窄间距静电教学实验系统,模拟发生不同粒径范围、数目浓度和质量浓度的细颗粒物,通过改变静电分离组件、电极配置、电场风速和供电电压等参数,综合评价窄间距静电除尘实验系统分离细颗粒物的效能,实验内容可拓展到餐饮油烟特征细颗粒物等应用场景。实验不仅提升学生实验操作能力,也通过不同难度等级的实验设置,分层次培养学生高阶性思维,激发学生实验热情,对提高本科生培养质量具有重要意义。

双阴极静电除尘器仿真优化模型与试验验证

为改善线板式静电除尘器对PM_(2.5)细颗粒物存在穿透窗口问题,提高其对超细颗粒物的收集效率,本文采用有限元法分析和模拟双阴极静电除尘器内流场、电场、颗粒荷电及颗粒运动等物理场的耦合过程;使用泊松方程、偏微分方程描述电场,利用标准k-ε湍流模型描述流场,采用Lawless模型描述颗粒荷电方式,并用拉格朗日模型描述颗粒运动状态;在Comsol仿真平台上搭建双阴极除尘器模型,进行双阴极提高静电除尘效率研究。数值模拟结果表明:在同一放电极电压下,随着颗粒入射速度的升高,电致离子风对流场里的颗粒总体速度影响逐渐变弱,这使得流场里的颗粒的速度差异变小;随着辅助阴极电压的上升,不同入口速度的各种粒子到达集尘板所需的水平位移逐渐变少;当粒子入射速度为0.5 m/s时,对比无辅助极板增加辅助阴极电压至-25 kV,可以使0.1~1.0μm细颗粒物的集尘效率达到98.5%;当粒子入射速度为0.5 m/s时,在同一辅助阴极电压下,放电极电压从-20 kV增加到-25 kV,可提高0.1~1.0μm细颗粒物的集尘效率达25%。

HAMON电除尘器故障分析及应对措施

HAMON电除尘器可用于处理催化裂化烟气中的催化剂粉尘。由于催化裂化装置四年一修,电除尘器不能随时停运检修,因此针对HAMON电除尘器的运行情况进行研究,对于保障电除尘器及催化裂化装置的长周期稳定运行具有重要意义。在运行过程中,电除尘器出现电流和电压降低的问题。对故障原因进行分析,并在电除尘器停运后进行检查,发现:腐蚀泄漏导致电除尘器内部烟气湿度大。制定了检查、检修项目,更换了配件,同时结合冷态试验结果,调整了电除尘器的电流、电压、振打周期和振打力度。检修开工后,电除尘器入口粉尘质量浓度53.3 mg/m^(3),出口粉尘质量浓度4.8 mg/m^(3),远低于设计值(30 mg/m^(3))。检修开工至今超过2 a,电除尘器运行平稳,未出现任何故障,实现了长周期稳定运行。

电除尘节能控制系统在烧结厂的应用

本文结合烧结厂15#机头电除尘控制系统改造,收集了相关运行数据,对节能降耗进行了研究分析,在相同生产状态下节电率达到58%,粉尘浓度降低了48%,改造效果明显,为同类型的电除尘节能改造提供参考。

对改性飞灰烟道循环喷射脱硫脱NH_(3)的研究

本文设计了飞灰循环改性系统及烟道喷射系统,由喷射装置将其均匀喷入烟道中,使改性飞灰与烟气中的酸性气体或碱性气体发生反应,避免对后续除尘器等设备的腐蚀。实验表明,改性飞灰对烟气中的NH_(3)、SO_(2)有很好的吸附效果。

输煤系统湿式电除尘器阴极线放电特性数值模拟

输煤环境中漂浮着大量微细粉尘,湿式电除尘器是去除10μm以下颗粒物的重要手段。本文建立了描述电除尘器放电(电势、电荷密度、电场强度等)、流场、粉尘运动的数学模型,数值模拟结果与Penney等人实验结果一致性较好。针对长×宽=650 mm×150 mm、3根阴极线直径为5 mm的放电系统进行了流场、放电及粉尘运动的数值模拟分析,通过所建立的数学模型,获得了较好分布的电势、电荷密度和电场强度,能够有效指导电除尘器的设计优化以提高除尘效率。

基于烧结机头粉尘特性理论的电除尘器灰斗结块燃烧研究

某钢厂烧结机机头电除尘器除尘灰灰斗发生了结块燃烧现象,影响了机头电除尘器运行。针对烧结机机头电除尘器除尘灰的粉尘特性进行研究,通过检测分析粉尘的含水量、成分、含碳量及粒径分布等,明晰烧结机头电除尘器灰斗结块燃烧原因,并提出基于烧结机头粉尘特性理论的电除尘器灰斗结块燃烧解决措施。研究表明:除尘器灰斗粉尘中水碳成分、碱金属氧化物以及微细粉尘占比较高,且一电场到三电场含量都呈现递增态势,从而导致除尘器灰斗中出现结块燃烧现象。由此提出烧结配料控制湿度6%~8%之间以及电除尘器灰斗增加声波吹灰器的结块燃烧解决措施,可为治理机头电除尘器除尘灰灰斗结块燃烧提供借鉴。

井下皮带机转运点除尘方案探析

基于井下皮带机转运点除尘方案,介绍一种转运点静电除尘装置设计结构。此静电除尘装置主要包括收尘电极、电晕线、振打清灰装置、高压电源、风机等结构,采用有限元仿真模拟方法,从除尘装置内流场、除尘装置内颗粒物轨迹以及皮带速度对气流的影响三个角度初步验证静电除尘装置的可行性,再采用工业性试验进一步确认静电除尘装置的应用价值,证明此除尘装置具有较好的皮带机转运点除尘效果。

DCS在电除尘系统自动控制的应用研究

传统的电除尘器自动控制系统采用可编程逻辑控制器(PLC)控制,其逻辑复杂、可读性差、可维护性低。PLC系统无法与主控系统完成一体化,导致工艺上的割裂,额外地增加了运维成本。本文提出了一种基于分散控制系统(DCS)的电除尘器自动控制方案。