完美论文网提供代写毕业论文、代写本科论文、代写硕士论文、论文发表及查重服务!QQ:505676555

电话:18796337551
当前位置:完美论文网机械论文 → 文章正文

蜂窝管式电滤装备电场特性及颗粒脱除性能研究

作者:完美论文网  来源:www.wmlunwen.com  发布时间:2019/10/8 9:22:43  

摘要:电滤装备因具有除尘效率高、运行费用低、烟气处理量大等优势被广泛应用在石化、钢铁、火电等工业领域。然而随着大气环境问题的日益严峻和颗粒排放标准的日趋严格,现有电滤装备难以满足细颗粒物的脱除效率的现实需要。因此,为了提高电滤装备的运行稳定性和细颗粒物脱除性能,本文提出了一种新型的芒刺电极+蜂窝管式电滤装备。同时建立电场、气流场和颗粒运动场多场耦合的数学模型,在有限元软件Comsol中添加电场模块(es)、流场模块(spf)和粒子追踪模块(cpt)进行数值研究,分析不同电极形式(芒刺形状、芒刺对称性、芒刺针尖夹角)、气流场、颗粒场对电场放电特性的影响,得出Electrohydrodynamic Flow(EHD流)、颗粒粒径、供电电压及气流速度对颗粒运动特性及除尘效率的影响规律,最终将其与实验结果对比分析。本文的主要研究内容及结论:

(1)蜂窝管内部电流体动力学:分析了蜂窝管内部电场、气流场和颗粒运动场之间复杂的耦合关系。得出如下结论:电场通过EHD流影响气流运动场,通过空间粒子的荷电和电场库仑力作用影响颗粒运动场;气流运动场通过离子流对流影响电场,通过空气曳力作用来影响颗粒运动场;颗粒运动场通过空间电荷(带电粒子)反作用于电场,通过气相—固相的耦合来影响气流运动场。

(2)蜂窝管内部电场放电特性数值模拟:研究了芒刺形状(平端、尖端)、芒刺对称性、芒刺针尖夹角对电晕放电的影响;在最优结构下,研究气流场、颗粒场对电晕放电的影响。得出如下结论:1)相同电压下的最优电极形式为非对称的芒刺尖端,且最优结构参数组合为:芒刺尖端高度3mm,针尖夹角15°,芒刺间距为蜂窝管内径一半。2)在供电电压小于20kV时,细颗粒物的加入使得平均电场强度 增大,但变化不是很大,但随着电压的增大,细颗粒物的加入反而使平均电场强度 减小;在10~50kV电压时,细颗粒物的加入使得场强均匀性 增大,场强最大值 增大,颗粒物理论脱除效率 略增。3)在气流速度为0.5m/s~1m/s时,平均电场强度 和颗粒物理论脱除效率随流速的增大而增大,在气流速度为1m/s~1.5m/s时,平均电场强度 和颗粒物理论脱除效率 随流速的增大而减小;气流速度从0.5m/s增大到1.5m/s时,场强均匀性 逐渐增大,场强最大值 变化不大。

(3)蜂窝管内部颗粒脱除性能数值模拟:研究了EHD流、颗粒粒径、供电电压及气流速度对颗粒运动特性及除尘效率的影响。得出如下结论:气流速度小于1.5m/s时,EHD流对气流场的影响较大,气流速度大于2.5m/s时,EHD流对气流场的影响可忽略;EHD流的存在主要对粒径小于5μm的颗粒脱除效率有影响,而粒径大于5μm的颗粒,EHD流可以忽略。颗粒粒径为1~9μm时,粒径越大,颗粒偏移量越多,除尘效率越大;供电电压为10~50kV时,电压越大,颗粒偏移量越多,除尘效率越大;气流速度为0.5~2.5 m/s时,速度越大,颗粒偏移量越少,除尘效率越低。

(4)蜂窝管内部放电特性与颗粒物脱除性能实验研究:搭建了蜂窝管式电滤装备的放电特性与颗粒物脱除性能实验平台,研究了不同颗粒粒径、气流速度、供电电压对除尘效率的影响,将数值模拟结果与实验对比分析,发现二者存在10%-15%的误差,在可接受的范围内,基本满足工程需要。

Electric filter equipment is widely used inpetrochemical, iron and steel, thermal power and other industrial fieldsbecause of its advantages of high dust removal efficiency, low operating costsand large flue gas handling capacity. With the increasing severity ofatmospheric environmental problems and the stringency of particle emissionstandards, the existing electrofiltration equipment is difficult to meet thepractical needs of the removal efficiency of fine particles. In order toimprove the operation stability and fine particle removal performance of theelectrofiltration equipment, a new type of burr electrode + honeycomb tubeelectrofiltration equipment is proposed in this paper. At the same time, themathematical model of multi-field coupling of electric field, airflow field andparticle motion field is established. The electric field module (es), flowfield module (spf) and particle tracking module (cpt) are added to Comsol ofthe finite element software to carry out numerical research. The effects ofdifferent electrode forms (shape of burr, symmetry of burr, angle between tipof burr), airflow field and particle field on electric field dischargecharacteristics are analyzed. The effects of Electrohydrodynamic Flow (EHD),particle size, power supply voltage and gas velocity on particle motioncharacteristics and dust removal efficiency are discussed and compared withexperimental results. The main contents and conclusions of this paper are asfollows:

(1) Electrohydrodynamics in honeycomb tubes:The complex coupling among electric field, airflow field andparticle field in honeycomb was analyzed. The following conclusions areobtained: The electric field influences the airflow field through EHD flow, andthe particle motion field through the charge of space particles and the Coulombforce of electric field; the airflow field affects the electric field throughion convection, and the particle field through air drag force. The particlefield reacts on the electric field through space charge (charged particles),and influences the airflow field through gas-solid coupling.

(2) Numerical simulation of electric fielddischarge characteristics in honeycomb tube: the effects of burr shape (flatend, tip), symmetry and angle of burr tip on corona discharge were studied;basing on the optimal structure, the effects of airflow field and particlefield on corona discharge are studied. The following conclusions are obtained:1)Under the same voltage, the optimal electrode form is asymmetrical spike tip,and the optimal combination of structural parameters is that the spike tipheight is 3 mm , the spike tip angle is 15 degrees, and the spike spacing isone inner diameter of honeycomb tube. 2)When the powersupply voltage is less than 20 kV, the average electric field intensityincreases with the addition of fine particles, but the change is not very big.However, with the increase of voltage, the average electric field intensitydecreases with the addition of fine particles. When voltage ranges from 10 kVto 50, the field uniformity increases with the addition of fine particles, andthe maximum electric field strength increases, and the theoretical removalefficiency of particles increases slightly. 3) When the air velocity rangesfrom 0.5 m/s to 1 m/s, the average electric field strength and theoreticalremoval efficiency of particulate matter increase with the increase of flowvelocity, while the average electric field strength and theoretical removalefficiency of particulate matter decrease with the increase of flow velocitywhen the air velocity ranges from 1 m/s to 1.5 m/s; when the air velocityincreases from 0.5 m/s to 1.5 m/s, the uniformity of field strength increasesgradually, and the maximum value of field strength does not change much.

关键词:蜂窝管式电滤装备;放电特性;EHD流;颗粒运动轨迹;除尘效率

Honeycomb tubular electric filterequipment; discharge characteristics; EHD flow; particle motion trajectory;dust removal efficiency

联系方式

客服QQ 505676555
客服热线18796337551
网站地址 www.wmlunwen.com
郑重承诺 原创,包修改,包通过!
完美论文网真诚欢迎新老客户的光临与惠顾!