ESP内气流均匀性和除尘效率的数值模拟

Numerical simulation of uniformity of flow and dust collection efficiency of ESP

基于计算流体力学,以相对均方根(RMS)值为气流均匀性的评判标准,应用FLUENT软件模拟了粉尘粒径、烟气流速、电晕极电压及烟气含尘浓度对静电除尘器的除尘效率和细微尘涡流现象的影响。研究表明,随着粉尘粒径和烟气流速的增大,颗粒合速度增大,RMS值大幅降低,涡流趋势减弱;而随着粒径增大,颗粒的驱进速度增大,除尘效率提高,但烟气流速增加,增大了颗粒的轴向速度,使得除尘效率降低;随着电晕极电压的升高,RMS值增大,涡流趋势增强,但电晕极电压升高,带电颗粒的电场力大幅增加,除尘效率提高。当含尘浓度小于5 g/m3时,随着含尘浓度的增加,由于"电风"的作用使得除尘效率和RMS值均增大,涡流趋势增强;但当含尘浓度超过5 g/m3时,随着含尘浓度的增加,"电风"逐步减弱,RMS值和除尘效率开始下降,涡流趋势减弱。

Based on computational fluid dynamics and FLUENT software platform,the relative root mean square（RMS）value was applied as the criterion for judging the uniformity of air flow,and the effects of particle diameter,lue gas velocity,corona electrode voltage,concentration of fine dust on the vortex phenomenon and dust collection efficiency in electrostatic precipitator were simulated in this study. From the results,with the increase of particle diameter and flue gas velocity,the resultant velocity of particles can be increased and the RMS value is cut down greatly,so the tendency to form vortex is weakened. On the other hand,with the increase of particle diameter,the driving velocity of particles can be increased and the dust collection efficiency is improved. But when the flue gas flow rate is increased,the axial velocity can be increased and the dust collection efficiency is reduced. It is found that the larger of corona voltage,the RMS value is bigger and the tendency to form vortex is enhanced. But when the corona voltage is increased,the electric field force of particle is increased significantly,so the dust collection efficiency is improved. If the dust concentration is less than 5 g/m^3,with the increase of dust concentration,as a result of the action of ＂electric wind＂,the dust collection efficiency will be increased and the RMS value will be increased,the vortex will also be strengthened. If the dust concentration exceeds 5 g/m^3,with the increase of dust concentration,the action of ＂electric wind＂ will be depressed gradually,the RMS value will be cut down and the dust collection efficiency will decline and the vortex will be weakened.