水膜对静电除尘器内部微细颗粒分布及运动特性的影响研究

Influence of Water Film on the Distribution and Motion Characteristics of Fine Particles in Electrostatic Precipitator

建立了一个静电除尘器微细颗粒分布与运动特性研究平台,通过改造的静电低压撞击器对电除尘器极板有/无水膜状态下的微细颗粒浓度变化进行实时测试,结合静电除尘器内部不同区域微细颗粒的受力分析,研究了水膜对静电除尘器内部颗粒的分布状况、运动轨迹、沉积情况、分级效率及力学行为等的影响。研究表明,水膜对近壁区微细颗粒的力学行为影响显著,均布水膜后近壁区的电场力、热泳力、浓度梯度力均有不同程度的增大,且颗粒与收尘极之间的相互作用转变为气固两相流与水膜之间的扩散过程;有/无水膜状态下静电除尘器内部微细颗粒浓度从中心到壁面均呈现递减的趋势,均布水膜后截面浓度梯度更大（特别是近壁区域）且随着气流的发展近壁面处的低浓度区增大;均布水膜后颗粒沿程浓度的变化主要由粒径为0.1~1μm范围内的颗粒浓度变化引起,浓度降低的最大幅度为30%;有/无水膜状态下微细颗粒物分级脱除效率的曲线形状和变化趋势相似,颗粒粒径为0.3μm时脱除效率最小,当颗粒直径减小或增大时,颗粒脱除效率迅速增大,水膜对小颗粒的脱除效果更显著,较无水膜状态下提高20%左右。

An experimental platform was established to study fine particles distribution and motion characteristics in electrostatic precipitator. The real-time concentrations of fine particles in the ESP with/without water film was tested by the reformed ELPI. The motion characteristics of fine particles such as distribution, trajectory, deposition, classification efficiency and mechanical behavior were analyzed based on the force analysis of fine particles. The results show that the water film has a remarkable influence on the mechanical behavior of fine particles in the near-wall region of the ESP, the electric field force, thermophoretic, concentration gradient force increase respectively, and the interaction between particles and dust collector convert to a diffusion process between gas-solid two phase flow and the water film. Even though with/without water film, both of the concentrations of fine particles show a decreasing trend from the center to the wall in the ESP, the gradient of the cross section increases（especially near-wall region）and the low concentration region near the wall increases with the development of the air flow after water film distributed evenly in the wall. Concentration changes of particles in the range of 0.1-1mm result in a change of that along the way after water film distributed evenly in the wall, and the maximum magnitude of reducing is 30%. Thecurves of the classification removal efficiency of fine particles are similar with/without water film. The removal efficiency is minimal at the particle size of 0.3μm,and when particle size decreased or increased, the particle removal efficiency will increase rapidly. Compared to without water film, the removal efficiency with water film for small particles is increased by 20%.