耦合电袋除尘器颗粒物群平衡模拟及协同脱除机理研究

Coupled Electrostatic Precipitator and Bags is a new and efficient dust removal technology with important application prospects. However, the structure of Coupled Electrostatic Precipitator and Bags is complex, the mechanism of dust migration and collection is not clear, and the design cost by experiment is high. This project adopts the measurements such as isokinetic sampling-weighing, the electrical low pressure impactor (ELPI), the scanning electron microscopy (SEM) analysis and etc., to measure the surface deposition appearance of filter material, pressure drop through filtration, system energy consumption, dust concentration and particle size distribution at the outlet, collection efficiency, etc. By adjusting the operation parameters of power supply in the electrostatic precipitation, the influence of synergistic removal by electrostatic precipitation and bags on filtration pressure drop and filtration efficiency would be studied, which would provide reliable data for macro-theoretical research. The population balance model would be established based on CFD simulation, particle dynamics theory and population balance theory. The particle dynamics in the coupled Electrostatic Precipitator and Bags would be simulated by means of the population balance modelling. The spatial distribution in the electrostatic precipitation area and bags area, and the surface distribution deposited on the collection ground and on the fiber would be analyzed. Combined the experimental data, a software for solving the problems of particle dynamics in Coupled Electrostatic Precipitator and Bags would be developed. The design method of the structure and operation parameters for Coupled Electrostatic Precipitator and Bags would be established to meet the requirements of high dust removal efficiency, low energy consumption and compact structure.

耦合电袋除尘器是一种具有重要应用前景的新型高效除尘技术，但耦合电袋除尘器内结构复杂，粉尘迁移、捕集机理尚不明确，实验设计成本高。本项目采用等速采样-称重法、ELPI分级在线测试法，SEM等测量方法，测量滤料表面沉积形貌、过滤压降、系统能耗、出口粉尘浓度和粒径分布、粉尘脱除效率等，调节电除尘区电源运行参数，研究电除尘区和袋除尘区协同作用对过滤压降和过滤效率的影响规律，并为宏观理论研究提供可靠数据；理论上，拟结合CFD模拟、颗粒动力学理论和群平衡理论，建立复杂三维多场作用下的颗粒群平衡模型，研究耦合电袋除尘器内的颗粒动力学演化过程，观测电除尘区和袋除尘区颗粒的空间分布规律，以及收尘极板和滤袋表面的粉尘沉积规律，结合实验测量规律，开发耦合电袋除尘器内颗粒动力学求解软件，建立满足高粉尘脱除效率、低能耗、结构紧凑要求的耦合电袋除尘器电除尘区与袋除尘区结构匹配和运行参数设计方法。

耦合电袋除尘器有机结合传统静电除尘器和布袋除尘器，能够高效脱除烟气中的颗粒物，但其内部结构复杂，粉尘迁移、捕集机理尚不明确，实验设计成本高。本项目以此为背景通过实验、数值计算相结合的方法研究了耦合电袋除尘器内的气固两相流动。搭建了耦合电袋除尘器实验平台，研究了结构、电压、风速、滤料等对除尘器性能的影响，揭示了电除尘区和袋除尘区的结构和运行工况匹配优化区间；基于颗粒动力学理论和群平衡理论，结合CFD模拟（CFD-PBM），建立并求解了耦合颗粒荷电、迁移、冷凝、团聚等模型的群平衡方程，开发了复杂三维多场作用下的颗粒沉积特性分析软件，明确了颗粒物和SO3的高效协同脱除机制；定量分析了耦合电袋除尘器内颗粒物的速度、浓度分布规律，揭示了颗粒物的三维沉积特性；通过改进现有静电除尘器和静电增强过滤除尘效率模型，建立了耦合电袋除尘器效率计算模型。研究结果表明：硫酸液滴沉积量随粒径增大先增加后减小，大约60–80% 的硫酸沉积在1 μm附近，极大地提高了此范围内颗粒物的介电常数和驱进速度，降低了PM2.5和SO3的排放浓度；前区电场、后区AHPC结构的耦合电袋除尘器除尘性能最优且运行参数范围较宽。大粒径颗粒速度主要受电场力和重力影响，速度分布与气相流场差异较大，小粒径颗粒随流性较好，速度分布与流场分布趋于一致；一级收尘极板、二级收尘极板、布袋和底面对总除尘效率的贡献分别是66%、12%、9%和12%，一级电除尘区主要捕集大粒径颗粒，颗粒物沉积量的分布主要取决于电场分布，二级AHPC区主要捕集小粒径颗粒，颗粒物沉积量的分布主要取决于流场分布。研究成果为耦合电袋除尘器的设计和运行提供了理论支撑；同时CFD-PBM模型实现了气固两相流动中颗粒物的分布和沉积特性的定量分析，丰富了气固两相流动的研究方法。