ABSTRACT

Along with the increasingly stringent dust emission concentration standards for the thermal power plants and the challenge of market competition, wet electrostatic precipitators (ESPs) have been widely used as terminal equipment for the flue gas treatment. The wet ESPs pilot test platform using the modified carbon steel collectors with hydrophilic properties was established in this paper and the experimental research on PM_2.5 removal characteristics were carried out. The mechanism of the particles removal efficiency enhancement by water film on the surface of modified collectors was studied. The effect of gas temperature, residence time, working voltage, inlet concentration, and flushing water flowrate on the particles removal efficiency was investigated. The results indicated that the fibrous layer over the surface of the modified collectors could reduce the effect of the airflow recoil and the electromigration resistance of particles. The surface of the modified collectors could also maintain a uniform and stable water film with a lower amount of water consumption. The water film could restrain the back corona and the re-entrainment of dust. And the evaporation of water film increased the humidity of the flue gas, meanwhile, the particles charge capacity and electromigration velocity increased. Those all could improve the particles removal efficiency. The particles removal efficiency increased with the increase of the flue gas residence time and the applied voltage, but the particles removal efficiency improved less with the increase of the particles inlet concentration and flushing water flow rate after maintaining uniform and stable water film. The modified rigid collector provided high removal efficiency for particles with diameters of 0.04～0.48 μm under lower energy and water consumption.

Implications: The wet electrostatic precipitators (ESPs) have been widely used as terminal equipment of the flue gas treatment to purify the flue gas deeply. The surface of the modified carbon steel collectors with hydrophilic properties could maintain a uniform and stable water film with a lower amount of water consumption. The evaporation of water film improved the particle charge capacity and electromigration velocity. The wet ESPs using the modified rigid collector exhibited significantly higher removal efficiency of particles than using the conventional rigid collector especially to the particles with diameter of 0.04～0.48 μm.

摘要

随着火电厂粉尘排放浓度标准的日益严格和市场竞争的挑战，湿式静电除尘器（ESP）已被广泛用作烟气处理的终端设备。本文建立了使用具有亲水性能的改性碳钢集热器的湿式静电除尘器中试平台，并对 PM _{2.5 进行}了实验研究。进行了去除特性。研究了改性集电体表面水膜提高颗粒去除效率的机理。研究了气体温度、停留时间、工作电压、入口浓度和冲洗水流量对颗粒去除效率的影响。结果表明，改性集电体表面的纤维层可以降低气流反冲的影响和颗粒的电迁移阻力。改性后的集电体表面也能以较低的耗水量保持均匀稳定的水膜。水膜可以抑制背电晕和灰尘的再夹带。并且水膜的蒸发增加了烟气的湿度，同时，粒子电荷容量和电迁移速度增加。这些都可以提高颗粒去除效率。颗粒去除效率随着烟气停留时间和外加电压的增加而增加，但在保持均匀稳定的水膜后，颗粒去除效率随着颗粒入口浓度和冲洗水流量的增加而提高。改进的刚性收集器在较低的能耗和水消耗下对直径为0.04～0.48 μm的颗粒具有较高的去除效率。但在保持均匀稳定的水膜后，随着颗粒入口浓度和冲洗水流量的增加，颗粒去除效率的提高幅度较小。改进的刚性收集器在较低的能耗和水消耗下对直径为0.04～0.48 μm的颗粒具有较高的去除效率。但在保持均匀稳定的水膜后，随着颗粒入口浓度和冲洗水流量的增加，颗粒去除效率的提高幅度较小。改进的刚性收集器在较低的能耗和水消耗下对直径为0.04～0.48 μm的颗粒具有较高的去除效率。

启示: 湿式静电除尘器（ESP）已广泛用作烟气处理的终端设备，对烟气进行深度净化。具有亲水性能的改性碳钢集热器表面能以较低的耗水量保持均匀稳定的水膜。水膜的蒸发提高了粒子的电荷容量和电迁移速度。使用改性刚性收集器的湿式静电除尘器对颗粒的去除效率明显高于传统刚性收集器，尤其是对直径为0.04～0.48 μm的颗粒。