Fine particles can suspend in the air over a long period of time, which leads to fog and haze. As one of the main sources of fine particle emission, coal-fired units usually apply electrostatic precipitator (ESP) and wet flue gas desulfurization (WFGD) system to control particle emission. According to the coal and fly ash properties of a 600 MW coal-fired unit, the influence of flue gas conditioning (FGC) on the performance of ESP was experimentally studied, and the removal mechanism of fine particles was also analyzed. Moreover, the particle samples at inlet and outlet of the WFGD system were collected to measure the mass concentration of particles with different diameters. The results show that, the ash particle concentration at outlet of the ESP applying dual FGC was 18 mg/m3, which was 55 mg/m3 lower than that not using the FGC. The fly ash resistivity decreased to 1.23×1010Ω·cm after injecting 42.86 mg/m3 SO3 at the ESP inlet, which was in the effective operating range. After the flue gas passed through the WFGD system, the particle concentration dropped from 18 mg/m3 to 4.2 mg/m3 and the particle removal efficiency was 76.67%. However, the fine particle concentration increased by 0.84 mg/m3, which were mainly fine particles (generating during WFGD process, CaSO4·2H2O) with diameter smaller than 1 μm.%细颗粒物可长期悬浮于大气中造成雾霾,燃煤机组作为细颗粒物主要排放源之一,可通过安装静电除尘器(ESP)和湿法烟气脱硫(WFGD)装置控制烟气颗粒物排放质量浓度.本文基于某600 MW燃煤机组的煤质和飞灰特性,实验研究了烟气调质(FGC)对ESP除尘性能的影响,并分析了其对颗粒物的脱除机理;同时,采集了WFGD系统出入口烟气颗粒物样品,测量总颗粒物和各粒径段颗粒物的质量浓度.结果表明:采用双重FGC时,ESP出口烟气灰颗粒质量浓度为18 mg/m3,较未采用FGC时减少55 mg/m3;在ESP入口烟道喷入42.86 mg/m3的SO3后,飞灰比电阻降为1.23×1010Ω·cm,此时比电阻降至ESP的有效工作范围内,经WFGD后烟气总颗粒物质量浓度由18 mg/m3降至4.2 mg/m3,除尘效率为76.67%,而细颗粒物质量浓度由1.87 mg/m3增至2.71 mg/m3,增加了0.84 mg/m3,这源于WFGD过程生成的粒径小于1μm的细颗粒物,其主要成分为CaSO4·2H2O.
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