电厂湿法脱硫系统对烟气中细颗粒物脱除作用的实验研究

Experimental Study on Removal Effect of Wet Flue Gas Desulfurization System on Fine Particles From a Coal-fired Power Plant

采用Andersen8级撞击器对某300MW燃煤电厂湿法烟气脱硫(wet flue gas desulphurization,WFGD)系统前后的飞灰颗粒物进行采集,获得了烟气中飞灰颗粒物的质量浓度和粒径分布特性。采样工况分别为100%和70%锅炉负荷。使用场发射扫描电镜-能谱分析,X射线荧光分析和电感耦合等离子体-原子发射光谱分析法对颗粒物进行了形貌分析和主、次量元素含量的检测。结果表明,WFGD系统入口飞灰质量粒径呈典型的双峰分布,峰值分别在1和3μm处,颗粒多呈规则球形,PM2.5与PM10质量比为0.434,飞灰总浓度约为85mg/m3标准状态;出口处飞灰质量粒径分布也呈现双峰性,其中细颗粒比例增大,PM2.5与PM10质量比为0.764,细颗粒间相互聚集粘连形成不规则的块状结构,飞灰总浓度在23mg/m3(标准状态)以下,总飞灰的脱除效率为74.5%,分级脱除效率随粒径减小而明显下降。经过WFGD系统后,细颗粒上S和Ca元素含量增大,而Al,Ba,Fe,Mn和Si元素的含量降低。计算表明,WFGD出口烟气中新增的石灰石与石膏颗粒分别占颗粒物质量的47.5%和7.9%。

Fly-ash particles from the inlet and outlet of the wet flue gas desulphurization（WFGD） system in a 300 MW coal-fired power plant were sampled by an Andersen 8-stage impactor and the mass concentrations and size distributions of fly-ash particles in flue gas were obtained. The samplings were developed under 100% and 70% boiler loads. The microstructure, major and minor-element concentrations of particles were measured using field emission scanning electron microscopy/energy dispersive X-ray spectrometry（FESEM- EDS）, X-ray fluorescence（XRF） and inductively coupled plasma - atomic emission spectrometry （ICP-AES）, respectively The results indicate that the mass size distribution of fly-ash particles in the inlet of the WFGD system is typically disturbed bimodally, the peaks are approximate at 1 and 3 μm. And the shape of particles is regular sphericity, the mass ratio of PM2.5 to PM10 is about 0.434. The total mass concentration is about 85 mg/m^3. In the outlet of the WFGD system, the mass size distribution of fly-ash particles is also bimodal. The proportion of fine particles increased, the mass ratio of PM2.5 to PM10 is about 0.764, Some fine particles are conglutinated and formed irregular agglomerate. The total mass concentration is under 23 mg/m^3, the removal efficiency of total particles is 74.5%. The size removal efficiency is decreased observably with the range of particle size decreasing. After the WFGD system, the element concentrations of S and Ca in fine particles are augmented, and the concentrations of Al, Ba, Fe, Mn and Si are decreased oppositely. Fine particles in the outlet of WFGD system consist of about 47.5% limestone and 7.9% gypsum particulate matters.