氨法烟气脱硫装置气溶胶排放特性研究

Emission characteristics of aerosol from ammonia-based wet flue gas desulfurization

结合扬子热电厂二期玛苏莱氨法脱硫工艺运行参数,采用模拟试验装置考察了氨法烟气脱硫工艺的气溶胶排放特性,并对该电厂气溶胶颗粒的来源进行了分析。结果表明:氨法烟气脱硫过程中会产生大量气溶胶颗粒,从数浓度角度而言,主要属亚微米级微粒,但依据质量浓度分布,粒径呈双峰分布,以微米级及大于10μm的颗粒物为主;同时,脱硫前后颗粒物物性发生显著变化,脱硫净烟气中颗粒多呈规则的晶体结构,含长方体、棱柱体等晶习,S、O元素含量显著增加,主要物相成分为(NH4)2SO4;由烟气带出的雾滴经蒸发析出固体微粒是该电厂气溶胶的重要来源。

The emission characteristics of aerosols were investigated experimentally during the ammonia-based wet flue gas desulfurization(WFGD)process,according to the practical operation condition of Marsulex ammonia-based desulfurization process of Yangzi Thermal Power Plant.The electrical low pressure impactor(ELPI),scanning electron microscopy(SEM)and XRD were employed to analyze the aerosol particle size distribution and concentration,morphologies and compositions before and after the desulfurization.The results showed that,agreat amount of aerosol particles were formed during the ammonia-based desulfurization process.A large number of these particles were sub-critical particulate matters,and these aerosol particles of which the mass concentration appeared a bimodal distribution were mainly micro-size or larger than 10μm.Moreover,after the desulfurization,the physical properties of the particles changed significantly.These particles had the smooth surface and regular crystal structure,including cuboid and prismoid crystal habits.Sulfur and oxygen content in these particles increased obviously,and main compound in the particles was ammonium sulfate((NH4)2SO4).The solid fine particles generated by evaporation of droplets brought out by flue gas were the major source of aerosol emitted from the Yangzi Thermal Power Plant.