利用蒸汽相变脱除湿式氨法脱硫中形成的气溶胶微粒

Removal of Fine Aerosol Particles Formed in Wet Ammonia Flue Gas Desulfurization Process by Heterogeneous Condensation

通过对湿式氨法烟气脱硫过程中细颗粒的浓度分布、形态及组成变化特性的测试分析,探讨了氨法脱硫中气溶胶的形成机理.利用蒸汽相变原理,采用添加适量蒸汽的方法,进行了细颗粒的凝结长大脱除试验.结果表明：氨水挥发出的气态NH3与烟气中的SO2发生气相反应是气溶胶形成的主要原因;（NH4）2SO3是气溶胶的主要组分,气溶胶微粒粒径集中在0.07～0.70μm内,氨法脱硫系统对其难以有效脱除;与燃煤飞灰颗粒相比,脱硫形成的气溶胶微粒在较低的过饱和度下就能发生凝结长大,应用蒸汽相变技术可有效脱除湿式氨法脱硫中形成的气溶胶微粒.

The formation mechanism of aerosol in wet ammonia flue gas desulfurization（FGD） was studied through measurement and analysis of particles concentration distribution, shapes and composition change features during the desulfurization process. And based on the principle of heterogeneous condensation, an appropriate amount of steam was added to test the removal effect of the fine particles in an condensation enlargement status. Results show that the aerosol formation is mainly caused by the gaseous reaction between NH3 vapor of liquid ammonia and SO2 in the flue gas. The aerosol particles, mainly consisting of （NH4）2SO3, with sizes lying between 0. 07μm and 0. 70 μm, are hard to be effectively removed in the ammonia desulfurization system. Comparing with fly ash particles of coal combustion, the fine aerosol particles formed in desulfurization could be enlarged at a lower supersaturation degree. Applying heterogeneous condensation technology, the fine aerosol particles formed in wet ammonia FGD process could be effectively removed.