应用水汽相变促进湿法脱硫净烟气中PM_(2.5)和SO_3酸雾脱除的研究

在石灰石-石膏法脱硫净烟气中分别采用添加适量蒸汽和湿空气方式建立PM_(2.5)和SO_3酸雾凝结长大所需的过饱和水汽环境,在测试分析湿法脱硫净烟气中PM_(2.5)及SO_3酸雾物性的基础上,考察了蒸汽及湿空气添加量、脱硫净烟气温度等的影响。结果表明,湿法脱硫净烟气中PM2.5除含有燃煤飞灰外,含Ca SO_4、Ca SO_3及未反应的Ca CO_3等组分;由于SO_3酸雾基本处于亚微米级粒径范围,湿法烟气脱硫(WFGD)系统对SO_3酸雾的脱除率仅为35%-55%;添加适量蒸汽及湿空气方式均可促进湿法脱硫净烟气中PM_(2.5)和SO_3酸雾脱除,最终排放浓度随蒸汽或湿空气添加量的增加而降低,其中,添加蒸汽方式适合于脱硫净烟气温度较低(≤50-55℃)的场合,在脱硫净烟气温度较高(≥55-60℃)时,利用添加湿空气方式替代添加蒸汽更具技术经济优势。

Improvement in removal of fine particles and SO3 acid mist from desulfurized flue gas with heterogeneous condensation

The supersaturated water vapor environment for condensational growth of fine particles (PM_2.5) and SO₃ acid mist was achieved by adding water vapor or humid air into the limestone-gypsum desulfurized flue gas. The influences of the addition amount of water vapor and humid air as well as the desulfurized flue gas temperature were analyzed based on the property analysis of PM_2.5 and SO₃ acid mist. The results show that except for coal-fired ash, the desulfurized flue gas also includes CaSO₄, CaSO₃ and unreacted CaCO₃ in PM_2.5. The removal efficiency of SO₃ acid mist is 35%-55% merely by wet flue gas desulfurization (WFGD) system because SO₃ acid mist is mostly submicron particles. PM_2.5 and SO₃ acid mist can be removed effectively by adding either water vapor or humid air, and the emission concentration decreases with increasing the amount of water vapor or humid air. Moreover, it is found that it is better to add water vapor to establish the supersaturated water vapor environment for lower temperature desulfurized flue gas (≤50-55 ℃), while it is more appropriate to add humid air for higher temperature desulfurized flue gas(≥55-60℃).