蒸汽相变与撞击流耦合促进细颗粒物脱除

Improving removal of fine particles by coupling heterogeneous condensation with impinging streams

针对石灰石/石膏法湿式烟气脱硫(WFGD)工艺,考察了WFGD系统对烟气温湿度和细颗粒形貌与元素组成的影响,并分析了相变室中过饱和水汽环境的形成特性;在此基础上,采用蒸汽相变和撞击流耦合的方法,实验研究了撞击流相变室中应用蒸汽相变促进细颗粒物脱除的效果,并与普通蒸汽相变室进行了比较.结果表明:细颗粒经石灰石/石膏法脱硫后形貌特征与元素组成均发生明显变化,WFGD系统出口脱硫净烟气接近饱和甚至达到过饱和状态,仅添加少量蒸汽就可建立水汽在细颗粒表面核化凝结所需的过饱和环境;采用蒸汽相变和撞击流耦合技术可以显著促进湿法脱硫净烟气中细颗粒物的脱除,在蒸汽添加量为0.04 kg/m3时,数浓度脱除率可由普通相变室的34.1%增至66.1%;细颗粒脱除效率随烟气撞击流速增大而提高.

The influence of wet limestone/gypsum processes flue gas desulfurization system on fine particles morphologies,element composition and flue gas temperature and humidity was analyzed,and the super-saturation degree of flue gas in condensational growth chamber was calculated.On the basis of this,the removal of fine particles from wet flue gas desulfurization（WFGD）system was investigated experimentally by coupling impinging streams with heterogeneous condensational growth technology,and the results were compared with those of ordinary horizontal type heterogeneous condensational growth chamber.It is shown that fine particles morphology and element composition are changed obviously via wet limestone/gypsum desulfurization system.The relative humidity of flue gas approaches saturation or even super-saturation at WFGD system outlet.Only adding a small amount of steam can form super-saturation environment required by nucleation condensation.Fine particles can be removed more effectively by adopting the coupled impinging streams and heterogeneous condensation technology.The impinging streams heterogeneous condensational growth chamber has better performance in removal particles than ordinary horizontal type heterogeneous condensational growth chamber,for example,when the addition amount of steam is 0.04 kg/m3,the number concentration removal efficiency increases from 34.1% to 66.1%.Increasing flue gas speed leads to higher removal efficiency.