脱硫废水液滴蒸发过程中氯迁移转化特性

Migration and Transformation Characteristics of Chlorine During Desulfurization Wastewater Droplet Evaporation

为探究脱硫废水旁路热烟气蒸发技术中氯的释放特性,基于单液滴蒸发实验研究了温度、pH、金属阳离子对脱硫废水液滴蒸发过程中氯迁移转化特性的影响,对比不同废水之间氯释放特性的差异。结果表明:氯离子释放存在3个阶段,即自由水蒸发阶段、壳层不稳定阶段和氯盐热分解阶段,气态HCl的释放主要发生在壳层不稳定阶段;温度升高会促进氯的挥发,尤其是在壳层不稳定阶段,温度升高会导致显著的氯损失;当pH从3增加至9,氯从溶液中挥发进入气相的比例由42.50%降低至25.60%;金属阳离子对氯释放的促进作用大小为Mg^(2+)>Ca^(2+)>Na^(+),含氯结晶盐尤其是MgCl_(2)·6H_(2)O热分解产生的HCl是气相氯元素的重要来源。

To investigate chlorine release characteristics in desulfurization wastewater bypass hot flue gas evaporation technology,the effects of temperature,pH and metal cations on chloride migration and transformation characteristics during desulfurization wastewater droplet evaporation were studied based on single droplet evaporation experiment.The difference of chlorine release characteristics among different wastewater was compared.Results show that,there are three release stages of chlorine ion,including free water evaporation stage,shell instability stage and chloride pyrolysis stage,and the release of gaseous HCl predominantly occurs in shell instability stage.The increase of temperature promotes the volatilization of chlorine.Especially in shell instability stage,the increase of temperature leads to significant chlorine loss.As the pH increases from 3 to 9,the proportion of chlorine evaporating from solution to gas phase decreases from 42.5%to 25.6%.The promoting effect of metal cations on the chlorine release is Mg^(2+)>Ca^(2+)>Na^(+),and the HCl produced by the pyrolysis of chlorine-containing crystalline salts,especially MgCl_(2)·6H_(2)O,is an essential source of gas phase chlorine.