Experimental Research On Removing No/Hg~0 By Surface Dielectric Barrier Discharge

With the increasingly serious situation of air pollution,domestic and foreign research on using non-thermal plasma for pollutant treatment has attracted wide attention,in which dielectric barrier discharge is becoming a focus in the current field of gaseous pollutants removal,due to advantages such as high electron density,uniform discharge,low requirement for power and atmospheric operation.Based on the current research status of dielectric barrier discharge in control of coal-fired flue gas contaminants,a spiral surface dielectric barrier discharge reactor was applied on removal of NO and Hg⁰.In this paper,the performance of two different dielectric barrier discharges was compared,and the effects of power parameters,gas composition and properties,and reactor characteristic on removal of NO and Hg⁰ were investigated.The results indicated that the performance of surface dielectric barrier discharge is significantly better than volumn dielectric barrier discharge in removing NO and Hg⁰.The increase in power and applied voltage can directly promoted the removal of NO and Hg⁰.With the increase of frequency,the removal efficiency of NO and Hg⁰ showed the trend of increasing first and then decreasing,and the optimum frequency decreased with the increase of applied voltage.O₂ with small amount was beneficial to the removal of NO,but O₂ with more than 2%was restraining.However,for Hg⁰ removal,the presence of O₂ was fully demonstrated the role of promotion;The higher initial concentration was,the lower NO removal efficiency was,but Hg⁰ removal efficiency was reverse.The reduction of simulated flue gas residence time and the decrease of reactor cooling water temperature were beneficial to the removal of NO and Hg⁰.On the basis of experiment of removal of NO and Hg⁰ alone,the influence of various gas components on the simultaneous removal of NO and Hg⁰ was also studied.The results showed that the presence of NO had obvious inhibitory effect on the removal of Hg⁰Reversely,the effect of Hg⁰ on the removal rate of NO and the formation rate of NO₂ was almost negligible.CO₂ had a slight inhibition on the removal of NO and Hg⁰.The addition of C₂H₄ could significantly increased the removal rate of NO and Hg⁰,but significantly restrained the removal of Hg⁰,and forms high concentration of CO,while HCl had no side effects.The presence of SO₂ and H₂O resulted in decline of NO and Hg⁰ removal rate,and there was no distinct difference of Hg⁰ removal rate with different moisture content.The removal rate of NO with 68.4%and Hg⁰ with 82.8%were obtained in the mixed system.Under the experimental condition,the energy yield of removal of NO and Hg⁰ were6.16g/?kWh?and 0.22?g/kJ,respectively.