Research On Exhaust Gas Treatment By Synergistic Catalysis Of Glow Plasma

With the continuous development of our country’s society and economy,pollution problems caused by exhaust emissions are becoming more and more serious.Plasma is a promising exhaust gas treatment technology which can remove SO₂,NO_X,and VOCs in the exhaust gas,and can improve the efficiency of pollutant treatment under the cooperation of catalysts.This thesis mainly focuses on the exhaust gas treatment of glow plasma synergistic catalysis.An electrode structure which can withstand high temperature and carry catalyst in the environment of industrial exhaust gas is designed.Simulation and experimental analysis were carried out.The flow of gas in the electrode module is simulated and analyzed,and the discharge characteristics under air and exhaust gas are compared.Six kinds of reactors were made with different electrode structures and catalysts,and the treatment platform was built.The experimental study of exhaust gas treatment was carried out.First,a high-frequency and high-voltage power supply for glow plasma was fabricated,with a voltage output amplitude of 0～±7 k V and a frequency of 5～25 k Hz.Based on the dielectric barrier discharge model and combined with exhaust gas treatment applications,glass fiber dielectric barrier spiral contact electrodes,multi-anode spiral contact electrodes,and multi-potential spiral contact electrodes are proposed,and their discharge characteristics are simulated and tested by changing electrode parameters analysis.Research on the glass fiber dielectric barrier spiral contact electrode found that glass fiber is a good inorganic electret material,which can withstand high temperatures and adhere to catalysts.The electrode forms an uneven electric field in the space,and the surface shows a uniform and stable light blue discharge phenomenon during discharge,and the discharge current is in the milliampere level.Research on the multi-anode helical contact electrode found that the electric field intensity at the contact point increases gradually with the increase of the number of anodes,and the discharge is more likely to occur.Research on multi-potential spiral contact electrodes found that two spiral contact electrodes with opposite voltages can increase the electric field strength of adjacent surfaces.Under a gap of 1.8 mm,the electric field strength in the middle area of the two electrodes reaches above 10⁶.During discharge,the entire electrode surface and the middle area show a diffuse light blue discharge phenomenon,and the discharge current is at the milliampere level.Secondly,an array electrode module was fabricated according to the proposed single electrode structure.Through the staggered arrangement of multiple electrodes,the electric power lines are staggered and crisscrossed with each other,which can realize large-area glow discharge applied in industry,and the discharge phenomenon is good.In the electrode module fluid simulation,the arrangement of the electrodes in the reactor makes the gas flow turbulent in the reactor,thereby achieving a good contact effect between the gas molecules and the plasma generation area.A comparison is made between the discharge in the exhaust gas and the air environment.Due to the changes in O₂ content and flow rate,the discharge power of the electrode in the air is greater than the discharge power in the exhaust gas.Spectral analysis shows that the high-energy electrons generated by the discharge can break the molecular bonds of the reactants and realize the pollutant disposal.Finally,an experimental study on plasma co-catalyzed exhaust gas treatment was carried out.In the separate desulfurization and denitrification processes,the influence of electrode parameters,exhaust gas temperature,and reactant parameters on desulfurization and denitrification was studied,and the highest desulfurization rate of99.4%and a denitrification rate of 78.5%were achieved.In the simultaneous desulfurization and denitrification experiments,the highest 99.1%desulfurization rate and 77%denitrification rate were reached,and the denitrification rate was 33%higher than that of the previous laboratory treatment with plasma at low temperature.Preliminary experiments on the purification of VOCs were carried out,and the highest96%formaldehyde removal rate and 94.1%TVOC removal rate were obtained under plasma synergistic catalysis.