Experimental Study On Non-Thermal Plasma-Assisted Denitrification

As one of the main pollutants in the atmosphere,nitrogen oxides are highly concerned for their formation of acid rain and the initiation of photochemical smog.In China,coal-fired boilers are an important source of nitrogen oxides.The traditional selective catalytic reduction(SCR)denitration can not meet the requirements of the regulations during peak load operation under low load,which will reduce the removal rate of nitrogen oxide and lead the leakage of ammonia.The use of non-thermal plasma technology can increase the removal rate of nitrogen oxide without increasing the temperature of the inlet gas in the SCR section,which has a great advantage.In this thesis,wire-plate corona discharge,dielectric barrier discharge(DBD)and its co-catalytic denitrification,DBD ammonia activation and its co-catalytic denitrification are studied.They provide references for industrial applications.The main conclusions are as follows:(1)For corona denitrification,in general,the removal rate of nitrogen oxides increases with the increase of specific inputenergy(SIE);increasing the number of high-voltage electrodes is an effective way to increase SIE.However,the relationship between energy yield(EY)and the volume of the ionization zone is found in the experiment.When the ionization zone almost fills the space,increasing the number of high-voltage electrodes does not improve EY;the removal rate and EY of nitrogen oxides under positive high voltage are better than negative voltage.(2)For DBD denitrification,in general,the nitrogen oxide removal rate increases with the increase of SIE,and the EY decreases with the increase of SIE;removal rate of nitrogen oxide and EY decrease with the increase of oxygen concentration,ammonia concentration and temperature.In DBD co-catalytic denitrification,in general,the nitrogen oxide removal rate increases with the increase of SIE,and the EY increases first and then decreases with the increase of SIE;the EY reaches the maximum at 150-200 ℃.It decreases with the increase of ammonia concentration and does not change with oxygen concentration.(3)For DBD ammonia activation denitrification,in the absence of catalyst,the removal rate of nitrogen oxide increases with the increase of temperature and SIE at room temperature to 250℃.With catalysts,the same conclusion can be drawn at room temperature to 200℃.However,the removal rate of nitrogen oxides in the absence of catalyst is significantly less than that with catalysts,and will produce a large amount of NO2.(4)For corona denitrification,the EY of the line saw blade under positive high voltage is the highest,and when SIE is 150 J/L,EY can reach 1.8 g/kWh.For DBD denitration at 150℃,the EY of the same SIE is 1.1 g/kWh,and EY of DBD co-catalysis is 2.2 g/kWh.Under same conditions,the EY of DBD ammonia activation denitration is 0.06 g/kWh,and the EY of its co-catalysis is 0.19 g/kWh.