Experimental And Mechanism Study On The Removal Of Nitrogen Oxides In Flue Gas With Ozone Deely Oxidation Treatment

Currently,traditional fossil fuels are still the dominant sources of China's energy consumption,leading to serious pollution problems with SO_x,NO_x,Hg,VOCs and PM which are harmful to our health and the environment.Nowadays,simultaneous removal of multi-pollutants and ultra-low emission become an irreversible trend instead of the technology aiming at single pollutant.In this paper,industrial boiler that using alkaline solution as the spray liquid is treated as an example to discuss the removal efficiency of nitrogen oxide by ozone oxidation treatment.The mechanism of ozone oxidation and removal of nitrogen oxide in flue gas was studied and the main contents are summarized as below:1st,by ozone oxidizing NOx in flue gas by ozone at 150 degree centigrade,the relationship between O₃/NO molar ratio was carried out.At this temperature,NO was converted into NO₂ when O₃/NO molar ratio was lower than 1.2,and the existing of SO₂ had unremarkable effect on the oxidation efficiency of NO.2nd,the oxidation product of flue gas was removed by Na₂S₂O₃ solution in the spray tower.The effect of concentration of Na₂S₂O₃,concentration of SO₂,pH on the NOx removal efficiency was discussed.Results of the experiment showed that at the O₃/NO molar ratio of 1.1?1.2,with 2%Na₂S₂O₃ solution spraying,SO₂ would be removed with high efficiency and the NOx removal efficiency reached 60%.Na₂S₂O₃ would hardly be oxided by oxygen,and the NO_x was dominantly converted into NO₂^-.3rd,fully deep oxidation by ozone and absorption by the Na₂CO₃ solution in the spray tower was carried out.At the temperature of 70?,molar ratio of O₃/NO above 2.41,all of the NO in the flue gas was converted into N₂O₅.There was a positive correlation between NO_x removal efficiency of the system and the liquid-gas ratio,the concentration of Na₂CO₃ and residence time of gas in spray tower.4th,deep unfullly oxidation by ozone and spraying with Na₂CO₃ solution was carried out.The concentration of NO₂ at the outlet of reaction chamber increased when the time of oxidation decreased at the deep unfullly oxidation situation.There was a positive correlation between NO_x removal efficiency of the system and the liquid-gas ratio,the concentration of Na₂CO₃ and residence time of gas in spray tower,while there was a negative correlation between NO_x removal efficiency and the concentration of SO₂ in flue gas.The NO_x was dominantly converted into NO₃-in spray solution.And the technology of deep unfullly oxidation by ozone combine with spraying had been applied in industrial application.5th,the sorption of NO₃-of 717 anion exchanging resin with pre-treated finished in 10 min.SO₄^2- showed higher effet on the sorption efficiency than CO₃^2- and HCO₃^-.In the pH range of industrial spray solution,pH showed little effect on the sorption efficiency of NO₃^-.