Mechanism Investigation On The Oxidation And Degradation Of Multiple Pollutants In Flue Gas By Ozone

Ozone oxidation combined with chemical scrubbing is one of the most promising technologies for the simultaneous removal of multiple pollutants in flue gas. This technology not only has the remarkable efficiency of the simultaneous removal of multiple pollutants, but also doesn't need large expenses for application. The investigation of this technology is significantly important for its wide application foreground. However, most of the efforts were focused on the macroscopical experimental investigations and little attention has been paid to the microcosmic mechanism and kinetics. To further improve this technology, detailed investigation on the mechanisms and kinetics of the oxidation and degradation of multiple pollutants in flue gas by ozone is essential. The mechanisms and kinetics of the oxidation of NO and Hg and the degradation of VOCs and dioxins by ozone in flue gas were systemically investigated using quantum chemistry,kinetic modeling and experimental research in this paper.The mechanism and kinetic of the NO oxidation by ozone in flue gas were investigated in detail using quantum chemistry,kinetic modeling and experimental research. Based on the established detailed kinetic model, the key elemental reactions were ascertained by sensitivity analyzing, and its reaction processes and kinetic parameters were calculated and analyzed using quantum chemistry. The calculated results were in good agreement with experimental results, and both the results were employed for kinetic modeling. Both the results of these two kinds kinetic modelling were in good agreement with our experimental results.The mechanism and kinetic of the elemental Hg oxidation by ozone in flue gas were investigated in detail using quantum chemistry,kinetic modeling and experimental research. The reaction processes,activation energy and kinetic parameters were calculated and analyzed using quantum chemistry. The calculated results were in good agreement with experimental results, and the kinetic parameters were employed for kinetic modeling. Results of sensitivity analysis indicated that, for affecting Hg0 oxidization, the reaction Hg+NO3=NO2+HgO was the key elemental reaction and the concentration of NO3 was the most important factor. Results of experimental research indicated that, Hg0 oxidization increases linearly when the mole ratio of O3/NO becomes larger or the reaction temperature become higher. The result of kinetic simulation was in good agreement with that of experimental research.Selecting ethylene and benzene as the typical VOCs, the mechanism and kinetic of VOCs degradation by ozone in flue gas were investigated in detail using quantum chemistry and kinetic modeling. The reaction processes,activation energy and kinetic parameters of the involved reactions were calculated and analyzed using quantum chemistry. The calculated results were in good agreement with experimental results. By comparing, it can be found that the rate constants of the degradation of ethylene and benzene by NO3 are much larger than that by O3, which indicated that the NO3 radical have much stronger ability to degrade ethylene than the O3 radical. For the degradation of benzene by ozone in flue gas, the sensitivity analysis and kinetic simulation were performed based on the established detailed kinetic model. Results indicated that, the formation of NO3 is the most important factor to affect the reduction of benzene, and the reaction of ozone and benzene is not the key elemental reaction; the benzene reduction improves with rising of the temperature, increasing of the amount of the added ozone and descending of initial concentration of benzene, but the variety of O2 concentration will not affect the reduction.Selecting 2,3,7,8-TCDD as the typical dioxins, the mechanism and kinetic of dioxins degradation by ozone in flue gas were calculated and discussed using quantum chemistry. The structure analysis indicated that, there are two ways to degrade 2,3,7,8-TCDD. One is cleaving the carbon-carbon double bond via addition reaction. The other is substituting the Cl atom via displacement reaction. The reaction processes and activation energy of the involved reactions were calculated and analyzed using quantum chemistry.2,3,7,8-TCDD was degraded to be a heterocycle and a series of chloracyl carbonyl Compounds by O3 via addition reaction, while the Cl atoms of 2,3,7,8-TCDD was substituted by NO3 via displacement reaction. By comparing, it can be found that the activation energy of the 2,3,7,8-TCDD degradation by O3 are much lower than that by NO3, which indicated that the O3 radical have much stronger ability to degrade 2,3,7,8-TCDD than the NO3 radical.