In the troposphere, ozone is a harmful gas compound to both human health and vegetation. Ozone is produced from the reaction of NO_x(@NO + NO_2) and VOCs(volatile organic compounds) with light. Due to the highly nonli...In the troposphere, ozone is a harmful gas compound to both human health and vegetation. Ozone is produced from the reaction of NO_x(@NO + NO_2) and VOCs(volatile organic compounds) with light. Due to the highly nonlinear relationships between ozone and its precursors, proper ozone mitigation relies on the knowledge of chemical mechanisms. In this study, an observation-based method is used to simulate ozone formation and elucidate its controlling factors for a rural site on the North China Plain. The instantaneous ozone production rate is calculated utilizing a box model using the dataset obtained from the Wangdu campaign. First, the model was operated in a time-dependent mode to calculate the ozone production rate at each time stamp. The calculated ozone formation rate showed a diurnal average maximum value of 17 ppbv/h(1-h diurnal averaged). The contribution of individual peroxy radicals to ozone production was analyzed. In addition, the functional dependence of calculated P(O_3) reveals that ozone production was in a NO_x-limited regime during the campaign. Furthermore, the missing peroxy radical source will further extend NO_x-limited conditions to earlier in the day, making NO_xlimitation dominate more of a day than the current chemical model predicts. Finally, a multiple scenarios mode,also known as EKMA(empirical kinetic modeling approach), was used to simulate the response of P(O_3) to the imaginary change in precursor concentrations. We found that ozone production was in the NO_x-limited region. However, the use of NO_2 measured by the molybdenum converter and/or the absence of a peroxy radical source in the current chemical model could over-emphasize the VOC-limited effect on ozone production.展开更多
Abstract The detailed kinetic model of selective non-catalytic reduction （SNCR） of nitric oxide, including so-dium species reactions, was deyeloped on the basis of recent studies on thermal DeNOx mechanism, NOxOUTme...Abstract The detailed kinetic model of selective non-catalytic reduction （SNCR） of nitric oxide, including so-dium species reactions, was deyeloped on the basis of recent studies on thermal DeNOx mechanism, NOxOUTmechanism and promotion mechanism of Na2CO3. The model was validated by comparison with several experi-mental findings, thus providing an effective tool for the primary and promoted SNCR process simulation. Experimental and simulated results show part-per-million level of sodium carbonate enhances NO removal efficiency andextend the effective SNCR temperature range in comparison with use of a nitrogen agent alone. The kinetic modeling, sensitivity and rate-of-production analysis suggest that the performance improvement can be explained as ho-mogeneous sodium species reactions producing more reactive OH radicals. The net result of sodium species reac-tions is conversion of H2O and inactive HO2 radicals into reactive OH radicals, i.e. H2O＋HO2=3OH, which enhances the SNCR performance of nitrogen agents by mainly increasing the production rate of NH2 radicals. More-over, N2O and CO are eliminated diversely via the reactions Na＋N20=NaO＋N2, NaO＋CO=Na＋CO2 andNaO2＋CO =NaO＋CO2, in.the pro.moted SNCR process, especially in the NOxOUT process.展开更多
基金supported from the research projects of the Environmental Public Welfare Industry in China (201509001,201409005)the National Science and Technology Support Program of China (2014BAC21B01)+2 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB05010500)the Special Fund of State Key Joint Laboratory of Environment Simulation and Pollution Control (18K03ESPCP)the EU-project AMIS (Fate and Impact of Atmospheric Pollutants,PIRSES-GA-2011295132)
文摘In the troposphere, ozone is a harmful gas compound to both human health and vegetation. Ozone is produced from the reaction of NO_x(@NO + NO_2) and VOCs(volatile organic compounds) with light. Due to the highly nonlinear relationships between ozone and its precursors, proper ozone mitigation relies on the knowledge of chemical mechanisms. In this study, an observation-based method is used to simulate ozone formation and elucidate its controlling factors for a rural site on the North China Plain. The instantaneous ozone production rate is calculated utilizing a box model using the dataset obtained from the Wangdu campaign. First, the model was operated in a time-dependent mode to calculate the ozone production rate at each time stamp. The calculated ozone formation rate showed a diurnal average maximum value of 17 ppbv/h(1-h diurnal averaged). The contribution of individual peroxy radicals to ozone production was analyzed. In addition, the functional dependence of calculated P(O_3) reveals that ozone production was in a NO_x-limited regime during the campaign. Furthermore, the missing peroxy radical source will further extend NO_x-limited conditions to earlier in the day, making NO_xlimitation dominate more of a day than the current chemical model predicts. Finally, a multiple scenarios mode,also known as EKMA(empirical kinetic modeling approach), was used to simulate the response of P(O_3) to the imaginary change in precursor concentrations. We found that ozone production was in the NO_x-limited region. However, the use of NO_2 measured by the molybdenum converter and/or the absence of a peroxy radical source in the current chemical model could over-emphasize the VOC-limited effect on ozone production.
基金Supported by the Natural Science Foundation of Shandong Province （No.Z2006F04） and Science and Technology Program for Environment Protection of Shandong Province （No.2006046）.
文摘Abstract The detailed kinetic model of selective non-catalytic reduction （SNCR） of nitric oxide, including so-dium species reactions, was deyeloped on the basis of recent studies on thermal DeNOx mechanism, NOxOUTmechanism and promotion mechanism of Na2CO3. The model was validated by comparison with several experi-mental findings, thus providing an effective tool for the primary and promoted SNCR process simulation. Experimental and simulated results show part-per-million level of sodium carbonate enhances NO removal efficiency andextend the effective SNCR temperature range in comparison with use of a nitrogen agent alone. The kinetic modeling, sensitivity and rate-of-production analysis suggest that the performance improvement can be explained as ho-mogeneous sodium species reactions producing more reactive OH radicals. The net result of sodium species reac-tions is conversion of H2O and inactive HO2 radicals into reactive OH radicals, i.e. H2O＋HO2=3OH, which enhances the SNCR performance of nitrogen agents by mainly increasing the production rate of NH2 radicals. More-over, N2O and CO are eliminated diversely via the reactions Na＋N20=NaO＋N2, NaO＋CO=Na＋CO2 andNaO2＋CO =NaO＋CO2, in.the pro.moted SNCR process, especially in the NOxOUT process.
