CFD-based simulation to reduce greenhouse gas emissions from industrial plants

Greenhouse gas (GHG) pollution is considered one of the challenging concerns in industrial plants, and to emit the appropriate designation in nitrogen oxide reduction, it is required to implement proper numerical simulation procedures. In this study, ANSYS Fluent® software is used as dynamic software to solve heat and mass flow transfer numerically by considering non-structured networks for complex geometries. Dry nitrogen oxide burners have an additional thermocouple to provide an extra fuel pathway to combine with air. Then, standard K-ε is used in the numerical simulations to calculate thermal efficiency in combustion processes for turbulent flow regimes. It can cause the removal of 50% of nitrogen oxide into the atmosphere. Furthermore, by the increase of temperature, nitrogen oxide concentration has been increased in the system. After 1975 K, Fuel has been changed to dry fuel, and therefore nitrogen oxide concentration increased because the steam can provide a relatively non-combustible compound increase than fuel. On the other hand, regarding the water volume increase at inlet steam, nitrogen oxide volume percentage has been decreased dramatically, especially in the first periods of water volume increase. Consequently, when the steam percentage is increased instead of water, nitrogen oxide reduction is increased. Moreover, our simulation results have a proper match with Gibbs energy equilibrium.

EVALUATION OF CONTENT OF NITROGEN OXIDES IN COMBUSTION PRODUCTS OF GASEOUS FUELS

Formation mechanisms of nitrogen oxides in combustion products of gaseous fuels with different calorific efficiency under different firing conditions have been studied. It was found out that most important factors that influence on the nitrogen oxide concentration in outgoing gases were a fuel firing temperature, a furnace temperature and heating the firing air that sharply (more than 1.5 time) increased content of nitrogen oxides in the combustion products.

Evaluation of OH and HO₂ concentrations and their budgets during photooxidation of 2-methyl-3-butene-2-ol (MBO) in the atmospheric simulation chamber SAPHIR

Several previous field studies have reported unexpectedly large concentrations of hydroxyl and hydroperoxyl radicals (OH and HO2, respectively) in forested environments that could not be explained by the traditional oxidation mechanisms that largely underestimated the observations. These environments were characterized by large concentrations of biogenic volatile organic compounds (BVOC) and low nitrogen oxide concentration. In isoprene-dominated environments, models developed to simulate atmospheric photochemistry generally underestimated the observed OH radical concentrations. In contrast, HO2 radical concentration showed large discrepancies with model simulations mainly in non-isoprene-dominated forested environments. An abundant BVOC emitted by lodgepole and ponderosa pines is 2-methyl-3-butene-2-ol (MBO), observed in large concentrations for studies where the HO2 concentration was poorly described by model simulations. In this work, the photooxidation of MBO by OH was investigated for NO concentrations lower than 200 pptv in the atmospheric simulation chamber SAPHIR at Forschungszentrum Jülich. Measurements of OH and HO2 radicals, OH reactivity (kOH), MBO, OH precursors, and organic products (acetone and formaldehyde) were used to test our current understanding of the OH-oxidation mechanisms for MBO by comparing measurements with model calculations. All the measured trace gases agreed well with the model results (within 15 %) indicating a well understood mechanism for the MBO oxidation by OH. Therefore, the oxidation of MBO cannot contribute to reconciling the unexplained high OH and HO2 radical concentrations found in previous field studies.

Evaluation of OH and HO₂ concentrations and their budgets during photo-oxidation of 2-methyl-3-butene-2-ol (MBO) in the atmospheric simulation chamber SAPHIR

Several field studies reported unexpected large concentrations of hydroxyl and hydroperoxyl radicals (OH and HO2, respectively) in forested environments that could not be explained by the traditional oxidation mechanisms which largely underestimated the observations. These environments were characterized by large concentrations of biogenic volatile organic compounds (BVOC) and low nitrogen oxide concentration. In isoprene-dominated environments, models developed to simulate atmospheric photochemistry generally underestimated the observed OH radical concentrations. In contrast, HO2 radical concentration showed large discrepancies with model simulations mainly in non-isoprene dominated forested environments. An abundant BVOC emitted by lodgepole and ponderosa pines is 2-methyl-3-butene-2-ol (MBO), observed in large concentrations for studies where the HO2 concentration was poorly described by model simulations. In this work, the photooxidation of MBO by OH was investigated for NO concentrations lower than 200 pptv in the atmospheric simulation chamber SAPHIR at Forschungszentrum Jülich. Measurements of OH and HO2 radicals, OH reactivity (kOH), MBO, OH precursors and organic products (acetone and formaldehyde) were used to test our current understanding of the OH-oxidation mechanisms for MBO by comparing measurements with model calculations. All the measured trace gases agree well with the model results (within 15 %) indicating a well understood mechanism for the MBO oxidation by OH. Therefore, the oxidation of MBO cannot contribute to reconcile the unexplained high OH and HO2 radical concentrations found in previous field studies.