Effect of different concentration levels of CO2 and H2O on the oxidation of CO: Experiments and modeling

Abián, María; Giménez-López, Jorge; Bilbao, Rafael; Alzueta, María U.

doi:10.1016/j.proci.2010.05.078

Cited by 82 publications

(50 citation statements)

References 28 publications

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“…Our tests showed that all four mechanisms are able to reproduce the inhibiting effect of large CO 2 concentrations on CO oxidation observed by Abián et al [27] both for lean and rich conditions (see Fig. 4; only the case with the highest CO 2 content is shown here for better readability).…”

Section: Mechanism For Oxy-fuel Combustion Of Chsupporting

confidence: 58%

“…Recently, the influence of CO 2 and H 2 O on CO oxidation has been investigated by several researchers (e.g., [12,27]). Our tests showed that all four mechanisms are able to reproduce the inhibiting effect of large CO 2 concentrations on CO oxidation observed by Abián et al [27] both for lean and rich conditions (see Fig.…”

Section: Mechanism For Oxy-fuel Combustion Of Chmentioning

confidence: 99%

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Chemical kinetics mechanism for oxy-fuel combustion of mixtures of hydrogen sulfide and methane

Bongartz

Ghoniem

2015

Combustion and Flame

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Oxy-fuel combustion of sour gas, a mixture of natural gas (essentially methane (CH 4 )), carbon dioxide (CO 2 ), and hydrogen sulfide (H 2 S), could enable the utilization of large natural gas resources, especially when combined with enhanced oil recovery. In this work, a detailed chemical reaction mechanism for oxy-fuel combustion of sour gas is presented. To construct the mechanism, a CH 4 sub-mechanism was chosen based on a comparative validation study for oxy-fuel combustion. This mechanism was combined with a mechanism for H 2 S oxidation, and the sulfur sub-mechanism was then optimized to give better agreement with relevant experiments. The optimization targets included predictions for the laminar burning velocity, ignition delay time, and pyrolysis of H 2 S, and H 2 S oxidation in a flow reactor. The rate parameters of 15 sulfur reactions were varied in the optimization within their respective uncertainties. The optimized combined mechanism was validated against a larger set of experimental data over a wide range of conditions for oxidation of H 2 S and interactions between carbon and sulfur species. Improved overall agreement was achieved through the optimization and all important trends were captured in the modeling results. The optimized mechanism can be used to make qualitative and some quantitative predictions on the combustion behavior of sour gas. The remaining discrepancies highlight the current uncertainties in sulfur chemistry and underline the need for more accurate direct determination of several important rate constants as well as more validation data.

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Section: Mechanism For Oxy-fuel Combustion Of Chsupporting

confidence: 58%

Section: Mechanism For Oxy-fuel Combustion Of Chmentioning

confidence: 99%

Chemical kinetics mechanism for oxy-fuel combustion of mixtures of hydrogen sulfide and methane

Bongartz

Ghoniem

2015

Combustion and Flame

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“…Therefore, CH 4 is often the focus of O 2 /CO 2 combustion studies. Many studies have reported that CO 2 is not inert but participates in chemical reactions in its gas phase primarily through the reaction CO 2 + H = CO + OH (R1) (5)(6)(7)(8)(9)(10)(11)(12)(13) .…”

Section: Journal Of Thermal Science and Technologymentioning

confidence: 99%

“…The effect of R1 on the combustion process has been extensively studied (5)(6)(7)(8)(9)(10)(11)(12)(13) , and some studies have shown that CO 2 inhibits the oxidation of CH 4 because of the competition between reactions R1 and H + O 2 = O + OH (R3), the main chain branching reaction in the combustion process in a dilute flow reactor (7,10) . In contrast, our previous paper shows the role of CO 2 was to advance CH 4 oxidation during fuel-rich O 2 /CO 2 combustion where the concentrations of reactants were high because R3 became insignificant under fuel-rich condition, and R1 produced an abundance of OH radicals that were more active than the H radicals in hydrocarbon reactions in the specific temperature range (12,13) .…”

Section: Journal Of Thermal Science and Technologymentioning

confidence: 99%

“…R1 is not the only reaction in which CO 2 plays a role. Hydrocarbon radicals are able to react with CO 2 (5) , and some reactions are enhanced by CO 2 because of higher third body efficiencies for CO 2 than for those for N 2 (6,10) . However, the above chemical role of CO 2 in CH 4 oxidation has not been systematically investigated in fuel-rich O 2 /CO 2 combustion under various air ratios.…”

Section: Journal Of Thermal Science and Technologymentioning

confidence: 99%

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Experimental and Kinetic Studies of Chemical Role of CO2 in Hydrocarbon Oxidation during Fuel-Rich O2/CO2 Combustion

Watanabe

Kiatpanachart

Okazaki

2013

JTST

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Experimental and kinetic studies of the chemical role of CO 2 in hydrocarbon reactions were conducted in a fuel-rich CH 4 flat flame with air ratios varying from 0.60 to 0.74. Unburned hydrocarbons (CH 4 , C 2 H 2 , C 2 H 4 , and C 2 H 6 ) in O 2 /CO 2 combustion were found to be lower than those in air combustion. The differences in the CH 4 oxidation characteristics between the air and O 2 /CO 2 combustion were caused by the chemical role of CO 2 in the reaction R1 (CO 2 + H → CO + OH), R2 (CH 2 (S) + CO 2 → CH 2 O + CO), and higher third body efficiencies of CO 2 at an air ratio (= 0.62 where the concentrations of reactants were high. The role of CO 2 in R1, R2, and the higher third body efficiencies of CO 2 decreased the rate of CH 4 oxidation during the early stage of combustion, where O 2 was present. Even though R2 did not directly compete with the main chain branching reaction R3 (H + O 2 → H + OH) for H radicals, like R1 did, R2 changed the hydrocarbon reaction pathway, thereby decreasing the rate of R4 (CH 3 + HO 2 → CH 3 O + OH) which had negative sensitivity in CH 4 oxidation. However, we found that R1 and R2 advance CH 4 oxidation in the last stage of combustion where O 2 was mostly consumed. This is attributed to the fact that the reactions R1 and R2 were able to advance without the presence of O 2 , and that R1 produced OH radicals that were active in hydrocarbon oxidation in the specific temperature range and R2 enhanced hydrocarbon oxidation when the rate of R4 was insignificant. Although R1 was the dominant reaction to reduce unburned hydrocarbons in the O 2 /CO 2 combustion, the role of R2 was significant at  = 0.62. Meanwhile, when the air ratio was 0.74 where concentrations of reactants were relatively low, the chemical role of CO 2 is to only decrease the rate of CH 4 oxidation due to the presence of an excessive amount of O 2 .

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Formation of NO from N₂/O₂ Mixtures in a Flow Reactor: Toward an Accurate Prediction of Thermal NO

Abián

Alzueta

Glarborg

2015

Int J of Chemical Kinetics

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We have conducted flow reactor experiments for NO formation from N2/O2 mixtures at high temperatures and atmospheric pressure, controlling accurately temperature and reaction time. Under these conditions, atomic oxygen equilibrates rapidly with O2. The experimental results were interpreted by a detailed chemical model to determine the rate constant for the reaction N2 + O ⇌ NO + N (R1). We obtain k1 = 1.4 × 1014 exp(−38,300/T) cm3 mol−1 s−1 at 1700–1800 K, with an error limit of ±30%. This value is 25% below the recommendation of Baulch et al. for k1, while it corresponds to a value k1b of the reverse reaction 25% above the Baulch et al. evaluation. Combination of our results with literature values leads to a recommended rate constant for k1b of 9.4 × 1012 T0.14 cm3 mol−1 s−1 over 250–3000 K. This value, which reconciles the differences between the forward and reverse rate constant, is recommended for use in kinetic modeling.

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Effect of different concentration levels of CO2 and H2O on the oxidation of CO: Experiments and modeling

Cited by 82 publications

References 28 publications

Chemical kinetics mechanism for oxy-fuel combustion of mixtures of hydrogen sulfide and methane

Chemical kinetics mechanism for oxy-fuel combustion of mixtures of hydrogen sulfide and methane

Experimental and Kinetic Studies of Chemical Role of CO<sub>2</sub> in Hydrocarbon Oxidation during Fuel-Rich O<sub>2</sub>/CO<sub>2</sub> Combustion

Formation of NO from N₂/O₂ Mixtures in a Flow Reactor: Toward an Accurate Prediction of Thermal NO

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Effect of different concentration levels of CO2 and H2O on the oxidation of CO: Experiments and modeling

Cited by 82 publications

References 28 publications

Chemical kinetics mechanism for oxy-fuel combustion of mixtures of hydrogen sulfide and methane

Chemical kinetics mechanism for oxy-fuel combustion of mixtures of hydrogen sulfide and methane

Experimental and Kinetic Studies of Chemical Role of CO<sub>2</sub> in Hydrocarbon Oxidation during Fuel-Rich O<sub>2</sub>/CO<sub>2</sub> Combustion

Formation of NO from N2/O2 Mixtures in a Flow Reactor: Toward an Accurate Prediction of Thermal NO

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Formation of NO from N₂/O₂ Mixtures in a Flow Reactor: Toward an Accurate Prediction of Thermal NO