Oxides of nitrogen formed in high-intensity methanol combustion

Singh, S. P.; Grosshandler, William L.; Malte, Philip C.; Crain, Richard W.

doi:10.1016/s0082-0784(79)80068-5

Cited by 19 publications

(14 citation statements)

References 9 publications

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“…The nitrous oxide pathway is given below by reactions (4) through (11). The mechanism is initiated by the reverse rates of reactions (4) and (4a), and the N20 formed is then oxidized to NO mainly by reaction (5), but also forms by reactions (8), (10), and (11). The N20 is reduced to N2 by reactions (4), (4a), (6), (7), and (9).…”

Section: Nitrous Oxidementioning

confidence: 99%

“…In Figure 2, results of Corr et al [7], Bartok et al [8], Malte et al [9], and Singh et al [10] are plotted. The fuel-rich data of [8] and [9] have not been included, and only single data points have been used from [7] and [10], since the remainder of their data were obtained in combustion gases diluted by an inert in order to maintain a constant temperature. Also, not all of the lean data of [8] residence times of [8] led to enhanced free radical concentrations, and therefore, to greater NOx yields.…”

Section: Nox Trendsmentioning

confidence: 99%

“…The pressure is latm for [7] and [8], and 0.92atm for [9] and [10]. The reactant inlet temperature is 464K for [8], and 295K (nominal) for the other data.…”

Section: Nox Pathwaysmentioning

confidence: 99%

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The Importance of the Nitrous Oxide Pathway to NOx in Lean-Premixed Combustion

et al. 1993

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This study addresses the importance of the different chemical pathways responsible for NOx formation in lean-premixed combustion, and especially the role of the nitrous oxide pathway relative to the traditional Zeldovich pathway. NOx formation is modeled and computed over a range of operating conditions for the lean-premixed primary zone of gas turbine engine combustors. The primary zone, of uniform fuel-air ratio, is modeled as a micro-mixed well-stirred reactor, representing the flame zone, followed by a series of plug flow reactors, representing the post-flame zone. The fuel is methane. The fuel-air equivalence ratio is varied from 0.5 to 0.7. The chemical reactor model permits study of the three pathways by which NOx forms, which are the Zeldovich, nitrous oxide, and prompt pathways. Modeling is also performed for the well-stirred reactor alone. Three recently published, complete chemical kinetic mechanisms for the C1-C2 hydrocarbon oxidation and the NOx formation are applied and compared. Verification of the model is based on the comparison of its NOx output to experimental results published for atmospheric pressure jet-stirred reactors and for a ten atmosphere porous-plate burner. Good agreement between the modeled results and the measurements is obtained for most of the jet-stirred reactor operating range. For the porous-plate burner, the model shows agreement to the NOx measurements within a factor of two, with close agreement occurring at the leanest and coolest cases examined. For lean-premixed combustion at gas turbine engine conditions, the nitrous oxide pathway is found to be important, though the Zeldovich pathway cannot be neglected. The prompt pathway, however, contributes small-to-negligible NOx. Whenever the NOx emission is in the 15 to 30ppmv (15% O2, dry) range, the nitrous oxide pathway is predicted to contribute 40 to 45% of the NOx for high pressure engines (30atm), and 20 to 35% of the NOx for intermediate pressure engines (10atm). For conditions producing NOx of less than 10ppmv (15% O2, dry), the nitrous oxide contribution increases steeply and approaches 100%. For lean-premixed combustion in the atmospheric pressure jet-stirred reactors, different behavior is found. All three pathways contribute; none can be dismissed. No universal behavior is found for the pressure dependence of the NOx. It does appear, however, that lean-premixed combustors operated in the vicinity of 10atm have a relatively weak pressure dependence, whereas combustors operated in the vicinity of 30atm have an approximately square root pressure dependence of the NOx.

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Section: Nitrous Oxidementioning

confidence: 99%

Section: Nox Trendsmentioning

confidence: 99%

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The Importance of the Nitrous Oxide Pathway to NOx in Lean-Premixed Combustion

et al. 1993

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“…This has spawned a considerable interest in its oxidation chemistry. Oxidation of methanol has been studied at high temperatures in shock tubes 1–4, jet‐stirred reactors 5, and flames 6–10, and in the low‐to‐medium temperature range in batch reactors 11, flow reactors 12–16, and supercritical water 17–21. The comprehensive studies of this chemistry 22–25 discuss much of the published work.…”

Section: Introductionmentioning

confidence: 99%

Methanol oxidation in a flow reactor: Implications for the branching ratio of the CH₃OH+OH reaction

Rasmussen

Wassard

Dam‐Johansen

et al. 2008

Int J of Chemical Kinetics

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The oxidation of methanol in a flow reactor has been studied experimentally under diluted, fuel-lean conditions at 650-1350 K, over a wide range of O 2 concentrations (1%-16%), and with and without the presence of nitric oxide. The reaction is initiated above 900 K, with the oxidation rate decreasing slightly with the increasing O 2 concentration. Addition of NO results in a mutually promoted oxidation of CH 3 OH and NO in the 750-1100 K range. The experimental results are interpreted in terms of a revised chemical kinetic model. Owing to the high sensitivity of the mutual sensitization of CH 3 OH and NO oxidation to the partitioning of CH 3 O and CH 2 OH, the CH 3 OH + OH branching fraction could be estimated as α = 0.10 ± 0.05 at 990 K. Combined with low-temperature measurements, this value implies a branching fraction that is largely independent of temperature. It is in good agreement with recent theoretical estimates, but considerably lower than values employed in previous modeling studies. Modeling predictions with the present chemical kinetic model is in quantitative agreement with experimental results below 1100 K, but at higher temperatures and high O 2 concentration the model underpredicts the oxidation rate.

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“…Evidence for the suppression of prompt NO in methanol combustion is also provided by the research of Singh et al (1978). Significant decreases in NO x from methane to methanol combustion were observed for the 0.75 to 1.35 fuel-air equivalence ratio range nm in a 50 cc JSR operated at 1870 K and 1 atm.…”

Section: Additional Evidence and Considerationsmentioning

confidence: 77%

NOX as a Function of Fuel Type: C1-to-C16 Hydrocarbons and Methanol

Lee

Malte

Nicol

1999

Volume 2: Coal, Biomass and Alternative Fuels; Combustion and Fuels; Oil and Gas Applications; Cycle Innovations

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The response of NOx to fuel type is determined for leanprevaporized-premixed combustion in an atmospheric pressure jetstirred reactor (JSR). Pure, straight chain, alkane fuels from C1 (methane) to C16 (hexadecane) and methanol are tested Testing is conducted under three conditions, each of which is obtained using a particular inlet-jet nozzle for the JSR. For a selected condition, the fuels are bunted under nearly identical macroscopic thermal and fluid mechanical fields in the JSR. A constant mixture inlet total temperature is used that provides for complete vaporization of all of the fuels tested without causing pre-flame reactions in the prembud. Two of the nozzles used have single, centered jets and provide a nominal combustion temperature of 1790 K The third nozzle has eight diverging jets. In this case, the fuel-air equivalence ratio is increased, providing a nominal combustion temperature of 1850 K Lowest levels of NOx are measured when methanol is burned Upon switching to methane, the NOx concentration increases by 62±10%. For the &lame fuels, methane combustion yields the lead amount of NOx. Upon switching from methane to ethane, the NO increases by 22±2%. Further increases in the size of the alkane fuel molecule (from C2 ICI C16) show small increases (81:5%) in the NO concentration. Although the JSR-condition selected affects the absolute NOx concentration, the trends in NO x concentration with respect to fuel-type are the same for the three conditions usedThe JSR is modeled as a single perfectly stirred reactor (PSR) operating at the experimental residence time and combustion temperature. This modeling shows that the increase in the NO, measured for the alkane fuels may be explained in terms of the increase in 0-atom concentration with increasing C/H ratio. In order to explore the effect of Fenimore prompt NO x, a two-PSRs-in-series model is used The first PSR is assigned a residence time equal to 5% the total residence time of the reactor. The second PSR accounts for the remaining 95% of the reactor residence time. Because of its short lifetime, the CH radical is effectively restricted to the first PSR, and prompt NOx mainly forms in this zone. Mechanisms directly dependent on the 0-atom form NO x throughout the reactor. The modeling suggests that prompt NOx is responsible for the greater concentration of NOx found in the methane combustion compared to the methanol combustion.

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Oxides of nitrogen formed in high-intensity methanol combustion

Cited by 19 publications

References 9 publications

The Importance of the Nitrous Oxide Pathway to NOx in Lean-Premixed Combustion

The Importance of the Nitrous Oxide Pathway to NOx in Lean-Premixed Combustion

Methanol oxidation in a flow reactor: Implications for the branching ratio of the CH₃OH+OH reaction

NOX as a Function of Fuel Type: C1-to-C16 Hydrocarbons and Methanol

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Oxides of nitrogen formed in high-intensity methanol combustion

Cited by 19 publications

References 9 publications

The Importance of the Nitrous Oxide Pathway to NOx in Lean-Premixed Combustion

The Importance of the Nitrous Oxide Pathway to NOx in Lean-Premixed Combustion

Methanol oxidation in a flow reactor: Implications for the branching ratio of the CH3OH+OH reaction

NOX as a Function of Fuel Type: C1-to-C16 Hydrocarbons and Methanol

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Methanol oxidation in a flow reactor: Implications for the branching ratio of the CH₃OH+OH reaction