Modeling nitrogen chemistry in combustion

Glarborg, Peter; Miller, James A.; Ruščić, Branko; Klippenstein, Stephen J.

doi:10.1016/j.pecs.2018.01.002

Cited by 1,305 publications

(821 citation statements)

References 387 publications

(417 reference statements)

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“…Computational fluid dynamics modeling of the catalytic partial oxidation process is complex [15,16], especially when the role of reaction pathway needs to be determined [66]. Therefore, detailed reaction mechanisms are included in the model.…”

Section: Reaction Mechanismsmentioning

confidence: 99%

RETRACTED: Computational Fluid Dynamics Modeling of the Catalytic Partial Oxidation of Methane in Microchannel Reactors for Synthesis Gas Production

Chen

Song

2018

Processes

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This paper addresses the issues related to the favorable operating conditions for the small-scale production of synthesis gas from the catalytic partial oxidation of methane over rhodium. Numerical simulations were performed by means of computational fluid dynamics to explore the key factors influencing the yield of synthesis gas. The effect of mixture composition, pressure, preheating temperature, and reactor dimension was evaluated to identify conditions that favor a high yield of synthesis gas. The relative importance of heterogeneous and homogenous reaction pathways in determining the distribution of reaction products was investigated. The results indicated that there is competition between the partial and total oxidation reactions occurring in the system, which is responsible for the distribution of reaction products. The contribution of heterogeneous and homogeneous reaction pathways depends upon process conditions. The temperature and pressure play an important role in determining the fuel conversion and the synthesis gas yield. Undesired homogeneous reactions are favored in large reactors, and at high temperatures and pressures, whereas desired heterogeneous reactions are favored in small reactors, and at low temperatures and pressures. At atmospheric pressure, the selectivity to synthesis gas is higher than 98% at preheating temperatures above 900 K when oxygen is used as the oxidant. At pressures below 1.0 MPa, alteration of the dimension in the range of 0.3 and 1.5 mm does not result in significant difference in reactor performance, if made at constant inlet flow velocities. Air shows great promise as the oxidant, especially at industrially relevant pressure 3.0 MPa, thereby effectively inhibiting the initiation of undesired homogeneous reactions.

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Section: Reaction Mechanismsmentioning

confidence: 99%

RETRACTED: Computational Fluid Dynamics Modeling of the Catalytic Partial Oxidation of Methane in Microchannel Reactors for Synthesis Gas Production

Chen

Song

2018

Processes

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“…The prompt pathway has been revised in fairly recent studies that identified the formation of the NCN species as the most important initial step of the prompt route (Cui et al, 1999;Moskaleva and Lin, 2000). The kinetic parameters of the reaction of NCN formation, CH + N 2 ⇋ NCN + H, have been established within a factor of two by several experimental and modeling investigations (Vasudevan et al, 2007;Harding et al, 2008;Sutton et al, 2012;Klippenstein et al, 2018) and included in novel mechanisms (Lamoureux et al, 2016;Glarborg et al, 2018;Song et al, 2019). Since the CH species is produced by the oxidation of hydrocarbons and forms the NCN species by insertion into the triple bond of molecular nitrogen, the predictions of NO x emissions via the prompt route is also affected by the accuracy of the kinetic mechanisms of hydrocarbon oxidation (Santner et al, 2016).…”

Section: Chemistry Of No X Formation In Mild Combustionmentioning

confidence: 99%

“…The kinetics of this route is still under investigation: the uncertainty in the heat of formation of NNH may alter the NO predictions by a factor of two (Klippenstein et al, 2011), and the rate constants for the limiting reaction NNH + O ⇋ NH + NO reported in the literature (Bozzelli and Dean, 1995;Hayhurst and Hutchinson, 1998;Konnov et al, 2001;Haworth et al, 2003;Klippenstein et al, 2011) vary by more than an order of magnitude. However, recent kinetic models (Zhang et al, 2017;Glarborg et al, 2018;Song et al, 2019) have been updated with thermo-chemical and kinetic quantities estimated via ab initio transition state calculations (Klippenstein et al, 2011). The inclusion of the N 2 O and NNH routes has been crucial in obtaining accurate predictions of NO emissions for several lab-scale burners (Galletti et al, 2009;Mardani and Tabejamaat, 2012;Wang et al, 2015) and semi-industrial furnaces (Parente et al, 2011;Li et al, 2013) operating in MILD conditions.…”

Section: Chemistry Of No X Formation In Mild Combustionmentioning

confidence: 99%

NOx Formation in MILD Combustion: Potential and Limitations of Existing Approaches in CFD

Iavarone

Parente

2020

Front. Mech. Eng.

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Emissions of nitrogen oxides (NO x ) from combustion systems remain a lingering environmental issue, being these species either greenhouse gases or acid rain precursors. Moderate or Intense Low-oxygen Dilution (MILD) combustion can reduce the emissions of NO x thanks to its characteristic features (i.e., homogeneous reaction zones, reduced temperature peaks, diluted mixtures of reactants) that influence and change the main chemical pathways of NO x formation. A summary of the relevant routes of formation and destruction of NO x in MILD combustion is presented in this review, along with the identification of the sources of uncertainty that prevent reaching an overall consensus in the literature about the dominant NO x chemical pathway in MILD regime. Computational Fluid Dynamics (CFD) approaches are essential tools for investigating the critical phenomena occurring in MILD combustion and the design of pollutant-free turbulent combustion systems. This paper provides an outline of the modeling approaches employed in CFD simulations of turbulent combustion systems to predict NO x emissions in MILD conditions. An assessment of the performances of selected models in estimating NO x formation in a lab-scale MILD combustion burner is then presented, followed by a discussion about relevant modeling issues, perspectives and opportunities for future research.

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“…Furthermore, the two global subsequent competing reactions comprise several single competing reactions (e.g., Eq. (5) [5]. Nevertheless, the above global representation provides a reasonable basis for an engineering approach, and the complexity of the underlying detailed mechanism would be contained in correlations describing the dependence of the kinetics-equilibrium mole fraction of nitric oxide on process conditions.…”

Section: Fenimore's Basic Model Of Fuel-nitrogen Conversionmentioning

confidence: 99%

An Engineering Approach for Estimating the Formation of Nitric Oxide from Fuel‐Nitrogen

Förtsch

2019

Chem Eng & Technol

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Explicit approximate equations for estimating the conversion factor of fuel‐nitrogen into nitric oxide are presented. They depend on the fuel‐nitrogen mole fraction, the initial nitric oxide mole fraction, and the kinetics‐equilibrium mole fraction of nitric oxide. This last parameter expresses a limiting value of fuel‐nitrogen conversion; it includes the complex nitrogen chemistry and depends thus on combustion conditions. Experimental results demonstrate that the kinetics‐equilibrium mole fraction for fuel‐lean and high‐temperature conditions can be well estimated by the chemical‐equilibrium mole fraction, but for lower temperatures the kinetics‐equilibrium mole fraction has to be described by other correlations.

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Modeling nitrogen chemistry in combustion

Cited by 1,305 publications

References 387 publications

RETRACTED: Computational Fluid Dynamics Modeling of the Catalytic Partial Oxidation of Methane in Microchannel Reactors for Synthesis Gas Production

RETRACTED: Computational Fluid Dynamics Modeling of the Catalytic Partial Oxidation of Methane in Microchannel Reactors for Synthesis Gas Production

NOx Formation in MILD Combustion: Potential and Limitations of Existing Approaches in CFD

An Engineering Approach for Estimating the Formation of Nitric Oxide from Fuel‐Nitrogen

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