Products in methane combustion near surfaces

Vlachos, Dionisios G.; Schmidt, L.D.; Aris, Rutherford

doi:10.1002/aic.690400612

Cited by 18 publications

(17 citation statements)

References 15 publications

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“…The procedure, as applied for the reduced mechanism construction, removes the C 2 path from the combustion chemistry. It is well recognized that the C 2 path, which is a sequence of less well-understood steps, becomes important for sufficiently fuel-rich mixtures (e.g., Vlachos, 1994 andKee et al, 1989). The mechanism reduction with δ = 0.02 has already been used in combustion literature for mechanism reduction (e.g., Chang and Chen, 1997) that generated a set of 22 species, 104 reactions.…”

Section: Numerical Performance Of Reduced Mechanismmentioning

confidence: 99%

“…It is believed that wall quenching results in a reduction of free radicals near the wall and surface (Vlachos, 1994;Levis and von Elbe, 1987). OH, O, H and CH 3 consumption retards homogeneous ignition (Vlachos et al, 1994).…”

mentioning

confidence: 98%

“…The thermal coupling is thought to play an important role in combustion (Vlachos, 1994). The kinetic coupling between surface and gas phase becomes dominant in operations of fixed or fluidized bed reactors at moderately high temperatures.…”

mentioning

confidence: 99%

“…Therefore, a better understanding of how these particles influence the combustion mechanism of gaseous fuel becomes very important in fluidized bed reactors.Combustion phenomena are affected by inert particles surface through thermal and kinetic coupling with the homogeneous combustion. The thermal coupling is thought to play an important role in combustion (Vlachos, 1994). The kinetic coupling between surface and gas phase becomes dominant in operations of fixed or fluidized bed reactors at moderately high temperatures.…”

mentioning

confidence: 99%

“…Such effects may lower conversion as shown in the figure. Vlachos et al (1994) reported that the operating conditions and spatial heterogeneity (presence of solid surface) could largely affect product distributions. For example, removal of H atoms and CH 3 radicals by adsorption (Vlachos et al, 1994) can increase the ignition temperature.…”

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confidence: 99%

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The Heterogeneous and Homogeneous Combustion of Methane Over Inert Particles

Sotudeh‐Gharebagh

Chaouki

2003

Can J Chem Eng

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This effect was thought to explain the increase of homogeneous combustion ignition temperature in the presence of inert solid particles. The extent of inhibition varies with temperature and particle size distribution within the reactor (Chantravekin and Hesketh, 1993;Tringham, 1982). Moreover, it might be expected that inhibition by a solid surface would strongly affect the conversion of CO to CO 2 . It is worth mentioning that the role of particle surface on T he large amounts of energy needed for power generation and other applications depend on combustion of natural gas (mainly methane) in combustion devices, which may lead to some serious environmental problems. To solve these problems, the performance of the combustion devices should be improved in terms of efficiency and low emission levels through an understanding of elementary steps involved in combustion. As environmental regulations become more stringent, a better understanding of the mechanism and conditions, which lead to formation of undesired products, (i.e. CO, NO x and SO x ) becomes critical for optimization of combustors. Among the combustion devices, fluidized beds have so far been developed for promoting efficient combustion of fuel air mixtures with less pollution. Further improvement of combustion efficiency in fluidized bed reactors and reduction in pollutant emissions can be achieved using catalysts as bed materials. However, for power generation, this increases the operating costs and the currently accepted practice is to use inert particles as the bed materials. These materials are cheap, readily available and applicable to high temperature conditions. Such inert particles, when used in combustion devices, can considerably alter the combustion process because of heterogeneous inhibition reactions. Therefore, a better understanding of how these particles influence the combustion mechanism of gaseous fuel becomes very important in fluidized bed reactors.Combustion phenomena are affected by inert particles surface through thermal and kinetic coupling with the homogeneous combustion. The thermal coupling is thought to play an important role in combustion (Vlachos, 1994). The kinetic coupling between surface and gas phase becomes dominant in operations of fixed or fluidized bed reactors at moderately high temperatures. The coupling can be regarded as a catalytic or inhibition effect through intermediate species interaction which is common in both heterogeneous and homogeneous phases. The extent of the contribution from catalytic reaction on solid inert particles is still unknown. For alumina particles for example, Broughton (1972) reported that it has no significant accelerating catalytic effect. However, further work is still needed in order to conclude correctly on catalytic effects of different inert particles on the combustion mechanism.Besides their catalytic activities, solid particles may inhibit combustion through depleting free radicals' concentration in the homogeneous phase.

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Section: Numerical Performance Of Reduced Mechanismmentioning

confidence: 99%

mentioning

confidence: 98%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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The Heterogeneous and Homogeneous Combustion of Methane Over Inert Particles

Sotudeh‐Gharebagh

Chaouki

2003

Can J Chem Eng

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Fluidized Bed Combustion of Natural Gas and other Hydrocarbons

Laviolette

Sotudeh‐Gharebagh

Mabrouk

et al. 2010

Handbook of Combustion

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The sections in this article are Introduction Heterogeneous and Homogeneous Kinetics Mixing in Gas/Solid Fluidized Beds Mixing Fluidized Bed Combustion Fluidized Bed Combustion Modeling Heterogeneous and Homogeneous Kinetics Homogeneous Kinetics Global Homogeneous Combustion Kinetics Microkinetic Combustion Models Reduced GRI Mechanism Combined Homogeneous and Heterogeneous Kinetics Inert Particles Kinetics for Methane Combustion in Inert Particles Combustion Catalysts Oxygen Carriers Mixing in Gas/Solid Fluidized Beds Superficial Gas Velocity and Bubble Size Particle Size Effect of Baffles Sparger Flow Pattern for Non‐Premixed Operation Methane Fluidized Bed Combustion Inert Particles Fluidized Bed Temperature Bubble Size and Air‐to‐Fuel Ratio Fluidization Regime CO Formation NO x Formation Particle Type and Size Combustion Catalysts Oxygen Carriers/Chemical‐Looping Combustion Fluidized Bed Combustion Modeling Single‐Phase Models Two‐Phase Models Model of D avidson and H arrison Bubbling Bed Models Bubble Assemblage Models Multiple Region Models Kinetic Models

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