Effects of Fuel-Side Nitrogen Dilution on Structure and NOx Formation of Turbulent Syngas Non-premixed Jet Flames

2012 ◽  
Vol 26 (6) ◽  
pp. 3304-3315 ◽  
Author(s):  
Jeongwon Lee ◽  
Sangwoon Park ◽  
Yongmo Kim
Keyword(s):  
Jet Flames ◽  
Nox Formation ◽  
Nitrogen Dilution

Nitrogen-Diluted Methane Flames in the Near-and Far-Field

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
James Kribs ◽  
Nancy Moore ◽  
Tamir Hasan ◽  
Kevin Lyons
Keyword(s):  
Reynolds Number ◽  
Natural Gas ◽  
Low Reynolds Number ◽  
Industrial Applications ◽  
Flame Height ◽  
Far Field ◽  
Jet Flames ◽  
Jet Flame ◽  
Lifted Flame ◽  
Nitrogen Dilution

With the increased utilization of multicomponent fuels, such as natural gas and biogas, in industrial applications, there is a need to be able to effectively model and predict the properties of jet flames for mixed fuels. In addition, the interaction of these diluted fuels with outside influences (such as differing levels of coflow air) is a primary consideration. Experiments were performed on methane jet flames under the influence of varying levels of nitrogen dilution, from low Reynolds number lifted regimes to blowout, observing the influence of the nitrogen on lifted flame height and flame chemiluminesence images. These findings were analyzed and compared with existing lifted jet flame relations, such as the flammable region approximation proposed by Tieszen et al., as well as to undiluted flames. The influence of nitrogen dilution was seen to have an effect on the liftoff height of the flame, as well as the blowout velocity of the flame, but was seen to have a less pronounced effect compared with flames with coflowing air.

Experimental Observations of Nitrogen Diluted Ethylene and Methane Jet Flames

2013 ◽  
Author(s):  
Andrew R. Hutchins ◽  
James D. Kribs ◽  
Richard D. Muncey ◽  
William A. Reach ◽  
Kevin M. Lyons
Keyword(s):  
Thermal Diffusivity ◽  
Higher Order ◽  
Flame Stabilization ◽  
Hydrocarbon Fuels ◽  
Jet Flames ◽  
Nitrogen Dilution ◽  
Fuel Mixtures ◽  
And Behavior ◽  
Ethylene Flames

While the liftoff mechanisms of nitrogen-diluted methane jet flames have been well documented, higher order fuels, such as ethylene, have not been studied as extensively with regards to flame stabilization and behavior. Higher order fuels generally burn more intensely, and thus produce much different stabilization patterns than those of simple hydrocarbon fuels, such as methane. The purpose of this study was to observe the effects of nitrogen dilution on ethylene combustion and compare to that witnessed in typical methane jet flames; specifically, the influence on the liftoff height, blowout, and flame chemiluminescence. Liftoff and blowout velocities were compared for various mixtures of ethylene without nitrogen. It was observed that the reason behind the varying stabilization patterns is due to the higher thermal diffusivity of ethylene as well the higher flame speeds that are characterized in the combustion of ethylene. Using a sequence of images from each mixture, the flame liftoff heights were recorded. Due to the strong chemiluminescence of ethylene flames, little fluctuation between liftoff parameters was observed, with respect the velocity; however, there was a significant effect on the liftoff height, with respect to dilution. Blowout for fuel mixtures was much more difficult to achieve due to the higher thermal diffusivity of ethylene, meaning the flame would stabilize at positions much farther downstream than those of simple hydrocarbon fuels.

Numerical Modeling of a Lifted Laminar Coflow Methane Diffusion Jet Flames Using Detailed Chemistry and Non-Grey Gas Radiation Models

2002 ◽  
Author(s):  
Fengshan Liu ◽  
Hongsheng Guo ◽  
Gregory J. Smallwood
Keyword(s):  
Carbon Dioxide ◽  
Radiation Heat Transfer ◽  
Radiation Absorption ◽  
Discrete Ordinates ◽  
Band Model ◽  
Jet Flames ◽  
Nox Formation ◽  
Model Calculations ◽  
Detailed Chemistry ◽  
Methane Diffusion

Two lifted laminar coflow non-sooting methane diffusion jet flames, one diluted by nitrogen and the other diluted by carbon dioxide, at atmospheric pressure were calculated using detailed chemistry and complex thermal and transport properties. Chemical reactions were modeled using the GRI-Mech 3.0 mechanism with species and reactions related to NOx formation removed. Radiation heat transfer by CO, CO2, and H2O was calculated using the discrete-ordinates method coupled with a statistical narrow-band correlated-k based band model. Calculations of each flame were performed with and without radiation absorption term in the radiative transfer equation in order to provide a quantitative evaluation of the importance of radiation absorption in these two lifted flames. Numerical results show that radiation absorption is relatively unimportant in the nitrogen diluted flame but becomes important in the carbon dioxide diluted flame.

Nitrogen Diluted Jet Flames in the Presence of Coflowing Air

2011 ◽  
Author(s):  
James D. Kribs ◽  
Tamir S. Hasan ◽  
Kevin M. Lyons
Keyword(s):  
Diffusion Flame ◽  
Axial Position ◽  
Flammability Limit ◽  
Jet Flames ◽  
Flow Rates ◽  
Nitrogen Dilution ◽  
Flame Shape ◽  
Methane Flow

The purpose of this study is to observe methane jet flames under varying levels of nitrogen dilution and coflowing air. The jet flames were examined in order to determine the conditions for which liftoff and blowout occur under conditions that strain the flame. Methane flow rates were varied, corresponding to intermediate lifted positions to blowout. A sequence of images were taken at each level of dilution and coflow, and were used to determine the lowest radial and axial position of the flammability limit. These flammability regions were compared to the lean flammability limit. It was observed that flame shape and liftoff were considerably more influenced by the effects of the coflowing air compared to the presence of the diluents, and that flames under coflow lost the trailing diffusion flame earlier, which has been shown to be a marker for flame blowout.

scholarly journals Scaling of Pulverized-Fuel Jet Flames That Apply Large Amounts of Excess Air—Implications for NOx Formation

Energies ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2680 ◽  
Author(s):  
Rikard Edland ◽  
Fredrik Normann ◽  
Thomas Allgurén ◽  
Christian Fredriksson ◽  
Klas Andersson
Keyword(s):  
Pilot Scale ◽  
Jet Flames ◽  
Nox Formation ◽  
Char Combustion ◽  
Ore Pellets ◽  
Excess Air ◽  
Fuel Jet ◽  
Pulverized Fuel ◽  
Rotary Kilns ◽  
Combustion Processes

Measures to reduce nitrogen oxides (NOx) formation in industrial combustion processes often require up-scaling through pilot-scale facilities prior to being implemented in commercial scale, and scaling is therefore an important aspect of achieving lower NOx emissions. The current paper is a combined experimental and modelling study that aims to expand the understanding of constant velocity scaling for industrial jet flames applying high amounts of excess air. These types of flames are found in e.g., rotary kilns for production of iron ore pellets. The results show that, even if the combustion settings, velocity, and temperature profiles are correctly scaled, the concentration of oxygen experienced by the fuel during char combustion will scale differently. As the NO formation from the char combustion is important in these flames, the differences induced by the scaling has important impacts on the efficiencies of the applied primary measures. Increasing the rate of char combustion (to increase the Damköhler number), by using, for example, smaller-sized particles, in the pilot-scale is recommended to improve scaling.

Effects of Diluents on Lifted Turbulent Methane and Ethylene Jet Flames

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
Andrew R. Hutchins ◽  
James D. Kribs ◽  
Kevin M. Lyons
Keyword(s):  
Mole Fraction ◽  
Flame Speed ◽  
Flow Conditions ◽  
Jet Flames ◽  
Nitrogen Dilution ◽  
Potential Impact ◽  
Methane Flames ◽  
Burner Operation ◽  
Jet Velocities ◽  
Ethylene Flames

The effects of diluents on the liftoff of turbulent, partially premixed methane and ethylene jet flames for potential impact in industrial burner operation for multifuel operation have been investigated. Both fuel jets were diluted with nitrogen and argon in separate experiments, and the flame liftoff heights were compared for a variety of flow conditions. Methane flames have been shown to liftoff at lower jet velocities and reach blowout conditions much more rapidly than ethylene flames. Diluting ethylene and methane jets with nitrogen and argon, independently, resulted in varying trends for each fuel. At low dilution levels (∼5% by mole fraction), methane flames were lifted to similar heights, regardless of the diluent type; however, at higher dilution levels (∼10% by mole fraction) the argon diluent produced a flame which stabilized farther downstream. Ethylene jet flames proved to vary less in liftoff heights with respect to diluent type. Significant soot reduction with dilution is witnessed for both ethylene and methane flames, in that flame luminosity alteration occurs at the flame base at increasing levels of argon and nitrogen dilution. The increasing dilution levels also decreased the liftoff velocity of the fuel. Analysis showed little variance among liftoff heights in ethylene flames for the various inert diluents, while methane flames proved to be more sensitive to diluent type. This sensitivity is attributed to the more narrow limits of flammability of methane in comparison to ethylene, as well as the much higher flame speed of ethylene flames.

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