The structure of swirl-stabilized turbulent premixed CH4/air and CH4/O2/CO2 flames and mechanisms of intense burning of oxy-flames

Watanabe, Hirotatsu; Shanbhogue, Santosh J.; Taamallah, Soufien; Chakroun, Nadim W.; Ghoniem, Ahmed F.

doi:10.1016/j.combustflame.2016.09.015

Cited by 31 publications

(12 citation statements)

References 31 publications

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“…66,78,[87][88][89][90] Temperature profiles were found to be matched in CH 4 /air and CH 4 / 36%O 2 /64%CO 2 flames, according to Song et al 66 Comparable values were reported in the literature. 59,63,91,92 Rashwan et al 93 reported similar findings; an oxygen fraction of 29% to 40% is needed for stable oxy-combustion with FGR. Moreover, oxy-combustion limits the combustor stability window, because of the negative impact of adding CO 2 on the combustion kinetics.…”

Section: Premixed Oxy-fuel Combustionmentioning

confidence: 68%

“…The adiabatic flame temperature (T ad ) of the reactant mixture was adjusted through the oxygen fraction. 59,63,91,92 Rashwan et al 93 reported similar findings; an oxygen fraction of 29% to 40% is needed for stable oxy-combustion with FGR. The above finding was supported by high-speed images that showed similar vortex collapse modes.…”

Section: Premixed Oxy-fuel Combustionmentioning

confidence: 77%

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Frontiers in combustion techniques and burner designs for emissions control and CO₂capture: A review

et al. 2019

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Summary The use of fossil fuel is expected to increase significantly by midcentury because of the large rise in the world energy demand despite the effective integration of renewable energies in the energy production sector. This increase, alongside with the development of stricter emission regulations, forced the manufacturers of combustion systems, especially gas turbines, to develop novel combustion techniques for the control of NOx and CO2 emissions, the latter being a greenhouse gas responsible for more than 60% to the global warming problem. The present review addresses different burner designs and combustion techniques for clean power production in gas turbines. Combustion and emission characteristics, flame instabilities, and solution techniques are presented, such as lean premixed air‐fuel (LPM) and premixed oxy‐fuel combustion techniques, and the combustor performance is compared for both cases. The fuel flexibility approach is also reviewed, as one of the combustion techniques for controlling emissions and reducing flame instabilities, focusing on the hydrogen‐enrichment and the integrated fuel‐flexible premixed oxy‐combustion approaches. State‐of‐the‐art burner designs for gas turbine combustion applications are reviewed in this study, including stagnation point reverse flow (SPRF) burner, dry low NOx (DLN) and dry low‐emission (DLE) burners, EnVironmental burners (including EV, AEV, and SEV burners), perforated plate (PP) burner, and micromixer (MM) burner. Special emphasis is made on the MM combustor technology, as one of the most recent advances in gas turbines for stable premixed flame operation with wide turndown and effective control of NOx emissions. Since the generation of pure oxygen is prerequisite to oxy‐combustion, oxygen‐separation membranes became of immense importance either for air separation for clean oxy‐combustion applications or for conversion/splitting of the effluent CO2 into useful chemical and energy products. The different carbon‐capture technologies, along with the most recent carbon‐utilization approaches towards CO2 emissions control, are also reviewed.

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Section: Premixed Oxy-fuel Combustionmentioning

confidence: 68%

Section: Premixed Oxy-fuel Combustionmentioning

confidence: 77%

Frontiers in combustion techniques and burner designs for emissions control and CO₂capture: A review

et al. 2019

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“…As a matter of fact, CO 2 has significant effects on flame characteristics, thermal and transport properties, radiation within the reactor, and rates of reaction kinetics. In addition, the concentration of oxygen should not drop below a certain value (higher than 21% by volume) for stable oxy‐flame operation . Based on that, oxy‐flames have their own challenging characteristics and opportunities as compared with air‐combustion …”

Section: Resultsmentioning

confidence: 99%

“…In addition, the concentration of oxygen should not drop below a certain value (higher than 21% by volume) for stable oxy-flame operation. [35][36][37][38][39] Based on that, oxy-flames have their own challenging characteristics and opportunities as compared with air-combustion. [40][41][42][43][44] The longitudinal temperature measurements were conducted downstream of the combustor due to the thermocouple range limitation.…”

Section: Effects Of Co 2 % and Equivalence Ratio On Temperature Dismentioning

confidence: 99%

Experimental and numerical study of oxy‐methane flames in a porous‐plate reactor mimicking membrane reactor operation

2019

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Summary The work investigates the reacting flow field, oxy‐methane flame characteristics and location, and the species distributions in a porous‐plate reactor mimicking the operation of oxygen transport membrane reactors (OTMRs). The study was performed experimentally and numerically considering ranges of operating equivalence ratio, from 0.5 to 1.0, and CO2 concentrations in the total oxidizer flow (O2 and CO2), from 0% to 55% (by Vol). Oxygen was supplied through a slightly pressurized top and bottom chambers to cross the two porous plates to the central chamber, where a premixed mixture of CH4 and CO2 is introduced. ANSYS Fluent 17.1 software was used to solve for conservation and radiative transfer equations in the full three‐dimensional (3‐D) domain. The modified Westbrook‐Dryer (Oxy‐WD) two‐step reduced mechanism for oxy‐methane combustion was adapted for the calculations of chemical kinetics. The captured flame shapes using a high‐speed camera were compared with the calculated ones, and the results showed good agreements. At fixed equivalence ratio, elongated flames were obtained at higher CO2 concentrations due to the increase in the mainstream Reynolds number and reduction in reaction rates, which delays the completeness of combustion. At fixed CO2 concentration, the increase in equivalence ratio resulted in more compact and intense flames. The effective mixing and flame stability resulted in complete fuel conversion under stoichiometric condition. Stable flames were located between the two porous plates at reasonable distance. This perfect flame location prevents the thermal fracture of the membranes and improves their oxygen permeation flux, resulting in better combustion characteristics when the results are projected on the case of OTMRs. This implies efficient and safe applicability of the OTMRs by the condition that membranes can provide sufficient oxygen flux for complete combustion. A warm outer recirculation zone (ORZ) was created beside each porous plate, which helps anchoring the flame at the leading edge of the porous plate. The range of temperature within the ORZ was 800 to 1600 K, which lies in the operability limits of membranes for the case of OTMRs. The effective complete mixing and flame stability resulted in complete fuel conversion under stoichiometric condition. The temperature and species distributions within the reactor are presented in detail over wide ranges of operating conditions. The results recommended the reactor operation under stoichiometric combustion condition based on performance and economic points of views. The results are promising when projected on the application of the OTMRs under oxy‐combustion conditions for clean and efficient energy production.

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“…Watanabe et al [14] found out that the overall average length of oxy-flames is considerably shorter than that of air-flames in a swirl stabilized combustor. Furthermore, other researchers concluded that CO 2 dilution is an effective way to decrease pollutant emissions such as soot and NO x [15,16].…”

mentioning

confidence: 99%

A numerical investigation of CO2 dilution on the thermochemical characteristics of a swirl stabilized diffusion flame

Vakilipour

Tohidi

Al-Zaili

et al. 2019

Appl. Math. Mech.-Engl. Ed.

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The turbulent combustion flow modeling are performed to study the impacts of CO 2 addition to the fuel and oxidizer streams on the thermochemical characteristics of a swirl stabilized diffusion flame SM1. A flamelet approach along with three well-known turbulence models are utilized to model the turbulent combustion flow field. The k−ω SST shows the best agreement with the experimental fields compared to other methods. Then, the k−ω SST is employed to study the effects of CO 2 dilution on the flame structure and strength, temperature distribution, and CO concentration. To determine the chemical effects of CO 2 dilution, a fictitious species is replaced with the regular CO 2 in both fuel and oxidizer streams.The results indicate that the flame temperature is decreased when CO 2 is added to either fuel or oxidizer streams. The flame length reduction is observed at all levels of CO 2 dilution. The H radical concentration indicating the flame strength decreases following by the thermochemical effects of CO 2 dilution processes. In comparison with fictitious species dilution, chemical effects of CO 2 addition enhance CO mass fraction. The numerical simulations show that by increasing the

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The structure of swirl-stabilized turbulent premixed CH4/air and CH4/O2/CO2 flames and mechanisms of intense burning of oxy-flames

Cited by 31 publications

References 31 publications

Frontiers in combustion techniques and burner designs for emissions control and CO₂capture: A review

Frontiers in combustion techniques and burner designs for emissions control and CO₂capture: A review

Experimental and numerical study of oxy‐methane flames in a porous‐plate reactor mimicking membrane reactor operation

A numerical investigation of CO2 dilution on the thermochemical characteristics of a swirl stabilized diffusion flame

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The structure of swirl-stabilized turbulent premixed CH4/air and CH4/O2/CO2 flames and mechanisms of intense burning of oxy-flames

Cited by 31 publications

References 31 publications

Frontiers in combustion techniques and burner designs for emissions control and CO2capture: A review

Frontiers in combustion techniques and burner designs for emissions control and CO2capture: A review

Experimental and numerical study of oxy‐methane flames in a porous‐plate reactor mimicking membrane reactor operation

A numerical investigation of CO2 dilution on the thermochemical characteristics of a swirl stabilized diffusion flame

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Product

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Frontiers in combustion techniques and burner designs for emissions control and CO₂capture: A review

Frontiers in combustion techniques and burner designs for emissions control and CO₂capture: A review