Experimental and Numerical Study of NOx Formation From the Lean Premixed Combustion of CH4 Mixed With CO2 and N2

Fackler, K. Boyd; Karalus, Megan; Novosselov, Igor; Kramlich, John C.; Malte, Philip C.

doi:10.1115/1.4004127

Cited by 39 publications

(12 citation statements)

References 15 publications

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“…One is the reduction in flame temperature due to the dilution in the reactant [14][15][16][17][18][19], which slows the chemical reaction rate and leads to the reduction in laminar flame speed. This suppression effectively reduces the size of the O/H/OH radical pool [22] and suppresses the formation of NOx. With the presence of CO2 in the reactant, CO2 will compete with O2 for H atom via the reaction of CO 4-OH <-> CO2 -I-H. As a consequence, the reaction rate of most significant chain branching reaction H -I-O2 <-^ OH -h O is suppressed [20,21].…”

Section: Introductionmentioning

confidence: 99%

Effect of Change in Fuel Compositions and Heating Value on Ignition and Performance for Siemens SGT-400 Dry Low Emission Combustion System

Liu¹,

Martin²,

Sanderson³

et al. 2013

Journal of Engineering for Gas Turbines and Power

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The influence of changes in fuel composition and heating value on the performance of an industrial gas turbine combustor was investigated. The combustor tested was a single cannular combustor for Siemens SGT-400 13.4 MW dry low emission engine. Ignition, engine starting, emissions, combustion dynamics, and flash back through burner metal temperature monitoring were among the parameters investigated to evaluate the impact of fuel fiexibility on combustor performance. Lean ignition and extinction limits were measured for three fuels with different heat values in term ofWobbe Index (WI): 25, 28.9, and 45 MJISm (natural gas). The test results show that the air fuel ratio at lean ignition/ extinction limits decreases and the margin between the two limits tends to be smaller as fuel heat value decreases. Engine start tests were also performed with a lower heating value fuel and results were found to be comparable to those for engine starting with natural gas. The combustor was further tested in a high pressure air facility at real engine operating conditions with different fuels covering WIsfrom 17.5 to 70MJISm^. The variation in fuel composition and heating value was achieved in a gas mixing plant by blending natural gas with CO2, CO, N2, and H2 (for the fuel with WI lower than natural gas) and CjHg (for the fuel with WI higher than natural gas). Test results show that a benefit in NO^ reduction can be seen for the lower WI fuels without H2 presence in the fuel and there are no adverse impacts on combustor performance except for the requirement of higher fuel supply pressure, however, this can be easily resolved by minor modification through the fuel injection design. Test results for the H2 enriched and higher WI fuels show that NOx, combustion dynamics and flash back have been adversely affected and major change in burner design is required. For the H2 enriched fuel, the effect of CO and H2 on combustor performance was also investigated for the fuels having a fixed WI of 29MJISm^. It is found that H2 dominates the adverse impact on combustor performance. The chemical kinetic study shows that H2 has significant effect on flame speed change and CO has significant effect on flame temperature change. Although the tests were performed on the Siemens SGT-400 combustion system, the results provide gener-al guidance for the challenge of industrial gas turbine burner design for fuel flexibility.

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Section: Introductionmentioning

confidence: 99%

Effect of Change in Fuel Compositions and Heating Value on Ignition and Performance for Siemens SGT-400 Dry Low Emission Combustion System

Liu¹,

Martin²,

Sanderson³

et al. 2013

Journal of Engineering for Gas Turbines and Power

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“…5) δ t along the radial direction. A solid curve calculated using the complementary error function parameterization as C mean = 0 .…”

Section: Mean Flame Brush Locationmentioning

confidence: 98%

“…They found that the reabsorption of emitted radiation due to the presence of CO 2 in fresh gases leads to higher burning velocities and wider extinction limits. Fackler et al [5] suggested that premixed flames diluted with CO 2 produce less NO x due to both a decrease in N 2 concentration and the depletion by CO 2 of radicals participating in NO x formation chemistry.…”

Section: Introductionmentioning

confidence: 99%

“…The non-thermal effects of diluted gases on pollutant reduction in turbulent premixed combustion have drawn attention from several researchers. The addition of CO 2 to the reactant streams plays an important role in modification of premixed combustion characteristics including flame structure, flame speed, and pollutant formation [2][3][4][5] . Le Cong and Dagaut [6] studied the oxidation of methane-based fuels with CO 2 dilution in a jet-stirred reactor for a wide range of equivalence ratios and temperatures.…”

Section: Introductionmentioning

confidence: 99%

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Dual-pump vibrational CARS measurements of temperature and species concentrations in turbulent premixed flames with CO2 addition

Han

Satija

Kim

et al. 2017

Combustion and Flame

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a b s t r a c tA dual-pump vibrational coherent anti-Stokes Raman scattering (DPVCARS) system was applied for simultaneous temperature and species concentration measurements in jet flames on a newly developed piloted axisymmetric reactor assisted turbulent (PARAT) premixed flame burner. Turbulent lean premixed methane/air round jet flames with varying CO 2 dilution were stabilized using an annular flow of hydrogen at the flame base. Carbon dioxide was injected into the fuel stream to simulate effects of dry exhaust gas recirculation (EGR). The flames were operated at a nearly constant Reynolds number, Lewis number, and adiabatic flame temperature to minimize thermal and transport effects. Velocity boundary conditions at the burner exit were measured using particle image velocimetry. Simultaneous temperature and major species concentrations (O 2 and CO 2 ) were measured along the axial direction at the burner centerline and along the radial direction at representative axial locations above the burner. Progress variables calculated based on the temperatures were used to study the mean flame brush thickness and the turbulent burning velocity. Probability density functions (PDFs) of temperature at various locations are presented and discussed. The DPVCARS measurements provide an experimental database including temperature and turbulent burning velocity for combustion model evaluation and validation and demonstrated a strong potential for flame structure investigation with future improvement on spatial resolution and signal to noise ratio. The merits and limitations of vibrational CARS for diagnostics in turbulent premixed combustion are discussed. The results show that flames with CO 2 addition depart from the universal mean flame brush structure, while their RMS fluctuation values at an identical mean temperature collapse with the undiluted flame. The CO 2 addition increases the combustion intensity with a decrease in turbulent burning velocity when minimizing the thermal and transport effects.

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“…The relative importance of the different NOx pathways are determined using the procedure first described in reference 42 . This procedure involves identifying of the key reactions for each of the formation pathways and isolating in turn each of the pathways to determine their contribution to NO and NO2 rates of production at each point in the flame.…”

Section: Nox Formation Pathwaysmentioning

confidence: 99%

Detailed Emissions Prediction for a Turbulent Swirling Nonpremixed Flame

et al. 2014

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This paper describes validation of a previously-described CFD-CRN method (computational fluid dynamics -chemical reactor network) for emissions predictions for the laboratory benchmark TECFLAM S09c flame. It details CFD simulation, solution strategy, validation using, CRN generation, detailed emissions predictions and reaction pathway studies. Steady-state 3D CFD models of a 45° † Corresponding author. Email address: rory.monaghan@nuigalway.ie. Tel: +353(91)494-256. 2 sector of the combustor, employing standard numerical techniques; steady-state k- SST turbulence, P1 radiation, finite-rate eddy-dissipation turbulence-chemistry interaction, and three-step methane combustion mechanism, were created in ANSYS FLUENT v14. Steady-state models were used as they are of interest to industrial researchers, who are often limited to their use by extremely complex geometries. The models differ in their handling of pressure-velocity coupling and discretization of the momentum equation. The solution which uses SIMPLE coupling and second-order upwind discretization of the momentum equation was generally found to give better results. Satisfactory agreement with experimental profiles for velocity, turbulent kinetic energy, temperature, and species mass fractions has been achieved. Some errors are seen in temperature and CO mass fractions at the highest temperatures (T > 2000 K) and are due to the fact that the highly-simplified three-step kinetic mechanism employed due to practical limitations on computational resources, underestimates CO2 dissociation. The results compare satisfactorily with the state-of-the-art. Non-zero concentrations of CO are predicted in the external recirculation zone, which has not been achieved in previous modeling efforts. The validated solution was used as the basis to generate a CRN using the CFD-CRN method.The CFD-CRN method uses user-defined criteria to divide the CFD domain into a set of interconnected perfectly-stirred reactors (PSRs), i.e. a CRN. This CRN is then solved using detailed chemical kinetic mechanisms in the Kinetic Post-Processor (KPPSMOKE) solver. CRN size-independence studies are performed and it is determined that 5000+ PSRs were needed to adequately capture pollutant formation in the complex recirculating flow field. Validation of CFD-CRN predictions of major species show similar accuracy to steady-state CFD simulation, with improvements over state-of-the-art CFD in CO profile predictions. Satisfactory agreement with previously-published experimental NOx contour plots is also seen. The CFD-CRN is used to study NOx formation pathways in the swirling, turbulent environment of the S09c diffusion flame. As expected, NOx is seen to form primarily in the hightemperature internal recirculation zone (IRZ). The prompt pathway is predicted to be of greatest importance in this area. Significant NOx reburning is seen in the low temperature fuel-air jets 3 immediately adjacent to the IRZ. Overall, the prompt pathway is responsible for 77% of NOx leaving the system, with 12% due to the...

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Experimental and Numerical Study of NOx Formation From the Lean Premixed Combustion of CH4 Mixed With CO2 and N2

Cited by 39 publications

References 15 publications

Effect of Change in Fuel Compositions and Heating Value on Ignition and Performance for Siemens SGT-400 Dry Low Emission Combustion System

Effect of Change in Fuel Compositions and Heating Value on Ignition and Performance for Siemens SGT-400 Dry Low Emission Combustion System

Dual-pump vibrational CARS measurements of temperature and species concentrations in turbulent premixed flames with CO2 addition

Detailed Emissions Prediction for a Turbulent Swirling Nonpremixed Flame

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