Artykuły w czasopismach: „Natural gas-oxidizer; Laminar burning velocity”

1

Han, Zhiqiang, Zhennan Zhu, Peng Wang, Kun Liang, Zinong Zuo i Dongjian Zeng. "The Effect of Initial Conditions on the Laminar Burning Characteristics of Natural Gas Diluted by CO2". Energies 12, nr 15 (27.07.2019): 2892. http://dx.doi.org/10.3390/en12152892.

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The initial conditions such as temperature, pressure and dilution rate can have an effect on the laminar burning velocity of natural gas. It is acknowledged that there is an equivalent effect on the laminar burning velocity between any two initial conditions. The effects of initial temperatures (323 K–423 K), initial pressures (0.1 MPa–0.3 MPa) and dilution rate (0–16%, CO2 as diluent gas) on the laminar burning velocity and the flame instability were investigated at a series of equivalence ratios (0.7–1.2) in a constant volume chamber. A chemical kinetic simulation was also conducted to calculate the laminar burning velocity and essential radicals’ concentrations under the same initial conditions. The results show that the laminar burning velocity of natural gas increases with initial temperature but decreases with initial pressure and dilution rate. The maximum concentrations of H, O and OH increase with initial temperature but decrease with initial pressure and dilution rate. Laminar burning velocity is highly correlated with the sum of the maximum concentration of H and OH.

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Wu, Xueshun, Peng Wang, Zhennan Zhu, Yunshou Qian, Wenbin Yu i Zhiqiang Han. "The Equivalent Effect of Initial Condition Coupling on the Laminar Burning Velocity of Natural Gas Diluted by CO2". Energies 14, nr 4 (4.02.2021): 809. http://dx.doi.org/10.3390/en14040809.

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Initial temperature has a promoting effect on laminar burning velocity, while initial pressure and dilution rate have an inhibitory effect on laminar burning velocity. Equal laminar burning velocities can be obtained by initial condition coupling with different temperatures, pressures and dilution rates. This paper analysed the equivalent distribution pattern of laminar burning velocity and the variation pattern of an equal weight curve using the coupling effect of the initial pressure (0.1–0.3 MPa), initial temperature (323–423 K) and dilution rate (0–16%). The results show that, as the initial temperature increases, the initial pressure decreases and the dilution rate decreases, the rate of change in laminar burning velocity increases. The equivalent effect of initial condition coupling can obtain equal laminar burning velocity with an dilution rate increase (or decrease) of 2% and an initial temperature increase (or decrease) of 29 K. Moreover, the increase in equivalence ratio leads to the rate of change in laminar burning velocity first increasing and then decreasing, while the increases in dilution rate and initial pressure make the rate of change in laminar burning velocity gradually decrease and the increase in initial temperature makes the rate of change in laminar burning velocity gradually increase. The area of the region, where the initial temperature influence weight is larger, gradually decreases as the dilution rate increases, and the rate of decrease gradually decreases.

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Jones, A. L., i R. L. Evans. "Comparison of Burning Rates in a Natural-Gas-Fueled Spark Ignition Engine". Journal of Engineering for Gas Turbines and Power 107, nr 4 (1.10.1985): 908–13. http://dx.doi.org/10.1115/1.3239835.

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A series of tests was conducted on a Toyota, four-cylinder, spark ignition engine which was modified to run on either gasoline or natural gas. The aim of the experiment was to investigate the performance and combustion behavior of natural gas, with particular emphasis on its low burning velocity. A pressure transducer installed in the cylinder head was used to obtain pressure versus crank angle curves from which mass burn rates and burning velocities were calculated, using a heat release analysis program. Results indicate that the low laminar burning velocity of natural gas extends its ignition delay period (time to 1 percent burned) by up to 100 percent compared with gasoline. This contrasts with the remainder of the combustion period which is dominated by turbulence effects that produce very similar burning velocities for the two fuels.

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Cardona Vargas, Arley, Carlos E. Arrieta, Hernando Alexander Yepes Tumay, Camilo Echeverri-Uribe i Andrés Amell. "Determination of laminar burning velocity of methane/air flames in sub atmospheric environments". EUREKA: Physics and Engineering, nr 4 (23.07.2021): 50–62. http://dx.doi.org/10.21303/2461-4262.2021.001775.

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The global energy demand enhances the environmental and operational benefits of natural gas as an energy alternative, due to its composition, mainly methane (CH4), it has low polluting emissions and benefits in energy and combustion systems. In the present work, the laminar burning velocity of methane was determined numerically and experimentally at two pressure conditions, 0.85 atm and 0.98 atm, corresponding to the city of Medellín and Caucasia, respectively, located in Colombia. The environmental conditions were 0.85 atm, 0.98 atm, and 295±1 K. The simulations and experimental measurements were carried out for different equivalence relations. Experimental laminar burning velocities were determined using the burner method and spontaneous chemiluminescence technique, flames were generated using burners with contoured rectangular ports to maintain laminar Reynolds numbers for the equivalence ratios under study and to reduce the effects of stretch and curvature in the direction of the burner's axis. In general, the laminar burning velocity fits well with the numerical results. With the results obtained, a correlation is proposed that relates the laminar burning velocity with the effects of pressure, in the form SL=aPb, where a and b are model constants. Sensitivity analysis was performed using the GRI-Mech 3.0 mechanism which showed that the most sensitive reaction was H+O2=O+OH (R38). Additionally, it was found that the reactions H+CH3 (+M)=CH4 (+M) (R52), 2CH3 (+M)=C2H6 (+M) (R158), and O+CH3=H+CH2O (R10) dominate the consumption of CH3 which is an important radical in the oxidation of methane, this analysis is carried out for equivalence ratios of 0.8 and 1.0, and atmospheric pressures of 0.85 atm and 0.98 atm

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Zhang, Ziyue, Runfan Zhu, Yanqun Zhu, Wubin Weng, Yong He i Zhihua Wang. "Experimental and Kinetic Study on Laminar Burning Velocities of High Ratio Hydrogen Addition to CH4+O2+N2 and NG+O2+N2 Flames". Energies 16, nr 14 (9.07.2023): 5265. http://dx.doi.org/10.3390/en16145265.

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In 2020, energy-related CO2 emissions reached 31.5 Gt, leading to an unprecedented atmospheric CO2 level of 412.5 ppm. Hydrogen blending in natural gas (NG) is a solution for maximizing clean energy utilization and enabling long-distance H2 transport through pipelines. However, insufficient comprehension concerning the combustion characteristics of NG, specifically when blended with a high proportion of hydrogen up to 80%, particularly with minority species, persists. Utilizing the heat flux method at room temperature and 1 atm, this experiment investigated the laminar burning velocities of CH4/NG/H2/air/He flames incorporating minority species, specifically C2H6 and C3H8, within NG. The results point out the regularity of SL enhancement, reaching its maximum at an equivalence ratio of 1.4. Furthermore, the propensity for the enhancement of laminar burning velocity aligned with the observed thermoacoustic oscillation instability during fuel-rich regimes. The experimental findings were contrasted with kinetic simulations, utilizing the GRI 3.0 and San Diego mechanisms to facilitate analysis. The inclusion of H2 augments the chemical reactions within the preheating zone, while the thermal effect from temperature is negligible. Both experimental and simulated results revealed that CH4 and NG with a large proportion of H2 had no difference, no matter whether from a laminar burning velocity or a kinetic analysis aspect.

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Sanmiguel, Javier E., S. A. (Raj) Mehta i R. Gordon Moore. "An Experimental Study of Controlled Gas-Phase Combustion in Porous Media for Enhanced Recovery of Oil and Gas". Journal of Energy Resources Technology 125, nr 1 (1.03.2003): 64–71. http://dx.doi.org/10.1115/1.1510522.

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This paper describes an experimental study aimed at establishing fundamental information on the various processes and relevant controlling mechanisms associated with gas-phase combustion in porous media, especially at elevated pressures. A novel apparatus has been designed, constructed and commissioned in order to evaluate the effects of controlling parameters such as operating pressure, gas flow rate, type and size of porous media, and equivalence ratio on combustion characteristics. The results of this study, concerned with lean mixtures of natural gas and air and operational pressures from atmospheric (88.5 kPa or 12.8 psia) to 433.0 kPa (62.8 psia), will be presented. It will be shown that the velocity of the combustion front decreases as the operating pressure of the system increases, and during some test operating conditions, the apparent burning velocities are over 40 times higher than the open flame laminar burning velocities.

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Kro¨ner, M., J. Fritz i T. Sattelmayer. "Flashback Limits for Combustion Induced Vortex Breakdown in a Swirl Burner". Journal of Engineering for Gas Turbines and Power 125, nr 3 (1.07.2003): 693–700. http://dx.doi.org/10.1115/1.1582498.

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Flame flashback from the combustion chamber into the mixing zone limits the reliability of swirl stabilized lean premixed combustion in gas turbines. In a former study, the combustion induced vortex breakdown (CIVB) has been identified as a prevailing flashback mechanism of swirl burners. The present study has been performed to determine the flashback limits of a swirl burner with cylindrical premixing tube without centerbody at atmospheric conditions. The flashback limits, herein defined as the upstream flame propagation through the entire mixing tube, have been detected by a special optical flame sensor with a high temporal resolution. In order to study the effect of the relevant parameters on the flashback limits, the burning velocity of the fuel has been varied using four different natural gas-hydrogen-mixtures with a volume fraction of up to 60% hydrogen. A simple approach for the calculation of the laminar flame speeds of these mixtures is proposed which is used in the next step to correlate the experimental results. In the study, the preheat temperature of the fuel mixture was varied from 100°C to 450°C in order to investigate influence of the burning velocity as well as the density ratio over the flame front. Moreover, the mass flow rate has been modified in a wide range as an additional parameter of technical importance. It was found that the quenching of the chemical reaction is the governing factor for the flashback limit. A Peclet number model was successfully applied to correlate the flashback limits as a function of the mixing tube diameter, the flow rate and the laminar burning velocity. Using this model, a quench factor can be determined for the burner, which is a criterion for the flashback resistance of the swirler and which allows to calculate the flashback limit for all operating conditions on the basis of a limited number of flashback tests.

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8

El-Sherif, A. S. "Effects of natural gas composition on the nitrogen oxide, flame structure and burning velocity under laminar premixed flame conditions". Fuel 77, nr 14 (listopad 1998): 1539–47. http://dx.doi.org/10.1016/s0016-2361(98)00083-0.

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Mehra, Roopesh Kumar, Hao Duan, Sijie Luo i Fanhua Ma. "Laminar burning velocity of hydrogen and carbon-monoxide enriched natural gas (HyCONG): An experimental and artificial neural network study". Fuel 246 (czerwiec 2019): 476–90. http://dx.doi.org/10.1016/j.fuel.2019.03.003.

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Mitu, Maria, Domnina Razus i Volkmar Schroeder. "Laminar Burning Velocities of Hydrogen-Blended Methane–Air and Natural Gas–Air Mixtures, Calculated from the Early Stage of p(t) Records in a Spherical Vessel". Energies 14, nr 22 (12.11.2021): 7556. http://dx.doi.org/10.3390/en14227556.

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The flammable hydrogen-blended methane–air and natural gas–air mixtures raise specific safety and environmental issues in the industry and transportation; therefore, their explosion characteristics such as the explosion limits, explosion pressures, and rates of pressure rise have significant importance from a safety point of view. At the same time, the laminar burning velocities are the most useful parameters for practical applications and in basic studies for the validation of reaction mechanisms and modeling turbulent combustion. In the present study, an experimental and numerical study of the effect of hydrogen addition on the laminar burning velocity (LBV) of methane–air and natural gas–air mixtures was conducted, using mixtures with equivalence ratios within 0.90 and 1.30 and various hydrogen fractions rH within 0.0 and 0.5. The experiments were performed in a 14 L spherical vessel with central ignition at ambient initial conditions. The LBVs were calculated from p(t) data, determined in accordance with EN 15967, by using only the early stage of flame propagation. The results show that hydrogen addition determines an increase in LBV for all examined binary flammable mixtures. The LBV variation versus the fraction of added hydrogen, rH, follows a linear trend only at moderate hydrogen fractions. The further increase in rH results in a stronger variation in LBV, as shown by both experimental and computed LBVs. Hydrogen addition significantly changes the thermal diffusivity of flammable CH4–air or NG–air mixtures, the rate of heat release, and the concentration of active radical species in the flame front and contribute, thus, to LBV variation.

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11

Miao, Haiyan, Min Ji, Qi Jiao, Qian Huang i Zuohua Huang. "Laminar burning velocity and Markstein length of nitrogen diluted natural gas/hydrogen/air mixtures at normal, reduced and elevated pressures". International Journal of Hydrogen Energy 34, nr 7 (kwiecień 2009): 3145–55. http://dx.doi.org/10.1016/j.ijhydene.2009.01.059.

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Joo, S., S. Kwak, S. Kim, J. Lee i Y. Yoon. "High-frequency transition characteristics of synthetic natural gas combustion in gas turbine". Aeronautical Journal 123, nr 1259 (styczeń 2019): 138–56. http://dx.doi.org/10.1017/aer.2018.150.

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AbstractIn this study, the combustion instability and emission characteristics of flames of different H2/CH4 compositions were investigated in a partially premixed model gas turbine combustor. A mode shift in the frequency of instability occurred under varying experimental conditions from the first to the seventh mode of longitudinal frequency in the combustor, and a parametric study was conducted to determine the reasons for this shift by using the length of the combustor, a factor that determines the mode frequency of longitudinal instability, as the main parameter. Furthermore, heat load and fuel composition (H2 ratio) were considered as parameters to compare the phenomenon under different conditions. The GRI-3.0 CANTERA code, OH chemiluminescence and the Abel inversion process were applied to analyse the frequency mode shift. NOx emissions, which occurred through the thermal NOx mechanism, increased with increasing heat load and H2 ratio. The instability frequency shifted from the first to the seventh mode as the H2 ratio increased in the H2/CH4 mixture. However, 100% H2 as fuel did not cause combustion instability because it has a higher burning velocity and extinction stretch rate than CH4. Furthermore, the laminar flame speed influenced the frequency mode shift. These phenomena were confirmed by the flame shapes. The Abel inversion process was applied to obtain the cross section of the flames from averaged OH chemiluminescence images. Stable and unstable flames were identified from the radial profile of OH concentration. The combustor length was found to not influence frequency mode shift, whereas the H2 ratio significantly influenced it as well as the flame shape. The results of this experimental study can help in the reliable operation of gas turbine systems in SNG plants.

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Khan, A. R., M. R. Ravi i Anjan Ray. "Experimental and Numerical Study of the Effect of Higher Hydrocarbon Content on Laminar Burning Velocity and Flame Stability of Natural Gas". Combustion Science and Technology 192, nr 2 (28.01.2019): 359–90. http://dx.doi.org/10.1080/00102202.2019.1565532.

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Yasiry, Ahmed, Jinhua Wang, Longkai Zhang, Hongchao Dai, Ahmed A. A. Abdulraheem, Haroun A. K. Shahad i Zuohua Huang. "Experimental Study on the Effect of Hydrogen Addition on the Laminar Burning Velocity of Methane/Ammonia–Air Flames". Applied Sciences 13, nr 10 (9.05.2023): 5853. http://dx.doi.org/10.3390/app13105853.

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Variations in methane–ammonia blends with hydrogen enrichment can modify premixed flame behavior and play a crucial role in achieving ultra-low carbon emissions and sustainable energy consumption. Current combustion units may co-fire ammonia/methane/hydrogen, necessitating further investigation into flame characteristics to understand the behavior of multi-component fuels. This research aims to explore the potential of replacing natural gas with ammonia while making only minor adjustments to equipment and processes. The laminar burning velocity (LBV) of binary blends, such as ammonia–methane, ammonia–hydrogen, and hydrogen–methane–air mixtures, was investigated at an equivalence ratio of 0.8–1.2, within a constant volume combustion chamber at a pressure of 0.1 MPa and temperature of 298 K. Additionally, tertiary fuels were examined with varying hydrogen blending ratios ranging from 0% to 40%. The results show that the laminar burning velocity (LBV) increases as the hydrogen fraction increases for all mixtures, while methane increases the LBV during blending with ammonia. Hydrogen-ammonia blends are the most effective mixture for increasing LBV non-linearly. Enhancement parameters demonstrate the effect of ternary fuel, which behaves similarly to equivalent methane in terms of adiabatic flame temperature and LBV achieved at 40% hydrogen. Experimental data for neat and binary mixtures were validated by different kinetics models, which also showed good consistency. The ternary fuel mixtures were also validated with these models. The Li model may qualitatively predict well for ammonia-dominated fuel. The Shrestha model may overestimate results on the rich side due to the incomplete N2Hisub-mechanism, while lean and stoichiometric conditions have better predictions. The Okafor model is always overestimated.

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Baumgärtner, Max H., i Thomas Sattelmayer. "Improvement of the turn-down ratio of gas turbines by autothermal on board syngas generation". Journal of the Global Power and Propulsion Society 1 (30.06.2017): D0HPA5. http://dx.doi.org/10.22261/d0hpa5.

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Abstract The low reactivity of natural gas leads to a sudden increase of carbon monoxide (CO) and unburned hydrocarbons (UHC) emissions below a certain load level, which limits the part load operation range of current utility gas turbines in combined cycle power plants (CCPP). The feasibility of catalytic autothermal syngas generation directly upstream of gas turbine burners to improve burn-out at low flame temperatures is studied in this paper. The adiabatic reformer is supplied with a mixture of natural gas, air and water and generates syngas with high reactivity, which results in better low-temperature combustion performance. Substitution of part of the natural gas by syngas provides the opportunity of lowering overall equivalence ratio in the combustion chamber and of extending the operation range towards lower minimum power output without violating emission limits. A generic gas turbine with a syngas generator is modelled by analytic equations to identify the possible operating window of a fuel processor constrained by pressure loss, low and high temperature limits and carbon formation. A kinetic study shows good conversion of methane to syngas with a high hydrogen share. A calculation of the one-dimensional laminar burning velocity of mixtures of syngas and methane and the assessment of the corresponding Damköhler number show the potential for lowering the minimum equivalence ratio with full burn-out by fuel processing. The study shows that such a fuel processor has a possible operating range despite the before mentioned constraints and it has potential to reduce the lowest possible load of gas turbines in terms of thermal power by 20%.

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Khan, A. R., M. R. Ravi i Anjan Ray. "Experimental and chemical kinetic studies of the effect of H2 enrichment on the laminar burning velocity and flame stability of various multicomponent natural gas blends". International Journal of Hydrogen Energy 44, nr 2 (styczeń 2019): 1192–212. http://dx.doi.org/10.1016/j.ijhydene.2018.10.207.

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Morovatiyan, Mohammadrasool, Martia Shahsavan, Mammadbaghir Baghirzade i J. Hunter Mack. "Impact of Syngas Addition to Methane On Laminar Burning Velocity". Journal of Engineering for Gas Turbines and Power, 6.11.2020. http://dx.doi.org/10.1115/1.4049012.

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Abstract Exhaust gas recirculation (EGR) in spark-ignited engines is a key technique to reduce in-cylinder NOx production by decreasing the combustion temperature. The major species of the exhaust gas in rich combustion of natural gas are hydrogen and carbon monoxide, which can subsequently be recirculated to the cylinders using EGR. In this study, the effect of hydrogen and carbon monoxide addition to methane on laminar burning velocity and flame morphological structure is investigated. Due to the broad flammability limit and high burning velocity of hydrogen compared to methane, this addition to the gaseous mixture leads to an increase in burning velocity, less emissions production, and a boost to the thermal efficiency of internal combustion engines. Premixed CH4-H2-CO-Air flames are experimentally investigated using an optically accessible constant volume combustion chamber (CVCC) accompanied with a high-speed Z-type Schlieren imaging system. Furthermore, a numerical code is applied to quantify the laminar burning velocity based on the pressure rise during flame propagation within the CVCC. According to the empirical and numerical results, the addition of hydrogen and carbon monoxide enhances laminar burning velocity while influencing the flame structure and development.

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"99/01447 Effects of natural gas composition on the nitrogen oxide, flame structure and burning velocity under laminar premixed flame conditions". Fuel and Energy Abstracts 40, nr 2 (marzec 1999): 146. http://dx.doi.org/10.1016/s0140-6701(99)96628-6.

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Yepes, Hernando Alexander, Arley Cardona Vargas i Andrés Amell Arrieta. "Kinetic study of the effect of sub-atmospheric conditions on the laminar burning velocity of high C₂H₆ content natural gas mixtures". Combustion Theory and Modelling, 3.01.2022, 1–27. http://dx.doi.org/10.1080/13647830.2021.2016981.

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Subash, Arman Ahamed, Haisol Kim, Sven-Inge Möller, Mattias Richter, Christian Brackmann, Marcus Aldén, Andreas Lantz, Annika Lindholm, Jenny Larfeldt i Daniel Lörstad. "Investigation of Fuel and Load Flexibility in a Siemens Gas Turbine-600/700/800 Burner Under Atmospheric Pressure Conditions Using High-Speed Hydroxyl-PLIF and Hydroxyl Radical Chemiluminescence Imaging". Journal of Engineering for Gas Turbines and Power 143, nr 8 (31.03.2021). http://dx.doi.org/10.1115/1.4049499.

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Abstract Fuel and load flexibility have been increasingly important features of industrial gas turbines in order to meet the demand for increased utilization of renewable fuels and to provide a way to balance the grid fluctuations due to the unsteady supply of wind and solar power. Experimental investigations were performed using a standard third-generation dry low emission (DLE) burner under atmospheric pressure conditions to study the effect of central and pilot fuel addition, load variations, and hydrogen (H2) enrichment in a natural gas (NG) flame. High-speed kHz planar laser-induced fluorescence (PLIF) of OH radicals and imaging of OH chemiluminescence were employed to investigate the flame stabilization, flame turbulence interactions, and flame dynamics. Along with the optical measurements, combustion emissions were also recorded to observe the effect of changing operating conditions on NOX level. The burner is used in Siemens industrial gas turbines SGT-600, SGT-700, and SGT-800 with minor hardware differences and the study thus is a step to characterize fuel and load flexibility for these turbines. Without pilot and central fuel injections in the current burner configuration, the main flame is stabilized creating a central recirculation zone (CRZ). Addition of the pilot fuel strengthens the outer recirculation zone (ORZ) and moves the flame anchoring position slightly downstream, whereas the flame moves upstream without affecting the ORZ when central fuel injection is added. The flame was investigated utilizing H2/NG fuel mixtures where the H2 amount was changed from 0 to 100%. The results show that the characteristics of the flames are clearly affected by the addition of H2 and by the load variations. The flame becomes more compact, the anchoring position moves closer to the burner exit and the OH signal distribution becomes more distinct for H2 addition due to increased reaction rate, diffusivity, and laminar burning velocity. Changing the load from part to base, similar trends were observed in the flame behavior but in this case due to the higher heat release because of increased turbulence intensity.

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Artykuły w czasopismach na temat „Natural gas-oxidizer; Laminar burning velocity”

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