scholarly journals Investigation of the Effect of Hydrogen and Methane on Combustion of Multicomponent Syngas Mixtures using a Constructed Reduced Chemical Kinetics Mechanism

Energies ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 2442 ◽  
Author(s):  
Nearchos Stylianidis ◽  
Ulugbek Azimov ◽  
Martin Birkett
Keyword(s):  
Chemical Kinetics ◽  
Ignition Delay ◽  
Delay Time ◽  
Ignition Delay Time ◽  
High Pressures ◽  
Laminar Flame ◽  
Flame Speed ◽  
Laminar Flame Speed ◽  
The Difference ◽  
Rich Mixtures

This study investigated the effects of H2 and CH4 concentrations on the ignition delay time and laminar flame speed during the combustion of CH4/H2 and multicomponent syngas mixtures using a novel constructed reduced syngas chemical kinetics mechanism. The results were compared with experiments and GRI Mech 3.0 mechanism. It was found that mixture reactivity decreases and increases when higher concentrations of CH4 and H2 were used, respectively. With higher H2 concentration in the mixture, the formation of OH is faster, leading to higher laminar flame speed and shorter ignition delay time. CH4 and H2 concentrations were calculated at different pressures and equivalence ratios, showing that at high pressures CH4 is consumed slower, and, at different equivalence ratios CH4 reacts at different temperatures. In the presence of H2, CH4 was consumed faster. In the conducted two-stage sensitivity analysis, the first analysis showed that H2/CH4/CO mixture combustion is driven by H2-based reactions related to the consumption/formation of OH and CH4 recombination reactions are responsible for CH4 oxidation. The second analysis showed that similar CH4-based and H2 -based reactions were sensitive in both, methane- and hydrogen-rich H2/CH4 mixtures. The difference was observed for reactions CH2O + OH = HCO + H2O and CH4 + HO2 = CH3 + H2O2, which were found to be important for CH4-rich mixtures, while reactions OH + HO2 = H2O + O2 and HO2 + H = OH + OH were found to be important for H2-rich mixtures.

The Influence of Singlet Oxygen and Ozone on the Combustion in Methane-Air Mixture

2013 ◽  
Vol 699 ◽  
pp. 111-118
Author(s):  
Rui Shi ◽  
Chang Hui Wang ◽  
Yan Nan Chang
Keyword(s):  
Singlet Oxygen ◽  
Chemical Kinetics ◽  
Mole Fraction ◽  
Ignition Delay ◽  
Delay Time ◽  
Ignition Delay Time ◽  
Laminar Flame ◽  
Combustion Products ◽  
Flame Speed ◽  
Air Mixing

Based on GRI3.0, we study the main chemical kinetics process about reactions of singlet oxygen O2(a1Δg) and ozone O3 with methane-air combustion products, inherit and further develop research in chemical kinetics process with enhancement effects on methane-air mixed combustion by these two molecules. In addition, influence of these two molecules on ignition delay time and flame speed of laminar mixture are considered in our numerical simulation research. This study validates the calculation of this model which cotains these two active molecules by using experimental data of ignition delay time and the speed of laminar flame propagation. In CH4-air mixing laminar combustion under fuel-lean condition(ф=0.5), flame speed will be increased, and singlet oxygen with 10% of mole fraction increases it by 80.34%, while ozone with 10% mole fraction increase it by 127.96%. It mainly because active atoms and groups(O, H, OH, CH3, CH2O, CH3O, etc) will be increased a lot after adding active molecules in the initial stage, and chain reaction be reacted greatly, inducing shortening of reaction time and accelerating of flame speed. Under fuel rich(ф=1.5), accelerating of flame speed will be weakened slightly, singlet oxygen with 10% in molecular oxygen increase it by 48.93%, while ozone with 10% increase it by 70.25%.

Ignition delay time and laminar flame speed measurements of mixtures containing diisopropyl-methylphosphonate (DIMP)

2020 ◽  
Vol 215 ◽  
pp. 66-77
Author(s):  
Olivier Mathieu ◽  
Travis Sikes ◽  
Waruna D. Kulatilaka ◽  
Eric L. Petersen
Keyword(s):  
Ignition Delay ◽  
Delay Time ◽  
Ignition Delay Time ◽  
Laminar Flame ◽  
Flame Speed ◽  
Laminar Flame Speed

Ignition Delay Time and Laminar Flame Speed Calculations for Natural Gas/Hydrogen Blends at Elevated Pressures

2012 ◽  
Author(s):  
Marissa Brower ◽  
Eric Petersen ◽  
Wayne Metcalfe ◽  
Henry J. Curran ◽  
Marc Füri ◽  
...  
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Chemical Kinetics ◽  
Ignition Delay ◽  
Ignition Delay Time ◽  
Laminar Flame ◽  
Turbulent Flame ◽  
Flame Speed ◽  
Laminar Flame Speed ◽  
Hydrogen Addition

Applications of natural gas and hydrogen co-firing have received increased attention in the gas turbine market, which aims at higher flexibility due to concerns over the availability of fuels. While much work has been done in the development of a fuels database and corresponding chemical kinetics mechanism for natural gas mixtures, there are nonetheless few if any data for mixtures with high levels of hydrogen at conditions of interest to gas turbines. The focus of the present paper is on gas turbine engines with primary and secondary reaction zones as represented in the Alstom and Rolls Royce product portfolio. The present effort includes a parametric study, a gas turbine model study, and turbulent flame speed predictions. Using a highly optimized chemical kinetics mechanism, ignition delay times and laminar burning velocities were calculated for fuels from pure methane to pure hydrogen and with natural gas/hydrogen mixtures. A wide range of engine-relevant conditions were studied: pressures from 1 to 30 atm, flame temperatures from 1600 to 2200 K, primary combustor inlet temperature from 300 to 900 K, and secondary combustor inlet temperatures from 900 to 1400 K. Hydrogen addition was found to increase the reactivity of hydrocarbon fuels at all conditions by increasing the laminar flame speed and decreasing the ignition delay time. Predictions of turbulent flame speeds from the laminar flame speeds show that hydrogen addition affects the reactivity more when turbulence is considered. This combined effort of industrial and university partners brings together the know-how of applied, as well as experimental and theoretical disciplines.

Numerical Study on the Effect of Real Syngas Compositions on Ignition Delay Times and Laminar Flame Speeds at Gas Turbine Conditions

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Olivier Mathieu ◽  
Eric L. Petersen ◽  
Alexander Heufer ◽  
Nicola Donohoe ◽  
Wayne Metcalfe ◽  
...  
Keyword(s):  
Ignition Delay ◽  
Delay Time ◽  
Gas Turbines ◽  
Ignition Delay Time ◽  
Laminar Flame ◽  
Flame Speed ◽  
Operating Conditions ◽  
Laminar Flame Speed ◽  
Ignition Delay Times ◽  
Delay Times

Depending on the feedstock and the production method, the composition of syngas can include (in addition to H2 and CO) small hydrocarbons, diluents (CO2, water, and N2), and impurities (H2S, NH3, NOx, etc.). Despite this fact, most of the studies on syngas combustion do not include hydrocarbons or impurities and in some cases not even diluents in the fuel mixture composition. Hence, studies with realistic syngas composition are necessary to help in designing gas turbines. The aim of this work was to investigate numerically the effect of the variation in the syngas composition on some fundamental combustion properties of premixed systems such as laminar flame speed and ignition delay time at realistic engine operating conditions. Several pressures, temperatures, and equivalence ratios were investigated for the ignition delay times, namely 1, 10, and 35 atm, 900–1400 K, and ϕ = 0.5 and 1.0. For laminar flame speed, temperatures of 300 and 500 K were studied at pressures of 1 atm and 15 atm. Results showed that the addition of hydrocarbons generally reduces the reactivity of the mixture (longer ignition delay time, slower flame speed) due to chemical kinetic effects. The amplitude of this effect is, however, dependent on the nature and concentration of the hydrocarbon as well as the initial condition (pressure, temperature, and equivalence ratio).

scholarly journals Comparative Study on Chemical Kinetics Mechanisms for Methane-Based Fuel Mixtures under Engine-Relevant Conditions

Energies ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2834
Author(s):  
Amin Paykani
Keyword(s):  
Experimental Data ◽  
Natural Gas ◽  
Chemical Kinetics ◽  
Ignition Delay ◽  
High Pressures ◽  
Laminar Flame ◽  
Flame Speed ◽  
Laminar Flame Speed ◽  
Si Engine ◽  
Fuel Blends

The use of natural gas in pure or in a blended form with hydrogen and syngas in spark ignition (SI) engines has received much attention in recent years. They have higher diffusion coefficient and laminar flame speed, a small quenching distance and wider flammability limit which compensate the demerits of the lean-burn natural gas combustion. Therefore, a careful examination of the chemical kinetics of combustion of gaseous fuel blends is of great importance. In this paper, performance of the various chemical kinetics mechanisms is compared against experimental data, accumulated for methane-based fuel blends under engine-relevant conditions to find the most appropriate mechanism in engine simulations. Pure methane, methane/syngas, and methane/propane blends are mainly studied at various temperatures, pressures, and equivalence ratios. The ignition delay time and laminar flame speed are used as quantitative metrics to compare the simulation results with the data from experiments. The mechanisms were shown to be mainly consistent with the experimental data of lean and stoichiometric mixtures at high pressures. It was also shown that the GRI-3.0 and 290Rxn mechanisms have high compatibility with the ignition delay times and laminar flame speed at high pressures and lean conditions, and they can be utilized for simulations of SI engine combustion due to their lower computational cost. The results of present research provide an important contribution to the methane-based fuel blends combustion simulation under SI engine-relevant conditions.

The Effect of Impurities on Ignition Delay Times and Laminar Flame Speeds of Syngas Mixtures at Gas Turbine Conditions

2014 ◽  
Author(s):  
Olivier Mathieu ◽  
Joshua W. Hargis ◽  
Eric L. Petersen ◽  
John Bugler ◽  
Henry J. Curran ◽  
...  
Keyword(s):  
Ignition Delay ◽  
Delay Time ◽  
Gas Turbines ◽  
Ignition Delay Time ◽  
Laminar Flame ◽  
Flame Speed ◽  
Operating Conditions ◽  
Laminar Flame Speed ◽  
Ignition Delay Times ◽  
Combustion Properties

In addition to mostly H2 and CO, syngas also contains reasonable amounts of light hydrocarbons, CO2, H2O, N2, and Ar. Impurities such as NH3, HCN, COS, H2S, and NOx (NO, NO2, N2O) are also commonly found in syngas. The presence of these impurities, even in very low concentrations, can induce some large changes in combustion properties. Although they introduce potential design and operational issues for gas turbines, these changes in combustion properties due to the presence of impurities are still not well characterized. The aim of this work was therefore to investigate numerically the effect of the presence of impurities in realistic syngas compositions on some fundamental combustion properties of premixed systems such as laminar flame speed and ignition delay time, at realistic engine operating conditions. To perform this study, a state-of-the-art C0–C3 detailed kinetics mechanism was used. This mechanism was combined with recent, optimized sub-mechanisms for impurities which can impact the combustion properties of the syngas such as nitrogenous species (i.e., N2O, NO2, NH3, and HCN) and sulfur-based species such as H2S, SO2 and COS. Several temperatures, pressures, and equivalence ratios were investigated. The results of this study showed that the addition of some impurities modifies notably the reactivity of the mixture. The ignition delay time is decreased by the addition of NO2 and H2S at the temperatures and pressures for which the HO2 radical dominates the H2 combustion. However, while NO2 has no effect when OH is dominating, H2S increases the ignition delay time in such conditions for pressures above 1 atm. The amplitude of these effects is however dependent on the impurity concentration. Laminar flame speeds are not sensitive to NO2 addition but they are to NH3 and HCN, inducing a small reduction of the laminar flame speed at fuel rich conditions. H2S exhibits some inhibiting effects on the laminar flame speed but only for high concentrations. The inhibiting effects of NH3, HCN, and H2S are due to the OH radical consumption by these impurities, leading to the formation of radicals that are less reactive.

Ignition Delay Time and Laminar Flame Speed Calculations for Natural Gas/Hydrogen Blends at Elevated Pressures

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Marissa Brower ◽  
Eric L. Petersen ◽  
Wayne Metcalfe ◽  
Henry J. Curran ◽  
Marc Füri ◽  
...  
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Chemical Kinetics ◽  
Ignition Delay ◽  
Ignition Delay Time ◽  
Laminar Flame ◽  
Turbulent Flame ◽  
Flame Speed ◽  
Laminar Flame Speed ◽  
Hydrogen Addition

Applications of natural gas and hydrogen co-firing have received increased attention in the gas turbine market, which aims at higher flexibility due to concerns over the availability of fuels. While much work has been done in the development of a fuels database and corresponding chemical kinetics mechanism for natural gas mixtures, there are nonetheless few if any data for mixtures with high levels of hydrogen at conditions of interest to gas turbines. The focus of the present paper is on gas turbine engines with primary and secondary reaction zones as represented in the Alstom and Rolls Royce product portfolio. The present effort includes a parametric study, a gas turbine model study, and turbulent flame speed predictions. Using a highly optimized chemical kinetics mechanism, ignition delay times and laminar burning velocities were calculated for fuels from pure methane to pure hydrogen and with natural gas/hydrogen mixtures. A wide range of engine-relevant conditions were studied: pressures from 1 to 30 atm, flame temperatures from 1600 to 2200 K, primary combustor inlet temperature from 300 to 900 K, and secondary combustor inlet temperatures from 900 to 1400 K. Hydrogen addition was found to increase the reactivity of hydrocarbon fuels at all conditions by increasing the laminar flame speed and decreasing the ignition delay time. Predictions of turbulent flame speeds from the laminar flame speeds show that hydrogen addition affects the reactivity more when turbulence is considered. This combined effort of industrial and university partners brings together the know-how of applied as well as experimental and theoretical disciplines.

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