Premixed Gas Flame Burning Velocities of Biomass Gasification Gas

2012 ◽  
Vol 170-173 ◽  
pp. 2448-2453
Author(s):  
Bao Sheng Bai ◽  
Ji Chun Zhang ◽  
Bo Lin
Keyword(s):  
Equivalence Ratio ◽  
Initial Temperature ◽  
Biomass Gasification ◽  
Gas Flame

Discuss the flame burning velocities of biomass gasification gases and the methods of increasing them by calculating and programming through MATLAB. The results display that the flame burning velocities of biomass gasification gases are relatively low, and they increase when adding hydrogen, which has a higher flame burning speed. Satisfying effects are achieved under different equivalence ratios, initial temperatures and pressures. Research shows that flame burning velocities improve with the fraction of hydrogen volume increasing. It also suggests that with the rise of equivalence ratio, the velocities increase first, and then decrease, and they reach the highest when equivalence ratio is stoichiometric; an increase in initial temperature accelerates the burning velocities, while the velocities drop by enhancing the pressures.

Measurements of the Laminar Burning Velocities for Typical Syngas–Air Mixtures at Elevated Pressures

2011 ◽  
Vol 133 (3) ◽  
Author(s):  
Eliseu Monteiro ◽  
Abel Rouboa
Keyword(s):  
Energy Source ◽  
Equivalence Ratio ◽  
Functional Form ◽  
Burning Velocity ◽  
Biomass Gasification ◽  
Producer Gas ◽  
Volume Percentage ◽  
Elevated Pressures ◽  
Syngas Combustion ◽  
Heat Value

In the currently reported work, three typical mixtures of H2, CO, CH4, CO2, and N2 have been considered as representative of the producer gas (syngas) coming from biomass gasification. Syngas is being recognized as a viable energy source worldwide, particularly for stationary power generation. However, there are gaps in the fundamental understand of syngas combustion characteristics, especially at elevated pressures that are relevant to practical combustors. In this work, constant volume spherical expanding flames of three typical syngas compositions resulting from biomass gasification have been employed to measure the laminar burning velocities for pressures ranges between 1.0 and 20 bar tanking into account the stretch effect on burning velocity. Over the ranges studied, the burning velocities are fit by a functional form Su=Su0(T/T0)α(P/P0)β; and the dependencies of α and β upon the equivalence ratio of mixture are also given. Conclusion can be drawn that the burning velocity decreases with the increase of pressure. In opposite, an increase in temperature induces an increase of the burning velocity. The higher burning velocity value is obtained for downdraft syngas. This result is endorsed to the higher heat value, lower dilution and higher volume percentage of hydrogen in the downdraft syngas.

scholarly journals Numerical study of effects of the intermediates and initial conditions on flame propagation in a real homogeneous charge compression ignition engine

2014 ◽  
Vol 18 (1) ◽  
pp. 79-87 ◽  
Author(s):  
Meng Zhang ◽  
Jinhua Wang ◽  
Zuohua Huang ◽  
Norimasa Iida
Keyword(s):  
Equivalence Ratio ◽  
Initial Temperature ◽  
Exhaust Gas Recirculation ◽  
Flame Speed ◽  
Exhaust Gas ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Crank Angle ◽  
Increase Rate ◽  
Gas Recirculation

The premixed flame speed under a small four stock homogeneous charge compression ignition engine, fueled with dimethyl ether, was investigated. The effects of intermediate species, initial temperature, initial pressure, exhaust gas recirculation, and equivalence ratio were studied and compared to the baseline condition. Results show that, under all conditions, the flame speeds calculated without intermediates are higher than those which took the intermediates in consideration. Flame speeds increase with the increase of crank angle. The increase rate is divided into three regions and the increase rate is obviously high in the event of low temperature heat release. Initial temperature and pressure only affect the crank angle of flame speed, but have little influence on its value. Equivalence ratio and exhaust gas recirculation ratio do not only distinctly decrease the flame speed, but also advance the crank angle of flame speed.

scholarly journals Self-consistent estimates of emission factors of carboncontaining pollutants from a typical gas flare

2020 ◽  
Vol 22 (2) ◽  
pp. 135-149
Author(s):  
O.G. Fawole ◽  
X.-M. Cai ◽  
I. Nikolova ◽  
A.R. MacKenzie
Keyword(s):  
Natural Gas ◽  
Froude Number ◽  
Real World ◽  
Equivalence Ratio ◽  
Emission Factors ◽  
Test Case ◽  
Fuel Gas ◽  
Gas Flaring ◽  
Emissions Inventories ◽  
Gas Flame

This study proposes an approach for estimating the emission of soot, carbon monoxide (CO) and carbondioxide (CO ) from a typical gas flare. The estimations depend on the quantity and varying composition of the 2 natural gas, flame dynamics (represented by the fire Froude number, Fr ) and the equivalence ratio, f, of the fuel- f air mixture. Soot emission estimates are presented as a function of fire Froude number for gases used in labbased  test in order to validate the scheme and for two real-world fuel gas compositions. The mass-weighted carbon-hydrogen ratio (C:H) of the fuel gas compositions are 0.25 and 0.29 which are two extreme cases in terms of density. The soot yield of the lab-based test case was scaled up to estimate the soot yield of a full scale flare using the Richardson number as the scaling parameter. When all other variables are held constant at values characteristics of real-world flares, a difference of 16 % in the fuel-gas density, as indicated by the carbonhydrogen ratio, results in an increase of the emission factors (EF) of soot, CO and CO by factors of ~3, ~1.4 2 3 and ~1.7, measured in g/m , respectively. For both fuel gas compositions, the ratio of EF to EF at the fuel- soot CO lean region f < 1) is higher. The ratio lies in the range 0.031 – 0.13 and 0.0012 – 0.0055 for the fuel-lean (f < 1) and fuel-rich (f > 1) regions, respectively. The approach proposed and results obtained may be adopted to generate emissions inventories of emission species associated with gas flaring on regional and global scales. Keywords: gas flaring; soot; natural gas; emission factor; black carbon; equivalence ratio

scholarly journals The adiabatic flame temperature and laminar flame speed of methane premixed flames at varying pressures

2019 ◽  
pp. 220-227
Author(s):  
Ahmad Sakhrieh
Keyword(s):  
Equivalence Ratio ◽  
Initial Temperature ◽  
Laminar Flame ◽  
Flame Temperature ◽  
Flame Speed ◽  
Pressure Increase ◽  
Stoichiometric Ratio ◽  
Laminar Flame Speed ◽  
Adiabatic Flame Temperature ◽  
Percent Increase

This paper studies the influence of equivalence ratio, pressure and initial temperature on adiabatic flame temperature and laminar flame speed of methane-air mixture. The results indicate that adiabatic flame temperature is weakly correlated with pressure. The adiabatic flame temperature increases only by about 50?C as a result of 30 bar pressure increase. The flame speed is inversely proportional to pressure. The maximum adiabatic flame temperature and flame speed occur at the stoichiometric ratio, ?=1. The percent increase in the flame speed was about 400% when the initial temperature of the mixture is increased from 25?C to 425?C.

scholarly journals Characteristics of Ammonia/Hydrogen Premixed Combustion in a Novel Linear Engine Generator

Proceedings ◽  
2020 ◽  
Vol 58 (1) ◽  
pp. 2
Author(s):  
Fangyu Zhang ◽  
Gen Chen ◽  
Dawei Wu ◽  
Tie Li ◽  
Zhifei Zhang ◽  
...  
Keyword(s):  
Ignition Delay ◽  
Equivalence Ratio ◽  
Initial Temperature ◽  
Laminar Flame ◽  
Initial Pressure ◽  
Premixed Combustion ◽  
Combustion Mechanism ◽  
Detailed Chemical Kinetics ◽  
Linear Engine ◽  
Premixed Laminar

In order to support the development of a novel linear engine generator (LEG), the characteristics of ammonia/hydrogen premixed combustion are studied by using a detailed chemical kinetics mechanism. The ammonia combustion mechanism is identified among several mechanisms and validated with published experimental data. A parametric analysis is carried out under LEG typical working conditions to study the effects of equivalence ratio (0.80 – 1.60), hydrogen blending ratio (0.0 – 0.6), initial temperature (300 – 700 K) and initial pressure (1 – 20 bar) on premixed laminar flame speed, ignition delay and key flame species concentrations. It is shown that an equivalence ratio of around 1.10 – 1.20 is beneficial to both ammonia flame stability and lower NOx emission. Ignition delay is reduced with the increase in hydrogen blending ratio, initial temperature and initial pressure. At a certain initial temperature and initial pressure, the effects of hydrogen blending ratio can be negligible for over 50% hydrogen in the fuel. Under higher pressure (>10 bar), the initial pressure has a minor influence on the ignition delay reduction. It is also found that the high-pressure high-temperature environment contributes to reducing NO emission considerably in ammonia/hydrogen combustion, which implies the potential of a low NOx LEG fuelled by ammonia/hydrogen.

Experiments on Lean Blowout and NOx Emissions of a Premixed Trapped Vortex Combustor With High G-Loading

2011 ◽  
Author(s):  
Jong Guen Lee ◽  
Jeffrey P. Armstrong ◽  
Domenic A. Santavicca
Keyword(s):  
Residence Time ◽  
Equivalence Ratio ◽  
Reaction Rates ◽  
Vortex Chamber ◽  
Nox Emissions ◽  
Lower Mass ◽  
Lean Blowout ◽  
Wide Range ◽  
Gas Flame ◽  
Trapped Vortex

The feasibility of a novel combustor concept (‘g-load’ combustion with trapped-vortex chamber) to extend the premixed lean-blowout (LBO) limit and to decrease NOx emissions was experimentally determined in a scaled-modular rig that simulated a commercial 250 kilowatt microturbine combustor. The effect of a wide range of g-load’s (770–5050) on the flame regime was identified. The natural gas flame was found to be stabilized in the trapped-vortex cavity (TVC) when the equivalence ratio was within a certain range near the lean blowout limits. The TVC extended the LBO limits to marginally lower mass-based equivalence ratio levels (5%). The LBO limits were found to decrease as the g-loads decrease and the residence time increases, indicating the increase of flame mixing and reaction rates with respect to g-load is not the reason for the extension of LBO limits. The increase of residence time of mixture in the TVC was the reason for the improvement of LBO limits. The new combustor concept would enable operation at lower equivalence ratios, reducing the NOx emissions as much as much as 30%. It also showed that when the flame is contained in the trapped vortex cavity, NOx is reduced compared to baseline combustion concept without TVC.

scholarly journals The Temperature and Pressure Dependencies of Propagation Characteris-tics for Premixed Laminar Ethanol-Air Flames

2012 ◽  
Vol 6 (1) ◽  
pp. 55-64 ◽  
Author(s):  
S. Y. Liao ◽  
D. L. Zhong ◽  
C. Yang ◽  
X. B. Pan ◽  
C. Yuan ◽  
...  
Keyword(s):  
Equivalence Ratio ◽  
Initial Temperature ◽  
Burning Velocity ◽  
Initial Mixture ◽  
Spark Ignition ◽  
Laminar Burning Velocity ◽  
Propagation Characteristics ◽  
Activation Temperature ◽  
Temperature And Pressure ◽  
Premixed Laminar

Laminar burning velocity is strongly dependent on mixture characteristics, e.g. initial temperature, pressure and equivalence ratio. In this work, spherically expanding laminar premixed flames, freely propagating from a spark ignition source in initially quiescent ethanol-air mixtures, have been imaged and then the laminar burning velocities were obtained at initial temperatures of 358 K to 500K, pressure of 0.1 to 0.2 MPa and equivalence ratio of 0.7 to 1.4. The measured re-sults and literature data on ethanol laminar burning velocities were accumulated, to analyze the effects of initial tempera-ture and pressure on the propagation characteristics of laminar ethanol-air flames. A correlation in the form of ul=ulo(Tu/Tu0)αT (Pu/Pu0)βP , and validated over much wide temperature, pressure and equivalence ratio ranges. The global activation temperatures were determined in terms of the laminar burning mass flux for ethanol-air flames. And the Zel’dovich numbers were estimated as well. The dependencies of global activation temperature and Zel’dovich number on initial mixture pressure, temperature and equivalence ratio were explored. Additionally, an alterna-tive correlation of laminar burning velocities, from the view of theoretical arguments, was proposed on the basis of the de-termined ethanol-air laminar mass burning flux. Good agreements were obtained in its comparison with the literature data.

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