Experimental Investigation of CH4 and C3H8 Combustion in a Packed Bed Burner

2011 ◽  
Author(s):  
H. B. Gao ◽  
Z. G. Qu ◽  
W. Q. Tao ◽  
T. J. Lu
Keyword(s):  
Equivalence Ratio ◽  
Packed Bed ◽  
Pollutant Emissions ◽  
Flame Stability ◽  
Nox Emissions ◽  
Flame Thickness ◽  
Porous Burner ◽  
Hc Emissions ◽  
The Stability ◽  
Stability Limits

The main object of this work is to investigate combustion in a two-layer packed beds porous burner, in particular, to study the effect of methane and propane on flame stability, pressure drop and pollutant emissions. The equivalence ratio of both methane and propane varied from 0.55 to 0.70. The results indicated that flame stability limits of both methane and propane enlarged with the increasing of equivalence ratio, however, the stability limits of methane is more widely than propane. The macroscopic flame shapes of methane and propane remains approximately the same but the later has a larger flame thickness. The NOx emissions are seen to be increased and the CO decreased with the equivalence ratio, HC emissions firstly decreased and then increased with the equivalence ratio for both methane and propane.

Numerical study of the flame stability of premixed methane–air combustion in a combined porous-free flame burner

2018 ◽  
Vol 233 (4) ◽  
pp. 530-544 ◽  
Author(s):  
Seyed Mohammad Hashemi ◽  
Seyed Abdolmehdi Hashemi
Keyword(s):  
Equivalence Ratio ◽  
Numerical Study ◽  
Flame Stabilization ◽  
Pollutant Emissions ◽  
Pollutant Emission ◽  
Flame Stability ◽  
Emission Analysis ◽  
Porous Burner ◽  
Flame Burner ◽  
Stability Limits

Premixed methane–air combustion process within a combined porous-free flame burner was investigated numerically in the present study. The burner consisted of a perforated porous ceramic pellet forming combination of submerged and free flame zones. Nonequilibrium thermal condition between the gas and solid phases was implemented and governing equations were solved in a two-dimensional model using finite volume method. Detailed chemistry based on reduced GRI 3.0 mechanism with 41 reaction steps and 16 species including NOx mechanisms was utilized to simulate the combustion processes and pollutant emissions. In order to investigate the validation of the implemented numerical model, the burner was manufactured and tested. The predicted results were consistent with the experimental data. Comparison of the combined porous-free flame burner with porous burner showed that the flame stability limits of the combined burner were higher than those of porous burner. Multimode heat transfer within the porous medium was perused and the effect of heat recirculation on the flame stabilization was discussed. Investigation of the effect of pore density on the flame stabilization showed that the lower pore densities were desirable in order to improve the flame stability limits. Pollutant emission analysis proved that the NO concentration increased with increasing the equivalence ratio while the minimum quantity of CO concentration was evaluated at an equivalence ratio of 0.6.

Investigation of the premixed methane–air combustion through the combined porous-free flame burner by numerical simulation

2019 ◽  
Vol 233 (6) ◽  
pp. 773-785 ◽  
Author(s):  
Seyed Mohammad Hashemi ◽  
Seyed Abdolmehdi Hashemi
Keyword(s):  
Porous Medium ◽  
Thermal Efficiency ◽  
Combustion Process ◽  
Stability Limit ◽  
Flame Stability ◽  
The Novel ◽  
Flame Thickness ◽  
Porous Burner ◽  
Flame Burner ◽  
Stability Limits

Combustion process of the premixed methane–air in a novel combined porous-free flame burner was investigated numerically. Two-dimensional model considering nonequilibrium thermal condition between the gas and solid phases was used and the combustion was simulated using reduced GRI 3.0 multistep chemical kinetics mechanism. To examine the validity of the implemented numerical model, the burner was manufactured and tested. Good agreement between the numerical results and experimental data were observed. Thermal flame thickness, flame stability limit, and thermal efficiency were discussed. Multimode heat transfer in the porous medium including convection, radiation, and conduction were quantified and perused. Results showed that the thermal thickness of laminar free flame established in the perforated portion of the burner was considerably less than thickness of submerged flame stabilized in the porous medium. Predicted results suggested that the flame stability limit was augmented in the combined burner compared to the burner with full porous foam. Analyses of the heat balance showed that the thermal efficiency of the combined porous-free flame burner was less than thermal efficiency of the full porous burner. Comparison of the full porous burner with the novel combined porous-free flame burner demonstrated that the combined burner caused higher stability limits and lower thermal efficiencies.

Investigation of Stability Limits of a Premixed Counter Flame

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
H.A. Abdul Wahhab
Keyword(s):  
Equivalence Ratio ◽  
Analytical Study ◽  
Narrow Range ◽  
Flame Stability ◽  
Local Flow ◽  
Fuel Gas ◽  
Liquid Petroleum Gas ◽  
Air Flow Velocity ◽  
The Stability ◽  
Stability Limits

In combustion operations, flame fronts are often spread in an irregular. Therefore, the temperature and flame speed varies along the flame's front and depend on the asymmetry of the composition of the mixture and the conditions of the local flow before the flame, especially this behavior is evident in double counter flames. This paper describes an analytical study of stability limits of premixed counter flame. The investigation is based on experiments carried out to identify the effect of varying the distance between upper and lower burner edges on the stability limits at different equivalence ratio values; liquid petroleum gas (LPG) was used as fuel in experiments. The blow-off limit, disc flame limit, and double flame limit were investigated. Under the change of fuel gas-air flow velocity, in this type of flames, the conical flame is transformed into mushroom-shaped tented flame attached to the widened convex apex in the medial distance between the upper and lower burner edges. The experimental data and numerical analysis obtained show that high-stability for double flame, fuel-rich premixed flame operate over narrow range of equivalence ratio φ from 0.43 to 1.41. The ANSYS 17.0 FLUENT Premixed Flamelet Module with pre-processing was used. The results appear that increasing distance between burner edges decreases the flame stability efficiency. 

Flame Stabilization and Emissions of a Natural Gas/Air Ceramic Porous Burner

2008 ◽  
Vol 47-50 ◽  
pp. 105-108 ◽  
Author(s):  
Neda Djordjevic ◽  
Peter Habisreuther ◽  
Nikolaos Zarzalis
Keyword(s):  
Gas Turbines ◽  
Premixed Flames ◽  
Stability Limit ◽  
Porous Matrix ◽  
Flame Stabilization ◽  
Pollutant Emissions ◽  
Inert Material ◽  
Flame Stability ◽  
Nox Emissions ◽  
Porous Burner

Increasingly stringent regulations for limiting pollutant emissions for both aircraft and industrial gas turbines enforce further reduction of NOx emissions while maintaining flame stability. Application of premixed flames offers the possibility to reduce these emissions, but nevertheless it is strongly connected with flame instability risks. A possible solution to ensure the stability of premixed flames is to provide enhanced heat recirculation employing porous inert material. Experimental determination of flame stability and emissions of a porous burner containing a reticulate ceramic sponge structure are reported and the influence of the structural properties of the porous matrix on stable operating range was investigated. It was found, that the flame stability limit was significantly higher compared with free flame burners and nitric oxide (NOx) emissions were below 10 ppm for all cases.

Intake-Air Oxygen-Enrichment of Diesel Engines as a Power Enhancement Method and Implications on Pollutant Emissions

2009 ◽  
Author(s):  
Theodoros C. Zannis ◽  
Dimitrios T. Hountalas ◽  
Elias A. Yfantis ◽  
Roussos G. Papagiannakis ◽  
Yiannis A. Levendis
Keyword(s):  
Theoretical Investigation ◽  
Diesel Engines ◽  
Equivalence Ratio ◽  
Combustion Efficiency ◽  
Oxygen Enrichment ◽  
Pollutant Emissions ◽  
Particulate Emissions ◽  
Engine Simulation ◽  
Hc Emissions ◽  
Experimental Findings

Increasing the in-cylinder oxygen availability of diesel engines is an effective method to improve combustion efficiency and to reduce particulate emissions. Past work on oxygen-enrichment of the intake air, revealed a large decrease of ignition delay, a remarkable decrease of soot emissions as well as reduction of CO and unburned hydrocarbon (HC) emissions while, brake specific fuel consumption (bsfc) remained unaffected or even improved. Moreover, experiments conducted in the past by authors revealed that oxygen-enrichment of the intake air (from 21% to 25% oxygen mole fraction) under high fuelling rates resulted to an increase of brake power output by 10%. However, a considerable increase of NOx emissions was recorded. This manuscript, presents the results of a theoretical investigation that examines the effect of oxygen enrichment of intake air, up to 30%v/v, on the local combustion characteristics, soot and NO concentrations under the following two in-cylinder mixing conditions: (1) lean in-cylinder average fuel/oxygen equivalence ratio (constant fuelling rate) and (2) constant in-cylinder average fuel/oxygen equivalence ratio (increased fuelling rate). A phenomenological engine simulation model is used to shed light into the influence of the oxygen content of combustion air on the distribution of combustion parameters, soot and nitric oxide inside the fuel jet, in all cases considered. Simulations were made for a naturally aspirated single-cylinder DI diesel engine “Lister LV1” at 2500 rpm and at various engine loads. The outcome of this theoretical investigation was contrasted with published experimental findings.

Aircraft Gas Turbine Emissions Challenge

1994 ◽  
Vol 116 (3) ◽  
pp. 474-477 ◽  
Author(s):  
B. L. Koff
Keyword(s):  
Fuel Efficiency ◽  
Harmful Effect ◽  
Pollutant Emissions ◽  
Nox Emissions ◽  
Oxides Of Nitrogen ◽  
Supersonic Aircraft ◽  
Significant Challenge ◽  
Unburned Hydrocarbon ◽  
Hc Emissions ◽  
New Generation

The new generation of jet powered aircraft faces a significant challenge to reduce pollutant emissions while increasing fuel efficiency. Carbon monoxide (CO) and unburned hydrocarbon (HC) emissions are already very low and continued control of these pollutants is expected as engine temperatures and pressure ratios are increased. In contrast, significant system design improvements are needed to reduce oxides of nitrogen (NOx) emissions because of their harmful effect on the earth’s ozone layer. This paper discusses the prospects and technical approaches for significant NOx reductions in current and future subsonic and supersonic aircraft.

scholarly journals Emissions and Stability Characteristics of Flameholders for Lean-Premixed Combustion

1992 ◽  
Author(s):  
Jeffrey A. Lovett ◽  
Nesim Abuaf
Keyword(s):  
Bluff Body ◽  
Flame Temperature ◽  
Perforated Plate ◽  
Premixed Combustion ◽  
Flame Stability ◽  
Nox Emissions ◽  
Lean Premixed Combustion ◽  
Lean Premixed ◽  
The Stability ◽  
Lean Conditions

An experimental study was conducted to determine the NOx emissions and flame stability associated with various flameholders used to support lean-premixed combustion of natural gas at gas turbine conditions. Data were obtained for velocities of 6 to 24 m/s, initial temperatures of 533 to 650 K, and pressures of 3.4 to 13.6 atm. Bluff-body, perforated-plate, and swirl-stabilized flameholders were tested and compared. The results confirm that NOx emissions at ultra-lean conditions scale with the flame temperature and are essentially independent of flameholder geometry for typical combustor residence times. The stability behavior, however, was strongly affected by flameholder type, illustrating the influence of fluid mechanics on flame stability. The flame stability was related also to the dynamics produced by combustion instability. A swirl-stabilized flameholder demonstrated the best stability characteristics at the expense of flameholder pressure drop.

scholarly journals Aircraft Gas Turbine Emissions Challenge

1993 ◽  
Author(s):  
B. L. Koff
Keyword(s):  
Fuel Efficiency ◽  
Harmful Effect ◽  
Pollutant Emissions ◽  
Nox Emissions ◽  
Oxides Of Nitrogen ◽  
Supersonic Aircraft ◽  
Significant Challenge ◽  
Unburned Hydrocarbon ◽  
Hc Emissions ◽  
New Generation

The new generation of jet powered aircraft faces a significant challenge to reduce pollutant emissions while increasing fuel efficiency. Carbon monoxide (CO) and unburned hydrocarbon (HC) emissions are already very low and continued control of these pollutants is expected as engine temperatures and pressure ratios are increased. In contrast, significant system design improvements are needed to reduce oxides of nitrogen (NOx) emissions because of their harmful effect on the earth’s ozone layer. This paper discusses the prospects and technical approaches for significant NOx reductions in current and future subsonic and supersonic aircraft.

Stability Limits of Premixed Methane-Air Microflames for Micropower Generation

2006 ◽  
Vol 326-328 ◽  
pp. 1133-1136
Author(s):  
Oh Chae Kwon ◽  
K.H. Lee ◽  
H.S. Ko ◽  
T. Kim
Keyword(s):  
Atmospheric Pressure ◽  
Equivalence Ratio ◽  
Heat Losses ◽  
Rich Region ◽  
Realistic Condition ◽  
Heat Recirculation ◽  
Micropower Generation ◽  
Tube Exit ◽  
The Stability ◽  
Stability Limits

Stability limits of premixed microflames were experimentally and computationally studied in order to understand the fundamental behavior of the flames when applied for micropower generation. Single microflames were generated on microtubes with inner diameters of 300-420 μm for methane-air mixtures at temperatures of 298-400 K and atmospheric pressure. For all the microflames at normal temperature, the stability limits were observed in a fuel-rich region, which is different from conventional macroflames exhibiting fuel-lean stability limits. Similar to the macroflames, however, the stability limits of the microflames show C-shaped curves in a tube exit Reynolds number (Re) – fuel equivalence ratio diagram, due to insufficient residence times and heat losses. For elevated temperature that is realistic condition for micropower generation using a heat-recirculation concept, the stability limits were extended toward the fuel-leaner conditions. Numerically predicted structure of microflames near the critical point (that is defined as the fuel-leanest condition among the C-shaped fuel-rich stability limits) showed significant fuel-dilution immediately near the tube exit due to a low Re effect, explaining why the stability limits of microflames are observed only in the fuel-rich region. Microcombustors for micropower generation should be designed to completely consume fuel for better performance.

scholarly journals Investigation of Waste Biogas Flame Stability Under Oxygen or Hydrogen-Enriched Conditions

Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4760
Author(s):  
Nerijus Striūgas ◽  
Rolandas Paulauskas ◽  
Raminta Skvorčinskienė ◽  
Aurimas Lisauskas
Keyword(s):  
Linear Correlation ◽  
Intensity Ratio ◽  
Spectral Intensity ◽  
Pollutant Emissions ◽  
Flame Stability ◽  
Nox Emissions ◽  
Production Rates ◽  
Flammability Limit ◽  
Flammability Limits ◽  
Stable Combustion

Increasing production rates of the biomethane lead to increased generation of waste biogases. These gases should be utilized on-site to avoid pollutant emissions to the atmosphere. This study presents a flexible swirl burner (~100 kW) with an adiabatic chamber capable of burning unstable composition waste biogases. The main combustion parameters and chemiluminescence emission spectrums were examined by burning waste biogases containing from 5 to 30 vol% of CH4 in CO2 under air, O2-enriched atmosphere, or with the addition of hydrogen. The tested burner ensured stable combustion of waste biogases with CH4 content not less than 20 vol%. The addition of up to 5 vol% of H2 expanded flammability limits, and stable combustion of the mixtures with CH4 content of 15 vol% was achieved. The burner flexibility to work under O2-enriched air conditions showed more promising results, and the flammability limit was expanded up to 5 vol% of CH4 in CO2. However, the combustion under O2-enriched conditions led to increased NOx emissions (up to 1100 ppm). Besides, based on chemiluminescence emission spectrums, a linear correlation between the spectral intensity ratio of OH* and CH* (IOH*/ICH*) and CH4 content in CO2 was presented, which predicts blow-off limits burning waste biogases under different H2 or O2 enrichments.

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