Effect of Nitrogen Dilution on the Lean Blowout Limit and Emissions of Premixed Propane/Air Swirl Flame

2014 ◽  
Vol 71 (2) ◽  
Author(s):  
Cheng Tung Chong ◽  
Chen Wei Kew ◽  
Ng Jo-Han ◽  
Boon Tuan Tee ◽  
Mohamad Nazri Mohd Jaafar
Keyword(s):  
Digital Camera ◽  
Atmospheric Condition ◽  
Nitrogen Addition ◽  
Lean Blowout ◽  
Nitrogen Dilution ◽  
Flame Burner ◽  
Unburned Hydrocarbons ◽  
Flame Shape ◽  
Flame Imaging ◽  
Swirl Flame

The effects of nitrogen dilution on propane/air flame and emissions was investigated using a model gas turbine type swirl flame burner. The burner consists of a six-vane axial swirler and a combustor wall made from quartz tube. Nitrogen was diluted at 5%, 10% and 15% by volume of the total main air flow rate with propane/air mixture at the burner plenum prior to combustion at atmospheric condition. Direct flame imaging was performed using a digital camera to observe the flame shape, intensity and lean blowout phenomenon of premixed nitrogen-diluted propane/air flames. The result shows that nitrogen addition to propane/air flame reduces flame intensity and lean blowout limit, making the nitrogen-diluted flames more susceptible to blowout. Emissions results show that NOx reduce with the increase of nitrogen dilution rate, while the effect on carbon monoxides and unburned hydrocarbons are insignificant.

Flame and Emission Characteristics of a Premixed Swirl-stabilised Burner

2014 ◽  
Vol 71 (2) ◽  
Author(s):  
Chen Wei Kew ◽  
Cheng Tung Chong ◽  
Ng Jo-Han ◽  
Boon Tuan Tee ◽  
Mohamad Nazri Mohd Jaafar
Keyword(s):  
Equivalence Ratio ◽  
Soot Formation ◽  
Atmospheric Condition ◽  
Emission Characteristics ◽  
Flow Rates ◽  
Lean Blowout ◽  
Unburned Hydrocarbons ◽  
Flame Shape ◽  
Flame Imaging ◽  
Swirl Flame

The flame and emission characteristics of a premixed gaseous flame swirl burner are investigated under various equivalence ratio. The swirl flame is established using propane/air mixture at atmospheric condition. Flame imaging was performed to compare the global flame shape and intensity over a range of equivalence ratios and flow rates. Fuel-rich flame shows increased intensity due to the presence of soot formation. The lean blowout test was performed to determine the operating limit of the burner. Emissions of the propane swirl flame were measured at the exit of the burner outlet. Results show that NOx emissions peak at stoichiometric condition, f =1 as compared to the lean- and rich-burning regions. Carbon monoxide (CO) and unburned hydrocarbons (UHC) emissions were found to be low (< 10 ppm) under premixed, continuous swirl burning conditions for the equivalence ratio range of f = 0.7-1.1.

Characteristics of Several Steam and Nitrogen Diluted Methods on Hydrogen-Riched Medium Heating Value Syngas Fuel Diffusion Flame

2008 ◽  
Author(s):  
Gang Xu ◽  
Aibin Fang ◽  
Quan Liu ◽  
Bin Yu ◽  
Chaoqun Nie ◽  
...  
Keyword(s):  
Safety Margin ◽  
Nitrogen Addition ◽  
Steel Sample ◽  
Inert Gases ◽  
Nox Emissions ◽  
Stainless Steel Sample ◽  
Lean Blowout ◽  
O2 Concentration ◽  
Nitrogen Dilution ◽  
Fuel Dilution

For the diffusion syngas flames, inert gases dilution is one of the effective techniques to reduce NOx emissions. In this paper, five methods of steam or nitrogen dilution have been investigated on an atmospheric-pressure downscaled test rig: Air dilution with steam; Fuel dilution with steam; Fuel dilution with N2; Direct dilution with steam; Direct dilution with N2. The experimental results indicate that each method could suppress the NOx emissions less than 10 ppm@15%O2 with proper steam or nitrogen addition while CO emission below 50 ppm@15%O2. However, the optimum steam or nitrogen consumption rate of each method is very different from other methods. For example, the air dilution with steam method needs more steam consumption than fuel dilution with stream and direct dilution with steam. The temperature distribution and species (i.e. CO, NOx, CO2 and O2) concentration distribution of the model combustor have been investigated by a high response thermocouple (type B) and a water-cooled stainless steel sample probe, respectively. The lean blowout (LBO) limits of five methods are obtained at fixed air flowrate condition. The LBO safety margin of direct dilution methods shows much broader than that of those fuel dilution methods. Furthermore, fuel dilution reaches the LBO limit at constant DOD (the flowrate ratio of dilution to syngas) for different equivalence ratio.

scholarly journals Wavelet analysis of flame blowout of a liquid-fueled swirl burner with quarls

2019 ◽  
Vol 67 (5) ◽  
pp. 394-403
Author(s):  
Viktor Józsa ◽  
Gergely Novotni
Keyword(s):  
Wavelet Transformation ◽  
Acoustic Noise ◽  
Operating Regime ◽  
Pollutant Emissions ◽  
Swirl Number ◽  
Axial Thrust ◽  
Lean Blowout ◽  
Swirl Combustion ◽  
Thrust Control ◽  
Flame Shape

Lean swirl combustion is the leading burner concept today, used in several steadyoperating applications to ensure awide operating range and low pollutant emissions. Approaching lean blowout is highly desired by design to achieve the lowest possible NOX emission. It was shown earlier that quarls could significantly extend the operating regime of liquid-fueled swirl burners. In the present study, the accompanying acoustic noise is evaluated by continuous wavelet transformation to show the effect of various quarl geometries on lean flame blowout. However, the desired flame shape of swirl burners is V, first, and a straight flame, and then a transitory regime can be observed before the developed V-shaped flame through increasing the swirl number. If the axial thrust is excessive, blowout might occur in earlier stages. Presently, the characteristic bands before blowout were analyzed and evaluated at various quarl geometries, swirl numbers, and atomizing pressures. The latter parameter also acts as an axial thrust control to adjust the swirl number. firstly, a straight flame, then a transitory regime can be observed before the developed V-shaped flame through increasing the swirl number. If the axial thrust is excessive, blowout might occur in earlier stages. Presently, the characteristic bands before blowout were analyzed and evaluated at various quarl geometries, swirl numbers, and atomizing pressures. The latter parameter also acts as an axial thrust control to adjust the swirl number.

Nitrogen Diluted Jet Flames in the Presence of Coflowing Air

2011 ◽  
Author(s):  
James D. Kribs ◽  
Tamir S. Hasan ◽  
Kevin M. Lyons
Keyword(s):  
Diffusion Flame ◽  
Axial Position ◽  
Flammability Limit ◽  
Jet Flames ◽  
Flow Rates ◽  
Nitrogen Dilution ◽  
Flame Shape ◽  
Methane Flow

The purpose of this study is to observe methane jet flames under varying levels of nitrogen dilution and coflowing air. The jet flames were examined in order to determine the conditions for which liftoff and blowout occur under conditions that strain the flame. Methane flow rates were varied, corresponding to intermediate lifted positions to blowout. A sequence of images were taken at each level of dilution and coflow, and were used to determine the lowest radial and axial position of the flammability limit. These flammability regions were compared to the lean flammability limit. It was observed that flame shape and liftoff were considerably more influenced by the effects of the coflowing air compared to the presence of the diluents, and that flames under coflow lost the trailing diffusion flame earlier, which has been shown to be a marker for flame blowout.

Detection of Precursor Event Before Blowout in a Gas Turbine Type Combustor at Atmospheric Pressure

2012 ◽  
Author(s):  
K. P. Aditya ◽  
T. M. Muruganandam
Keyword(s):  
Gas Turbine ◽  
High Speed ◽  
Gas Turbine Combustor ◽  
High Speed Imaging ◽  
Safety Hazard ◽  
Lean Blowout ◽  
Imaging Camera ◽  
Swirl Flame ◽  
Vane Angle ◽  
Lean Conditions

The need for stringent emission requirements compel modern gas turbine (GT) combustors to work under lean conditions and lower temperatures, thereby reducing NOx emissions. The operation of a combustor close to lean blowout limit increases the risk of a complete flame blowout posing a safety hazard in aircraft engines. A study was carried out on a divergent gas turbine combustor, in order to sense and detect a similar blowout phenomenon in a non/partially premixed swirl flame. Inside combustor, 45° vane angle swirler created weak recirculation zone. New swirler with 5° and 60° at entry and exit respectively was used as replacement. 5 bar and 6 bar of stagnation pressure of air were used as loading parameters during the experimentation. Photodiode sensors and high speed imaging camera were used to record data of flame. It was observed that, bursts (or unsteady events) characterized by an almost complete loss of flame i. e. abrupt extinctions were followed by re-occurrence of flame. ‘Precursor events’ before flame blowout were detected. These events occurred and reoccurred in an interval of several milliseconds. In both scenarios, high speed visualization was recorded at 1000 Hz for 16–20 seconds. Detection of precursor events for the liquid fuelled combustor will assist in carrying out further research using sensing methods to estimate the proximity of the combustor to LBO.

scholarly journals Effect of Gravity on Radiative Heat Feedback on Small-Scale Pool Fires Using the Radiative Absorption Model

2016 ◽  
Vol 10 (10) ◽  
pp. 150
Author(s):  
Koei Yoshida ◽  
Ryo Takahashi ◽  
Hiroyuki Torikai ◽  
Akihiko Ito
Keyword(s):  
Radiative Heat ◽  
Digital Camera ◽  
Time Variability ◽  
Small Scale ◽  
Absorption Model ◽  
Pool Fires ◽  
Gravity Condition ◽  
Partial Gravity ◽  
Flame Shape ◽  
Radiative Absorption

The flame characteristics of pool fires such as their height vary depending on gravity. To improve our understanding of the effects of gravity on flame characteristics, we experimentally investigated small-scale pool fires under conditions of normal to partial gravity; using the drop tower at Hirosaki University in Japan to obtain arbitrary partial gravity condition, which varied from 1 G to 0.55 G. We performed the measurement of the temperature distribution with a thermocouple and that of the flame shape with a digital camera. Based on these data, we estimated radiative heat feedback using our new model “The radiative absorption model”. It becomes easy to estimate radiative heat transfer using this model if flames have complicated shapes and time variability. From these analyses, we made clear that the radiative heat feedback of small-scale pool fires decreases under partial gravity environment.

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