Low-NOx Combustion of Fuel Spray-Air Mixtures From a Converging Splitter in a Co-Swirling Annular Air Flow

2017 ◽  
Author(s):  
Shunsaku Oide ◽  
Masanao Iwakura ◽  
Mai Takaoka ◽  
Shunsuke Kasuga ◽  
Shigeru Hayashi
Keyword(s):  
Combustion Chamber ◽  
Flame Structure ◽  
Chemical Species ◽  
Mie Scattering ◽  
Nox Emissions ◽  
Burner Exit ◽  
Air Jet ◽  
Air Temperatures ◽  
Flame Imaging ◽  
Vane Angle

A unique burner consisting of a pressure swirl atomizer, a converging outer shroud, a coaxially assembled converging splitter, and coaxial swirlers at the inlets of the inner and outer circuits is being developed for low-NOx emissions (below 0.5 g/kg-fuel) at the higher inlet air temperatures and better flame stability at the lower inlet air temperatures. Liquid fuel is atomized only into the air flowing in the inner circuit and the resulting mixture jet is injected into the combustion chamber from the exit of the splitter, surrounded by the annular swirling air jet from the outer circuit. Emissions measurements, direct flame imaging, and Mie scattering imaging of the sprays were conducted for inner swirler vane angles of 40 and 50 degrees and a fixed outer swirler vane angle of 45 degrees at inlet air temperatures of 453 to 753 K (a 100-degree step) and atmospheric pressure. A lifted flame was stabilized with the flame front at a distance from the burner exit. Direct flame images were successfully used to correlate the NOx emissions with flame structure. Additionally, local gas sampling was done at 753 K. The measured distributions of equivalence ratio and of chemical species concentrations in the combustion chamber were used to explain the lower NOx emissions for the smaller vane angle.

scholarly journals Modeling the regional impact of ship emissions on NO<sub>x</sub> and ozone levels over the Eastern Atlantic and Western Europe using ship plume parameterization

2010 ◽  
Vol 10 (14) ◽  
pp. 6645-6660 ◽  
Author(s):  
P. Huszar ◽  
D. Cariolle ◽  
R. Paoli ◽  
T. Halenka ◽  
M. Belda ◽  
...  
Keyword(s):  
Large Scale ◽  
Western Europe ◽  
Surface Ozone ◽  
Chemical Species ◽  
Nitrogen Monoxide ◽  
Ozone Production ◽  
Nox Emissions ◽  
Ship Emissions ◽  
Concentrated Source ◽  
The Impact

Abstract. In general, regional and global chemistry transport models apply instantaneous mixing of emissions into the model's finest resolved scale. In case of a concentrated source, this could result in erroneous calculation of the evolution of both primary and secondary chemical species. Several studies discussed this issue in connection with emissions from ships and aircraft. In this study, we present an approach to deal with the non-linear effects during dispersion of NOx emissions from ships. It represents an adaptation of the original approach developed for aircraft NOx emissions, which uses an exhaust tracer to trace the amount of the emitted species in the plume and applies an effective reaction rate for the ozone production/destruction during the plume's dilution into the background air. In accordance with previous studies examining the impact of international shipping on the composition of the troposphere, we found that the contribution of ship induced surface NOx to the total reaches 90% over remote ocean and makes 10–30% near coastal regions. Due to ship emissions, surface ozone increases by up to 4–6 ppbv making 10% contribution to the surface ozone budget. When applying the ship plume parameterization, we show that the large scale NOx decreases and the ship NOx contribution is reduced by up to 20–25%. A similar decrease was found in the case of O3. The plume parameterization suppressed the ship induced ozone production by 15–30% over large areas of the studied region. To evaluate the presented parameterization, nitrogen monoxide measurements over the English Channel were compared with modeled values and it was found that after activating the parameterization the model accuracy increases.

scholarly journals Reduced NOx Emissions Using Low Radial Swirler Vane Angles

1991 ◽  
Author(s):  
H. S. Alkabie ◽  
G. E. Andrews
Keyword(s):  
Gas Turbines ◽  
Fuel Injection ◽  
Combustion Efficiency ◽  
Inlet Temperature ◽  
Nox Emissions ◽  
Primary Zone ◽  
Industrial Gas Turbines ◽  
Curved Blade ◽  
Swirl Vane ◽  
Vane Angle

The influence of vane angle and hence swirl number of a radial swirler on the weak extinction, combustion inefficiency and NOx emissions was investigated at lean gas turbine combustor primary zone conditions. A 140mm diameter atmospheric pressure low NOx combustor primary zone was developed with a Mach number simulation of 30% and 43% of the combustor air flow into the primary zone through a curved blade radial swirler. The range of radial swirler vane angles was 0–60 degrees and central radially outward fuel injection was used throughout with a 600K inlet temperature. For zero vane angle radially inward jets were formed that impinged and generated a strong outer recirculation. This was found to have much lower NOx characteristics compared with a 45 degree swirler at the same pressure loss. However, the lean stability and combustion efficiency in the near weak extinction region was not as good. With swirl the central recirculation zone enhanced the combustion efficiency. For all the swirl vane angles there was little difference in combustion inefficiency between the swirlers. However, the NOx emissions were reduced at the lowest swirl angles and vane angles in the range 20–30 degrees were considered to be the optimum for central injection. NOx emissions for central injection as low as 5ppm at 15% oxygen and 1 bar were demonstrated for zero swirl and 20 degree swirler vane angle. This would scale to well under 25 ppm at pressure for all current industrial gas turbines.

CO and OH Imaging in Flames Using a Single Broadband Femtosecond Laser Pulse

2020 ◽  
Author(s):  
Pradeep Parajuli ◽  
Ayush Jain ◽  
Waruna D. Kulatilaka
Keyword(s):  
Laser Pulse ◽  
Reaction Zone ◽  
Turbulent Flame ◽  
Flame Structure ◽  
Chemical Species ◽  
Oxidation Reactions ◽  
Simultaneous Excitation ◽  
Spatiotemporal Information ◽  
Flame Burner ◽  
Fs Laser

Abstract Carbon monoxide (CO) and hydroxyl (OH) are the two key intermediate species formed during chemical reactions inside gas turbine combustors. Spatiotemporal information and a detailed understanding of CO formation in the reaction zone are important during the combustion processes as a major part of the heat release is obtained from the oxidation of CO to CO2. Turbulent flame structures and reaction zone in different flame conditions can also be visualized through the spatial distribution profiles of OH. In the current study, both these species are excited simultaneously using a single ultrashort, broad spectral bandwidth of approximately 100-femtosecond (fs) duration laser pulse at λ = 283.8 nm. Subsequent fluorescence signals are separated through spectral filters of appropriate bandwidth and imaged using two cameras. This present study was performed in a McKenna flat-flame burner with ethylene/air as a pilot flame and non-premixed turbulent ethylene jet at the center. The partial spectral overlap of CO–X (4,0) and OH A–X (1,0) transitions are utilized for simultaneous excitation, thereby characterize the overall flame structure (via OH) and regions of oxidation reactions (via CO) in a range of flame conditions. Besides, CO and OH profiles follow the trends obtained from model predictions for a range of equivalence ratios in ethylene/air flames stabilized over the Hencken calibration burner. These results are used for obtaining quantitative calibrations of CO and OH signals. Overall, the present study extends the applicability of a single, broadband fs laser pulse for simultaneous imaging of multiple chemical species in flame.

scholarly journals Development and application of observable response indicators for design of an effective ozone and fine particle pollution control strategy in China

2019 ◽  
Author(s):  
Jia Xing ◽  
Dian Ding ◽  
Shuxiao Wang ◽  
Zhaoxin Dong ◽  
James T. Kelly ◽  
...  
Keyword(s):  
Control Strategy ◽  
Pollution Control ◽  
Eastern China ◽  
National Level ◽  
Chemical Species ◽  
River Delta ◽  
Effective Control ◽  
Nox Emissions ◽  
Pm2.5 Exposure ◽  
Response Indicators

Abstract. Designing effective control policies requires efficient quantification of the nonlinear response of air pollution to emissions. However, neither the current observable indicators nor the current indicators based on response-surface modeling (RSM) can fulfill this requirement. Therefore, this study developed new observable RSM-based indicators and applied them to ambient fine particulate matter (PM2.5) and ozone (O3) pollution control in China. The performance of these observable indicators in predicting O3 and PM2.5 chemistry was compared with that of the current RSM-based indicators. H2O2 × HCHO/NO3 and total ammonia ratio, which exhibited the best performance among indicators, were proposed as new observable O3- and PM2.5-chemistry indicators, respectively. Strong correlations between RSM-based and traditional observable indicators suggested that a combination of ambient concentrations of certain chemical species can serve as an indicator to approximately quantify the response of O3 and PM2.5 to changes in precursor emissions. The observable RSM-based indicator for O3 (observable peak ratio) effectively captured the strong NOx-saturated regime in January and the NOx-limited regime in July, as well as the strong NOx-saturated regime in northern and eastern China and their key regions, including the Yangtze River Delta and Pearl River Delta. The observable RSM-based indicator for PM2.5 (observable flex ratio) also captured strong NH3-poor condition in January and NH3-rich condition in April and July, as well as NH3-rich in northern and eastern China and the Sichuan Basin. Moreover, analysis of these newly developed observable response indicators suggested that the simultaneous control of NH3 and NOx emissions produces greater benefits in provinces with higher PM2.5 exposure by up to 12 µg m−3 PM2.5 per 10 % NH3 reduction compared with NOx control only. Control of volatile organic compound (VOC) emissions by as much as 40 % of NOx controls is necessary to obtain the co-benefits of reducing both O3 and PM2.5 exposure at the national level when controlling NOx emissions. However, the VOC-to-NOx ratio required to maintain benefits varies significantly from 0 to 1.2 in different provinces, suggesting that a more localized control strategy should be designed for each province.

A Comparison of the Influence of Fuel/Air Unmixedness on NOx Emissions in Lean Premixed, Non-Catalytic and Catalytically Stabilized Combustion

1997 ◽  
Author(s):  
A. Schlegel ◽  
M. Streichsbier ◽  
R. Mongia ◽  
R. Dibble
Keyword(s):  
Combustion Chamber ◽  
Catalytic Combustion ◽  
Combustion Process ◽  
Tubular Reactor ◽  
Optical Probe ◽  
Nox Emissions ◽  
Fuel Concentration ◽  
Lean Premixed ◽  
Inlet Conditions ◽  
Over Time

Experimental results on the influence of temporal unmixedness on NOx emissions are presented for both non-catalytic and catalytically stabilized, lean premixed combustion. The test rig used for the experiments consists of a fuel/air mixing section which allows variation of the degree of temporal unmixedness while maintaining a uniform “average over time” concentration profile over the cross section at the inlet to the combustion chamber. The unmixedness is measured as “rms fluctuations in fuel concentration” by an optical probe using laser absorption at 3.39μm over a 9mm gap. “Average over time” measurements are taken with “conventional” suction probe analyzers. The combustion chamber is an insulated, tubular reactor (i.d. 26.4mm). At the inlet to the combustion chamber a honeycomb monolith section is inserted. This monolith is either catalytically active or inactive for catalytically stabilized or non-catalytic combustion respectively. For both modes, the exact same inlet conditions are applied. In catalytically stabilized combustion a fraction of the fuel is consumed within the catalyst and the remaining fuel is burnt in the subsequent homogeneous combustion zone. It is shown that catalytically stabilized combustion yields lower NOx emissions and, more important, that the effect of temporal fuel/air unmixedness on NOx emissions is much smaller than with non-catalytic combustion under identical inlet conditions. Experimental evidence leads to the conclusion, that the catalyst is capable of reducing temporal fluctuations in fuel concentration and/or temperature in the combustion process, thereby preventing excess NOx formation. As a result, the requirements on mixing quality are less stringent when using catalytically stabilized combustion instead of conventional, non-catalytic combustion.

Effects of Pilot Fuel and Liner Cooling on the Flame Structure in a Full Scale Swirl-Stabilized Combustion Setup

2009 ◽  
Author(s):  
Jens Fa¨rber ◽  
Rainer Koch ◽  
Hans-Jo¨rg Bauer ◽  
Matthias Hase ◽  
Werner Krebs
Keyword(s):  
Combustion Chamber ◽  
Fuel Injection ◽  
Flame Structure ◽  
Cone Angle ◽  
Flow Patterns ◽  
Flame Stabilization ◽  
Operating Conditions ◽  
Combustion Noise ◽  
Pilot Fuel ◽  
Combustor Liner

The flame structure and the limits of operation of a lean premixed swirl flame were experimentally investigated under piloted and non-piloted conditions. Flame stabilization and blow out limits are discussed with respect to pilot fuel injection and combustor liner cooling for lean operating conditions. Two distinctly different flow patterns are found to develop depending on piloting and liner cooling parameters. These flow patterns are characterized with respect to flame stability, blow out limits, combustion noise and emissions. The combustion system explored consists of a single burner similar to the burners used in Siemens annular combustion systems. The burner feeds a distinctively non-adiabatic combustion chamber operated with natural gas under atmospheric pressure. Liner cooling is mimicked by purely convective cooling and an additional flow of ‘leakage air’ injected into the combustion chamber. Both, this additional air flow and the pilot fuel ratio were found to have a strong influence on the flow structure and stability of the flame close to the lean blow off limit (LBO). It is shown by Laser Doppler Velocimetry (LDV) that the angle of the swirl cone is strongly affected by pilot fuel injection. Two distinct types of flow patterns are observed close to LBO in this large scale setup: While non-piloted flames exhibit tight cone angles and small inner recirculation zones (IRZ), sufficient piloting results in a wide cone angle and a large IRZ. Only in the latter case, the main flow becomes attached to the combustor liner. Flame structures deduced from flow fields and CH-Chemiluminescence images depend on both the pilot fuel injection and liner cooling.

NOx Emissions Reduction in an Innovative Industrial Gas Turbine Combustor (GE10 Machine): A Numerical Study of the Benefits of a New Pilot-System on Flame Structure and Emissions

2005 ◽  
Author(s):  
Antonio Andreini ◽  
Bruno Facchini ◽  
Luca Mangani ◽  
Antonio Asti ◽  
Gianni Ceccherini ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Numerical Study ◽  
Flame Structure ◽  
Combustion Model ◽  
Emissions Reduction ◽  
Minimal Amount ◽  
Nox Emissions ◽  
Ambient Temperatures ◽  
Wide Range

One of the driving requirements in gas turbine design is emissions reduction. In the mature markets (especially the North America), permits to install new gas turbines are granted provided emissions meet more and more restrictive requirements, in a wide range of ambient temperatures and loads. To meet such requirements, design techniques have to take advantage also of the most recent CFD tools. As a successful example of this, this paper reports the results of a reactive 3D numerical study of a single-can combustor for the GE10 machine, recently updated by GE-Energy. This work aims to evaluate the benefits on the flame shape and on NOx emissions of a new pilot-system located on the upper part of the liner. The former GE10 combustor is equipped with fuel-injecting-holes realizing purely diffusive pilot-flames. To reduce NOx emissions from the current 25 ppmvd@15%O2 to less than 15 ppmvd@15%O2 (in the ambient temperature range from −28.9°C to +37.8°C and in the load range from 50% and 100%), the new version of the combustor is equipped with 4 swirler-burners realizing lean-premixed pilot flames; these flames in turn are stabilized by a minimal amount of lean-diffusive sub-pilot-fuel. The overall goal of this new configuration is the reduction of the fraction of fuel burnt in diffusive flames, lowering peak temperatures and therefore NOx emissions. To analyse the new flame structure and to check the emissions reduction, a reactive RANS study was performed using STAR-CD™ package. A user-defined combustion model was used, while to estimate NOx emissions a specific scheme was also developed. Three different ambient temperatures (ISO, −28.9°C and 37.8°C) were simulated. Results were then compared with experimental measurements (taken both from the engine and from the rig), resulting in reasonable agreement. Finally, an additional simulation with an advanced combustion model, based on the laminar flamelet approach, was performed. The model is based on the G-Equation scheme but was modified to study partially premixed flames. A geometric procedure to solve G-Equation was implemented as add-on in STAR-CD™.

Investigation of Hydrogen Enriched Natural Gas Flames in a SGT-700/800 Burner Using OH PLIF and Chemiluminescence Imaging

2014 ◽  
Vol 137 (3) ◽  
Author(s):  
Andreas Lantz ◽  
Robert Collin ◽  
Marcus Aldén ◽  
Annika Lindholm ◽  
Jenny Larfeldt ◽  
...  
Keyword(s):  
Natural Gas ◽  
Combustion Chamber ◽  
Flame Front ◽  
Gas Turbines ◽  
Dynamic Pressure ◽  
Pressure Fluctuations ◽  
Burner Exit ◽  
Planar Laser ◽  
Industrial Gas Turbines ◽  
Dynamic Pressure Measurements

The effect of hydrogen enrichment to natural gas flames was experimentally investigated at atmospheric pressure conditions using flame chemiluminescence imaging, planar laser-induced fluorescence of hydroxyl radicals (OH PLIF), and dynamic pressure monitoring. The experiments were performed using a third generation dry low emission (DLE) burner used in both SGT-700 and SGT-800 industrial gas turbines from Siemens. The burner was mounted in an atmospheric combustion test rig at Siemens with optical access in the flame region. Four different hydrogen enriched natural gas flames were investigated; 0 vol. %, 30 vol. %, 60 vol. %, and 80 vol. % of hydrogen. The results from flame chemiluminescence imaging and OH PLIF show that the size and shape of the flame was clearly affected by hydrogen addition. The flame becomes shorter and narrower when the amount of hydrogen is increased. For the 60 vol. % and 80 vol. % hydrogen flames the flame has moved upstream and the central recirculation zone that anchors the flame has moved upstream the burner exit. Furthermore, the position of the flame front fluctuated more for the full premixed flame with only natural gas as fuel than for the hydrogen enriched flames. Measurements of pressure drop over the burner show an increase with increased hydrogen in the natural gas despite same air flow thus confirming the observation that the flame front moves upstream toward the burner exit and thereby increasing the blockage of the exit. Dynamic pressure measurements in the combustion chamber wall confirms that small amounts of hydrogen in natural gas changes the amplitude of the dynamic pressure fluctuations and initially dampens the axial mode but at higher levels of hydrogen an enhancement of a transversal mode in the combustion chamber at higher frequencies could occur.

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