scholarly journals Fundamental Study on Ammonia Low-NOx Combustion Using Two-Stage Combustion by Parallel Air Jets

Processes ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 23
Author(s):  
Kenta Kikuchi ◽  
Ryuichi Murai ◽  
Tsukasa Hori ◽  
Fumiteru Akamatsu
Keyword(s):  
Nox Reduction ◽  
Axial Direction ◽  
Two Stage ◽  
Fundamental Study ◽  
Lean Combustion ◽  
Air Jets ◽  
Stage Combustion ◽  
Low Nox Combustion ◽  
Secondary Air ◽  
Air Nozzle

Ammonia, which has advantages over hydrogen in terms of storage and transportation, is increasingly expected to become a carbon-free fuel. However, the reduction of fuel NOx emitted from ammonia combustion is an unavoidable challenge. There is the report that two-stage combustion with parallel independent jets could achieve Low-NOx combustion under ammonia/methane co-firing conditions. In order to further improve NOx reduction, we experimentally evaluated the effects of secondary air nozzle parameters, such as nozzle diameter and nozzle locations, on combustion characteristics in two-stage combustion of ammonia/natural gas co-firing using parallel independent jets. As a result of the experiments under various secondary air nozzle conditions, it was found that under the conditions where NOx was significantly reduced, the peak temperature in the furnace was observed at 300–500 mm in the axial direction from the burner, and then the temperature decreased toward the downstream of the furnace. We assumed that this temperature distribution reflected the mixing conditions of the fuel and secondary air and estimated the combustion conditions in the furnace. It was confirmed that the two-stage combustion was effective in reducing NOx by forming a fuel rich region near the downstream of the burner, and the lean combustion of the unburned portion of the first stage combustion with secondary air. We confirmed that the low NOx effects could be achieved by two-stage combustion using independent jets from the same wall under appropriate combustion and air nozzle conditions.

scholarly journals Experimental Investigation of an Atmospheric Rectangular Rich Quench Lean Combustor Sector for Aeroengines

1997 ◽  
Author(s):  
Peter Griebel ◽  
Michael Fischer ◽  
Christoph Hassa ◽  
Eggert Magens ◽  
Henning Nannen ◽  
...  
Keyword(s):  
Research Work ◽  
Nox Formation ◽  
Lean Combustion ◽  
Air Jets ◽  
Primary Zone ◽  
Low Emission ◽  
Measuring Techniques ◽  
Annular Combustor ◽  
High Turbulence ◽  
Secondary Air

In this research work the potential of rich quench lean combustion for low emission aeroengines is investigated in a rectangular atmospheric sector, representing a segment of an annular combustor. For a constant design point (cruise) the mixing process and the NOx formation are studied in detail by concentration, temperature and velocity measurements using intrusive and non-intrusive measuring techniques. Measurements at the exit of the homogeneous primary zone show relatively high levels of non-thermal NO. The NOx formation in the quench zone is very low due to the quick mixing of the secondary air achieved by an adequate penetration of the secondary air jets and a high turbulence level. The NOx and CO emissions at the combustor exit are low and the pattern factor of the temperature distribution is sufficient.

scholarly journals The Effect of Rich-Lean Rapid Two-Stage Combustion for NOx Reduction in a Diesel Engine.

2000 ◽  
Vol 66 (648) ◽  
pp. 2209-2214
Author(s):  
Mitsuru KONNO ◽  
Suichi Kajitani ◽  
Toshiyuki IWASE ◽  
Yasuyuki WATANABE
Keyword(s):  
Diesel Engine ◽  
Nox Reduction ◽  
Two Stage ◽  
Stage Combustion

Experimental and Numerical Investigation of a Planar Combustor Sector at Realistic Operating Conditions

2000 ◽  
Vol 123 (4) ◽  
pp. 810-816 ◽  
Author(s):  
M. Carl ◽  
T. Behrendt ◽  
C. Fleing ◽  
M. Frodermann ◽  
J. Heinze ◽  
...  
Keyword(s):  
Reduction Potential ◽  
Measurement Techniques ◽  
Nox Reduction ◽  
Mie Scattering ◽  
Isothermal Flow ◽  
Operating Conditions ◽  
Aerospace Research ◽  
Air Jets ◽  
Secondary Air ◽  
German Aerospace

Results of an ongoing collaboration between the engine manufacturer MTU and the German aerospace research center DLR on the NOx reduction potential of conventional combustors are reported. A program comprising optical sector combustor measurements at 1, 6, and 15 bars and CFD calculations is carried out. The aims are to gather information in the combustor at realistic operating conditions, to understand the differences between the sector flow field and data from tubular combustors, to verify the used CFD, and to discover the benefits and limitations of the applied optical diagnostics. Selected results of measurements and calculations of the isothermal flow and of measurements at 6 bars and 700 K at a rich-lean and overall lean AFR are reported. The used measurement techniques were LDA, PDA, Mie scattering on kerosene, quantitative light scattering, OH* chemiluminescence, and LIF on OH. The measurements were able to confirm the intended quick and homogeneous mixing of the three staggered rows of secondary air jets.

The Mechanics of Flame and Air Jets

1937 ◽  
Vol 137 (1) ◽  
pp. 11-72 ◽  
Author(s):  
R. F. Davis
Keyword(s):  
Axial Direction ◽  
Flame Length ◽  
Similar Process ◽  
Mean Velocity ◽  
Ignition Point ◽  
Jet Mixing ◽  
Air Jets ◽  
Air Jet ◽  
The Mean ◽  
Secondary Air

Consideration of the conditions existing within the turbulent zone formed by a free disperse jet mixing with fluid at rest surrounding it, leads to the conception of an equation for the mean velocity of the jet in an axial direction. Combining the latter equation with that for the upward drift velocity of the gases in a furnace, an expression is obtained for the trajectory of an overfire, or secondary air jet, projected into the furnace. By a similar process the method is extended to the case of a flame jet, taking into account its acceleration due to buoyancy. The mechanism of combustion is next considered, commencing with an examination of the factors controlling the position of the ignition point in a flame jet, and the derivation of an expression for its location in a powdered-fuel flame. This is followed by the development of a formula for the burning rate of powdered fuel suspended in air, which when combined with that for the mean velocity in a flame jet, enables a relationship to be established between the flame length and the particle size, for the ideal case of a uniform powder. Subsequently, the grading or non-uniform nature of actual powders is taken into account. A method is also described for plotting a flame characteristic, showing the effect of fineness of grinding, turbulence, and burner design on the losses due to unburnt combustible.

scholarly journals NOx reduction by 13A/hydrogen mixed combustion using two-stage combustion

2020 ◽  
Vol 2020.95 (0) ◽  
pp. P_022
Author(s):  
Kohei YASUHIRO ◽  
Ryosuke MATSUMOTO ◽  
Seigo JUURI ◽  
Takumi YAMAMOTO ◽  
Takuma NAKAMURA ◽  
...  
Keyword(s):  
Nox Reduction ◽  
Two Stage ◽  
Stage Combustion

Lean/Lean Staged Low NOx Combustion for Near Stoichiometric Gas Turbine Primary Zone Conditions

2001 ◽  
Author(s):  
M. C. Mkpadi ◽  
G. E. Andrews ◽  
I. Khan ◽  
M. N. Mohd Jaafar ◽  
M. Pourkashanian ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Atmospheric Pressure ◽  
Equivalence Ratio ◽  
Fuel Injection ◽  
Nox Emissions ◽  
Two Stage ◽  
Second Stage ◽  
Lean Combustion ◽  
Primary Zone ◽  
Low Nox Combustion

A two-stage lean/lean primary zone at simulated atmospheric pressure gas turbine combustion conditions was shown to give low NOx emissions at atmospheric pressure and 600K inlet temperature. All the combustion air was admitted to the first lean stage, where very lean <5ppm low NOx combustion occurred. A 40mm outlet diameter radial swirler with radial vane passage fuel injection was used in the first stage. After completion of this first stage lean combustion, second stage of fuel injection with no associated air occurred 320mm downstream of the primary swirler outlet, using 76mm radially inward wall injection. This was followed by a dump flow expansion to a 140mm diameter combustor. This provided an expansion shear layer and associated turbulence to mix the second stage fuel with the outlet products from the primary swirl combustion. The second stage fuel burned in the depleted oxygen (∼12%) from the first stage, but still remained a lean combustion zone overall. This design was intended to achieve engine power variation using the second stage fuel. The use of the second stage fuel was shown to reduce the NOx emissions by 50% compared with injecting all of the fuel into the first stage radial swirler. Emission levels of NOx at a first stage swirler equivalence ratio of 0.4 were below 5ppm and at an overall primary zone equivalence ratio of 0.8 with the two stage fuel injection, NOx emissions were about 20ppm. The second stage flame radial distribution of equivalence ratio and emissions was determined by gas analysis. The second stage NOx formation was predicted using CFD with flamelet modelling, with a flamelet strain library computed for 12% oxygen combustion. The mole fraction profile of NOx and combustion temperatures for a range of strain rates in the second stage were predicted. NOx emissions at 0.65 equivalence ratio overall was predicted to be 23ppm at 15% oxygen compared with 16ppm measured. Improved second stage fuel mixing is required to achieve lower NOx emissions and the use of wall turbulators is recommended.

scholarly journals Combustion Characteristics and NOx Emission through a Swirling Burner with Adjustable Flaring Angle

Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 2173 ◽  
Author(s):  
Yafei Zhang ◽  
Rui Luo ◽  
Yihua Dou ◽  
Qulan Zhou
Keyword(s):  
Nox Reduction ◽  
Combustion Characteristics ◽  
Nox Emission ◽  
Air Concentration ◽  
New Approach ◽  
Lean Combustion ◽  
Study Results ◽  
Firing Furnace ◽  
Secondary Air ◽  
Outer Primary

A swirling burner with a variable inner secondary air (ISA) flaring angle β is proposed and a laboratory scale opposed-firing furnace is built. Temperature distribution and NOx emission are designedly measured. The combustion characteristics affected by variable β are experimentally evaluated from ignition and burnout data. Meanwhile, NOx reduction by the variable β is analyzed through emissions measurements. Different inner/outer primary coal-air concentration ratios γ, thermal loads and coal types are considered in this study. Results indicate that β variation provides a new approach to promote ignition and burnout, as well as NOx emission reduction under conditions of fuel rich/lean combustion and load variation. The recommended β of a swirling burner under different conditions is not always constant. The optimal βopt of the swirling burner under all conditions for different burning performance are summarized in the form of curves, which could provide reference for exquisite combustion adjustment.

Experimental and Numerical Investigation of a Planar Combustor Sector at Realistic Operating Conditions

2000 ◽  
Author(s):  
Thomas Behrendt ◽  
Martin Carl ◽  
Christian Fleing ◽  
Matthias Frodermann ◽  
Johannes Heinze ◽  
...  
Keyword(s):  
Reduction Potential ◽  
Measurement Techniques ◽  
Nox Reduction ◽  
Mie Scattering ◽  
Isothermal Flow ◽  
Operating Conditions ◽  
Aerospace Research ◽  
Air Jets ◽  
Secondary Air ◽  
German Aerospace

Results of an ongoing collaboration between the engine manufacturer MTU and the German aerospace research center DLR on the NOx reduction potential of conventional combustors are reported. A program comprising optical sector combustor measurements at 1, 6 and 15 bars and CFD calculations is carried out. The aims are to gather information in the combustor at realistic operating conditions, to understand the differences between the sector flow field and data from tubular combustors, to verify the used CFD and to discover the benefits and limitations of the applied optical diagnostics. Selected results of measurement and calculation of the isothermal flow and of measurements at 6 bars and 700 K at a rich-lean and overall lean AFR are reported. The used measurement techniques were LDA, PDA, Mie scattering on kerosene, Quantitative Light Scattering, OH* Chemiluminescence and LIF on OH. The measurements were able to confirm the intended quick and homogeneous mixing of the three staggered rows of secondary air jets.

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