Radial Swirlers With Peripheral Fuel Injection for Ultra-Low NOx Emissions

1990 ◽  
Author(s):  
H. S. Al Kabie ◽  
G. E. Andrews
Keyword(s):  
Natural Gas ◽  
Recirculation Zone ◽  
Fuel Injection ◽  
Air Flow ◽  
Inlet Temperature ◽  
Nox Emissions ◽  
Gas Oil ◽  
Primary Zone ◽  
Wall Injection

A 76mm outlet diameter radial swirler with a dump expansion into a 140mm diameter combustor was investigated with a simulated 43% primary zone air flow at a 600K inlet temperature and one bar pressure. Two modes of peripheral fuel injection were investigated: at the 76mm swirler outlet and at the 140mm combustor wall just downstream of the swirler. This 140mm wall injector resulted in fuel injection into the swirler expansion outer recirculation zone. It was shown that the 140mm wall injection gave much higher NOx emissions than for the 76mm swirler outlet injector. These results were compared with other methods of fuel injection and the 76mm peripheral injection was shown to have superior NOx emissions than vane passage injection for all fuels except gas oil. Ultra low NOx emissions of 1ppm with 20 ppm CO, both at 15% oxygen, were demonstrated for propane and natural gas.

scholarly journals Ultra Low NOx Emissions for Gas and Liquid Fuels Using Radial Swirlers

1989 ◽  
Author(s):  
H. S. Alkabie ◽  
G. E. Andrews
Keyword(s):  
Gas Turbines ◽  
Fuel Injection ◽  
Air Flow ◽  
Combustion Efficiency ◽  
Liquid Fuels ◽  
Inlet Temperature ◽  
Flame Stability ◽  
Nox Emissions ◽  
Gas Oil ◽  
Industrial Gas Turbines

Curved blade radial swirlers using all the primary air were investigated with applications to lean burning gas turbine combustor primary zones with low NOx emissions. Two modes of fuel injection were compared, central and radial swirler pássage injection for gaseous and liquid fuels. Both fuel systems produced low NOx emissions but the upstream mixing in the swirler passages resulted in ultra low NOx emissions. A 140mm diameter atmospheric pressure combustor was used with 43% of the combustor air flow into the primary zone through the radial swirler. Radial gas composition measurements at various axial distances were made and these showed that the flame stability and NOx emissions were controlled by differences in local mixing at the base of the swirling shear layer downstream of the swirler outlet. For radial passage fuel injection it was found that a very high combustion efficiency was obtained for both propane and liquid fuels at 400K and 600K inlet temperatures. The flame stability, although worse than for central fuel injection was considerably better than for a premixed system. The NOx emissions at one bar pressure and 600K inlet temperature, compatible with a high combustion efficiency, for propane and kerosene were 3 and 6 ppm at 15% oxygen. For Gas Oil the NOx emissions were higher, but were still very low at 12ppm. Assuming a square root dependence of NOx on pressure these results indicate that NOx emissions of 48ppm for Gas Oil and less than 12ppm for gaseous fuels could be achieved at 16 bar pressure, which is typical of recent industrial gas turbines. High air flow radial swirlers with passage fuel injection have the potential for a dry solution to the NOx emissions regulations.

Lean Low NOx Primary Zones Using Radial Swirlers

1988 ◽  
Author(s):  
H. S. Alkabie ◽  
G. E. Andrews ◽  
N. T. Ahmad
Keyword(s):  
Natural Gas ◽  
Recirculation Zone ◽  
Fuel Injection ◽  
Swirling Flow ◽  
Combustion Efficiency ◽  
Flame Stability ◽  
Nox Emissions ◽  
Primary Zone ◽  
Outer Expansion ◽  
Curved Blade

Swirling flow primary zones with between 30% and 60% simulated primary zone air flow were investigated using curved blade radial swirlers. Two radial swirlers were compared with the same open area but different outlet diameters, d, giving different expansion ratios, D/d, from the swirler to the combustor diameter, D. Two combustors were used, 76 mm and 140 mm diameter, the larger one corresponding to the size of several gas turbine can combustors. There was no influence of D/d on the weak extinction. It was demonstrated that an adequate efficiency was not achieved in the weak region until there was a significant outer expansion and associated recirculation zone. It was shown that these systems with central gaseous fuel injection had good flame stability with very low NOx emissions. Propane and natural gas were compared and the NOx emissions were 50% lower with natural gas. The optimum NOx emissions, compatible with a high combustion efficiency, were close to 10 ppm NOx emissions corrected to 15% oxygen.

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.

Jet Shear Layer Turbulent Diffusion Flames for Ultralow NOx Emissions

1992 ◽  
Vol 114 (1) ◽  
pp. 55-62 ◽  
Author(s):  
A. F. Ali Al-Shaikhly ◽  
G. E. Andrews ◽  
C. O. Aniagolu
Keyword(s):  
Natural Gas ◽  
Shear Layer ◽  
Gas Turbine ◽  
Fuel Injection ◽  
Diffusion Flames ◽  
Stability Margin ◽  
Operating Conditions ◽  
Nox Emissions ◽  
Turbulent Diffusion Flames ◽  
Primary Zone

Direct fueling of each shear layer generated by an array of holes in a grid plate was shown to have ultralow NOx emissions combined with a good flame stability, compared with a premixed system. Two methods of fuel injection were investigated that had opposite NOx/stability characteristics. Four shear layers in a 76-mm combustor were used at gas turbine primary zone operating conditions with 60 percent simulated primary zone air at one bar pressure. The fuels used were propane and natural gas and a minimum NOx emission of 2.5 ppm at 15 percent oxygen, compatible with a 0.1 percent inefficiency, was demonstrated for natural gas with a reasonable stability margin. These designs have the potential for a dry NOx solution to any current or proposed gas turbine NOx regulation for natural gas.

Centrifugal Mixing in Gas and Liquid Fuelled Lean Swirl Stabilized Primary Zones

1985 ◽  
Author(s):  
N. T. Ahmad ◽  
G. E. Andrews ◽  
M. Kowkabi ◽  
S. F. Sharif
Keyword(s):  
Fuel Injection ◽  
Combustion Efficiency ◽  
Nox Emissions ◽  
Liquid Droplets ◽  
Gas Oil ◽  
Swirl Number ◽  
Gaseous Fuels ◽  
Wall Injection ◽  
Centrifugal Action

A flat bladed axial swirler of 0.7 swirl number has been investigated in a 76 mm diameter combustor with all the combustion air passing through the swirler. Both liquid and gaseous fuels were used with eight injection points on the combustor wall just downstream of the swirler. This wall injection was aimed at the exploitation of centrifugal mixing forces acting on the burnt gas pockets at the wall to send them towards the centre and to displace higher density unburnt gas pockets to the wall and so promote mixing. For both kerosene and propane fuels there was a significant improvement in the combustion efficiency and NOX emissions compared with central fuel injection. For kerosene the NOX emissions were lower than for propane and very close to those for premixed fuel and air. However, for gas oil there was little improvement in performance with wall injection compared with central. This was attributed to the slower vaporisation rate with gas oil coupled with the centrifugal action on the liquid droplets with central injection.

Influence of Fuel Injection Location in a Small Radial Swirler Low NOx Combustor for Micro Gas Turbine Applications

2019 ◽  
Author(s):  
Gordon E. Andrews ◽  
Su Kim
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Fuel Injection ◽  
Nox Emissions ◽  
Fuel Injector ◽  
Micro Gas Turbine ◽  
Optimum Position ◽  
Pilot Fuel ◽  
Wall Injection ◽  
Injection Location

Abstract The influence of fuel injection location in a low NOx (1) micro-gas turbine [MGT] in the ∼50kWe (kW electric) size range was investigated, for NG and propane, to extend the power turn down using a pilot fuel injector. The low NOx main combustor (1) was a radial swirler with vane passage fuel injection and had ultra-low NOx emissions of 3ppm at 15% O2 at 1800K with natural gas, NG at a combustion intensity of 11.2 MW/m2bara (MW thermal). This was a 40mm diameter outlet eight bladed radial swirler in a 76mm diameter combustor, investigated at 740K air temperature at atmospheric pressure. However, power turn down was poor and the present work was undertaken to determine the optimum position of pilot fuel injection that would enable leaner mixtures to be burned at low powers. Central injection of pilot fuel was investigated using 8 radial outward holes. This was compared with pilot fuel injected at the 76mm wall just downstream of the 40mm swirler outlet. It was show that the central injection pilot was poor with a worse weak extinction than for radial passage fuel injection. The 76mm outlet wall injection was much more successful as a pilot fuel location and had a weak extinction of 0.18Ø compared with 0.34Ø for vane passage fuel injection. NOx emissions were higher for wall fuel injection, but were still relatively low at 16ppm at 15% oxygen for natural gas. This indicates that wall fuel injection could be combined with vane passage fuel injection to improve the micro-gas turbine low NOx performance across the power range.

scholarly journals Jet Shear Layer Turbulent Diffusion Flames for Ultra-Low NOx Emissions

1990 ◽  
Author(s):  
A. F. Ali Al-Shaikhly ◽  
G. E. Andrews ◽  
C. O. Aniagolu
Keyword(s):  
Natural Gas ◽  
Shear Layer ◽  
Gas Turbine ◽  
Fuel Injection ◽  
Diffusion Flames ◽  
Stability Margin ◽  
Operating Conditions ◽  
Nox Emissions ◽  
Turbulent Diffusion Flames ◽  
Primary Zone

Direct fuelling of each shear layer generated by an array of holes in a grid plate was shown to have ultra-low NOx emissions combined with a good flame stability, compared with a premixed system. Two methods of fuel injection were investigated that had opposite NOx/stability characteristics. Four shear layers in a 76 mm combustor were used at gas turbine primary zone operating conditions with 60% simulated primary zone air at one bar pressure. The fuels used were propane and natural gas and a minimum NOx emission of 2.5 ppm at 15% oxygen, compatible with a 0.1% inefficiency, was demonstrated for natural gas with a reasonable stability margin. These designs have the potential for a dry NOx solution to any current or proposed gas turbine NOx regulation for natural gas.

Co-Firing of Kerosene and Biodiesel With Natural Gas in a Low NOx Radial Swirl Combustor

2012 ◽  
Author(s):  
Mohamed A. Altaher ◽  
Hu Li ◽  
Gordon E. Andrews
Keyword(s):  
Natural Gas ◽  
Fuel Injection ◽  
Liquid Fuels ◽  
Inlet Temperature ◽  
Nox Emissions ◽  
Fuel Injector ◽  
Gas Combustion ◽  
Swirl Combustor ◽  
Low Nox Combustion ◽  
Natural Gas Combustion

Co-firing of biodiesel with natural gas, using a low NOx gas turbine combustor was investigated and compared with the equivalent natural gas and kerosene co-firing. The work was carried out at atmospheric pressure with 600K air inlet temperature and used an 8 vane radial swirler. Well mixed natural gas combustion was achieved using radially inward gas fuel injection through the wall of the swirler outlet throat. The biofuel was injected centrally using an eight hole radial fuel injector. This central fuel injector location forms a good pilot flame for natural gas low NOx combustion and was the only fuel injection location that biodiesel combustion could be stabilised. This was because central fuel injection was into the hot recirculating gases on the centreline that is a feature of radial swirl lean low NOX combustion. The biodiesel results were compared with equivalent tests for kerosene as the central injection fuel. Co-firing was investigated with a low level of main natural gas combustion that was held constant and the equivalence ratio was increased using the central injection of biodiesel or kerosene. Operation on kerosene with no acoustic problem was demonstrated up to Ø = 0.95. Three natural gas initial equivalence ratios were investigated with co-firing of liquid fuels, Ø = 0.18, 0.22 and 0.34. A key benefit of operating with hotter premixed combustion with natural gas was that the overall Ø at which stable low CO and HC operation could be achieved with biodiesel was extended to leaner overall Ø. The NOx emissions in this co-firing mode were remarkably low for relatively rich overall mixtures, where conventional single fuel main injection on natural gas gave higher NOx emissions.

Radial Swirler Designs for Ultra-Low NOx Gas Turbine Combustion

2008 ◽  
Author(s):  
Gordon E. Andrews ◽  
Nick Escott ◽  
Michael C. Mkpadi
Keyword(s):  
Gas Turbine ◽  
Cross Sections ◽  
Fuel Injection ◽  
Expansion Ratio ◽  
Nox Emissions ◽  
Air Inlet ◽  
Primary Zone ◽  
Air Mixing ◽  
Wall Injection ◽  
Injection Location

Four radial swirler vane passage designs were investigated for low NOx lean well mixed combustion of natural gas at simulated gas turbine primary zone conditions in terms of reference velocities and 600–740K air inlet temperatures at atmospheric pressure. Each radial swirler had eight vane passages and the four passage designs were curved, aerodynamic tapered flat bladed, rectangular and circular passage cross sections. The first two designs had an area that decreased towards the passage outlet and the last two designs were constant area vane passages. The swirler exit diameter d (76mm) to the combustor diameter D (140mm) expansion ratio, D/d, was 1.84. Three methods of fuel injection were investigated: eight single fuel holes per radial vane passage injection, swirler outlet throat 8 hole wall injection and 8 hole radially outward central injection. The results showed that the different radial swirler designs did not have a strong influence on the NOx emissions, compared with the stronger influence of the fuel injection location. All radial vane swirler passage designs gave minimum NOx emissions in the 1–2 ppm range. The radial swirler design influenced which fuel injection location, passage or exit throat wall, gave the lowest NOx emissions. The results were compared with the CPMCP ultra-low NOx emissions concept to show that the present rapid fuel and air mixing radial swirler results are equal to the best premixed low NOx designs.

Development of a Phenomenological Combustion Simulation for a Dual Fuel Engine

2001 ◽  
Author(s):  
Yafeng Liu ◽  
Stuart R. Bell ◽  
K. Clark Midkiff
Keyword(s):  
Natural Gas ◽  
Diesel Fuel ◽  
Fuel Injection ◽  
Air Entrainment ◽  
Dual Fuel ◽  
Nox Emissions ◽  
Cycle Simulation ◽  
Specific Performance ◽  
Combustion Simulation ◽  
Reduce Emissions

Abstract A phenomenological cycle simulation for a dual fuel engine has been developed to mathematically simulate the significant processes of the engine cycle, to predict specific performance parameters for the engine, and to investigate approaches to improve performance and reduce emissions. The simulation employs two zones (crevice and unburned) during the processes of exhaust, intake, compression before fuel injection starts, and expansion after combustion ends. From the start of fuel injection to the end of combustion, several, zones are utilized to account for crevice flow, diesel fuel spray, air entrainment, diesel fuel droplet evaporation, ignition delay, flame propagation, and combustion quenching. The crevice zone absorbs charge gas from the cylinder as pressure increases, and releases mass back into the chamber as pressure decreases. Some crevice mass released during late combustion may not be oxidized, resulting in emissions of hydrocarbon and carbon monoxide. Quenching ahead of the flame front may leave additional charge unburned, yielding high methane emissions. Potential reduction of engine-out NOx emissions with natural gas fueling has also been investigated. The higher substitution of natural gas in the engine produces less engine-out NOx emissions. This paper presents the development of the model, baseline predictions, and comparisons to experimental measurements performed in a single-cylinder Caterpillar 3400 series engine.

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