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.

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.

Shear Layer Mixing for Low Emission Gas Turbine Primary Zones

1984 ◽  
Author(s):  
N. A. Al-Dabbagh ◽  
G. E. Andrews ◽  
R. Manorharan
Keyword(s):  
Shear Layer ◽  
Gas Turbine ◽  
Fuel Injection ◽  
Flame Temperature ◽  
Stability Margin ◽  
Air Injection ◽  
Flame Stability ◽  
Nox Emissions ◽  
Primary Zone ◽  
Air Mixing

Shear layer turbulent fuel and air mixing has been utilised in a simulated gas turbine primary zone combustor. Two methods of fuel injection and two values of the number of air injection holes have been investigated at a constant pressure loss of 4% at a reference Mach number of 0.047. The method of fuel injection and the number of air injection holes was found to influence the flame stability and NOx emissions. A large number of holes produced much higher NOx emissions which was not compensated for by the ability to operate at weaker equivalence ratios due to the greater flame stability. An optimum primary zone operating condition, for very low NOx and high combustion efficiencies involving a flame temperature of approximately 1600K was identified and there was a wide flame stability margin on this condition.

Low NOx Primary Zones Using Jet Mixing Shear Layer Combustion

1988 ◽  
Author(s):  
U. S. Abdul Hussain ◽  
G. E. Andrews ◽  
W. G. Cheung ◽  
A. R. Shahabadi
Keyword(s):  
Natural Gas ◽  
Shear Layer ◽  
Gas Turbines ◽  
Scale Up ◽  
Combustion Efficiency ◽  
Operating Conditions ◽  
Nox Emissions ◽  
Fuel Injector ◽  
Jet Mixing ◽  
Primary Zone

An interacting radial and axial multi jet shear layer combustion system is described that has the rapid fuel and air mixing characteristics necessary for low NOx emissions. The radial jet has the fuel mixed with a proportion of the total primary zone flow and a 30% proportion was investigated. This radial jet was fuel rich at most primary zone operating conditions and ensured a flame stability far superior to the premixed situation. The scale up of the design from a 76mm to a 140mm diameter combustor was investigated. It was demonstrated that the distance the radial jet travelled before encountering the rapid mixing with the axial jets, had a strong influence on the combustion efficiency and NOx emissions. For both the 76 and 140mm combustors it was shown that the NOx emissions with propane were 50% greater than those for natural gas. It was also demonstrated that the low NOx emissions of the 76mm system were retained in the larger combustor with the same single central fuel injector design. There was a significant increase in NOx for some 140mm combustor configurations, but the emissions corrected to 15% oxygen below 10ppm were demonstratred, with a high combustion efficiency. The design thus demonstrated, in a practical combustor size, the potential for a dry solution to the NOx emissions problem of natural gas fired industrial gas turbines.

Experimental Assessment of the Emissions Benefits of a Ceramic Gas Turbine Combustor

1996 ◽  
Author(s):  
K. O. Smith ◽  
A. Fahme
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Flow Distribution ◽  
Operating Conditions ◽  
Nox Emissions ◽  
Fuel Injector ◽  
Gas Turbine Combustor ◽  
Experimental Assessment ◽  
Industrial Gas Turbine ◽  
Combustor Liner

Three subscale, cylindrical combustors were rig tested on natural gas at typical industrial gas turbine operating conditions. The intent of the testing was to determine the effect of combustor liner cooling on NOx and CO emissions. In order of decreasing liner cooling, a metal louvre-cooled combustor, a metal effusion-cooled combustor, and a backside-cooled ceramic (CFCC) combustor were evaluated. The three combustors were tested using the same lean-premixed fuel injector. Testing showed that reduced liner cooling produced lower CO emissions as reaction quenching near the liner wall was reduced. A reduction in CO emissions allows a reoptimization of the combustor air flow distribution to yield lower NOx emissions.

Development of a Natural Gas-Fired, Ultra-Low NOx Can Combustor for an 800 KW Gas Turbine

1991 ◽  
Author(s):  
K. O. Smith ◽  
A. C. Holsapple ◽  
H. K. Mak ◽  
L. Watkins
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Premixed Combustion ◽  
Experimental Results ◽  
Nox Emissions ◽  
Variable Geometry ◽  
Lean Premixed Combustion ◽  
Full Load ◽  
Primary Zone ◽  
Lean Premixed

The experimental results from the rig testing of an ultra-low NOx, natural gas-fired combustor for an 800 to 1000 kw gas turbine are presented. The combustor employed lean-premixed combustion to reduce NOx emissions and variable geometry to extend the range over which low emissions were obtained. Testing was conducted using natural gas and methanol. Testing at combustor pressures up to 6 atmospheres showed that ultra-low NOx emissions could be achieved from full load down to approximately 70% load through the combination of lean-premixed combustion and variable primary zone airflow.

Numerical Investigations of NOx Emissions of a Partially Premixed Burner for Natural Gas Operations in Industrial Gas Turbine

2014 ◽  
Author(s):  
Alessandro Innocenti ◽  
Antonio Andreini ◽  
Andrea Giusti ◽  
Bruno Facchini ◽  
Matteo Cerutti ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Turbulent Combustion ◽  
Fuel Injection ◽  
Formation Rate ◽  
Operating Conditions ◽  
Combustion Model ◽  
Nox Emissions ◽  
Air Concentration ◽  
Partially Premixed ◽  
Industrial Gas Turbine

In the present paper a numerical analysis of a low NOx partially premixed burner for industrial gas turbine applications is presented. The first part of the work is focused on the study of the premixing process inside the burner. Standard RANS CFD approach was used: k–ε turbulence model was modified and calibrated in order to find a configuration able to fit available experimental profiles of fuel/air concentration at the exit of the burner. The resulting profiles at different test points have been used to perform reactive simulations of an experimental test rig, where exhaust NOx emissions were measured. An assessment of the turbulent combustion model was carried out with a critical investigation of the expected turbulent combustion regimes in the system and taking into account the partially premixed nature of the flame due to the presence of diffusion type pilot flames. A reliable numerical setup was discovered by comparing predicted and measured NOx emissions at different operating conditions and at different split ratio between main and pilot fuel. In the investigated range, the influence of the premixer in the NOx formation rate was found to be marginal if compared with the pilot flame one. The calibrated numerical setup was then employed to explore possible modifications to fuel injection criteria and fuel split, with the aim of minimizing exhaust NOx emissions. This preliminary numerical screening of alternative fuel injection strategies allowed to define a set of advanced configurations to be investigated in future experimental tests.

Jet Shear Layer Size and Number Influences on Grid Plate Direct Fuel Injection Shear Layer Mixing Low NOx Gas Turbine Combustion With Fuel Staging for Power Turn Down

2008 ◽  
Author(s):  
Gordon E. Andrews ◽  
S. A. R. Ahmed
Keyword(s):  
Shear Layer ◽  
Gas Turbine ◽  
Fuel Injection ◽  
Scale Up ◽  
Shear Layers ◽  
Inlet Temperature ◽  
Nox Emissions ◽  
Round Jet ◽  
Fuel Staging ◽  
Four Levels

The scale up of jet shear layer low NOx concepts for compact gas turbine applications is considered using natural gas as the fuel with all experiments at one atmosphere pressure and 600K air inlet temperature. A 76mm diameter cylindrical combustor with 4 round jet shear layers was compared with a near double scale combustor with 140mm diameter and 4 round jet shear layers with the same total blockage as for the smaller combustor. This is compared with 16 round jet shear layers of the same diameter as for the smaller combustor. The shear layer air holes were fuelled by eight radial inward fuel injection holes in each shear layer jet. All three designs had acceptable combustion efficiencies, but the NOx emissions were considerably higher for the 4 shear layer design in the larger combustion. When the same shear layer hole size was used and the number increased in the larger combustor the NOx emissions were identical. Changing the shape of the hole from circulat to slot for the same area, considerably reduced the NOx in the four hole 76mm combustor, but had little effect on the 16 hole 140mm combustor. Fuel staging within the array of shear layers was successfully demonstrated for four levels of fuel staging. There was some intermixing of air from the unfuelled jets, but this had only a small effect on the combustion efficiency and flame stability. A practical range of simulated power turndown was demonstrated with little NOx penalty. This was achieved with no wall between the staged shear layer regions and hence leads to very compact combustor designs.

Design and Testing of an Ultra-Low NOx Gas Turbine Combustor

1986 ◽  
Author(s):  
Kenneth O. Smith ◽  
Leonard C. Angello ◽  
F. Richard Kurzynske
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Catalytic Reduction ◽  
Water Injection ◽  
Nox Emissions ◽  
Combustion System ◽  
Gas Turbine Combustor ◽  
Program Goal ◽  
Primary Zone ◽  
Design And Testing

The design and initial rig testing of an ultra-low NOx gas turbine combustor primary zone are described. A lean premixed, swirl-stabilized combustor was evaluated over a range of pressures up to 10.7 × 105 Pa (10.6 atm) using natural gas. The program goal of reducing NOx emissions to 10 ppm (at 15% O2) with coincident low CO emissions was achieved at all combustor pressure levels. Appropriate combustor loading for ultra-low NOx operation was determined through emissions sampling within the primary zone. The work described represents a first step in developing an advanced gas turbine combustion system that can yield ultra-low NOx levels without the need for water injection and selective catalytic reduction.

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.

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.

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