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.

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.

Development of a Low NOx Combustor for 300kW-Class Ceramic Gas Turbine (CGT302)

1998 ◽  
Author(s):  
A. Okuto ◽  
T. Kimura ◽  
I. Takehara ◽  
T. Nakashima ◽  
Y. Ichikawa ◽  
...  
Keyword(s):  
Research And Development ◽  
Gas Turbine ◽  
Flow Rate ◽  
Gas Turbines ◽  
Combustion Efficiency ◽  
Development Project ◽  
Pollutant Emissions ◽  
Inlet Temperature ◽  
Outlet Temperature ◽  
Nox Emissions

Research and development project of ceramic gas turbines (CGT) was started in 1988 promoted by the Ministry of International Trade and Industry (MITI) in Japan. The target of the CGT project is development of a 300kW-class ceramic gas turbine with a 42 % thermal efficiency and a turbine inlet temperature (TIT) of 1350°C. Three types of CGT engines are developed in this project. One of the CGT engines, which is called CGT302, is a recuperated two-shaft gas turbine for co-generation use. In this paper, we describe the research and development of a combustor for the CGT302. The project requires a combustor to exhaust lower pollutant emissions than the Japanese regulation level. In order to reduce NOx emissions and achieve high combustion efficiency, lean premixed combustion technology is adopted. Combustion rig tests were carried out using this combustor. In these tests we measured the combustor performance such as pollutant emissions, combustion efficiency, combustor inlet/outlet temperature, combustor inlet pressure and pressure loss through combustor. Of course air flow rate and fuel flow rate are controlled and measured, respectively. The targets for the combustor such as NOx emissions and combustion efficiency were accomplished with sufficient margin in these combustion rig tests. In addition, we report the results of the tests which were carried out to examine effects of inlet air pressure on NOx emissions here.

Reduced NOx Diffusion Flame Combustors for Industrial Gas Turbines

2000 ◽  
Vol 123 (4) ◽  
pp. 757-765 ◽  
Author(s):  
A. S. Feitelberg ◽  
V. E. Tangirala ◽  
R. A. Elliott ◽  
R. E. Pavri ◽  
R. B. Schiefer
Keyword(s):  
Diffusion Flame ◽  
Gas Turbines ◽  
Turbulent Flame ◽  
Steam Injection ◽  
Flame Length ◽  
Inlet Temperature ◽  
Nox Emissions ◽  
Complete Combustion ◽  
Industrial Gas Turbines ◽  
Fuel Nozzle

This paper describes reduced NOx diffusion flame combustors that have been developed for both simple cycle and regenerative cycle MS3002 and MS5002 gas turbines. Laboratory tests have shown that when firing with natural gas, without water or steam injection, NOx emissions from the new combustors are about 40 percent lower than NOx emissions from the standard combustors. CO emissions are virtually unchanged at base load, but increase at part load conditions. Commercial demonstration tests have confirmed the laboratory results. The standard combustors on both the MS3002 and MS5002 gas turbine are cylindrical cans, approximately 10.5 inches (27 cm) in diameter. A single fuel nozzle is centered at the inlet to each can and produces a swirl stabilized diffusion flame. The walls of the cans are louvered for cooling, and contain an array of mixing and dilution holes that provide the air needed to complete combustion and dilute the burned gas to the desired turbine inlet temperature. The MS3002 turbine is equipped with six combustor cans, while the MS5002 turbine is equipped with twelve combustors. The new, reduced NOx emissions combustors (referred to as a “lean head end,” or LHE, combustors) retain all of the key features of the conventional combustors; the only major difference is the arrangement of the mixing and dilution holes in the cylindrical combustor cans. By optimizing the number, diameter, and location of these holes, NOx emissions can be reduced considerably. Minor changes are also sometimes made to the combustor cap. The materials of construction, pressure drop, and fuel nozzle are all unchanged. The differences in NOx emissions between the standard and LHE combustors, as well as the variations in NOx emissions with firing temperature, are well correlated using turbulent flame length arguments. Details of this correlation are presented.

scholarly journals Conical Grid Plate Flame Stabilizers for Combustor Primary Zones

1985 ◽  
Author(s):  
A. F. Ali ◽  
G. E. Andrews
Keyword(s):  
Residence Time ◽  
Fuel Injection ◽  
Combustion Efficiency ◽  
Shear Layers ◽  
Injection System ◽  
Fuel Injection System ◽  
Nox Emissions ◽  
Fuel Injector ◽  
Primary Zone ◽  
Grid Plate

Emission results are presented for a jet shear layer flame stabiliser design consisting of a 90° conical flame stabiliser with an array of holes and a central annular vaporiser fuel injection system. This design was tested with premixed propane and air and with direct propane injection into the vaporiser at two blockages and approach velocities. The results showed that an array of jet shear layers could be fuelled by a single fuel injector without incurring excessive NOx emissions. An increase in the primary zone residence time was found to result in an improved combustion efficiency, with no increase in NOx, provided that the stabiliser blockage was increased to maintain the pressure loss.

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.

Small Radial Swirler Low NOx Combustors for Micro Gas Turbine Applications

2017 ◽  
Author(s):  
Gordon E. Andrews ◽  
Myeong Kim
Keyword(s):  
Heat Release ◽  
Gas Turbines ◽  
Fuel Injection ◽  
Thermal Power ◽  
Inlet Temperature ◽  
Micro Gas Turbine ◽  
Air Inlet ◽  
Primary Zone ◽  
Flame Development ◽  
Scale Down

There is a growing interest in micro-gas turbines for distributed electric power production. This work examines the scale down of a successful low NOx radial swirler from a combustor of 140mm diameter to one of 76mm diameter, suitable for micro-gas turbines in the 30–100kW electric size range. A 40mm outlet eight bladed radial swirler was investigated for four radial swirler vane depths from 30.5mm to 12.2mm and a constant pressure loss of 2.7% at different reference Mach numbers or residence times. For a 740K inlet temperature and 0.6 equivalence ratio, Ø, these gave combustor thermal loadings at atmospheric pressure from 33 to 62 kW and heat release of 7–14 MW/m2bar. The small radial swirlers had lean stable flames with near lean flammability weak extinction. The vane passage single hole fuel injection achieved NOx emissions of 1–5ppm at 15% oxygen, 740K air inlet temperature and 1700K primary zone temperature, with <10ppm CO. The 1ppm NOx was for the smallest vane depth and lowest thermal power. The higher NOx for the larger heat release swirler designs were due to the longer flame development and a greater formation of prompt NOx, due to the high UHC for most of the flame development.

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.

Hydrogen Combustion at High Combustor Airflow Using an Impinging Jet Flame Stabiliser With No Flashback and Low NOx

2012 ◽  
Author(s):  
Gordon E. Andrews ◽  
Mohamed A. Altaher ◽  
Hu Li
Keyword(s):  
Gas Turbines ◽  
Hydrogen Combustion ◽  
Inlet Temperature ◽  
Nox Emissions ◽  
Fuel Injector ◽  
Jet Flame ◽  
Air Jets ◽  
Industrial Gas Turbines ◽  
Stability Issue ◽  
Thermal Nox

The feasibility of hydrogen as a fuel for industrial gas turbines with low NOx emissions was investigated. Conventional well mixed flame stabilisers are difficult to use with 100% hydrogen owing to the flash back problem, which is potentially seven times worse for hydrogen due to its higher reactivity. This work was carried out using a rapidly mixed Jet Mix design, which had previously been investigated with NG and propane. This consisted of eight radial air jets into which the fuel was injected on their centrelines. These radial jets impinged into eight axial air jets which carried the bulk of the combustion air. Radial jet air flow proportions of 6.5% and 20% were investigated at an overall pressure loss at M1 = 0.047 of 4.3% in a 76mm diameter combustor. The reference Mach number, M1 of 0.047 represents all the compressor exit air entering the combustor with no dilution air. Very lean mixtures are required for low NOx emissions and there is no flame stability issue with hydrogen combustion, so all power turndown can be achieved with one main fuel injector. An inlet temperature of 600K was used at atmospheric pressure and the flames were lean enough to have temperatures where there was no pressure dependence of thermal NOx. For 6.5% radial air NOx emissions of 25ppm at 15% oxygen were demonstrated at 1800K and lower NOx at lower turbine entry temperatures.

Reduced NOx Diffusion Flame Combustors for Industrial Gas Turbines

2000 ◽  
Author(s):  
Alan S. Feitelberg ◽  
Venkat E. Tangirala ◽  
Richard A. Elliott ◽  
Roointon E. Pavri ◽  
Richard B. Schiefer
Keyword(s):  
Diffusion Flame ◽  
Gas Turbines ◽  
Turbulent Flame ◽  
Steam Injection ◽  
Flame Length ◽  
Inlet Temperature ◽  
Nox Emissions ◽  
Complete Combustion ◽  
Industrial Gas Turbines ◽  
Fuel Nozzle

This paper describes reduced NOx, diffusion flame combustors that have been developed for both simple cycle and regenerative cycle MS3002 and MS5002 gas turbines. Laboratory tests have shown that when firing with natural gas, without water or steam injection, NOx emissions from the new combustors are about 40% lower than NOx emissions from the standard combustors. CO emissions are virtually unchanged at base load, but increase at part load conditions. Commercial demonstration tests have confirmed the laboratory results. The standard combustors on both the MS3002 and MS5002 gas turbine are cylindrical cans, approximately 10.5 inches (27 cm) in diameter. A single fuel nozzle is centered at the inlet to each can and produces a swirl stabilized diffusion flame. The walls of the cans are louvered for cooling, and contain an array of mixing and dilution holes that provide the air needed to complete combustion and dilute the burned gas to the desired turbine inlet temperature. The MS3002 turbine is equipped with six combustor cans, while the MS5002 turbine is equipped with twelve combustors. The new, reduced NOx emissions combustors (referred to as a “lean head end”, or LHE, combustors) retain all of the key features of the conventional combustors; the only major difference is the arrangement of the mixing and dilution holes in the cylindrical combustor cans. By optimizing the number, diameter, and location of these holes, NOx emissions can be reduced considerably. Minor changes are also sometimes made to the combustor cap. The materials of construction, pressure drop, and fuel nozzle are all unchanged. The differences in NOx emissions between the standard and LHE combustors, as well as the variations in NOx emissions with firing temperature, are well correlated using turbulent flame length arguments. Details of this correlation are presented.

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