Stagnation-Point Reverse-Flow Combustor Performance With Liquid Fuel Injection

2006 ◽  
Author(s):  
John Crane ◽  
Yedidia Neumeier ◽  
Jeff Jagoda ◽  
Jerry Seitzman ◽  
Ben T. Zinn
Keyword(s):  
Stagnation Point ◽  
Power Density ◽  
Gas Turbines ◽  
Fuel Injection ◽  
Reverse Flow ◽  
Combustion Process ◽  
Liquid Fuels ◽  
Fuel Injector ◽  
Low Velocity ◽  
Pressure Losses

This paper describes an investigation of the performance of the recently developed ultra low emissions, Stagnation-Point Reverse-Flow (SPRF) Combustor when burning liquid fuels (Jet-A and heptane). This study has been undertaken because of the need to burn liquid fuels with low emissions in gas turbines that are used, for example, in aircraft engines, land-based power generation, and marine applications. In contrast with state of the art combustors, in which the reactants and products enter and leave the combustor through opposite ends of the combustor, the reactants and products enter and leave the SPRF combustor through the same plane opposite a closed end. The design of the SPRF combustor allows mixing of reactants with hot combustion products and radicals within the combustor, prior to combustion. Thus, no external premixing of fuel and air is required. Additionally, since the air and fuel enter opposite the closed end of the combustor, they must stagnate near the closed end, thus establishing a region of low velocity just upstream of the closed end that helps stabilize the combustion process. This apparently produces a low temperature, stable, distributed reaction zone. Previous studies with the SPRF combustor investigated its performance while burning natural gas. This paper presents the results of SPRF combustor studies using liquid fuels, both heptane and Jet-A. The performance of the combustor was investigated using an airblast fuel injector, which is suitable for the low fuel flow rates used in laboratory experiments. To reduce pressure losses across the injector, a diffuser was incorporated into the airblast injector. It was found that stable combustor operation was achieved burning Jet-A with emissions of less than 1 ppm NOx and 5 ppm CO, pressure losses less than 5 percent, and a power density on the order of 10 MW/m3 in atmospheric pressure. This power density would linearly scale to 300 MW/m3 in a combustor at a pressure of 30 atmospheres.

The Fuel Problem in Gas Turbines

1948 ◽  
Vol 159 (1) ◽  
pp. 220-229 ◽  
Author(s):  
Peter Lloyd
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Fuel Injection ◽  
Combustion Process ◽  
Liquid Fuels ◽  
Practical Significance ◽  
Graphical Form ◽  
Elementary Analysis ◽  
Fuel Characteristics ◽  
Ignition Characteristics

Accepting the principle that the gas turbine is potentially capable of consuming all fuels, the author proceeds to investigate the range of possible liquid fuels and the fuel characteristics of greatest practical significance. Whilst certain properties of liquid fuels—as for example, ignition characteristics and molecular structure—are so complex that no correlation with gas-turbine combustion behaviour has been possible, yet other properties, mainly but not exclusively physical in nature, do exist for which the reverse is the case. Properties falling in the latter category are those which show relatively little variation as between hydrocarbon types or as between isomers, and include carbon/hydrogen ratio, density, vapour pressure, viscosity, and inflammability limits. The influence of these properties on the combustion process is discussed in detail under the two main heads, ( a) fuel injection and stabilization of flame, and ( b) the burning of the droplets after ignition, and the nature of the exhaust products. A number of new and interesting generalizations emerge from this discussion, and are presented in graphical form. Though no hard and fast conclusions may be drawn, the author indicates that the main fuel characteristics affecting gas turbine operation are viscosity, initial and final volatility, elementary analysis of the organic constituents and physical characteristics of the ash.

Development and Integration of the Dual Fuel Combustion System for the MGT Gas Turbine Family

2021 ◽  
Author(s):  
Bernhard Ćosić ◽  
Frank Reiss ◽  
Marc Blümer ◽  
Christian Frekers ◽  
Franklin Genin ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Distribution System ◽  
Gas Turbines ◽  
Liquid Fuel ◽  
Fuel Injection ◽  
Liquid Fuels ◽  
Dual Fuel ◽  
Gaseous Fuels ◽  
Supply And Distribution ◽  
Industrial Gas Turbines

Abstract Industrial gas turbines like the MGT6000 are often operated as power supply or as mechanical drives. In these applications, liquid fuels like 'Diesel Fuel No.2' can be used either as main fuel or as backup fuel if natural gas is not reliably available. The MAN Gas Turbines (MGT) operate with the Advanced Can Combustion (ACC) system, which is capable of ultra-low NOx emissions for gaseous fuels. This system has been further developed to provide dry dual fuel capability. In the present paper, we describe the design and detailed experimental validation process of the liquid fuel injection, and its integration into the gas turbine package. A central lance with an integrated two-stage nozzle is employed as a liquid pilot stage, enabling ignition and start-up of the engine on liquid fuel only. The pilot stage is continuously operated, whereas the bulk of the liquid fuel is injected through the premixed combustor stage. The premixed stage comprises a set of four decentralized nozzles based on fluidic oscillator atomizers, wherein atomization of the liquid fuel is achieved through self-induced oscillations. We present results illustrating the spray, hydrodynamic, and emission performance of the injectors. Extensive testing of the burner at atmospheric and full load high-pressure conditions has been performed, before verification within full engine tests. We show the design of the fuel supply and distribution system. Finally, we discuss the integration of the dual fuel system into the standard gas turbine package of the MGT6000.

The Effect of Water Injection for Emissions Control on Industrial Gas Turbine Combustors

1984 ◽  
Author(s):  
R. J. Antos ◽  
W. C. Emmerling
Keyword(s):  
Gas Turbines ◽  
Mechanical Design ◽  
Water Injection ◽  
Combustion Process ◽  
Liquid Fuels ◽  
Nox Emissions ◽  
Design Features ◽  
Industrial Gas Turbines ◽  
Comprehensive Test ◽  
Industrial Gas Turbine

One common method of reducing the NOx emissions from industrial gas turbines is to inject water into the combustion process. The amount of water injected depends on the emissions rules that apply to a particular unit. Westinghouse W501B industrial gas turbines have been operated at water injection levels required to meet EPA NOx emissions regulations. They also have been operated at higher injection levels required to meet stricter California regulations. Operation at the lower rates of water did not affect combustor inspection and/or repair intervals. Operation on liquid fuels with high rates of water also did not result in premature distress. However, operation on gas fuel at high rates of water did cause premature distress in the combustors. To evaluate this phenomenon, a comprehensive test program was conducted; it demonstrated that the distress is the result of the temperature patterns in the combustor caused by the high rates of water. The test also indicated that there is no significant change in dynamic response levels in the combustor. This paper presents the test results, and the design features selected to substantially improve combustor wall temperature when operating on gas fuels, with the high rates of water injection required to meet California applications. Mechanical design features that improve combustor resistance to water injection-induced thermal gradients also are presented.

Investigation of Reverse Flow Slinger Combustor with Jet A-1 and Methanol

2021 ◽  
Author(s):  
Abhishek Dubey ◽  
Pooja Nema ◽  
Abhijit Kushari
Keyword(s):  
Fuel Injection ◽  
Reverse Flow ◽  
Lightweight Design ◽  
Injection Pressure ◽  
Combustion Efficiency ◽  
Flame Stabilization ◽  
Liquid Fuels ◽  
Flame Stability ◽  
Lean Blowout ◽  
Lean Fuel

Abstract This paper describes experimental investigation of a Reverse Flow Slinger (RFS) combustor that has been developed in order to attain high flame stability and low emissions in gas turbine engines. The combustor employs centrifugal fuel injection through a rotary atomizer and performs flame stabilization at the stagnation zone generated by reverse flow configuration. The design facilitates entrainment of hot product gases and internal preheating of the inlet air which enhances flame stability and permits stable lean operation for low NOx. Moreover, the use of rotary atomizer eliminates the need for high injection pressure resulting in a compact and lightweight design. Atmospheric pressure combustion was performed with liquid fuels, Jet A-1 and Methanol at ultra-lean fuel air ratios (FAR) with thermal intensity of 28 - 50 MW/m3atm. Combustor performance was evaluated by analyzing the lean blowout, emissions and combustion efficiency. Test results showed high flame stability of combustor and a very low lean blowout corresponding to global equivalence ratio of around 0.1 was obtained. Sustained and stable combustion at low heat release was attained and NOx emissions as low as of 0.4 g/Kg and 0.1 g/Kg were obtained with Jet A-1 and Methanol respectively. Combustion efficiency of 55% and 90% was obtained in operation with Jet A-1 and Methanol. Performance of the combustor was significantly better with Methanol in terms of emissions and efficiency.

Flame Holding in the Premixing Zone of a Gas Turbine Model Combustor After Forced Ignition of H2-NG-Air-Mixtures

2016 ◽  
Author(s):  
Matthias Utschick ◽  
Thomas Sattelmayer
Keyword(s):  
Gas Turbine ◽  
Atmospheric Pressure ◽  
Gas Turbines ◽  
Fuel Injection ◽  
Air Flow ◽  
Fuel Injector ◽  
Safe Operation ◽  
Trailing Edge ◽  
Damage And Failure ◽  
Turbine Model

Flashback and self-ignition in the premixing zone of typical gas turbine swirl combustors in lean premixed operation are immanent risks and can lead to damage and failure of components. Thus, steady combustion in the premixing zone must be avoided under all circumstances. This study experimentally investigates the flame holding propensity of fuel injectors in the swirler of a gas turbine model combustor with premixing of H2-NG-air-mixtures under atmospheric pressure and proposes a model to predict the limit for safe operation. The A2EV swirler concept exhibits a hollow, thick walled conical structure with four tangential slots. Four fuel injector geometries were tested. One of them injects the fuel orthogonal to the air flow in the slots (jet-in-crossflow-injector, JICI). Three injector types introduce the fuel almost isokinetic to the air flow at the trailing edge of the swirler slots (trailing edge injector, TEI). A cylindrical duct and a window in the swirler made of quartz glass allow the application of optical diagnostics (OH* chemiluminescence and Planar Laser Induced Fluorescence of the OH radical (OH-PLIF)) inside the swirler. The fuel-air-mixture was ignited with a focused single laser pulse during steady operation. The position of ignition was located inside the swirler in proximity to a fuel injection hole. If the flame was washed out of the premixing zone not later than four seconds after the ignition the operation point was defined as safe. Operation points were investigated at three air mass flows, three air ratios, two air preheat temperatures (573 K, 673 K) and 40 to 100 percent per volume hydrogen in the fuel composed of hydrogen and natural gas. The determined safety limit for atmospheric pressure yields a similarity rule based on a critical Damköhler number. Application of the proposed rule at conditions typical for gas turbines leads to these safety limits for the A2EV burner: With the TEIs the swirler can safely operate with up to 80 percent per volume hydrogen content in the fuel at an air ratio of two. With the JIC injector safe operation at stoichiometric conditions and 95 percent per volume hydrogen is possible.

CFD Analysis of Turbec T100 Combustor at Part Load by Varying Fuels

2015 ◽  
Author(s):  
Raffaela Calabria ◽  
Fabio Chiariello ◽  
Patrizio Massoli ◽  
Fabrizio Reale
Keyword(s):  
Natural Gas ◽  
Gas Turbines ◽  
Combustion Process ◽  
Calorific Value ◽  
Operating Conditions ◽  
Liquid Fuels ◽  
Cfd Analysis ◽  
Part Load ◽  
Gaseous Fuels ◽  
Wide Range

In recent years an increasing interest is focused on the study of micro gas turbines (MGT) behavior at part load by varying fuel, in order to determine their versatility. The interest in using MGT is related to the possibility of feeding with a wide range of fuels and to realize efficient cogenerative cycles by recovering heat from exhaust gases at higher temperatures. In this context, the studies on micro gas turbines are focused on the analysis of the machine versatility and flexibility, when operating conditions and fuels are significantly varied. In line of principle, in case of gaseous fuels with similar Wobbe Index no modifications to the combustion chamber should be required. The adoption of fuels whose properties differ greatly from those of design can require relevant modifications of the combustor, besides the proper adaptation of the feeding system. Thus, at low loads or low calorific value fuels, the combustor becomes a critical component of the entire MGT, as regards stability and emissions of the combustion process. Focus of the paper is a 3D CFD analysis of the combustor behavior of a Turbec T100P fueled at different loads and fuels. Differences between combustors designed for natural gas and liquid fuels are also highlighted. In case of natural gas, inlet combustor temperature and pressure were taken from experimental data; in case of different fuels, such data were inferred by using a thermodynamic model which takes into account rotating components behavior through operating maps of compressor and turbine. Specific aim of the work is to underline potentialities and critical issues of the combustor under study in case of adoption of fuels far from the design one and to suggest possible solutions.

Evaluation of Combustion and Emissions Using Biodiesel and Blends With Kerosene in a Low NOx Gas Turbine Combustor

2010 ◽  
Author(s):  
Hu Li ◽  
Mohamed Altaher ◽  
Gordon E. Andrews
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Equivalence Ratio ◽  
Fuel Injection ◽  
Waste Cooking Oil ◽  
Industrial Applications ◽  
Liquid Fuels ◽  
Gaseous Emissions ◽  
Gas Turbine Combustor ◽  
Industrial Gas Turbines

Biofuels offer reduced CO2 emissions for both industrial and aero gas turbines. Industrial applications are more practical due to low temperature waxing problems at altitude. Any use of biofuels in industrial gas turbines must also achieve low NOx and this paper investigates the use of biofuels in a low NOx radial swirler, as used in some industrial low NOx gas turbines. A waste cooking oil derived methyl ester biodiesel (WME) has been tested on a radial swirler industrial low NOx gas turbine combustor under atmospheric pressure and 600K. The pure WME and its blends with kerosene, B20 and B50 (WME:kerosene = 20:80 and 50:50 respectively), and pure kerosene were tested for gaseous emissions and lean extinction as a function of equivalence ratio. The co-firing with natural gas (NG) was tested for kerosene/biofuel blends B20 and B50. The central fuel injection was used for liquid fuels and wall injection was used for NG. The experiments were carried out at a reference Mach number of 0.017. The inlet air to the combustor was heated to 600K. The results show that B20 produced similar NOx at an equivalence ratio of ∼0.5 and a significant low NOx when the equivalence ratio was increased comparing with kerosene. B50 and B100 produced higher NOx compared to kerosene, which indicates deteriorated mixing due to the poor volatility of the biofuel component. The biodiesel lower hydrocarbon and CO emissions than kerosene in the lean combustion range. The lean extinction limit was lower for B50 and B100 than kerosene. It is demonstrated that B20 has the lowest overall emissions. The co-firing with NG using B20 and B50 significantly reduced NOx and CO emissions.

Damping of Combustion Instabilities Through Pseudo-Active Control

2018 ◽  
Author(s):  
Jesús Oliva ◽  
Ennio Luciano ◽  
Javier Ballester
Keyword(s):  
Combustion Chamber ◽  
Active Control ◽  
Gas Turbines ◽  
Fuel Injection ◽  
Pressure Oscillation ◽  
Practical Reasons ◽  
Fuel Injector ◽  
Secondary Fuel ◽  
Pilot Fuel ◽  
Instability Control

Active instability control techniques have demonstrated very good capabilities to correct combustion oscillations but, due to high costs and other practical reasons, have not achieved the success expected in gas turbines engines. A different approach, named here as ‘pseudo-active instability control’, has been explored and the first results are presented in this work. In this case, the flow of non-premixed pilot fuel is modulated by passive methods: the pressure oscillation in the combustion chamber induces a velocity fluctuation at the secondary fuel injector. In principle, damping of the instability may be achieved if the heat release oscillations due to the secondary fuel are out of phase with those of the main flame. This work reports a first exploration of this strategy, aimed mainly at performing a proof of the concept. An experimental study has been carried out in a laboratory premixed combustor with pilot fuel injection. The relationship between the fluctuations of pressure in the combustion chamber and those of velocity at the injector was studied both experimentally (hot wire anemometry) and theoretically (1-D acoustic model of the injection line). Combustion tests in limit cycle conditions demonstrated that modifications in the geometry of the secondary injection affected the pressure fluctuations inside the combustion chamber. Depending on the geometry (and, hence, acoustic impedance), the instability was enhanced or damped. This demonstrates that the proposed ‘pseudo-active control’ can produce similar effects (at least, qualitatively) to those of active control, but only using passive means, as initially postulated.

Characteristics of Combustion Processes in a Stagnation Point Reverse Flow Combustor

2006 ◽  
Author(s):  
M. K. Bobba ◽  
P. Gopalakrishnan ◽  
J. M. Seitzman ◽  
B. T. Zinn
Keyword(s):  
Stagnation Point ◽  
Gas Turbines ◽  
Equivalence Ratio ◽  
Reverse Flow ◽  
Laser Sheet ◽  
Flame Structure ◽  
Stable Operation ◽  
Oh Radicals ◽  
Combustion Processes ◽  
Hot Products

The performance of dry, low NOx gas turbines, which employ lean premixed (or partially premixed) combustors, is often limited by static and dynamic combustor stability, power density limitations and expensive premixing hardware. To overcome these issues, a novel design, referred to as the Stagnation Point Reverse Flow (SPRF) combustor, has recently been developed. Various optical diagnostic techniques are employed here to elucidate the combustion processes in this novel combustor. These include simultaneous planar laser-induced fluorescence (PLIF) imaging of OH radicals and chemiluminescence imaging, and separate experiments with particle image velocimetry and elastic laser sheet scattering from liquid particles seeded into the fuel. The SPRF combustor achieves internal exhaust gas recirculation and efficient mixing, which eliminates local peaks in temperature. This results in low NOx emissions, limited by flame zone (prompt) production, for both premixed and non-premixed modes of operation. The flame is anchored in a region of reduced velocity and high turbulent intensities, which promotes mixing of hot products into the reactants, thus enabling stable operation of the combustor even at very lean equivalence ratios. Also, the flame structure and flow characteristics were found to remain invariant at high loadings, i.e., mass flow rates. Combustion in the non-premixed mode of operation is found to be similar to the premixed case, with the OH PLIF measurements indicating that nonpremixed flame burns at an equivalence ratio that is close to the overall combustor equivalence ratio. Similarities in emission levels between premixed and non-premixed modes are thus attributable to efficient fuel-air mixing in the nonpremixed mode, and entrainment of hot products into the reactant stream before burning occurs.

Flow and Spray Characteristics of a Lean Fuel Injection Module With Radial Swirlers

2000 ◽  
Author(s):  
Woo Seok Seol ◽  
Yeoung Min Han ◽  
Dae Sung Lee
Keyword(s):  
Fuel Injection ◽  
Reverse Flow ◽  
Jet Fuel ◽  
Fuel Injector ◽  
Flow Zone ◽  
Mixing Rate ◽  
Spray Characteristics ◽  
Injection Point ◽  
Size Number ◽  
Lean Fuel

Lean fuel modules are sometimes employed to reduce NOx emissions in aero-engine combustors. With a lean fuel module whose AFR is larger than the stoichiometric AFR, the bulk AFR remains larger than the stoichiometric AFR throughout the combustor, and hence the peak NOx producing regime can be avoided. In addition, by introducing a large amount of air at the fuel injection point and increasing the mixing rate, the existing time of local stoichiometric pockets can be reduced. In the present study, flow and spray characteristics of a 21AFR lean fuel module, which consists of a pressure jet fuel injector and radial air swirlers, are measured by an adaptive Phase/Doppler technique. Gas phase velocity field, and distributions of droplet size, number density, and liquid phase volume flux are presented for co-swirl and counter-swirl lean modules. The present study reveals that a strong reverse flow zone is formed by the lean fuel module with radial swirlers. The shape of the reverse flow zone and the reverse flow velocity depend on the swirl direction significantly. The lean fuel module with radial swirlers provides effective atomization, and the SMD distribution near the module exit is quite uniform. The swirl direction has significant effects on the spray characteristics, too.

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