Fuel Interchangeability for Lean Premixed Combustion in Gas Turbine Engines

2008 ◽  
Author(s):  
Don Ferguson ◽  
Geo. A. Richard ◽  
Doug Straub
Keyword(s):  
Natural Gas ◽  
Dynamic Response ◽  
Gas Turbine ◽  
Turbine Engines ◽  
Nox Emissions ◽  
Gas Turbine Engines ◽  
Lean Premixed Combustion ◽  
Combustion Dynamics ◽  
Rijke Tube ◽  
Fuel Blends

In response to environmental concerns of NOx emissions, gas turbine manufacturers have developed engines that operate under lean, pre-mixed fuel and air conditions. While this has proven to reduce NOx emissions by lowering peak flame temperatures, it is not without its limitations as engines utilizing this technology are more susceptible to combustion dynamics. Although dependent on a number of mechanisms, changes in fuel composition can alter the dynamic response of a given combustion system. This is of particular interest as increases in demand of domestic natural gas have fueled efforts to utilize alternatives such as coal derived syngas, imported liquefied natural gas and hydrogen or hydrogen augmented fuels. However, prior to changing the fuel supply end-users need to understand how their system will respond. A variety of historical parameters have been utilized to determine fuel interchangeability such as Wobbe and Weaver Indices, however these parameters were never optimized for today’s engines operating under lean pre-mixed combustion. This paper provides a discussion of currently available parameters to describe fuel interchangeability. Through the analysis of the dynamic response of a lab-scale Rijke tube combustor operating on various fuel blends, it is shown that commonly used indices are inadequate for describing combustion specific phenomena.

Active Combustion Control by Fuel Forcing at Non-Coherent Frequencies

2007 ◽  
Author(s):  
Chukwueloka O. Umeh ◽  
Leonardo C. Kammer ◽  
Corneliu Barbu
Keyword(s):  
Gas Turbine ◽  
Pressure Fluctuations ◽  
Open Loop ◽  
Turbine Engines ◽  
Nox Emissions ◽  
Gas Turbine Engines ◽  
Combustion Control ◽  
Combustion Dynamics ◽  
Loop Control ◽  
Active Combustion Control

One impediment to substantially further the reductions in NOx emissions for aviation gas turbine engines is thermal-acoustic instabilities, also referred to as combustion dynamics. Dynamics arise due to the coupling of heat and pressure fluctuations in such systems. Numerous passive and semi-active control schemes, including performance de-rating and fuel staging, have been developed for land-based gas turbine engines. However, many of these schemes are not well suited to aviation engines, as a result of their weight and bulk. Observations of several combustors operating on either gaseous or liquid fuels show that the dominant dynamic frequencies have a special relation to specific non-coherent lower frequencies. Experiments show that combinations of two of these non-coherent frequencies form the dominant tones of the combustor. As part of NASA’s intelligent engines program, active combustion control is used to mitigate dynamics, as the combustor’s bulk fuel-air ratio (FAR) is made leaner in an effort to reduce NOx emissions by about 85% below the Committee on Aviation Environmental Protection (CAEP) 6 limit. In the feedback control scheme suggested in this paper, a small percentage of the overall fuel flow is pulsed at a given non-coherent frequency and with varying amplitude. The effectiveness of the dynamics reduction approach has been demonstrated via preliminary open loop control tests on a liquid-fuelled partially premixed high-pressure combustion test rig at GE Aviation in Evendale, Ohio.

Design Study of an Advanced Concept Simple Gas Turbine for Possible Use in Low Emission Automobiles

1972 ◽  
Author(s):  
H. C. Eatock ◽  
M. D. Stoten
Keyword(s):  
High Pressure ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Pressure Ratio ◽  
Simple Cycle ◽  
Turbine Engines ◽  
Nox Emissions ◽  
Preliminary Design ◽  
Gas Turbine Engines ◽  
High Pressure Ratio

United Aircraft Corporation studied the potential costs of various possible gas turbine engines which might be used to reduce automobile exhaust emissions. As part of that study, United Aircraft of Canada undertook the preliminary design and performance analysis of high-pressure-ratio nonregenerated (simple cycle) gas turbine engines. For the first time, high levels of single-stage component efficiency are available extending from a pressure ratio less than 4 up to 10 or 12 to 1. As a result, the study showed that the simple-cycle engine may provide satisfactory running costs with significantly lower manufacturing costs and NOx emissions than a regenerated engine. In this paper some features of the preliminary design of both single-shaft and a free power turbine version of this engine are examined. The major component technology assumptions, in particular the high pressure ratio centrifugal compressor, employed for performance extrapolation are explained and compared with current technology. The potential low NOx emissions of the simple-cycle gas turbine compared to regenerative or recuperative gas turbines is discussed. Finally, some of the problems which might be encountered in using this totally different power plant for the conventional automobile are identified.

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.

Experimental and Numerical Characterization of Lean Hydrogen Combustion in a Premix Burner Prototype

2011 ◽  
Author(s):  
Iarno Brunetti ◽  
Giovanni Riccio ◽  
Nicola Rossi ◽  
Alessandro Cappelletti ◽  
Lucia Bonelli ◽  
...  
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Hydrogen Content ◽  
Premixed Combustion ◽  
Nox Emissions ◽  
Cfd Model ◽  
Air Velocity ◽  
Lean Premixed Combustion ◽  
Lean Premixed

The use of hydrogen as derived fuel for low emission gas turbine is a crucial issue of clean coal technology power plant based on IGCC (Integrated Gasification Combined Cycle) technology. Control of NOx emissions in gas turbines supplied by natural gas is effectively achieved by lean premixed combustion technology; conversely, its application to NOx emission reduction in high hydrogen content fuels is not a reliable practice yet. Since the hydrogen premixed flame is featured by considerably higher flame speed than natural gas, very high air velocity values are required to prevent flash-back phenomena, with obvious negative repercussions on combustor pressure drop. In this context, the characterization of hydrogen lean premixed combustion via experimental and modeling analysis has a special interest for the development of hydrogen low NOx combustors. This paper describes the experimental and numerical investigations carried-out on a lean premixed burner prototype supplied by methane-hydrogen mixture with an hydrogen content up to 100%. The experimental activities were performed with the aim to collect practical data about the effect of the hydrogen content in the fuel on combustion parameters as: air velocity flash-back limit, heat release distribution, NOx emissions. This preliminary data set represents the starting point for a more ambitious project which foresees the upgrading of the hydrogen gas turbine combustor installed by ENEL in Fusina (Italy). The same data will be used also for building a computational fluid dynamic (CFD) model usable for assisting the design of the upgraded combustor. Starting from an existing heavy-duty gas turbine burner, a burner prototype was designed by means of CFD modeling and hot-wire measurements. The geometry of the new premixer was defined in order to control turbulent phenomena that could promote the flame moving-back into the duct, to increase the premixer outlet velocity and to produce a stable central recirculation zone in front of the burner. The burner prototype was then investigated during a test campaign performed at the ENEL’s TAO test facility in Livorno (Italy) which allows combustion test at atmospheric pressure with application of optical diagnostic techniques. In-flame temperature profiles, pollutant emissions and OH* chemiluminescence were measured over a wide range of the main operating parameters for three fuels with different hydrogen content (0, 75% and 100% by vol.). Flame control on burner prototype fired by pure hydrogen was achieved by managing both the premixing degree and the air discharge velocity, affecting the NOx emissions and combustor pressure losses respectively. A CFD model of the above-mentioned combustion test rig was developed with the aim to validate the model prediction capabilities and to help the experimental data analysis. Detailed simulations, performed by a CFD 3-D RANS commercial code, were focused on air/fuel mixing process, temperature field, flame position and NOx emission estimation.

Chemical Kinetic Modeling of Ignition and Emissions From Natural Gas and LNG Fueled Gas Turbines

2012 ◽  
Author(s):  
P. Gokulakrishnan ◽  
C. C. Fuller ◽  
R. G. Joklik ◽  
M. S. Klassen
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Chemical Kinetic ◽  
Higher Order ◽  
Premixed Combustion ◽  
Nox Emissions ◽  
Lean Premixed Combustion ◽  
Lean Premixed ◽  
Combustion Systems

Single digit NOx emission targets as part of gas turbine design criteria require highly accurate modeling of the various NOx formation pathways. The concept of lean, premixed combustion is adopted in various gas turbine combustor designs, which achieves lower NOx levels by primarily lowering the flame temperature. At these conditions, the post-flame thermal-NOx pathway contribution to the total NOx can be relatively small compared to that from the prompt-NOx and the N2O-route, which are enhanced by the super-equilibrium radical pathway at the flame front. In addition, new sources of natural gas fuel (e.g., imported LNG) with widely varying chemical compositions including higher order hydrocarbon components, impact flame stability, lean blow-out limits and emissions in existing lean premixed combustion systems. Also, the presence of higher order hydrocarbons can increase the risk of flashback induced by autoignition in the premixing section of the combustor. In this work a detailed chemical kinetic model was developed for natural gas fuels that consist of CH4, C2H6, C3H8, nC4H10, iC4H10, and small amounts of nC5H12, iC5H12 and nC6H14 in order to predict ignition behavior at typical gas turbine premixing conditions and to predict CO and NOx emissions at lean premixed combustion conditions. The model was validated for different NOx-pathways using low and high pressure laminar premixed flame data. The model was also extended to include a vitiated kinetic scheme to account for the influence of exhaust gas recirculation on fuel oxidation. The model was employed in a chemical reactor network to simulate a laboratory scale lean premixed combustion system to predict CO and NOx. The current kinetic mechanism demonstrates good predictive capability for NOx emissions at lower temperatures typical of practical lean premixed combustion systems.

Lowest emission sustainable aviation biofuels as the potential replacement for the Jet-A fuels

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Anderson A. ◽  
Karthikeyan A. ◽  
Ramesh Kumar C. ◽  
Ramachandran S. ◽  
Praveenkumar T.R.
Keyword(s):  
Gas Turbine ◽  
Fossil Fuels ◽  
Gas Turbine Engine ◽  
Turbine Engines ◽  
Emission Characteristics ◽  
Gas Turbine Engines ◽  
Content Type ◽  
Turbine Engine ◽  
Micro Gas Turbine ◽  
Fuel Blends

Purpose The purpose of this study is to predict the performance and emission characteristics of micro gas turbine engines powered by alternate fuels. The micro gas turbine engine performance, combustion and emission characteristics are analyzed for the jet fuel with different additives. Design/methodology/approach The experimental investigation was carried out with Jet A-1 fuel on the gas turbine engines at different load conditions. The primary blends of the Jet A-1 fuels are from canola and solid waste pyrolysis oil. Then the ultrasonication of highly concentrated multiwall carbon nanotubes is carried with the primary blends of canola (Jet-A fuel 70%, canola 20% and 10% ethanol) and P20E (Jet-A 70% fuel, 20% PO and 10% ethanol). Findings The consumption of the fuel is appreciable with the blends at a very high static thrust. The 39% reduction in thrust specific fuel consumption associated with a 32% enhance in static thrust with P20E blend among different fuel blends. Moreover, due to the increase in ethanol concentration in the blends PO20E and C20E lead to a 22% rise in thermal efficiency and a 9% increase in higher oxygen content is observed. Practical implications The gas turbine engine emits very low emission of gases such as CO, CO2 and NOx by using the fuel blends, which typically reduces the fossil fuel usage limits with reduced pollutants. Originality/value The emission of the gas turbine engines is further optimized with the addition of hydrogen in Jet-A fuel. That is leading to high specific fuel exergy and owing to the lower carbon content in the hydrogen fuel when compared with that of the fossil fuels used in gas turbine engines. Therefore, the usage of hydrogen with nanofluids was so promising based on the results obtained for replacing fossil fuels.

Combustor Design Trends for Aircraft Gas Turbine Engines

1996 ◽  
Author(s):  
G. J. Sturgess
Keyword(s):  
Gas Turbine ◽  
Considerable Importance ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Enabling Technology ◽  
Commercial Aircraft ◽  
Combustion Dynamics ◽  
Performance Trends ◽  
Air Mixing

Advanced performance trends are surveyed for possible future gas turbine engines to power several classes of military and commercial aircraft. The resulting combustor trends are enumerated. Examples of enabling technology are given. Combustion considerations are discussed, and many commonalities between applications are discovered; fuel/air mixing and combustion dynamics emerge as topics of considerable importance.

The Use of Gaseous Fuels on Aero-Derivative Gas Turbine Engines

1991 ◽  
Author(s):  
Philippe Mathieu ◽  
Pericles Pilidis
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Gas Generator ◽  
Turbine Engine ◽  
Gaseous Fuels ◽  
Flow Balance ◽  
Power Turbine ◽  
Gas Fuel

In this paper, the use of various gaseous fuels in aero-derivative gas turbine engines is analysed. The gases investigated are natural gas and three coal synthetic gases of calorific values which are significantly lower than that of natural gas. The analysis is carried out employing natural gas fuel as a yardstick for comparison. Due to the lower calorific values of synthetic gases, the mass flow balance between compressors and turbines is altered. This in turn affects the matching of the components and the overall performance of a gas turbine engine. The engines examined are a single spool gas generator with a free power turbine and the double engine described in a previous paper. The main conclusion drawn from this analysis is that, for a given power output, the use of synthetic gases will result in an erosion of surge margins and in a reduction of the overall efficiency of the power plant.

Validation of a New Turbulent Flame Speed Facility for the Study of Gas Turbine Fuel Blends at Elevated Pressure

2019 ◽  
Author(s):  
Anibal Morones ◽  
Mattias A. Turner ◽  
Victor León ◽  
Kyle Ruehle ◽  
Eric L. Petersen
Keyword(s):  
Gas Turbine ◽  
High Speed ◽  
Turbulent Flame ◽  
Elevated Pressure ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Turbulent Flame Speed ◽  
Fuel Blends ◽  
New Apparatus ◽  
Fundamental Insight

Abstract Turbulent combustion is a very active and challenging research topic of direct interest to the design and operation of gas turbine engines. A spherically expanding flame immersed in a turbulent field is one way to gain fundamental insight on the effect of turbulence on combustion. This kind of experiment is often conducted inside a fan-stirred flame bomb, preferably at conditions of high pressure, high temperature, and intense turbulence. A new fan-stirred flame bomb was designed and built to provide a device for conducting fundamental turbulent flame measurements at conditions of interest to gas turbine engines. A literature review on existing systems was used as guidance in the design of the turbulence-generation elements in the present rig. A few options of impellers were explored. The flow field produced by the chosen impeller was measured with Laser Doppler Velocimetry (LDV). A detailed exposition of the vessel engineering and construction are presented, including current activities that will extend the use of the facility for heated experiments up to at least 400 K. Before turbulent experiments were attempted, a validation of the rig accuracy and pressure worthiness was made. Finally, a demonstration of the new apparatus was made by testing a lean mixture of syngas. The experiment matrix using hydrogen and H2/CO mixtures included three levels of pressure (1, 5, and, 10 bar) and three levels of turbulence fluctuation rms (1.4, 2.8, and 5.5 m/s). Data based on the high-speed schlieren diagnostic are presented.

Development of a Fuel Air Premixer for Aero-Derivative Dry Low Emissions Combustors

1994 ◽  
Author(s):  
Narendra D. Joshi ◽  
Michael J. Epstein ◽  
Susan Durlak ◽  
Steven Marakovits ◽  
Paul E. Sabla
Keyword(s):  
Gas Turbine ◽  
Operating Conditions ◽  
Experimental Program ◽  
Design Parameters ◽  
Turbine Engines ◽  
Nox Emissions ◽  
Gas Turbine Engines ◽  
Single Digit ◽  
Test Conditions ◽  
Industrial Gas Turbine

An experimental program was conducted to develop premixer concepts for use in GE’s aero-derivative Marine and Industrial gas turbine engines such as the LM 1600, 2500 and 6000. These engines operate typically at pressure ratios up to 30:1. Extensive tests in 1 and 2 cup test combustors were carried out to evaluate the Double Annular Counter-Rotating Swirler (DACRS) premixers at test conditions representative of the above mentioned engines. These tests also help establish combustor design parameters. Single digit NOx emissions were measured at engine operating conditions with the DACRS II and III premixers. Premixer interactions and their effects on Lean Blow Out were also studied.

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