Influence of Carrier Air Preheating on Autoignition of Inline-Injected Hydrogen-Nitrogen Mixtures in Vitiated Air of High Temperature

2017 ◽  
Author(s):  
Christoph A. Schmalhofer ◽  
Peter Griebel ◽  
Manfred Aigner
Keyword(s):  
High Temperature ◽  
Gas Turbine ◽  
Gas Turbines ◽  
High Speed ◽  
Spatial Development ◽  
Design Guidelines ◽  
Operating Conditions ◽  
High Speed Imaging ◽  
Temporal And Spatial ◽  
Fuel Mixtures

Gas turbines will play a significant role in future power generation systems because they provide peak capacity due to their fast start-up capability and high operational flexibility. However, in order to meet the COP 21 goals, de-carbonization of as turbine fuels is required. Compared to natural gas operation, autoignition and flashback risks in gas turbines operated on hydrogen-rich fuels are higher which has to be taken into account for a proper gas turbine design. From investigations of these phenomena at relevant operating conditions with appropriate measurement techniques, e.g. high-speed imaging, the understanding of the non-stationary processes occurring during autoignition can be improved and design guidelines for a safe and reliable gas turbine operation can be derived. The present study investigates the influences of elevated carrier-air preheating temperatures and hydrogen fuel volume fractions on autoignition at hot gas temperatures higher than 1100 K and pressures of 15 bar. An in-line co-flow injector is used to inject the hydrogen-nitrogen fuel mixtures. The formation, temporal and spatial development of autoignition kernels at high-temperature vitiated air conditions, e.g. relevant to reheat combustor operation, are studied. The experiments were conducted in an optically accessible mixing section of a generic reheat combustor. The hydrogen-nitrogen fuel mixtures of up to 70 vol. % hydrogen are injected in-line into the mixing section along with the carrier-air which was preheated to temperatures between 303 K and 703 K. High-speed imaging was used to detect the autoignition kernels and their temporal and spatial development from luminescence signals. Particle Image Velocimetry measurements were conducted to obtain the velocity distribution in the mixing section at autoignition conditions. The influences of vitiated air temperatures and carrier preheating temperatures on autoignition and flame stabilisation limits are shown, alongside the spatial distribution of different types of autoignition kernels, developing at different stages of the autoignition process. The development of autoignition kernels could be linked to the shear layer development derived from global experimental conditions.

Auto-Ignition of In-Line Injected Hydrogen/Nitrogen Fuel Mixtures at Reheat Combustor Operating Conditions

2015 ◽  
Author(s):  
Christoph Schmalhofer ◽  
Peter Griebel ◽  
Michael Stöhr ◽  
Manfred Aigner ◽  
Torsten Wind
Keyword(s):  
Gas Turbine ◽  
High Speed ◽  
Design Guidelines ◽  
Operating Conditions ◽  
Fuel Injector ◽  
High Speed Imaging ◽  
Capture Process ◽  
Carrier Medium ◽  
Auto Ignition ◽  
Ignition Limits

De-carbonization of the power generation sector becomes increasingly important in order to achieve the European climate targets. Coal or biomass gasification together with a pre-combustion carbon capture process might be a solution resulting in hydrogen-rich gas turbine (GT) fuels. However, the high reactivity of these fuels poses challenges to the operability of lean premixed gas turbine combustion systems because of a higher auto-ignition and flashback risk. Investigation of these phenomena at GT relevant operating conditions is needed to gain knowledge and to derive design guidelines for a safe and reliable operation. The present investigation focusses on the influence of the fuel injector configuration on auto-ignition and kernel development at reheat combustor relevant operating conditions. Auto-ignition of H2-rich fuels was investigated in the optically accessible mixing section of a generic reheat combustor. Two different geometrical in-line configurations were investigated. In the premixed configuration, the fuel mixture (H2 / N2) and the carrier medium nitrogen (N2) were homogeneously premixed before injection, whereas in the co-flow configuration the fuel (H2 / N2) jet was embedded in a carrier medium (N2 or air) co-flow. High-speed imaging was used to detect auto-ignition and to record the temporal and spatial development of auto-ignition kernels in the mixing section. A high temperature sensitivity of the auto-ignition limits were observed for all configurations investigated. The lowest auto-ignition limits are measured for the premixed in-line injection. Significantly higher auto-ignition limits were determined in the co-flow in-line configuration. The analysis of auto-ignition kernels clearly showed the inhibiting influence of fuel dilution for all configurations.

scholarly journals The Influence of Carrier Air Preheating on Autoignition of Inline-Injected Hydrogen–Nitrogen Mixtures in Vitiated Air of High Temperature

2017 ◽  
Vol 140 (3) ◽  
Author(s):  
Christoph A. Schmalhofer ◽  
Peter Griebel ◽  
Manfred Aigner
Keyword(s):  
Hydrogen Content ◽  
Gas Turbines ◽  
High Speed ◽  
Flame Stabilization ◽  
Operating Conditions ◽  
Promoting Effect ◽  
Experimental Conditions ◽  
Lean Premixed Combustion ◽  
Image Velocimetry ◽  
Fuel Mixtures

The use of highly reactive hydrogen-rich fuels in lean premixed combustion systems strongly affects the operability of stationary gas turbines (GT) resulting in higher autoignition and flashback risks. The present study investigates the autoignition behavior and ignition kernel evolution of hydrogen–nitrogen fuel mixtures in an inline co-flow injector configuration at relevant reheat combustor operating conditions. High-speed luminosity and particle image velocimetry (PIV) measurements in an optically accessible reheat combustor are employed. Autoignition and flame stabilization limits strongly depend on temperatures of vitiated air and carrier preheating. Higher hydrogen content significantly promotes the formation and development of different types of autoignition kernels: More autoignition kernels evolve with higher hydrogen content showing the promoting effect of equivalence ratio on local ignition events. Autoignition kernels develop downstream a certain distance from the injector, indicating the influence of ignition delay on kernel development. The development of autoignition kernels is linked to the shear layer development derived from global experimental conditions.

Advancement in Heated Spin Testing Technologies

2013 ◽  
Author(s):  
Hiroaki Endo ◽  
Robert Wetherbee ◽  
Nikhil Kaushal
Keyword(s):  
High Temperature ◽  
Gas Turbine ◽  
Material Properties ◽  
Gas Turbines ◽  
Multiple Scales ◽  
Thermal Conditions ◽  
Complex Stress ◽  
Operating Conditions ◽  
Mechanical Cycling ◽  
Testing Techniques

An ever more rapidly accelerating trend toward pursuing more efficient gas turbines pushes the engines to hotter and more arduous operating conditions. This trend drives the need for new materials, coatings and associated modeling and testing techniques required to evaluate new component design in high temperature environments and complex stress conditions. This paper will present the recent advances in spin testing techniques that are capable of creating complex stress and thermal conditions, which more closely represent “engine like” conditions. The data from the tests will also become essential references that support the effort in Integrated Computational Materials Engineering (ICME) and in the advances in rotor design and lifing analysis models. Future innovation in aerospace products is critically depended on simultaneous engineering of material properties, product design, and manufacturing processes. ICME is an emerging discipline with an approach to design products, the materials that comprise them, and their associated materials processing methods by linking materials models at multiple scales (Structural, Macro, Meso, Micro, Nano, etc). The focus of the ICME is on the materials; understanding how processes produce material structures, how those structures give rise to material properties, and how to select and/or engineer materials for a given application [34]. The use of advanced high temperature spin testing technologies, including thermal gradient and thermo-mechanical cycling capabilities, combined with the innovative use of modern sensors and instrumentation methods, enables the examination of gas turbine discs and blades under the thermal and the mechanical loads that are more relevant to the conditions of the problematic damages occurring in modern gas turbine engines.

Fuel Influence on Targeted Gas Turbine Combustion Properties: Part I — Detailed Diagnostics

2014 ◽  
Author(s):  
Thomas Mosbach ◽  
Victor Burger ◽  
Barani Gunasekaran
Keyword(s):  
Gas Turbine ◽  
High Speed ◽  
Leading Edge ◽  
Operating Conditions ◽  
Optical Measurements ◽  
Test Facility ◽  
Research Centre ◽  
High Speed Imaging ◽  
Combustion Properties ◽  
First Results

The threshold combustion performance of different fuel formulations under simulated altitude relight conditions were investigated in the altitude relight test facility located at the Rolls-Royce plc. Strategic Research Centre in Derby, UK. The combustor employed was a twin-sector representation of an RQL gas turbine combustor. Eight fuels including conventional crude-derived Jet A-1 kerosene, synthetic paraffinic kerosenes (SPKs), linear paraffinic solvents, aromatic solvents and pure compounds were tested. The combustor was operated at sub-atmospheric air pressure of 41 kPa and air temperature of 265 K. The temperature of all fuels was regulated to 288 K. The combustor operating conditions corresponded to a low stratospheric flight altitude near 9 kilometres. The experimental work at the Rolls-Royce (RR) test-rig consisted of classical relight envelope ignition and extinction tests, and ancillary optical measurements: Simultaneous high-speed imaging of the OH* chemiluminescence and of the soot luminosity was used to visualize both the transient combustion phenomena and the combustion behaviour of the steady burning flames. Flame luminosity spectra were also simultaneously recorded with a spectrometer to obtain information about the different combustion intermediates and about the thermal soot radiation curve. This paper presents first results from the analysis of the weak extinction measurements. Further detailed test fuel results are the subject of a separate complementary paper [1]. It was found in general that the determined weak extinction parameters were not strongly dependent on the fuels investigated, however at the leading edge of the OH* chemiluminescence intensity development in the pre-flame region fuel-related differences were observed.

Development and Testing of Harsh Environment, Wireless Sensor Systems for Industrial Gas Turbines

2009 ◽  
Author(s):  
David Mitchell ◽  
Anand Kulkarni ◽  
Alex Lostetter ◽  
Marcelo Schupbach ◽  
John Fraley ◽  
...  
Keyword(s):  
High Temperature ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Turbine Blades ◽  
Operating Conditions ◽  
Condition Based Maintenance ◽  
Harsh Environment ◽  
Sensor Systems ◽  
Wireless Telemetry ◽  
Industrial Gas Turbines

The potential for savings provided to worldwide operators of industrial gas turbines, by transitioning from the current standard of interval-based maintenance to condition-based maintenance may be in the hundreds of millions of dollars. In addition, the operational flexibility that may be obtained by knowing the historical and current condition of life-limiting components will enable more efficient use of industrial gas turbine resources, with less risk of unplanned outages as a result of off-parameter operations. To date, it has been impossible to apply true condition-based maintenance to industrial gas turbines because the extremely harsh operating conditions in the heart of a gas turbine preclude using the necessary advanced sensor systems to monitor the machine’s condition continuously. Siemens, Rove Technical Services, and Arkansas Power Electronics International are working together to develop a potentially industry-changing technology to build smart, self-aware engine components that incorporate embedded, harsh-environment-capable sensors and high temperature capable wireless telemetry systems for continuously monitoring component condition in the hot gas path turbine sections. The approach involves embedding sensors on complex shapes, such as turbine blades, embedding wireless telemetry systems in regions with temperatures that preclude the use of conventional silicon-based electronics, and successfully transmitting the sensor information from an environment very hostile to wireless signals. The results presented will include those from advanced, harsh environment sensor and wireless telemetry component development activities. In addition, results from laboratory and high temperature rig and spin testing will be discussed.

Steady Characteristics of High-Speed Micro-Gas Journal Bearings With Different Gaseous Lubricants and Extreme Temperature Difference

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Xueqing Zhang ◽  
Qinghua Chen ◽  
Juanfang Liu
Keyword(s):  
High Temperature ◽  
Temperature Difference ◽  
Gas Turbines ◽  
High Speed ◽  
Load Capacity ◽  
Axial Direction ◽  
Operating Conditions ◽  
Thermal Creep ◽  
Large Temperature ◽  
The Stability

High-speed micro-gas journal bearing is one of the essential components of micro-gas turbines. As for the operating conditions of bearings, the high-speed, high-temperature, ultra-high temperature difference along the axial direction and the species of gaseous lubricants are extremely essential to be taken into account, and the effects of these factors are examined in this paper. The first-order modified Reynolds equation including the thermal creep, which results from the extremely large temperature gradient along the axial direction, is first derived and coupled with the simplified energy equation to investigate the steady hydrodynamic characteristics of the micro-gas bearings. Under the isothermal condition, it is found that CO2 can not only improve the stability of bearings but also generate a relatively higher load capacity by some comparisons. Thus, CO2 is chosen as the lubricant to further explore the influence of thermal creep. As the rotation speed and eccentricity ratio change, the thermal creep hardly has any effect on the gas film pressure. However, the shorter bearing length can augment the thermal creep. Compared with the cases without the thermal creep, the thermal creep could remarkably destroy the stability of gas bearing, but it might slightly enhance the load capacity.

Autoignition Limits of Hydrogen at Relevant Reheat Combustor Operating Conditions

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
J. Fleck ◽  
P. Griebel ◽  
A.M. Steinberg ◽  
M. Stöhr ◽  
M. Aigner ◽  
...  
Keyword(s):  
Flue Gas ◽  
Gas Turbines ◽  
High Speed ◽  
Initial Position ◽  
Operating Conditions ◽  
Dominant Factor ◽  
High Speed Imaging ◽  
Lean Premixed Combustion ◽  
Fuel Jet ◽  
Image Velocimetry

The use of highly reactive fuels in the lean premixed combustion systems employed in stationary gas turbines can lead to many practical problems, such as unwanted autoignition in regions not designed for combustion. In the present study, autoignition characteristics for hydrogen, diluted with up to 30 vol. % nitrogen, were investigated at conditions relevant to reheat combustor operation (p = 15 bar, T >1000 K, hot flue gas, relevant residence times). The experiments were performed in a generic, optically accessible reheat combustor, by applying high-speed imaging and particle image velocimetry. Autoignition limits for different mixing section (temperature, velocity) and fuel jet (N2 dilution) parameters are described. The dominant factor influencing autoignition was the temperature, with an increase of around 2% leading to a reduction of the highest possible H2 concentration without “flame-stabilizing autoignition kernels” of approximately 16 vol. %. Furthermore, the onset and propagation of the ignition kernels were elucidated using the high-speed measurements. It was found that the ability of individual autoignition kernels to develop into stable flames depends on the initial position of the kernel and the corresponding axial velocity at that position. While unwanted autoignition occurred prior to reaching the desired operating point for most investigated conditions, for certain conditions the reheat combustor could be operated stably with up to 80 vol. % H2 in the fuel.

Autoignition Limits of Hydrogen at Relevant Reheat Combustor Operating Conditions

2011 ◽  
Author(s):  
Julia Fleck ◽  
Peter Griebel ◽  
Adam M. Steinberg ◽  
Michael Sto¨hr ◽  
Manfred Aigner ◽  
...  
Keyword(s):  
Flue Gas ◽  
Gas Turbines ◽  
High Speed ◽  
Initial Position ◽  
Operating Conditions ◽  
Dominant Factor ◽  
High Speed Imaging ◽  
Lean Premixed Combustion ◽  
Fuel Jet ◽  
Image Velocimetry

The use of highly reactive fuels in the lean premixed combustion systems employed in stationary gas turbines can lead to many practical problems, such as unwanted autoignition in regions not designed for combustion. In the present study, autoignition characteristics for hydrogen, diluted with up to 30 vol. % nitrogen, were investigated at conditions relevant to reheat combustor operation (p = 15 bar, T > 1000 K, hot flue gas, relevant residence times). The experiments were performed in a generic, optically accessible reheat combustor, by applying high-speed imaging and Particle Image Velocimetry (PIV). Autoignition limits for different mixing section (temperature, velocity) and fuel jet (N2 dilution) parameters are described. The dominant factor influencing autoignition was the temperature, with an increase of around 2% leading to a reduction of the highest possible H2 concentration without “flame-stabilizing autoignition kernels” of approximately 16 vol. %. Furthermore, the onset and propagation of the ignition kernels were elucidated using the high-speed measurements. It was found that the ability of individual autoignition kernels to develop into stable flames depends on the initial position of the kernel and the corresponding axial velocity at that position. While unwanted autoignition occurred prior to reaching the desired operating point for most investigated conditions, for certain conditions the reheat combustor could be operated stably with up to 80 vol. % H2 in the fuel.

A Realistic Method to Establish the Required Gearbox Rating for a Gas Turbine Application

1995 ◽  
Author(s):  
A. K. Rakhit
Keyword(s):  
Gas Turbine ◽  
Air Temperature ◽  
Gas Turbines ◽  
High Speed ◽  
Great Majority ◽  
Operating Conditions ◽  
Successful Operation ◽  
Turbine Performance ◽  
Transmission Equipment ◽  
Turbine Output

A reliable gearbox rating is essential for successful operation of high speed gas turbines. Presently, there is no dependable method to establish such a rating based on actual gas turbine performance under operating conditions. A great majority of manufacturers of this equipment use gas turbine output power at inlet air temperature of −20°F as the basis for this rating, while others assume an arbitrary inlet air temperature profile for turbine operation and use turbine output powers at various temperatures of the profile to derive an average rating for the gearbox. The major drawbacks of these methods are that they do not consider the effects of turbine performance characteristics and also do not include temperature profiles of actual installation sites. Thus, a vast majority of gear transmission equipment used in today’s high speed turbomachinery applications are either under- or over-rated. The procedure, as outlined in this paper, provides a reliable method to rate gearboxes for gas turbine driven equipment.

A Damage Evaluation Model of Turbine Blade for Gas Turbine

2017 ◽  
Vol 139 (9) ◽  
Author(s):  
Dengji Zhou ◽  
Tingting Wei ◽  
Huisheng Zhang ◽  
Shixi Ma ◽  
Shilie Weng
Keyword(s):  
High Temperature ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Evaluation Model ◽  
Operating Conditions ◽  
Damage Analysis ◽  
Damage Evaluation ◽  
Analysis Model ◽  
Estimation Model ◽  
Life Consumption

Current maintenance, having a great impact on the safety, reliability and economics of a gas turbine, becomes the major obstacle for the application of gas turbines in energy field. An effective solution is to process condition based maintenance (CBM) thoroughly for gas turbines. Maintenance of high temperature blade, accounting for the most of the maintenance costs and time, is the crucial section of gas turbine maintenance. The suggested life of high temperature blade by original equipment manufacturer (OEM) is based on several certain operating conditions, which is used for time based maintenance (TBM). Thus, for the requirement of gas turbine CBM, a damage evaluation model is demanded to estimate the life consumption online. A physics-based model is built, consisting of thermodynamic performance simulation model, stress estimation model, thermal estimation model, and interactive damage analysis model. Unmeasured parameters are simulated by the thermodynamic performance simulation model, as the input of the stress estimation model and the thermal estimation model. Due to the ability to analyze online data, this model can be used to calculate online damage and support CBM decision. Then the stress and temperature distribution of blades will become as the input of the creep damage analysis model and the fatigue damage analysis model. The interactive damage of blades will be evaluated based on the creep and fatigue analysis results. To validate this physics-based model, it is used to calculate the lifes of high temperature blade under several certain operating conditions. And the results are compared to the suggestion value of OEM. An application case is designed to evaluate the application effect of this model. The result shows that the relative error of this model is less than 10.4% in selected cases. And it can cut overhaul costs and increase the availability of gas turbines significantly. Finally, a simple application of this model is proposed to show its functions. The physical-based damage evaluation model proposed in this paper is found to be a useful tool to tracing the online life consumption of a high temperature blade, to support the implementation of CBM for gas turbines, and to guarantee the reliability of gas turbines with lowest maintenance costs.

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