Development of Low Emission Gas Turbine Combustors

2015 ◽  
Author(s):  
Seung-chai Jung ◽  
Siwon Yang ◽  
Shaun Kim ◽  
Ik Soo Kim ◽  
Chul-ju Ahn ◽  
...  
Keyword(s):  
Gas Turbines ◽  
Flow Characteristics ◽  
Flame Stability ◽  
Fuel Distribution ◽  
Eddy Simulation ◽  
Piv Measurement ◽  
Planar Laser ◽  
Air Mixing ◽  
Industrial Gas Turbines ◽  
Combustion Tests

Due to increasing environmental concerns, clean technology has become a key feature in industrial gas turbines. Swirler design is directly associated with the combustion performance for its roles in fuel distribution and flame stability. In this study, the development process of three new conceptual swirlers from Samsung Techwin is presented. Each swirler has unique features to enhance fuel-to-air mixing; Swirler 1 uses tangential air-bypass, Swirler 2 minimizes pressure loss using impeller-like design, and Swirler 3 has combined flow characteristics of axial and radial swirlers. Using extensive computational fluid dynamics (CFD) analysis, lead time and cost in manufacturing the prototypes were significantly reduced. The numerical methods were verified with a lab-scale combustion test; particle image velocimetry (PIV) measurement of cold flow, direct flame images, and OH planar laser induced fluorescence (PLIF) images were compared with result of large-eddy simulation (LES), and they showed good agreement. After design optimization using CFD, full-scale combustion tests were performed for all three swirlers. Flame from each swirler was visualized using a cylindrical quartz liner; direct images and OH chemiluminescence images of flames were obtained. Flame stability and blow-off limit at various air load were examined by gradually lowering the equivalence ratio. NOx and CO concentration were measured at the exhaust. All three swirlers satisfied low NOx and CO levels at the design conditions. The performance maps bounded by the NOx and CO limits and blow-off limit were obtained for all swirlers. Further efforts to maximize the combustors performance will be made.

A Viscoplastic Modeling Approach for MCrAlY Protective Coatings for Gas Turbine Applications

2009 ◽  
Vol 131 (6) ◽  
Author(s):  
Roland Mücke
Keyword(s):  
Gas Turbines ◽  
Protective Coatings ◽  
Thermal Strain ◽  
Flow Characteristics ◽  
Strain Range ◽  
Substrate Material ◽  
Full Scale ◽  
Viscoplastic Material ◽  
Modeling Approach ◽  
Industrial Gas Turbines

MCrAlY coatings are applied in industrial gas turbines and aircraft engines to protect surfaces of hot gas exposed components from oxidation and corrosion at elevated temperature. Apart from oxidation resistance, coatings have to withstand cracking caused by cyclic deformation since coating cracks might propagate into the substrate material and thus limit the lifetime of the parts. In this context, the prediction of the coating maximum stress and the strain range during cyclic loading is important for the lifetime analysis of coated components. Analyzing the state of stress in the coating requires the application of viscoplastic material models. A coupled full-scale cyclic analysis of substrate and coating, however, is very expensive because of the different flow characteristics of both materials. Therefore, this paper proposes an uncoupled modeling approach, which consists of a full-scale cyclic analysis of the component without coating and a fast postprocessing procedure based on a node-by-node integration of the coating constitutive model. This paper presents different aspects of the coating viscoplastic behavior and their computational modeling. The uncoupled analysis is explained in detail and a validation of the procedure is addressed. Finally, the application of the uncoupled modeling approach to a coated turbine blade exposed to a complex engine start-up and shut-down procedure is shown. Throughout the paper bold symbols denote tensors and vectors, e.g., σ stands for the stress tensor with the components σij. The superscripts (.)S and (.)C symbolize the substrate and the coating, respectively, e.g., εthS stands for the tensor of substrate thermal strain. Further symbols are explained in the text.

Experimental Investigation of Performance of an Air Blast Atomizer by Planar Laser Sheet Imaging Technique

2013 ◽  
Author(s):  
Cunxi Liu ◽  
Fuqiang Liu ◽  
Yanhui Mao ◽  
Yong Mu ◽  
Gang Xu
Keyword(s):  
Swirling Flow ◽  
Laser Sheet ◽  
Pollutant Emissions ◽  
Space Distribution ◽  
Imaging Method ◽  
Spray Cone ◽  
Air Blast ◽  
Fuel Distribution ◽  
Planar Laser ◽  
Air Mixing

It is widely recognized that the fuel/air mixing process is a critical factor in improving combustion efficiency and in minimizing pollutants such as NOx. Enhancement of fuel/air mixing can lead to lower pollutant emissions and greater efficiency. However, swirling flows in lean combustors play the role of fuel/air mixing and flame stability. The complex fluid dynamic phenomena encountered in swirling two-phase flow contribute to the difficulty in complete understanding the different processes occurring in combustors. Fortunately, Optical and laser-based visualization techniques available in our lab are important non-intrusive tools for visualizing flow process, especially for fuel injection and fuel/air mixing. To provide for a better understanding of effects of counter-rotating flow on droplets in atomization process, this study is a detailed characterization of the spray generated by an airblast atomizer by planar laser sheet imaging method. Optical facility for spray diagnostics with fuel Planar Laser Induced Fluorescence (fuel-PLIF) method for fuel distribution, and Particle Image Velocity (PIV) method for velocity of droplets, is used to evaluate the performance of an air-blast atomizer. The results show that the performance of secondary atomization is influenced by swirling flow and primary atomization simultaneously, the swirling flow exhibits significant influence on the droplet size and space distribution relative to that of primary atomization. The primary swirling air reopens the spray cone generated by pressure-swirl atomizer, and the secondary swirling air affects the fuel distribution by forming the recirculation zone. The results provide critical information for design and development of combustion chamber.

Investigation of Hydrogen Enriched Natural Gas Flames in a SGT-700/800 Burner Using OH PLIF and Chemiluminescence Imaging

2014 ◽  
Vol 137 (3) ◽  
Author(s):  
Andreas Lantz ◽  
Robert Collin ◽  
Marcus Aldén ◽  
Annika Lindholm ◽  
Jenny Larfeldt ◽  
...  
Keyword(s):  
Natural Gas ◽  
Combustion Chamber ◽  
Flame Front ◽  
Gas Turbines ◽  
Dynamic Pressure ◽  
Pressure Fluctuations ◽  
Burner Exit ◽  
Planar Laser ◽  
Industrial Gas Turbines ◽  
Dynamic Pressure Measurements

The effect of hydrogen enrichment to natural gas flames was experimentally investigated at atmospheric pressure conditions using flame chemiluminescence imaging, planar laser-induced fluorescence of hydroxyl radicals (OH PLIF), and dynamic pressure monitoring. The experiments were performed using a third generation dry low emission (DLE) burner used in both SGT-700 and SGT-800 industrial gas turbines from Siemens. The burner was mounted in an atmospheric combustion test rig at Siemens with optical access in the flame region. Four different hydrogen enriched natural gas flames were investigated; 0 vol. %, 30 vol. %, 60 vol. %, and 80 vol. % of hydrogen. The results from flame chemiluminescence imaging and OH PLIF show that the size and shape of the flame was clearly affected by hydrogen addition. The flame becomes shorter and narrower when the amount of hydrogen is increased. For the 60 vol. % and 80 vol. % hydrogen flames the flame has moved upstream and the central recirculation zone that anchors the flame has moved upstream the burner exit. Furthermore, the position of the flame front fluctuated more for the full premixed flame with only natural gas as fuel than for the hydrogen enriched flames. Measurements of pressure drop over the burner show an increase with increased hydrogen in the natural gas despite same air flow thus confirming the observation that the flame front moves upstream toward the burner exit and thereby increasing the blockage of the exit. Dynamic pressure measurements in the combustion chamber wall confirms that small amounts of hydrogen in natural gas changes the amplitude of the dynamic pressure fluctuations and initially dampens the axial mode but at higher levels of hydrogen an enhancement of a transversal mode in the combustion chamber at higher frequencies could occur.

Numerical Procedure for the Investigation of Combustion Dynamics in Industrial Gas Turbines: LES, RANS and Thermoacoustics

2015 ◽  
Author(s):  
Luca Rofi ◽  
Giovanni Campa ◽  
Vyacheslav Anisimov ◽  
Federico Daccá ◽  
Edoardo Bertolotto ◽  
...  
Keyword(s):  
Experimental Data ◽  
Gas Turbines ◽  
Numerical Procedure ◽  
Combustion System ◽  
Combustion Dynamics ◽  
Eddy Simulation ◽  
Experimental Apparatus ◽  
Industrial Gas Turbines ◽  
Computationally Intensive ◽  
Acoustic Instabilities

The necessity for a combustion system to work with premixed flames and its capability to cope with rapid load variations avoiding the occurrence of thermo-acoustic instabilities, has led to investigate the complex dynamic phenomena that occur during combustion. Thanks to numerical simulations it is possible to examine these complex mechanisms getting useful information to optimize the combustion system. The aim of this work is to describe a numerical procedure developed in Ansaldo Energia for the investigation of combustion dynamics occurring in Ansaldo Energia gas turbines. In this paper, firstly the experimental apparatus of a full scale atmospheric test rig equipped with Ansaldo Energia burner is described. Secondly, the flame behavior is studied by means of a Large Eddy Simulation (LES). Once the LES has reached a statistically stationary state, a forcing is added to the system to compute the Flame Transfer Function (FTF), in terms of amplitude n and delay time τ, related to initial phases of humming. Thirdly, the forced flame simulations are used as the input of an Helmholtz solver to analyze the acoustic behavior of the system, which is then compared to experimental data. Finally, to evaluate the feasibility of a less computationally intensive approach, a RANS simulation of the same configuration is described and the results are transferred to FEM (Finite Element Method) Helmholtz solver: a comparison between the LES approach and the RANS approach is carried out with reference to the experimental data.

Study on the Flow Characteristics of Transverse Injection in Cavity

2013 ◽  
Vol 291-294 ◽  
pp. 1940-1944
Author(s):  
Hai Jun Sun ◽  
Zhuo Xiong Zeng ◽  
Yi Hua Xu
Keyword(s):  
Flow Field ◽  
Total Pressure ◽  
Flow Characteristics ◽  
Mass Diffusion ◽  
Mixing Efficiency ◽  
Flame Stability ◽  
Fuel Distribution ◽  
Turbulence Flow ◽  
Transverse Injection

The combination of transverse injection and cavity flame stabilizer is a good way to improve the mixing efficiency and flame stability. In order to study the influence of transverse injection on the flow field of cavity in advanced vortex combustor, the turbulence flow and the fuel distribution under the influence of different assignments of jet holes were simulated numerically. The results show that the different assignments of jet holes have a bigger impact on the geometry and center of vortex, but lesser on the total pressure of combustor. The content of fuel reduces quickly in the jet direction, injection can improve the mixing of fuel and air. The phenomenon of mass diffusion and transport is obvious, it is in favor of flame stability.

Combustion System Update SGT5-4000F: Design, Testing and Validation

2013 ◽  
Author(s):  
Boris F. Kock ◽  
Bernd Prade ◽  
Benjamin Witzel ◽  
Holger Streb ◽  
Mike H. Koenig
Keyword(s):  
Gas Turbines ◽  
High Reliability ◽  
Product Development Process ◽  
Test Facility ◽  
Combustion System ◽  
Lean Premixed Combustion ◽  
Air Mixing ◽  
Acoustic Stability ◽  
Combustion Tests ◽  
Cooling Air

The first Siemens AG SGT5-4000F engine with hybrid burner ring combustor (HBR) was introduced in 1996. Since then, frequent evolutionary design improvements of the combustion system were introduced to fulfill the continuously changing market requirements. The improvements particularly focused on increased thermodynamic performance, reduced emissions, and increasing operational flexibility in terms of load gradients, fuel flexibility, and turndown capability. According to the Siemens product development process, every design evolution had to pass several validation steps to ensure high reliability and best performance. The single steps included cold flow and mixing tests at atmospheric pressure, high-pressure combustion tests in full-scale sector combustion test rigs, and full engine tests at the Berlin test facility (BTF). After successful validation, the design improvements were gradually released for commercial operation. In a first step, cooling air reduction features have been implemented in 2005, followed by the introduction of a premixed pilot as second step in 2006. Both together resulted in a significant reduction of the NOx emissions of the system. In a third step, an aerodynamic burner modification was introduced in 2007, which improved the thermo-acoustic stability of the system towards higher turbine inlet temperatures and adapted to fuel preheating to allow for increased cycle efficiency. All three features together have been released as package in 2010 and to date accumulated more than 50,000 operating hours (fleet leader 24,000). This paper reports upon the steps towards this latest design status of the SGT5-4000F and presents results from typical focus areas of lean premixed combustion systems in gas turbines including aero-dynamical optimization, fuel/air mixing improvements and cooling air management in the combustor.

Development of a Liquid Fuel Combustion System for SGT-750

2014 ◽  
Author(s):  
Olle Lindman ◽  
Mats Andersson ◽  
Magnus Persson ◽  
Erik Munktell
Keyword(s):  
Gas Turbines ◽  
Liquid Fuel ◽  
Cross Flow ◽  
Development Program ◽  
Medium Size ◽  
Combustion System ◽  
Gaseous Fuels ◽  
Air Mixing ◽  
Industrial Gas Turbines ◽  
Fuel Nozzle

This paper describes the latest results from the development of a liquid fuel solution for the 4th generation DLE system for Siemens medium size gas turbines. Gaseous fuels are the dominating fuels for industrial gas turbines. However, many customers need to be able to run on liquid fuel as backup. The demand for dry low NOx emissions when operating on liquid fuel is increasing. The aim for the 4th generation DLE system incorporated in the recently released SGT-750 [1] is to have emission levels well below market demands on both gas and liquid fuel. This paper will highlight the technical challenges when adding liquid fuel operation to a combustion system optimized for gas operation. The stand-alone spray characteristics for a liquid fuel nozzle is quite easy to predict, but the final combustion performance in a hot air cross flow environment is all but easy to predict by numerical simulations or cold flow tests [2]. Due to the complexity of the challenge, the development program focused on a selection of concepts for which fuel/air mixing calculations were made. The investigation was completed by testing in a full scale, single burner high pressure combustion test rig.

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.

Experimental Investigation of Performance of an Air Blast Atomizer by Planar Laser Sheet Imaging Technique

2013 ◽  
Vol 136 (2) ◽  
Author(s):  
Cunxi Liu ◽  
Fuqiang Liu ◽  
Yanhui Mao ◽  
Yong Mu ◽  
Gang Xu
Keyword(s):  
Swirling Flow ◽  
Fluid Dynamic ◽  
Laser Sheet ◽  
Pollutant Emissions ◽  
Space Distribution ◽  
Imaging Method ◽  
Spray Cone ◽  
Fuel Distribution ◽  
Planar Laser ◽  
Air Mixing

It is widely recognized that the fuel-air mixing process is a critical factor in improving combustion efficiency and in minimizing pollutants such as NOx. Enhancement of fuel-air mixing can lead to lower pollutant emissions and greater efficiency. However, swirling flows in lean combustors play the role of fuel-air mixing and flame stability. The complex fluid dynamic phenomena encountered in swirling two-phase flow contribute to the difficulty in complete understanding of the different processes occurring in combustors. Fortunately, optical and laser-based visualization techniques available in our lab are important nonintrusive tools for visualizing flow process, especially for fuel injection and fuel-air mixing. To provide for a better understanding of effects of counter-rotating flow on droplets in atomization process, this study is a detailed characterization of the spray generated by an airblast atomizer by planar laser sheet imaging method. Optical facility for spray diagnostics with fuel planar laser induced fluorescence (fuel-PLIF) method for fuel distribution and particle image velocimetry (PIV) method for the velocity of droplets is used to evaluate the performance of an airblast atomizer. The results show that the performance of secondary atomization is influenced by swirling flow and primary atomization simultaneously; the swirling flow exhibits significant influence on the droplet size and space distribution relative to that of primary atomization. The primary swirling air reopens the spray cone generated by pressure-swirl atomizer, and the secondary swirling air affects the fuel distribution by forming the recirculation zone. The results provide critical information for the design and development of combustion chambers.

Hydrogen as a Pilot Gas to Improve Power Turndown in Simulated Ultra Low NOx Gas Turbine Combustion

2007 ◽  
Author(s):  
Gordon E. Andrews ◽  
Eduardo Z. Delgadillo ◽  
Mike C. Mkpadi ◽  
Gary Hayes
Keyword(s):  
Natural Gas ◽  
Atmospheric Pressure ◽  
Gas Turbines ◽  
Energy Input ◽  
Co2 Reduction ◽  
Flame Stability ◽  
Nox Emissions ◽  
Total Energy Input ◽  
Pilot Fuel ◽  
Industrial Gas Turbines

The use of a central pilot with a well mixed radial swirler combustor was investigated, at 600K and atmospheric pressure, to improve the power turn down of a low NOx combustor design. Hydrogen was compared with natural gas as the pilot fuel, using between 11 and 29% of the total energy input as hydrogen pilot fuel. With natural gas at low powers there was a hydrocarbon and CO emissions problem, but good flame stability was achieved and there was flame propagation from the pilot to the well mixed main combustion. The use of hydrogen as a pilot gas resulted in a 90% reduction in the HC and CO emissions at the simulated low power conditions. However, there was a significant increase in NOx emissions. The use of hydrogen as a pilot is a simple way to introduce hydrogen into existing industrial gas turbines so that the CO2 reduction credits of 11–29% can be claimed, if the hydrogen comes from a renewable or carbon sequestrated source.

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