Investigation of Flame Stabilization in a High-Pressure Multi-Jet Combustor by Laser Measurement Techniques

2014 ◽  
Author(s):  
Oliver Lammel ◽  
Tim Rödiger ◽  
Michael Stöhr ◽  
Holger Ax ◽  
Peter Kutne ◽  
...  
Keyword(s):  
High Pressure ◽  
Natural Gas ◽  
Combustion Chamber ◽  
Gas Turbine ◽  
Recirculation Zone ◽  
Flame Stabilization ◽  
Operating Conditions ◽  
Pollutant Emissions ◽  
Single Shot ◽  
Optical Access

In this contribution, comprehensive optical and laser based measurements in a generic multi-jet combustor at gas turbine relevant conditions are presented. The flame position and shape, flow field, temperatures and species concentrations of turbulent premixed natural gas and hydrogen flames were investigated in a high-pressure test rig with optical access. The needs of modern highly efficient gas turbine combustion systems, i.e., fuel flexibility, load flexibility with increased part load capability, and high turbine inlet temperatures, have to be addressed by novel or improved burner concepts. One promising design is the enhanced FLOX® burner, which can achieve low pollutant emissions in a very wide range of operating conditions. In principle, this kind of gas turbine combustor consists of several nozzles without swirl, which discharge axial high momentum jets through orifices arranged on a circle. The geometry provides a pronounced inner recirculation zone in the combustion chamber. Flame stabilization takes place in a shear layer around the jet flow, where fresh gas is mixed with hot exhaust gas. Flashback resistance is obtained through the absence of low velocity zones, which favors this concept for multi-fuel applications, e.g. fuels with medium to high hydrogen content. The understanding of flame stabilization mechanisms of jet flames for different fuels is the key to identify and control the main parameters in the design process of combustors based on an enhanced FLOX® burner concept. Both experimental analysis and numerical simulations can contribute and complement each other in this task. They need a detailed and relevant data base, with well-known boundary conditions. For this purpose, a high-pressure burner assembly was designed with a generic 3-nozzle combustor in a rectangular combustion chamber with optical access. The nozzles are linearly arranged in z direction to allow for jet-jet interaction of the middle jet. This line is off-centered in y direction to develop a distinct recirculation zone. This arrangement approximates a sector of a full FLOX® gas turbine burner. The experiments were conducted at a pressure of 8 bar with preheated and premixed natural gas/air and hydrogen/air flows and jet velocities of 120 m/s. For the visualization of the flame, OH* chemiluminescence imaging was performed. 1D laser Raman scattering was applied and evaluated on an average and single shot basis in order to simultaneously and quantitatively determine the major species concentrations, the mixture fraction and the temperature. Flow velocities were measured using particle image velocimetry at different section planes through the combustion chamber.

Modeling of Turbulent Combustion and Radiative Heat Transfer in a Object-Oriented CFD Code for Gas Turbine Application

2008 ◽  
Author(s):  
Antonio Andreini ◽  
Matteo Cerutti ◽  
Bruno Facchini ◽  
Luca Mangani
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Radiative Heat Transfer ◽  
Turbulent Combustion ◽  
Radiative Heat ◽  
Object Oriented ◽  
Flame Stabilization ◽  
Operating Conditions ◽  
Pollutant Emissions ◽  
Combustion Models

One of the driving requirements in gas turbine design is the combustion analysis. The reduction of exhaust pollutant emissions is in fact the main design constraint of modern gas turbine engines, requiring a detailed investigation of flame stabilization criteria and temperature distribution within combustion chamber. At the same time, the prediction of thermal loads on liner walls continues to represent a critical issue especially with diffusion flame combustors which are still widely used in aeroengines. To meet such requirement, design techniques have to take advantage also of the most recent CFD tools that have to supply advanced combustion models according to the specific application demand. Even if LES approach represents a very accurate approach for the analysis of reactive flows, RANS computation still represents a fundamental tool in industrial gas turbine development, thanks to its optimal tradeoff between accuracy and computational costs. This paper describes the development and the validation of both combustion and radiation models in a object-oriented RANS CFD code: several turbulent combustion models were considered, all based on a generalized presumed PDF flamelet approach, valid for premixed and non premixed flames. Concerning radiative heat transfer calculations, two directional models based on the P1-Approximation and the Finite Volume Method were treated. Accuracy and reliability of developed models have been proved by performing several computations on well known literature test-cases. Selected cases investigate several turbulent flame types and regimes allowing to prove code affordability in a wide range of possible gas turbine operating conditions.

Fuel Flexibility Test Campaign on a GE10 Gas Turbine: Experimental and Numerical Results

2006 ◽  
Author(s):  
Antonio Andreini ◽  
Bruno Facchini ◽  
Luca Mangani ◽  
Stefano Cocchi ◽  
Roberto Modi
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Load Condition ◽  
Co2 Concentration ◽  
Flame Stabilization ◽  
Pollutant Emissions ◽  
Nox Emissions ◽  
Predictive Tool ◽  
Fuel Flexibility ◽  
Base Load

Medium- and low-LHV fuels are receiving a continuously growing interest in stationary power applications. Besides that, since in many applications the fuels available at a site can be time by time of significantly different composition, fuel flexibility has become one of the most important requirements to be taken into account in developing power systems. A test campaign, aimed to provide a preliminary assessment of a small power gas turbine’s fuel flexibility, was carried over a full-scale GE10 prototypical unit, located at the Nuovo-Pignone manufacturing site, in Florence. The engine is a single shaft, simple cycle gas turbine designed for power generation applications, rated at 11 MW electrical power and equipped with a silos-type combustor. A variable composition gas fuel was obtained by mixing natural gas with CO2 to about 40% by vol. at engine base-load condition. Tests involved two different diffusive combustion systems: the standard version, designed for operation with natural gas, and a specific system designed for low-LHV fuels. Tests performed aimed to investigate both ignition limits and combustors’ performances, focusing on hot parts’ temperatures and pollutant emissions. Regarding NOx emissions, data collected during standard combustor’s tests were matched a simple scaling law (as a function of cycle parameters and CO2 concentration in the fuel mixture), which can be used in similar applications as a NOx predictive tool. In a following step, a CFD study was performed in order to verify in detail the effects of LHV reduction on flame structure and to compare measured and calculated NOx. STAR-CD™ code was employed as main CFD solver while turbulent combustion and NOx models were specifically developed and implemented using STAR’s user-subroutine features. Both models are based on classical laminar-flamelet approach. Three different operating points were considered at base-load conditions, varying CO2 concentration (0%, 20% and 30% vol. simulated). Numerical simulations point out the flexibility of the GE10 standard combustor to assure flame stabilization even against large variation of fuel characteristics. Calculated NOx emissions are in fairly good agreement with measured data confirming the validity of the adopted models.

Fuel Nozzle Performance Analysis Using Laser Techniques and Combustion Chamber With Optical Access

2006 ◽  
Author(s):  
G. R. Pucher ◽  
P. R. Underhill ◽  
W. D. Allan ◽  
G. Wang ◽  
S. Guy
Keyword(s):  
Combustion Chamber ◽  
Gas Turbine ◽  
Scattered Light ◽  
Laser Sheet ◽  
Video Camera ◽  
Operating Conditions ◽  
Cross Sectional ◽  
Efficient Operation ◽  
Spray Pattern ◽  
Optical Access

Correct functioning of fuel nozzles is paramount to the efficient operation of gas turbine engines. Nozzles exhibiting poor distribution of droplets can be detrimental to combustion and overall engine life due to the creation of hot spots and potential for torching. The traditional technique of assessing nozzle performance involves operation in stagnant air conditions. Fuel spray is collected in the subdivided bins of a mechanical patternation system to determine spray symmetry. Recent improvements in spray analysis involve the use of laser light sheets to illuminate specific ‘slices’ of sprays in either cross sectional or axial planes. Typically, scattered light from the intersection of a laser sheet and a spray is recorded by a digital video camera, and images are averaged and corrected to determine the quality of the spray pattern. Such optical means of assessing spray quality provide great improvement over conventional means in terms of speed, convenience, and information retrieved. Nonetheless, data obtained in stagnant air conditions do not give an indication of spray geometry within combustion chambers under realistic operating conditions of airflow and combustion. This paper describes a project which applied laser-based optical patternation in a T-56 gas turbine combustion chamber rig with optical access under realistic flow conditions. As such, nozzle spray pattern was observed for various air and fuel flows in both cross sectional and plume (chamber axial) orientations. A deliberately damaged nozzle was also assessed for comparison with a good nozzle. Using optical filtration, spray patterns were observed under operationally representative combustion conditions.

CFD Analysis of an Annular Micro Gas Turbine Combustion Chamber Fuelled With Liquid Biofuels: Preliminary Results With Bioethanol

2013 ◽  
Author(s):  
Paolo Laranci ◽  
Gianni Bidini ◽  
Umberto Desideri ◽  
Francesco Fantozzi
Keyword(s):  
Natural Gas ◽  
Combustion Chamber ◽  
Gas Turbine ◽  
Internal Combustion Engines ◽  
Oxidation Mechanism ◽  
Biodiesel Production ◽  
Pollutant Emissions ◽  
Cfd Analysis ◽  
Micro Gas Turbine ◽  
Preliminary Results

Liquid biofuels, such as bioethanol, biodiesel and vegetal oils, can effectively be used in internal combustion engines blended with liquid fuels of fossil origin or in their substitution, allowing a reduction of CO2 and pollutant emissions in the atmosphere. This work is supported by a CFD analysis to study the feasibility of using these fuels derived from biomass in a 80 kWel micro gas turbine, originally designed for operation with natural gas. In this paper preliminary results about the behavior of bioethanol in the MGT combustion chamber are presented. The complete investigation however includes biodiesel and also glycerin, a byproduct of biodiesel production. To carry out the computational simulations, combustion models included in a commercial software and oxidation mechanism of ethanol taken from the literature were used. The geometry of the NG injector was modified to optimize the liquid inlet into the combustor. Simulation results in terms of temperatures, pressures, and emissions were compared with data available for natural gas combustion in the original combustion chamber.

scholarly journals 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):  
High Pressure ◽  
Natural Gas ◽  
Gas Turbine ◽  
Distribution System ◽  
Gas Turbines ◽  
Liquid Fuel ◽  
Flame Stabilization ◽  
Experimental Investigations ◽  
Dual Fuel ◽  
Combustion System

Abstract Industrial gas turbines like the MGT6000 are often operated as power supply or as mechanical drives for pumps and compressors at remote locations on islands and in deserts. Moreover, small gas turbines are used in CHP applications with a high need for availability. 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 already capable of ultra-low NOx emissions for a variety of gaseous fuels. This system has been further developed to provide dry dual fuel capability to the MGT family. 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, without the need for any additional atomizing air. The pilot stage is continuously operated to support further the flame stabilization across the load range, whereas the bulk of the liquid fuel is injected through the premixed combustor stage. The premixed stage comprises a set of four decentralized nozzles placed at the exit of the main air swirler. These premixed nozzles are based on fluidic oscillator atomizers, wherein a rapid and effective atomization of the liquid fuel is achieved through self-induced oscillations of the liquid fuel stream. We present results of numerical and experimental investigations performed in the course of the development process illustrating the spray, hydrodynamic, and thermal performance of the pilot injectors. Extensive testing of the burner at atmospheric and full load high-pressure conditions has been performed, before verification of the whole combustion system within full engine tests. The burner shows excellent emission performance (NOx, CO, UHC, soot) without additional water injection, while maintaining the overall natural gas performance. Soot and particle emissions, quantified via several methods, are well below legal restrictions. Furthermore, when not in liquid fuel operation, a continuous purge of the injectors based on compressor outlet (p2) air has been laid out. Generic atmospheric coking tests were conducted before verifying the purge system in full engine tests. Thereby we completely avoid the need for an additional high-pressure auxiliary compressor or demineralized water. We show the design of the fuel supply and distribution system. We designed it to allow for rapid fuel switchovers from gaseous fuel to liquid fuel, and for sharp load jumps. Finally, we discuss the integration of the dual fuel system into the standard gas turbine package of the MGT6000 in detail.

Flow Analysis of High Pressure Catalytic Combustor for Gas Turbine

1995 ◽  
Author(s):  
Y. Tsujikawa ◽  
S. Fujii ◽  
H. Sadamori ◽  
S. Ito ◽  
S. Katsura
Keyword(s):  
High Pressure ◽  
Natural Gas ◽  
Gas Turbine ◽  
Flow Analysis ◽  
Methane Combustion ◽  
Single Step ◽  
Operating Conditions ◽  
Experimental Investigations ◽  
Gas Temperature ◽  
Radial Convection

The objective of this paper is modeling the mechanism of high temperature catalytic oxidation of natural gas, or methane. The model is two-dimensional steady-state, and includes axial and radial convection and diffusion of mass, momentum and energy, as well as homogeneous (gas phase) and heterogeneous (gas-surface) single step irreversible chemical reactions within a catalyst channel. Experimental investigations were also made of natural gas, or methane combustion in the presence of Mn-substituted hexaaluminate catalysts. Axial profiles of catalyst wall temperature, and gas temperature and gas composition for a range of gas turbine combustor operating conditions have been obtained for comparison with and development of a computer model of catalytic combustion. Numerical calculation results for low pressure agree well with experimental data. The calculations have been extended for high pressure (10 atms) operating conditions of gas turbine.

scholarly journals LES Analysis of CO Emissions from a High Pressure Siemens Gas Turbine Prototype Combustor at Part Load

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5751
Author(s):  
Pascal Gruhlke ◽  
Christian Beck ◽  
Bertram Janus ◽  
Andreas M. Kempf
Keyword(s):  
Carbon Monoxide ◽  
High Pressure ◽  
Combustion Chamber ◽  
Gas Turbine ◽  
Operating Conditions ◽  
Part Load ◽  
Tracer Particles ◽  
Flame Quenching ◽  
Operating Points ◽  
Co Concentrations

This work contributes to the understanding of mechanisms that lead to increased carbon monoxide (CO) concentrations in gas turbine combustion systems. Large-eddy simulations (LES) of a full scale high pressure prototype Siemens gas turbine combustor at three staged part load operating conditions are presented, demonstrating the ability to predict carbon monoxide pollutants from a complex technical system by investigating sources of incomplete CO oxidation. Analytically reduced chemistry is applied for the accurate pollutant prediction together with the dynamic thickened flame model. LES results show that carbon monoxide emissions at the probe location are predicted in good agreement with the available test data, indicating two operating points with moderate pollutant levels and one operating point with CO concentrations below 10 ppm. Large mixture inhomogeneities are identified in the combustion chamber for all operating points. The investigation of mixture formation indicates that fuel-rich mixtures mainly emerge from the pilot stage resulting in high equivalence ratio streaks that lead to large CO levels at the combustor outlet. Flame quenching due to flame-wall-interaction are found to be of no relevance for CO in the investigated combustion chamber. Post-processing with Lagrangian tracer particles shows that cold air—from effusion cooling or stages that are not being supplied with fuel—lead to significant flame quenching, as mixtures are shifted to leaner equivalence ratios and the oxidation of CO is inhibited.

FLOX® Combustion at High Pressure With Different Fuel Compositions

2007 ◽  
Author(s):  
Rainer Lu¨ckerath ◽  
Wolfgang Meier ◽  
Manfred Aigner
Keyword(s):  
High Pressure ◽  
Natural Gas ◽  
Gas Turbine ◽  
Flue Gas ◽  
Operating Conditions ◽  
Atmospheric Conditions ◽  
Relative Temperature ◽  
Planar Laser ◽  
Gas Recirculation ◽  
First Time

In Flameless Oxidation (FLOX®) the combustion is distributed over a large volume by a high internal flue gas recirculation. This technology has been successfully used for many years in technical furnaces under atmospheric conditions with very low NOx emissions. In the work presented here, FLOX® combustion was for the first time investigated at high pressure in order to assess its applicability for gas turbine combustors. A FLOX® burner was equipped with a combustion chamber with quartz windows and installed into a high pressure test rig with optical access. The burner was operated under typical gas turbine conditions at pressure of 20 bar with thermal powers up to 475 kW. Natural gas as well as mixtures of natural gas and H2 were used as fuel. The NOx and CO emissions were recorded for the different operating conditions. OH* chemiluminescence imaging and planar laser-induced fluorescence of OH were applied in order to characterize the flame zone and the relative temperature distributions. The combustion behaviour was investigated as a function of equivalence ratio and fuel composition, and the influence of the gas inlet velocity on mixing and emissions was studied. For various operating conditions the lean extinction limits were determined.

Experimental and Numerical Investigations of Novel Natural Gas Low NOx Burners for Heavy Duty Gas Turbine

2018 ◽  
Author(s):  
Matteo Cerutti ◽  
Giovanni Riccio ◽  
Antonio Andreini ◽  
Riccardo Becchi ◽  
Bruno Facchini ◽  
...  
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Swirling Flow ◽  
Dynamic Pressure ◽  
Flame Structure ◽  
Flame Stabilization ◽  
Pollutant Emissions ◽  
Design Parameters ◽  
Geometrical Parameters ◽  
Moderate Pressure

A novel dry low-NOx gas turbine technology requires well balanced assessments since the early development phases. The weak knowledge of often conflicting aspects, such as operability and manufacturability, make any roadmap difficult to be drawn. The introduction of innovative manufacturing technologies such as the Direct Metal Laser Sintering (DMLS) process allows rapid manufacturing of components and test them in dedicated facilities to support real-time development of new products. The use of such a manufacturing process allows the adoption of designed experiments based development strategies, which are still uncommon at industrial level, due to the reduced time from drawings to test. The paper describes a reactive test campaign performed by BHGE in cooperation with University of Florence, aimed at the exploration of capabilities of different innovative burners in terms of pollutant emissions containment and blow-out margin. In particular, the test campaign has been conceived to provide a robust estimate of the effects of key geometrical parameters on principal burner performances. The flame stabilization mechanism of the investigated burners is based on the swirling flow generated by different setup of two internal channels: co-rotating and counter-rotating radial and axial swirlers. The effect of both the shape and the size of the internal air passages, as well as of the swirler characteristics, has been matter of investigation. Burners were tested in a single-cup test rig operated at moderate pressure conditions (up to 6bar), with two levels of preheated air temperature (300°C and 400°C). Each burner was equipped with two natural gas feeding lines representing the diffusion (pilot) and premixed (main) fuel supplies: both lines were regulated during tests to assess the effect of fuel split on emissions and to identify a stable low-NOx operating window, within which a lean blow-out test was performed. Dynamic pressure probes, were used to evaluate the onset of combustion instabilities. The burner development was supported by CFD investigations with the purpose to have a detailed understating of the flow-field and flame structure and to perform a preliminary screening to select the most promising solutions for the testing phase. The post process of the experimental results has allowed to correlate the main design parameters to burner performance variables discovering possible two-fold optimizations in terms of emissions and operability.

Experimental Investigations of Flame Stabilization of a Gas Turbine Combustor

2011 ◽  
Author(s):  
Rainer Lu¨ckerath ◽  
Oliver Lammel ◽  
Michael Sto¨hr ◽  
Isaac Boxx ◽  
Ulrich Stopper ◽  
...  
Keyword(s):  
Natural Gas ◽  
Flow Field ◽  
Gas Turbine ◽  
Mixture Fraction ◽  
Flame Stabilization ◽  
Operating Conditions ◽  
Diagnostic Methods ◽  
Laser Raman Spectroscopy ◽  
Experimental Investigations ◽  
Combustion System

While today’s gas turbine (GT) combustion systems are designed for specific fuels there is an urgent demand for fuel-flexible stationary GT combustors capable of burning natural gas as well as hydrogen-rich fuels in future. For the development of a fuel flexible, low-emission, and reliable combustion system a better understanding of the flow field – flame interaction and the flame stabilization mechanism is necessary. For this purpose, a down-scaled staged can combustion system provided with an optical combustion chamber was investigated in a high pressure test rig. Different optical diagnostic methods were used to analyze the combustion behavior with a focus on flame stabilization and to generate a comprehensive set of data for validation of numerical simulation methods (CFD) employed in the industrial design process. For different operating conditions the size and position of the flame zone were visualized by OH* chemiluminescence measurements. Additionally, the exhaust gas emissions (NOx and CO) and the acoustic flame oscillations were monitored. Besides many different operating conditions with natural gas different fuel mixtures of natural gas and hydrogen were investigated in order to characterize the flashback behavior monitored with OH* chemiluminescence. For selected operating conditions detailed laser diagnostic experiments were performed. The main flow field with the inner recirculation zone was measured with two-dimensional particle image velocimetry (PIV) in different measuring planes. One-dimensional laser Raman spectroscopy was successfully applied for the measurement of the major species concentration and the temperature. These results show the variation of the local mixture fraction allowing conclusions to be drawn about the good premix quality. Furthermore, mixing effects of unburnt fuel/air and fully reacted combustion products are studied giving insights into the process of the turbulence-chemistry interaction and reaction progress.

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