Environmentally Friendly Update of Gas Turbines on Gas Transmission Lines

Author(s):  
S. Vesely´ ◽  
A. Soudarev ◽  
E. Vinogradov ◽  
Y. Zacharov

Currently, more than 1,500 gas turbines are in operation on natural gas transmission lines all over Europe. These turbines do not comply with the requirements for toxic substances content in exhaust gases. Therefore, an environmentally friendly update of these turbines is a hot topic now, especially because these turbines are supposed to remain in operation for another 10 or 15 years. Besides, environmentally friendly update is a specific issue that differs from the development of a new low-emission combustion chamber. The authors participated in environmentally friendly update of more than 500 gas turbines of this design in Russia, Ukraine, Slovakia, Czech Republic, Germany, and Hungary. As new emission limits are expected to be issued in the EU, a new low-emission burner was developed that makes use of a combination of kinetic and diffusion combustion to achieve low NOx and CO emissions. The burner operation in combustion chambers of gas turbines is characterized by a wide range of the coefficient of excess air from idle run to full performance. Therefore, the control of the quantity of primary air is necessary. The paper will describe the main stages of the burner research. Tests were performed on an atmospheric pressure test rig where the basic characteristics were gained. The influence of pressure was examined on a special test rig at 0.75–1.1 MPa of pressure. Tests have confirmed that the required NOx and CO emission limits can be achieved with the designed burner. The low emission burner was used for the combustion chamber of a 6 MW gas turbine. The tests performed on a part of a model burner will be presented and an analysis of measurement results will be given.

Author(s):  
S. Vesely´ ◽  
S. Pary´zek ◽  
E. Vinogradov ◽  
Y. Zakharov ◽  
A. Soudarev

The environmentally friendly modification of gas turbine combustion chambers is a process for altering the structure of combustion, mainly in the primary zone in order to reduce the emission of NOx, CO, and solids into the atmosphere. The ecological modernization of gas turbines that are currently in operation is a continually topical subject because there are several thousand turbine units in Europe that do not meet current emission limits. At the same time, it can be expected that the emission limits for these turbines operating in the European Union will be reduced to NOx≤75 mg/m3, CO≤100 mg/m3 in working range of 40–100% of the gas turbine output after the year 2010. The authors have developed a new construction of a hybrid low-emission natural gas burner. Developmental work was performed both on one burner and also in a burner group consisting of seven hybrid burners. Results will be presented in this paper for model conditions for the atmospheric test rig and their re-calculation to the operational parameters on the real gas turbine. A conception with variable primary section combustion chamber geometry has been used to achieve low emissions in a wide range of gas turbine output allowing the organization of the combustion process with a constant gas/air mixing ratio coefficient. A prototype of a combustion chamber with a hybrid burner group with control of the primary air mass flow has been manufactured and tested in a 6 MW gas turbine operating in a gas pipeline compressor plant. The achieved emission characteristics will be presented and compared with precalculations. The experiments made on the real gas turbine have proven the possibility of meeting the target emission limit performance of NOx≤50 mg/m3, CO≤50 mg/m3. Other possibilities how to reduce harmful emissions for this burner type will be presented in this paper.


Author(s):  
Marek Dzida ◽  
Krzysztof Kosowski

In bibliography we can find many methods of determining pressure drop in the combustion chambers of gas turbines, but there is only very few data of experimental results. This article presents the experimental investigations of pressure drop in the combustion chamber over a wide range of part-load performances (from minimal power up to take-off power). Our research was carried out on an aircraft gas turbine of small output. The experimental results have proved that relative pressure drop changes with respect to fuel flow over the whole range of operating conditions. The results were then compared with theoretical methods.


Author(s):  
Martin Hauser ◽  
Manuel Lorenz ◽  
Thomas Sattelmayer

Modern large gas turbines for power generation have multiple burners, which are distributed around the circumference of the engine and which generate flames in combustors of either annular or can-annular geometry. In both cases, considering only the axial modes has proven to be insufficient for the assessment of the thermoacoustic stability. An adequate analysis requires consideration of the circumferential acoustic coupling generated by the acoustic field in the upstream and downstream annuli and the open passages between the cans, respectively. As in annular combustors, the particularly critical eigenmodes with low frequencies are predominantly of circumferential nature; the stability of annular combustors is often governed by the onset of circumferential acoustic oscillations. To determine the influence of these circumferential acoustic modes on the dynamic flame behavior, a new single burner test rig was developed. The unique acoustic properties of the test rig allow the exposure of a single swirl burner to a two-dimensional acoustic field that resembles the circumferential mode in an annular combustor. Measurements were performed for axial as well as transversal excitation of the burner and the combination of both. To investigate the dynamic flame structure, phase-resolved flame images have been evaluated in terms of amplitude and phase distribution. Under transversal excitation, the flame structure becomes highly asymmetrical. A region of higher OH∗ intensity is generated in the combustion chamber, which rotates with the excitation frequency. From phase-resolved particle image velocimetry (PIV) measurements of the isothermal flow, it is concluded that the transversal excitation modulates the swirl generation leading to an asymmetrical velocity distribution in the burner nozzle and the combustion chamber.


Author(s):  
Hans-Christoph Ries ◽  
Mateus Vieira Carlesso ◽  
Christian Eigenbrod ◽  
Stephen Kroll ◽  
Kurosch Rezwan

This paper discusses the potential of using porous ceramic lining as insulating material in combustion chambers with respect to their sound absorbent ability to suppress thermoacoustic instabilities. For this purpose a combustion chamber test rig was developed and different types of ceramic linings were tested. The examined range of power was between 40 and 250 kW and the air-propane equivalence ratio was between 1.2 and 2.0. The overall sound pressure level and frequency domain of a lean premixed swirl stabilized and piloted burner are presented. The resonance frequencies and sound pressure levels are obtained and compared for the different combustion chamber linings. The results show a significant decrease in overall sound pressure level by up to 23.5 dB for sound absorbent lining in comparison to the common sound reflecting combustion chamber lining. In summary, sound absorbent ceramic combustion chamber lining can contribute to improve the stability of lean premixed gas turbines.


1978 ◽  
Author(s):  
R. J. Russell ◽  
J. J. Witton

A study has been made of the turbine erosion problem encountered in a marinized aero gas turbine which arose from the change of fuel type necessitated by the marine application. The work has involved the development of a technique for collecting carbon shed from the combustion chamber under engine operating conditions. Tests using the collector were made with a single combustor test rig and compared to engine experience. Combustion chamber modifications were developed having low solids emissions and their emissions characterized using the collector. The data from the collector show that smaller particles than hitherto collected can produce significant long-term erosion and that reduction on both size and quantity of particles is necessary to reduce erosion to acceptable levels. The data obtained in this study are compared with other published information on the basic erosion process and erosion in gas turbines by natural mineral dusts. The implications of the results to current and future engines are discussed.


Author(s):  
D. Filsinger ◽  
A. Schulz ◽  
S. Wittig ◽  
C. Taut ◽  
H. Klemm ◽  
...  

A further increase of thermal efficiency and a reduction of the exhaust emissions of ground based gas turbines can be achieved by introducing new high temperature resistant materials. Therfore, ceramics are under international development. They offer excellent strengths at room and elevated temperatures. For gas turbine combustor applications, however, these materials have to maintain their advantageous properties under hostile environment. For the assessment and comparison of the oxidation behavior of different nonoxide ceramic materials a test rig was developed at the Institute for Thermal Turbomachinery (ITS), University of Karlsruhe, Germany. The test rig was integrated into the high temperature/ high pressure laboratory. A ceramic model combustion chamber was designed which allowed the exposure of standard four-point flexure specimens to the hot combustion gas flow. Gas temperatures and pressures could be varied in a wide range. Additionally, the partial steam pressure could be adjusted to real combustor conditions. The present paper gives a detailed description of the test rig and presents results of 100 hours endurance tests of ceramic materials at 1400°C. The initial strengths and the strengths after oxidation tests are compared. In addition to this, photographs illustrating the changes of the material’s microstructure are presented.


Author(s):  
Frank Reiss ◽  
Sven-Hendrik Wiers ◽  
Ulrich Orth ◽  
Emil Aschenbruck ◽  
Martin Lauer ◽  
...  

This paper describes the development and test results of the low emission combustion system for the new industrial gas turbines in the 6–7 MW class from MAN Diesel & Turbo. The design of a robust combustion system and the achievement of very low emission targets were the most important design goals of the combustor development. During the design phase, the analysis of the combustor (i.e. burner design, air distribution, liner cooling design) was supported with different CFD tools. This advanced Dry Low Emission can combustion system (ACC) consists of 6 cans mounted externally on the gas turbine. The behavior and performance of a single can sector was tested over a wide load range and with different boundary conditions; first on an atmospheric test rig and later on a high pressure test rig with extensive instrumentation to ensure an efficient test campaign and accurate data. The atmospheric tests showed a very good performance for all combustor parts and promising results. The high pressure tests demonstrated very stable behavior at all operation modes and very low emissions to satisfy stringent environmental requirements. The whole operation concept of the combustion system was tested first on the single-can high pressure test bed and later on twin and single shaft gas turbines at MAN’s gas turbine test facility. During the engine tests, the can combustors demonstrated the expected combustion performance under real operation conditions. All emissions and performance targets were fully achieved. On the single shaft engine, the combustors were running with single digit ppm NOx levels between 50% and 100% load. The validation phase and further optimization of the gas turbines and the engine components are ongoing. The highlights of the development process and results of the combustor and engine tests will be presented and discussed within this paper.


Author(s):  
Stefan Bauer ◽  
Balbina Hampel ◽  
Thomas Sattelmayer

Abstract Vortex generators are known to be effective in augmenting the mixing of fuel jets with air. The configuration investigated in this study is a tubular air passage with fuel injection from one single orifice placed in the side wall. In the range of typical gas turbine combustor inlet temperatures, the performance vortex generator premixers (VGPs) have already been investigated for natural gas as well as for blends of natural gas and hydrogen. However, for highly reactive fuels, the application of VGPs in recuperated gas turbines is particularly challenging because the high combustor inlet temperature leads to potential risk with regard to premature self-ignition and flame flashback. As the current knowledge does not cover the temperature range far above the self-ignition temperature, an experimental investigation of the operational limits of VGPs is currently being conducted at the Thermodynamics Institute of the Technical University of Munich, Garching, Germany, which is particularly focused on reactive fuels and the thermodynamic conditions present in recuperated gas turbines with pressure ratios of 4–5. For the study presented in this paper, an atmospheric combustion VGP test rig has been designed, which facilitates investigations in a wide range of operating conditions in order to comply with the situation in recuperated microgas turbines (MGT), namely, global equivalence ratios between 0.2 and 0.7, air preheating temperatures between 288 K and 1100 K, and air bulk flow rates between 6 and 16 g/s. Both the entire mixing zone in the VGP and the primary combustion zone of the test rig are optically accessible. High-speed OH* chemiluminescence imaging is used for the detection of the flashback and blow-off limits of the investigated VGPs. Flashback and blow-off limits of hydrogen in a wide temperature range covering the autoignition regime are presented, addressing the influences of equivalence ratio, air preheating temperature, and momentum ratio between air and hydrogen on the operational limits in terms of bulk flow velocity. It is shown that flashback and blow-off limits are increasingly influenced by autoignition in the ultrahigh temperature regime.


Author(s):  
Stefan Bauer ◽  
Balbina Hampel ◽  
Thomas Sattelmayer

Vortex generators are known to be effective in augmenting the mixing of fuel jets with air. The configuration investgated in this study is a tubular air passage with fuel injection from one single orifice placed in the side wall. In the range of typical gas turbine combustor inlet temperatures, the performance vortex generator premixers (VGPs) have already been investigated for natural gas as well as for blends of natural gas and hydrogen. However, for highly reactive fuels, the application of VGPs in recuperated gas turbines is particularly challenging because the high combustor inlet temperature leads to potential risk with regard to premature self-ignition and flame flashback. As the current knowledge does not cover the temperature range far above the self-ignition temperature, an experimental investigation of the operational limits of VGPs is currently being conducted at the Thermodynamics Institute of the Technical University of Munich, which is particularly focused on reactive fuels and the thermodynamic conditions present in recuperated gas turbines with pressure ratios of 4–5. For the study presented in the paper, an atmospheric combustion VGP test rig has been designed, which facilitates investigations in a wide range of operating conditions in order to comply with the situation in recuperated micro gas turbines, namely global equivalence ratios between 0.2 and 0.7, air preheating temperatures between 288K and 1100K, and air bulk flow rates between 6–16 g/s. Both the entire mixing zone in the VGP and the primary combustion zone of the test rig are optically accessible. High speed OH* chemiluminescence imaging is used for the detection of the flashback and blow-off limits of the investigated VGPs. Flashback and blow-off limits of hydrogen in a wide temperature range covering the auto-ignition regime are presented, addressing the influences of equivalence ratio, air preheating temperature and momentum ratio between air and hydrogen on the operational limits in terms of bulk flow velocity. It is shown that flashback and blow-off limits are increasingly influenced by auto-ignition in the ultra-high temperature regime.


Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1794
Author(s):  
Bruno Schneider ◽  
Christian Schürch ◽  
Konstantinos Boulouchos ◽  
Stefan Herzig ◽  
Marc Hangartner ◽  
...  

A new test rig has been designed, built and commissioned, and is now jointly pursued to facilitate experimental investigations into advanced combustion processes (i.e., dual fuel, multi-mode) under turbulent conditions at high, engine-like temperature and pressure levels. Based on a standard diesel engine block, it offers much improved optical access to the in-cylinder processes due to its separated and rotated arrangement of the compression volume and combustion chamber, respectively. A fully variable pneumatic valve train and the appropriate preconditioning of the intake air allows it to represent a wide range of engine-like in-cylinder conditions regarding pressures, temperatures and turbulence levels. The modular design of the test rig facilitates easy optimizations of the combustion chamber/cylinder head design regarding different experimental requirements. The name of the new test rig, Flex-OeCoS, denotes its Flexibility regarding Optical engine Combustion diagnostics and/or the development of corresponding Sensing devices and applications. Measurements regarding in-cylinder gas pressures, temperatures and the flow field under typical operating conditions are presented to complete the description and assessment of the new test rig.


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