GAS TURBINE LEAN PREMIXED COMBUSTION: PRINCIPLES OF MODELLING IN THE CONTEXT OF THE KOLMOGOROV'S LEGACY IN TURBULENCE

2016 ◽  
Author(s):  
V. L. Zimont
Keyword(s):  
Gas Turbine ◽  
Premixed Combustion ◽  
Lean Premixed Combustion ◽  
Lean Premixed

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.

scholarly journals Experimental Evaluation of a Low Emissions, Variable Geometry, Small Gas Turbine Combustor

1990 ◽  
Author(s):  
K. O. Smith ◽  
M. H. Samii ◽  
H. K. Mak
Keyword(s):  
Gas Turbine ◽  
Experimental Evaluation ◽  
Premixed Combustion ◽  
Nox Emissions ◽  
Variable Geometry ◽  
Test Results ◽  
Gas Turbine Combustor ◽  
Lean Premixed Combustion ◽  
Primary Zone ◽  
Lean Premixed

The results of an on-engine evaluation of an ultra-low NOx, natural gas-fired combustor for a 200 kW gas turbine are presented. The combustor evaluated used lean-premixed combustion to reduce NOx emissions and variable geometry to extend the range over which low emissions were obtained. Test results showed that ultra-low NOx emissions could be achieved from full load down to approximately 50% load through the combination of lean-premixed combustion and variable primary zone airflow.

3D RANS Simulation and the Prediction by CRN Regarding NOx in a Lean Premixed Combustion in a Gas Turbine Combustor

2011 ◽  
Vol 35 (12) ◽  
pp. 1257-1264
Author(s):  
Jae-Bok Yi ◽  
Dae-Ro Jeong ◽  
Kang-Yul Huh ◽  
Jae-Min Jin ◽  
Jung-Kyu Park ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Premixed Combustion ◽  
Gas Turbine Combustor ◽  
Lean Premixed Combustion ◽  
Rans Simulation ◽  
Lean Premixed

Autoignition of Hydrogen and Air Inside a Continuous Flow Reactor With Application to Lean Premixed Combustion

2008 ◽  
Vol 130 (5) ◽  
Author(s):  
D. J. Beerer ◽  
V. G. McDonell
Keyword(s):  
Gas Turbine ◽  
Ignition Delay ◽  
Flow Reactor ◽  
Initial Conditions ◽  
Premixed Combustion ◽  
Nox Formation ◽  
Lean Premixed Combustion ◽  
Ignition Delay Times ◽  
Delay Times ◽  
Lean Premixed

With the need to reduce carbon emissions such as CO2, hydrogen is being examined as potential “clean” fuel for the future. One potential strategy is lean premixed combustion, where the fuel and air are allowed to mix upstream before entering the combustor, which has been proven to curb NOx formation in natural gas fired engines. However, premixing hydrogen and air may increase the risk of autoignition before the combustor, resulting in serious engine damage. A flow reactor was set up to test the ignition delay time of hydrogen and air at temperatures relevant to gas turbine engine operations to determine maximum possible mixing times. The results were then compared to past experimental work and current computer simulations. The current study observed that ignition is very sensitive to the initial conditions. The ignition delay times follow the same general trend as seen in previous flow reactor studies: ignition within hundreds of milliseconds and relatively low activation energy. An experimentally derived correlation by Peschke and Spadaccini (1985, “Determination of Autoignition and Flame Speed Characteristics of Coal Gases Having Medium Heating Values,” Research Project No. 2357-1, Report No. AP-4291) appears to best predict the observed ignition delay times. Homogenous gas phase kinetics simulations do not appear to describe ignition well in these intermediate temperatures. Therefore, at the moment, only the current empirical correlations should be used in predicting ignition delay at engine conditions for use in the design of gas turbine premixers. Additionally, fairly large safety factors should still be considered for any design to reduce any chance of autoignition within the premixer.

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.

Suppression of Dynamic Combustion Instabilities by Passive and Active Means

2000 ◽  
Author(s):  
Peter Berenbrink ◽  
Stefan Hoffmann
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Premixed Combustion ◽  
Combustion Instabilities ◽  
Active System ◽  
Lean Premixed Combustion ◽  
Exit Nozzle ◽  
Lean Premixed ◽  
Dynamic Combustion ◽  
Suppression Of Combustion

In the gas turbine industry, lean premixed combustion is a state-of-the-art technology for the reduction of NOx emissions. Due to the ever increasing reaction densities and turbine inlet temperatures in modern gas turbines, the combustors reveal an increased tendency to form dynamic combustion instabilities. This paper reports on the use of passive and active methods for the suppression of combustion oscillations in heavy-duty gas turbines featuring lean premixed combustion: Modifications of the burner exit nozzle are implemented in order to avoid fluiddynamic feedback and to change the acoustic behavior of the flame. An asymmetric circumferential distribution of flames with different thermoacoustic responses serves to avoid or at least attenuate the self-excitation within the combustor in multiburner systems. In some applications, these methods are successfully coupled with an active system for the suppression of combustion instabilities (AIC) to further extend the operation envelope. Field demonstrations in different Siemens gas turbines serve to demonstrate the benefit and flexibility of these measures for practical gas turbine combustion systems.

Application of Thermal Oxidation to a Recuperated Gas Turbine: The Path to PPB NOx Emissions

2013 ◽  
Author(s):  
Jeffrey Armstrong ◽  
Douglas Hamrin ◽  
Steve Lampe
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Fuel Injection ◽  
Landfill Gas ◽  
Premixed Combustion ◽  
Nox Emissions ◽  
Single Digit ◽  
Lean Premixed Combustion ◽  
Lean Premixed ◽  
Order Of Magnitude

Dry, low NOx emissions developments in the industrial gas turbine industry have focused on lean-premixed combustion to reduce NOx to single digit parts-per-million (ppmV) emissions. The reduction of thermal NOx is limited by the lowest lean-premix combustion temperatures. To overcome this limit, a thermal oxidizer is applied which can oxidize hydrocarbon fuels at temperatures below those of lean-premixed combustion in a Brayton cycle. This oxidation technique is explained in a combustion taxonomy model. This paper presents the historical development and demonstration of technology with two different recuperated gas turbines operating on landfill gas. A unique fuel-injection strategy was used to introduce the fuel into the inlet of the gas turbine’s air compressor. The technology demonstrated an order-of-magnitude reduction in the emissions of NOx to the parts-per-billion range.

Pulsations in Gas Turbine Operation: Identification and Modeling With the Purpose of Online Engine Monitoring and Optimization

2017 ◽  
Author(s):  
Frank S. Weidner ◽  
Moritz Lipperheide ◽  
Manfred C. Wirsum ◽  
Stefano Bernero ◽  
Martin Gassner
Keyword(s):  
Root Mean Square Error ◽  
Gas Turbine ◽  
Mean Square Error ◽  
Root Mean Square ◽  
Premixed Combustion ◽  
Mean Square ◽  
Lean Premixed Combustion ◽  
Lean Premixed ◽  
Term Data

Lean premixed combustion has become state of the art technology in gas turbines for power generation because of its very low emission potential in the context of tightening pollutant emissions regulations. Lean premixed combustion is yet also prone to combustion instabilities, resulting in thermo-acoustically induced acoustic pressure oscillations (pulsations). Understanding pulsation behavior over an enginés lifetime is of interest to accurately monitor the engine status, as wear and degradation typically affect combustion behavior and result in changes of both pulsations and emissions. Such improved understanding can be exploited for optimizing both the engine operation concept and the design of relevant hardware parts. In return, pulsation and hardware optimization may lead to reduced degradation and thus inherently more robust long-term operational behavior. The study presented here is conducted for one specific gas turbine of GE’s GT24/GT26 fleet with sequential annular combustion. Based on operational data of the examined gas turbine, a semi-empirical modeling approach is introduced to describe the pulsations measured in the first (EV) combustion chamber. The target is to reproduce measured pulsation amplitudes as well as their different behaviors with engine load. The modeling presented here has been focused on pulsations in a distinctive frequency range below 1kHz. A model based on a small set of data obtained from initial commissioning is able to represent the pulsation behavior within a normalized root mean square error of 11%. Validation with long-term engine data shows that predicted pulsation levels are reasonably matching the initial operation period but increasingly deviate with engine operating time. By using additional data from later engine commissioning and adjustments, the robustness of the model is sensibly increased. Model accuracy on the training dataset remains similar at around 11%, but validation on the long-term data shows a significant decrease of the normalized root mean square error from over 21% to below 16%. Additional model improvements to further reduce prediction errors on long-term data have been also identified.

Development of a Dry Low NOx Combustor for 2MW Class Gas Turbine

1996 ◽  
Author(s):  
J. Hosoi ◽  
T. Watanabe ◽  
H. Toh ◽  
M. Mori ◽  
H. Sato ◽  
...  
Keyword(s):  
Control System ◽  
Gas Turbine ◽  
Film Cooling ◽  
Combustion Efficiency ◽  
Premixed Combustion ◽  
Lean Premixed Combustion ◽  
Wide Region ◽  
Lean Premixed

Development of a dry low NOx combustor for 2MW class gas turbine is described, which has been co-conducted by Ishikawajima-Harima Heavy Industries Co., Ltd. and Tokyo Gas Co., Ltd. from 1994. This combustor is characterized by three stage, lean premixed combustion with coaxial burners operated by simple control system and non-film cooling, from which low NOx and high combustion efficiency within the wide region of load can be obtained. Component rig tests indicated NOx ≒10ppm (at 16% O2), combustion efficiency η c >99.8% could be obtained over load more than 50%.

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