Nonequilibrium Effect on Nitrogen Oxides Production in a Diffusion Flame

2012 ◽  
Author(s):  
V. V. Tsatiashvili ◽  
V. G. Avgustinovich
Keyword(s):  
Gas Turbines ◽  
Fuel Injection ◽  
Nox Emission ◽  
Maximum Effect ◽  
Diffusion Combustion ◽  
No Production ◽  
Mixing Rate ◽  
Production Scale ◽  
Emission Level ◽  
Reduction Of Nox

Reduction of NOx emission of aircraft gas turbines is moving in the direction of development of direct combustor fuel injection systems providing conditions for rapid mixing and combustion of a uniform lean fuel/air mixture. However, formation of sufficient uniform fuel/air mixture in real combustors fails to be completed. It may result in burning out a considerable portion of fuel in stoichiometric conditions that in turn imposes limits on the emission level minimizing. The research accomplished by a number of authors justifies the necessity of decreasing the extent of stoichiometric zones by means of increasing fuel-air mixing rate on the stoichiometric surface of their contact, to reduce emission. This publication contains the analysis results upon the effect of mixing rate, in terms of a methane-air laminar diffusion combustion. It is proved that changes of mixing rate influence the two main factors governing the emission level: the extent of NO production zone and the efficient rate of its production. If the mixing rate increases explicitly due to the decrease of NOx production scale, the efficient velocity curve will contain a maximum value. Furthermore, the scale effect is all-over stronger than the kinetic one. It is concluded that in case of mixing rate increase, the reduction of NOx emission goes nonlinearly and steadily. The ranges of maximum effect are specified. Herewith, we introduce the relation, which demonstrates that in the diffusion combustion a sufficient reduction of NOx emission can be achieved.

Emission Characteristics of NO and NO2 in Rich-Lean Combustion of Hydrogen

2003 ◽  
Author(s):  
T. Shudo ◽  
K. Omori ◽  
O. Hiyama
Keyword(s):  
Gas Turbines ◽  
Nox Reduction ◽  
Hydrogen Combustion ◽  
Hydrocarbon Fuels ◽  
Nox Emission ◽  
Diffusion Combustion ◽  
Lean Combustion ◽  
Hydrocarbon Combustion ◽  
The Rich ◽  
Reduction Effect

Hydrogen is expected as a clean and renewable alternative to the conventional hydrocarbon fuels. Because the only possible pollutants from the hydrogen combustion are nitrogen oxides (NOx), it is crucial to reduce the NOx emission in the hydrogen utilization. The rich-lean combustion is well known as a technique to reduce the emission of the Zel’dovich NO from the continuous combustion burners for such as gas turbines and boilers. Because the Zel’dovich NO occupies a large part of the total NOx emission, the rich-lean combustion is quite effective to reduce the NOx emission. However, the NOx reduction effect of the rich-lean combustion has not yet been proven for the hydrogen fuel, while the effect has been demonstrated for the hydrocarbon fuels. On the other hand, the prompt NO is emitted from the hydrocarbon combustion especially under the fuel-rich conditions. Though the amount of the prompt NO is quite small for premixed or diffusion combustion, it could be a relatively significant part in the total NO emission from the rich-lean combustion due to the decreased Zel’dovich NO. The authors estimate that hydrogen is more suitable for the rich-lean combustion compared with hydrocarbons, because hydrogen does not emit the prompt NO even under the fuel-rich conditions which necessarily exist in the rich-lean combustion. This research proposes the rich-lean combustion as a method to reduce the NOx emission from hydrogen combustion and experimentally analyzes the characteristics using a coaxial rich-lean burner with varying the mixture conditions.

SUPPRESSION OF HIGH FREQUENCY MODES OF UNSTABLE COMBUSTION IN LOW-EMISSION COMBUSTORS OF INDUSTRIAL GAS TURBINES

2020 ◽  
Author(s):  
A. N. Dubovitsky ◽  
◽  
E. D. Sverdlov ◽  
K. S. Pyankov ◽  
H. F. Valiev ◽  
...  
Keyword(s):  
High Frequency ◽  
Gas Turbines ◽  
Combustion Instability ◽  
Nox Emission ◽  
Mixed Fuel ◽  
Emission Level ◽  
Instability Modes ◽  
Low Emission ◽  
Industrial Gas Turbines ◽  
Unstable Combustion

To reduce the NOx emission level in low emission combustors designed for industrial gas turbines, the technology of lean preliminary mixed fuel-air mixtures burning is used. But this gives rise to combustion instability modes.

Low NOx Emission Technology for the Vx4.3A Gas Turbine Series in Fuel Oil Operation

2002 ◽  
Author(s):  
Juergen Meisl ◽  
Gerald Lauer ◽  
Stefan Hoffmann
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Nox Emission ◽  
Fuel Oil ◽  
Liquid Fuels ◽  
Nox Emissions ◽  
Premix Combustion ◽  
Reduction Of Nox ◽  
Low Nox Emission ◽  
Distillate Fuel

This contribution describes the systematic refinement of the hybrid burner used in Siemens Vx4.3A gas turbines for lean premix combustion of various liquid fuels such as Distillate fuel No. 2, Naphtha and Condensate. Additionally to the dry premix operation fuel/water emulsions are used in premix mode for a further reduction of NOx emissions or power augmentation. NOx emissions of less than 72 ppm are already achieved with the HR3 hybrid burner in dry premix mode. These can be reduced to values below of 42 ppm NOx in emulsion mode.

The Effects of Water, Pressure, and Equivalence Ratio on Nitric Oxide Production in Gas Turbines

1974 ◽  
Vol 96 (3) ◽  
pp. 240-246 ◽  
Author(s):  
H. Shaw
Keyword(s):  
Nitric Oxide ◽  
Residence Time ◽  
Gas Turbines ◽  
Fluid Dynamic ◽  
Water Pressure ◽  
Nox Emission ◽  
No Production ◽  
Nox Emissions ◽  
Emission Index ◽  
Equilibrium Calculations

A semiempirical technique for predicting the NOx emission index from the combustion of distillate type fuels with air was developed. This technique was devised to help evaluate combustion modification procedures for lowering NOx emissions. Equilibrium calculations, generally used to obtain directional estimates of pollutant concentration, can lead to errors. Some possible pitfalls in using equilibrium calculations are illustrated. The semiempirical technique is based on chemical kinetics and neglects fluid-dynamic effects. The kinetics are based on the modified Zeldovich chain mechanism for NO production from hot air and Fenimore’s data for “prompt NOx”. The resulting expression lends itself to hand calculation provided the nitric oxide equilibrium value is known at the temperature and pressure of interest. Excellent agreement was obtained with experimental results from gas turbines. The apparent time required to produce NOx was the only adjustable parameter used to fit the data. A large volume of data from aircraft gas turbines was correlated by assuming an apparent residence time of 0.5 millisec. The effectiveness of water addition in minimizing NOx emissions was predicted for a model of an industrial gas turbine using 2 millisec residence time. These residence times are somewhat short but physically reasonable. The calculations predict that the maximum NOx emission index shifts from stoichiometric combustion to lean combustion as air preheat temperature is lowered. This prediction has not been confirmed experimentally.

Reduction of NOx Emission of Heavy Duty Gas Turbines by Improving Mixing Quality Using CFD Tools

2003 ◽  
Author(s):  
Weiqun Geng ◽  
Douglas Pennell ◽  
Stefano Bernero ◽  
Peter Flohr
Keyword(s):  
Gas Turbines ◽  
Mass Fraction ◽  
Cross Flow ◽  
Nox Emission ◽  
Injection System ◽  
Water Tunnel ◽  
Injection Hole ◽  
Fuel Mass ◽  
Mixing Quality ◽  
Fuel Mass Fraction

Jets in cross flow are one of the fundamental issues for mixing studies. As a first step in this paper, a generic geometry of a jet in cross flow was simulated to validate the CFD (Computational Fluid Dynamics) tool. Instead of resolving the whole injection system, the effective cross-sectional area of the injection hole was modeled as an inlet surface directly. This significantly improved the agreement between the CFD and experimental results. In a second step, the calculated mixing in an ALSTOM EV burner is shown for varying injection hole patterns and momentum flux ratios of the jet. Evaluation of the mixing quality was facilitated by defining unmixedness as a global non-dimensional parameter. A comparison of ten cases was made at the burner exit and on the flame front. Measures increasing jet penetration improved the mixing. In the water tunnel the fuel mass fraction within the burner and in the combustor was measured across five axial planes using LIF (Laser Induced Fluorescence). The promising hole patterns chosen from the CFD computations also showed a better mixing in the water tunnel than the other. Distribution of fuel mass fraction and unmixedness were compared between the CFD and LIF results. A good agreement was achieved. In a final step the best configuration in terms of mixing was checked with combustion. In an atmospheric test rig measured NOx emissions confirmed the CFD prediction as well. The most promising case has about 40% less NOx emission than the base case.

Influencing factors on NOX emission level during grate conversion of three pelletized energy crops

2014 ◽  
Vol 115 ◽  
pp. 360-373 ◽  
Author(s):  
Maryori Díaz-Ramírez ◽  
Fernando Sebastián ◽  
Javier Royo ◽  
Adeline Rezeau
Keyword(s):  
Influencing Factors ◽  
Energy Crops ◽  
Nox Emission ◽  
Emission Level

scholarly journals Numerical study of flame structure in the mild combustion regime

2015 ◽  
Vol 19 (1) ◽  
pp. 21-34 ◽  
Author(s):  
Amir Mardani ◽  
Sadegh Tabejamaat
Keyword(s):  
Fuel Injection ◽  
Numerical Study ◽  
Flame Structure ◽  
Combustion Regime ◽  
Low Oxygen ◽  
Mixing Rate ◽  
Jet Flame ◽  
Reduced Mechanism ◽  
Mild Combustion ◽  
O2 Concentration

In this paper, turbulent non-premixed CH4+H2 jet flame issuing into a hot and diluted co-flow air is studied numerically. This flame is under condition of the moderate or intense low-oxygen dilution (MILD) combustion regime and related to published experimental data. The modelling is carried out using the EDC model to describe turbulence-chemistry interaction. The DRM-22 reduced mechanism and the GRI2.11 full mechanism are used to represent the chemical reactions of H2/methane jet flame. The flame structure for various O2 levels and jet Reynolds numbers are investigated. The results show that the flame entrainment increases by a decrease in O2 concentration at air side or jet Reynolds number. Local extinction is seen in the upstream and close to the fuel injection nozzle at the shear layer. It leads to the higher flame entertainment in MILD regime. The turbulence kinetic energy decay at centre line of jet decreases by an increase in O2 concentration at hot Co-flow. Also, increase in jet Reynolds or O2 level increases the mixing rate and rate of reactions.

Development of the DLE Combustor for L30A Gas Turbine

2015 ◽  
Author(s):  
Toshiaki Sakurazawa ◽  
Takeo Oda ◽  
Satoshi Takami ◽  
Atsushi Okuto ◽  
Yasuhiro Kinoshita
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Nox Emission ◽  
Test Facility ◽  
Exhaust Temperature ◽  
Main Burner ◽  
Harmful Emissions ◽  
Emission Regulation ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Analyses

This paper describes the development of the Dry Low Emission (DLE) combustor for L30A gas turbine. Kawasaki Heavy Industries, LTD (KHI) has been producing relatively small-size gas turbines (25kW to 30MW class). L30A gas turbine, which has a rated output of 30MW, achieved the thermal efficiency of more than 40%. Most continuous operation models use DLE combustion systems to reduce the harmful emissions and to meet the emission regulation or self-imposed restrictions. KHI’s DLE combustors consist of three burners, a diffusion pilot burner, a lean premix main burner, and supplemental burners. KHI’s proven DLE technologies are also adapted to the L30A combustor design. The development of L30 combustor is divided in four main steps. In the first step, Computational Fluid Dynamics (CFD) analyses were carried out to optimize the detail configuration of the combustor. In a second step, an experimental evaluation using single-can-combustor was conducted in-house intermediate-pressure test facility to evaluate the performances such as ignition, emissions, liner wall temperature, exhaust temperature distribution, and satisfactory results were obtained. In the third step, actual pressure and temperature rig tests were carried out at the Institute for Power Plant Technology, Steam and Gas Turbines (IKDG) of Aachen University, achieving NOx emission value of less than 15ppm (O2=15%). Finally, the L30A commercial validation engine was tested in an in-house test facility, NOx emission is achieved less than 15ppm (O2=15%) between 50% and 100% load operation point. L30A field validation engine have been operated from September 2012 at a chemical industries in Japan.

A Study of the NOx Emission in a Regenerative Industrial Furnace

2001 ◽  
Author(s):  
Qing Jiang ◽  
Chao Zhang
Keyword(s):  
Mixture Fraction ◽  
Combustion Process ◽  
Nox Emission ◽  
Moment Closure ◽  
Combustion Model ◽  
Industrial Furnace ◽  
Low Emission ◽  
Reduction Of Nox ◽  
Closure Method ◽  
Probability Density Function Pdf

Abstract A study of the nitrogen oxides (NOx) emission and combustion process in a gas-fired regenerative, high temperature, low emission industrial furnace has been carried out numerically. The effect of two additives, methanol (CH3OH) and hydrogen peroxide (H2O2), to fuel on the NOx emission has been studied. A moment closure method with the assumed β probability density function (PDF) for mixture fraction is used in the present work to model the turbulent non-premixed combustion process in the furnace. The combustion model is based on the assumption of instantaneous full chemical equilibrium. The results showed that CH3OH is effective in the reduction of NOx in a regenerative industrial furnace. However, H2O2 has no significant effect on the NOx emission.

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):  
Gas Turbine ◽  
Distribution System ◽  
Gas Turbines ◽  
Liquid Fuel ◽  
Fuel Injection ◽  
Liquid Fuels ◽  
Dual Fuel ◽  
Gaseous Fuels ◽  
Supply And Distribution ◽  
Industrial Gas Turbines

Abstract Industrial gas turbines like the MGT6000 are often operated as power supply or as mechanical drives. 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 capable of ultra-low NOx emissions for gaseous fuels. This system has been further developed to provide dry dual fuel capability. 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. The pilot stage is continuously operated, whereas the bulk of the liquid fuel is injected through the premixed combustor stage. The premixed stage comprises a set of four decentralized nozzles based on fluidic oscillator atomizers, wherein atomization of the liquid fuel is achieved through self-induced oscillations. We present results illustrating the spray, hydrodynamic, and emission performance of the injectors. Extensive testing of the burner at atmospheric and full load high-pressure conditions has been performed, before verification within full engine tests. We show the design of the fuel supply and distribution system. Finally, we discuss the integration of the dual fuel system into the standard gas turbine package of the MGT6000.

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