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.

Investigation on Flowfield and Fuel/Air Premixing Uniformities of Low Swirl Injector for Lean Premixed Gas Turbines

2021 ◽  
Author(s):  
Fujun Sun ◽  
Jianqin Suo ◽  
Zhenxia Liu
Keyword(s):  
Penetration Depth ◽  
Residence Time ◽  
Gas Turbines ◽  
Structural Parameters ◽  
Combustible Mixture ◽  
Operating Conditions ◽  
Flame Stability ◽  
Nox Emissions ◽  
Auto Ignition ◽  
Lean Premixed

Abstract Based on the development trend of incorporating fuel holes into swirler-vanes and the advantages of wide operating conditions as well as low NOx emissions of LSI, this paper proposes an original lean premixed LSI with a convergent outlet. The influence of key structures on flowfields and fuel/air premixing uniformities of LSI is investigated by the combination of laser diagnostic experiments and numerical simulations. The flowfields of LSI shows that the main recirculation zone is detached from the convergent outlet and its axial dimensions are smaller than that of HSI, which can decrease the residence time of high-temperature gas to reduce NOx emissions. The fuel/air premixing characteristics show that the positions and diameters of fuel holes affect fuel/air premixing by changing the penetration depth of fuel. And when the penetration depth is moderate, it can give full play to the role of swirling air in enhancing premixing of fuel and air. In addition, the increase of the length of the premixing section can improve the uniformity of fuel/ar premixing, but it can also weaken the swirl intensity and increase the residence time of the combustible mixture within the LSI, which can affect flame stability and increase the risk of auto-ignition. Therefore, the design and selection of LSI structural parameters should comprehensively consider the requirements of fuel/air mixing uniformity, flame stability and avoiding the risk of auto-ignition. The results can provide the technical basis for LSI design and application in aero-derivative and land-based gas turbine combustors.

scholarly journals Radical Overshoot Phenomena in Liquid Fueled Gas Turbine Combustors

1977 ◽  
Author(s):  
R. Kollrack ◽  
L. D. Aceto
Keyword(s):  
Gas Turbine ◽  
Residence Time ◽  
Gas Turbines ◽  
Combustion Zone ◽  
Equivalence Ratio ◽  
Drop Size ◽  
Formation Rate ◽  
Liquid Fuels ◽  
No Production ◽  
No Formation

A detailed analysis is presented of the processes involved in the production of NO during the combustion of liquid fuels in gas turbines. With O and OH concentrations in excess of the equilibrium values the NO production rate displays a temporary overshoot within the primary combustion zone residence time. The contributions of temperature and reaction kinetics to this overshoot are assessed. This overshoot is strongly dependent on equivalence ratio and on pressure, with the minimum overshoot occurring at ϕ = 0.9. It increases more strongly for richer than for leaner combustion. Increasing drop size at lean or stoichiometric conditions tends to retard and diminish the overshoot of the NO formation rate while increasing its duration. At rich conditions, however, increasing drop size can cause overshoot increases. Changing degrees of premixedness for a given drop size, produces a timewise shifting of this overshoot. An assessment is made of the influences and interrelation of drop size distribution, degree of premixedness and staged fuel addition.

Operating Experience of the GT13E2 at Kawasaki Gas Turbine Research Center

1999 ◽  
Author(s):  
Tatsuo Fujii ◽  
Takakazu Uenaka ◽  
Hitoshi Masuo
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Gas Flow ◽  
High Reliability ◽  
Operating Experience ◽  
Operational Reliability ◽  
Nox Emission ◽  
Research Center ◽  
Major Influence ◽  
Nox Emissions

The first Kawasaki-ABB GT13E2 gas turbine began operating at Kawasaki Gas Turbine Research Center (KGRC) in Sodegaura city, Japan in January 1994. This facility is a simple-cycle power station and is operated in DSS (Daily Start and Stop) operation mode as a peaking unit, and its output electricity is delivered to Tokyo Electric Power Company (TEPCO). The GT13E2 gas turbine at KGRC was manufactured jointly by Kawasaki Heavy Industries (KHI) and Asea Brown Boveri (ABB). KHI and ABB have a joint test program with this facility to research for high reliability, high performance and low emission for the GT13E2 and future gas turbines. The performance of the KGRC GT13E2 has been monitored continuously. It was found from these monitored data that the thermal efficiency has been maintained at a high level and could be recovered by compressor washing when the compressor was fouled. Several factors which influence NOx emissions were studied on the gas turbine, and it was found that atmospheric humidity has a major influence on NOx emissions. Also other factor such as the position of the variable inlet guide vanes (VIGV) and fuel gas flow through each burner of the combustor were adjusted to reduce NOx emission. As a result, NOx emission from the KGRC GT13E2 has been maintained at a very low level. Reliability, availability and maintainability (RAM) has been evaluated by Operational Reliability Analysis Program (ORAP®) of Strategic Power Systems, Inc. (SPS) in order to identify and improve RAM performance of the GT13E2 at KGRC. These analyses made it clear what kind of outage had an impact on the reliability, availability and starting reliability of the KGRC GT13E2 and appropriate actions have increased the starting reliability. This paper describes operating experiences of the KGRC GT13E2 including performance, emissions and RAM performance.

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.

Investigation of H2/CH4-Air Flame Characteristics of a Micromix Model Burner at Atmosphere Pressure Condition

2018 ◽  
Author(s):  
Xunwei Liu ◽  
Weiwei Shao ◽  
Yong Tian ◽  
Yan Liu ◽  
Bin Yu ◽  
...  
Keyword(s):  
Hydrogen Content ◽  
Gas Turbines ◽  
Turbulent Flame ◽  
Experimental Studies ◽  
Nox Emission ◽  
Inlet Temperature ◽  
Nox Emissions ◽  
High Hydrogen ◽  
Atmosphere Pressure ◽  
Turbulent Flame Speed

For high-hydrogen-content fuel, the Micromix Combustion Technology has been developed as a potential low NOx emission solution for gas turbine combustors, especially for advanced gas turbines with high turbine inlet temperature. Compared with conventional lean premixed flames, multiple distributed slim and micro flames could lead to a lower NOx emission performance for shortening residence time of high temperature flue gas and generally a more uniform temperature distribution. This work aims at micromix flame characteristics of a model burner fueled with hydrogen blending with methane under atmosphere pressure conditions. The model burner assembly was designed to have six concentrically millimeter-sized premixed units around a same unit centrally. Numerical and experimental studies were conducted on mixing performance, flame stability, flame structure and CO/NOx emissions of the model burner. OH radical distribution by OH-PLIF and OH chemiluminescence (OH*) imaging were employed to analyze the turbulence-reaction interactions and characters of the reaction zone at the burner exit. Micromix flames fueled with five different hydrogen content H2-CH4 (60/40, 50/50, 40/60, 30/70, 0/100 Vol.%) were investigated, along with the effects of equivalence ratio and heat load. Results indicated that low NOx emissions of less than 10 ppm (@15% O2) below the exhaust temperature of 1920 K were obtained for all the different fuels. Combustion oscillation didn’t occur for all the conditions. It was found that at a constant flame temperature, the higher the hydrogen content of the fuel, the higher the turbulent flame speed and the weaker the flame lift effect. Combustion noise and NOx emissions also increase with increasing hydrogen content. The OH/OH* signal distribution indicated that a pure methane micromix flame showed a lifted and weaken distributed feature.

scholarly journals Variations in the NOx Emission of Gas Turbines: Effects of Air Temperature, Air Humidity and Natural Gas Composition

1994 ◽  
Author(s):  
B. Martien Visser ◽  
Fred C. Bahlmann
Keyword(s):  
Gas Turbines ◽  
Flame Temperature ◽  
Calorific Value ◽  
Nox Emission ◽  
Nox Emissions ◽  
Gas Composition ◽  
Air Humidity ◽  
Ambient Conditions ◽  
Fuel Gas ◽  
Natural Gases

The NOx emission, produced by gas turbines varies with ambient conditions and with fuel gas composition. Often, legislation requires that the NOx emissions of gas turbines has to be corrected to standard conditions. The EPA formula may be used for the correction for ambient temperature and humidity. In the Netherlands, the correction for fuel-gas composition is based on the observation that for natural gases, NOx emission varies linearly with the Lower Calorific Value (LCV). It is concluded that both the EPA and LCV correction formulas are equivalent to the following relation between flame temperature and NOx emission: NOxa=NOxb*(1.0065)Ta−Tb where Ta and Tb represent characteristic flame temperatures under conditions a and b. In the paper, the utility of the EPA and the LCV correction formulas for gas turbines equipped with modem lean-premixed combustors is discussed.

Testing of a Hydrogen Dilute Diffusion Array Injector at Gas Turbine Conditions

2011 ◽  
Author(s):  
Nathan T. Weiland ◽  
Todd G. Sidwell ◽  
Peter A. Strakey
Keyword(s):  
Pressure Drop ◽  
Gas Turbine ◽  
Residence Time ◽  
Firing Temperature ◽  
Gas Turbines ◽  
Advanced Technology ◽  
Nox Emissions ◽  
High Hydrogen ◽  
Air Jet ◽  
Nitrogen Dilution

The U.S. Department of Energy’s Turbines Program is developing advanced technology for high-hydrogen gas turbines to enable integration of carbon sequestration technology into coal-gasifying power plants. Program goals include aggressive reductions in gas turbine NOx emissions: less than 2 ppmv NOx at 15% oxygen and 1750 K firing temperature. The approach explored in this work involves nitrogen dilution of hydrogen diffusion flames, which avoids problems with premixing hydrogen at gas turbine pressures and temperatures. Thermal NOx emissions are partially reduced through peak flame temperature control provided by nitrogen dilution, while further reductions are attained by minimizing flame size and residence time. The injector design includes high-velocity coaxial air injection from lobes surrounding the central fuel tube in each of the 48 array units. This configuration strikes a balance between stability and ignition performance, combustor pressure drop, and flame residence time. Array injector test conditions in the optically accessible Low Emissions Combustor Test & Research (LECTR) facility include air preheat temperatures of 500 K, combustor pressures of 4, 8 and 16 atm, equivalence ratios of 0.3 to 0.7, and three hydrogen/nitrogen fuel blend ratios. Test results show that NOx emissions increase with pressure and decrease with increasing fuel and air jet velocities, as expected. The magnitude of these emissions changes deviate from expected NOx scaling relationships, however, due to active combustor cooling and array spacing effects. At 16 atm and 1750 K firing temperature, the lowest NOx emissions obtained is 4.4 ppmv at 15% O2 equivalent (3.0 ppmv if diluent nitrogen is not considered), with a corresponding pressure drop of 7.7%. While these results demonstrate that nitrogen dilution in combination with high strain rates provides a reliable solution to low NOx hydrogen combustion at gas turbine conditions, the injector’s performance can still be improved significantly through suggested design changes.

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.

scholarly journals Uncertainty in Gas Turbine NOx Emission Measurements

1998 ◽  
Author(s):  
Wilfred S. Y. Hung ◽  
Alan Campbell
Keyword(s):  
Measurement Uncertainty ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Water Injection ◽  
Nox Emission ◽  
Regulatory Agencies ◽  
Nox Emissions ◽  
Current State ◽  
Combustion Systems ◽  
Good Agreement

The advent of dry, low-emissions combustion systems for gas turbine applications and the trend towards requiring emissions monitoring and lower NOx limits by regulatory agencies, have created renewed interests in the uncertainty of NOx emissions measurements. This paper addresses the uncertainty of measuring NOx emissions from gas turbines in the field, including gas turbines equipped with conventional combustion systems, with or without water injection, with dry, low-emissions combustion systems and with exhaust clean-up systems. The sources of errors, using current state-of-the-art instruments, in field emissions testing or continuous emission monitoring of gas turbines to meet specific emission (ppmvd @ 15% O2) as well as mass emission rate (kg/hr) limits are identified. The uncertainty of measuring NOx emissions from gas turbines is estimated and compared with Geld data. The effect of NOx emission levels on measurement uncertainty is also addressed. The minimus NOx measurement uncertainty is determined and is in good agreement with what is currently allowed by regulatory agencies.

PEMS: Monitoring NOx Emissions From Gas Turbines

1995 ◽  
Author(s):  
Wilfred S. Y. Hung ◽  
Fritz Langenbacher
Keyword(s):  
Monitoring System ◽  
Gas Turbines ◽  
High Reliability ◽  
Ambient Air ◽  
Nox Emission ◽  
Federal State ◽  
Nox Emissions ◽  
Emission Model ◽  
Report Generation ◽  
Emission Monitoring

Predictive Emission Monitoring System (PEMS) was developed in 1990 to provide continuous monitoring of NOx emissions from stationary gas turbines with minimum maintenance. This system will meet the Enhanced Monitoring requirements under Title V of the Clean Air Act Amendments of 1990 when these requirements are finalized. The PEMS has been well received by various United States federal, state and local environmental agencies. It has been certified in the state of Colorado, and accepted in Pennsylvania and Texas. This paper reviews the Enhanced Monitoring requirements for gas turbine NOx emissions monitoring and discusses the technical background of the PEMS. The PEMS design is described, including inputs, outputs and operator interface. Experiences with some of the installed systems are presented. The PEMS predicts NOx emissions from turbine control system inputs and measurements of ambient air conditions. The prediction algorithms are based upon a time tested NOx emission model for gas turbines. This model has successfully predicted all measured NOx emission phenomena from gas turbines since 1974. The PEMS has been proven to be accurate within the 20% relative accuracy required for certification. The PEMS operates unattended, with extremely low maintenance and high reliability. Record keeping and report generation are automated. The PEMS is typically integrated into the turbine control and condition monitoring system. The PEMS meets regulatory requirements with a much lower cost than a conventional Continuous Emission Monitoring System (CEMS).

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