scholarly journals Semi–Empirical Correlation of NOx Emissions From Combustion Turbines With Water/Steam Injection

1995 ◽  
Author(s):  
Donald M. Newburry ◽  
Arthur M. Mellor
Keyword(s):  
Standard Deviation ◽  
Formation Rate ◽  
Flame Temperature ◽  
Steam Injection ◽  
Measured Data ◽  
Fuel Oil ◽  
Nox Emissions ◽  
Time Model ◽  
Water Steam ◽  
Semi Empirical

Inert (water or steam) injection is commonly used to reduce NOx emissions in stationary gas turbine combustors, both lean premixed when oil–fired and conventional. Thus, having an accurate phenomenological model to predict these reductions could be useful in both design and implementation for low emissions. In this work, the semi–empirical characteristic time model (CTM), which has been validated for thermal NOx emissions from conventional, diffusion flame combustors, is modified to account for inert injection effects. Measured NOx data from two heavy–duty, utility combustion turbines operating on natural gas and fuel oil #2, both dry and with water or steam injection, are correlated. Inert injection is modeled as thermal, and two limiting cases are proposed which successfully bound the measured data. An empirically selected effective inert injection flame temperature was substituted for the stoichiometric flame temperature used to estimate the thermal NO formation rate in the CTM. This procedure correlated all of the measured data from both combustors for both fuels with a standard deviation of 1.02 g NO2/kg fuel. The high standard deviation results from systematic trends in the dry data for one combustor which propagate through the lower NOx values of the inert injection data. Removing these trends empirically improves the combined correlation to a standard deviation of 0.28 g/kg (approximately 3.2 ppmvd at 15% O2).

Semi–Empirical Predictions and Correlations of NOx Emissions From Utility Combustion Turbines

1995 ◽  
Author(s):  
Donald M. Newburry ◽  
Arthur M. Mellor
Keyword(s):  
Natural Gas ◽  
A Priori ◽  
Fuel Oil ◽  
Pollutant Emissions ◽  
Nox Emissions ◽  
Time Model ◽  
Heterogeneous Effects ◽  
Inlet Conditions ◽  
Thermal Nox ◽  
Semi Empirical

Semi–empirical equations model the dominant subprocesses involved in pollutant emissions by assigning specific times to the fuel evaporation, chemistry, and turbulent mixing. They then employ linear ratios of these times with model constants established by correlating data from combustors with different geometries, inlet conditions, fuels, and fuel injectors to make a priori predictions. In this work, thermal NOx emissions from two heavy–duty, dual fuel (natural gas and fuel oil #2) diffusion flame combustors designated A and B operating without inert injection are first predicted, and then correlated using three existing semi–empirical approaches termed the Lefebvre (AHL) model, the Rizk–Mongia (RM) model, and the characteristic time model (CTM). Heterogeneous effects were found to be significant, as fuel droplet evaporation times were required to align the natural gas and fuel oil data. Only the RM model and CTM were employed to study this phenomenon. The CTM achieved the best overall prediction and correlation, as the data from both combustors fell within one standard deviation of the predicted line. The AHL and RM models were not able to account for the geometries of the two combustors. For Combustor A the CTM parameter correlated the data in a highly linear manner, as expected, but for Combustor B there was significant curvature. Using the CTM this was shown to be a residence time effect.

Water/Steam Injection for NOx Reduction in Process Burners

2018 ◽  
Author(s):  
Steve Londerville ◽  
Kevin Anderson ◽  
Charles Baukal ◽  
Wes Bussman
Keyword(s):  
Gas Turbines ◽  
Nox Reduction ◽  
Flame Temperature ◽  
Steam Injection ◽  
Water Steam ◽  
Flame Instability ◽  
Wide Range ◽  
Unburned Hydrocarbons ◽  
Thermal Nox ◽  
Flame Chemistry

Liquid water or steam injection is a technique that has been used for years to reduce NOx primarily by reducing the flame temperature which reduces thermal NOx. There is also evidence to suggest it reduces NOx by modifying the flame chemistry. While it is well proven for reducing NOx, there are some potential disadvantages including reduced thermal efficiency, flame instability, and increased emissions of other pollutants such as CO and unburned hydrocarbons. Water/steam injection has been used in a wide range of applications, particularly in boilers and gas turbines. Much less information is available on using this technique in process heaters which have some key differences compared to most combustors which include a highly varying fuel composition and natural draft to provide the combustion air. This paper will consider how water or steam may be injected into process burners including some predictive methods for determining NOx.

Technology Update on Gas Turbine Dual Fuel, Dry Low Emission Combustion Systems

2003 ◽  
Author(s):  
Petter Egil Ro̸kke ◽  
Johan E. Hustad ◽  
Nils A. Ro̸kke ◽  
Ole Birger Svendsgaard
Keyword(s):  
Gas Turbine ◽  
Flame Temperature ◽  
Steam Injection ◽  
Dual Fuel ◽  
Combustion System ◽  
Single Digit ◽  
Water Steam ◽  
Marine Propulsion ◽  
Low Emission ◽  
Combustion Systems

A challenging issue in the gas turbine industry is to develop a practical dual fuel (DF), dry low emission (DLE) combustion system. Especially for the onshore-based power generation systems, and liquid DLE for aeroderivative engines used for marine propulsion. A novel mid-size (3MW) gas turbine is being developed mainly targeted for marine propulsion, where a dual fuel DLE combustion system aiming at single digit NOx emission figures has been explored. As a part of this development, the present technology available from different gas turbine manufacturers has been surveyed. Status of the different techniques applied in dual fuel DLE combustors today and their achievements are presented, including the available information on fuel injectors, cooling schemes, combustion air distribution, noise control and combustor performance. The techniques utilized and explained are such as flame temperature control (water/steam injection), staged combustion, lean premixing and lean prevaporized premixing, rich-quench-lean-burning (RQLB) and catalytic combustion. These are also documented for the different concepts commercially available, describing both advantages and drawbacks. Conclusions are made towards the dominating trends for the different parameters mentioned above, and how they affect the final combustor design. A survey of the dominating parameters for low emission combustion systems is presented.

Hydrogen-Enriched Methane Combustion Diluted With Exhaust Gas and Steam: Fundamental Investigation on Laminar Flames and NOx Emissions

2017 ◽  
Author(s):  
Charles Lhuillier ◽  
Romain Oddos ◽  
Lisa Zander ◽  
Finn Lückoff ◽  
Katharina Göckeler ◽  
...  
Keyword(s):  
Power Plants ◽  
Numerical Study ◽  
Flame Temperature ◽  
Methane Combustion ◽  
Steam Injection ◽  
High Reactivity ◽  
Stable Operation ◽  
Nox Emissions ◽  
Exhaust Gas ◽  
Nox Formation

Hydrogen utilization in conventional power plants can offer a possibility to cover the residual load of volatile renewable energies while at the same time reducing the carbon footprint of power production. The challenge here is the high reactivity of hydrogen posing a risk of flashback, whereas increased flame temperature may result in higher NOx emissions. A promising approach to overcome this challenges is the dilution of combustion mixtures by exhaust gas recirculation or by steam injection. The present paper provides experimental laminar burning velocities of hydrogen-enriched methane/air mixtures diluted with major components of exhaust gas and with steam. The corresponding numerical study based on a fictive species approach is used to quantify the chemical and physical effects of dilution on laminar burning velocities. The influence of hydrogen-enrichment and dilution on NOx formation is studied numerically. The results demonstrate high potential of dilution with steam or exhaust gas to ensure stable operation even for hydrogen-rich mixtures while maintaining low NOx emissions.

scholarly journals A Fuel Oilpremix Burner for Gas Turbines: Development and Initial Operating Experience

1994 ◽  
Author(s):  
Bernhard Schetter ◽  
Hans Wilhelm Schabbehard ◽  
Ulf Josefson ◽  
Anders Ahlberg
Keyword(s):  
Power Plant ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Operating Experience ◽  
Steam Injection ◽  
Fuel Oil ◽  
Nox Emissions ◽  
Premix Combustion ◽  
Additional Water ◽  
Fruitful Cooperation

Premix combustion of natural gas in Siemens hybrid burners has been carried out successfully in gas turbine power plant since 1986 and has enabled NOx emissions below 10 ppm to be achieved without additional water or steam injection. Based on this experience, the hybrid burner has been further developed for the premix combustion of fuel oil and is now in commercial operation in a Siemens Model V94.2 gas turbine at the Halmstad power plant in Sweden. The final testing of the new burners on site was carried out from January to September 1993 by courtesy of and in a fruitful cooperation with the client, SYDKRAFT AB. This paper sets out a number of requirements for successful premix combustion of fuel oil, describes how these requirements have been met and concludes with the results of site measurements of NOx and CO emissions. Base load NOx emissions were reduced to less than a quarter of their previous values without additional water or steam injection.

scholarly journals Testing the star formation scaling relations in the clumps of the North American and Pelican nebulae cloud complex

2020 ◽  
Vol 500 (3) ◽  
pp. 3123-3141
Author(s):  
Swagat R Das ◽  
Jessy Jose ◽  
Manash R Samal ◽  
Shaobo Zhang ◽  
Neelam Panwar
Keyword(s):  
Star Formation ◽  
Surface Density ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Free Fall ◽  
Scaling Relations ◽  
Time Model ◽  
Fall Time ◽  
The North ◽  
Crossing Time

ABSTRACT The processes that regulate star formation within molecular clouds are still not well understood. Various star formation scaling relations have been proposed as an explanation, one of which is to formulate a relation between the star formation rate surface density $\rm \Sigma _{SFR}$ and the underlying gas surface density $\rm \Sigma _{gas}$. In this work, we test various star formation scaling relations, such as the Kennicutt–Schmidt relation, the volumetric star formation relation, the orbital time model, the crossing time model and the multi free-fall time-scale model, towards the North American Nebula and Pelican Nebula and in the cold clumps associated with them. Measuring stellar mass from young stellar objects and gaseous mass from CO measurements, we estimate the mean $\rm \Sigma _{SFR}$, the star formation rate per free-fall time and the star formation efficiency for clumps to be 1.5 $\rm M_{\odot}\, yr^{-1}\, kpc^{-2}$, 0.009 and 2.0 per cent, respectively, while for the whole region covered by both nebulae (which we call the ‘NAN’ complex) the values are 0.6 $\rm M_{\odot}\, yr^{-1}\, kpc^{-2}$, 0.0003 and 1.6 per cent, respectively. For the clumps, we notice that the observed properties are in line with the correlation obtained between $\rm \Sigma _{SFR}$ and $\rm \Sigma _{gas}$, and between $\rm \Sigma _{SFR}$ and $\rm \Sigma _{gas}$ per free-fall time and orbital time for Galactic clouds. At the same time, we do not observe any correlation with $\rm \Sigma _{gas}$ per crossing time and multi free-fall time. Even though we see correlations in the former cases, however, all models agree with each other within a factor of 0.5 dex. It is not possible to discriminate between these models because of the current uncertainties in the input observables. We also test the variation of $\rm \Sigma _{SFR}$ with the dense gas but, because of low statistics, a weak correlation is seen in our analysis.

Detection and Analysis of Rats’ Bioelectromagnetic Signal

2014 ◽  
Vol 536-537 ◽  
pp. 13-17
Author(s):  
Hong Long Cao ◽  
Fen Ju Qin ◽  
Xue Guan Liu ◽  
He Ming Zhao
Keyword(s):  
Standard Deviation ◽  
Automatic System ◽  
Measurement Method ◽  
Measurement Accuracy ◽  
Biological Activities ◽  
Measurement Data ◽  
Measured Data ◽  
The Mean ◽  
Frequency Window ◽  
Window Effects

In this paper, we designed an automatic system and automatic test software, and they can carry out Kunming rats bioelectromagnetic measurement in standard status and anesthesia automatically in anechoic chamber where the electromagnetic field outside is shielded, the reflection wave is absorbed, and the measurement accuracy will be improved. We get a great number of measurement data with frequency-sweep measurement method. The mean and standard deviation of amplitudes vs. frequencies is calculated and analyzed. The results show the measurement method is feasible. We have plotted the means of measured data as multiple sets of Y values in a series of bars with standard deviations bars included and distributed in the frequency axis of X. It is found that the fluctuation of the mean and standard deviation in some frequencies is not evident which may explain frequency window effects, while in other frequencies, such a fluctuation can be obviously observed, which may suggest that bioelectromagnetic signal is influenced by biological activities (standard and anaesthesia status) in these frequency points.

A Critical Review of NOx Correlations for Gas Turbine Combustors

1975 ◽  
Author(s):  
D. A. Sullivan ◽  
P. A. Mas
Keyword(s):  
Experimental Data ◽  
Data Base ◽  
Gas Turbine ◽  
Critical Review ◽  
Inlet Temperature ◽  
Nox Emissions ◽  
Empirical Correlations ◽  
Gas Turbine Combustors ◽  
Semi Empirical ◽  
Adequate Data

The effect of inlet temperature, pressure, air flowrate and fuel-to-air ratio on NOx emissions from gas turbine combustors has received considerable attention in recent years. A number of semi-empirical and empirical correlations relating these variables to NOx emissions have appeared in the literature. They differ both in fundamental assumptions and in their predictions. In the present work, these simple NOx correlations are compared to each other and to experimental data. A review of existing experimental data shows that an adequate data base does not exist to evaluate properly the various NOx correlations. Recommendations are proposed to resolve this problem in the future.

Ultra-Low Emission Hydrogen/Syngas Combustion With a 1.3 MW Injector Using a Micro-Mixing Lean-Premix System

2011 ◽  
Author(s):  
Brian Hollon ◽  
Erlendur Steinthorsson ◽  
Adel Mansour ◽  
Vincent McDonell ◽  
Howard Lee
Keyword(s):  
Carbon Dioxide ◽  
Natural Gas ◽  
Flame Temperature ◽  
Fuel Mixture ◽  
Full Scale ◽  
Operating Conditions ◽  
Nox Emissions ◽  
Fuel Injector ◽  
Nitrogen Dilution ◽  
Fuel Mixtures

This paper discusses the development and testing of a full-scale micro-mixing lean-premix injector for hydrogen and syngas fuels that demonstrated ultra-low emissions and stable operation without flashback for high-hydrogen fuels at representative full-scale operating conditions. The injector was fabricated using Macrolamination technology, which is a process by which injectors are manufactured from bonded layers. The injector utilizes sixteen micro-mixing cups for effective and rapid mixing of fuel and air in a compact package. The full scale injector is rated at 1.3 MWth when operating on natural gas at 12.4 bar (180 psi) combustor pressure. The injector operated without flash back on fuel mixtures ranging from 100% natural gas to 100% hydrogen and emissions were shown to be insensitive to operating pressure. Ultra-low NOx emissions of 3 ppm were achieved at a flame temperature of 1750 K (2690 °F) using a fuel mixture containing 50% hydrogen and 50% natural gas by volume with 40% nitrogen dilution added to the fuel stream. NOx emissions of 1.5 ppm were demonstrated at a flame temperature over 1680 K (2564 °F) using the same fuel mixture with only 10% nitrogen dilution, and NOx emissions of 3.5 ppm were demonstrated at a flame temperature of 1730 K (2650 °F) with only 10% carbon dioxide dilution. Finally, using 100% hydrogen with 30% carbon dioxide dilution, 3.6 ppm NOx emissions were demonstrated at a flame temperature over 1600 K (2420 °F). Superior operability was achieved with the injector operating at temperatures below 1470 K (2186 °F) on a fuel mixture containing 87% hydrogen and 13% natural gas. The tests validated the micro-mixing fuel injector technology and the injectors show great promise for use in future gas turbine engines operating on hydrogen, syngas or other fuel mixtures of various compositions.

scholarly journals Characterization of a Novel Porous Injector for Multi-Lean Direct Injection (M-LDI) Combustor

2017 ◽  
Author(s):  
Jianing Li ◽  
Umesh Bhayaraju ◽  
San-Mou Jeng
Keyword(s):  
Air Temperature ◽  
Mass Fraction ◽  
Direct Injection ◽  
Flame Temperature ◽  
Gaseous Fuel ◽  
Nox Emissions ◽  
Fuel Injector ◽  
Porous Tube ◽  
Lean Direct Injection ◽  
Air Mixing

A generic novel injector was designed for multi-Lean Direct Injection (M-LDI) combustors. One of the drawbacks of the conventional pressure swirl and prefilming type airblast atomizers is the difficulty of obtaining a uniform symmetric spray under all operating conditions. Micro-channels are needed inside the injector for uniformly distributing the fuel. The problem of non-uniformity is magnified in smaller sized injectors. The non-uniform liquid sheet causes local fuel rich/lean zones leading to higher NOx emissions. To overcome these problems, a novel fuel injector was designed to improve the fuel delivery to the injector by using a porous stainless steel material with 30 μm porosity. The porous tube also acts as a prefilming surface. Liquid and gaseous fuels can be injected through the injector. In the present study, gaseous fuel was injected to investigate injector fuel-air mixing performance. The gaseous fuel was injected through a porous tube between two radial-radial swirling air streams to facilitate fuel-air mixing. The advantage of this injector is that it increases the contact surface area between the fuel-air at the fuel injection point. The increased contact area enhances fuel-air mixing. Fuel-air mixing and combustion studies were carried out for both gaseous and liquid fuel. Flame visualization, and emissions measurements were carried out inside the exit of the combustor. The measurements were carried out at atmospheric conditions under fuel lean conditions. Natural gas was used as a fuel in these experiments. Fuel-air mixing studies were carried out at different equivalence ratios with and without confinement. The mass fraction distributions were measured at different downstream locations from the injector exit. Flame characterization was carried out by chemiluminescence at different equivalence ratios and inlet air temperatures. Symmetry of the flame, flame length and heat release distribution were analyzed from the flame images. The effects of inlet air temperature and combustion flame temperature on emissions was studied. Emissions were corrected to 15% O2 concentration. NOx emissions increase with inlet air temperature and flame temperature. Effect of flame temperature on NOx concentration is more significant than effect of inlet air temperature. Fuel-air mixing profile was used to obtain mass fraction Probability Density Function (pdf). The pdfs were used for simulations in Chemkin Pro. The measured emissions concentrations at the exit of the injector was compared with simulations. In Chemkin model, a network model with several PSRs (perfectly stirred reactor) were utilized, followed by a mixer and a PFR (plug flow reactor). The comparison between the simulations and the experimental results was investigated.

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