Effects of adiabatic flame temperature on flames’ characteristics in a gas-turbine combustor

Energy ◽  
2022 ◽  
pp. 123077
Author(s):  
Mansur Aliyu ◽  
Ahmed Abdelhafez ◽  
Medhat A. Nemitallah ◽  
Syed A.M. Said ◽  
Mohamed A. Habib
Keyword(s):  
Gas Turbine ◽  
Flame Temperature ◽  
Gas Turbine Combustor ◽  
Adiabatic Flame Temperature

System Evaluation and LBTU Fuel Combustion Studies for IGCC Power Generation

1995 ◽  
Vol 117 (4) ◽  
pp. 673-677 ◽  
Author(s):  
C. S. Cook ◽  
J. C. Corman ◽  
D. M. Todd
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Coal Gasification ◽  
Flame Temperature ◽  
Combined Cycle ◽  
Gas Turbine Combustor ◽  
Gas Cleaning ◽  
Wide Range ◽  
Cycle Systems ◽  
Combined Cycles

The integration of gas turbines and combined cycle systems with advances in coal gasification and gas stream cleanup systems will result in economically viable IGCC systems. Optimization of IGCC systems for both emission levels and cost of electricity is critical to achieving this goal. A technical issue is the ability to use a wide range of coal and petroleum-based fuel gases in conventional gas turbine combustor hardware. In order to characterize the acceptability of these syngases for gas turbines, combustion studies were conducted with simulated coal gases using full-scale advanced gas turbine (7F) combustor components. It was found that NOx emissions could be correlated as a simple function of stoichiometric flame temperature for a wide range of heating values while CO emissions were shown to depend primarily on the H2 content of the fuel below heating values of 130 Btu/scf (5125 kJ/NM3) and for H2/CO ratios less than unity. The test program further demonstrated the capability of advanced can-annular combustion systems to burn fuels from air-blown gasifiers with fuel lower heating values as low as 90 Btu/scf (3548 kJ/NM3) at 2300°F (1260°C) firing temperature. In support of ongoing economic studies, numerous IGCC system evaluations have been conducted incorporating a majority of the commercial or near-commercial coal gasification systems coupled with “F” series gas turbine combined cycles. Both oxygen and air-blown configurations have been studied, in some cases with high and low-temperature gas cleaning systems. It has been shown that system studies must start with the characteristics and limitations of the gas turbine if output and operating economics are to be optimized throughout the range of ambient operating temperature and load variation.

Micromixers and Hydrogen Enrichment: The Future Combustion Technology in Zero-Emission Power Plants

2020 ◽  
Author(s):  
Muzafar Hussain ◽  
Ahmed Abdelhafez ◽  
Medhat A. Nemitallah ◽  
Mohamed A. Habib
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Power Plants ◽  
Flame Temperature ◽  
Fuel Mixture ◽  
Flame Stability ◽  
Emission Power ◽  
Adiabatic Flame Temperature ◽  
Combustion Technology ◽  
Zero Emission

Abstract The stable and flexible micromixer (MM) gas-turbine technology is coupled with hydrogen (H2) enrichment to present an oxy-methane combustor that can sustain highly diluted flames for application in the Allam cycle for zero-emission power production. MMs have never been tested under oxy-fuel conditions, which highlights the novelty of the present study. The operability window was quantified over ranges of fuel hydrogen fraction (HF) and oxidizer oxygen fraction OF. The MM showed superior stability, allowing for reducing OF down to 21% (by vol.) without H2 enrichment, which satisfies the dilution requirements (23%) of the primary reaction zone within the Allam-cycle combustor. By comparison, swirl-based burners from past studies exhibited a ∼30% minimum threshold. Enriching the fuel with H2 boosted flame stability and allowed for reducing OF further down to a record-low value of 13% at HF = 65% (by vol.) in fuel mixture. Under these highly diluted conditions, the adiabatic flame temperature is 990°C (1800°F), which is substantially lower than the lean blowout limit of most known technologies of lean premixed air-fuel combustion in gas-turbine applications. The results also showed that H2 enrichment has minimal effect on the adiabatic flame temperature and combustor power density (MW/m3/atm), which facilitates great operational flexibility in adjusting HF to sustain flame stability without influencing the Allam cycle peak temperature or affecting the turbine health. MM combustion with H2 enrichment is thus a recommended technology for controlled-emission, fuel/oxidizer-flexible combustion in gas turbines.

Experimental Study of a Flameless Gas Turbine Combustor

2006 ◽  
Author(s):  
Guoqiang Li ◽  
Ephraim J. Gutmark ◽  
Nick Overman ◽  
Michael Cornwell ◽  
Dragan Stankovic ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Flame Temperature ◽  
Nox Emissions ◽  
Preheat Temperature ◽  
Gas Turbine Combustor ◽  
Flameless Combustion ◽  
Combustion Dynamics ◽  
Flow Rates ◽  
Air Mass ◽  
Chamber Diameter

This paper presents experimental data, performed at atmospheric conditions, on a novel flameless combustor with application to gas turbine engines. Flameless combustion is characterized by distributed flame and even temperature distribution achieved at conditions of high preheat air temperature and sufficiently large amounts of recirculating low oxygen concentration exhaust gases. Extremely low emissions of NOx, CO, and UHC are reported in this paper for flameless combustion in a multiple jets premixed gas turbine combustor. Measurements of the flame chemiluminescence, CO and NOx emissions, acoustic pressure, temperature field, and velocity field reveal the influence of various parameters including: preheat temperature, inlet air mass flow rate, combustor exhaust nozzle contraction ratio, and combustor chamber diameter on emissions and combustion dynamics. The data indicate that greater air mass flow rates, thus larger pressure drop, promotes the formation of flameless combustion and lower NOx emissions for the same flame temperature. This flameless combustor is basically a premixed combustion in which NOx emissions is an exponential function of the flame temperature regardless of different air preheating temperatures. High preheat temperature and flow rates also help in forming stable combustion which is another advantageous feature of flameless combustion. The effects of the combustor exhaust contraction and the combustion chamber diameter on emissions and combustion dynamics are discussed.

scholarly journals Influence of Gas Turbine Combustor Design and Operating Parameters on Effectiveness of NOx Suppression by Injected Steam or Water

1984 ◽  
Author(s):  
G. L. Touchton
Keyword(s):  
Gas Turbine ◽  
Energy Content ◽  
Water Injection ◽  
Flame Temperature ◽  
Steam Injection ◽  
Combined Cycle ◽  
Gas Turbine Combustor ◽  
Turbulent Diffusion Flame ◽  
Air Stream ◽  
Design Changes

Steam or water injection has become the state-of-the-art abatement technique for NOx, with steam strongly preferred for combined-cycle application. In combined-cycle plants, the degradation of the plant efficiency due to steam injection into the gas turbine combustor provides a powerful incentive for minimizing this flow over the entire plant operating map. This paper presents the results of extensive tests carried out on a variety of gas turbine combustor designs. Both test stand and field test data are presented. The usual fuel in the tests is methane; however, some data are presented for combustion of No. 2 distillate oil and intermediate Btu gas fuel. Similarly, the usual inert injected is steam, but some water injection data are included for comparison. The results support the conclusions: 1. Steam and water injection suppress NOx exclusively through thermal mechanisms, i.e., by lowering the peak flame temperature. 2. Design changes have little effect on NOx suppression effectiveness of steam or water in jet-stirred or swirl-mixed combustors. 3. Primary zone injection of steam in methane-fueled, jet-stirred combustors is equally effective whether the steam enters with an air stream or with the fuel stream. 4. Water-to-fuel ratio corrected to equivalent energy content correlates NOx suppression effectiveness for turbulent diffusion flame combustors.

Numerical Simulations of Low-Btu Coal Gas Combustion in a Gas Turbine Combustor

1991 ◽  
Author(s):  
Ajay K. Agrawal ◽  
Tah-Teh Yang
Keyword(s):  
Gas Turbine ◽  
Mixture Fraction ◽  
Flame Temperature ◽  
Three Dimensional ◽  
Reacting Flow ◽  
Gas Temperature ◽  
Gas Turbine Combustor ◽  
Gas Combustion ◽  
Complete Combustion ◽  
Coal Gas

A numerical model for turbulent reacting flow is described and applied for predictions in an industrial gas turbine combustor operating on low-Btu coal gas. The model, based on fast-reaction limit, used Favre averaged conservation equations with the standard k-ε model of turbulence. Effects of turbulent fluctuations on chemistry are described statistically in terms of the mean, variance and probability density function (assumed to be β-distribution) of the mixture fraction. Two types of geometric approximations, namely axisymmetric and three-dimensional, were used to model the combustor. Computations were performed with (a) no swirl (b) weak swirl and (c) strong swirl at the fuel and primary air inlets. Essentially, the same bulk mean temperature distributions were obtained for axisymmetric and three-dimensional calculations while the computed pattern factors and the liner wall temperatures for the two differed significantly. Complete combustion was predicted with strong swirl, a result supported by the available test data. The maximum liner wall temperature predicted for three-dimensional calculations compared favorably with the experimental data while the predicted maximum exhaust gas temperature differed by ≈120 K. The difference was attributed to measurement uncertainties, model assumptions and lack of accurate data at the inlets. The maximum flame temperature was below 1,850 K indicating that thermal NOx may be insignificant.

Combustion Dynamics Diagnostics and Mitigation on a Prototype Gas Turbine Combustor

2012 ◽  
Author(s):  
Bassam S. Mohammad ◽  
Preetham Balasubramanyam ◽  
Keith McManus ◽  
Jeffrey Ruszczyk ◽  
Ahmed M. Elkady ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Flame Temperature ◽  
Operating Conditions ◽  
Published Data ◽  
Stable Operation ◽  
Nox Emissions ◽  
Gas Turbine Combustor ◽  
Combustion Dynamics ◽  
The Impact ◽  
Intermittent Mode

Combustion dynamics have detrimental effects on hardware durability as well as combustor performance and emissions. This paper presents a detailed study on the impact of combustion dynamics on NOx and CO emissions generated from a prototype gas turbine combustor operating at a pressure of 180 psia (12.2 bars) with a pre-heat temperature of 720 F (655.3 K) (E-class machine operating conditions). Two unstable modes are discussed. The first is an intermittent mode, at 750 Hz, that emerges at flame temperatures near 2900°F (1866.5 K), resulting in high NOx and CO emissions. With increasing fuel flow, NOx and CO emissions continue to increase until the flame temperature reaches approximately 3250°F (2061 K), at which point the second acoustic mode begins to dominate. Flame images indicate that the intermittent mode is associated with flame motion which induces the high NOx and CO emissions. The second mode is also a 750 Hz, but of constant amplitude (no intermittency). Operation in this second 750 Hz mode results in significantly reduced NOx and CO emissions. At pressures higher than 180 psia (12.2 bars), the intermittent mode intensifies, leading to flashback at flame temperatures above 2850°F (1839 K). In order to mitigate the intermittent mode, a second configuration of the combustor included an exit area restriction. The exit area restriction eliminated the intermittent mode, resulting in stable operation and low emissions over a temperature range of 2700–3200°F (1755–2033 K). A comparison of the NOx emissions, as function of flame temperature, with previous published data for perfectly premixed indicates that, while the low amplitude 750 Hz oscillations have little effect, the intermittent mode significantly increases emissions. Mode shape analysis shows that the 750 Hz instability corresponds to the 1/4 wave axial mode. In the current research a ceramic liner is used while the previous published data was collected with a quartz liner. Typically, quartz is avoided due to reductions in effective flame temperature by radiation losses. Experiments showed that NOx emissions were not affected by the combustor liner type. This agreement between the quartz and ceramic liners data indicates limited effect from the radiation heat losses on NOx emissions.

Influence of Gas Turbine Combustor Design and Operating Parameters on Effectiveness of NOx Suppression by Injected Steam or Water

1985 ◽  
Vol 107 (3) ◽  
pp. 706-713 ◽  
Author(s):  
G. L. Touchton
Keyword(s):  
Gas Turbine ◽  
Energy Content ◽  
Water Injection ◽  
Flame Temperature ◽  
Steam Injection ◽  
Combined Cycle ◽  
Gas Turbine Combustor ◽  
Turbulent Diffusion Flame ◽  
Air Stream ◽  
Design Changes

Steam or water injection has become the state-of-the-art abatement technique for NOx, with steam strongly preferred for combined-cycle application. In combined-cycle plants, the degradation of the plant efficiency due to steam injection into the gas turbine combustor provides a powerful incentive for minimizing this flow over the entire plant operating map. This paper presents the results of extensive tests carried out on a variety of gas turbine combustor designs. Both test stand and field test data are presented. The usual fuel in the tests is methane; however, some data are presented for combustion of No. 2 distillate oil and intermediate Btu gas fuel. Similarly, the usual inert injected is steam, but some water injection data are included for comparison. The results support the conclusions: 1. Steam and water injection suppress NOx exclusively through thermal mechanisms, i.e., by lowering the peak flame temperature. 2. Design changes have little effect on NOx suppression effectiveness of steam or water in jet-stirred or swirl-mixed combustors. 3. Primary zone injection of steam in methane-fueled, jet-stirred combustors is equally effective whether the steam enters with an air stream or with the fuel stream. 4. Water-to-fuel ratio corrected to equivalent energy content correlates NOx suppression effectiveness for turbulent diffusion flame combustors.

Preliminary Analysis of a New Methodology for Flameless Combustion in Gas Turbine Combustors

2007 ◽  
Author(s):  
Yeshayahou Levy ◽  
G. Arvind Rao ◽  
Valery Sherbaum
Keyword(s):  
Gas Turbine ◽  
Oxygen Concentration ◽  
Combustion Zone ◽  
Flame Temperature ◽  
Carbon Dioxide Concentration ◽  
Operating Conditions ◽  
Gas Turbine Combustor ◽  
Flameless Combustion ◽  
Gas Turbine Combustors ◽  
Wide Range

Flameless combustion is one of the most promising technologies that can meet the stringent demands of reduced pollution and increased reliability in future gas turbine engines. Although this new combustion technology has been successfully applied to industrial furnaces, there are inherent problems that prevent application of this promising technology in a gas turbine combustor. One of the main problems is the need for recirculating large amount of burnt gases with low oxygen content, within limited volume, and over a wide range of operating conditions. In the present paper, thermodynamic analysis of a novel combustion methodology operating in the flameless combustion regime for a gas turbine combustor is carried out from the first principles, with an objective to reduce oxygen concentration and temperature in the primary combustion zone. The present analysis shows that unlike in the conventional gas turbine combustor, transferring heat from primary combustion zone to secondary (annulus) cooling air can substantially reduce oxygen concentration in reactants and the combustion temperature, thus reducing NOx formation by a large margin. In addition, to reduce the peak temperature, the proposed methodology is conceptualised / designed such that energy from fuel is released in two steps, hence reducing the peak flame temperature substantially. The new proposed methodology with internal conjugate heat transfer is compared vis-a`-vis to other existing schemes and the benefits are brought out explicitly. It is found that transferring heat from the combustion zone reduces oxygen concentration and increases carbon-dioxide concentration in the combustor, thus creating an environment conducive for flameless combustion. In addition, a schematic of a practical engineering design working on the new proposed methodology is presented. This new methodology, which calls for transfer of heat from the primary combustion zone to alternative air streams, is expected to change the way gas turbine combustors will be designed in the future.

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