Experimental Investigations on NOx Emission and Combustion Dynamics in an Axial Fuel Staging Combustor

Abstract Enabled by national commercialization of massive shale resources, Gas Turbines continue to be the backbone of power generation in the US. With the ever-increasing demand on efficiency, GT combustion sections have evolved to include shorter combustion lengths and multiple axial staging of the fuel, while at the same time operating at ever increasing temperatures. This paper presents the results of very detailed Large Eddy Simulations of one (or two) combustor can(s) for a 7HA GE Gas Turbine Engine over a range of operating parameters. The model of the simulated combustor can(s) includes (include) all the details of the combustor from compressor diffuser to the end of the stationary part of the first stage of the turbine. It includes the geometries of multiple pre-mixers within the combustion can(s) and the complete design features for axial fuel staging. All simulations in this work are performed using the CharLES flow solver developed by Cascade Technologies. CharLES is a suite of massively parallel CFD tools designed specifically for multiphysics LES in high-fidelity engineering applications. Thermo acoustic results from LES were validated first in the physical GE lab and then in full-engine testing. Both the trend as well as the predicted amplitudes for the excited axial dominant combustion mode matched the data produced in the lab and in the engine. The simulations also revealed insight into the ingestion of hot gases by different hardware pieces that may occur when machine operates under medium to high combustion dynamics amplitudes. This insight then informed the subsequent design changes which were made to the existing hardware to mitigate the problems encountered.

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Reduction of NOx emission in turbulent combustion by fuel-staging/effects of mixing and stoichiometry in the reduction zone

Symposium (International) on Combustion ◽

10.1016/s0082-0784(89)80130-4 ◽

1989 ◽

Vol 22 (1) ◽

pp. 1193-1203 ◽

Cited By ~ 26

Author(s):

T. Kolb ◽

'P. Jansohn ◽

W. Leuckel

Keyword(s):

Turbulent Combustion ◽

Nox Emission ◽

Reduction Zone ◽

Fuel Staging ◽

Reduction Of Nox

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Numerical and experimental investigations of the NOx emission characteristics of CH4-air coflow jet flames

Fuel ◽

10.1016/j.fuel.2004.07.001 ◽

2004 ◽

Vol 83 (17-18) ◽

pp. 2323-2334 ◽

Cited By ~ 19

Author(s):

C.E. Lee ◽

C.B. Oh ◽

J.H. Kim

Keyword(s):

Nox Emission ◽

Experimental Investigations ◽

Emission Characteristics ◽

Jet Flames

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An Experimental Study on Combustion Dynamics and NOx Emission of a Swirl Stabilized Combustor with Secondary Fuel Injection

Journal of Thermal Science and Technology ◽

10.1299/jtst.5.266 ◽

2010 ◽

Vol 5 (2) ◽

pp. 266-281 ◽

Cited By ~ 3

Author(s):

Rouzbeh RIAZI ◽

Mohammad FARSHCHI ◽

Masayasu SHIMURA ◽

Mamoru TANAHASHI ◽

Toshio MIYAUCHI

Keyword(s):

Experimental Study ◽

Fuel Injection ◽

Nox Emission ◽

Combustion Dynamics ◽

Secondary Fuel

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Experimental investigations of ion current in liquid-fuelled gas turbine combustors

International Journal of Spray and Combustion Dynamics ◽

10.1177/1756827716688477 ◽

2017 ◽

Vol 9 (3) ◽

pp. 172-185 ◽

Cited By ~ 1

Author(s):

J Christopher Wollgarten ◽

Nikolaos Zarzalis ◽

Fabio Turrini ◽

Antonio Peschiulli

Keyword(s):

Feedback Control ◽

Vortex Core ◽

Ion Current ◽

Injection System ◽

Experimental Investigations ◽

Control Loop ◽

Combustion Dynamics ◽

Lean Blowout ◽

Precessing Vortex Core ◽

Interaction Mode

This work covers investigations of the static and dynamic behaviour of a confined, co-swirled and liquid-fuelled airblast injection system. The focus lies on the application of ion current sensors for the qualitative measurement of the heat release rate or for flame monitoring purposes in complex technical combustion processes. The ion current sensor is to operate in a feedback control loop in order to react on combustion dynamics in real time. The first part of the work analyses experimental data, which were obtained with different techniques, e.g. dynamic pressure, chemiluminescence, fine-wire thermocouples and ion current. The results show that the thermo-acoustic instability and the precessing vortex core generate an interaction mode. The frequency of this interaction mode is the difference of the other two modes. This has not yet been observed for partially premixed and liquid-fuelled injection systems before and also was not detected by the chemiluminescence of the flame. The ion current measurement technique is able to detect the helical mode of the precessing vortex core as well as the interaction frequency, leading to the conclusion that the chemical reactions are influenced by this helical structure. Contour maps of the frequencies reveal this influence in the outer shear layer. The second part of the study focused on the ion current probe as a method to predict static combustion instabilities, such as lean blowout. According to the results, the ion current is a fast responding method to detect lean blowout, provided that the detector is mounted at a suitable position. Measurements at different positions in the flame were compared with phase-locked chemiluminescence measurements. Precursors in the ion current signal for lean-blowout prediction were found using a statistical approach, which is based on ion peak distance. The precursor events allow for the use of this approach with a feedback control loop in future applications.

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Development of Ceramic Gas Turbine Combustor for 300kW-Class(CGT301)

Volume 2: Coal, Biomass and Alternative Fuels; Combustion and Fuels; Oil and Gas Applications; Cycle Innovations ◽

10.1115/97-gt-440 ◽

1997 ◽

Author(s):

Tsukasa Saitou ◽

Jun’ichi Sato

Keyword(s):

Gas Turbine ◽

Load Condition ◽

Staging System ◽

Nox Emission ◽

Full Load ◽

Stable Combustion ◽

Lean Premixed ◽

Fuel Staging ◽

Primary Type ◽

Low Nox Emission

The combustor for 300kW class ceramic gas turbine (CGT301) has been developed to achieve high thermal efficiency of 42%. The combustor inlet air temperature and the turbine inlet temperature(TIT) are higher compared with the conventional same class gas turbine. The “pilot” CGT system, with a recuperator to recover the waste heat in the exhaust gas, can heat combustor inlet air up to 1013K(740°C) at TIT of 1623K(1350°C). Low NOx emission is one of the important problems for the CGT combustor. To solve the problem, the lean premixed combustion method was applied. Stable combustion is another important problem for the lean premixed combustor. To solve the problem, this combustor employed the variable geometory system and the fuel staging system. The former controlled the temperature in the combustion zone. The latter optimized the distribution of air/fuel concentration in the mixing zone. The CGT system has achieved both stable combustion and low NOx emission. NOx emission was reduced to 17.6 ppm against the “primary type” CGT target of 70 ppm under the full load condition at TIT of 1200°C in combustor rig test. The engine tests of “primary type” CGT with a ceramic combustor, which did not employ the variable geometry system and the fuel staging system, were conducted successfully for a total of 32 hours without any damage of the ceramic combustor under the full load condition.

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The Effect of Electric Field Configuration on the Thermo-Chemical Conversion of Straw Pellets

Latvian Journal of Physics and Technical Sciences ◽

10.2478/lpts-2020-0022 ◽

2020 ◽

Vol 57 (4) ◽

pp. 65-76

Author(s):

I. Barmina ◽

A. Kolmickovs ◽

R. Valdmanis ◽

S. Vostrikovs ◽

M. Zake

Keyword(s):

Electric Field ◽

Energy Production ◽

Chemical Conversion ◽

Field Configuration ◽

Heat Energy ◽

Ion Current ◽

Experimental Investigations ◽

Electric Field Effect ◽

Combustion Dynamics ◽

Dc Electric Field

AbstractWith the aim to control and improve the thermo-chemical conversion of straw pellets, the experimental investigations of the DC electric field effect on the combustion dynamics and heat energy production were made. The electric field effect on the gasification/combustion characteristics was studied using three different positions of the positively charged electrode in flame. First, the electrode was positioned coaxially downstream the flame flow. Next, the electrode was positioned coaxially upstream the flame flow and, finally, the electrode was positioned across the downstream flow. The bias voltage of the electrode varied in the range from 0.6 up to 1.8 kV, while the ion current in flame was limited to 5 mA. The results of experimental investigations show that the DC electric field intensifies the thermal decomposition of straw pellets and enhances mixing of volatiles with air causing changes in combustion dynamics and heat energy production, which depend on position and the bias voltage of the electrode. The increase in the average volume fraction of CO2 (by 6 %) and the decrease in the mass fraction of unburned volatiles in the products (CO by 60 % and H2 by 73 %) for the upstream field configuration of the electrode and the ion current 0.5–1.8 mA indicate more complete combustion of volatiles.

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