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Flammability limits of Low Btu gases : Computations in a perfectly stirred reactor and experiments

Hermann, Fredrik LU ; Ruck, Thomas; Klingmann, Jens LU and Mauss, Fabian LU (2001) ASME Turbo Expo 2001: Power for Land, Sea, and Air, GT 2001 2.
Abstract

The demand for gas turbines suitable for Low Btu gases is increasing worldwide. This paper presents a theoretical and experimental investigation of the flammability limits of Low Btu gases for gas turbine applications. Most modern gas turbines utilize premixed combustion, making it important to know at which fuel-air ratio the flame extinguishes. The flammability limit for a gaseous fuel is a property, which is coupled to both thermodynamic quantities and the shape of the combustion chamber. Consequently, this property is characteristic for each combustor and for each fuel. The experiments were made in an atmospheric pressure premixed combustor at Alstom Power Technology Ltd. Switzerland, adapted for Low Btu gaseous fuels. Five... (More)

The demand for gas turbines suitable for Low Btu gases is increasing worldwide. This paper presents a theoretical and experimental investigation of the flammability limits of Low Btu gases for gas turbine applications. Most modern gas turbines utilize premixed combustion, making it important to know at which fuel-air ratio the flame extinguishes. The flammability limit for a gaseous fuel is a property, which is coupled to both thermodynamic quantities and the shape of the combustion chamber. Consequently, this property is characteristic for each combustor and for each fuel. The experiments were made in an atmospheric pressure premixed combustor at Alstom Power Technology Ltd. Switzerland, adapted for Low Btu gaseous fuels. Five different residual gases from chemical factories were investigated. The gases consisted of methane, carbon monoxide, hydrogen and nitrogen, with lower heating values about 2-3.5 MJ/kg for all examined gases (Table 1). A steady state Perfectly Stirred Reactor (PSR) was used as a model for the primary combustion zone. The reactions were modeled by a detailed mechanism for methane with 61 species and 667 reactions, developed by Warnatz [1]. The PSR calculations were done by decreasing the residence time until the combustion in the PSR extinguished. These calculations were repeated for different equivalence ratios to obtain the relation between the residence time and the limit of flammability. The calculations showed a relationship between the residence time in the PSR and the extinction point. It was found that the computed values of the flammability limits, or more correctly called stability limits, qualitatively follow the experimental results. However, since the computational results are strongly dependent on the residence time, a comparison with the experiments must include the residence time of the real burner, which is difficult to define.

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Please use this url to cite or link to this publication:
author
organization
publishing date
type
Chapter in Book/Report/Conference proceeding
publication status
published
subject
host publication
Coal, Biomass and Alternative Fuels; Combustion and Fuels; Oil and Gas Applications; Cycle Innovations
volume
2
pages
8 pages
publisher
American Society of Mechanical Engineers(ASME)
conference name
ASME Turbo Expo 2001: Power for Land, Sea, and Air, GT 2001
conference location
New Orleans, LA, United States
conference dates
2001-06-04 - 2001-06-07
external identifiers
  • scopus:10244277442
ISBN
9780791878514
DOI
10.1115/2001-GT-0004
language
English
LU publication?
yes
id
203c7bf5-dafb-411d-8c33-04cf26c7076e
date added to LUP
2018-10-18 12:43:29
date last changed
2019-02-20 11:31:57
@inproceedings{203c7bf5-dafb-411d-8c33-04cf26c7076e,
  abstract     = {<p>The demand for gas turbines suitable for Low Btu gases is increasing worldwide. This paper presents a theoretical and experimental investigation of the flammability limits of Low Btu gases for gas turbine applications. Most modern gas turbines utilize premixed combustion, making it important to know at which fuel-air ratio the flame extinguishes. The flammability limit for a gaseous fuel is a property, which is coupled to both thermodynamic quantities and the shape of the combustion chamber. Consequently, this property is characteristic for each combustor and for each fuel. The experiments were made in an atmospheric pressure premixed combustor at Alstom Power Technology Ltd. Switzerland, adapted for Low Btu gaseous fuels. Five different residual gases from chemical factories were investigated. The gases consisted of methane, carbon monoxide, hydrogen and nitrogen, with lower heating values about 2-3.5 MJ/kg for all examined gases (Table 1). A steady state Perfectly Stirred Reactor (PSR) was used as a model for the primary combustion zone. The reactions were modeled by a detailed mechanism for methane with 61 species and 667 reactions, developed by Warnatz [1]. The PSR calculations were done by decreasing the residence time until the combustion in the PSR extinguished. These calculations were repeated for different equivalence ratios to obtain the relation between the residence time and the limit of flammability. The calculations showed a relationship between the residence time in the PSR and the extinction point. It was found that the computed values of the flammability limits, or more correctly called stability limits, qualitatively follow the experimental results. However, since the computational results are strongly dependent on the residence time, a comparison with the experiments must include the residence time of the real burner, which is difficult to define.</p>},
  author       = {Hermann, Fredrik and Ruck, Thomas and Klingmann, Jens and Mauss, Fabian},
  isbn         = {9780791878514},
  language     = {eng},
  location     = {New Orleans, LA, United States},
  month        = {01},
  pages        = {8},
  publisher    = {American Society of Mechanical Engineers(ASME)},
  title        = {Flammability limits of Low Btu gases : Computations in a perfectly stirred reactor and experiments},
  url          = {http://dx.doi.org/10.1115/2001-GT-0004},
  volume       = {2},
  year         = {2001},
}