Flores, DV
2000
The Use of Two Mixture Fractions to Treat Coal Combustion in Turbulent Pulverized-Coal Flames
Flores, D.V. and Fletcher, T.H.
Combustion Science and Technology, 150, 1-26 (2000).
Contact: Fletcher
1999
Modeling Nitrogen Release During Devolatilization on the Basis of Chemical Structure of Coal
Genetti, D. and Fletcher, T.H.
Energy & Fuels, 13, 1082-1091 (1999).
C-13 NMR spectroscopy has been shown to be an important tool in the characterization of coal structure. Important quantitative information about the carbon skeletal structure is obtained through C-13 NMR analysis techniques have progressed beyond the mere determination of aromaticity, and can now describe features such as the number of aromatic carbons per cluster and the number of attachments per aromatic cluster. These C-13 NMR data have been used to better understand the complicated structure of coal, to compare structural differences in coal, tar, and char, and to model coal devolatilization. Unfortunately, due to the expense of the process, extensive C-13 NMR data are not available for most coals. A non-linear correlation has been developed that predicts the chemical structure parameters of both US and non-US coals generally measured by 13C NMR and often required for advanced devolatilization models. The chemical structure parameters correlated include: (i) the average molecular weight per side chain (Mdelta); (ii) the average molecular weight per aromatic cluster (Mcl); (iii) the ratio of bridges to total attachments (p0); and (iv) the total attachments per cluster (+1). The correlation is based on ultimate and proximate analysis, which is generally known for most coals. C-13 NMR data from 30 coals were used to develop this correlation. The correlation has been used to estimate the chemical structure parameters generally obtained from C-13 NMR measurements, and then applied to coal devolatilization predictions using the CPD model and compared with measured total volatiles and tar yields. The predicted yields compare well with measured yields for most coals.
1996
The Use of Two Mixture Fractions to Treat Coal Combustion Products in Turbulent Pulverized-Coal Flames
Flores, D.V.
The Use of Two Mixture Fractions to Treat Coal Combustion Products in Turbulent Pulverized-Coal Flames, M.S./BYU, April 1996. Advisor: Fletcher
Simultaneous Measurements of the Temperature and Species Concentration of Premixed Natural Gas Flames Using a Dual Dye, Single Strokes CARS System
Flores, D.V. and Hedman, P.O.
Proceedings at the Fall Meeting of the Western States Section/Combustion Institute, The University of Southern California, Los Angeles, California, October 28-29, 1996. Funded by ACERC and Morgantown Energy Technology Center (ATS).
The objective of this study was to obtain temperature and species (CO, CO2, O2, N2 and H2O) concentration measurements using coherent anti-Stokes Raman spectroscopy (CARS) from and atmospheric pressure, swirling, turbulent, premixed natural gas/air flame in a model combustor that simulates the characteristics of a utility gas turbine engine. The Brigham Young University (BYU)/ACERC laboratory-scale, gas-turbine combustor (LSGTC) simulates many of the key combustion characteristics of commercial gas turbines, while providing optical access for the CARS laser beams. In situ data (temperature and species concentrations) have been collected as a function of radial and axial position at several locations over the combustion zone.
This paper demonstrates the applicability of two new developments made at the BYU/ACERC optics laboratory: (1) a new CARS systems that uses a dual dye, single Stokes laser with sufficient spectral band-width to simultaneously excite the Strokes frequencies of N2, CO, O2, CO2 and (2) a newly proposed method that allows the calculation of additional species concentrations from reduced CARS data from local elemental mass balances. The species concentrations calculated include H2O, and unaccounted-for hydrogen (H*) and carbon (C*).
Iso-coutour maps of temperature and species concentrations from instantaneous CARS measurements on premixed natural gas flames are presented. The combustor was operated at a medium swirl number of 0.74 and a fuel equivalence ratio of 0.65. Early results indicate that the measurements of species concentrations are self-consistent. Nevertheless CO measurements are above expected levels based on both kinetic and equilibrium predictions. Investigation on the source of this discrepancy is underway. In addition, estimated concentrations of H2O and unaccounted-for carbon (C*) and hydrogen (H*), deduced from oxygen, carbon, and hydrogen mass balances (from known premixed composition) are presented. Observations on flame behavior from these measurements are made. These data provide considerable insight into the flame behavior as well as a database for model evaluation.
Flores, DV
2000
The Use of Two Mixture Fractions to Treat Coal Combustion in Turbulent Pulverized-Coal Flames
Flores, D.V. and Fletcher, T.H.
Combustion Science and Technology, 150, 1-26 (2000).
Contact: Fletcher
1999
Modeling Nitrogen Release During Devolatilization on the Basis of Chemical Structure of Coal
Genetti, D. and Fletcher, T.H.
Energy & Fuels, 13, 1082-1091 (1999).
C-13 NMR spectroscopy has been shown to be an important tool in the characterization of coal structure. Important quantitative information about the carbon skeletal structure is obtained through C-13 NMR analysis techniques have progressed beyond the mere determination of aromaticity, and can now describe features such as the number of aromatic carbons per cluster and the number of attachments per aromatic cluster. These C-13 NMR data have been used to better understand the complicated structure of coal, to compare structural differences in coal, tar, and char, and to model coal devolatilization. Unfortunately, due to the expense of the process, extensive C-13 NMR data are not available for most coals. A non-linear correlation has been developed that predicts the chemical structure parameters of both US and non-US coals generally measured by 13C NMR and often required for advanced devolatilization models. The chemical structure parameters correlated include: (i) the average molecular weight per side chain (Mdelta); (ii) the average molecular weight per aromatic cluster (Mcl); (iii) the ratio of bridges to total attachments (p0); and (iv) the total attachments per cluster (+1). The correlation is based on ultimate and proximate analysis, which is generally known for most coals. C-13 NMR data from 30 coals were used to develop this correlation. The correlation has been used to estimate the chemical structure parameters generally obtained from C-13 NMR measurements, and then applied to coal devolatilization predictions using the CPD model and compared with measured total volatiles and tar yields. The predicted yields compare well with measured yields for most coals.
1996
The Use of Two Mixture Fractions to Treat Coal Combustion Products in Turbulent Pulverized-Coal Flames
Flores, D.V.
The Use of Two Mixture Fractions to Treat Coal Combustion Products in Turbulent Pulverized-Coal Flames, M.S./BYU, April 1996. Advisor: Fletcher
Simultaneous Measurements of the Temperature and Species Concentration of Premixed Natural Gas Flames Using a Dual Dye, Single Strokes CARS System
Flores, D.V. and Hedman, P.O.
Proceedings at the Fall Meeting of the Western States Section/Combustion Institute, The University of Southern California, Los Angeles, California, October 28-29, 1996. Funded by ACERC and Morgantown Energy Technology Center (ATS).
The objective of this study was to obtain temperature and species (CO, CO2, O2, N2 and H2O) concentration measurements using coherent anti-Stokes Raman spectroscopy (CARS) from and atmospheric pressure, swirling, turbulent, premixed natural gas/air flame in a model combustor that simulates the characteristics of a utility gas turbine engine. The Brigham Young University (BYU)/ACERC laboratory-scale, gas-turbine combustor (LSGTC) simulates many of the key combustion characteristics of commercial gas turbines, while providing optical access for the CARS laser beams. In situ data (temperature and species concentrations) have been collected as a function of radial and axial position at several locations over the combustion zone.
This paper demonstrates the applicability of two new developments made at the BYU/ACERC optics laboratory: (1) a new CARS systems that uses a dual dye, single Stokes laser with sufficient spectral band-width to simultaneously excite the Strokes frequencies of N2, CO, O2, CO2 and (2) a newly proposed method that allows the calculation of additional species concentrations from reduced CARS data from local elemental mass balances. The species concentrations calculated include H2O, and unaccounted-for hydrogen (H*) and carbon (C*).
Iso-coutour maps of temperature and species concentrations from instantaneous CARS measurements on premixed natural gas flames are presented. The combustor was operated at a medium swirl number of 0.74 and a fuel equivalence ratio of 0.65. Early results indicate that the measurements of species concentrations are self-consistent. Nevertheless CO measurements are above expected levels based on both kinetic and equilibrium predictions. Investigation on the source of this discrepancy is underway. In addition, estimated concentrations of H2O and unaccounted-for carbon (C*) and hydrogen (H*), deduced from oxygen, carbon, and hydrogen mass balances (from known premixed composition) are presented. Observations on flame behavior from these measurements are made. These data provide considerable insight into the flame behavior as well as a database for model evaluation.