Genetti, D
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.
Predicting C-13 NMR Measurements of the Chemical Structure of Coal Based on Elemental Composition and Volatile Matter Content
Genetti, D., Fletcher, T.H. and Pugmire, R.J.
Energy & Fuels, 13:60-68 (1999).
A model that predicts the amount and distribution between tar and light gas of nitrogen released during devolatilization has been developed and incorporated into the Chemical Percolation Devolatilization (CPD) model. This work represents the first volatile nitrogen release model developed based on C-13 NMR measurements of coal structure. This work also represents the first volatile nitrogen release model evaluated by comparing model predictions with chemical structural features of the char (determined by C-13 NMR spectral analyses). The model is limited to nitrogen release during primary pyrolysis, and assumes that all light gas nitrogen is HCN. Model predictions of nitrogen release compare well with measured values for most coals and devolatilization conditions tested.
An Advanced Model of Coal Devolatilization Based on Chemical Structure
Genetti, D.
An Advanced Model of Coal Devolatilization Based on Chemical Structure, M.S./BYU, Mechanical Engineering Department, April 1999. Advisor: Fletcher
1998
Development and Application of a Correlation of C-13 NMR Chemical Structural Analyses of Coal Based on Elemental Composition and Volatile Matter Content
Genetti, D. and Fletcher, T.H.
Accepted for publication, Energy and Fuels, 1998.
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 spectral analysis of coal. Solid-state 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 nonlinear correlation has been developed that predicts the chemical structure parameters of both U.S. and non-U.S. coals generally measured by C-13 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 (sigma + 1). The correlation is based on ultimate and proximate analyses, which are 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.
1997
Predicting C-13 NMR Measurements of Chemical Structure of Coal Based on Elemental Composition and Volatile Matter Content
Genetti, D. and Fletcher, T.H.
ACS Division of Fuel Chemistry Pre Prints, 42(1) 194-98, April 1997. Funded by US Department of Energy/University Coal Research and ACERC.
Devolatilization models based on quantitative measurements of chemical structure, such as available through C-13 NMR analysis, have been successful in predicting tar volatiles yields as a function of heating rate, temperature, pressure, and coal type. An example of such a devolatilization model is the CPD model, developed in ACERC. However, due to limited resources, C-13 NMR structural parameters have only been obtained for about 35 coals at the present time. Industrial interest in coal devolatilization has led to several attempts to correlate structural parameters affecting devolatilization as a function of the ultimate analysis of coals. A triangular (i.e., linear) interpolation technique is used to estimate the input parameters for one current devolatilization model, while another popular model uses a procedure that estimates the coal structural parameters based on simple linear correlations of ultimate analysis.
An extensive statistical analysis to determine the validity of linear correlations of C-13 NMR structural parameters based on ultimate analysis was performed. A database including elemental composition, the ASTM volatile matter content, and C-13 NMR structural parameters for 30 coals of widely varying rank and composition was used in the analysis. The database was closely examined using the SPSS® statistical computer package. Using SPSS®, a correlation matrix was calculated between all of the chemical structural parameters obtained from the NMR analysis. From the correlation matrix, the strength of relationships between the individual elements and the derived parameters were easily determined. The parameters were also examined for relationships among themselves. Multi-variate linear regression was then performed to derive equations that predict each of the parameters as a function of the elemental composition and volatile matter content. The r² value was the determined for each correlation. The r² value is the coefficient of determination which determines the relative strength of correlation (r²=1 is a perfect correlation). In this analysis the r² values ranged from 0.17 for sigma+1 to 0.59 for Md (r²=0.49 Po and r²=0.38 for MWcl). The low r² values indicate only a weak linear correlation between the C-13 NMR structural parameters and the ultimate analysis. However, even when r² is zero, a strong non-linear correlation is possible. As a result of this study, it was determined that correlations base on linear regressions of ultimate analysis are unsuitable for predicting C-13 NMR structural parameters with reasonable accuracy.
A non-linear correlation has now been developed that predicts the chemical structure parameters generally measured by C-13 NMR and required for the CPD devolatilization model: (1) the average molecular weight per side chain (Mdelta); (2) the average molecular weight per aromatic cluster (MWcl); (3) the ratio of bridges to total attachments (Po); and (4) the total attachments per cluster (sigma+1). The correlation is based on ultimate and proximate analyses, which are generally known for most coals.
The correlation has been used to estimate the chemical structure parameters generally obtained from C-13 NMR measurements, and then coal devolatilization predictions were performed using the CPD model and compared with measured total volatiles yields. The combination of the empirical model and the CPD model accurately predicts tar and total volatiles yields for coals with carbon content (daf) ranging from 65 percent to 94 percent.
Genetti, D
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.
Predicting C-13 NMR Measurements of the Chemical Structure of Coal Based on Elemental Composition and Volatile Matter Content
Genetti, D., Fletcher, T.H. and Pugmire, R.J.
Energy & Fuels, 13:60-68 (1999).
A model that predicts the amount and distribution between tar and light gas of nitrogen released during devolatilization has been developed and incorporated into the Chemical Percolation Devolatilization (CPD) model. This work represents the first volatile nitrogen release model developed based on C-13 NMR measurements of coal structure. This work also represents the first volatile nitrogen release model evaluated by comparing model predictions with chemical structural features of the char (determined by C-13 NMR spectral analyses). The model is limited to nitrogen release during primary pyrolysis, and assumes that all light gas nitrogen is HCN. Model predictions of nitrogen release compare well with measured values for most coals and devolatilization conditions tested.
An Advanced Model of Coal Devolatilization Based on Chemical Structure
Genetti, D.
An Advanced Model of Coal Devolatilization Based on Chemical Structure, M.S./BYU, Mechanical Engineering Department, April 1999. Advisor: Fletcher
1998
Development and Application of a Correlation of C-13 NMR Chemical Structural Analyses of Coal Based on Elemental Composition and Volatile Matter Content
Genetti, D. and Fletcher, T.H.
Accepted for publication, Energy and Fuels, 1998.
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 spectral analysis of coal. Solid-state 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 nonlinear correlation has been developed that predicts the chemical structure parameters of both U.S. and non-U.S. coals generally measured by C-13 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 (sigma + 1). The correlation is based on ultimate and proximate analyses, which are 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.
1997
Predicting C-13 NMR Measurements of Chemical Structure of Coal Based on Elemental Composition and Volatile Matter Content
Genetti, D. and Fletcher, T.H.
ACS Division of Fuel Chemistry Pre Prints, 42(1) 194-98, April 1997. Funded by US Department of Energy/University Coal Research and ACERC.
Devolatilization models based on quantitative measurements of chemical structure, such as available through C-13 NMR analysis, have been successful in predicting tar volatiles yields as a function of heating rate, temperature, pressure, and coal type. An example of such a devolatilization model is the CPD model, developed in ACERC. However, due to limited resources, C-13 NMR structural parameters have only been obtained for about 35 coals at the present time. Industrial interest in coal devolatilization has led to several attempts to correlate structural parameters affecting devolatilization as a function of the ultimate analysis of coals. A triangular (i.e., linear) interpolation technique is used to estimate the input parameters for one current devolatilization model, while another popular model uses a procedure that estimates the coal structural parameters based on simple linear correlations of ultimate analysis.
An extensive statistical analysis to determine the validity of linear correlations of C-13 NMR structural parameters based on ultimate analysis was performed. A database including elemental composition, the ASTM volatile matter content, and C-13 NMR structural parameters for 30 coals of widely varying rank and composition was used in the analysis. The database was closely examined using the SPSS® statistical computer package. Using SPSS®, a correlation matrix was calculated between all of the chemical structural parameters obtained from the NMR analysis. From the correlation matrix, the strength of relationships between the individual elements and the derived parameters were easily determined. The parameters were also examined for relationships among themselves. Multi-variate linear regression was then performed to derive equations that predict each of the parameters as a function of the elemental composition and volatile matter content. The r² value was the determined for each correlation. The r² value is the coefficient of determination which determines the relative strength of correlation (r²=1 is a perfect correlation). In this analysis the r² values ranged from 0.17 for sigma+1 to 0.59 for Md (r²=0.49 Po and r²=0.38 for MWcl). The low r² values indicate only a weak linear correlation between the C-13 NMR structural parameters and the ultimate analysis. However, even when r² is zero, a strong non-linear correlation is possible. As a result of this study, it was determined that correlations base on linear regressions of ultimate analysis are unsuitable for predicting C-13 NMR structural parameters with reasonable accuracy.
A non-linear correlation has now been developed that predicts the chemical structure parameters generally measured by C-13 NMR and required for the CPD devolatilization model: (1) the average molecular weight per side chain (Mdelta); (2) the average molecular weight per aromatic cluster (MWcl); (3) the ratio of bridges to total attachments (Po); and (4) the total attachments per cluster (sigma+1). The correlation is based on ultimate and proximate analyses, which are generally known for most coals.
The correlation has been used to estimate the chemical structure parameters generally obtained from C-13 NMR measurements, and then coal devolatilization predictions were performed using the CPD model and compared with measured total volatiles yields. The combination of the empirical model and the CPD model accurately predicts tar and total volatiles yields for coals with carbon content (daf) ranging from 65 percent to 94 percent.