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Title: CO2 Isotherms Measured on Moisture-Equilbrated Argonne Premium Coals at 550C and 15 Mpa

Abstract

Sorption isotherms, which describe the coal’s gas storage capacity, are important for estimating the carbon sequestration potential of coal seams. The DOE-NETL initiated a second inter-laboratory isotherm comparison of coals where CO2 sorption isotherms were collected on moisture-equilibrated coals at temperatures and pressures relevant to CO2 sequestration. Each laboratory used the same coal samples and followed the same general procedure; however, each laboratory used their own apparatus and isotherm measurement technique. This study investigated the inter-laboratory reproducibility of carbon dioxide isotherm measurements on moisture-equilibrated Argonne premium coal samples (Pocahontas #3, Illinois #6, and Beulah Zap). Six independent laboratories provided isotherm data on the three moisture-equilibrated coal samples at 55oC and pressures up to 15 MPa. Agreement among the laboratories was good up to 8 MPa. At the higher pressures, the data among the laboratories diverged significantly for two of the laboratories and coincided reasonably well for four of the laboratories. This work provides guidance for estimating the reproducibility that might be expected when comparing published sorption isotherms on moisture-equilibrated coals from different laboratories.

Authors:
Publication Date:
Research Org.:
National Energy Technology Laboratory (NETL), Pittsburgh, PA, and Morgantown, WV
Sponsoring Org.:
USDOE - Office of Fossil Energy (FE)
OSTI Identifier:
915491
Report Number(s):
DOE/NETL-IR-2007-151
TRN: US200817%%540
DOE Contract Number:
None cited
Resource Type:
Conference
Resource Relation:
Conference: 2007 International Coalbed Methane Symposium, Tuscaloosa, AL, May 21-25, 2007
Country of Publication:
United States
Language:
English
Subject:
01 COAL, LIGNITE, AND PEAT; 03 NATURAL GAS; CAPACITY; CARBON DIOXIDE; CARBON SEQUESTRATION; COAL; COAL DEPOSITS; COAL SEAMS; ILLINOIS; ISOTHERMS; METHANE; SORPTION; STORAGE

Citation Formats

Goodman, A.L.. CO2 Isotherms Measured on Moisture-Equilbrated Argonne Premium Coals at 550C and 15 Mpa. United States: N. p., 2007. Web.
Goodman, A.L.. CO2 Isotherms Measured on Moisture-Equilbrated Argonne Premium Coals at 550C and 15 Mpa. United States.
Goodman, A.L.. Tue . "CO2 Isotherms Measured on Moisture-Equilbrated Argonne Premium Coals at 550C and 15 Mpa". United States. doi:.
@article{osti_915491,
title = {CO2 Isotherms Measured on Moisture-Equilbrated Argonne Premium Coals at 550C and 15 Mpa},
author = {Goodman, A.L.},
abstractNote = {Sorption isotherms, which describe the coal’s gas storage capacity, are important for estimating the carbon sequestration potential of coal seams. The DOE-NETL initiated a second inter-laboratory isotherm comparison of coals where CO2 sorption isotherms were collected on moisture-equilibrated coals at temperatures and pressures relevant to CO2 sequestration. Each laboratory used the same coal samples and followed the same general procedure; however, each laboratory used their own apparatus and isotherm measurement technique. This study investigated the inter-laboratory reproducibility of carbon dioxide isotherm measurements on moisture-equilibrated Argonne premium coal samples (Pocahontas #3, Illinois #6, and Beulah Zap). Six independent laboratories provided isotherm data on the three moisture-equilibrated coal samples at 55oC and pressures up to 15 MPa. Agreement among the laboratories was good up to 8 MPa. At the higher pressures, the data among the laboratories diverged significantly for two of the laboratories and coincided reasonably well for four of the laboratories. This work provides guidance for estimating the reproducibility that might be expected when comparing published sorption isotherms on moisture-equilibrated coals from different laboratories.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue May 01 00:00:00 EDT 2007},
month = {Tue May 01 00:00:00 EDT 2007}
}

Conference:
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  • X-ray scattering techniques were used to gain a better understanding of the structural characteristics of the polynuclear aromatic hydrocarbons in coals. Carbon-carbon distances obtained from Radial Distribution Functions and Pair Correlation Functions agreed well with model distances. Two different calculations of n[sub cc], the average number of nearest neighbor carbons per carbon atom, gave comparable values. For the higher ranked coal an average value of 2.3 was calculated while for the lower carbon content coal, a value of 2.2 was obtained. These values were in the range expected for a substance composed of both aromatic and aliphatic linkages. Separation ofmore » the contributions from aromatic and aliphatic carbon-carbon distances to the first and second peaks in the Pair Correlation Functions showed the higher aromatic content of the higher ranked, higher carbon content coal. Comparison of the experimental data for the coals to model compounds using the Debye Equation showed that the maxima and minima of the experimental curves compared quite well, although the magnitudes did not.« less
  • A recent general model of coal pyrolysis proposed by the authors' research group has as one of its assumptions that the kinetics of primary product evolution are rank-insensitive. This assumption was tested by a thorough examination of data from experiments where only coal type was varied as well as data from similar experiments in the literature. The conclusion was that, with few exceptions, the kinetic rate constants show little variation with rank. However, this conclusion remains controversial. The Argonne premium samples provide an opportunity to further test this assumption with a set of coals that was designed to cover amore » wide range of coal types. A slow, constant heating rate experiment was used, which is the most sensitive to rate variations. A second controversial area is the importance of heating rate on the volatile product yield and distribution. Evidence has been presented which suggests no intrinsic effect of heating rate on pyrolysis yields and other studies have indicated the converse to be true. However, often these studies have been done under sufficiently different experimental conditions that direct comparisons are difficult. Work has indicated a role for heating rate on tar yields for bituminous coals and on tar molecular weight distributions for lignites. The authors plan to extend this work to the Argonne coals in order to better establish these trends. The current paper is concerned primarily with pyrolysis of the Argonne coals under slow heating conditions in a unique TG-FTIR instrument developed in this laboratory. Results from slow heating rate pyrolysis into a FIMS apparatus are also presented.« less
  • Infrared spectroscopy is a well-established method of coal characterization. Aspects of coal structure such as functional groups and hydrogen-bonding and changes in structure during pyrolysis and oxidation have been described through infrared analysis and related to macromolecular processes. In particular, Painter et al, have proposed an FTIR procedure for a fairly exhaustive analysis of coal functional groups. Many of these suggestions are incorporated into the present study for the development of a functional group analysis data base for a set of standard coals. Each of the two sampling methods employed here diffuse reflectance infrared (DRIFT) and KBr pellets, have advantagesmore » and drawbacks in coal analysis. DRIFT suffers from a lower signal-to-noise ratio, but is very sensitive to some infrared bands which do not appear well in transmission spectra. DRIFT is especially useful because coal can be sampled without an interfering matrix, which is important in determinations of OH and water content. KBr pellets, on the other hand, offer the advantages of a high signal-to-noise ratio and better control over sample concentration for quantitative work. The strengths of both methods have been exploited in this study.« less
  • The establishment of the Argonne Premium Sample Bank will allow more meaningful comparisons to be made between pyrolysis studies from different laboratories. This sample bank also provides a good suite of coals for examining rank dependent phenomena, such as the kinetics of primary gas evolution. A recent ''general'' model of coal pyrolysis proposed by our research group has as one of its assumptions that the kinetics of primary product evolution are rank-insensitive. This assumption was tested by a thorough examination of our data from experiments where only coal type was varied as well as data from similar experiments in themore » literature. The conclusion was that, with few exceptions, the kinetic rate constants for individual species evolved from coals pyrolyzed under the same conditions show little variation with rank. However, this conclusion remains controversial. The Argonne premium samples provide an opportunity to further test this assumption with a set of coals that was designed to cover a wide range of coal types. A slow, constant heating rate experiment was used, which is the most sensitive to rate variations. The authors' own work has indicated a role for heating rate on tar yields for bituminous coals and on tar molecular weight distributions for lignites. The authors plan to extend this work to the Argonne coals in order to better establish these trends. The current paper is concerned primarily with pyrolysis of the Argonne coals under slow heating conditions in a unique TG-FTIR instrument developed in the authors' laboratory. Results from slow heating rate pyrolysis into a FIMS apparatus are also presented. Experiments have also been done under rapid heating conditions.« less
  • The eight Argonne Premium coals were examined by using proton magnetic resonance thermal analysis (PMRTA). A new empirical parameter that is related to the second moment of the truncated frequency spectrum of the NMR signal is described and is used to quantify the fusion behavior of coal. The two lowest rank Argonne coals show the same fusion behavior as Australian brown coals of comparable atomic H-C ratios. The temperatures at which fusion of the Argonne bituminous coals occur are not significantly different from those of Australian coals of the same carbon content. However, the clear relationship found between the fusibilitymore » of Australian bituminous coals and hydrogen content is not observed for the Argonne coals. The enhanced fusibility of some of the Argonne Premium coals as compared to Australian coals with the same hydrogen content may be due to the higher sulfur content of those Argonne coals. 25 refs., 8 figs., 2 tabs.« less