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| Titel |
Methane and carbon dioxide adsorption capacity of bituminous coals from the Ostrava-Karvina Coal District, Upper Silesian Basin, Czech Republic |
| VerfasserIn |
P. Weniger, A. Busch, B. M. Krooss, Juraj Francu, E. Francu |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250023925
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| Zusammenfassung |
| In the context of a joint Czech-German project, experimental and analytical methods are
being applied to improve the understanding of compositional variation of coal-related
gas in the SW part of the Upper Silesian Basin (Czech Republic). According to
present understanding, the gas composition is controlled by generation (thermal vs.
microbial), migration and adsorption/desorption processes. In particular the effects of the
sorption processes on the chemical and isotopic composition of coal gases are only
poorly explored. During the first stage of this project, the gas adsorption capacity
has been determined for coal samples representing the paralic Ostrava Formation
(Namurian A) and the limnic Karviná Formation (Namurian B-C). For this purpose,
high pressure adsorption isotherms have been measured for methane and carbon
dioxide on medium and low volatile bituminous coal (VRr 1.2-1.8%) from the
production face of two collieries in the study area. Adsorption isotherms have been
measured for pressures up to 25 MPa for CO2 and up to 17 MPa for methane at
20Ë C and 45Ë C. Isotherms were measured on dry, moisture-equilibrated and
“as received” samples (moisture content: 0.5-1.7%, mineral-matter-free) using a
manometric method. Sorption capacities for CH4 at 45Ë C ranged from 18 to 27 Std.
cm3/g (0.7 to 1.1 mmol/g) coal, dry ash-free (daf), showing an increase of sorption
capacity with increasing coal rank. For CO2, sorption capacities were generally
higher than for methane, ranging from 35-40 Std. cm3/g (1.4-1.7 mmol/g) coal (daf).
Equilibrium moisture contents, determined by a modified ASTM method, were
significantly higher than the “as received” moisture. Sorption capacities measured on
moisture-equilibrated samples were generally lower than those measured on dry or “as
received” samples. Methane excess sorption isotherms show a type I Langmuir form and
could be approximated using the Langmuir function. Excess sorption isotherms for
CO2 show a decrease in the pressure region close to the critical point and require a
modified approximation that takes into account the density of the adsorbed phase.
Calculated density values for the adsorbed phase ranged between 1.1 and 1.2 g/cm3.
Results of the sorption experiments will be presented and discussed in the context
of coal rank and composition and in comparison with coals from other regions. |
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