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| Titel |
Competitive sorption of CO2 and CH4 on coals as a function of maturity and moisture content |
| VerfasserIn |
Alexej Merkel, Yves Gensterblum, Bernhard Kroos, Ralf Littke |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250079854
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| Zusammenfassung |
| The competitive sorption of CH4 and CO2 from a two-component gas mixture on coals of
different rank and moisture content has been studied at pressures up to 10 MPa. The aim of
this study was to assess, the maximum sorption capacity as well as the selectivity of dry and
moisturised coals of different rank with respect to sorption of CH4and CO2. The research
addresses possible implications on Enhanced Coal Bed Methane (ECBM) recovery
projects, where CO2is to be injected into coal seams to increase CH4production
rates.
The measurements were conducted using a manometric setup with continuous pressure
and temperature recording and periodic analysis of gas compositions in the reference cell and
the measuring cell throughout the duration of the experiment. Isotherms were determined
with a gas mixture containing 70-80% CH4. Three isotherms were measured at three different
moisture states for each of the three coal samples of different rank. A significant
decrease of total excess sorption capacity was observed with increasing moisture
content from the dry sample to the sample moisturised at 53% relative humidity
(RH). The initial reduction of sorption capacity decreases with rank. Only a small
further decrease occurred from 53% to the 97% RH moisturised coals. The effect of
moisture on sorption capacity and selectivity is highly rank-dependent. In all cases the
results show a preferential sorption of CO2from a binary CH4/CO2gas mixture
at all three moisture states. Sorption capacity increases with rank for all but the
dry state and in all cases the sample with the highest maturity shows the highest
sorption capacity by far. Selectivity for CO2 decreases with increasing rank of the
coal.
The results of this study support that from the thermodynamic point of view coals have a
tendency to selectively take up CO2under the conditions of ECBM recovery. The selectivity
coefficients are important parameters for ECBM modelling and the design of production
strategies. |
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