Coal-fired power plants produce flue gas consisting mainly of nitrogen
(around 79%), followed by CO2 (around 10 – 15%), and small amounts of other
gases such as H2, NOx and SO2. One of the promising methods for reducing CO2
emission is CO2 sequestration into deep, unminable coal seams. At present, flue
gases exhausted from coal-fired plant must be separated to extract pure CO2
before injecting it into coal seams.
In order to enhance the efficiency of carbon capture and storage (CCS) from
a coal-fired power plant, oxy-fuel combustion technology has been employed.
This technology uses pure oxygen to burn the coal, and consequently CO2
concentration in the flue gas is theoretically increased up to 95%.
This study aims to simulate the CH4 replacement mechanism in coal by using
pure CO2 and a synthesized flue gas (99% CO2 and 1% SO2) that is similar to the
emission gas from the coal-fired power plants. A measurement procedure for gas
adsorption is employed which, after establishing methane adsorption equilibrium
of the coal samples, injects pure CO2 or the synthesized flue gas into an
adsorption cell in order to investigate CH4 replacement properties. Coal
samples used for the present experiments were taken from the coal seams of
Vietnam, Japan, Australia, China and Indonesia. The samples were crushed to
particle sizes ranging from 250 μm to 5 mm. The concentration of gases was
taken from the adsorption cell and analyzed by using a gas chromatograph.
Adsorption isotherms of CH4, CO2 and SO2 were measured by using the volumetric
This paper discusses the characteristics of methane replacement by using
pure CO2, the synthesized flue gas and the effect of SO2 on adsorption
properties of coal.
Global warming and climate change due to the greenhouse effect continue to
be a serious problem. In particular, CO2 emission into the atmosphere from
coal-fired power plants needs to be reduced. One of the most promising methods
of reducing CO2 emissions is CO2 sequestration in deep, unminable coal seams.
The CO2 adsorption capacities of coals were investigated by Huy et al.(1). The
results showed that CO2 adsorption was double that of CH4.
© 2009. Society of Petroleum Engineers
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- Original manuscript received:
31 March 2008
- Meeting paper published:
17 June 2008
- Revised manuscript received:
22 June 2009
- Manuscript approved:
22 June 2009