Coal-fired power plants are producing flue gas including almost of Nitrogen (around 79%), next is Carbon dioxide (around 10 -15%), and small amount of others gases such as H2, NOx, SO2. One of the promising methods to reduce CO2 emission is the CO2 sequestration into deep un-mineable coal seams. Presently, the flue gas exhausted from coal-fired plant must be separated to get pure CO2 before injecting into coal seams.
In order to enhance the efficient of Carbon Capture and Storage (CCS) from coal-fired power plant, the oxyfuel combustion technology has been expected. This technology using pure oxygen to combust the coals, therefore, CO2 concentration in the flue gas is increased up to 95% theoretically.
This study aimed at characterizing CH4 replacement mechanism in coal by using pure CO2 and a synthesis flue gas (99% CO2 and 1% SO2) that is similar with emission gas from the plants. A measurement procedure for gas adsorption is that after getting methane adsorption equilibrium of the coal samples, pure CO2 or the synthesis flue gas is injected into an adsorption cell in order to investigate CH4 replacement properties. Coal samples used for present experiments were taken from coal seam No 9D, Maokhe coal mine, Vietnam. It was crushed with the size from 250 µm to 2mm. 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 method apparatus.
The characteristics of methane replacement by using pure CO2, the synthesis flue gas and effect of SO2 on adsorption properties of coal have been discussed in this paper.
Global warming and climate change due to greenhouse effect are continuing serious. Especially, CO2 emission into atmosphere from coal-fired power plants should be reduced than that of. One of the most promising methods to reduce the CO2 emission is CO2 sequestration in deep un-minable coal seams. CO2 adsorption capacity of some Vietnam coals were investigated by P.Q.HUY et al. (2006). Its CO2 adsorption is twice higher than that of CH4. Injecting CO2 into coal seams also produces methane by replacement mechanism using Enhanced Coalbed Methane method (ECBM).
Coal-fire power plants are producing flue gas including almost Nitrogen (around 79%), next is Carbon dioxide (around 10 to 15%), and small amount of other gases such as H2, NOx, SO2. Presently, the flue gas exhausted from coal-fired plant must be separated to get pure CO2 before injecting into coal seams. Normally, the technologies for CO2 separation from flue gas including physical adsorption, chemical adsorption, cryogenic distillation and membrane separation. Those technologies are much costly and complicated. So that, oxyfuel combustion technology has been expected in order to enhance the efficient of Carbon Capture and Storage (CCS) from coalfired power plant. This technology using pure oxygen to combust the coals, therefore, CO2 concentration in the flue gas is increased up to 95% theoretically.
Many researchers are focusing on applying the oxyfuel combustion technology into coal-fired power plant and the method to get CO2 with high concentration.