Interaction Between Key Components Of Oxygen - Enriched Coal - Fired Flue Gas And Different Coal - Rank Coal

As the most anthropogenic greenhouse gas, carbon dioxide （CO₂） emissions causes a series of environmental issues. Thus, great efforts are needed to control CO₂ emissions. Hitherto, there are plenty options for CO₂ emissions control. Among them, Carbon dioxide Capture& Sequestration （CCS） is regarded as a promising method to mitigate CO₂ emissions. For the one hand, oxyfuel combustion is a promising option for capturing CO₂ emitted from coal-fired power plant. For the other hand, CO₂ sequestration in deep coal seams with enhanced coal-bed methane （CH4） recovery （CO₂-ECBM） can store the captured CO₂ in geologic period. Thus, if the coal-fired oxyfuel combustion flue gas directly sequestrated in deep coal seams is successfully implemented, the emissions of greenhouse gas （CO₂） and the main gaseous pollutants （NOX, SO₂） contained in flue gas will be simultaneously mitigated and CH4 as a by-product can also be recovered. In order to verify the feasibility of the coal-fired oxyfuel combustion flue gas sequestration in the deep coal seams, the interactions of NO and SO₂ with three coal samples （two bituminous coals and one anthracite） were elucidated in detail in this work.The main conclusions from this work are summarized as follows:（1） The fluid sequestration in the deep coal seams is mainly due to the strong adsorption performance of coal matrix. Therefore, the accurate determination of the high-pressure fluid adsorption performance of coals is meaningful to evaluate the fluid sequestration potential of the target coal seams. Thus, the error propagation theory was applied to analyze the influences of pressure, temperature, sample weight, cell volume and compressibility factor on the high-pressure adsorption test based on the volumetric method. The analysis results show that the pressure accounted for the main part of the total error, compared with other independent variables. The total errors of GSE increase with the equilibrium pressure and the partial errors of GSE also increase with the equilibrium pressure. Thus, the measured parameters including using higher precision pressure transducer, decreasing the volume of the sample cell and increasing the sample mass should be adopted to improve the accuracy.（2） The investigations on the interactions of NO with various rank coals confirm that Sips isotherm model can well describe the NO adsorption equilibrium behavior on various rank coals. The Elovich equation can fit NO adsorption kinetics on coals successfully. The Fourier Transform Infrared （FTIR） and X-ray photoelectron spectroscopy （XPS） characterization results further confirm that the chemisorption via formation of amine （-NH2） or amide （-CONH2） is the main interaction mechanism between NO and coals. Pyrrole/pyridone-N species contained in coals probably participate in the interaction between NO and various rank coals according to XPS analysis. The novel chemical interaction between NO and coals will not only benefit NO sequestration in coal seams, but also have potential to enhance the CO₂ storage performance of the target coal seams due to electron donor-acceptor mechanism.（3） With respect to the interactions of SO₂ with various rank coals, the experimental results show that the Freundlich isotherm model can used to predict SO₂ adsorption equilibrium behavior on various rank coals, and the pseudo-second order model exhibits well predictive accuracy of SO₂ adsorption kinetics on coals. The XPS further indicates that the chemisorption, i.e., the formation of sulphone is the main interaction mechanism existed between SO₂ and thiophene or sulphoxide contained in coals.