Study On Attrition Mechanism Of Oxygen Carrier During Chemical Looping Combustion

In order to solve this problem,the current global world attaches great importance to controlling greenhouse gas emissions through the use of carbon capture technology,but the capture company has a high cost,which has been restricting the further development of carbon capture technology.Compared with traditional combustion methods,the oxygen carriers used in chemical chain combustion technology can provide lattice oxygen,which can achieve CO₂ by interacting with the fuel,thus preventing some gases such as N₂ in the air from diluting the CO₂ emitted in the flue gas The internal separation captures carbon dioxide from the root to achieve low energy consumption or even zero energy consumption.Oxygen carriers occupy an important position in this technology,and in-depth study of its potential properties is of great significance to the development of chemical chain combustion technology.Compared with other oxygen carriers,iron-based oxygen carriers have some advantages such as good thermodynamic properties,no pollution,abundant reserves and low price,which are evaluated as the best oxygen carriers for future industrial applications.However,iron-based oxygen carriers also have the common problems of poor attrition resistance and short lifetime of many oxygen carriers,which greatly limit the application in chemical chain combustion technology.In this thesis,we propose the application of fiber toughening technology to improve the attrition resistance of oxygen carriers based on fiber toughening ceramic material technology.The high purity Al₂O₃ fibers are used in the preparation of iron-based oxygen carriers by changing the fiber content and calcination temperature to obtain the oxygen carrier modification;the oxygen carriers are designed for attrition testing in a fluidized bed at 900°C with different fluidization air velocities.During the experiments,the mass of fines was collected to calculate the attrition rate and cumulative attrition rate,and the experimental data were fitted with Gwyn’s attrition kinetic equation,and the differences in attrition patterns of different particles could be described by the parameters of Gwyn’s equation,so as to investigate the attrition pattern of the oxygen carriers and evaluate the toughening effect of Al₂O₃fiber on iron-based oxygen carriers.Based on the experimental study,the change of CO conversion rate during cycling was analyzed,and the effect of fiber on the activity and morphology of the oxygen carrier was further explored by combining SEM,PSD and XRD characterization methods to reveal the mechanism of toughening.The results showed that the Al₂O₃ fibers effectively improved the mechanical strength and attrition resistance of Fe₂O₃/Al₂O₃ oxygenate carriers,and the mechanical strength and attrition resistance of the carriers increased with the increase of fiber content and calcination temperature,and to a certain extent,the reactivity of the carriers was improved.the results of the Gwyn attrition equation were consistent with the attrition characteristics of the oxygenate carriers under different working conditions.The characterization results show that the toughened oxygenates exhibit crack deflection and crack-linked bridges.The work in this thesis provides a new idea for improving the attrition resistance and lifetime of oxygenates,which has a positive effect on improving the lifetime of oxygenates.