Molecular Dynamics Study On Dissolution-loss Reaction Mechanism Of Coke

The dissolution-loss reaction of coke in blast furnace is closely related to the strength of coke,which directly affects the permeability of blast furnace,the ratio of coal injection and the quality of molten iron.It is the key factor affecting the operation efficiency of blast furnace.Therefore,it is of great significance to further explore the dissolution-loss reaction of coke in the blast furnace.Pingyao coke was selected as the sample,and the dissolution-loss reaction mechanism of coke in CO₂ atmosphere was studied at the molecular level through the method of particle coke reaction experiment and theoretical calculation.Through the characterization of gaseous product and solid residue,the change of coke microstructure was analyzed.The results of SEM show that the structure of reacted coke is seriously damaged,the pore wall is corroded,collapsed seriously,even produces cracks.The XRD results show that the size and stacked thickness of the crystallite increase.The results of XPS show the proportion of graphite carbon in the solid residue increase and the graphitization degree increase.The Reax FF kinetic method was used to simulate the coke dissolution-loss reaction process in CO₂ atmosphere,and the overall variation trend of the system simulated by Reax FF was consistent with the experimental results.The main path of carbon layer reconstruction and CO generation was obtained by using C++program to analyze the Reax FF simulated trajectories.DFT was used to calculate the energy of the reaction path.The results show that the oxidation of carbon layer by CO₂ molecules is the rate-controlling step of coke dissolution-loss reaction.The activation energies of carbon layers with different folding degrees show that the carbon atoms in the larger folded carbon layers have lower activation energies,and are more likely to react with CO₂ to form defects,thus reconstructing into flat carbon layers.So graphitization of the folded carbon layer is the essential reason for the decrease of coke strength,which establishes the essential relationship between the coke strength and the dissolution-loss reaction.These results explain the obvious difference of activation energy in the dissolution-loss reaction of different coke samples in the experiment and reveal the mechanism of the dissolution-loss of coke from the molecular level.Figure 44;Table 1;Reference 90...