Solution behavior and pore structure evolution of coke under H2O+CO2 atmosphere
It is of great significance for investigating the corrosion and evolution of coke pore structures under H2O+CO2 atmospheres to understand the solution-loss and degradation behaviors of cokes in hydrogen-rich blast furnace.The solution-loss experiments of columnar cokes in the CO2,N2+20％H2O,and CO2+20％H2O atmospheres were carried out by a homemade coke reactivity measurement device with continuous water inflow.The characteris-tics of pore structure distribution in coke profiles were layer-by-layer detected by image analysis method combined with circular testing mode,and the evolution of coke pore structures during solution-loss process was studied on a three-dimensional scale.The results show that the pore structures of the columnar coke present a"cone-like"evolu-tion during the solution-loss reactions of coke under H2O+CO2 atmosphere.The H2O in the reaction atmosphere could shorten the reaction depth to the uneroded core of coke with the similar characteristics of pore distribution and weaken the diffusion depth of coke in the solution-loss reaction.The content of small pores in coke has a quadratic linear relationship with the reaction depth,and the path of the fitting quadratic equation(d)is proposed to charac-terize the degree of solution-loss evolution for coke pore structures.The H2O in the reaction atmosphere could lead to the decrease of the d value,which shows that the difference in pore structure between the inner and outer layers of coke increases.Moreover,the solution-loss volume ratio of carbon based on the solution-loss layer volume and re-activity of cokes is proposed to quantitatively characterize the diffusion depth of the coke in solution-loss reaction.The H2O in the reaction atmosphere could reduce the solution-loss volume ratio of carbon by 24.4％,and the pro-portion of uneroded core in coke increases by 9.78％.Therefore,the increase of H2O content in the reaction atmos-phere promotes the solution loss reactions on the surface of the coke,and water-gas reaction could weaken the deep reaction of the coke and enhance the degree of coke shrinkage.The research results can provide experimental and theoretical basis for deepening the understanding of solution-loss and degradation behaviors of cokes in hydrogen-rich blast furnace and improving the coke quality evaluation system.
cokepore structureH2O+CO2 atmospheresolution-loss reactionuneroded core of coke
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