关键词: 石墨内衬, 多孔介质, 二氧化碳, 氧化扩散, 孔隙演化, 数学模型

Abstract: Based on the Fick's law and the law of conservation of mass, the mathematical model for the oxidation diffusion and the pore structure evolution of graphite liner under the rare earth molten salt electrolysis environment was established which included the effects of the oxidation reaction, the gas diffusion and the pore structure evolution. Under high carbon dioxide environment and high temperature, the graphite oxidation experiment was carried out. The CT technology were adopted to obtain the pore structure images which were then binarized and the porosity was calculated statistically. The calculated values of the porosity and weight loss rate of the cylindrical sample were compared with the experimental results. Then the oxidative corrosion process were simulated numerically. The results show that the reaction diffusion iand the evolution of the pore structure influnece each other significantly. In additon, the oxidation and diffusion of the graphite liner was greatly influenced by temperature. At higher temperature, the reaction runs faster, and the porosity becomes higher, as a result, the life of the tank is shorter. The calculation results of the model are consistent with the measured results, which indicates that it is feasible and efficent to use the model to calculate and analyze the oxidation and diffusion process of the graphite liner under the electrolytic environment.

Key words: graphite lining, porous media, carbon dioxide, oxidation diffusion, pore evolution, mathematical model