水素還元過程における酸化鉄単一球内の圧力増加と温度降下

抄録

A sample sphere of hematite, 3.3 cm in diameter, was reduced by H₂ and the variations of pressure and temperature within the sphere were continuously measured. At a reduction temperature of 895°C, the pressure and the temperature at the center of the sphere became 116 mmHg higher and 23°C lower respectively than those in the ambience. The variations of the pressure increase and the temperature fall were simulated according to the unreacted-core shrinking model with 3 reaction interfaces using a concept of the dynamic effective diffusivity. The calculated results were consistent well with the experimental results and the following conclusions were obtained.
1) The variations of pressure and temperature within the sphere reflected the progress of the reduction steps of Fe₂O₃ and gave useful information for the analysis of the consecutive reaction proceeding with multiple reaction interfaces.
2) The effect of the pressure increase on the overall reduction rate was considered to be remarkable, because the rate calculated on the isobaric assumption was much faster than the experimental one.
3) The difference in temperature between the center and the ambience of the sphere was not so large that the calculated results for isothermal and non-isothermal conditions gave almost the same overall reduction rate.