Abstract
As typical reaction models used in the analysis of gaseous reduction of porous iron-oxide pellet, the unreacted-core model, intermediate model, parallel model, and homogeneous-reaction model are noticed. The intermediate model in which the distribution of reduction degree in the reaction zone is neglected is useful to know the effect of gas penetration into the unreacted-core, since the model gives an analytical solution. The parallel model which allows the parallel proceeding of the chemical reaction and gaseous diffusion in the reaction zone is the most adequate one for actual conditions, though analytical solution could not be obtained. However, if Thiele's modulus φ defined as r0 [3kc (1+1/K)(1-ε0)/(reDe, 0)] 1/2 is more than 20, the same type of equation to the unreacted-core model could be applied approximately. In the case of very large intraparticle diffusivity, the homogeneous-reaction model is to be realized, but it is to be considered that the applicability of the model is very scarce as far as the shell and core structure exist.
