SIMULATION OF THE REDUCTION OF IRON-OXIDE POWDER BED BASED ON REACTIVITY OF CONSTITUENT POWDER AND DYNAMIC EFFECTIVE DIFFUSIVITY
1979 Volume 12 Issue 2 Pages 130-136
Details
1979 Volume 12 Issue 2 Pages 130-136
A procedure to predict macroscopic characteristics of solid-gas reactions on the basis of microscopic information on the reactivity of the powders composing the solid and the structure coefficients for gaseous transfer was proposed and applied to the reduction of an iron-oxide powder bed by hydrogen. This reaction example was consecutive and consisted of three stoichiometric reactions (Fe2O3→Fe3O4, Fe3O4→Fe1-y1O, and Fe1-y2O→Fe) and a nonstoichiometric reaction (continuous decrease in y of Fe1-yO).
Profiles of the fractional reduction, gaseous reactant concentration, and variation in pressure within the bed during the reaction were computed and compared with the experimental results. The width of the zone of each reaction, which cannot be predicted by the conventional unreactedcore shrinking model, was also demonstrated.
It was also found that the equilibrium hydrogen concentration for the reactions in the wustite range and wustite to iron became apparently high due to very slow change in the gas composition in the bed.
