Dimensionless Groups on a Countercurrent Reduction of Iron Ore
The reduction of iron are particles is a gas-solid reaction and therefore the unreacted core modelis often applied. Material balances on a unit surface area are calculated in bothgas and solid phases.The residence time of are is normalized by a theoretical reducing time, and it isnamed Ot. Thecontact time of reducing gas is also normalized by a theoretical contact time, and it is named Gc. These two dimensionless groups Ot and Gc are very advantageous to understand the phenomena incountercurrent reductions.
Utilization coefficient diagrams are calculated by these two dimensionless parameters. These diagramsare shown by three variables, these are the reduction temperature, are sort, and reducing gas species.Other conditions, such as the gas flow rate, reducing gas fraction, are size, are weight on the bed, descending speed of ore, reaction rate constant, and so on are included in the two parameters. Bycalculating Gc and Ot from some conditions in the countercurrent reduction, the utilization coefficient and final reduction degree are decided from one of these diagrams.
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