Improved Mathematical Model for Estimating Process Variables in Blast Furnace

Abstract

On the basis of the experimental data reported by other investigators^(11)(14), over-all reaction rates of the reduction of SiO₂ in slag and of the water gas shift reaction are determined as a function of operating conditions and these rates are used in a mathematical model.
As shown in Eqs. (18)∼(38), the specific heat of each component of burden materials is represented as a function of temperature and these equations are used in this model.
Longitudinal distributions of process variables are determined with the aid of a computer, and in this calculation fractional utilization of H₂ and fractional reduction of iron ores at the top of the bed in the blast furnace are considered. Fractional utilization of H₂ at the top of the bed exerts influence on the distribution of molar fraction of H₂ but the distributions of the other variables are not so much influenced by this factor.
Heat transfer coefficients determined from different empirical equations for the packed bed and for the solid particle are used in this model, and the calculated results on the longitudinal distributions of process variables under the same operating conditions are compared. Longitudinal distributions of overall reaction rates in the blast furnace are also discussed.