Application of the Reactions Concerning H₂ and Steam and the Temperature of Top Gas to the Blast-Furnace Model

Abstract

The over-all reaction rate Eq. (8) of the reaction between cokes and steam is derived, considering the steps of the diffusion through a gaseous film, intraparticle diffusion and chemical reaction. Considering that the rate of reaction between CO and steam is very fast and that gas flow is almost completely turbulent in the blast furnace, it has been assumed that the equilibrium of this reaction holds in the gas phase in the blast furnace. The over-all reduction rate of the iron oxide with hydrogen is given as Eq. (6), neglecting the effect of adsorption of water vapor.
Our model⁽³⁾ reported already has been modified here by addition of three reactions mentioned above and the boundary conditions of our new model have been calculated by means of the over-all heat and material balances and operating conditions.
Using this improved model, the axial distributions of temperatures of gas and particles, volume rate of flow of gas, compositions of CO, CO₂ and H₂, fractional conversions of iron and of limestone, density of gas, bulk density of particles and gaseous pressure under practical operating conditions in the blast furnaces have been determined numerically by a disital computer. The calculated results are illustrated in Figs. 4 and 5.
It has been confirmed that the calculated results agree well with the values reported by Shürmann⁽¹⁸⁾.