Numerical modeling of reaction and flow characteristics in a blast furnace with consideration of layered burden

Abstract

A blast furnace process is applied to produce liquid pig iron that is suitable for subsequent refining to steel in an iron-making process. Increases in the productivity and reliability of the operation have been largely due to an enhanced understanding of the complicated physical and chemical phenomena in the furnace. However, methods such as a direct inspection and measurements of an actual furnace are limited, and conceptual descriptions and interpretive suggestions can supplement the working ideas of the complex phenomena inside the furnace. Computational modeling based on a mathematical formulation of the fundamental physico-chemical processes can significantly enhance the level of understanding by providing insight on the elementary steps of the process. A blast furnace can be modeled in a similar approach using a counter-current bed reactor. The objective of this study is to present a numerical model for predicting the shape of cohesive zone and predict operation condition such as pressure and temperature in a blast furnace. Description of physical processes of flow, heat transfer, mass conservation with chemical reaction inevitably requires simplification. First simplification is related with the geometry. Although the blast furnace is characteristically 3-dimensional in nature, 2-dimensional axi-symmetry will be assumed for simplicity while not sacrificing the significance of the physics. Also, time variation is not allowed, so that only the steady-state is considered. It is assumed that only two phases (solid and gas phases) exist in the furnace. Material composition in the solid phase includes coke, limestone and iron ore which changes it s own chemical state from $Fe_2O_3$, $Fe_3O_4$, $Fe_wO$ and Fe. Gas phase materials include CO, $CO_2$, $H_2$, $H_2O$ and $N_2$. Blast furnace is considered as a layer of solid bed whose components are homogeneously distributed. This would enable to consider the solid bed as a continuum, so that discretization is p...