Author(s)

J. A. Castro, A. W. S. Baltazar & A. J. Silva

Abstract

The blast furnace process is a counter current flow reactor whose main purpose is to produce hot metal. This process uses as auxiliary fuel the injection of pulverized coal through the equipment termed the tuyere. However the injection point in the tuyere is of summary importance for the complete combustion of the pulverized coal, which in turn will affect the smooth blast furnace operation. Recently, the price of premium coals became prohibitive for using in the blast furnace, especially in Brazil, where this raw material is imported. Therefore attempts have been made to allow the use of low quality coals partially substituting the premium coals decreasing the production cost of steels. This paper deals with the simulation of the pulverized injection of low-grade coals into the channel of the blast furnace raceway. The analysis was based on a 3D three phase mathematical model, where motion, heat transfer and chemical reactions among chemical species were calculated based on transport equations. Interactions among phases were computed with the help of semi-empirical correlations. The chemical kinetics rates were adapted from the literature by adjusting the constants for representing the industrial process. The finite volume method implemented in a complex computational code written in Fortran 90 was used to solve the highly non-linear system of partial differential equations in a non-orthogonal mesh representing the geometry of a tuyere with different injection points. The comparison between model results for temperature and gas composition and experimental/industrial showed very close agreement. The mathematical model proved to be useful to predict the effect of the injection of different quality coals in the raceway and an efficient tool to evaluate new raw materials for the blast furnace Keywords: mathematical modelling, pulverized coal and multiphase flow.

Keywords

mathematical modelling, pulverized coal and multiphase flow.