Modelagem e simulação computacional da injeção de carvão pulverizado no canal adutor da “raceway” de altos-fornos

Abstract

The blast furnace 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 tuyere. Recently, the price of premium coals became prohibitive for using in the blast furnace, especially in Brazil, where this raw material is imported. The analysis was based on a 3D multi phase mathematical model. Three phases are considered in this model, namely, gaseous phase and two solid phases of pulverized coals. It was analyzed a high volatile and low volatile pulverized coal into different configurations of injection lances. The pulverized coal phases are considered separately pursuing velocity fields, temperature and the chemical composition. The chemical kinetics rates were adapted from literature and eventually the rate constants were adjusted for representing the individual reactivity of the pulverized coal. The numerical solutions of the highly non-linear system of differential equations were obtained in a computational code written in Fortran 90/95, based on finite volume method. Nonorthogonal mesh was used to representing the geometry of experimental apparatus and the raceway channel. The model was validated against experimental results and afterwards was used to simulate the injection of two pulverized coals into the raceway. The comparison between model results for temperature and gas composition and experimental/industrial data showed very close agreement. The mathematical model proved to be useful to predict the effect of injection of different coal types in the raceway and an efficient tool to evaluate new raw materials for the blast furnace.

Key words: Blast furnace, ironmaking, tuyeres, Pulverized coal injection, mathematical modeling, computational simulation.