Modelling and simulation of coke and PCI conbustion in an industrial blast furnace raceway

Abstract

The blast furnace, characterized as a countercurrent metallurgical reactor, is the most used process for the production of primary iron, pig iron, in the world. Inside it, iron ore and fluxes react with each other, forming liquid pig iron and slag through reactions with the gases that come from the combustion of coke, the main fuel source used in the process. As an indispensable material in the production of chemical energy of the furnace, coke becomes an important factor in the process, directly interfering both in the final composition of the pig iron and in the final cost of the equipment. With this in mind, the pulverized coal injection process comes as an alternative already used by most of the iron and steelmaking industries in reducing costs with coke. To understand this complex process, which involves chemical reactions, heat transfer, phase transformation, and flow at high temperatures and velocities, Computational Fluid Dynamics, a consolidated method of simulating engineering problems, has a solid base in the analyzes of all the blast furnace chain production, acting as a tool capable of assisting the predictability of this complex equipment. In this study, validations of the raceway formation, combustion of coke, and pulverized coal were studied and simulated using experimental and numerical data from the literature. The commercial software ANSYS-FLUENT was used to solve the conservation equations that govern the problem. The combustion models were simulated using kinetic reaction rates that considered the particle's internal structure. The validations presented acceptable results from an engineering view of point. In the end, the validated models were tested together using blast furnace operating conditions taken from a literature study that used a model similar to the one in the present work. The study will cover the reaction rates, temperature fields, flow fields, particle behavior during combustion, and chemical species produced and consumed during the process.