MATHEMATICAL MODELLING AND CONTROL OF THE BLAST FURNACE PROCESS

The objectives of this study have been: to develop a mathematical model for the blast furnace process and to implement its steady state simulation on a digital computer; to extend it into a dynamic simulation model; and to formulate and propose a detailed strategy for the optimization of the blast furnace operation. The first part of the study consists of the development of the mathematical model for the blast furnace process. For this purpose the process was divided into four major zones, each zone characterized by a different set of major reactions and process phenomena taking place within it. These were the stack, bosh, combustion zone and hearth. A kinetic model was developed for the stack and bosh zones of the furnace. The hearth zone kinetic model was based upon the assumption that chemical equilibrium is attained or closely approached for the two major reactions taking place there, the desulphurization and silica reduction reactions. For the combustion zone model, complete conversion of the reactants to carbon monoxide and hydrogen was assumed while transferring energy to the molten materials descending from the bosh to the hearth. The steady state simulation model was tested with data from two small capacity furnaces and two large capacity modern furnaces, with excellent results in each case thus confirming the validity of the basic model assumptions. The steady state simulation model was extended into a dynamic simulation model and a preliminary program was written. A detailed proposal for an optimization of the furnace operation at the bosh, combustion and hearth zone was formulated. The methodology for its possible implementation was selected and algorithms were developed and are presented in flow charts to facilitate this proposed work