THERMODYNAMIC ANALYSIS OF THE BLAST FURNACE PROCESS UNDER THE CONDITIONS OF TOP GAS RECIRCULATION AND HIGH OXYGEN ENRICHMENT OF THE BLAST

Abstract

The blast furnace process is the dominant technology in worldwide iron metallurgy. The basic fuel in this process is coke. However, coke production is associated with several adverse environmental impacts. The reduction of coke consumption in a blast furnace can be achieved by injection of auxiliary fuels or by changing the parameters of the blast. The recirculation of the top gas into the process after CO2 and H2O removal and the high enrichment of the blast with oxygen are considered to be future technologies conducive to the reduction of coke consumption. The paper presents the influence of the above-mentioned technologies on the operating parameters of the blast furnace plant. The simulation calculations were performed using the formulated theoretical-empirical mathematical model of the blast furnace plant. The mathematical model of the blast furnace is built based on the mass and energy balances of its separated temperature zones. The balances of the elements and also the energy balance equation have been set up separately for the top zone of heat transfer and the lower zone of production together with the thermal reserve zone. The balances of elements and the energy balance also for the tuyére zone have been applied. The advanced data validation and reconciliation method to eliminate incompatibilities of selected balances of mass and energy of the temperature zones of the blast furnace for the so-called basic measurement of its raw materials and energy consumption indicators in the steady-state of operation has been applied. The carried out simulation calculations showed a significant saving of coke in the process under top-gas recirculation after CO2 and H2O removal and oxygen enrichment of the blast conditions.