Optimization of top gas recycling conditions under high oxygen enrichment in the blast furnace

Abstract

Primary steelmaking is among the most energy intensive industrial processes in the world and being mainly coal-based it substantially contributes to the global fossil CO2 emissions. It is therefore important to study potential ways of suppressing the use of fossil reductants and the rate of emissions in the process. This paper analyzes by simulation and optimization the concept of recycling CO2-stripped top gas in the blast furnace under massive oxygen enrichment, and its impact on the production economy and emissions of the steel plant. The effect of CO2 emissions and stripping/storage costs on the optimal states is presented. The system studied is demonstrated to exhibit complex transitions between the optimal states. The findings throw light on the importance of selecting a proper state of operation for achieving a cost-efficient production of steel with reduced environmental impact. © 2010 ISIJ.