Coarse-grained rCFD-DEM analysis of coke gasification and iron ore reduction in the shaft region of an ironmaking blast furnace

Abstract

Understanding the fundamentals of iron ore reduction and coke gasification in the shaft region of an ironmaking blast furnace (BF) is the key to improving iron productivity and stability, yet the particle-scale understanding is hindered by the huge computational cost. In this paper, a coarse-grained reacting CFD-DEM (rCFD-DEM) model is implemented to investigate the complex thermochemical behaviours inside a simplified BF shaft. The results show that, in comparison to the CFD-DEM approach, the coarse-grained rCFD-DEM approach can have a similar accuracy but reduces computational cost by ~89.01% in this study. The typical thermochemical behaviours in respective coke and iron ore layers can be captured at particle scale. Then the effect of key operating parameters is studied quantitatively at particle scale. It is indicated that the inlet velocity increasing from 1.7 m/s to 2.3 m/s improves the reduction degree of iron ore by 16%, but the coke consumption is reduced by 5.51%. The operating temperature increasing from 1200 K to 1250 K increases the coke consumption by 44.92%, but the reduction degree of iron ore only increases slightly. When CO mass fraction in the inlet gas increases from 0.25 to 0.30, the coke consumption increases by 12.68% and the reduction degree of iron ore increases by 16.88%. The findings shed light on the fundamentals of coke gasification and iron ore reduction in the BF shafts. • A coarse-grained reacting CFD-DEM model is developed to investigate the blast furnace shaft. • Compared to previous CFD-DEM approach, the approach have a similar accuracy but reduces computational cost by ~89%. • The typical thermochemical behaviours and the effect of key operating parameters are quantified. • The findings shed light on the fundamentals of coke gasification and iron ore reduction in blast furnace shafts.