Numerical simulation of effect of interaction between hydrogen injection and oxygen enrichment on PCI of blast furnace

Hydrogen has the potential to partially replace pulverized coal injection (PCI) in the blast furnace, and can also reduce CO2 emissions. In this paper, a three-dimensional mathematical model of hydrogen and pulverized coal co-injection in blast furnace tuyere is established by numerical simulation, and the effect of hydrogen injection and oxygen enrichment interaction on pulverized coal combustion and raceway smelting is studied. The simulation results show that the coal ratio decreases from 36 to 30 t/h with the increase of hydrogen injection from 0 to 3600 Nm3/h. CO2 emissions decreased from 1860 to 1551 kg/t, representing an 16.6% reduction, the pulverized coal burnout decreased from 70.1% to 63.7%. The heat released from hydrogen combustion can promote the volatilization of pulverized coal, but also affect the combustion reaction between volatilization and oxygen, resulting in a decrease in the temperature at the end of the raceway. Co-injection of hydrogen with PCI increases the wall temperature near the upper half part of the raceway and at the outlet of the tuyere, demanding a higher cooling efficiency to extend the service life of the blast furnace. Increasing oxygen compensates for the decrease in average temperature in the raceway due to hydrogen injection. Increasing the oxygen content by 3%, keeping constants hydrogen and PCI injection rates, increases the burnout and average raceway temperature by 4.2% and 43 K, respectively. The mole fraction of CO and H2 production is increased by 0.04 and 0.02, respectively. The burnout can be improved by optimizing the particle size distribution of pulverized coal.