Numerical simulation of the effect of hydrogen injection and oxygen enrichment interaction on PCI in a blast furnace

Hydrogen displays the potential to partially replace pulverized coal injection (PCI) in the blast furnace, and it can reduce CO2 emissions. In this paper, a three-dimensional mathematical model of hydrogen and pulverized coal co-injection in blast furnace tuyere was established through numerical simulation, and the effect of hydrogen injection and oxygen enrichment interaction on pulverized coal combustion and raceway smelting was investigated. The simulation results indicate that when the coal injection rate decreased from 36 to 30 t/h and the hydrogen injection increased from 0 to 3600 m3/h, the CO2 emissions decreased from 1860 to 1551 kg/t, which represents a 16.6% reduction, and the pulverized coal burnout decreased from 70.1% to 63.7%. The heat released from hydrogen combustion can not only promote the volatilization of pulverized coal but also affect the combustion reaction between volatilization and oxygen, which resulted in a decrease in the temperature at the end of the raceway. Co-injection of hydrogen with PCI increased the wall temperature near the upper half part of the raceway and at the outlet of the tuyere, which required a high cooling efficiency to extend the service life of the blast furnace. The increase in oxygen level compensated for the decreased average temperature in the raceway due to hydrogen injection. The increase in the oxygen content by 3% while maintaining constant hydrogen and PCI injection rates increased the burnout and average raceway temperature by 4.2% and 43 K, respectively. The mole fraction of CO and H2 production increased by 0.04 and 0.02, respectively. Burnout can be improved through optimization of the particle size distribution of pulverized coal.