Fluid Dynamics Analysis of Coherent Jet with a Mixed Shrouding H2-CO2/N2 for EAF Steelmaking

In order to suppress the rapid combustion effect and consumption rate of pure hydrogen gas, N2 or CO2 at flow rates of 0, 80, and 240 Nm3/h was pre-mixed with shrouding H2 at flow rates of 800, 720, and 560 Nm3/h at room temperature, and the behaviors of the main oxygen jet and shrouding flame were analyzed by both numerical simulation and combustion experiments. The results showed that, because of the participation of CO2 in the H2 combustion reaction, the length of the axial velocity potential core was reduced using the CO2 shrouding mixed injection method, compared to the same mixed rate of N2. This trend would be further enhanced as N2 and CO2 mixing ratio increased. Meanwhile, when the shrouding mixed rate is 30%, the maximum axial and radial expansion rate generated by N2-H2 shrouding method is 1.28 and 1.04 times longer than that by the CO2-H2 shrouding method. The Fo-a, theoretical impaction depth and area generated by the 10% N2 shrouding mixed rate was 84.0, 95.5 and 86.4% of those generated by the traditional coherent jet, respectively, which indicated that the 10% N2 shrouding mixed rate method might lead to comparable production indexes in the EAF steelmaking process.