Modelling on the Oxygen-Carbon Co-Injection with Supersonic Shrouding Jet in EAF Steelmaking

Supersonic gas–solid mixing jet is frequently encountered in the electric arc furnace to efficiently regulate foaming slag formation, accomplish carburization and melt of scrap due to its enhanced penetration depth. In the current work, a gas–powder nozzle with supersonic shrouding jet is numerically simulated via the discrete parcel method. After the proposed model being well verified with the experiment, the impact of solid flow rate (ranging from 6 to 24 kg/min) and powder diameter (ranging from 0.05 to 0.4 mm) on the compressible gas characteristics and particle behaviors are focused. The results show that the large interface zone between the jet core and the peripheral low-speed fluid enhances shearing effects, leading to faster velocity decay and reduced particle acceleration capability compared to a Laval nozzle. In addition, enlarging particle feeding rate from 6 to 24 kg/min significantly enhances momentum transfer from gas to particles, thereby limiting expansion capability, resulting in reduced gas velocity (from 382 m/s to 314 m/s at z/Z = 0.2), higher gas temperature (from 210 K to 234 K at z/Z = 0.2), and accelerated total pressure decay (3.13 × 10⁵ to 2.08 × 10⁵ Pa at z/Z = 0.2). In contrast, the impact of the particle size on gas flow is limited. Moreover, the transfers of energy and momentum between phases primarily hinge on the velocity disparities between them, predominantly transpiring within the jet core region prior to the axial position of z/Z = 0.2. Furthermore, increasing the particle feeding rate decreases particle velocity while raising particle temperature, while decreasing particle diameter enhances their ability to align with gas velocity and temperature. Finally, the high-velocity zone of particles can only be maintained within 1.2 m, properly adjusting the nozzle height is essential for ensuring jet penetration ability. The findings of current work provide valuable insights into the design of this kind of novel nozzle and the optimization of industrial operating parameters.