Flow Characteristic of Supersonic Jet Related to O2–CO2 Mixing Injection Method

The O 2 –CO 2 mixing injection method was proposed to mitigate CO 2 emissions and enhance the CO content in flue gas during the BOF steelmaking process. Despite the reported advantages of the O 2 –CO 2 mixing injection method, limited research existed regarding the impact of Laval nozzle structures designed by various CO 2 mixing rates on the flow characteristics of supersonic mixing jets. In this research, we investigated four types of Laval nozzle structures designed for varying CO 2 mixing rates through a series of experimental tests and numerical simulations. The results indicated that when the CO 2 additional flow rate increased from 0 to 15 mass pct, the impaction ability of the mixing jet enhanced. However, this increasing rate was gradually suppressed due to the thermo-physical property variations between O 2 and CO 2 . Under room and high ambient temperature conditions, the average axial velocity variation within the velocity potential core was 1.58 and 1.68 m/(s·mass pct), respectively. To further validate the metallurgical effects, a pilot test was conducted using a 1.0 ton converter with O 2 and CO 2 blowing rates of 210 and 31.5 Nm 3 /h, respectively, demonstrating that the Laval nozzle structure designed based on the O 2 –CO 2 mixing gas thermo-physical property could achieve superior metallurgical outcomes.