Numerical Simulation and Industrial Experimental Research on the Coherent Jet with "CH4 + N2" Mixed Fuel Gas

Coherent jet technology is widely used in the electric arc furnace (EAF) steelmaking process to deliver more energy and momentum into the molten steel bath. Meanwhile, the characteristics of a coherent jet using pure CH₄ as the fuel gas have been well investigated in previous studies. To reduce the consumption of CH₄, coherent jet technology using "CH₄ + N₂" mixed fuel gas instead of pure CH₄ was proposed and studied in detail by numerical simulation in the present work. The Eddy Dissipation Concept model, which has detailed chemical kinetic mechanisms, was adopted to model the fuel gas combustion reactions. Experimental measurements were carried out to validate the accuracy of the computational model. The present study shows that the jet characteristics of the main oxygen improve along with the increase of the CH₄ ratio in fuel gas and with the increase of the flow rate of fuel gas. When the CH₄ ratio in the fuel gas is 25 pct, the fuel gas flow rate only has a limited influence on the jet characteristics, unlike the rest of the fuel gas compositions, because a high N₂ proportion deteriorates the combustion performance and leads to severe incomplete combustion. Moreover, a false potential core phenomenon was observed and explained in the present study. Based on the average values, the jet length of a coherent jet with 75 pct CH₄ can achieve 89.8 pct of that with 100 pct CH₄. Finally, an industrial experiment was carried out on a commercial 100t EAF using coherent jet with 75 pct CH₄, showing that the average CH₄ consumption was reduced from 3.84 to 3.05 Nm³ t^‑1 under the premise of no obvious changes in the other production indexes.