Mixing of concentric gas jets issuing vertically into a liquid

Mixing of two concentric jets of dissimilar gases blown vertically upward through wafer was investigated experimentally. Air was blown through the inner pipe and carbon dioxide through the annular space between the inner and the outer pipes. The two jets mixed rapidly upon emergence from the nozzle. This made physical shielding of the air jet by CO₂ ineffective. It was caused by the fact that the air bubbles during and upon emergence from the nozzle were large. Moreover, they exhibited oscillations which made them spread over the annulus. Pursuing this argument it has been inferred that physical shielding would be ineffective in OBM/Q-BOP converter process of steelmaking as well. Therefore, protection of tuyere lining by shrouding gas seems to be due to thermal and chemical shielding, primarily. N.B. BALLAL, formerly a Graduate Student at Indian Institute of Technology, Kanpur, is presently