Bubble Formation from a Two-Hole Nozzle Attached to a Top Lance

Submerged powder injection is widely used for steel refining processes. Powder is usually injected downwards through a single-hole nozzle or horizontally through a two-hole nozzle attached to a top lance into the molten metal bath with carrier gas. In this study we investigate fundamentally horizontal injection through a two-hole nozzle to enhance the refining efficiency of the processes. As a first step, experimental investigation is carried out on the bubble formation from the two-hole nozzle in the case that only gas is injected into the bath. Two types of bubble formation patterns are observed depending on the gas flow rate: synchronized and non-synchronized bubble formations. A synchronization ratio is newly introduced in this study to describe the degree of synchronization. The frequency of bubble formation at each nozzle is measured with a high-speed video camera and compared with existing empirical equations for a single-hole nozzle because no empirical equation is available for the frequency of bubble formation for a two-hole nozzle.