Bubble formation by argon injection through the down-leg snorkel with Ruhrstahl–Heraeus (RH) circulating flow

Abstract

The objective for bubble refining is to control the production of plentiful, tiny and dispersed bubbles. For this, the rapid downward stream in the down-leg snorkel of an RH vessel can separate the injected gas into fine bubbles. In this work, the formation behavior of bubbles generated by argon injection through the down-leg is investigated by combining physical simulation experiments and multiphase flow simulations. A physical model was first established to investigate the formation behavior of argon bubbles. A Volume of Fluid model (VOF) was then developed and the results from the physical simulation used to validate the mathematical model. Subsequently, the validated VOF model was expanded to include the prediction of bubble formation behavior in liquid steel. From the results obtained, it was found that with a wetting orifice, separated bubbles are obtained under most conditions. When the orifice is non-wettable, the injected gas forms a curtain. When the separated bubbles are carried down into the ladle, they can be compressed to 70 % of their initial value, which enhances collision, promotes adherence to inclusions and facilitates their removal.