Enhanced Ladle Shroud Performance using a Novel Design Concept versus a Conventional Shroud Design

Abstract

The Ladle Shroud is an important device in Steelmaking, which aims to protect the deoxidized molten steel from re-oxidation by the atmosphere, prior to casting and solidification. A problem with current designs of ladle shrouds is the negative pressure developed at the upper joint connecting the top of the ladle shroud to the lower nozzle of the ladle. Possible air infiltration makes it essential to protect the said joint with argon shrouding, which in turn leads to a multiphase flow, and the likelihood of forming uncontrolled numbers of large argon gas bubbles. On exiting the ladle shroud, these argon bubbles de-couple from the liquid steel to form TOE's ("Tundish Open Eyes") within the overlaying slag layer protecting the steel from the atmosphere. Another problem is the turbulent, multi-phase, flow that is generated during start-up procedures. These can heavily re-oxidize the initial flows of liquid steel. Mathematical and physical water modelling are used in the present work, to propose and study a new Ladle Shroud design. The purpose of the new design is to avoid the negative pressure at the ladle shroud upper joint, to suppress the initial multiphase turbulent flow and to thereby generate microbubbles for the advanced cleaning of liquid steels. The performance of the newly converging-diverging design is compared with a standard reverse taper design. The simulations and experimental results comparing fluid flows between the two designs provide initial proof that the new design will bring improvements to ladle shroud performance.