Clogging resistant submerged entry nozzle design through mathematical modelling

Abstract

Submerged entry nozzle (SEN) clogging is caused by deposition of solid microinclusions present in the liquid steel and aided by stagnation and swirling velocity regimes near the bottom wall. A mathematical model has been developed to investigate steel flow within the SEN and the results obtained with k–ϵ and Reynolds stress model (RSM) turbulence models have been compared. The existing flat SEN bottom causes stagnation of the steel flow within the nozzle and the absence of shear stress prevents the removal of inclusions. The jet from the port is narrow and focused and has two high turbulent swirls near the walls. As a remedy, a parabolic curve shaped bottom has been designed to guide the liquid steel flow and has resulted in a better flow profile and exit jet characteristics. Stagnation is absent and the jet characteristics have improved with the average jet turbulence being reduced by 33%. The study on the sufficiency of the shear stress magnitudes to remove clogging has shown that the curve bottom performs better compared with the flat bottom. The effect of casting speed variation has also been studied on these two bottom configurations. The preliminary plant trials show encouraging results.

Keywords:

• CLOGGING
• INCLUSIONS
• STAGNATION
• SEPARATION
• TURBULENCE