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-e 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. List of symbolsA inlet cross-sectional area of the nozzle at inlet, m 2 A slab cross-sectional area of the slab, m 2 C 1e ,C 2e ,C m constants in turbulence equations g acceleration owing to gravity, m s 22 G k generation of turbulent kinetic energy, Pa s 22 I turbulent intensity, % k turbulent kinetic energy, m 2 s 22 k in inlet turbulent kinetic energy, m 2 s 22 k p turbulent kinetic energy near the wall, m 2 s 22 n local coordinate normal to the wall p static pressure, N m 22 u i velocity in a particular direction, m s 21 v ref reference velocity, m s 21 v z,in SEN inlet velocity, m s 21 V resultant velocity, m s 21 V c casting speed, m min 21 y* dimensionless distance from the wall b effective area fraction of the port e turbulent kinetic energy dissipation rate, m 2 s 23 e in inlet turbulent kinetic energy dissipation rate, m 2 s 23 m dynamic viscosity, Pa s m t turbulent (eddy) viscosity, Pa s h local jet angle, deg. r density of liquid steel, kg m 23 s k ,s e constants in turbulence equations t w wall shear stress, Pa

Mathematical Analysis of the Dynamic Effects on the Deposition of Alumina Inclusions inside the Upper Tundish Nozzle

“…Furthermore, it has not been possible to find a material to simulate the particles that get attached on the acrylic walls as alumina inclusion does in the prototype walls. Even these limitations, the present deposition zones are in accordance with experimental works in plant previously reported, 35,36) as shown in Fig. 15.…”

Turbulent Flow Phenomena and Ce2O3 Behavior during a Steel Teeming Process

“…As reported by Uemura et al, 60) an inclusion that comes close to a nozzle wall sinters and forms a neck with the refractory of a nozzle wall or with an inclusion that already deposited on a nozzle wall. According to Sambasivam,30) the neck will be broken and the inclusion may be washed away when a shear stress at the neck is higher than the sinter bond strength. Therefore, in the regions with a high shear stress level, a deposition of an inclusion may be prevented even though the inclusion is present or moving close to the nozzle wall.…”

“…Furthermore, steel flows in nozzles were also studied and compared by using of different turbulence models. [30][31][32][33][34][35] Some researchers also studied the inclusion behavior in a nozzle during casting. Wilson et al 14) investigated the steel flow characteristics in a nozzle and tracked the trajectories of inclusions.…”

Study on the Fluid Flow in a Semi-Open-Stream-Poured Beam Blank Continuous Casting Mold with Submerged Refractory Funnels by Multiphase Modeling

“…Obviously, the maximum shear stress of the funnel with the 30 mm inner diameter is bigger than that with the 40 mm inner diameter in the chart. The average value of the 40 mm inner diameter case is 25.11 Pa, while the average value of the 30 mm inner diameter case is 64.48 Pa. Sambasivam [32] studied the effects of inner wall shear stress on avoiding inclusion build-up inside the nozzle. Sambasivam stated that relatively higher shear stress values can help in reducing the clogging tendency during the initial periods of inclusion build-up.…”