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Some new aspects on inclusion separation in tundishes
Author(s) -
Javurek Mirko,
Kaufmann Bernhard,
Zuba Gerhard,
Gittler Philipp
Publication year - 2002
Publication title -
steel research
Language(s) - English
Resource type - Journals
eISSN - 1869-344X
pISSN - 0177-4832
DOI - 10.1002/srin.200200194
Subject(s) - particle (ecology) , mechanics , turbulence , chemistry , diffusion , buoyancy , thermodynamics , physics , geology , oceanography
The removal of non‐metallic inclusions due to buoyancy forces in tundishes in continuous casting systems is considered. The maximal theoretical removal rate is determined by the flow rate through the tundish, the magnitude of the tundish fluid surface area and the particle terminal rising velocity, depending on the particle size. Two reasons, why the particle separation is worse than the maximal possible one are an unsuitable fluid flow pattern and the turbulent particle diffusion. An analytical discussion of simple flow patterns (parallel flow with different velocity profiles, dead regions, swirling flows) and diffusion shows how they influence the particle removal. Using these simple considerations, it is demonstrated that the often used RTD (residence time distribution)‐curves are inappropriate to estimate the particle separation in tundishes; only the direct measurement and CFD‐simulation of particle removal should be used. The common CFD‐methods are affected with numerical errors such as numerical diffusion for particle concentration simulations with finite volume methods and interpolation errors for particle trajectory calculations. These errors influence significantly the calculated particle removal curves; they are non‐systematic and difficult to quantify.