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Numerical and physical modelling of tundish slag entrainment in the steelmaking process
Thesis (MEng)--Stellenbosch University, 2015.
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Stellenbosch : Stellenbosch University
2015
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| _version_ | 1867614046920900608 |
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| access_status_str | Open Access |
| author | Mabentsela, Arthur |
| author2 | Akdogan, G. |
| author_browse | Akdogan, G. Mabentsela, Arthur |
| author_facet | Akdogan, G. Mabentsela, Arthur |
| author_sort | Mabentsela, Arthur |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MEng)--Stellenbosch University, 2015. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/97972 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:45:48.703Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2015 |
| publishDateRange | 2015 |
| publishDateSort | 2015 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/97972 Numerical and physical modelling of tundish slag entrainment in the steelmaking process Mabentsela, Arthur Akdogan, G. Bradshaw, S. M. Stellenbosch University. Faculty of Engineering. Dept. of Process Engineering. Tundish -- Bare Tundish -- Flow control device Tundish slag entrainment -- Modelling Steelmaking UCTD Thesis (MEng)--Stellenbosch University, 2015. ENGLISH ABSTRACT: Extensive work has been published in the open literature concerning the flow patterns in bare tundishes and tundishes furnished with flow control devices. However, very little work has been published on the entrainment of tundish slag. The aim of this research was to study (physically and numerically) tundish slag behaviour in a bare tundish and a tundish furnished with a flow control device (FCD). Furthermore, to identify, if any, the mechanisms for tundish slag entrainment in a bare tundish and a tundish fitted with a flow control device and to make recommendations based on the findings of this study. The physical modelling was done in a 1:2 reduced scale model of an industrial tundish such as was studied by Kumar et al. (2008). In the physical model, water was used to model the steel phase while paraffin was used to model tundish slag. The numerical modelling was done in ANSYS Fluent 14.5. The Volume of Fluid (VOF) model was used to model the interface between the two phases (paraffin and water). Turbulence was modelling by making use of the Realizable k- ɛ model. Observations made whilst the model was running showed that the steel-slag interface remains immobile even in the FCD case. Furthermore entrained paraffin formed small droplets, approximately 1 mm in diameter. These droplets could be seen in small numbers throughout the tundish. Results from the physical model showed that in both the bare tundish and tundish with a FCD, areas of high concentrations of entrained slag exist near the inlet region. The entrained slag concentration decreases towards the tundish end walls. A numerical model that can be used to model tundish slag behaviour was developed using the VOF model with a mesh size of 1.4 mm at a time step of 0.125 s for the bare tundish and a tundish fitted with a FCD. The model predicted similar entrained slag patterns as those of the physical model. Analysis of flow patterns and velocity magnitudes tangential to the steel-slag interface showed that slag entrainment in both the bare tundish and tundish with a flow control device possibly takes place via two mechanisms. First the slag moves across the steel-slag interface via mass transfer, secondly small velocities tangential to the interface, 3 x 10-³ m/s for the bare tundish and 1.5 x 10-² m/s for the FCD case, at depth of greater than 10 mm below the interface carry the already “entrained” slag into the bulk steel phase. These tangential flow patterns are dominant in the inlet shroud and are to be found in both the bare tundish and in the tundish with a FCD, hence the high concentration of entrained slag in this region. AFRIKAANSE OPSOMMING: Baie studies is al in die literatuur publiseer omtrent die vloeipatrone in eenvoudige verdeeltrog en in verdeeltrog met vloei-beheer toestelle (VBT). Min werk is egter al gedoen oor die saamsleep van die metaalskuim in verdeeltrog. Die doel met hierdie studie is om die fisiese en numeriese gedrag van die metaalskuim in eenvoudige verdeeltrog en in verdeeltrog met VBT te bestudeer en om die meganismes, as hulle wel bestaan, vir die saamsleping van metaalskuim in eenvoudige verdeeltrogs, asook in verdeeltrogs met VBT te identifiseer en om dan aanbevelings te maak. Die fisiese modellering is met ’n 1:2 skaalmodel van die industriële skottel wat deur Kumar et al.(2008) bestudeer is, gedoen. In die fisiese model is water gebruik om die staalfase te modelleer terwyl paraffien gebruik is om die verdeeltrog se metaalskuim te modelleer. Die numeriese modellering is in ANSYS Fluent 14.5 gedoen. Die volume van vloei (VOF) model is gebruik om die twee fases (paraffien and water) te modelleer. Die standaard massa en momentum vergelykings is met die gebruik van die Realizable k- ɛ model opgelos. Deur waarneming terwyl die model aan die loop was, is vasgestel dat die staal-metaalskuim koppelvlak immobiel bly selfs in die geval van VTB. Verder het die saamgeleepte paraffien klein druppeltjies van 1 mm gevorm. Resultate van die fisiese model toon dat daar beide in die geval van die eenvoudige verdeeltrog en die verdeeltrog met VTB areas met hoë konsentrasies by die inlope is, Die saamgesleepte metaalskuim neem naby die skottel se eindwande af. ’n Numeriese model wat gebruik kan word vir die modellering van die metaalskuim gedrag is ontwikkel. Hiervoor is die VOF model met ’n sel grootte van 1.4 mm teen ’n tydstap van 0.125 s vir beide die eenvoudige verdeeltrog en die verdeeltrog met ’n VBT gebruik . Hierdie model het dieselfde saamgesleepte metaalskuim patrone as die fisiese model voorspel. Ontleding van die vloeipatrone en spoed tangensiaal tot die staal-metaalskuim koppelvlak toon dat die samesleeping van metaalskuim in beide die eenvoudige skottel en die verdeeltrog met VBT op twee maniere plaasvind. Eerstens vloei die metaalskuim deur middel van massa oordrag oor die staal-metaalskuim koppelvlak, dan dra klein bewegende, 3 x10-³ m/s vir die eenvoudige verdeeltrog en 1.5 x10-² m/s vir die verdeeltrog met ’n VBT stroompies tangensiaal tot die koppelvlak op ’n diepte van 10 mm onder die koppelvlak die reeds saamgesleepte metaalskuim in die massa staal fase in. Hierdie tangensiale vloeipatrone is in die inloop area in beide die eenvoudige verdeeltrog en die verdeeltrog met die VBT dominant. Daarom is daar ’n hoë konsentrasi saamgesleepte metaalskuim in hierdie oppervlakte. Masters 2015-12-14T07:43:29Z 2015-12-14T07:43:29Z 2015-12 Thesis http://hdl.handle.net/10019.1/97972 en_ZA Stellenbosch University 97 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Tundish -- Bare Tundish -- Flow control device Tundish slag entrainment -- Modelling Steelmaking UCTD Mabentsela, Arthur Numerical and physical modelling of tundish slag entrainment in the steelmaking process |
| title | Numerical and physical modelling of tundish slag entrainment in the steelmaking process |
| title_full | Numerical and physical modelling of tundish slag entrainment in the steelmaking process |
| title_fullStr | Numerical and physical modelling of tundish slag entrainment in the steelmaking process |
| title_full_unstemmed | Numerical and physical modelling of tundish slag entrainment in the steelmaking process |
| title_short | Numerical and physical modelling of tundish slag entrainment in the steelmaking process |
| title_sort | numerical and physical modelling of tundish slag entrainment in the steelmaking process |
| topic | Tundish -- Bare Tundish -- Flow control device Tundish slag entrainment -- Modelling Steelmaking UCTD |
| url | http://hdl.handle.net/10019.1/97972 |
| work_keys_str_mv | AT mabentselaarthur numericalandphysicalmodellingoftundishslagentrainmentinthesteelmakingprocess |