University of Oulu

Modelling of open-eye formation and mixing phenomena in a gas-stirred ladle for different operating parameters

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Author: Ramasetti, Eshwar Kumar1,2
Organizations: 1University of Oulu Graduate School
2University of Oulu, Faculty of Technology, Process Engineering
Format: ebook
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 10 MB)
Persistent link: http://urn.fi/urn:isbn:9789526223568
Language: English
Published: Oulu : University of Oulu, 2019
Publish Date: 2019-10-15
Thesis type: Doctoral Dissertation
Defence Note: Academic dissertation to be presented, with the assent of the Doctoral Training Committee of Technology and Natural Sciences of the University of Oulu, for public defence in the Arina auditorium (TA105), Linnanmaa, on 25 October 2019, at 12 noon
Tutor: Professor Timo Fabritius
Doctor Petri Sulasalmi
Doctor Ville-Valtteri Visuri
Reviewer: Professor Yaowei Yu
Associate Professor Karl Mickael Erik Ersson
Opponent: Docent Mikko Ilmari Helle
Description:

Abstract

In ladle metallurgy, gas stirring and the behaviour of the slag layer are very important for alloying and the homogenization of the steel. When gas is injected through a nozzle located at the bottom of the ladle into the metal bath, the gas jet exiting the nozzle breaks up into gas bubbles. The rising bubbles break the slag layer and create an open-eye. The size of the open-eye is very important as the efficiency of the metal-slag reactions depend on the interaction between the slag and steel created during the stirring process, and information about the position and size of the open-eye is important for effective alloying practice. Moreover, the open-eye has an effect on the energy balance since it increases heat losses.

In this study, experimental measurements and numerical simulations were performed to study the effect of different operating parameters on the formation of the open-eye and mixing time in a water model and industrial ladle. Experimental measurements were performed to study the effect of the gas flow rate, slag layer thickness, slag layer densities and number of porous plugs in a 1/5 scale water model and in a 150-ton steelmaking ladle. For numerical modelling, a multi-phase volume of fluid (VOF) model was used to simulate the system including the behaviour of the slag layer. The numerical simulation of the open-eye size and mixing time was found to be in good agreement with the experimental data obtained from the water model and data obtained from the industrial measurements.

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Tiivistelmä

Senkkametallurgiassa kaasuhuuhtelu ja kuonakerroksen käyttäytyminen ovat tärkeitä teräksen seostamisen ja homogenisoinnin näkökulmasta. Senkan pohjalla sijaitsevasta suuttimesta puhallettava kaasu hajoaa kupliksi, jotka rikkovat kuonakerroksen ja muodostavat avoimen silmäkkeen. Avoimen silmäkkeen koko on yhteydessä voimakkaampaan kuonan emulgoitumiseen, joka tehostaa metallisulan ja kuonan välisiä reaktioita. Tietoa avoimen silmäkkeen paikasta ja koosta tarvitaan myös tehokkaaseen seostuspraktiikkaan. Avoin silmäke vaikuttaa lisäksi prosessin energiataseeseen lisäten sen lämpöhäviöitä.

Tässä tutkimuksessa tutkittiin kokeellisesti ja laskennallisesti erilaisten operointiparametrien vaikutusta avoimen silmäkkeen muodostumiseen vesimallissa ja terässenkassateollisessa senkassa. Kokeellisia mittauksia tehtiin kaasuhuuhtelun, kuonakerroksen paksuuden, ja suuttimien määrän vaikutuksen tutkimiseksi 1/5-mittakaavan vesimallissa ja 150 tonnin terässenkassa. Numeerisessa mallinnuksessa systeemin ja siihen lukeutuvan kuonakerroksen käyttäytymisen simuloimiseen käytettiin volume of fluid (VOF) –monifaasimenetelmää. Avoimen silmäkkeen kokoon ja sekoittumisaikaan liittyvien numeeristen simulointien havaittiin vastaavan hyvin vesimallista ja teollisista mittauksista saatua kokeellista aineistoa.

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Osajulkaisut / Original papers

Osajulkaisut eivät sisälly väitöskirjan elektroniseen versioon / Original papers are not included in the electronic version of the dissertation.

  1. Ramasetti, E.K., Visuri, V.-V., Sulasalmi, P., Kärnä, A., & Fabritius, T. (2017). Numerical study of multiphase flows in a ladle for different closure models. Proceedings of the 11th Pacific Symposium on Flow Visualization and Image Processing, Kumamoto University, Kumamoto, Japan. http://jultika.oulu.fi/Record/nbnfi-fe2019082225151

  2. Ramasetti, E.K., Visuri, V.-V., Sulasalmi, P., & Fabritius, T. (2018). A CFD and experimental investigation of slag eye in gas stirred ladle. Journal of Fluid Flow, Heat and Mass Transfer, 5, 78-86. 10.11159/jffhmt.2018.008

    Rinnakkaistallennettu versio / Self-archived version

  3. Ramasetti, E.K., Visuri, V.-V., Sulasalmi, P., Mattila, R., & Fabritius, T. (2019). Modeling of the effect of the gas flow rate on the fluid flow and open-eye formation in a water model of a steelmaking ladle. Steel Research International, 90(2), 1-15. https://doi.org/10.1002/srin.201800365

    Rinnakkaistallennettu versio / Self-archived version

  4. Ramasetti, E.K., Visuri, V.-V., Sulasalmi, P., Gupta, A.K., Palovaara, T., & Fabritius, T. (2019). Physical and CFD modelling of the effect of top layer properties on the formation of open-eye in gas-stirred ladles with single and dual-plugs. Steel Research International, 1900088, 1-13. https://doi.org/10.1002/srin.201900088

    Rinnakkaistallennettu versio / Self-archived version

  5. Ramasetti, E.K., Visuri, V.-V., Sulasalmi, P., Savolainen, J., Li, M., Shao, L., & Fabritius, T. (2019). Numerical modelling of the influence of argon flow rate and slag layer height on open-eye formation in a 150-ton steelmaking ladle. Metals, 9(10), 1048. https://doi.org/10.3390/met9101048

    Rinnakkaistallennettu versio / Self-archived version

  6. Ramasetti, E.K., Visuri, V.-V., Sulasalmi, P., Fabritius, T., Saatio, T., Li, M., & Shao, L. (2019). Numerical modeling of open-eye formation and mixing time in argon stirred industrial ladle. Metals, 9(8), 829. https://doi.org/10.3390/met9080829

    Rinnakkaistallennettu versio / Self-archived version

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Series: Acta Universitatis Ouluensis. C, Technica
ISSN: 0355-3213
ISSN-E: 1796-2226
ISSN-L: 0355-3213
ISBN: 978-952-62-2356-8
ISBN Print: 978-952-62-2355-1
Issue: 712
Type of Publication: G5 Doctoral dissertation (articles)
Field of Science: 215 Chemical engineering
Subjects:
Copyright information: © University of Oulu, 2019. This publication is copyrighted. You may download, display and print it for your own personal use. Commercial use is prohibited.