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| Author(s): |
Fabia Bocayuva Carvalho
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Escola Politécnica (EP/BC) |
| Defense date: | 2021-12-02 |
| Examining board members: |
Roberto Guardani;
Dirceu Noriler;
Tiago Ramos Ribeiro
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| Advisor: | Roberto Guardani |
| Abstract | |
Gas agitated systems are of great importance for industry in general, with a number of relevant industrial applications among which is metal refining, in systems involving the adjustment of composition through the interaction between gas and molten metal. Besides promoting homogenization of the temperature and composition of the molten metal, gas injection is also used for chemical reactions and the elimination of unwanted chemical compounds. In vacuum degassing of molten steel, the argon gas injected into the system is responsible for removing hydrogen and nitrogen present in the metal. These gases cause harmful effects to the quality of the final product, affecting its resistance and product life. Despite their relatively simple operation, bubble columns present complex and not fully understood flow patterns. In the present case, where the liquid phase consists of a molten metal at high temperatures, other limitations exist to the study of the process, such as temperature conditions and difficulties related to sample collection and flow visualization. In this case, Computational Fluid Dynamics (CFD) modeling is a powerful tool to simulate the multiphase flow involved in the process. The present study aims to develop a numerical model for the treatment of molten steel by vacuum degassing using CFD technique as a means for studying the distribution of the interfacial area and the concentration of gases in the steel. The effects of different process conditions on process efficiency, velocity and pressure profiles were investigated by implementing the Euler-Euler multiphase model, - turbulence model with BIT contributions from Troshko-Hassan and Simonin-Viollet models, and mass transfer model with adding correlation of Besagni et. al (2018) for the exchange interfacial area. The velocity field was accurately predicted in regions far from the gas injector for both BIT models, however, neither model showed significant improvement in accuracy over the standard - model. The Simonin-Viollet model was shown to be highly dependent on the values of its coefficient. The Besagni et. al (2018) correlation in the mass transfer model was shown to have a positive effect on the accuracy of the model, 98.86% compared to 93.65% for the initial model. (AU) | |
| FAPESP's process: | 19/08850-0 - Development of fluid dynamics model for bubble column reactors: application in a vacuum degassing system for liquid metal treatment |
| Grantee: | Fabia Bocayuva Carvalho |
| Support Opportunities: | Scholarships in Brazil - Master |