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Modelling Approaches of Multiphase Phenomena Focusing on an Integrated Steelmaking Route

Time: Fri 2023-03-24 10.00

Location: Sefström, Brinellvägen 23, Stockholm

Video link:

Language: English

Subject area: Materials Science and Engineering

Doctoral student: Reza Safavi Nick , Processer

Opponent: Adjunkt Professor Stein Tore Johansen, SINTEF

Supervisor: Professor Pär Jönsson, Processer; Universitets lektor Björn Glaser, Processer; Professor Dong-Yuan Sheng, Processer

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Improvements in numerical methods and developments of computer hardware brought attention to the modelling of metallurgical processes. This has been a critical step in understanding in-furnace conditions throughout the ironmaking and steelmaking process since it is, if not impossible, extremely difficult to conduct measurements during the process.

With the introduction of mathematical models, attention has been on the computational fluid dynamics (CFD) modelling of each process to try to shed light on the furnaces’ interior operations. Moreover, most of these processes fall into the category of a multiphase system where different phases of material interact with each other. For example, in a blast furnace shaft, solid particles descend into the furnace while the blast pushes gas through the packed bed; during the desulphurization process, a powder material is injected into the hot metal by means of inert gas; in the ladle station, the steel cleanness is achieved by means of gas and/or induction stirring.

Each of these processes has been the focus of a number of studies where the processes have been modelled using different methods namely, fully Eulerian or Eulerian-Lagrangian methods mostly for solid-fluid systems and Volume-of-Fluid (VOF) or VOF-Lagrangian for liquid-liquid or liquid-gas systems. However, there have been fewer studies where the investigations focused on which of these methods is best fitted for a specific process and why. Thus, the current study has been trying to fill this gap to give an overview of the integrated steelmaking route modelling approaches with a focus on the usability of models in the frame of results and computational efforts for the industry.

This study goes through the integrated steelmaking route by looking at solid particles flow in the blast furnace, desulphurization of the hot metal produced by blast furnaces and the ladle refining process where a novel stirring strategy is introduced. Then, the focus turns on one of the most common by-products of the steelmaking process namely, the slag. This is due to the fact that the steelmaking slag contains a substantial amount of energy. However, there has been lesser effort in the utilization of such energy. The recent global greenhouse gas reduction initiative has brought significant attention to different aspects of steelmaking processes with respect to socio-economic development in combination with governmental policies. Hence, the study investigates the utilization of deposited energy within the steelmaking slag by means of a heat exchanger to answer the calls for a greener industry.

In the end, the current study recommended to use the Eulerian modelling approach to model solid-fluid interactions in a blast furnace and powder injection into a liquid bath in a sulphur refining station. Furthermore, it is suggested that it can be advantageous to use the Volume-of-Fluid modelling approach to model liquid-gas interactions during the ladle refining process. Finally, it is recommended to use the reduced single-phase model for the conjugate heat transfer mdoelling to predict the static liquid energy dissipation in a slag heat recovery station.