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Civil-Comp Proceedings
ISSN 1759-3433 CCP: 76
PROCEEDINGS OF THE THIRD INTERNATIONAL CONFERENCE ON ENGINEERING COMPUTATIONAL TECHNOLOGY Edited by: B.H.V. Topping and Z. Bittnar
Paper 29
Analysis of Three Dimensional MHD flows in an Electric Furnace J.L. Xia+ and T. Ahokainen*
+Laboratory of Materials Processing & Powder Metallurgy, Helsinki University of Technology, Espoo, Finland
Full Bibliographic Reference for this paper
J.L. Xia, T. Ahokainen, "Analysis of Three Dimensional MHD flows in an Electric Furnace", in B.H.V. Topping, Z. Bittnar, (Editors), "Proceedings of the Third International Conference on Engineering Computational Technology", Civil-Comp Press, Stirlingshire, UK, Paper 29, 2002. doi:10.4203/ccp.76.29
Keywords: MHD flows, slag, electrode, three-dimensional, electric furnace.
Summary
In slag cleaning furnaces, electrodes are immersed into the slag bath. In such a device
the electric current not only generates heat in the slag but also a magnetic field. The
current interacts with this self-induced field to produce body forces within the bath and
the energy released by the electrodes leads to a temperature difference in the slag which
will lead to thermal buoyancy forces in the vertical direction that resist the
electromagnetic effects, although the latter is relatively small for large-scale furnaces.
Recently, attention has been increasingly paid to understand magnetohydraudynamic
(MHD) flows in metallurgical processes [1,2,3].
In the present paper, a three-dimensional mathematical model has been developed to
simulate the flow and heat transfer in a slag cleaning furnace. The MHD model has been
implemented into the CFX4 code [4] using user subroutines. Turbulence in the slag is
modeled by the standard
The physical model considered is an industrial-scale slag cleaning furnace. The
furnace is equipped with three electrodes that are located symmetrically and are
immersed half way into the slag. The furnace is of cylinder with inside diameter of
Boundary conditions are as follows: at walls the no-slip boundary conditions are
imposed for the momentum transfer and the standard logarithmic wall treatment is used.
The typical temperature of the sidewall is set at a constant
Here ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() The boundary conditions for the electric potential are as follows: the furnace wall is assumed insulated. At the bottom slag-matte interface the electric potential is set a value close to zero. The normal gradient of the electric potential is assumed to be zero at the free surface of slag. The electric potential on all surfaces of the electrode is presumed to be uniform.
The CFX4.3 [4] was utilized to solve the governing equations. A non-uniform mesh
(
With the MHD model implemented into the CFX4 code [4], we simulated three-dimensional flow and heat transfer in a slag cleaning furnace. The main conclusions can be drawn from the present investigation: The flow of the slag is quite complex and three-dimensional. The strongest flow appears near the electrode surface. In the bulk region the change of the slag temperature with the azimuth and radius is not great, and the highest slag temperature is around the electrode surface.
The electric potential drops sharply near the electrode. About 40% of the electric
potential drops within a region of about Most of heat released by the electrode is around the electrode surface, and the heat generation decreases rapidly away from the electrode. The highest heat generation is at the corner of the electrode tip.
The slag temperature increases with increasing the electric potential. Predicted slag
temperature is well agreed with the plant data measured in an actual operating furnace.
For the cases considered, the most appropriate range of the electric potential is between
References
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