Font Size: a A A

Marangoni Convection Transfer Characteristics Of Bath/Metal Interface In Aluminum Reduction Cell

Posted on:2014-10-04Degree:MasterType:Thesis
Country:ChinaCandidate:W X LuoFull Text:PDF
GTID:2251330425972649Subject:Power Engineering and Engineering Thermophysics
Abstract/Summary:PDF Full Text Request
Aluminum reduction cell plays a very important role in aluminum smelting process, its operating performance reflects the technological level of the aluminum smelting industry. The tank melt flow in industrial practice, is an important criterion to judge the performance of aluminum reduction cell. It is very important both in theories and practices to build an reasonable and reliable tank melt flow and mass transfer model which can be help to discrible and understand melt pad flow, metal/bath interface and mass transfer of liquid aluminium in bath layer. Nowdays Numerical research on the aluminum smelting process, have been used to instruct the reform and innovation of aluminum production, which could result in great improvement of the technology of the simulation and optimization of cells as well as rapid progress in alulninum business to achieve further energy saving target.This paper is funded by the National Natural Science Foundation project-"research on a two-layer fluid Marangoni convective transfer characteristics in magnetic field". The current domestic and international research about aluminum tank flow does not take gradient of interfacial tension of metal/bath into account and lack enough qualitative research on Mass Transfer. This paper developed a high precision model to analyze aluminum electrolytic tank melt flow and real mass transfer in industrial scale. Through this model, we can explore the liquid aluminum diffusion mechanism and influencing factors. The main innovation and research results are as follows:(1) An steady-state two-phase (metal-bath) model has been built up for modeling aluminum reduction cell molten flow and global metal/bath interface deformation. Computing the steady state of a175kA series aluminum electrolytic slot flow field, the results show that the flow of aluminum reduction cell at different heights slice come to an agreement; the velocity vector of the four silce emerged as the two axes of symmetry Maelstrom-the left side of the maelstrom is counterclockwise, the right is clockwise; addition, close to the TE side, the DE side and the middle of the furnace wall position exist many small whirlpool.(2) Based on the mechanism of loss of dissolved aluminum tank analysis, combined with the multiphase flow mass transfer mechanism, established the melt flow field of aluminum liquid mass transport model, and figured out the aluminum concentration distribution in ACD area. The application of this model to a175kA series industrial aluminum cell, could help understanding the molten aluminum dissolution process in ACD area. The results show that, due to regional differences in industrial tank melt flow and turbulent diffusion rate, before the whole area reached saturation, the aluminum concentration of the power-in side is much bigger than power-out side. The Convection Diffusion almost determine the concentration distribution of the liquid aluminum.(3) Specific to the previous aluminum reduction cell flow field model ignoring the gradient of the surface tension of the liquid metal/bath interface, this paper establishes the aluminum electrolytic tank Marangoni convective mass transfer mathematical model, focusing on the Marangoni convection melting body movement. The calculation results show that the Marangoni convection occur in aluminum electrolytic cell is not in the dominant position, the magnitude of the melt flow rate driven by Marangoni convection is10-3m/s, but the aluminum electrolytic tank with the actual flow rate of the order of magnitude10-1m/s. So the flow driven by the Marangoni convection can be neglected in aluminum cell. But the Marangoni convection could significantly increase the mass transfer coefficient of the liquid aluminum.(4) This article compares the mass transfer of liquid aluminum and the melt flow in different magnetic field. Found by calculating the BX, BY, BZ has little effect on the melt flow rate; reduced BZ will increase the undulations of molten metal/bath interface. Molten aluminum mass transfer coefficient is obviously affected by magnetic fields.
Keywords/Search Tags:aluminum reduction cell, melt movement, aluminumconcentration distribution, numerical simulation, two-phase flow
PDF Full Text Request
Related items