CFD simulation of effect of anode configuration on gas-liquid flow and alumina transport process in an aluminum reduction cell

Abstract

Numerical simulations of gas-liquid two-phase flow and alumina transport process in an aluminum reduction cell were conducted to investigate the effects of anode configurations on the bath flow, gas volume fraction and alumina content distributions. An Euler-Euler two-fluid model was employed coupled with a species transport equation for alumina content. Three different anode configurations such as anode without a slot, anode with a longitudinal slot and anode with a transversal slot were studied in the simulation. The simulation results clearly show that the slots can reduce the bath velocity and promote the releasing of the anode gas, but can not contribute to the uniformity of the alumina content. Comparisons of the effects between the longitudinal and transversal slots indicate that the longitudinal slot is better in terms of gas-liquid flow but is disadvantageous for alumina mixing and transport process due to a decrease of anode gas under the anode bottom surface. It is demonstrated from the simulations that the mixing and transfer characteristics of alumina are controlled to great extent by the anode gas forces while the electromagnetic forces (EMFs) play the second role.

Keywords

aluminum reduction cell / anode configuration / gas-liquid flow / alumina transport process / simulation / alumina content distribution

References

[1] LiuY-x, LiJieModern aluminum electrolysis [M], 2008BeijingMetallurgical Industry Press69-77

[2] ZhouN-j, XueY-q, ChenJ J, TaylorM P. Numerical simulation of electrolyte two-phase flow induced by anode bubbles in an aluminum reduction cell [J]. Chemical Product and Process Modeling, 2007, 11(2): 1934-1945

[3] ZhouN-j, XiaX-x, WangF-qiang. Numerical simulation on electrolyte flow field in 156 kA drained aluminum reduction cells [J]. Journal of Central South University, 2007, 14(1): 42-46

[4] ZhangH-l, WangZ-g, LiJ, LaiY-qing. Simulation on flow field of anode gas and electrolyte in aluminum electrolysis with cermet inert anodes [J]. Journal of Central South University: Science and Technology, 2010, 41(4): 1256-1262

[5] ZhanS-q, ZhouJ-m, LiM, DongY, ZhouY-w, YangJ-hong. Numerical simulation of gas-liquid two-phase flow in aluminum reduction cells with perforated anodes [J]. CIESC Journal, 2013, 64(10): 3612-3619

[6] ZhanS-q, LiM, ZhouJ-m, YangJ-h, ZhouY-wen. A CFD-PBM coupled model predicting anodic bubble size distribution in aluminum reduction cells [C]// GOHN G. Light Metals 2014, 2014San DiegoTMS777-782

[7] DoheimM A, ElkershA M, AliM M. Computational modeling of flow in aluminum reduction cells due to gas bubbles and electromagnetic forces [J]. Metallurgical Materials Transactions B, 2007, 38(1): 113-119

[8] ZhangK-y, FengY-q, SchwarzP, WangZ-w, CookseyM A. Computational fluid dynamics^(CFD) modeling of bubble dynamics in the aluminum smelting process [J]. Industrial and Engineering Chemistry Research, 2013, 52(4): 11378-11390

[9] FengY Q, CookseyM A, SchwarzM PHagniA M. CFD modeling of alumina mixing in aluminium reduction cells [C]. Light Metals 2010, 2010Seattle, WATMS451-456

[10] FengY Q, CookseyM A, SchwarzM PLindsayJ. CFD modeling of alumina mixing in aluminium reduction cells [C]. Light Metals 2011, 2011San Diego, CATMS543-548

[11] ThomasHNumerical simulation and optimization of the alumina distribution in an aluminium electrolysis pot [D], 2011LausanneÉcole Polytechnique Fédérale de Lausanne

[12] ZhangH-huiNumerical study of vortex flow of melts and transport process of alumina in aluminum reduction cells [D], 2012ChangshaCentral South University

[13] KaenelR, AntilleJ, RomerioM V, BessonOBarryS. Impact of magnetohydrodynamic and bubbles driving forces on the alumina concentration in the bath of an Hall-Héroult cell [C]. Light Metals 2013, 2013San AntonioTMS585-590

[14] ZhanS-q, LiM, ZhouJ-m, ZhouY-w, YangJ-hong. Numerical simulation of alumina concentration distribution in the melts of aluminum reduction cells [J]. The Chinese Journal of Nonferrous Metals, 2014, 24(10): 2658-2667

[15] ZhanS-q, LiM, ZhouJ-m, YangJ-h, ZhouY-wen. CFD simulation of dissolution process of alumina in an aluminum reduction cell with two-particle phase population balance model [J]. Applied Thermal Engineering, 2014, 73(1): 803-816

[16] DiasH P, MouraR RKvandeH. The use of transversal slot anodes at ALBRAS melter [C]. Light Metals 2005, 2005San Francisco, CATMS341-344

[17] SeveroD S, GusbertiV, PintoE C V, MouroR RSorlieM. Modeling the bubble driven flow in the electrolyte as a tool for slotted anode design improvement [C]. Light Metals 2007, 2007Orlando, FLTMS287-292

[18] YangW, CookseyM ASorlieM. Effect of slot height and width on liquid flow in physical models of aluminum reduction cells [C]. Light Metals 2007, 2007Orlando, FLTMS451-456

[19] YangS, ZhangH-l, XuY-j, ZhangH-h, ZouZ, LiJ, LaiY-qing. Effects of slot cutting at prebaked anodes on bubble elimination in aluminum reduction cell [J]. Journal of Central South University: Science and Technology, 2012, 43(12): 4617-4625

[20] SatoY, SadatomiM, SekoguciK. Momentum and heat transfer in two-phase bubble flow-I: Theory [J]. Int J Multiphase Flow, 1975, 7(2): 167-177

[21] FLUENT Inc. Fluent 6.3 User’s Guide [EB/OL]. [2014-05-15]. http://aerojet.engr.ucdavis.edu/fluenthelp/html/ug/mainpre.htm.

[22] CookseyM A, YangWGpallowayT J. PIV measurements on physical models of aluminum reduction cells [C]. Light Metals 2006, 2006WarrendaleTMS359-365