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金属学报  2020, Vol. 56 Issue (7): 1047-1056    DOI: 10.11900/0412.1961.2019.00344
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铝电解槽中局部阴极电流增大对电解质-铝液两相流场的影响
王富强1,2, 刘伟2, 王兆文1()
1.东北大学冶金学院 沈阳 110819
2.沈阳铝镁设计研究院有限公司 沈阳 110001
Effect of Local Cathode Current Increasing on Bath-Metal Two-Phase Flow Field in Aluminum Reduction Cells
WANG Fuqiang1,2, LIU Wei2, WANG Zhaowen1()
1. School of Metallurgy, Northeastern University, Shenyang 110819, China
2. Shenyang Aluminum and Magnesium Engineering and Research Institute Co. , Ltd. , Shenyang 110001, China
全文: PDF(2520 KB)   HTML
摘要: 

采用数值模拟方法建立了三维非稳态电解质-铝液两相流500 kA全槽模型,并通过铝液流速和电解质/铝液的界面变形测试数据验证了模型的准确性。在此基础上模拟并定量评估了6种实际电解生产中存在的局部阴极电流增大60%对铝液流场和界面变形产生的影响程度。结果表明,局部阴极电流增大并不能改变全槽的铝液流场和界面变形的整体趋势,只是局部位置的铝液流速和界面变形幅度略有差异,其中A2A3阴极电流增大有利于抑制B侧中部的界面隆起,极距平均改善幅度为3.0%。分别通过增大电解槽两端部,中部和A、B两侧的部分阴极电流比例对比分析了两相流场变化规律。结果表明,适当增加电解槽两端部的阴极电流有利于抑制界面变形,尤其是A1~A4和A21~A34阴极电流增加28%可将界面隆起最大值降低2.4 mm,B7~B18的极距平均拉高9.5%。该研究为母线优化和改善电解槽磁流体稳定性提供了一条新思路。

关键词 铝电解槽两相流场局部阴极电流增大界面变形数值模拟优化    
Abstract

The stability of the magnetohydrodynamics (MHD) of aluminum reduction cell is determined by the bath-metal two-phase flow field. So, konwing how to optimize the metal flow field and restrain the bath/metal interface deformation is the key to maintain the stable and efficient operation of cell. Many previous works on the bath-metal flow field are based on the static electromagnetic force stirring the melt, however, it should be have some deviation from the actual cell state. A three dimensional bath-metal two-phase quasi-steady flow model (based on transient electromagnetic force) for full 500 kA aluminum reduction cell was built by means of numerical simulation in this work, and validated by metal velocity and bath/metal interface deformation measurement in industrial cells. The effects of 60% increase of local cathode current on melt flow distribution and interface deformation were simulated and evaluated according to abnormal 6 cases in realistic electrolytic process. It was found that the increase of local cathode current has little effects on the general pattern of flow field and interface deformation in cell, but the amplitude of local metal velocity and interface deformation would be changed in certain extent. The increase of local cathode current in A2~A3 could decrease the interface height in middle cell of downstream side (side B), with anode cathode distance (ACD) increasing by 3.0%. But the other 5 cases could deteriorate the low ACD zone further in side B, especially the increase of local cathode current in A10A11, with average ACD decreasing by 4.6% in B12~B20. The solution is to cut cathode flexes partially in abnormal position to decrease the effect on the bath-metal two-phase flow. According to the evaluation results, it is found that the uneven distribution of cathode current may be helpful to decrease the interface deformation and improve the MHD stability of cell. Based on this finding, the bath-metal two-phase flow field was changed by increasing the proportion of cathode current at the two ends of cell, the middle part of cell and side A and side B respectively, and then was analyzed in this work. The simulation results show that it is beneficial to restrain the interface deformation by increasing the cathode current at both ends of cell properly, and it is also helpful to solve the cooling problem at cell ends. In particular, when the cathode currents at A1~A4 and A21~A24 increase by 28%, the distribution trend of melt flow field remains unchanged basically, and the maximum of metal velocity under A19~A20 increases by 10%, and the maximum of interface height decreases by 2.4 mm, and the average of ACD under B7~B18 increases by 9.5%. It provides a valuable reference for optimizing the busbar design and improving the cell MHD stability.

Key wordsaluminum reduction cell    two-phase flow field    local cathode current increase    interface deformation    numerical simulation    optimization
收稿日期: 2019-10-15     
ZTFLH:  TF821,O441.4  
基金资助:国家自然科学基金项目(51434005);国家自然科学基金项目(51529401)
通讯作者: 王兆文     E-mail: zhaowenw@mail.neu.edu.cn
Corresponding author: WANG Zhaowen     E-mail: zhaowenw@mail.neu.edu.cn
作者简介: 王富强,男,1981年生,教授级高级工程师,博士生

引用本文:

王富强, 刘伟, 王兆文. 铝电解槽中局部阴极电流增大对电解质-铝液两相流场的影响[J]. 金属学报, 2020, 56(7): 1047-1056.
Fuqiang WANG, Wei LIU, Zhaowen WANG. Effect of Local Cathode Current Increasing on Bath-Metal Two-Phase Flow Field in Aluminum Reduction Cells. Acta Metall Sin, 2020, 56(7): 1047-1056.

链接本文:

https://www.ams.org.cn/CN/10.11900/0412.1961.2019.00344      或      https://www.ams.org.cn/CN/Y2020/V56/I7/1047

Material

Density

kg·m-3

Viscosity

Pa·s

Conductivity

S·m-1

Bath2.13×1032.51×10-30.23×103
Metal2.30×1031.18×10-34.17×106
表1  物性参数
图1  电解质-铝液两相流物理模型
图2  正常槽况下铝液流速分布模拟结果
Range / mRatio / %
-0.05~-0.040.3
-0.04~-0.032.0
-0.03~-0.027.0
-0.02~-0.0121.8
-0.01~08.4
0~0.0123.9
0.01~0.0223.8
0.02~0.0312.8
0.03~0.040.1
表2  正常槽况下界面变形范围分布
图3  正常槽况下电解质/铝液界面变形模拟结果
图4  铝液流速测点位置及流速方向
图5  铝液流速模拟值与测试值对比
图6  界面变形的模拟值与测试值对比
CaseLocationMetal velocity / (m·s-1)Interface deformation / m
Max.Aver.Min.Max.
1A2A30.2150.064-0.0460.031
2A6A70.1840.068-0.0450.032
3A10A110.1840.072-0.0530.032
4A14A150.1790.071-0.0540.031
5A18A190.1990.067-0.0440.031
6A22A230.2060.067-0.0470.031
表3  6种不同槽况下两相流场的模拟结果对比
图7  局部阴极电流增大后的两相流场模拟结果
图8  A侧和B侧极距(ACD)变化幅度
CaseLocationCurrent increaseMetal velocity / (m·s-1)Interface deformation / m
%Max.Aver.Min.Max.
11AB: 1~4, 21~24100.2010.065-0.0450.030
12AB: 1~4, 21~24200.2090.064-0.0530.029
13AB: 5~2050.1770.067-0.0440.032
14B: 1~4, 21~24140.1910.067-0.0490.031
15B: 1~4, 21~24280.1960.067-0.0560.030
16B: 1~4, 21~24420.1970.067-0.0610.030
17A: 1~4, 21~24140.1970.065-0.0440.029
18A: 1~4, 21~24280.2070.063-0.0410.029
19A: 1~4, 21~24420.2150.061-0.0410.030
表4  9种对比槽况下两相流场的模拟结果汇总
图9  Case 11~case 19的B侧极距变化幅度
图10  Case 11、case 12和case 17~case 19的两相流场模拟结果
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