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Acta Metall Sin  2020, Vol. 56 Issue (7): 929-936    DOI: 10.11900/0412.1961.2020.00024
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Online Electromagnetic Measurement of Molten Zinc Surface Velocity in Hot Galvanized Process
ZHENG Jincan, LIU Runcong(), WANG Xiaodong()
Center of Materials Science and Optoelectronics Engineering, College of Materials Science and Opto-Electronic Technology, University of Chinese Academy of Sciences, Beijing 100049, China
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Abstract  

The behavior of zinc flow in the zinc bath plays an important role in hot galvanizing process, which has an important influence on the temperature distribution, the composition of zinc coat, the control of air knife, and so on, thus affecting the surface quality of zinc products (surface oxidation, rake slag). However, due to the high temperature, strong activity, opacification of the zinc bath and harsh, complex industrial environment, it is difficult to directly measure the flow behavior of zinc in the zinc bath through conventional methods. In this work, based on the principle of electromagnetic induction, Lorentz force velocimetry (LFV) method was used to measure and analyze the velocity of zinc flow in the bath during the galvanizing process for the first time. The LFV has the characteristics and advantages of non-contact, online and continuous measurement, and can realize the real-time quantitative measurement of molten metal flow by reasonable design and ingenious implementation. The key parameters of LFV, such as the gap between device and molten zinc, penetration depth and geometry of the applied model, were discussed through numerical analysis, the LFV device suitable for the characteristics of zinc plating process was designed, and the in-plant measurement was carried out. The results show that the fluctuation range of zinc flow velocity in the zinc bath is almost 0.13~0.20 m/s, which is within typical range referenced in previous studies. In addition, the flow behavior and flow field characteristics of zinc liquid were analyzed, and these discussions reflect the capacity of zinc slag or ash in the zinc flow at the monitoring position. The work promoted in this study revealed that this LFV method can measure the surface velocity of zinc liquid in real time, on-line and quantitatively, which provides a new way for the velocity monitoring of high temperature liquid metal in metallurgical industry.

Key words:  hot galvanized      zinc bath      molten zinc flow velocity      electromagnetic induction      Lorentz force velocimetry     
Received:  16 January 2020     
ZTFLH:  TG115.9  
Fund: Institute Collaborative Innovation Fund of University of Chinese Academy of Sciences(111800XX62)
Corresponding Authors:  LIU Runcong,WANG Xiaodong     E-mail:  liuruncong@ucas.ac.cn;xiaodong.wang@ucas.ac.cn

Cite this article: 

ZHENG Jincan, LIU Runcong, WANG Xiaodong. Online Electromagnetic Measurement of Molten Zinc Surface Velocity in Hot Galvanized Process. Acta Metall Sin, 2020, 56(7): 929-936.

URL: 

https://www.ams.org.cn/EN/10.11900/0412.1961.2020.00024     OR     https://www.ams.org.cn/EN/Y2020/V56/I7/929

Fig.1  Application principle of Lorentz force velocimetry (LFV) (Due to the distribution of magnetic field (B0) in the flowing molten metal, eddy current generated by electromagnetic induction between magnetic field and the molten metal, the Lorentz force (Fl) which brakes the molten metal is produced by the induction between the eddy current and the moving liquid (with the velocity of v), and the permanent magnet (PM) is also subjected to a force (Fm) in the same magnitude and the opposite direction)
Fig.2  Schematic of LFV device (1—support, 2—force sensor, 3—insulation coating, 4—magnet system)
Fig.3  Measurement schematic of molten zinc flow (top view) (I, II, III, IV and V are the test positions; Δx—distance between the two adjacent positions, Δy—distance between the test position and side of the zinc bath; Z+ and Z- are the outward and inward directions of galvanized sheet, respectively)
Fig.4  Schematic of numerical model (The zinc plate (length a, width a and thickness δ) is placed directly below the LFV device with a gap of h, its velocity is vs, and the distance between PM and outer bottom of the LFV device is ζ. P1~P4 represent different center positions of LFV device in numerical simulation)
Fig.5  Effect of δ on calibration results during numerical calculation
Fig.6  Effect of a on calibration results during numerical calculation
Fig.7  Effect of relative position between the LFV device and zinc plate on the results during numerical calculation (The horizontal ordinate x=Δy12a, the longitudinal coordinates y=fxfx=6×100%, in which fx is the Lorentz force with different positions at x=Δy12a)
Fig.8  Effect of relative position between the LFV device and zinc plate on distribution of induced eddy current density (j)
(a) position P1 (b) position P2 (c) position P3 (d) position P4
Fig.9  Numerical calculation data and calibration curve of the relationship between Lorentz force (Fs) and vs of zinc plate during numerical calculation
Fig.10  Measurement experiment of molten zinc flow
(a) industry measurement positions (I~V represent the center positions of LFV device above the zinc bath respectively, while the device is on the position I in this photo, as shown in Fig.3, Δx=30 mm, Δy=200 mm, and h=50 mm)(b) Lorentz force and velocity of molten zinc in the zinc bath due to the electromagn-etic induction
Fig.11  Flow directions of zinc liquid and the location of the LFV device (αII~α are the angles between the flow direction of zinc liquid and the measurement direction at II~V)
Fig.12  Spectrum analysis of the velocity data of zinc flow in the bath
Fig.13  Turbulence energy spectrum analysis of the velocity data of zinc flow in the bath
[1] Zhang L Y, Li J, Zuo L. Current process and technology investigation situation in the field of steel strip continuous hot-dip galvanization [J]. Steel Rolling, 2005, 22(2): 38
(张理扬, 李 俊, 左 良. 带钢连续热镀锌工艺技术的现状 [J]. 轧钢, 2005, 22(2): 38)
[2] Liu F, Zhao Z W. Temperature analysis of the molten zinc in zinc pot of continuous hot dip galvanized process [J]. J. Inner Mongolia Univ. Sci. Technol., 2011, 30: 18
(刘 芳, 赵增武. 连续热镀锌工艺中锌锅内锌液温度分析 [J]. 内蒙古科技大学学报, 2011, 30: 18)
[3] Gao X C, Fan H B, Guan L K. The control effective aluminum's theory and relatively technical developing in the continuous galvanizing process [J]. Bengang Technol., 2006, (4): 22
(高兴昌, 范洪彬, 关立凯. 控制带钢连续热镀锌工艺中有效铝的研究及当前技术进展 [J]. 本钢技术, 2006, (4): 22)
[4] Li T T, Li T F, Tang Q, et al. Effect of strip-entry temperature on coating during continuous hot-dip galvanizing process [J]. Heat Treat. Met., 2014, 39(9): 48
(李婷婷, 李腾飞, 汤 茜等. 带钢入锌锅温度对连续热镀锌层的影响 [J]. 金属热处理, 2014, 39(9): 48)
[5] Mao F F, Dong A P, Han L Y, et al. Effects of zinc bath outside circulating purification on fluid and heat transfer of continuous hot dip galvanizing pot [J]. Hot Work. Technol., 2017, 46(8): 38
(冒飞飞, 董安平, 韩兰英等. 锌液体外循环净化对连续热镀锌锅流动与传热的影响 [J]. 热加工工艺, 2017, 46(8): 38)
[6] Yang M, Mi L J, Shan Y G, et al. Numerical simulation of mixed convection for low Prandtl number fluid in galvanizing bath [J]. J. Eng. Thermophys., 2008, 29: 115
(杨 茉, 米丽娟, 单彦广等. 锌锅中低Pr流体混合对流的数值模拟 [J]. 工程热物理学报, 2008, 29: 115)
[7] Yang M, Kang H B, Mi L J. Oscillation of mixed convection in galvanizing bath for low Prandtl number fluid [J]. J. Eng. Thermophys., 2008, 29: 2708
(杨 茉, 康宏博, 米丽娟. 锌锅中低Pr流体混合对流的自维持振荡 [J]. 工程热物理学报, 2008, 29: 2708)
[8] Zhu L. Numerical study of thermal and flow fields in a galvanizing zinc pot [D]. Shanghai: East China University of Science and Technology, 2015
(朱 路. 热镀锌锌锅中的流动与传热数值研究 [D]. 上海: 华东理工大学, 2015)
[9] Ajersch F, Ilinca F, Hétu J F. Simulation of flow in a continuous galvanizing bath: Part I. Thermal effects of ingot addition [J]. Metall. Mater. Trans., 2004, 35B: 161
[10] Lee S J, Kim S, Koh M S, et al. Flow field analysis inside a molten Zn pot of the continuous hot-dip galvanizing process [J]. ISIJ Int., 2002, 42: 407
[11] Che C S, Lu J T, Kong G, et al. Role of silicon in steels on galvanized coatings [J]. Acta Metall. Sin. (Engl. Lett.), 2009, 22: 138
[12] Thess A, Votyakov E V, Kolesnikov Y. Lorentz force velocimetry [J]. Phys. Rev. Lett., 2006, 96: 164501
[13] Thess A, Votyakov E, Knaepen B, et al. Theory of the Lorentz force flowmeter [J]. New J. Phys., 2007, 9: 299
[14] Wegfrass A, Diethold C, Werner M, et al. A universal noncontact flowmeter for liquids [J]. Appl. Phys. Lett., 2012, 100: 194103
[15] Wang X D, Kolesnikov Y, Thess A. Numerical calibration of a Lorentz force flowmeter [J]. Meas. Sci. Technol., 2012, 23: 045005
[16] Minchenya V, Karcher C, Kolesnikov Y, et al. Calibration of the Lorentz force flowmeter [J]. Flow Meas. Instrum., 2011, 22: 242
[17] Hernández D, Boeck T, Karcher C, et al. Numerical calibration of a multicomponent local Lorentz force flowmeter [J]. Magnetohydrodynamics, 2017, 53: 233
[18] Viré A, Knaepen B, Thess A. Lorentz force velocimetry based on time-of-flight measurements [J]. Phys. Fluids, 2010, 22: 125101
[19] Jian D D, Karcher C, Xu X J, et al. Development of a non-contact electromagnetic surface velocity sensor for molten metal flow [J]. J. Iron Steel Res. Int., 2012, 19: 509
[20] Jian D D. Flow measurement in liquid metals using Lorentz force velocimetry—Laboratory experiments and numerical simulations [D]. Ilmenau: Ilmenau University of Technology, 2013
[21] Dubovikova N, Kolesnikov Y, Karcher C. Experimental study of an electromagnetic flow meter for liquid metals based on torque measurement during pumping process [J]. Meas. Sci. Technol., 2015, 26: 115304
[22] Kolesnikov Y, Karcher C, Thess A. Lorentz force flowmeter for liquid aluminum: Laboratory experiments and plant tests [J]. Metall. Mater. Trans., 2011, 42B: 441
[23] Hernández D, Boeck T, Karcher C, et al. Numerical and experimental study of the effect of the induced electric potential in Lorentz force velocimetry [J]. Meas. Sci. Technol., 2018, 29: 015301
[24] Stelian C. Calibration of a Lorentz force flowmeter by using numerical modeling [J]. Flow Meas. Instrum., 2013, 33: 36
[25] Wang X D, Thess A, Moreau R, et al. Lorentz force particle analyzer [J]. J. Appl. Phys., 2016, 120: 014903
[26] Miranda R, Barron M A, Barreto J, et al. Experimental and numerical analysis of the free surface in a water model of a slab continuous casting mold [J]. ISIJ Int., 2005, 45: 1626
[27] Deng X X, Xiong X, Wang X H, et al. Effect of nozzle bottom shapes on level fluctuation and meniscus velocity in high-speed continuous casting molds [J]. J. Univ. Sci. Technol. Beijing, 2014, 36: 515
(邓小璇, 熊 宵, 王新华等. 水口底部形状对高拉速板坯连铸结晶器液面特征的影响 [J]. 北京科技大学学报, 2014, 36: 515)
[28] Felten F, Fautrelle Y, Du Terrail Y, et al. Numerical modelling of electromagnetically-driven turbulent flows using LES methods [J]. Appl. Math. Modell., 2004, 28: 15
[29] Wang X D, Fautrelle Y, Etay J, et al. A periodically reversed flow driven by a modulated traveling magnetic field: Part I. Experiments with GaInSn [J]. Metall. Mater. Trans., 2008, 40B: 82
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