臺灣博碩士論文加值系統

連鑄(Continuous Casting)也就是連續鑄鋼的簡稱，這項程序在鋼胚生產的過程中，是最終鋼胚品質好壞的重要關鍵，然而在連鑄過程中為促使凝殼順利脫離銅模，會添加澆鑄粉，澆鑄粉為人造合成渣，經由數種原物料如:一氧化碳、二氧化硫、氧化鋁等混合而成，當澆鑄粉與鋼液表面接觸後會形成液態渣層，而此渣層常會隨著銅模內流場的帶動，被捲到鋼液之中，這樣的現象我們稱為捲渣，不管多寡只要有渣被帶入鋼液中對最後鋼胚品質就有莫大的影響，因此探討捲渣為何發生，及如何減少捲渣情況的發生，對連鑄過程進行優化，是目前世界許多鋼廠極力探討的議題，以利往後產品品質能夠更進一步提升。

本次研究利用CFD流體力學分析軟體 ANSYS Fluent，針對目前鋼廠實際運用之連續鑄鋼(Continuous Casting)程序分析其鑄鋼模內流場與捲渣的發生。透過以下參數如: 澆鑄速度 、噴嘴插入深度、氬氣氣泡大小及噴嘴堵塞對流場的影響，比較在不同參數下鑄鋼模內流場的變化及捲渣(Slag Entrainment)發生的程度，模擬在何種參數設定，之流場其表面波動最穩定，最能減緩捲渣的產生，並將最後優化的結果，提供業界做為參考依據，進而能夠使最後產出的鋼胚缺陷大幅降低，使產品品質更加提升。

Continuous Casting is one of the important keys to the quality of the final steel in the process of steel production. However, in the continuous casting process in order to separation the crust from the copper mold smoothly, the casting powder will be added. Casting powder is composition with several kind materials such as CO、CO2 and Al2O3, etc. When casting powder contact with liquid steel, it will become liquid slag layer. After this liquid slag layer break by the fluid flow, the layer will separate as many particles. Those particles will driven into the molten steel along with the flow field in the copper mold usually. This phenomenon is called slag entrainment. No matter how many slag particles entrained into the steel, it always produce a huge defect on the final production. Now a lot of steel making companies are focus on this issue about how to optimization the process of Continuous Casting.
In this study, the Ansys fluent CFD software is used to study the original model of Continuous Casting Machine. Analyze how to decrease the slag entrainment happened. In this study we change four parameters on Continuous Casting process like Casting speed、Insert depth of Submerged entry nozzle、Argon bubble size and nozzle clogging region. To change these four parameters, we can found in which combination may decrease the slag entrainment happened effectively.

摘要 i
Abstract ii
目錄 iii
表目錄 vi
圖目錄 vii
第一章 緒論 1
1.1 前言 1
1.2 連續鑄鋼機運作流程及種類 2
1.2.1 立式連鑄機 3
1.2.2 立彎式連鑄機 5
1.2.3弧形連鑄機 6
1.2.4水平連鑄機 7
1.3連續鑄鋼機之捲渣問題 8
1.4 文獻回顧 10
1.5研究動機 21
1.6論文架構 22
第二章 數值模擬方法與工具 23
2.1 統御方程式 24
2.2 紊流模型 25
2.2.1 k-ε 紊流模型 27
2.2.2大渦流模擬(Large-Eddy Simulation, LES) 31
2.2.2.1 次網格模型(Sub-grid scale modeling, SGS modeling) 33
2.3 Volume of Fraction(VOF)多相流模型 34
2.4 SIMPLEC數值計算理論 35
2.5最佳運算模型與驗證 36
第三章 研究方法 43
3.1幾何模型介紹 43
3.2幾何模型建立 43
3.2.1模型繪製 43
3.2.2 網格建立 46
3.3 模擬參數設定 48
3.3.1 材料參數設定 48
3.3.2 邊界條件設定 49
第四章 模擬結果與討論 50
4.1 澆鑄速度之影響(1.2 m/min、1.6 m/min、2.0 m/min) 50
4.2 浸入式噴嘴(Submerged Entry Nozzle, SEN)插入深度對模內流場之影響 53
4.3 通入氬氣(Argon)之影響 56
4.4噴口之堵塞現象 60
第五章 結論與未來展望 67
5.1 結論 67
參考文獻 68

[1]B. Thomas, "Continuous Casting (metallurgy)."
[2]PRIMETALS TECHNOLOGIES VERTICAL CASTING,
https://www.primetals.com/portfolio/continuous-casting/vertical-casting/
[3]The Library of Manufacturing, Casting, http://www.thelibraryofmanufacturing.com/
[4]SteelConstruction.info, https://www.steelconstruction.info/Steel_manufacture."
[5]Technical University of Košice, http://web.tuke.sk/hf-kmzaz/webplynuleodlievanie/pages/03typyZPO.html."
[6]T. Wertli, "Horizontal continuous casting technology in the eighties," Metallurgia, vol. 53, p. 192, 1986.
[7]B. G. Thomas, "Modeling of the continuous casting of steel—past, present, and future," Metallurgical and materials transactions B, vol. 33, no. 6, pp. 795-812, 2002.
[8]W. C. Chiang, I. S. Tseng, C. T. Cheng, and J. K. Wu, "The Formation and Contol of Macroinclusion in Steelmaking Processes," no. 2007 CIMME Annual Convention, 2007.
[9]D. Harris and J. Young, "Water Modeling--a Viable Production Tool," Iron and Steel Society, Inc., The Shrouding of Steel Flow for Casting and Teeming, pp. 73-86, 1982.
[10]P. Zhao, Q. Li, S. B. Kuang, and Z. Zou, "Mathematical Modeling of Liquid Slag Layer Fluctuation and Slag Droplets Entrainment in a Continuous Casting Mold Based on VOF-LES Method," High Temperature Materials and Processes, vol. 36, no. 5, 2017.
[11]H. Nakato, K. Saito, Y. Oguchi, N. Namura, and K. Sorimachi, "Surface quality improvement of continuously cast blooms by optimizing solidification in early stage," Iron and Steel Society, Inc., Continuous Casting., pp. 193-197, 1987.
[12]T. NOZAKI and S. ITOYAMA, "Horizontal Continuous Casting Processes," Transactions of the Iron and Steel Institute of Japan, vol. 27, no. 5, pp. 321-331, 1987.
[13]A. MATSUSHITA, K. ISOGAMI, M. TEMMA, T. NINOMIYA, and K. TSUTSUMI, "Direct observation of molten steel meniscus in CC mold during casting," Transactions of the Iron and Steel Institute of Japan, vol. 28, no. 7, pp. 531-534, 1988.
[14]B. Thomas and H. Zhu, "Thermal distortion of solidifying shell near meniscus," Urbana, vol. 51, p. 61801, 1996.
[15]Y. H. Wang, "A study of the effect of casting conditions on fluid flow in the mold using water modelling," in Steelmaking Conference Proceedings., 1990, vol. 73, pp. 473-480.
[16]J. Kubota, N. Kubo, T. Ishii, M. Suzuki, N. Aramaki, and R. Nishimachi, "Steel flow control in continuous slab caster mold by traveling magnetic field," NKK Technical Review(Japan), vol. 85, pp. 1-9, 2001.
[17]J. Kubota, K. Okimoto, A. Shirayama, and H. Mukarami, "Meniscus flow control in the mold by traveling magnetic field for high speed slab caster," in 1991 Steelmaking Conference, 1991, vol. 1991.
[18]X. Huang, B. G. Thomas, and F. Najjar, "Modeling superheat removal during continuous casting of steel slabs," Metallurgical and Materials Transactions B, vol. 23, no. 3, pp. 339-356, 1992.
[19]R. McDavid and B. Thomas, "Flow and thermal behavior of the top surface flux/powder layers in continuous casting molds," Metallurgical and materials transactions B, vol. 27, no. 4, pp. 672-685, 1996.
[20]B. G. Thomas, A. Denissov, and H. Bai, "Behavior of argon bubbles during continuous casting of steel," in Steelmaking Conference Proceedings, 1997, vol. 80, pp. 375-384: IRON AND STEEL SOCIETY OF AIME.
[21]B. Thomas, L. Mika, and F. Najjar, "Simulation of fluid flow inside a continuous slab-casting machine," Metallurgical Transactions B, vol. 21, no. 2, pp. 387-400, 1990.
[22]B. G. Thomas, X. Huang, and R. Sussman, "Simulation of argon gas flow effects in a continuous slab caster," Metallurgical and Materials Transactions B, vol. 25, no. 4, pp. 527-547, 1994.
[23]X. Huang and B. Thomas, "Modeling of transient flow phenomena in continuous casting of steel," Canadian Metallurgical Quarterly, vol. 37, no. 3-4, pp. 197-212, 1998.
[24]B. G. Thomas and L. Zhang, "Mathematical modeling of fluid flow in continuous casting," ISIJ international, vol. 41, no. 10, pp. 1181-1193, 2001.
[25]Y. Miki and S. Takeuchi, "Internal defects of continuous casting slabs caused by asymmetric unbalanced steel flow in mold," ISIJ international, vol. 43, no. 10, pp. 1548-1555, 2003.
[26]L. Zhang, Y. Wang, and X. Zuo, "Flow Transport and Inclusion Motion in Steel Continuous-Casting Mold under Submerged Entry Nozzle Clogging Condition," Metallurgical and Materials Transactions B, vol. 39, no. 4, pp. 534-550, 2008.
[27]L. C. Hibbeler and B. G. Thomas, "Mold slag entrainment mechanisms in continuous casting molds," Iron and Steel Technology, vol. 10, no. 10, pp. 121-136, 2013.
[28]N. Bessho, R. Yoda, H. Yamasaki, T. Fujii, T. Nozaki, and S. Takatori, "Numerical analysis of fluid flow in continuous casting mold by bubble dispersion model," ISIJ international, vol. 31, no. 1, pp. 40-45, 1991.
[29]L. Zhang, J. Aoki, and B. G. Thomas, "Inclusion removal by bubble flotation in a continuous casting mold," Metallurgical and materials transactions b, vol. 37, no. 3, pp. 361-379, 2006.
[30]S. Sarkar, V. Singh, S. K. Ajmani, R. K. Singh, and E. Z. Chacko, "Effect of Argon Injection in Meniscus Flow and Turbulence Intensity Distribution in Continuous Slab Casting Mold Under the Influence of Double Ruler Magnetic Field," ISIJ International, vol. 58, no. 1, pp. 68-77, 2018.
[31]"World Steel in Figures 2017," World Steel Association, 2017.
[32]S. V. Patankar and D. B. Spalding, "A calculation procedure for heat, mass and momentum transfer in three-dimensional parabolic flows," International Journal of Heat and Mass Transfer, vol. 15, no. 10, pp. 1787-1806, 1972.
[33]" Millennium Prize Problems—Navier–Stokes Equation," claymath.org, Clay Mathematics Institute, 2017.
[34]G. G. Stokes, "On the Effect of the Internal Friction of Fluids on the Motion of Pendulums," On the Effect of the Internal Friction of Fluids on the Motion of Pendulums, vol. 9, 1851.
[35]O. Reynolds, "An experimental investigation of the circumstances which determine whether the motion of water shall be direct or sinuous, and of the law of resistance in parallel channels," Philosophical Transactions of the Royal Society, vol. 174, pp. 935-982, 1883.
[36]N. Rott, "Note on the history of the Reynolds number," Annual Review of Fluid Mechanics, vol. 22, pp. 1-11, 1990.
[37]A. Sommerfeld, "Ein Beitrag zur hydrodynamischen Erkläerung der turbulenten Flüssigkeitsbewegüngen (A Contribution to Hydrodynamic Explanation of Turbulent Fluid Motions)," International Congress of Mathematicians, vol. 3, pp. 116-124, 1908.
[38]A. N. Kolmogorov, "The local structure of turbulence in incompressible viscous fluid for very large Reynolds numbers," in Dokl. Akad. Nauk SSSR, 1941, vol. 30, no. 4, pp. 299-303.
[39]B. E. Launder and D. B. Spalding, "The numerical computation of turbulent flows," in Numerical Prediction of Flow, Heat Transfer, Turbulence and Combustion: Elsevier, 1983, pp. 96-116.
[40]V. Yakhot, S. Orszag, S. Thangam, T. Gatski, and C. Speziale, "Development of turbulence models for shear flows by a double expansion technique," Physics of Fluids A: Fluid Dynamics, vol. 4, no. 7, pp. 1510-1520, 1992.
[41]Q. Chen, "Comparison of different k-ε models for indoor air flow computations," Numerical Heat Transfer, Part B Fundamentals, vol. 28, no. 3, pp. 353-369, 1995.
[42]V. Yakhot and S. A. Orszag, "Renormalization group analysis of turbulence. I. Basic theory," Journal of scientific computing, vol. 1, no. 1, pp. 3-51, 1986.
[43]L. P. Kadanoff, "Scaling laws for Ising models near T (c)," Physics, vol. 2, pp. 263-272, 1966.
[44]J. Smagorinsky, "General circulation experiments with the primitive equations: I. The basic experiment," Monthly weather review, vol. 91, no. 3, pp. 99-164, 1963.
[45]D. K. Lilly, "A proposed modification of the Germano subgrid‐scale closure method," Physics of Fluids A: Fluid Dynamics, vol. 4, no. 3, pp. 633-635, 1992.
[46]J. W. Deardorff, "A numerical study of three-dimensional turbulent channel flow at large Reynolds numbers," Journal of Fluid Mechanics, vol. 41, no. 2, pp. 453-480, 1970.
[47]D. C. Wilcox, Turbulence modeling for CFD. DCW industries La Canada, CA, 1993.
[48]K. Timmel, S. Eckert, G. Gerbeth, F. Stefani, and T. Wondrak, "Experimental modeling of the continuous casting process of steel using low melting point metal alloys—the LIMMCAST program," ISIJ international, vol. 50, no. 8, pp. 1134-1141, 2010.
[49]R. Chaudhary, C. Ji, B. G. Thomas, and S. P. Vanka, "Transient Turbulent Flow in a Liquid-Metal Model of Continuous Casting, Including Comparison of Six Different Methods," Metallurgical and Materials Transactions B, vol. 42, no. 5, pp. 987-1007, 2011.
[50]D. Mazumdar and J. Evans, "A model for estimating exposed plume eye area in steel refining ladles covered with thin slag," Metallurgical and Materials Transactions B, vol. 35, no. 2, pp. 400-404, 2004.
[51]M. Javurek, P. Gittler, R. Rössler, B. Kaufmann, and H. Preßlinger, "Simulation of nonmetallic inclusions in a continuous casting strand," Steel research international, vol. 76, no. 1, pp. 64-70, 2005.
[52]B. G. Thomas, "Modeling of continuous casting defects related to mold fluid flow," Iron and Steel Technology, vol. 3, no. 7, p. 127, 2006.
[53]SINOM GROUP CO., LTD,http://www.sinomgroup.com/
[54]T. Teshima, M. Osame, K. Okimoto, and Y. Nimura, "Improvement of surface property of steel at high casting speed," Iron and Steel Society, Inc., Continuous Casting., pp. 115-122, 1988.
[55]Z.-q. Liu, B.-k. Li, M.-f. Jiang, and F. Tsukihashi, "Modeling of Transient Two-Phase Flow in a Continuous Casting Mold Using Euler-Euler Large Eddy Simulation Scheme," ISIJ International, vol. 53, no. 3, pp. 484-492, 2013.