非对称中间包稳态浇铸与换包操作的冶金效果
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摘要
为合理评价并优化工业用三流非对称中间包的冶金效果,在对该中间包4种控流方案下稳态浇铸过程流场、温度场数值分析的基础上,通过RTD曲线定量分析了中间包不同控流方式下的钢水混合特性,并应用VOF模型追踪了换包操作时的钢液面行为。结合实际工况特点,从稳态和非稳态两方面研究了增设控流装置前后中间包的冶金性能,实现了对其实际浇铸条件下冶金效果的全面评价。结果表明,无控流装置的原型中间包结构不尽合理,存在明显的短路流,死区比例较大,钢水温度分布不均匀,且各流一致性差,易导致铸坯质量差异。导流隔墙组合湍流抑制器的控流方案可大大改善稳态浇铸时中间包流场及温度分布状况,包内死区比例较原型降低13.28%,3个出口温差仅为0.5K,各流一致性显著提高。然而,此方案在换包操作时可能出现钢液面速度较大及液面波动现象,易导致钢液暴露、二次氧化乃至发生卷渣,应注意换包时间及其液面高度和入口流量的控制。
To rationally assess and optimize the metallurgical effect of an industrially used three-strand asymmetric tundish,the mixing characteristics of molten steel with different tundish configurations were investigated by residence time distribution(RTD)curves based on the analysis of fluid flow and temperature distribution at four flow control schemes,and the behavior of the tundish level was tracked by employing volume-of-fluid(VOF)model.The fluid dynamics behavior of the tundish was studied in term of both steady and unsteady service situations with and without fluid flow control devices,which made it possible to assess comprehensively the metallurgical effect of the given tundish.The results show that the flow control effect of bare tundish is weak.It is observed that there are distinct short-circuit flow and large proportion of dead zone,together with the non-uniform temperature distribution and the flow state discrepancy among the three strands,which will accordingly lead to the quality difference of the bloom castings.The improvements on the fluid flow characteristics and the temperature distribution have been observed in tundish with the combined application of baffles and turbulence inhibitor.The proportion of dead zone is decreased by 13.28%,the temperature difference is only 0.5 Kamong three outlets,along with an improved fluid flow consistency.Additionally,studies also show that this arrangement may have large steel level velocity and level fluctuation during ladle change period.That is likely to bring about exposure,reoxidation and even slag entrainment of molten steel.Attentions should be paid to the control of the ladle change interval,inlet flowrate and the moment height of liquid level.
To rationally assess and optimize the metallurgical effect of an industrially used three-strand asymmetric tundish,the mixing characteristics of molten steel with different tundish configurations were investigated by residence time distribution(RTD)curves based on the analysis of fluid flow and temperature distribution at four flow control schemes,and the behavior of the tundish level was tracked by employing volume-of-fluid(VOF)model.The fluid dynamics behavior of the tundish was studied in term of both steady and unsteady service situations with and without fluid flow control devices,which made it possible to assess comprehensively the metallurgical effect of the given tundish.The results show that the flow control effect of bare tundish is weak.It is observed that there are distinct short-circuit flow and large proportion of dead zone,together with the non-uniform temperature distribution and the flow state discrepancy among the three strands,which will accordingly lead to the quality difference of the bloom castings.The improvements on the fluid flow characteristics and the temperature distribution have been observed in tundish with the combined application of baffles and turbulence inhibitor.The proportion of dead zone is decreased by 13.28%,the temperature difference is only 0.5 Kamong three outlets,along with an improved fluid flow consistency.Additionally,studies also show that this arrangement may have large steel level velocity and level fluctuation during ladle change period.That is likely to bring about exposure,reoxidation and even slag entrainment of molten steel.Attentions should be paid to the control of the ladle change interval,inlet flowrate and the moment height of liquid level.
引文
[1]王建军,包燕平,曲英.中间包冶金学[M].北京:冶金工业出版社,2001.(Wang J J,Bao Y P,Qu Y.Tundish Metallurgy[M].Beijing:Metallurgy Industry Press.2001.)
[2] Sahai Y,Emi T.Tundish Technology for Clean Steel Production[M].Singapore:World Scientific,2008.
[3] Tang H Y,Guo L Z,Wu G H,et al.Hydrodynamic modeling and mathematical simulation on flow field and inclusion removal in a seven-strand continuous casting tundish with channel type induction heating[J].Metals,2018,8(6):374.
[4] Morales R D,Palafox-Ramos J,Barreto J J,et al.Melt flow control in a multistrand tundish using a turbulence inhibitor[J].Metallurgical and Materials Transactions,2000,31B(6):1505.
[5]唐海燕,于满,李京社,等.连铸中间包内部结构优化的数理模拟及冶金效果[J].工程科学学报,2009(s1):38.(Tang H Y,Yu M,Li J S,et al.Numerical and physical simulation on inner structure optimization of a continuous casting tundish and its metallurgical effect[J].Chinese Journal of Engineering,2009(s1):38.)
[6] Merder T,Warzecha M.Optimization of a six-strand continuous casting tundish:Industrial measurements and numerical investigation of the tundish modifications[J].Metallurgical and Materials Transactions,2012,43B(4):856.
[7] Fan C M,Hwang W S.Mathematical modeling of fluid flow phenomena during tundish filling and subsequent initial casting operation in steel continuous casting process[J].ISIJ international,2000,40(11):1105.
[8] Takahashi K,Ando M,Ishii T.Numerical investigation of unsteady molten steel flow and inclusion behavior in the tundish in the ladle change period[J].ISIJ international,2014,54(2):304.
[9] Morales R D,Garcia-Hernandez S,De Jesus Barreto J,et al.Multiphase flow modeling of slag entrainment during ladle change-over operation[J].Metallurgical and Materials Transactions,2016,47B(4):2595.
[10]孙彦辉,蔡开科,赵长亮.非稳态浇注操作对连铸坯洁净度影响[J].钢铁,2008,43(1):22.(Sun Y H,Cai K K,Zhao C L.Effect of transient casting operation on cleanliness of continuously cast strands[J].Iron and Steel,2008,43(1):22.)
[11] Mazumdar D,Yamanoglu G,Shankarnarayanan R,et al.Similarity considerations in the physical modelling of steel making tundish systems[J].Steel Research,1995,66(1):14.
[12] Chen H S,Pehlke R D.Mathematical modeling of tundish operation and flow control to reduce transition slabs[J].Metallurgical and Materials Transactions,1996,27B(5):745.
[13]朱苗勇.连铸中间包内钢液流动与传热耦合过程的计算机模拟[J].金属学报,1997,33(9):933.(Zhu M Y.Numerical simulation of the coupled molten steel flow and heat transfer in continuous casting tundishes[J].Acta Metallurgica Sinica,1997,33(9):933.)
[14] Oro J M F,Morros C S,Somoano J R,et al.Multiphase modelling of the steel grade transition in a continuous casting tundish[C]//ASME 2009 Fluids Engineering Division Summer Meeting.New York:American Society of Mechanical Engineers,2009:2183.
[15] Launder B E,Spalding D B.The numerical computation of turbulent flows[J].Computer Methods in Applied Mechanics and Engineering,1974,3(2):269.
[16] Lai K Y M,Salcudean M,Tanaka S,et al.Mathematical modeling of flows in large tundish systems in steelmaking[J].Metallurgical and Materials Transactions,1986,17B(3):449.
[17] Chakraborty S,Sahai Y.Mathematical modeling of melt flow and heat transfer in continuous casting tundishes[C]//IISC.Tokyo:The Sixth International Iron and Steel Congress,1990,3:189.
[18]祝明妹,文光华,唐萍,等.多流中间包内流体流动模式的分析方法[J].过程工程学报,2008(s1):41.(Zhu M M,Wen G H,Tang P,et al.Analytical method for flow pattern in multi-strand tundish[J].The Chinese Journal of Process Engineering,2008(s1):41.)
[19] Sahai Y,Emi T.Melt flow characterization in continuous casting tundishes[J].ISIJ International,1996,36(6):667.
[20] Sahai Y,Ahuja R.Fluid-flow and mixing of melt in steelmaking tundishes[J].Ironmaking and Steelmaking,1986,13(5):241.
[21]张立峰,王勇,周德光,等.连铸中间包钢水流动及夹杂物运动的数值模拟[J].钢铁,2004,39(s1):515.(Zhang L F,Wang Y,Zhou D G,et al.Numerical simulation on fluid flow and inclusion motion in continuous casting tundish[J].Iron and Steel,2004,39(s1):515.)
[22] Zhang L.Transient fluid flow phenomena in continuous casting tundishes[J].Iron and Steel Technology,2010,7(7):55.
[2] Sahai Y,Emi T.Tundish Technology for Clean Steel Production[M].Singapore:World Scientific,2008.
[3] Tang H Y,Guo L Z,Wu G H,et al.Hydrodynamic modeling and mathematical simulation on flow field and inclusion removal in a seven-strand continuous casting tundish with channel type induction heating[J].Metals,2018,8(6):374.
[4] Morales R D,Palafox-Ramos J,Barreto J J,et al.Melt flow control in a multistrand tundish using a turbulence inhibitor[J].Metallurgical and Materials Transactions,2000,31B(6):1505.
[5]唐海燕,于满,李京社,等.连铸中间包内部结构优化的数理模拟及冶金效果[J].工程科学学报,2009(s1):38.(Tang H Y,Yu M,Li J S,et al.Numerical and physical simulation on inner structure optimization of a continuous casting tundish and its metallurgical effect[J].Chinese Journal of Engineering,2009(s1):38.)
[6] Merder T,Warzecha M.Optimization of a six-strand continuous casting tundish:Industrial measurements and numerical investigation of the tundish modifications[J].Metallurgical and Materials Transactions,2012,43B(4):856.
[7] Fan C M,Hwang W S.Mathematical modeling of fluid flow phenomena during tundish filling and subsequent initial casting operation in steel continuous casting process[J].ISIJ international,2000,40(11):1105.
[8] Takahashi K,Ando M,Ishii T.Numerical investigation of unsteady molten steel flow and inclusion behavior in the tundish in the ladle change period[J].ISIJ international,2014,54(2):304.
[9] Morales R D,Garcia-Hernandez S,De Jesus Barreto J,et al.Multiphase flow modeling of slag entrainment during ladle change-over operation[J].Metallurgical and Materials Transactions,2016,47B(4):2595.
[10]孙彦辉,蔡开科,赵长亮.非稳态浇注操作对连铸坯洁净度影响[J].钢铁,2008,43(1):22.(Sun Y H,Cai K K,Zhao C L.Effect of transient casting operation on cleanliness of continuously cast strands[J].Iron and Steel,2008,43(1):22.)
[11] Mazumdar D,Yamanoglu G,Shankarnarayanan R,et al.Similarity considerations in the physical modelling of steel making tundish systems[J].Steel Research,1995,66(1):14.
[12] Chen H S,Pehlke R D.Mathematical modeling of tundish operation and flow control to reduce transition slabs[J].Metallurgical and Materials Transactions,1996,27B(5):745.
[13]朱苗勇.连铸中间包内钢液流动与传热耦合过程的计算机模拟[J].金属学报,1997,33(9):933.(Zhu M Y.Numerical simulation of the coupled molten steel flow and heat transfer in continuous casting tundishes[J].Acta Metallurgica Sinica,1997,33(9):933.)
[14] Oro J M F,Morros C S,Somoano J R,et al.Multiphase modelling of the steel grade transition in a continuous casting tundish[C]//ASME 2009 Fluids Engineering Division Summer Meeting.New York:American Society of Mechanical Engineers,2009:2183.
[15] Launder B E,Spalding D B.The numerical computation of turbulent flows[J].Computer Methods in Applied Mechanics and Engineering,1974,3(2):269.
[16] Lai K Y M,Salcudean M,Tanaka S,et al.Mathematical modeling of flows in large tundish systems in steelmaking[J].Metallurgical and Materials Transactions,1986,17B(3):449.
[17] Chakraborty S,Sahai Y.Mathematical modeling of melt flow and heat transfer in continuous casting tundishes[C]//IISC.Tokyo:The Sixth International Iron and Steel Congress,1990,3:189.
[18]祝明妹,文光华,唐萍,等.多流中间包内流体流动模式的分析方法[J].过程工程学报,2008(s1):41.(Zhu M M,Wen G H,Tang P,et al.Analytical method for flow pattern in multi-strand tundish[J].The Chinese Journal of Process Engineering,2008(s1):41.)
[19] Sahai Y,Emi T.Melt flow characterization in continuous casting tundishes[J].ISIJ International,1996,36(6):667.
[20] Sahai Y,Ahuja R.Fluid-flow and mixing of melt in steelmaking tundishes[J].Ironmaking and Steelmaking,1986,13(5):241.
[21]张立峰,王勇,周德光,等.连铸中间包钢水流动及夹杂物运动的数值模拟[J].钢铁,2004,39(s1):515.(Zhang L F,Wang Y,Zhou D G,et al.Numerical simulation on fluid flow and inclusion motion in continuous casting tundish[J].Iron and Steel,2004,39(s1):515.)
[22] Zhang L.Transient fluid flow phenomena in continuous casting tundishes[J].Iron and Steel Technology,2010,7(7):55.