Physical-numerical simulation and application of optimization of flow control device in a single-stand slab tundish
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摘要: 合理的控流装置结构和布局是提升中间包内钢液洁净度的关键。采用数值模拟与水力学模拟相结合的方法对某厂单流板坯中间包控流装置不同组合方式及位置的钢液流动行为、RTD曲线及夹杂物去除率进行分析，结果表明，在坝墙间距不变情况下，挡墙往长水口侧移动适当距离会延长钢液平均停留时间9.9 ～17.9 s、死区体积比例减小0.45～0.85个百分点、中间包低温区域减少，净化钢液的能力有所提升；在坝墙间距改变的情况下，坝墙间距过大可能会导致中间包浇注区钢液的紊乱，钢液平均停留时间延长不明显，死区体积比例反而增大0.33个百分点，中间包低温区域增大，夹杂物总去除率上升0.18个百分点。因此，坝墙间距为473.5 mm及挡墙与长水口距离为720 mm是较为理想的控流装置组合方式。采用优化方案后，中间包内钢液洁净度得到有效提升。Abstract: The reasonable structure and layout of flow control devices are crucial for improving the cleanliness of molten steel within the tundish in the continuous casting process. A combined approach using numerical simulation and physical modeling was employed to analyze the steel flow behavior, residence time distribution (RTD) curves, and inclusions removal rates for different combinations and positions of flow control devices in a single-strand slab tundish at a certain plant. The results indicate that when the distance between the dam and baffle remains constant, a suitable shift of the baffle wall towards the ladle shroud side can prolong the average residence time of the liquid steel by 9.9 s to 17.9 s, reduce the dead zone volume fraction by 0.45 to 0.85 percentage, and decrease the low-temperature region in the tundish, thereby enhancing the purification capability of the molten steel. However, when the distance between the dam and baffle is changed, an excessively large distance between them may cause turbulence in the casting zone of the tundish, with the average residence time of the steel showing no significant extension. Instead, the dead zone volume fraction increases by 0.33 percentage, leading to an enlargement of the low-temperature region in the tundish and a 0.18 percentage increase in the overall inclusion removal rate. Thus, a dam-to-dam distance of 473.5 mm and a baffle-to-ladle shroud distance of 720 mm are considered to be the more ideal combination for flow control device settings. The steel cleanness in the single-strand tundish has been effectively enhance by applying the optimized flow control scheme.
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Key words:
- tundish /
- flow control device /
- physical and numerical modeling /
- RTD curves /
- inclusion removal
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图 2 方案A2不同时刻中间包内水模试验和数值模拟计算的流动状态对比
Figure 2. Comparison of flow pattern between experiment and simulation under Scheme A2
（a）28 s；（b）95 s；（c）141 s；（d）360 s
图 3 原型中间包和方案B2水模试验和数值模拟RTD曲线对比
(A) 原型中间包；(B) 方案B2
Figure 3. Comparison of RTD curves between experiment and simulation under scheme B2 and prototype tundish
图 4 各方案中间包长水口中心纵截面流线
（a）原型；（b）A1；（c）A2；（d）A3；（e）B1；（f）B2
Figure 4. Streamline field in the center longitudinal section of ladle shroud in tundish under different schemes
图 5 各方案中间包冲击区自由液面速度云图
（a）原型；（b）A1；（c）A2；（d）A3；（e）B1；（f）B2
Figure 5. Free surface velocity nephogram of tundish impact zone under different schemes
图 6 各控流方案中间包RTD曲线
（a）方案原型～A3；（b）方案原型～B2
Figure 6. RTD curves of tundish under different schemes
图 7 各方案中间包长水口中心纵截面温度云图
（a）原型；（b）A1；（c）A2；（d）A3；（e）B1；（f）B2
Figure 7. Temperature contours in center longitudinal section of ladle shroud in tundish under different schemes
图 8 各方案中间包内夹杂物去除率
Figure 8. Inclusion removal rate in the tundish under different schemes
表 1 中间包数值模拟计算所用主要工艺参数
Table 1. Main industrial parameters of tundish applied in the numerical simulations
原中间包
工作吨
位/t原中间包
工作液
位/mm长水口
浸入
深度/mm铸坯断面
尺寸/
(mm×mm)典型拉坯
速度/
(m$ \cdot $min−1)长水口
内径/mm浸入式水口
内径/mm夹杂物
密度/
(kg$ \cdot $m−3)钢液物理
密度/
(kg·m−3)钢的摩尔
质量/
(g·mol−1)钢液黏度/
(Pa·s)22 994 400 1248 ×2001.1 75 62 3500 7000 55.86 0.0062 
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表 2 单流板坯中间包数值模拟计算方案
Table 2. Calculation scheme of single-strand tundish applied in the numerical simulations
方案 编号 参数 挡墙距
长水口/mm坝墙中心
间距/mm挡坝距浸入
式水口/mm原型中间包 920 473.5 679 坝墙间距不变 A1 770 473.5 679 A2 720 473.5 679 A3 670 473.5 679 坝墙间距改变 B1 720 673.5 679 B2 920 673.5 479
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表 3 中间包模型和原型参数比例
Table 3. Tundish model and prototype parameter ratio
线性比 速度比 流量比 平均停留时间比 公式 $ { \lambda } $ $ {{v}}_{\text{m}}\text{=}\sqrt{{ \lambda }}\text{∙}{{v}}_{\text{p}} $ $ {{Q}}_{\text{m}}\text{=}{{ \lambda }}^{\tfrac{\text{5}}{\text{2}}}\text{∙}{{Q}}_{\text{p}} $ $ {\overline{{t}}}_{\text{m}}\text{=}\dfrac{{{L}}_{\text{m}}{/}{{V}}_{\text{m}}}{{{L}}_{\text{p}}{/}{{V}}_{\text{p}}} $ 值 1/2 0.707 0.17678 0.707 注：$ \lambda $为线性比；下标p、m分别代表原型和模型；v、L分别为流速、特征长度。
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表 4 原型中间包和方案B2水模试验和数值模拟平均停留时间误差对比
Table 4. Comparison of average residence time between experiment and simulation under scheme B2 and prototype tundish
方案 水模试验值/s 数值模拟/s 相对误差/% 原型 649.5 686.6 5.40 B2 649.5 686.8 5.43
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表 5 各控流方案中间包RTD曲线分析结果
Table 5. Analysis of RTD curves in the tundish under different schemes
方案 $ {t}_{\mathrm{r}} $/s $ {t}_{\mathrm{p}} $/s $ \bar{t}/\mathrm{s} $ Vp/% Vd/% Vm/% 原型 171.0 421.0 686.6 43.11 7.68 49.21 A1 177.5 406.5 696.5 41.92 7.23 50.85 A2 179.0 414.5 704.5 42.12 6.83 51.05 A3 197.0 376.5 696.5 41.16 7.46 51.38 B1 167.0 391 687.5 40.58 7.57 51.85 B2 156.5 405.5 686.8 40.92 8.01 51.07
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表 6 中间包优化前后夹杂物评级对比
Table 6. Comparison of inclusions ranking before and after tundish optimization
夹杂物评级/级 优化前占比/% 优化后占比/% B类 D类 B类 D类 0.5～1.0 26.44 97.95 32.42 100 1.5～2.5 70.33 2.05 66.59 0 >2.5 3.23 0 0.99 0
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