# Flow Behavior of Liquid Steel in Fewer Strands Casting of Six-Strand Bloom Tundish

^{1}

^{2}

^{*}

## Abstract

**:**

## 1. Introduction

## 2. Model Description

#### 2.1. Geometric Models and Meshing

#### 2.2. Assumptions

- (1)
- The influence of surface fluctuation and surface slag on flow of tundish is not considered.
- (2)
- The liquid steel flow is steady incompressible flow, and the fluid is driven by the initial velocity of the pure liquid phase.
- (3)
- Assume that the flow process in the tundish is steady state.
- (4)
- The temperature change in the whole process is not considered.
- (5)
- The motion of liquid steel belongs to turbulent flow with high Reynolds number.
- (6)
- The inclusion is assumed to be spherical in shape.
- (7)
- Regardless of the collision polymerization between the inclusion particles and the adsorption of the wall surface, it is determined that the inclusion in the z direction is absorbed by the slag layer when it reaches the liquid level.
- (8)
- The object of study is spherical nonmetallic inclusions in liquid steel.
- (9)
- The main way to remove inclusions in tundish is adsorption of liquid level slag.

#### 2.3. Fundamental Equations

#### 2.3.1. Fluid Flow

^{3}; t is flow time, s; $\overrightarrow{v}$ velocity vector, m/s; ${S}_{m}$ is source phase.

#### 2.3.2. Motion of Inclusions

^{2}; $\rho p$ is the density of the inclusion particles, kg/m

^{3}; ${F}_{other}$ is other interphase forces.

#### 2.4. Boundary Conditions

#### 2.5. Calculation of Inclusion Removal

#### 2.6. Average Residence Time of Tundish

#### 2.7. Simulation Scheme

## 3. Results and Discussion

#### 3.1. Analysis of Tundish RTD Curve and Flow Field in Normal Casting

#### 3.2. Analysis of Tundish RTD Curve and Flow Field in Fewer Strands Casting

#### 3.3. Analysis of Inclusion Removal Rate

#### 3.3.1. Inclusion Removal Rate of Total Tundish

#### 3.3.2. Effect of Fewer Strands Casting on Inclusion Removal

#### 3.4. Gas Curtain Position under Optimal Strand Closing Scheme

## 4. Conclusions

- (1)
- Compared with normal casting, the flow field in the tundish deteriorates in the process of fewer strands casting, and the dead zone volume increases somewhat compared with normal casting. The dead zone volume fraction calculated separately by each flow in each scheme increases by about 2~10%.
- (2)
- Under the condition of fewer strands casting, the inclusion removal rate of the tundish with the particle size of 30–70 μm decreased to different degrees, and the inclusion removal effect was the worst when the second strand is closed. The removal rates of inclusions with diameter 30, 50, and 70 μm in the tundish decreased from 39.1%, 74.2%, and 93.3% to 28.0%, 65.8%, and 83.6%, respectively.
- (3)
- When the first strand is closed, the inclusion removal consistency of casting region on both sides of tundish is good; when the second or third strand is closed, the consistency of inclusion removal with particle size of 50~90 μm in the pound region on both sides of tundish is poor.
- (4)
- When the tundish needs to close a strand to adapt to the production rhythm, closing first strand has the least influence on the removal of inclusions in the tundish. The removal rates of inclusions at 10, 30, 50, 70, and 90 μm changed from 12.4%, 39.1%, 74.2%, 93.3%, and 95.6% to 14.7%, 36.4%, 76.4%, 85.3%, and 93.8%, respectively.
- (5)
- Setting an gas curtain in the tundish of the first strand can reduce the dead zone volume. The dead zone volume of the second and third strand is reduced from 14.8% and 16.4% to 13.9% and 14.1%, respectively. The removal of 10 μm and 30 μm inclusions increased from 14.7% and 36.4% to 39.2% and 62.6%.

## Author Contributions

## Funding

## Data Availability Statement

## Acknowledgments

## Conflicts of Interest

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**Figure 1.**Diagram of tundish structure: vertical view (

**a**); front view (

**b**); schematic diagram of fewer strands casting (

**c**).

**Figure 4.**RTD curves of tundish for normal casting and liquid steel flow diagram: RTD curve (

**a**); liquid steel flow diagram (

**b**).

**Figure 5.**RTD curves of tundish for fewer strands casting: scheme 1 (

**a**); scheme 2 (

**b**); scheme 3 (

**c**).

**Figure 6.**Liquid steel flow diagram in tundish for fewer strands casting: scheme 1 (

**a**); scheme 2 (

**b**); scheme 3 (

**c**).

**Figure 7.**Outlet section velocity cloud of liquid steel in tundish for fewer strands casting: scheme 1 (

**a**); scheme 2 (

**b**); scheme 3 (

**c**).

**Figure 10.**Comparison of inclusion removal rate between casting region 1 and 2 in each scheme: scheme 1 (

**a**); scheme 2 (

**b**); scheme 3 (

**c**).

Parameters | Value |
---|---|

Density of liquid steel/(kg·m^{−3}) | 7020 |

Density of inclusion/(kg·m^{−3}) | 2200 |

Viscosity of liquid steel/(kg·m^{−1}·s^{−1}) | 0.0062 |

Inlet velocity/(m·s^{−1}) | 1.1266 |

Gravitational acceleration/(m·s^{−2}) | 9.81 |

Density of argon/(kg·m^{−3}) | 1.6228 |

Viscosity of liquid steel/(kg·m^{−1}·s^{−1}) | 0.0000212 |

Original Scheme | Scheme 1 | Scheme 2 | Scheme 3 |
---|---|---|---|

Normal casting | Only close first strand | Only close second strand | Only close third strand |

Parameter | Position 1 | Position 2 | Position 3 |
---|---|---|---|

Distance from the air curtain to the center of the ladle shroud, mm | Under porous baffle wall | 1200 | 1750 |

argon flow, L/min | 12 L/min | 12 L/min | 12 L/min |

Scheme | Opened Strand | Response Time/s | Peak Concentration Time/s | Average Residence Time/s | Volume Fraction of Dead Zone/% | Volume Fraction of Plug Zone/% | Volume Fraction of Well-Mixed Zone/% |
---|---|---|---|---|---|---|---|

Normal casting | 1 | 66 | 253.5 | 806 | 10.9 | 19.8 | 69.3 |

2 | 16 | 68.5 | 648 | 8.5 | 6.5 | 85.0 | |

3 | 34 | 162.5 | 705 | 8.0 | 13.9 | 78.1 | |

Scheme 1 | 2 | 20.5 | 81.5 | 802 | 14.8 | 6.4 | 78.8 |

3 | 30.5 | 585.0 | 941 | 16.4 | 32.7 | 50.9 | |

Scheme 2 | 1 | 161 | 553.0 | 1 050 | 17.9 | 34.0 | 48.1 |

3 | 40 | 267.5 | 757 | 10.0 | 20.3 | 69.7 | |

Scheme 3 | 1 | 123.5 | 517.5 | 1 062 | 16.4 | 30.2 | 53.4 |

2 | 22 | 318.5 | 767 | 9.8 | 22.2 | 68.0 |

Scheme | Strand Number | Response Time/s | Peak Concentration Time/s | Average Residence Time/s | Volume Fraction of Dead Zone/% | Volume Fraction of Plug Zone/% | Volume Fraction of Well-Mixed Zone/% |
---|---|---|---|---|---|---|---|

Normal casting | 1 | 66 | 253.5 | 806 | 10.9 | 19.8 | 69.3 |

2 | 16 | 68.5 | 648 | 8.5 | 6.5 | 85.0 | |

3 | 34 | 162.5 | 705 | 8.0 | 13.9 | 78.1 | |

Scheme 1 (no argon) | 2 | 20.5 | 81.5 | 802 | 14.8 | 6.4 | 78.8 |

3 | 30.5 | 585.0 | 941 | 16.4 | 32.7 | 50.9 | |

Scheme 1 | 2 | 31.3 | 330.3 | 823.1 | 13.9 | 21.9 | 64.0 |

(Position 2) | 3 | 49.3 | 351.3 | 912.1 | 14.1 | 21.9 | 63.9 |

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**MDPI and ACS Style**

Wang, X.; Wang, S.; Hu, H.; Xie, X.; Wu, C.; Chen, D.; Long, M.
Flow Behavior of Liquid Steel in Fewer Strands Casting of Six-Strand Bloom Tundish. *Metals* **2023**, *13*, 706.
https://doi.org/10.3390/met13040706

**AMA Style**

Wang X, Wang S, Hu H, Xie X, Wu C, Chen D, Long M.
Flow Behavior of Liquid Steel in Fewer Strands Casting of Six-Strand Bloom Tundish. *Metals*. 2023; 13(4):706.
https://doi.org/10.3390/met13040706

**Chicago/Turabian Style**

Wang, Xianyang, Sijie Wang, Hao Hu, Xin Xie, Chenhui Wu, Dengfu Chen, and Mujun Long.
2023. "Flow Behavior of Liquid Steel in Fewer Strands Casting of Six-Strand Bloom Tundish" *Metals* 13, no. 4: 706.
https://doi.org/10.3390/met13040706