Mixing Time and Liquid Circulation Rate in Steelmaking Ladles with Vertical Gas Injection.

Turkoglu, Hasmet; Farouk, Bakhtier

doi:10.2355/isijinternational.31.1371

Cited by 61 publications

(50 citation statements)

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“…This model has been used to calculate two-phase fluid flow in a continuous casting mold. 80) 49,[81][82][83] In this model, one velocity field for the liquid steel and another separate velocity field for the gas phase are solved. The momentum equation for each phase is affected by the other phase through inter-phase drag terms.…”

Section: Langrangian Two Phase Modelmentioning

confidence: 99%

Mathematical Modeling of Iron and Steel Making Processes. Mathematical Modeling of Fluid Flow in Continuous Casting.

2001

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Fluid flow is very important to quality in the continuous casting of steel. With the high cost of empirical investigation and the increasing power of computer hardware and software, mathematical modeling is becoming an important tool to understand fluid flow phenomena. This paper reviews recent developments in modeling phenomena related to fluid flow in the continuous casting mold region, and the resulting implications for improving the process. These phenomena include turbulent flow in the nozzle and mold, the transport of bubbles and inclusion particles, multi-phase flow phenomena, the effect of electromagnetic forces, heat transfer, interfacial phenomena and interactions between the steel surface and the slag layers, the transport of solute elements and segregation. The work summarized in this paper can help to provide direction for further modeling investigation of the continuous casting mold, and to improve understanding of this important process.KEY WORDS: mathematical modeling; computational simulation; review; continuous casting; nozzles; molds; multiphase; turbulent; fluid flow; electromagnetic; coupled solidification; inclusion entrapment; segregation.steel. This paper will review recent developments in modeling each of the phenomena above, which are related to fluid flow in the continuous casting mold, and the resulting implications for improving the continuous casting process. Fluid Flow ModelingA typical three dimensional fluid flow model solves the continuity equation and Navier Stokes equations for incompressible Newtonian fluids, which are based on conserving mass (one equation) and momentum (three equations) at every point in a computational domain. 17,18) The solution of these equations, given elsewhere in this issue, 19) yields the pressure and velocity components at every point in the domain. At the high flow rates involved in this process, these models must incorporate turbulent fluid flow. Many different turbulence models have been employed by different researchers for fluid flow in continuous casting, such as effective viscosity models 20,21) (for the cylindrical mold and straight nozzle), one equation turbulence models (turbulent energy plus a given length-scale), 22) two-equation turbulence models such as the K-e Model, 19,23) LES (Large Eddy Simulation), [24][25][26][27][28] possibly with a SGS (sub-grid scale) model, 29,30) and DNS (Direction Numerical Simulation). 19)Among these models, direct numerical simulation is the simplest yet most computationally-demanding method. DNS uses a fine enough grid (mesh), to capture all of the turbulent eddies and their motion with time. To achieve more computationally-efficient results, turbulence is usually modeled on a courser grid using a time-averaged approximation, such as the popular K-e model, 23) which averages out the effect of turbulence using an increased effective viscosity field, m eff . This approach requires solving two additional partial differential equations for the transport of turbulent kinetic energy and its dissipation rate.19...

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Section: Langrangian Two Phase Modelmentioning

confidence: 99%

Mathematical Modeling of Iron and Steel Making Processes. Mathematical Modeling of Fluid Flow in Continuous Casting.

2001

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“…1,6) For the function of argon gas in ladle refining, many studies were performed in the earlier years through water model 1,2,4,6) and mathematical simulation 5,[7][8][9] from different aspects such as (a) gas injection and transport, [10][11][12][13] (b) the effect of top slag layer, [14][15][16][17][18][19] (c) stirring and mixing. [20][21][22][23][24][25][26][27][28] In 1975, Nakanishi et al 10) investigated the correlation between gas mixing efficiency and mass transfer in a model ladle and explained this correlation with turbulence theory. Later, Mori and Sano 11) summarized an equation to describe the relationship between the bubble size and gas flowrates for a single plug ladle.…”

Section: Introductionmentioning

confidence: 99%

Effect of Gas Blown Modes on Mixing Phenomena in a Bottom Stirring Ladle with Dual Plugs

Tang

Guo

et al. 2016

ISIJ International

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Gas stirring plays a significant role in steelmaking process. The stirring effect is often assessed by the mixing time. In the past, the effects of many factors such as the number and position and relative angle of porous plugs in a ladle, as well as gas flowrate on the mixing time have been studied and some beneficial results used in industrial practice. However, for a ladle with dual plugs, the researches on gas flowrate basically focused on the blowing mode with the same gas flowrates for every plug (Mode-S), while the mode with different flowrates (Mode-D) has not yet been reported. In the present work, a water model for a 120 t ladle is carried out to mainly compare the effect of the two gas blowing modes on mixing. Two porous plugs are located at 0.55-0.70R (R is the radius of ladle bottom), with different relative angles (45-180°) and total flowrates (6.92-18.45 NL/min). The results show that Mode-D can significantly change the mixing time. Compared with Mode-S, the mixing time is respectively decreased by 50 seconds at 6.92 NL/min and 30 seconds at 18.45 NL/min when the plug positions are located at 0.64R. The results of mathematical simulation explain the phenomena. In the Mode-D, the strong gas plume forms a larger circulation flow to stir the ladle and the weak plume forms a smaller one. Under this case, the interference and collision from two plumes are weakened and the dissipation of stirring energy is decreased, thus the mixing time is shortened.

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“…Although data collected by this method are not easily affected by other impurities, a pH meter malfunctions easily, and stable measured values cannot be obtained easily. Therefore, another measurement using a conductivity meter has been presented 8,9) and is applied in this study to investigates the relationship between bottom blowing conditions and molten iron phase mixing.…”

Section: Introductionmentioning

confidence: 99%

Effect of Gas Bottom Blowing Conditions on Mixing of Molten Iron inside an Ironmaking Smelter

Chou

Liu³

et al. 2010

Mater. Trans.

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To aid efficient use of the gas flow rate for a smelting reduction furnace, this study investigates the effect of gas bottom blowing and stirring on the mixing time of the molten iron phase. In this study, transparent acrylic is used to construct a water model, which is 60% as big as the original experimental melting reduction furnace of the China Steel Corporation. The mixing time of the molten iron phase in the water model is measured by using gas bottom blowing and changing the number of tuyeres (from three to five), the tuyere placement, the tuyere size (6.0-15.0 mm), and the gas flow rate per tuyere (80-120 NL/min).The mixing trials adopt KCl as an indicator and use water filtrated using reverse osmosis (RO) in place of liquid iron to investigate the effect of gas bottom blowing conditions on mixing of the molten iron phase. The experimental results indicate that in the cases of four tuyeres in the square-corner and triangle-corner-center placements, 10.0 mm tuyeres yield the shortest mixing time (and thus the best mixing effect) under different total gas flow rates. In the case of five tuyeres in the square-corner-center placement, 10.0 mm tuyeres also have the shortest mixing time under total gas flow rates of 400 NL/min and 500 NL/min. However, 12.5 mm tuyeres have the shortest mixing time under a total gas flow rate of 600 NL/min. In addition, in the case of three tuyeres in the triangle-corner placement, 12.5 mm tuyeres have the shortest mixing time under different total gas flow rates. When the gas flow rate per tuyere is 80 NL/min, the fewer the tuyeres, the shorter the mixing time. Depending on tuyere placement, some of the energy injected by the gas may be counteracted. For example, when a bottom-blowing tuyere exists in the center, the gas injection from that tuyere may be counteracted by that of adjacent tuyeres such that energy dissipates. In contrast, a tuyere placement without a center tuyere may yield better mixing effects. In this study, the best combination for mixing in the liquid phase is four 10.0 mm tuyeres in the square-corner placement and a total gas flow rate of 480 NL/min.

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Mixing Time and Liquid Circulation Rate in Steelmaking Ladles with Vertical Gas Injection.

Cited by 61 publications

References 1 publication

Mathematical Modeling of Iron and Steel Making Processes. Mathematical Modeling of Fluid Flow in Continuous Casting.

Mathematical Modeling of Iron and Steel Making Processes. Mathematical Modeling of Fluid Flow in Continuous Casting.

Effect of Gas Blown Modes on Mixing Phenomena in a Bottom Stirring Ladle with Dual Plugs

Effect of Gas Bottom Blowing Conditions on Mixing of Molten Iron inside an Ironmaking Smelter

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