Modelling of air ingress and pressure distribution in ladle shroud system for continuous casting of steel

Wang, Laihua; Lee, Hae-Geon; Hayes, Peter C.

doi:10.1002/srin.199501125

Cited by 15 publications

(16 citation statements)

References 4 publications

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“…The gas phase also had a tendency to flow down along the wall of the shroud nozzle, and the bubble size was larger than 1ϫ10 Ϫ3 m in diameter. The above observations are in good accord with the results reported by Wang et al 3,6) It was also observed that the opening of the slide gate had a large influence on the mixing and bubble formation. As seen in Fig.…”

Section: Bubble Formation and Dispersionsupporting

confidence: 92%

“…(3) Once the water flows from the buffer tank (2) via the slide gate (5) and the shroud nozzle (2ϫ10 Ϫ2 m IDϫ 1.0 m L) (7) to the tundish (11) has reached a steady state, the gas is introduced into the shroud nozzle through a gas inlet port (1.5ϫ10 Ϫ3 m in diameter) by opening a gas inlet valve (6). The gas flow rate is regulated to maintain a predetermined flow rate using a regulator attached to the gas flow meter (9).…”

Section: Methodsmentioning

confidence: 99%

“…This is considered to be due to the dependence of the pressure drop inside the shroud pipe (underneath the slide gate) on the degree of constriction. 6) As the opening of the slide gate increases, the degree of the constriction decreases and hence the pressure drop, which causes turbulence, becomes smaller. Wang et al 6) measured the change in the air ingress with the opening of the slide gate, and reported that the suction power decreased by increasing the opening.…”

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confidence: 99%

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Cold Model Study on Inclusion Removal from Liquid Steel Using Fine Gas Bubbles.

Cho

Lee

2001

ISIJ International

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A water model study was undertaken to investigate inclusion removal from liquid steel using fine gas bubbles, which were created by injecting air into a shroud nozzle just underneath the slide gate. The water flow rate was varied in the range of 2.0-3.2 m 3 hr Ϫ1, which is equivalent to 1.77-2.83 m s Ϫ1 of the linear velocity at the exit of the shroud nozzle. The ratio of gas to liquid flow rates was varied in the range of 0-12 % by volume. Polyethylene, PVC and ABS particles were used to imitate the inclusion. The characteristics of the bubble formation varied with the gas inlet position along the shroud: the closer the slide gate, the better the mixing between the gas and liquid phases. This was dependent on the slide gate opening: the smaller the opening, the more turbulence and hence the better mixing of the gas and the liquid. The relative removal efficiency was fairly independent of such variables as liquid flow rate, i.e., linear velocity, the slide gate opening (up to 58 % by area), and inclusion concentration. However, this was greatly affected by the wettability, i.e., contact angle of the inclusion with the liquid: the larger the contact angle, the higher the efficiency. It is concluded that the governing factor which determines the removal efficiency of the inclusion from liquid steel is the wettability of the inclusion with the steel, and the idea proposed in the present study should be an effective means for production of clean steels.

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Section: Bubble Formation and Dispersionsupporting

confidence: 92%

Section: Methodsmentioning

confidence: 99%

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confidence: 99%

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Cold Model Study on Inclusion Removal from Liquid Steel Using Fine Gas Bubbles.

Cho

Lee

2001

ISIJ International

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“…22,30,32,[43][44][45][46][47][48][49][50][51] As early as 1973, Szekely et al 22) modeled the difference between fluid flow in the mold from a straight nozzle and that from a bifurcated nozzle. An extensive investigation of bifurcated nozzle flow was performed by Najjar et al, 44) who explored the effects of nozzle shape, angle, height, width, ports thickness, bottom geometry, inlet velocity profile, and inlet shape.…”

Section: Fluid Flow In the Nozzlementioning

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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“…increased to maintain the desired flow rate. Once the slide Mathematical modeling of the pressure profile along the gate reaches its maximum position, production must stop nozzle has been reported for both liquid only [15] and liquidand the nozzle must be replaced. Thus, it is important to find gas systems.…”

Section: Introductionmentioning

confidence: 99%

Effects of clogging, argon injection, and continuous casting conditions on flow and air aspiration in submerged entry nozzles

Bai

Thomas

2001

Metall Mater Trans B

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The inter-related effects of nozzle clogging, argon injection, tundish bath depth, slide-gate opening position, and nozzle-bore diameter on the steel flow rate and pressure in continuous-casting slidegate nozzles are quantified using computational models of three-dimensional (3-D) multiphase turbulent flow. The results are validated with measurements on operating steel continuous slab-casting machines and are presented for practical conditions with the aid of an inverse model. Predictions show that initial clogging may enhance the steel flow rate due to a potential streamlining effect before it becomes great enough to restrict the flow channel. The clogging condition can be detected by comparing the measured steel flow rate to the expected flow rate for those conditions, based on the predictions of the inverse model presented here. Increasing argon injection may help to reduce air aspiration by increasing the minimum pressure, which is found just below the slide gate. More argon is needed to avoid a partial-vacuum effect at intermediate casting speeds and in deeper tundishes. Argon flow should be reduced during shallow tundish and low casting speed conditions (such as those encountered during a ladle transition) in order to avoid detrimental effects on flow pattern. Argon should also be reduced at high casting speed, when the slide gate is open wider and the potential for air aspiration is less. The optimal argon flow rate depends on the casting speed, tundish level, and nozzle-bore diameter and is quantified in this work for a typical nozzle and range of bore diameters and operating conditions.

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Modelling of air ingress and pressure distribution in ladle shroud system for continuous casting of steel

Cited by 15 publications

References 4 publications

Cold Model Study on Inclusion Removal from Liquid Steel Using Fine Gas Bubbles.

Cold Model Study on Inclusion Removal from Liquid Steel Using Fine Gas Bubbles.

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

Effects of clogging, argon injection, and continuous casting conditions on flow and air aspiration in submerged entry nozzles

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