Model Experiments on the Mixing Time in a Bottom Blown Bath Covered with Top Slag

Yamashita, Shintaro; Miyamoto, K.; Iguchi, Manabu; Zeze, Masafumi

doi:10.2355/isijinternational.43.1858

Cited by 15 publications

(14 citation statements)

References 3 publications

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“…At 2 lit/min of gas flow, the average gas velocity U g is equal to 0.54 m/s, whereas the corresponding terminal rise velocity estimated from Eq. [10] is 0.20 m/s. With these new estimates, the fractional energy dissipation caused by slippage is found to 0.37, which is practically identical to 0.40, as reported in Table IV.…”

Section: B Quantification Of Dissipation Coefficientsmentioning

confidence: 98%

“…Equations [10] and [11], as one would note here, are valid for spherical cap bubbles rising through a water bath. Similarly, within the ascending gas-liquid plume, the rise velocity of the bubble/gas can be taken to be the sum of the liquid velocity (synonymous with average plume velocity) and the slip velocity of the characteristic bubble.…”

Section: Gas-liquid Interactions Within the Ascending Plumementioning

confidence: 99%

“…Despite the difficulty in representing molten steel and slag system exactly using room temperature analogs, several studies [3][4][5][6][7][8][9][10][11][12][13] have been reported over the years, in which, the role of a slag has been investigated via an oilwater or similar room temperature system. These studies, in general, have indicated that flows and mixing in gasstirred vessels become ''sluggish'' in the presence of an overlying second-phase liquid.…”

Section: Dipak Mazumdar and Roderick Il Guthriementioning

confidence: 99%

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Modeling Energy Dissipation in Slag-Covered Steel Baths in Steelmaking Ladles

Mazumdar

Guthrie

2010

Metall Mater Trans B

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Physical and mathematical modeling of energy dissipation phenomena in a gas-stirred ladle with, and without, an overlying second-phase liquid have been carried out at relatively low gas flow rate and specific energy input rate. Data from the literature are applied to infer the extent of energy dissipation caused by various mechanisms. An analysis reveals that bubble slippage and friction at the vessel walls dominate energy dissipation in such systems, each contributing roughly one third of the input energy. The remainder is dissipated because of turbulence in the bulk of the liquid, the formation of a spout, and interactions between the upper phase and the bulk liquid when an overlying liquid is present. Remarkably, the overlying liquid despite its small volume (~3 pct to 13 pct of the bulk), is found to dissipate about 10 pct of input energy. To understand the way the total input energy is dissipated via the overlying liquid, flow and mixing studies were carried out with different types of upper phase liquids. Tracer dispersion studies conducted with Petroleum ether as the overlying liquid show reasonably intense flow within the upper phase with no noticeable entrainment around the spout. In contrast, a thick layer of highly viscous upper phase liquid such as mustard oil shows extensive deformation of the upper phase around the spout, but no discernable motion within. However, remarkably, the thickness of the upper phase rather than its physical properties was found to influence bath hydrodynamics and mixing most significantly. A mechanism based on the rerouting of the surfacing plume and the attendant reversal of flow in the vicinity of the spout is advocated to explain energy dissipation caused by the overlying liquid. This finding is rationalized with our experimental results on composition adjustment with sealed argon bubbling (CAS) alloy addition procedures reported more than two decades ago, wherein flow reversal caused by the baffle in the immediate vicinity of the surfacing plume was shown to cause significant energy dissipation, leading to much sluggish flow and slower mixing in the bulk of the liquid, in comparison with an equivalent unbaffled situation.

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Section: B Quantification Of Dissipation Coefficientsmentioning

confidence: 98%

Section: Gas-liquid Interactions Within the Ascending Plumementioning

confidence: 99%

Section: Dipak Mazumdar and Roderick Il Guthriementioning

confidence: 99%

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Modeling Energy Dissipation in Slag-Covered Steel Baths in Steelmaking Ladles

Mazumdar

Guthrie

2010

Metall Mater Trans B

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“…Ogawa and Onou measured the mixing time and slag‐metal masstransfer coefficient in gas bubbling and induction stirring by water model and plant scale experiments. Oils were used as top layers to simulate the slag phase in water models . Yamashita et al carried out water model experiments to clarify the effect of the top oil layer on the mixing time in a bottom blown bath.…”

Section: Introductionmentioning

confidence: 99%

“…Argon-stirred ladles are commonly used in the secondary refining [1] to homogenize chemical compositions and the temperature [2][3][4][5] , to remove inclusions, [6,7] and to enhance the slag-metal reactions. [8][9][10] Many publications have been done to investigate the mixing phenomena in argonstirred ladles experimentally [11][12][13][14][15][16][17][18][19][20][21][22] and numerically, [23][24][25][26][27][28][29][30][31][32][33][34] but less of them coupled the melting of alloy particles.…”

Section: Introductionmentioning

confidence: 99%

Effect of Melt Superheat and Alloy Size on the Mixing Phenomena in Argon‐Stirred Steel Ladles

Duan¹,

Zhang²,

Thomas

2018

steel research int.

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In the current study, the melting and mixing behavior of the alloy in argon‐stirred steel ladles is simulated based on the turbulent fluid flow. The formation of the solidified steel shells around cold ferroalloy particles is considered and the discrete phase model is adopted to predict the motion of ferroalloy particles. Ferroalloy particles are heated by the surrounding liquid during their travel trajectories and the mixing of dissolved alloy solute is described by the species transport model as the steel shell disappears. User defined functions are used to record the melting time and the trajectory length of each ferroalloy particle, as well as to check the mixing criteria in every cell and predict the local mixing time in the entire computational domain. Mixing time maps which visualize the mixing efficiency are obtained as a novel representation to describe the local mixing time in the entire ladle. The effects of the superheat of the melt and the diameter of alloy particles are investigated. The results show that the higher superheat of the melt and the smaller size of alloy particle facilitate the melting and mixing of the alloy in argon‐stirred steel ladles.

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Numerical and Experimental Investigations of Steel Mixing Time in a 130-t Ladle

Warzecha

Jowsa

Warzecha

et al. 2008

steel research international

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This paper presents the experimental determination of variations in the chemical composition of a steel bath after introducing an alloy addition, and a numerical simulation corresponding to the conditions in an industrial ladle furnace. The numerical model and experimental studies aimed to determine the mixing time necessary for achieving the assumed degree of chemical homogenisation under the conditions of operation of the ladle furnace. In addition, through the numerical studies, the metal bath mixing time for a variable position of the porous plug is investigated.

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Model Experiments on the Mixing Time in a Bottom Blown Bath Covered with Top Slag

Cited by 15 publications

References 3 publications

Modeling Energy Dissipation in Slag-Covered Steel Baths in Steelmaking Ladles

Modeling Energy Dissipation in Slag-Covered Steel Baths in Steelmaking Ladles

Effect of Melt Superheat and Alloy Size on the Mixing Phenomena in Argon‐Stirred Steel Ladles

Numerical and Experimental Investigations of Steel Mixing Time in a 130-t Ladle

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