Fluid Mixing in Ladle of RH Degasser Induced by Down Flow

Yoshitomi, Kota; Nagase, Misato; Uddin, Md. Azhar; Kato, Yoshiei

doi:10.2355/isijinternational.isijint-2015-714

Cited by 13 publications

(9 citation statements)

References 15 publications

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“…However, according to the principle of geometric similarity and dynamic similarity, water model experiment can reasonably predict the steady flow characteristics of molten steel. [11,13,41] Hence, from the qualitative and quantitative perspectives, the predicted steady fluid flow pattern and flow velocity are compared with the air-water model experimental results to validate the gas-liquid flow mathematical model. The air-water model experiments are conducted based on the 1/5 scale models of 90 and 210 t RH furnaces, respectively.…”

Section: Water Model Experimentsmentioning

confidence: 99%

“…[9][10][11] Due to the vacuum condition and the high temperature, it is difficult to observe the gas-liquid flow phenomena directly. [12][13][14][15] Computational fluid dynamics (CFD) has become an increasingly popular method to investigate multiphase flow and transfer behaviors in RH. [5,[15][16][17] Up to now, algebraic slip model (ASM), a remarkable mathematical model proposed by Manninen and Taivassalo, [18] has been widely used to predict the multiphase flow features, [19][20][21] especially gas holdup distribution, fluid velocity, and flow patterns in gas-liquid flow.…”

Section: Introductionmentioning

confidence: 99%

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Interaction between CO–Ar–Molten Steel Flow and Decarburization Reaction in Rheinstahl–Heraeus

Chen

Lei

Wang

2021

steel research int.

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Computational fluid dynamics (CFD) is an effective tool to investigate the transfer phenomena in Rheinstahl-Heraeus (RH), which is a multifunctional vacuum refining reactor with various chemical reactions. However, the reported mathematical models, which are based on the assumption of steady Ar-molten steel flow, ignore the CO gas generated by the chemical reaction between carbon and oxygen in RH. Herein, Based on the algebraic slip model, a two-way coupling model (T-WCM) is developed to explore the unsteady fluid flow (CO-Ar-molten steel) and mass transfer phenomena during decarburization chemical reaction. The measured data from the water model experiment and the industrial experiment are used to validate the numerical results. The carbon mass concentration predicted by T-WCM is closer to the result from industrial experiment than that predicted by one-way coupling model (O-WCM). The mole number of CO gas is about 3 times that of argon gas injected into RH, and the stirring effect of CO gas leads to a more complicated multiphase flow, enhances the mass transfer and prompts the reaction rate. Therefore, the gas-liquid flow and decarburization process in RH can be described more precisely only when CO gas is considered by T-WCM.

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Section: Water Model Experimentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Interaction between CO–Ar–Molten Steel Flow and Decarburization Reaction in Rheinstahl–Heraeus

Chen

Lei

Wang

2021

steel research int.

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“…In 1990s, Nippon Steel Corporation of Japan developed the Revolutionary Degassing Activator (REDA), a vacuum refining reactor similar to SSRH (Kitamura et al, 2000). The gas-liquid behavior is a dominant factor of circulation flow (Park et al, 2000;Dai et al, 2020), solute mixing (Ajmani et al, 2004;Zhang and Li, 2014;Yoshitomi et al, 2016) and chemical reactions (Takahashi et al, 1995;Chen and He, 2019). However, it is very difficult to observe fluid flow directly because of the high temperature and vacuum conditions.…”

Section: Introductionmentioning

confidence: 99%

Turbulent flow with nonequilibrium chemical reaction in single snorkel RH

Chen

Lei

Wang

et al. 2021

HFF

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Purpose The reported mathematical models of gas–liquid flow in single snorkel Rheinstahl–Heraeus (SSRH) are based on the assumption of steady Ar-molten steel flow. The purpose of this paper is to develop a mathematical model to describe the unsteady turbulent flow (CO-Ar-molten steel) with nonequilibrium decarburization reaction. Design/methodology/approach On the base of the finite volume method, the computational fluid dynamics software CFX is used to predict the unsteady fluid flow, the spatial distributions of CO/argon gas and carbon element. The water model experiment and the industrial experiment are carried out to verify the mathematical models. Findings A two-way coupling model (T-WCM) based on algebraic slip model is developed to investigate the coupling phenomena. The related results show that T-WCM is more rigorous and accurate than one-way coupling model in predicting carbon content of molten steel. The amount of CO gas, which can enhance turbulent flow and mass transfer, is about three times the argon gas blown into SSRH. Originality/value CO gas is the key factor in investigating the transport phenomena. This study fully reveals the truth about the unsteady gas-liquid flow in SSRH. It is necessary to adopt T-WCM based on algebraic slip model to describe the CO-Ar-molten steel flow phenomenon.

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confidence: 99%

“…The tracer was added from the feed inlet port on the vacuum chamber sidewall, and the mixing time was defined as the first time when the conductivity stabilized at AE5%, [21,36] AE3%, [37] or AE1%. [38] As the mixing time is related to the location of monitors and the fluid flow field distribution in the ladle, [6] many researchers have given out the mixing time of several points for different positions and various operation conditions. [23,39,40] However, it is difficult to figure out the mixing time distribution on the whole vertical center section in the ladle.…”

mentioning

confidence: 99%

Water Modeling on Circulating Flow and Mixing Time in a Ruhrstahl–Heraeus Vacuum Degasser

Liu

Zhang

et al. 2021

steel research int.

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Due to the difficulties and less flexibility of industrial trials, physical modeling and mathematical modeling have been widely used to study the fluid flow phenomena during metallurgical processes, [1][2][3][4] including the multiphase fluid flow, [5][6][7] mass transfer, [8,9] chemical reaction, [10,11] bubbles and inclusions behavior, [12][13][14] and other complex phenomena in the ladle. The Ruhrstahl-Heraeus (RH) is a vital refining process to produce high-quality steel. Circulation rate [15][16][17] and mixing time, [18,19] as two significant parameters, are usually used to evaluate the refining efficiency of RH degasser, such as the melting and mixing of addition alloy. [20] In recent years, investigations on the circulating flow and the mixing phenomena during RH degassing process have been conducted to improve its refining efficiency and service life. [5,21,22] However, several investigations focused on the whole velocity distribution in the RH system using physical models. [21,23] A lot of measurement methods and empirical formulas were reported to predict the circulation rate, including the direct measurement using an intelligent velocity instrument, [24] the overflow method, [25] and the peak value method. [26][27][28] The injection gas flow rate and injection nozzles, [5] the immersion depth of snorkels, [9,[29][30][31] and the pressure in the vacuum chamber [26,32] have great influences on the circulation flow rate. Furthermore, some researchers devoted to the study on the nozzle blockage [27] refractory wear erosion, [33] or the bottom blowing [34,35] to optimize the RH refining process. The stimulus-response experiment was the usual method used to measure mixing time. The tracer was added from the feed inlet port on the vacuum chamber sidewall, and the mixing time was defined as the first time when the conductivity stabilized at AE5%, [21,36] AE3%, [37] or AE1%. [38] As the mixing time is related to the location of monitors and the fluid flow field distribution in the ladle, [6] many researchers have given out the mixing time of several points for different positions and various operation conditions. [23,39,40] However, it is difficult to figure out the mixing time distribution on the whole vertical center section in the ladle. Based on the previously reported work, some equations for calculating the mixing time are shown in Table 1. Many previous investigations indicated that the mixing time has exponential relation with the stirring power, and the range of the index of their relational expression is À0.5 to À0.3. [36,[41][42][43]

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Fluid Mixing in Ladle of RH Degasser Induced by Down Flow

Cited by 13 publications

References 15 publications

Interaction between CO–Ar–Molten Steel Flow and Decarburization Reaction in Rheinstahl–Heraeus

Interaction between CO–Ar–Molten Steel Flow and Decarburization Reaction in Rheinstahl–Heraeus

Turbulent flow with nonequilibrium chemical reaction in single snorkel RH

Water Modeling on Circulating Flow and Mixing Time in a Ruhrstahl–Heraeus Vacuum Degasser

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