Evaluation of the Effects of Gas Injection in the Vaccum Chamber of a RH Degasser on Melt Circulation and Decarburization Rates

Neves, Leonardo; Oliveira, H.P.; Tavares, Roberto Parreiras

doi:10.2355/isijinternational.49.1141

Cited by 24 publications

(18 citation statements)

References 9 publications

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“…[11,12] Since the bubble buoyancy is the driving force, blowing gas from the ladle bottom or vacuum chamber bottom is an effective method to increase the circulation flow rate. [13,14] Recently, the single snorkel vacuum degasser (also named as SSF in China or REDA in Japan) has been investigated to improve the vacuum refining efficiency. In the single snorkel vacuum degasser, the side blowing in up snorkel is replaced by the ladle bottom blowing.…”

Section: Introductionmentioning

confidence: 99%

Simulation on Flow Field and Mixing Phenomenon in Single Snorkel Vacuum Degasser

Geng¹,

Zhang²,

Liu³

et al. 2014

steel research int.

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Numerical simulation method has been used to investigate the flow field and mixing phenomenon in single snorkel degasser with ladle bottom blowing. The numerical results showed that the flow field inside the single snorkel vacuum degasser can be optimized in order to achieve higher recirculation rates and smaller mixing times, which are important to refining. This can be done by locating the gas injection point away from the center of the ladle. Under the conditions analyzed in present work, the optimum location of the gas injection point could be located 0.3 m from the center of the ladle. The circulation flow rate twice as high as that of a similar size RH degasser can be achieved on the condition of the optimized position. However, the ladle bottom blowing gas flow rate should be kept to a maximum of 400 NL/min in order to avoid slag entrapment in present work.

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Section: Introductionmentioning

confidence: 99%

Simulation on Flow Field and Mixing Phenomenon in Single Snorkel Vacuum Degasser

Geng¹,

Zhang²,

Liu³

et al. 2014

steel research int.

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“…[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.…”

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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“…With the emerge of vacuum technology, it is possible to produce ULC steels with carbon content of less than 0.005 %mass which is called interstitial free (IF) steels [3][4][5][6]. It is well known that the interstitial elements such as carbon (C) and nitrogen (N) in the steel are lower owing to vacuum treatment, thereafter one of the most important properties of ULC steel (formability) is improved to apply for automotive body.…”

Section: Introductionmentioning

confidence: 99%

Strength and Microstructure of Cold-Rolled if Steel

Bui¹,

Le²

2016

Acta Metall Slovaca

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With the emerge of vacuum technology, it is possible to produce ultra low carbon (ULC) steels with carbon content of less than 0.005 %mass which is called interstitial free (IF) steels. In this study, strength and microstructure of IF steel after cold-rolling have been determined. The initial steel plates were cold-rolled using two different cold reductions (CR) as 80 and 90% in total, thereafter the steel sheets were cut into specimens for tensile test and optical microscopy. Ultimate tensile strength (UTS) of the cold-rolled steel was high (650807 MPa), but the elongation (EL) was low (3.55.3%). Meanwhile, UTS of the annealed steels was decreased to 290 MPa when soaking temperature was 800 o C because of stress relief and recrystallization. It was concluded that higher CR (more severe deformation) increased the strength but decreased the ductility of the IF steels. In consistence with micrograph of the steels, X-ray diffraction (XRD) results showed that microstructure of the cold-rolled and annealed IF steels was only ferrite. Textures, one of the most important factors affecting the recrystallization, were found in cold-rolled steels. Keywords:Cold reduction, Cold-rolling, IF steel, Residual stress, Texture IntroductionThe demands for the steel with excellence formability from automotive industry have accelerated the progress in the steelmaking process, leading to the development of the ultra low carbon (ULC) steels containing carbon less than 0.01 %mass [1,2]. With the emerge of vacuum technology, it is possible to produce ULC steels with carbon content of less than 0.005 %mass which is called interstitial free (IF) steels [3][4][5][6]. It is well known that the interstitial elements such as carbon (C) and nitrogen (N) in the steel are lower owing to vacuum treatment, thereafter one of the most important properties of ULC steel (formability) is improved to apply for automotive body. In general, two important objectives being pursued by the automobile industry are a decrease in car weight and improvements in safety [7]. To realize these requirements, several researches have been implemented to reduce thickness of the steel sheet, increase strength and improve press formability of the steel. For example, J. Galan et al. studied on improving strength and dent resistant capacities with bake hardenable ULC steels in order to fulfill the requirements of thinner sheet steel for automotive applications [2]. M. Wang et al. analyzed the source and disadvantages of macro-inclusions in titanium stabilized ULC steel and reported that the total

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Evaluation of the Effects of Gas Injection in the Vaccum Chamber of a RH Degasser on Melt Circulation and Decarburization Rates

Cited by 24 publications

References 9 publications

Simulation on Flow Field and Mixing Phenomenon in Single Snorkel Vacuum Degasser

Simulation on Flow Field and Mixing Phenomenon in Single Snorkel Vacuum Degasser

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

Strength and Microstructure of Cold-Rolled if Steel

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