Modeling of Slag Eye Area in Argon Stirred Ladles

Abstract

Fig. 1. A schematic of ladle gas injection operation illustrating the formation of slag eye.ture water model in the presence of different upper phase liquids as a function of gas flow rate, bath depth, and thickness of the overlying liquid. The authors also critically reviewed previous studies [1][2][3] and went on to show that available correlations on slag eye area are largely inadequate to describe their experimental results. Based on the principles of momentum conservation, a fresh analysis of the subject was presented and a new correlation, having the following general form, was developed is the dimensionless slag eye area and (r L U P 2 /DrgH) is the densimetric Froude number. For the first time, the influence of density of the upper phase vis a vis the bulk liquid on slag eye area was acknowledged explicitly. The proposition that slag eye area varies with the square root of densimetric Froude number was also supported adequately from the experimental observation of Yonezawa and Schwerdtfeger. For oil-water system, a and b were assigned to Ϫ0.15 and 0.574 5) respectively and on the basis of such, an explicit version of Eq. (4) was advocated. Generalization, nevertheless, was not helpful and large scatter was noted as data from various gas liquid systems were fitted against Eq. (4). This, reproduced from Ref. 5), is shown in Fig. 2. Given such, it is reasonable to assume that we do not yet have a sufficiently reliable frame work to predict slag eye area in gas stirred ladle systems. Despite advancements in our understanding of the subject, 1-5) possible influences of surface tension and kinematic viscosity of the upper phase liquid on eye area are not known with certainty. Clearly, further investigation is needed to address such concerns. Present Work ExperimentalA 1/10th scale water model of a 150 tonne steel ladle was employed to investigate slag eye area (see Fig. 1), its formation and size. In this, physical dimensions and operating parameters in the model ladle were deduced from those of the full scale system on the basis of geometric and dynamic similarity. For ready reference these are summarized in Table 1. During a typical experiment, the model vessel was filled up to the predetermined level, requisite amount of the upper phase liquid was poured in gradually and air/ oxygen injected at the desired rate through a centric nozzle, placed at the bottom of the vessel. Following a brief flow establishment period, video recording of the slag eye area was initiated. The following four steps were generally followed to infer eye area from video recording experiments viz. a. Video recording was typically carried out for duration of about 5 min using an arrangement as shown in Fig. 3. b. Optimum numbers of frames/snapshots (typically about fifteen) at desired time intervals were subsequently captured from the continuous stream using the VLC TM (Video LAN Client) media player and saved in a desktop folder in the JPEG format. c. The area of the eye was estimated from each such captured images using a pre calib...

Modeling of Gas-Steel-Slag Three-Phase Flow in Ladle Metallurgy: Part I. Physical Modeling

“…Then they proposed a new model for the slag eye, 11) which is an extension to the previous one, where the eye size was computed from the primary operating variables of the ladle and demonstrated reliable predictive abilities in a variety of multi-phase systems. Peranandhanthan and Mazumdar 12) developed a new polynomial correlation for slag eye area, in which the dimensionless slag eye area can be expressed in terms of Froude number, density ratio, and Reynolds number. Recently, Krishnapisharody and Irons 13) proposed a new model for slag eyes in the ladles covered with thick slag, indicating that the eyes formed can be smaller than the spout region when the slag layer is sufficiently thick.…”

Formation of Slag ‘eye’ in an Inert Gas Shrouded Tundish

“…The % error was calculated according to the following formula: It is seen from Table 1 that the percentage errors in the estimated slag 'eye' radius range from 75.27% to 99.33% which are huge. The percentage errors in the radius obtained from other researchers 7,9,11,12) which had different operating slag height to bath height ratios were even larger and hence, are not shown here. This clearly proves the fact that the correlations developed to predict the open 'eye' area in laldes can not be used for tundishes.…”

“…On comparing the present water model results with the estimates obtained from the correlations for ladles, 2,3,7,9,11,12,15) it can be concluded that the mechanism of slag 'eye' formation in a tundish is different from that in ladles, and hence, a new correlation needs to be developed for predicting the size of slag 'eye' in a tundish.…”

“…The drawback of their model was that it did not consider the upper buoyant slag phase present on the top of bulk liquid phase and used only DPM to model the interaction of the gas phase with bulk liquid. Various researchers 6,7,12,13,15) have suggested that the variation in properties of the slag phase such as thickness, viscosity, density, etc. can have significant effect on slag 'eye' area.…”

Generation of Fine Bubbles, Metal Droplets, and Slag Droplets in Reactors Agitated by Bottom Gas Injection

“…Plume eye Spout eye [56][57][58][59][60][61][62][63][64][65][66][67] Spitting Splash Reverseemulsification [56][57][58][59][60][61][62][63][64][65][66][67] 3． 底吹き単孔ノズルによる気泡の生成ならびに それに伴う液滴の発生 3・1 単孔ノズルによる気泡の生成挙動 11,16,[19][20][21][22][23][24][25][26][27] Sano and Mori 4,6 Fig …”