Papers by Keyword: Water Model

Abstract: With the development of socio-economic and science and technology, People are more strict to the requirement of steel quality. A physical model was established according to the “similarity theory” to simulate the real 180t RH-TB vacuum refining device. Liquid steel is simulated by Nacl solution, Fine inclusions is simulated by high density polypropylene less than 0.04mm in diameter. The influence regularity of treatment time, lift gas flow rate and method of addition, the amount and time of NaHCO₃ addition on the inclusions removal rate have been discussed, the optimal values for each influence factor have been found and can be used in optimizing the refining technology.

Abstract: As large flow rate of argon blowing in the process of bottom argon blowing ladle will cause severe fluctuations and sprays of molten steel, making the slags surface boiled and steel secondly oxidized, melting the refractory materials in the ladle, the flow rate of bottom argon blowing is limited, which will affect the efficiency of stirring. A 1:7 ratio ladle water model is established in the lab, and we will discuss how the diameter (d) of immersed tube, inserting depth (h) and the rate of bottom argon blowing affect the mixing time. The results show that the fluctuations on the steel surface can be diminished by the variations of diameters of immersed tube and inserting depth, the mixing time can be shorted by the increased flow rate of bottom argon blowing.

Abstract: In this paper is compared residence times of tundish equipped with Turbostop and tundish equipped with experimental swirl chamber. Set of measurements in this paper was performed in the Laboratory simulated flow processes (LSSP). Water model is assembled at scale 1:3 to original. Measurements were evaluated by graphical measuring of water conductivity variation at tundish inlet and outlet by adding potassium chloride into tundish inlet and visually where KMnO4 was used as an indicator.

Abstract: Optimization of FCD design in a single strand slab tundish producing stainless steel is carried out by physical modelling using a 0.4 scale water model and mathematical modelling study. Reducing the residual metal volume at the end of casting, promoting the near-surface plug flow for inclusions removal and improving the transient slab quality are concerned, the optimized FCD is two dams and an impact pad, among them the dam1 (close to ladle shroud) with two 30 degrees upward inclined drain holes, another dam2 (close to tundish exit) is bottom rectangular-grooved which is beneficial for reducing the residual metal volume. Besides, the height of impact pad and drain holes must be concerned simultaneously, in the present study the height is 20mm and 60mm, respectively. Compared with turbulence inhibitors, impact pad will decrease the melt exposed to air at the steady state of casting. The holes at the higher level of dam may cause slag entrapment during the refilling process of ladle change operation.

Abstract: The optimization of the location and height of weir & dam with drain holes in a single-strand continuous casting tundish was carried out from the view of fluid flow characteristics by physical modeling using a 0.4 scaled water model and mathematical modeling study. Considering simultaneously reducing the remaining melt, maximizing the plug flow and avoiding the short circuited flow, the dam with two upwardly inclined drain holes was optimized. The parameters such as location and height of weir & dam Lw/L, Ld/L, Hw/H and Hd/H are important to fluid flow in tundish. Among them, the location and height of dam were more critical to the overall fluid flow in tundish. The gap between weir and dam was also very important, the gap length that smaller than 0.266 will be preferred. The dead region behind the weir was enlarged and the tracer flow through the drain holes of dam was weakened as increasing the gap of weir and dam. In present study, the parameters of the optimized Case7 are Hw/H 0.448 (162/362), Hd/H 0.718 (260/362), Lw/L 0.4 (480/1200) and Ld/L 0.667 (800/1200). For the fluid flow field, the near surface flow which beneficial to inclusions removal existed both above the dam and through the upwardly inclined drain holes. While the case of bottom grooved dam used may lead to short circuited flow through the grooves.

Abstract: Considering the process conditions of the continuous billet casting, this paper has studied the slag entrapment behavior of molten steel in mold by using of a water model, and analyzed the influence rules of the submerged nozzle immersion depth, the electromagnetic stirring intensity and the mould flux viscosity on the slag entrapment in mold. The results show that the surface velocity in meniscus gradually increases with the stirring intensity increasing and the submerged nozzle immersion depth decreasing. When the submerged nozzle immersion depth is shallower, the mould flux viscosity is lower, and the stirring intensity is high, the interface turbulence of the liquid steel and slag is more severe, slag entrapment may occur in the extreme state. In order to avoid the slag entrapment in the working condition, it is necessary to increase the submerged nozzle immersion depth and decrease stirring intensity mildly.

Abstract: Water model experiments were carried out to understand the behavior of the bubble formation near the immersion nozzle, bubble rising velocity in the liquid. The critical state appeared when Fr number changed from 5 to 6 was described. The character of the critical phenomenon was whether the evident separation between two continuous bubbles or air masses appeared.

Abstract: The fluid flow in an 800 mm diameter bloom mold from two kinds of submerged entry nozzles (SEN) was investigated numerically with a mathematical model and experimentally in a water model. It was shown from the research results that the impacting depths measured in the water modeling experiments are in good agreement with the ones from the numerical calculation. The impacting depths obtained from the 4-port down 5° SEN are 140~220 mm at immersion depths from 100 to 180 mm, while those from 5-port up 5° SEN are 60~120 mm at immersion depths from 100 to 140 mm. There are an upper and a lower recirculating zone for these two SENs at the vertical section through a port center. Dimension of these two recirculating flow zones varies with the immersion depth of the SENs. At 100 mm immersion depth of the tow SENs the eye of the upper recirculating flow is not evident. The eyes of the upper recirculating flows for 5-port up 5° SEN are close to the SEN, while the ones for 4-port down 5° SEN are close to the mold wall. On the liquid surface in the mold, flow produced with the 4-port SEN creates 8 recirculating flow zones close to the SEN, while 10 recirculating flow zones close to the mold wall are formed with the 5-port SEN.

Abstract: With the increasing demand for high quality steel, various secondary refining techniques have been developed in the past decades. RH powder top blowing process (RH-PTB) is practiced in industry to decrease the impurity content of steel in a more economical way. In the present work, based on similarity theory, RH powder top blowing process was simulated by water model, and the effects of operating parameters on mixing time were investigated. The results show that the injected powder had a negligible effect on mixing time in RH-PTB, and the mixing time increases with top lance gas flowrate and decreases with lifting gas flowrate of up-leg. It was found that the mixing time was no longer decreasing as the lifting gas flowrate was over 15 L/min. Moreover, the height of top lance has some effect on mixing time in the reactor, and it should be adjusted to specific circumstances for purposes.

Abstract: Based on the slab caster mold of ChengGang Company as prototype, the water model with 1:1 scale was used to study the effects of casting speed、nozzle port angle、immersion depth、bottom structure、mold width and other parameters on the surface flow velocity of liquid steel in slab caster mold. The results show that the effect of casting speed is biggest and with increase in the casting speed, the surface flow velocity of liquid steel is prominently increased, when the mold width at 1650mm, the surface flow velocity from 0.04m/s to 0.1m/s with the casting speed from 0.7m/min increased to 1.4m/min