Experiments on Removal of Hydrophilic Fine Particles in Bubbly Flow

Circular slits are introduced in purging plugs for alleviating the stress concentration to prolong their service life. Herein, the effects of slits with different geometries on the mixing time, inclusion removal rate, and slag eye area are studied by water model method. Experimental results show that the inclusion removal rate decreases with increasing slit angle for the gas flow rate of less than 6.02 NL min À1 . Moreover, with slit diameter increases, the mixing time and inclusion removal rate decrease when a gas flow rate is less than 5.26 NL min À1 . The slag eye area increases with increasing slit diameter, and the slit angle has a positive influence on the formation of the slag eye. Finally, the optimization of the mixing time and inclusion removal rate for less consumption of stirring energy and less slag entrapment indicates that the smaller the slag eye area is, the better the refining effect is.

μ m

are used to simulate actual inclusions of diameter ≈50

μ m

.…”

Section: Physical Modelingmentioning

confidence: 99%

η = \frac{ω_{d}}{ω_{0}}

where

ω_{normald}

is the weight of filtered particles, and

ω_{0}

is the weight of particles that were suspended in the water model.…”

Section: Physical Modelingmentioning

confidence: 99%

Physical Modeling Evaluation on Refining Effects of Ladle with Different Purging Plug Designs

Tan

Jin

et al. 2020

Section: Introductionmentioning

confidence: 99%

“…These processes realize the effects of steeling alloying, inclusion removal, deoxidation, desulfurization, and decarburization and improve the cleanliness of steel refining. [6][7][8] Therefore, optimizing the purging plug is key in regulating the flow of bubbles in the ladle to improve the refining effect. [9,10] Recently, various researchers have optimized the position of the purging plug, [11] number of purging plugs, [12,13] and angle of double bricks [14] to improve vortex distribution, shorten the alloy mixing time, reduce the steel temperature gradient, and improve the efficiency of the desulfurization and decarburization reactions.…”

mentioning

confidence: 99%

Numerical Study of the Bubble Behavior of a Ladle with Different Purging Plug Designs

Shang

Tan

et al. 2022

Ladle refining is widely applied to satisfy the demand for high-quality steel. A purging plug, a key component of ladle refining, is used for blowing argon into the molten steel to form upward-moving bubbles that drive the molten steel in a circular flow. [1][2][3] The circular flow carries inclusions to the slag layer. These inclusions are then adhered to the slag to remove them. [4,5] Meanwhile, nitrogen, hydrogen, and other harmful gases in the steel continue to diffuse to the low partial pressure bubble until the bubble escapes from the steel. These processes realize the effects of steeling alloying, inclusion removal, deoxidation, desulfurization, and decarburization and improve the cleanliness of steel refining. [6][7][8] Therefore, optimizing the purging plug is key in regulating the flow of bubbles in the ladle to improve the refining effect. [9,10] Recently, various researchers have optimized the position of the purging plug, [11] number of purging plugs, [12,13] and angle of double bricks [14] to improve vortex distribution, shorten the alloy mixing time, reduce the steel temperature gradient, and improve the efficiency of the desulfurization and decarburization reactions. It is possible to change the type of purging plug to obtain an optimal bubble distribution. [15] Moreover, removing inclusions is more effective because of the larger surface area of small bubbles. [16] However, in some studies, [17,18] the bubble was ejected from a surface, or others simulated the gas ejected from the outlet of the purging plug. The distribution of the circular slits of the purging plug significantly influenced the bubble size. [19] To obtain an ideal bubble size, Rana et al. [20] focused on the effect of circular slits spacing on the bubble size. They found that the smaller the spacing of the slits to bubble diameter ratio is, the easier it is for the bubble to coalesce. Wraith [21] observed that during the bubble detachment phase, the bubble size directly depends on the shape and geometry of the nozzle opening. In addition, Jiang et al. [22] reported that the number of slits in the porous nozzle also affects the size of the bubbles, which also affects whether and when the bubbles coalesce during the rise, thereby affecting the average size of bubbles in the ladle. [23] Therefore, the distribution of the slits of the purging plug cannot be neglected for the size of the initial bubbles. Furthermore, the evolution of the initial bubble also affects the average size of bubbles in the ladle.In this study, based on the discrete phase model (DPM) of ANSYS, a file is used to define the position of the bubble sprayed into the slits, initial bubble diameter, and flow rate. The volume

“…[7,8] Generally, gas bubbling [9,10] is a widely recognized methodology for the removal of small inclusions. Nonmetallic inclusions, nonwetted by liquid steel, can be attached on bubble surfaces [11][12][13] or captured by bubble wakes, [14,15] and then move upward to the top surface following with floating bubbles. Zhang and Thomas [16] developed numerical simulation to investigate the motion behaviors of inclusions under effects of fluid flow combined with bubble flotation.…”

Section: Introductionmentioning

confidence: 99%

Modeling of Flow Behaviors in a Swirling Flow Tundish for the Deep Cleaning of Molten Steel

Huang

Chang

Zou

et al. 2021

A swirling flow tundish is developed to deeply clean the liquid steel through enhancing the coalescence of inclusions. The swirling flow is generated using the gravitational energy of liquid steel, without any external energy. Inclusions will gather to the center of the swirling flow by centripetal force, due to the density difference between inclusions and liquid steel. Thus, small inclusions can coalesce into larger ones, and then float to the top surface by their self‐buoyance. Physical experiments are carried out in a 1/2.5 scale five‐strand tundish, to investigate flow characteristics in the swirling flow tundish, compared with that in the tundish with a conventional turbulent inhibitor. Numerical modeling is developed to evaluate the swirling strength of liquid flow in swirling chambers in different sizes, which is related to the effect of inclusion coalescence. The results reveal that swirling chamber in diameter of 700 mm produces the highest swirling flow strength. The swirling system can not only improve the flow field, with a 21.75% reduction of dead volume, but also uniform flow characteristics at each strand. In addition, the swirling chamber inhibits the normal impact of the reversed flow on tundish surface, which is beneficial for remaining a stable slag layer.