US20220161320A1

US20220161320A1 - Device for Preventing Ingress of Floating Matter on Free Surfaces of Ladle and Tundish During Continuous Casting Process

Info

Publication number: US20220161320A1
Application number: US17/434,851
Authority: US
Inventors: Il Seouk Park; Jong Hyeon Son; Jong Hui LEE
Original assignee: Industry Academic Cooperation Foundation of KNU
Current assignee: Industry Academic Cooperation Foundation of KNU
Priority date: 2019-03-04
Filing date: 2020-03-02
Publication date: 2022-05-26
Also published as: KR102184274B1; WO2020180063A1; KR20200106353A; CN114096361A

Abstract

A device for preventing ingress of floating matters on the free surfaces of a ladle and a tundish, each having a discharge port, during a continuous casting process according to an embodiment of the present invention is configured for installation at the discharge ports of the ladle and the tundish, and comprises: a disc-shaped plate; and a support part installed at the plate and configured to support the plate on a surface around each of the discharge ports of the ladle and the tundish, wherein each of the ratio of the radius of the discharge port of the ladle to the width of the plate and the ratio of the radius of the discharge port of the tundish to the width of the plate has a value equal to or greater than 1.

Description

TECHNICAL FIELD

The following description relates to a device for preventing ingress of floating matters on free surfaces of a ladle and a tundish during a continuous casting process.

BACKGROUND ART

Dimples are often found on a free surface when liquid in a container is drained or suctioned through a narrow port. When a swirling flow is caused by the Coriolis effect or external disturbance in the container, the dimple develops rapidly in a vertical direction, and reaches a discharge port or pump inlet. Such dimple penetration is called an air-core phenomenon. The air-core phenomenon during a liquid draining process results in serious problems for many industrial devices. For example, the air-core phenomenon generated by a swirling flow in a liquid propellant tank causes fluctuations in a fuel supply rate. Since an effective drainage area occupied by a fluid in a liquid phase is narrowed due to an air core, the fuel supply rate may be significantly reduced by the air-core phenomenon. In a sump pump station, an air core may be created by a swirling flow initiated by the operation of a pump. Air entrained in the pump may cause cavitation on pump blades, a reduction in pump efficiency, vibration, and noise. In addition, according to a tundish discharging process in a continuous casting process, a slag floating on a molten metal may be entrained as a slab due to the air-core phenomenon, which results in significant quality defects in steel products. Therefore, many studies have been made to prevent such an air-core phenomenon. For example, Korean Patent Application Publication No. 10-2011-0028023 discloses a device for preventing a vortex of a molten steel in a tundish.

DISCLOSURE OF INVENTION

Technical Subject

An aspect provides a device for preventing ingress of floating matters on free surfaces of a ladle and a tundish during a continuous casting process.

Technical Solutions

According to an aspect, there is provided a device for preventing ingress of floating matters on free surfaces of a ladle and a tundish, the ladle and the tundish each having a discharge port, during a continuous casting process the device configured for installation at the discharge ports of the ladle and the tundish, and including a disc-shaped plate, and a support part installed at the plate and configured to support the plate on a surface around each of the discharge ports of the ladle and the tundish. Each of a ratio of a width of the plate to a radius of the discharge port of the ladle and a ratio of the width of the plate to a radius of the discharge port of the tundish may have a value equal to or greater than 1.
Each of the ratio of the width of the plate to the radius of the discharge port of the ladle and the ratio of the width of the plate to the radius of the discharge port of the tundish may have a value equal to or greater than 2.
Each of the ratio of the width of the plate to the radius of the discharge port of the ladle and the ratio of the width of the plate to the radius of the discharge port of the tundish may have a value less than or equal to 8.
Each of the ratio of the width of the plate to the radius of the discharge port of the ladle and the ratio of the width of the plate to the radius of the discharge port of the tundish may have a value less than or equal to 4.
A ratio of a distance between surfaces around the plate and the discharge port to the radius of the discharge port of the ladle or a ratio of the distance between the surfaces around the plate and the discharge port to the radius of the discharge port of the tundish may have a value equal to or greater than 2.
The ratio of the distance between the surfaces around the plate and the discharge port to the radius of the discharge port of the ladle or the ratio of the distance between the surfaces around the plate and the discharge port to the radius of the discharge port of the tundish may have a value less than or equal to 4.
The support part may include a plurality of protruding elements protruding from the plate.
The plurality of protruding elements may be arranged to be spaced apart from each other in a circumferential direction with respect to a central portion of the plate.

Effects

The device according to an aspect may prevent ingress of float matter on free surfaces of a ladle and a tundish during a continuous casting process.
The effect of preventing ingress of floating matters on free surfaces of a ladle and a tundish during a continuous casting process of the device according to an aspect is not limited to those mentioned above, and other effects not mentioned can be clearly understood to those skilled in the art from the description below.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating a continuous casting process system including a device for preventing ingress of floating matters according to an example embodiment.

FIG. 2 is a perspective diagram illustrating a device for preventing ingress of floating matters according to an example embodiment.

FIG. 3 is a conceptual diagram illustrating a state in which a device for preventing ingress of floating matters according to an example embodiment is installed.

FIG. 4 is a diagram illustrating experimental equipment used to prove a technical effect of a device for preventing ingress of floating matters according to an example embodiment.

FIG. 5 is a graph illustrating a comparison of draining times and water heights according to changes in a height of a device for preventing ingress of floating matters from a bottom surface of a tank, derived using the experimental equipment of FIG. 4.

FIG. 6 is a graph illustrating a comparison of draining times and water heights according to changes in a width of a device for preventing ingress of floating matters from a bottom surface of a tank, derived using the experimental equipment of FIG. 4.

FIGS. 7A to 7C are graphs illustrating elapsed times of a water-air interface during drainage derived using the experimental equipment of FIG. 4, wherein FIG. 7A is a graph when there is no device for preventing ingress of floating matters, FIG. 7B is a graph when there is a device for preventing ingress of floating matters, the device having a width of 15 mm and a height of 10 mm, and FIG. 7C is a graph when there is a device for preventing ingress of floating matters, the device having a width of 30 mm and a height of 20 mm.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, example embodiments will be described in detail with reference to the illustrative drawings. Regarding reference numerals assigned to components in each drawing, it should be noted that the same components will be designated by the same reference numerals, wherever possible, even though they are illustrated in different drawings. In addition, in the description of the example embodiments, detailed description of well-known related configurations or functions will be omitted when it is deemed that such description interferes with the understanding of the example embodiments.
In addition, terms such as first, second, A, B, (a), (b), and the like may be used herein to describe components of the example embodiments. These terms are only used to distinguish one component from another component, and essential, order, or sequence of corresponding components are not limited by these terms. It will be understood that when one component is referred to as being “connected to”, “coupled to”, or “linked to” another component, one component may be “connected to”, “coupled to”, or “linked to” another component via a further component although one component may be directly connected to or directly linked to another component.
A component included in any one example embodiment and another component including a function in common with that of the component will be described using the same designation in other example embodiments. Unless otherwise indicated, a description of one example embodiment may be applied to other example embodiments, and a detailed description will be omitted in an overlapping range.
FIG. 1 is a diagram illustrating a continuous casting process system including a device for preventing ingress of floating matters according to an example embodiment.
Referring to FIG. 1, a continuous casting process system 10 according to an example embodiment may include a ladle 110, a tundish 120, a casting mold 130, and a device 140 that suppresses a swirling flow generated in the ladle 110 and the tundish 120 to prevent ingress (or entrainment) of floating matters on a free surface of the ladle 110 and a free surface of the tundish 120 into the casting mold 130. A first shroud 114 may be installed between the ladle 110 and the tundish 120, and a second shroud 124 may be installed between the tundish 120 and the casting mold 130. A first valve 116 that opens and closes a flow of a fluid on a flow path from the ladle 110 to the tundish 120 may be installed on the first shroud 114. A second valve 126 that opens and closes a flow of a fluid on a flow path from the tundish 120 to the casting mold 130 may be installed on the second shroud 124.
Devices for preventing ingress of floating matters 140 may be installed on a bottom surface of the ladle 110 and a bottom surface of the tundish 120 so as to be respectively adjacent to a discharge port 112 of the ladle 110 and a discharge port 122 of the tundish 120. Taylor vortex plays an important role in concentrating an axial momentum initiated by draining a fluid to a central portion of each of the ladle 110 and the tundish 120, and the strong axial momentum of the ladle 110 and the tundish 120 helps the growth of the Taylor vortex. Thus, the devices for preventing ingress of floating matters 140 that are respectively positioned adjacent (or directly) to the discharge ports 112 and 122 help to effectively block an interaction between the Taylor vortex and the axial momentum.
FIG. 2 is a perspective diagram illustrating a device for preventing ingress of floating matters according to an example embodiment, and FIG. 3 is a conceptual diagram illustrating a state in which the device for preventing ingress of floating matters according to an example embodiment is installed.
Referring to FIGS. 2 and 3, the device for preventing ingress of floating matters 140 according to an example embodiment may include a plate 142 and a support part 144.
The plate 142 may have a shape suitable for effectively retarding the generation of an air core. For example, the plate 142 may have a disk shape such as a circle, an ellipse or several polygons.
The support part 144 is configured to support the plate 142 on a bottom surface 51 of the ladle 110, in particular, the surface 51 around the discharge port 112 of the ladle 110. In addition, although not illustrated, the support part 144 is configured to support the plate 142 on a bottom surface of a tundish, in particular, a surface around a discharge port of the tundish.
The support part 144 may include a plurality of protruding elements 1441. The plurality of protruding elements 1441 may protrude from a lower surface of the plate 142. For example, the plurality of protruding elements 1441 may have a cylindrical shape. The plurality of protruding elements 1441 may be arranged to be spaced apart from each other in a circumferential direction with respect to a central portion of the plate 142. Alternatively, the plurality of protruding elements 1441 may be arranged in a matrix form on the lower surface of the plate 142.
In one example embodiment, a descending pattern of a fluid may depend on a width 2R of the plate 142. In a preferred example embodiment, the descending pattern of the fluid may depend on a ratio of the width 2R of the plate 142 to a width 2 r of the discharge port 112.
In one example embodiment, the descending pattern of the fluid may not depend on a distance h between the plate 142 and the surface S1. In other words, a height of the plate 142 from the surface S1 may not affect the descending pattern of the fluid.
FIG. 4 is a diagram illustrating experimental equipment used to prove a technical effect of a device for preventing ingress of floating matters according to an example embodiment.
Referring to FIG. 4, the experimental equipment used for a liquid drainage experiment is illustrated in order to prove the technical effect of the device for preventing ingress of floating matters according to an example embodiment. Air and water in a set ratio were contained inside a tank T. At this time, a discharge port was formed at the bottom of the tank T. For numerical analysis, a width of the discharge port was set to 10 mm, that is, a radius of the discharge port was set to 5 mm. Then, a width of the tank T was set to 90 mm, a height of the water contained in the tank T was set to 250 mm from the bottom, and a height of an air layer was set to 100 mm from a free surface of the water. Here, the free surface was implemented by removing an upper cover of the tank T. In addition, in order to implement a swirling flow phenomenon according to the drainage of water contained in the tank T, a motor M was connected to a shaft S connected to the tank T with a belt B, and the motor M was driven to rotate the tank T. In order to capture an instantaneous fluid drainage pattern, a CCD camera C acquired an image of the water contained in the tank T at a rate of 20 frames per second. A level of a liquid over time was measured by a computer P based on the image received from the CCD camera C. Finally, the device for preventing ingress of floating matters was placed adjacent to the discharge port of the tank as a prototype.
FIG. 5 is a graph illustrating a comparison of draining times and water heights according to changes in a height of a device for preventing ingress of floating matters from a bottom surface of a tank, derived using the experimental equipment of FIG. 4.
Referring to FIG. 5, a graph illustrates a comparison according to the presence or absence of the device for preventing ingress of floating matters and a comparison according to a height of the device for preventing ingress of floating matters having a consistent width. In the category, “Rot” means the rotation of a tank, and “Supp” means the device for preventing ingress of floating matters. Therefore, “No Rot” means that there is no rotation of the tank, and “No Supp” means that there is no device for preventing ingress of floating matters.
In a first case in which there is neither rotation of the tank nor device for preventing ingress of floating matters, the time required for the water from the tank to be completely drained, that is, the complete draining time, was about 21 seconds.
In a second case in which there is no device for preventing ingress of floating matters and there is rotation of the tank, a descent rate of a water level abruptly changed about 3 seconds after the drainage started. This is due to the ingress of air into the discharge port by the generation of an air core. A drain flow rate sharply decreased after the aforementioned time (about 3 seconds). In addition, the descent rate of the water level was slowed down. When compared to the first case, the complete draining time in the second case was almost doubled.
When there is the device for preventing ingress of floating matters, no abrupt change in the drain flow rate occurred, and the complete draining time significantly decreased relative to the second case. In addition, the instantaneous drain flow rate became more uniform over the entire draining time. This result showed that a fluid descending pattern according to the water level is not significantly affected by the height of the device for preventing ingress of floating matters.
FIG. 6 is a graph illustrating a comparison of draining times and water heights according to changes in a width of a device for preventing ingress of floating matters from a bottom surface of a tank, derived using the experimental equipment of FIG. 4.
Referring to FIG. 6, a graph illustrates a comparison according to the width of the device for preventing ingress of floating matters spaced apart from the bottom surface of the tank at a consistent height. Here, “width” means a maximum length in a horizontal direction of the device for preventing ingress of floating matters. Therefore, when the device for preventing ingress of floating matters has a circular disk shape, “width” may also be interpreted as “diameter”.
In the case in which a device for preventing ingress of floating matters, the device has a width of 5 mm, that is, the width of the device for preventing ingress of floating matters is relatively small compared to a radius of 5 mm of a discharge port, a water level descended at a significantly rapid rate for first about 4 seconds. As the width of the device for preventing ingress of floating matters increased relative to the radius of the discharge port of the tank, a sudden change in the water level during the initial drainage disappeared, and an initial descent rate of the water level significantly decreased. However, at about 17 seconds, water levels in the cases in which the device for preventing ingress of floating matters has a relatively large width (W=20 mm, 30 mm, 40 mm) exceeded water levels in the cases in which the device for preventing ingress of floating matters has a relatively small width (W=5 mm, 10 mm). As a result, despite a size of the device for preventing ingress of floating matters, the complete draining time decreased. This result means that when the device for preventing ingress of floating matters has a width of 20 mm or more, the width of the device for preventing ingress of floating matters hardly affects a descending pattern of the water level.
FIGS. 7A to 7C are graphs illustrating elapsed times of a water-air interface during drainage derived using the experimental equipment of FIG. 4, wherein FIG. 7A is a graph when there is no device for preventing ingress of floating matters, FIG. 7B is a graph when there is a device for preventing ingress of floating matters, the device having a width of 15 mm and a height of 10 mm, and FIG. 7C is a graph when there is a device for preventing ingress of floating matters, the device having a width of 30 mm and a height of 20 mm.
Referring to FIGS. 7A to 7C, in the case of FIG. 7A, it was confirmed that a dimple generated by the rotation of a tank was rapidly suctioned into a discharge port at about 3 seconds. During draining time, an air core remained. An air phase partially occupies a cross section of the discharge port, and thus a drain flow rate of water started to decrease after the generation of the air core.
In the case of FIG. 7B and the case of FIG. 7C, no sudden suction of the dimple occurred. A sloshing, that is, repeated up-and-down movement of a free surface, appeared in a central portion of the tank during drainage. However, when compared to the case of FIG. 7C, the case of FIG. 7B showed a slightly faster drop in a water level during an initial draining period. After about 4 seconds, a descent rate of the water level in the case of FIG. 7B significantly slowed down. However, the complete draining time in the case of FIG. 7B was longer than that in the case of FIG. 7C.
As described above, when the width of the device for preventing ingress of floating matters is in an appropriate range, it is possible to effectively retard the generation of the air core, and it can be confirmed that it is advantageous in terms of the draining rate and complete draining time of a fluid.
A number of example embodiments have been described above. Nevertheless, it should be understood that various modifications may be made to these example embodiments. For example, suitable results may be achieved if the described techniques are performed in a different order and/or if components in a described system, architecture, device, or circuit are combined in a different manner and/or replaced or supplemented by other components or their equivalents.

Claims

1. A device for preventing ingress of floating matters on free surfaces of a ladle and a tundish, the ladle and the tundish each having a discharge port, during a continuous casting process, the device configured for installation at the discharge ports of the ladle and the tundish, and comprising:

a disc-shaped plate; and

a support part installed at the plate and configured to support the plate on a surface around each of the discharge ports of the ladle and the tundish,

wherein each of a ratio of a width of the plate to a radius of the discharge port of the ladle and a ratio of the width of the plate to a radius of the discharge port of the tundish has a value equal to or greater than 1.

2. The device of claim 1, wherein each of the ratio of the width of the plate to the radius of the discharge port of the ladle and the ratio of the width of the plate to the radius of the discharge port of the tundish has a value equal to or greater than 2.

3. The device of claim 1, wherein each of the ratio of the width of the plate to the radius of the discharge port of the ladle and the ratio of the width of the plate to the radius of the discharge port of the tundish has a value less than or equal to 8.

4. The device of claim 3, wherein each of the ratio of the width of the plate to the radius of the discharge port of the ladle and the ratio of the width of the plate to the radius of the discharge port of the tundish has a value less than or equal to 4.

5. The device of claim 1, wherein a ratio of a distance between surfaces around the plate and the discharge port to the radius of the discharge port of the ladle or a ratio of the distance between the surfaces around the plate and the discharge port to the radius of the discharge port of the tundish has a value equal to or greater than 2.

6. The device of claim 5, wherein the ratio of the distance between the surfaces around the plate and the discharge port to the radius of the discharge port of the ladle or the ratio of the distance between the surfaces around the plate and the discharge port to the radius of the discharge port of the tundish has a value less than or equal to 4.

7. The device of claim 1, wherein the support part includes a plurality of protruding elements protruding from the plate.

8. The device of claim 7, wherein the plurality of protruding elements are arranged to be spaced apart from each other in a circumferential direction with respect to a central portion of the plate.