Casting nozzle

Abstract

The present invention provides a casting nozzle that does not readily take in outside air, even when exposed wind. This casting nozzle 1 is formed such that a metal case 12 surrounds a nozzle body upper end part 111 that is an upper end part of a nozzle body 11, and the nozzle body upper end part 111 as surrounded by the metal case 12 is joined to a lower nozzle 2 that is attached to a lower part of a molten steel ladle or a tundish. The casting nozzle has a gas pool 13 that is provided between an outside surface of the nozzle body upper end part 111 and an inside surface of the metal case 12, a gas passage 14 that is provided between an upper end surface of the nozzle body upper end part 111 and the inside surface of the metal case 12 and communicates with the gas pool 13, and a gas discharge port 141 that is a tip-side opening of the gas passage 14 and discharges gas toward the lower nozzle 2. The metal case 12 has a hanging part 121 that hangs so as to guide gas discharged from the gas discharge port 141 downward.

Description

Casting Nozzle

[0001] The present invention relates to a casting nozzle used in continuous casting of molten steel.

[0002] In continuous casting of molten steel, when discharging molten steel from a molten steel ladle (ladle) to a tundish, in order to suppress oxidation of molten steel and entrainment of slag present on the upper surface in the tundish into the molten steel, it is common to join a long nozzle as a casting nozzle below a lower nozzle attached to the lower part of the molten steel ladle. In addition, when pouring molten steel from a tundish into a mold, it is common to join an immersion nozzle as a casting nozzle below a lower nozzle attached to the lower part of the tundish.

[0003] Hereinafter, among these casting nozzles, a long nozzle will be mainly taken as an example for description. The long nozzle is joined to the lower nozzle attached to the lower part of the molten steel ladle via a packing material or the like. Between the long nozzle and the lower nozzle, high adhesion (sealing performance) is required in order to suppress (a) mixing of air (oxygen, etc.) into molten steel, (b) leakage of molten steel from the joint, (c) wear caused by oxidation near the joint of the long nozzle and the lower nozzle made of carbon-containing materials, and the like. In addition, since the long nozzle is attached to and detached from the lower nozzle every time the molten steel ladle is replaced, this attachment and detachment is repeated for the number of times the molten steel ladle is replaced. At the joint between such a long nozzle and the lower nozzle, adhesion may decrease and a gap may be formed due to attachment / detachment work, adhesion of molten steel, slag, etc., damage to the nozzle, and the like. When such a gap is formed, the sealing performance decreases, and outside air is drawn into the nozzle, which increases the risk of causing oxidation of molten steel, damage due to oxidation of the nozzle made of carbon-containing refractory, and the like.

[0004] As one of the countermeasures, a method of discharging inert gas from the vicinity of the upper end of the long nozzle is adopted. For example, Patent Documents 1 to 3 disclose a long nozzle having a structure in which the upper end of a nozzle body made of a refractory material of the long nozzle is surrounded by a metal case, and gas is discharged toward the lower nozzle from a gas discharge port, which is a tip opening of a gas passage provided between the upper end surface of the upper end of the nozzle body and the inner surface of the metal case.

[0005] Japanese Patent Publication No. 2011-212721, Japanese Patent Publication No. 2014-133241, Japanese Patent Publication No. 2020-32430

[0006] The inventors conducted detailed on-site observations, including usage conditions, of a conventional casting nozzle having a structure in which gas is discharged from a sludge discharge port, which is the tip opening of a gas passage provided between the upper end surface of the upper end of the nozzle body and the inner surface of the metal case, toward the lower nozzle, as described above. They also conducted various simulations based on these usage conditions. As a result, it was found that in the casting site, the casting nozzle is constantly exposed to external winds generated by cooling air from a spot cooler when an operator approaches, and cooling air to the sliding nozzle device to which the lower nozzle is attached. The effect of the gas seal caused by the discharge of gas from the gas discharge port is weakened by the influence of this external wind, making it easier for outside air to be drawn into the nozzle.

[0007] Therefore, the problem that the present invention aims to solve is to provide a casting nozzle that is less prone to drawing in outside air even when exposed to external wind.

[0008] According to one aspect of the present invention, the following casting nozzle is provided: A casting nozzle having an upper end of a nozzle body surrounded by a metal case, wherein the upper end of the nozzle body surrounded by the metal case is joined to a lower nozzle attached to the lower part of a molten steel ladle or tundish, the casting nozzle having a gas pool provided between the outer surface of the upper end of the nozzle body and the inner surface of the metal case, a gas passage communicating with the gas pool and provided between the upper end surface of the upper end of the nozzle body and the inner surface of the metal case, and a gas outlet which is the tip-side opening of the gas passage and discharges gas toward the lower nozzle, the metal case is provided with a hanging portion that hangs down to guide the gas discharged from the gas outlet downward.

[0009] According to the present invention, by providing a hanging portion on the metal case, outside air is less likely to be drawn into the nozzle even when exposed to wind from the outside.

[0010] A cross-sectional view of the main part of a casting nozzle, which is one embodiment of the present invention. A cross-sectional view of the main part of the casting nozzle shown in Figure 1, showing the state when the metal case slides up. A diagram conceptually showing the simulation method and conditions performed to verify the effect of the hanging part. A diagram conceptually showing the various models used in the simulation shown in Figure 3. A diagram showing the results of simulating the flow of outside air and argon gas using the simulation shown in Figure 3 (when the crosswind is 1 m / min in models (a) and (b)). A diagram showing the results of simulating the flow of outside air and argon gas using the simulation shown in Figure 3 (when the crosswind is -1 m / min in models (a) and (b)). A diagram showing the results of simulating the flow of outside air and argon gas using the simulation shown in Figure 3 (when the crosswind is 1 m / min in models (c) and (d)). A diagram showing the results of simulating the flow of outside air and argon gas using the simulation shown in Figure 3 (when the crosswind is -1 m / min in models (c) and (d)). Figure 3 shows a graph illustrating the calculated amount of argon gas drawn in at the joint with the lower nozzle, based on the simulation.

[0011] Figure 1 shows a cross-sectional view of the main part of a casting nozzle, which is one embodiment of the present invention. The casting nozzle shown in the figure is a long nozzle 1, in which the upper end 111 of the nozzle body, which is the upper end of the nozzle body 11 made of refractory material, is surrounded by a metal case 12, and this upper end 111 of the nozzle body, surrounded by the metal case 12, is joined to a lower nozzle 2 attached to the bottom of a molten steel ladle (not shown).

[0012] The long nozzle 1 has a gas pool 13 provided between the outer surface of the upper end 111 of the nozzle body and the inner surface of the metal case 12, a gas passage 14 that communicates with the gas pool 13 and is provided between the upper end surface of the upper end 111 of the nozzle body and the inner surface of the metal case 12, and a gas outlet 141 which is the tip opening of the gas passage 14 and discharges gas toward the lower nozzle 2. The metal case 12 is provided with a hanging portion 121 that hangs down to guide the gas discharged from the gas outlet 141 downward. Reference numeral 15 in Figure 1 indicates a filler material (adhesive) filled between the outer surface of the upper end 111 of the nozzle body and the inner surface of the metal case 12, excluding the portion that forms the gas pool 13.

[0013] In this embodiment, multiple grooves 111a are provided radially on the upper end surface of the upper end portion 111 of the nozzle body. The gas passage 14 is composed of the multiple grooves 111a and the inner surface of the metal case 12, and multiple gas passages are provided radially corresponding to the multiple grooves 111a. Such a configuration of the gas passage 14 is a well-known configuration, as disclosed in, for example, the above-mentioned Patent Documents 2 and 3. However, the configuration of the gas passage in the present invention is not limited to this configuration, and for example, a configuration in which multiple spacers are interposed instead of multiple grooves 111a may be used, and in short, the gas passage only needs to be provided between the upper end surface of the upper end portion of the nozzle body and the inner surface of the metal case.

[0014] Next, the specific configuration of the hanging portion 121 will be described. In this embodiment, the hanging portion 121 is provided to hang down vertically downward in a curtain-like manner from the entire circumference of the inner edge of the metal case 12. However, the configuration of the hanging portion 121 is not limited to this configuration, and it may be provided intermittently in accordance with the multiple gas discharge ports 141, which are the tip-side openings of the multiple gas passages 14 provided radially. Also, the direction in which the hanging portion 121 hangs down is not limited to vertically downward, and it may be tapered to hang down in accordance with the shape of the joint with the lower nozzle 2, for example. In short, the hanging portion only needs to hang down in a way that guides the gas discharged from the gas discharge port downward.

[0015] The vertical length L of the hanging portion 121 is not particularly limited, but considering the sliding phenomenon of the metal case 12 described later, it is preferable that the vertical length L of the hanging portion 121 be 5 mm or more and 20 mm or less. Here, the vertical length L of the hanging portion 121 refers to the length from the inner surface of the metal case 12 to the lower end surface of the hanging portion 121, as shown in Figure 1. The sliding phenomenon of the metal case 12 is the phenomenon in which the metal case 12 slides upward relative to the upper end 111 of the nozzle body, as illustrated in Figure 2. This sliding phenomenon occurs due to the difference in thermal expansion between the metal case (metal) and the upper end of the nozzle body (refractory material), as well as when an upward force is applied to push up the upper end of the nozzle body surrounded by the metal case in order to join the casting nozzle to the lower nozzle. When the inventors investigated data on the sliding phenomenon of the metal case (amount of sliding of the metal case) for various casting nozzles, they found that it was generally about 2 to 4 mm. Furthermore, considering the sliding phenomenon (amount of sliding) of the metal case 12, it was found that the vertical length of the hanging portion is preferably 5 mm or more and 20 mm or less. However, this invention does not exclude cases where the vertical length of the hanging portion is less than 5 mm. Even if the vertical length of the hanging portion is less than 5 mm, the effects of this invention (that outside air is less likely to be drawn into the nozzle even when exposed to wind from the outside) can still be obtained to some extent compared to cases where there is no hanging portion.

[0016] Next, we will explain the simulations conducted to verify the effect of the hanging section. Figure 3 conceptually shows the simulation method and conditions. Figure 4 conceptually shows the various models used in the simulation. In the simulation, as conceptually shown in Figure 3, the gas (argon) supply rate to the casting nozzle was set to 250 L / min, and the suction rate at the joint with the lower nozzle was set to 30 L / min. The flow of outside air and argon gas was simulated using the models shown in Figures 4(a) to (d) for cases where the external wind (crosswind) was 1 m / min and -1 m / min. Here, the model in Figure 4(a) (hereinafter referred to as "model (a)") is a conventional casting nozzle without a hanging section, where the metal case slide phenomenon described above does not occur, while the model in Figure 4(b) (hereinafter referred to as "model (b)") is the case where the metal case slide phenomenon (slide amount = 4 mm) occurs in model (a). Furthermore, the model in Figure 4(c) (hereinafter referred to as "Model (c)") is a casting nozzle of the present invention equipped with a hanging portion (length L = 8 mm), in which there is no sliding phenomenon of the metal case. The model in Figure 4(d) (hereinafter referred to as "Model (d)") is in which the sliding phenomenon of the metal case (amount of sliding = 4 mm) occurs in Model (c).

[0017] Figures 5 to 8 show the simulation results for the flow of outside air and argon gas. Specifically, Figure 5 shows the simulation results for models (a) and (b) when the crosswind is 1 m / min, Figure 6 shows the simulation results for models (a) and (b) when the crosswind is -1 m / min, Figure 7 shows the simulation results for models (c) and (d) when the crosswind is 1 m / min, and Figure 8 shows the simulation results for models (c) and (d) when the crosswind is -1 m / min. Figure 9 shows the amount of argon gas drawn in at the joint with the lower nozzle, calculated from these simulation results. As mentioned above, the simulation assumed a suction amount of 30 L / min at the joint with the lower nozzle. Therefore, an argon gas intake of 30 L / min means that there is no outside air drawn into the nozzle, and as shown in Figure 9, this value (30 L / min) is the ideal value for the argon gas intake.

[0018] From Figures 5 to 8 and 9, it can be seen that, according to models (c) and (d), which are models of the casting nozzle of the present invention with a hanging section, compared to models (a) and (b), which are models of conventional casting nozzles without a hanging section, outside air is less likely to be drawn into the nozzle even when exposed to wind from the outside (crosswind) or when the metal case slides up.

[0019] In the embodiments described above, long nozzles were used as an example among casting nozzles, but the present invention can naturally be applied to immersion nozzles as well. Furthermore, the shape of the lower nozzles joined to these casting nozzles is not limited to the example in Figure 1, nor is the joining method between the casting nozzles and the lower nozzles limited to the example in Figure 1. In other words, known shapes and joining methods can be appropriately adopted.

[0020] 1 Long nozzle (casting nozzle) 11 Nozzle body 111 Upper end of nozzle body 111a Groove 12 Metal case 121 Hanging part 13 Gas pool 14 Gas flow path 141 Gas outlet 15 Filling material (adhesive) 2 Lower nozzle

Claims

1. A casting nozzle having a metal case surrounding the upper end of the nozzle body, which is the upper end of the nozzle body, and the upper end of the nozzle body surrounded by the metal case being joined to a lower nozzle attached to the lower part of a molten steel ladle or tundish, wherein the nozzle has a gas pool provided between the outer surface of the upper end of the nozzle body and the inner surface of the metal case, a gas passage that communicates with the gas pool and is provided between the upper end surface of the upper end of the nozzle body and the inner surface of the metal case, and a gas outlet which is the tip opening of the gas passage and discharges gas toward the lower nozzle, and the metal case is provided with a hanging part that hangs down to guide the gas discharged from the gas outlet toward the lower nozzle.

2. The casting nozzle according to claim 1, wherein the vertical length of the hanging portion is 5 mm or more and 20 mm or less.

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