nozzle

Abstract

To provide a nozzle which enables a spray angle of a liquid mixed fluid from a nozzle hole to be set to various angles and can change a liquid injection amount while maintaining the set spray angle.SOLUTION: A nozzle includes a nozzle body 2 in which a liquid mixed fluid passage 5 extending in a perspective direction is formed. In the nozzle body 2, a groove 3 is formed at a distal side end surface. A nozzle hole 4 extending along an extending direction of the groove 3 is provided at a bottom part of the groove 3. The passage 5 has: a first space 5A; and a second space 5C located closer to the distal side than the first space 5A. The nozzle hole 4 is formed at a distal end part of the second space 5C. A constriction space 5B having a narrow passage width is provided between the first space 5A and the second space 5C. The constriction space 5B is formed so that the passage width spreads from the proximal side to the distal side.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a nozzle, and more particularly to a two-fluid nozzle capable of spraying a gas-liquid mixed fluid in a generally fan-shaped manner. [Background technology]

[0002] Various types of two-fluid nozzles that spray a gas-liquid mixture in a generally fan-shaped manner have been known. For example, Patent Document 1 discloses a gas-liquid mixture spray nozzle having a nozzle formed at the bottom of a bottomed cylindrical nozzle body that can atomize and spray the gas-liquid mixture in a flat state, and a throttle portion formed in the nozzle body that has a first raised surface that protrudes radially inward from the inner circumferential surface on the upstream side in the flow direction of the gas-liquid mixture and a second raised surface that protrudes radially inward from the inner circumferential surface on the downstream side in the flow direction of the gas-liquid mixture. Patent Document 2 discloses a nozzle in which a flow path is provided along the central axis of the nozzle body from an inlet at one end to an injection hole at the other end, the injection side tip of the flow path being an arc-shaped main hole, a diametrical notch is provided on the flat surface of the injection side tip, the notch is inclined in the depth direction from both diametrical ends towards the center, the center of the notch is connected to the tip of the main hole, an elongated injection hole is provided that is long in the notch direction and narrow in the perpendicular direction, an orifice is provided at the inlet to the main hole, and the width of the flow path reaching the injection hole is narrowed by the orifice, then widened by the main hole, and then narrowed again by the injection hole. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Utility Model Application Publication No. 61-118665 [Patent Document 2] Japanese Patent Application Laid-Open No. 2008-296197 Summary of the Invention [Problem to be solved by the invention]

[0004] Nozzles that spray a gas-liquid mixture in a generally fan-shaped manner are used, for example, to cool continuously cast strands in continuous casting machines. In the secondary cooling zone of a continuous casting facility, the continuously cast strand is conveyed between multiple rolls, and water is sprayed onto the conveyed continuously cast strand to cool it. In this process, it is desirable to appropriately set the spray range from the nozzle depending on the width and thickness of the continuously cast strand being conveyed, and to spray water as evenly as possible within a predetermined range in the spray width direction. This facilitates controlling the cooling of the continuously cast strand and reduces cooling unevenness. Furthermore, the cooling temperature must be adjusted depending on the conveying speed and conveying area of ​​the continuously cast strand, and also depending on the steel grade. Therefore, it is desirable for nozzles used in the secondary cooling zone of a continuous casting facility to maintain a predetermined spray angle even when the amount of sprayed water is changed.

[0005] On the other hand, because the width and thickness of continuously cast slabs vary depending on the steel grade, when multiple types of steel are produced using a single continuous casting facility, it is necessary to appropriately set the injection angle and injection range for each steel grade. The injection angle and injection range from the nozzle can be changed, for example, by changing the nozzle distance from the continuously cast slab or by changing the type of nozzle installed. However, this requires changing the nozzle installation conditions and type depending on the steel grade being produced, which leads to a decrease in production efficiency. Therefore, it would be desirable to be able to variably set the injection angle (injection range) of the gas-liquid mixture injected from the nozzle hole depending on the width and thickness of the continuously cast slab by adjusting the supply conditions of the gas-liquid mixture without changing the nozzle installation conditions or type, and to be able to change the amount of liquid injected while maintaining the set injection angle.

[0006] The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a nozzle that can set various injection angles of a gas-liquid mixture fluid from an injection port, and that can change the amount of liquid injected while maintaining the set injection angle. [Means for solving the problem]

[0007] The present invention includes the following inventions. [1] A nozzle having a nozzle body with a flow path for a gas-liquid mixture fluid formed therein, extending in a near-far direction, wherein a groove is formed on the distal end face of the nozzle body, and a nozzle is provided at the bottom of the groove, extending along the direction of extension of the groove, wherein the flow path has a first space and a second space distal to the first space, the nozzle is formed at the distal end of the second space, and a throttle space with a narrow flow path width is provided between the first space and the second space, and the throttle space is formed so that the flow path width increases from the proximal side to the distal side. [2] The nozzle according to [1], wherein the throttle space is formed in a circular or elliptical shape that is long in the extension direction of the groove when viewed from the distal or proximal side. [3] The nozzle according to [1] or [2], wherein the ratio S1 / S2 of the area S1 of the nozzle hole to the area S2 of the narrowest part of the throttling space is 0.7 or more and 1.5 or less. [4] The nozzle according to any one of [1] to [3], wherein the length of the throttle space in the perspective direction is 2 mm or more and 10 mm or less. [5] The nozzle according to any one of [1] to [4], wherein the outer peripheral surface of the throttle space is formed to have an inclination angle of 10° or more and 60° or less with respect to the perspective direction. [6] A nozzle described in any one of [1] to [5], wherein the second space is formed such that, at the position in the far direction where the nozzle is formed, its length in the direction perpendicular to the extension direction of the groove is longer than its length in the direction perpendicular to the extension direction. [7] The nozzle according to any one of [1] to [6], wherein the second space is provided with a step portion in which the width of the flow path narrows in a step-like manner from the proximal side to the distal side. [8] A continuous casting apparatus equipped with the nozzle according to any one of [1] to [7], characterized in that the nozzle is arranged facing the continuously cast slab so that the extension direction of the groove is approximately perpendicular to the transport direction of the continuously cast slab. [9] The continuous casting device described in [8] has a plurality of fixed rolls arranged opposite one main surface of the continuously cast slab along the conveying direction of the continuously cast slab, and a plurality of variable rolls arranged opposite the other main surface, and the nozzle is arranged opposite one or more surfaces selected from the one main surface of the continuously cast slab, the other main surface of the continuously cast slab, and a side surface between the one main surface and the other main surface of the continuously cast slab. [Effects of the Invention]

[0008] According to the nozzle of the present invention, by adjusting the supply conditions of the gas-liquid mixture fluid, it is possible to set various injection angles of the gas-liquid mixture fluid from the nozzle, and further, it is possible to change the amount of liquid injected while maintaining the set injection angle. [Brief explanation of the drawings]

[0009] [Figure 1] 1 shows an example of a nozzle of the present invention, and is a perspective view of the nozzle. [Figure 2] 2(a) shows a cross-sectional view of the nozzle shown in FIG. 1 taken along line AA, and FIG. 2(b) shows a cross-sectional view of the nozzle shown in FIG. 1 taken along line BB. [Figure 3] FIG. 2 shows an external view of the nozzle shown in FIG. 1 as seen from the distal side (the nozzle side). [Figure 4] 1 shows the measurement results of the flow rate distribution in the jet width direction when water is jetted from a nozzle of the present invention and a comparative nozzle under conditions of a wide jet angle. [Figure 5] 1 shows the measurement results of flow rate distribution in the jet width direction when water is jetted from a nozzle of the present invention and a comparative nozzle under conditions of a narrow jet angle. [Figure 6] FIG. 6(a) shows a modified example of the AA cross section of the nozzle shown in FIG. 1, and FIG. 6(b) shows a modified example of the BB cross section of the nozzle shown in FIG. [Figure 7] FIG. 7 is a perspective view of an orifice member provided in the nozzle shown in FIG. 6. [Figure 8] FIG. 8(a) shows a modified example of the AA cross section of the nozzle shown in FIG. 1, and FIG. 8(b) shows a modified example of the BB cross section of the nozzle shown in FIG. [Figure 9] 1 shows an example of application of the nozzle of the present invention to a continuous casting facility, and is a schematic diagram of a secondary cooling zone of the continuous casting facility. [Figure 10] 1 is a schematic diagram of a continuous casting facility and a cracking furnace used in the examples. [Figure 11] 1 shows the measurement results of flow rate distribution in the nozzle jet width direction in Test Nos. 1 to 4 of the example. [Figure 12] 1 shows the measurement results of flow rate distribution in the nozzle jet width direction in Test Nos. 5 to 8 of the example. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention relates to a nozzle capable of spraying a gas-liquid mixture in a generally fan-shaped manner. The nozzle of the present invention can change the spray angle (spray range) from the nozzle by adjusting the supply pressure of the gas or liquid, and can also change the amount of liquid sprayed while maintaining a predetermined spray angle. For example, when performing secondary cooling of a continuously cast slab in a continuous casting machine, the nozzle of the present invention can appropriately set the spray range from the nozzle according to the width and thickness of each continuously cast slab, and can also spray different amounts of water, without changing the nozzle installation conditions or type, even when different steel types are produced using a single continuous casting facility. Therefore, by appropriately adjusting the supply conditions of the gas-liquid mixture to the nozzle, it is possible to appropriately cool the continuously cast slab for various types of continuously cast slab. The nozzle of the present invention will be described below with reference to the drawings. Note that the present invention is not limited to the embodiments shown in the drawings.

[0011] Figures 1 to 3 show examples of the configuration of a nozzle of the present invention. Figure 1 shows a perspective view of the nozzle, Figure 2(a) shows a cross-sectional view of the nozzle shown in Figure 1 taken along line AA, Figure 2(b) shows a cross-sectional view of the nozzle shown in Figure 1 taken along line BB, and Figure 3 shows an external view of the nozzle shown in Figure 1 as seen from the distal side (nozzle side).

[0012] The nozzle 1 (1A) has a nozzle body 2 in which a flow path 5 for a gas-liquid mixed fluid is formed. The flow path 5 extends in the direction away from the nozzle body 2, and an inlet 6 for the gas-liquid mixed fluid is provided on the proximal side of the nozzle body 2, and an outlet 4 for spraying the gas-liquid mixed fluid is provided on the distal side of the nozzle body 2. The gas-liquid mixed fluid introduced into the nozzle body 2 from the inlet 6 flows through the flow path 5 from the proximal side to the distal side, and is sprayed out of the nozzle 1 from the outlet 4.

[0013] A groove 3 is formed on the distal end surface of the nozzle body 2, and an orifice 4 is provided at the bottom of the groove 3 so as to extend along the extension direction of the groove 3. By forming the orifice 4 in this manner, the gas-liquid mixture fluid can be sprayed in a substantially fan shape. In the present invention, the extension direction of the groove 3 in a plane perpendicular to the far-away direction is referred to as direction X, and the direction perpendicular to the extension direction of the groove 3 is referred to as direction Y.

[0014] The distal end surface of nozzle body 2 may be formed flat or curved, but is preferably formed flat as shown in Figure 1, and a groove 3 is preferably formed in the flat distal end surface of nozzle body 2. Groove 3 is preferably formed to extend linearly in direction X, and preferably extends across the distal end surface of nozzle body 2 to the side surface of nozzle body 2.

[0015] The groove 3 may be formed with the same width along the direction X, or may be formed so that its width increases with increasing distance from the nozzle 4 (see FIG. 3). The width of the groove 3 (length in the direction Y) is, for example, preferably 1 mm or more, more preferably 2 mm or more, and preferably 5 mm or less, more preferably 4 mm or less.

[0016] The groove 3 is preferably formed so that its depth increases from both ends in the X direction toward the nozzle 4. This prevents the spray angle from becoming too wide when the gas-liquid mixture fluid is sprayed from the nozzle 4, even if the spray conditions are changed. The bottom of the groove 3 is preferably inclined linearly proximally toward the nozzle 4. The depth of the groove 3 is, for example, preferably 1 mm or more, more preferably 2 mm or more, and preferably 10 mm or less, and more preferably 8 mm or less.

[0017] The cross-sectional shape of groove 3 in a direction perpendicular to direction X is not particularly limited. The cross section of groove 3 may be formed, for example, in a U-shape, a V-shape, or a rectangular shape (such as a square, a rectangle, or a trapezoid wider on the distal side). It is preferable that groove 3 be formed with the same width or with the width increasing from the proximal side to the distal side.

[0018] An orifice 4 is provided at the bottom of the groove 3. The orifice 4 is connected to the distal end of a flow path 5 for the gas-liquid mixture fluid inside the nozzle body 2. The orifice 4 is formed with a shape that is elongated in the X direction, i.e., longer in the X direction than in the Y direction. The length of the orifice 4 in the X direction is preferably, for example, 3 mm or more, more preferably 5 mm or more, and preferably 15 mm or less, more preferably 12 mm or less, and even more preferably 10 mm or less. The width of the orifice 4 is preferably the same as the width of the groove 3, and the length of the orifice 4 in the Y direction is, for example, preferably 1 mm or more, more preferably 2 mm or more, and preferably 5 mm or less, and more preferably 4 mm or less. The ratio L1 / W1 of the length L1 of the orifice 4 in the X direction to the length W1 of the orifice 4 in the Y direction is preferably 1.5 or more, more preferably 2.0 or more, and preferably 8.0 or less, more preferably 6.0 or less.

[0019] A supply pipe for a gas-liquid mixed fluid is connected to the inlet 6 on the proximal side of the nozzle body 2, and this supply pipe is provided with a gas supply unit and a liquid supply unit. By adjusting the gas supply pressure from the gas supply unit and the liquid supply pressure from the liquid supply unit, respectively, a gas-liquid mixed fluid of any gas-liquid ratio can be introduced into the nozzle body 2 through the supply pipe. A flow straightening member may be provided in the supply pipe for the gas-liquid mixed fluid. Note that the gas is preferably introduced into the supply pipe for the gas-liquid mixed fluid in a compressed state, which allows for a gas-liquid mixed fluid in which the gas and liquid are more uniformly mixed.

[0020] 2, the flow path 5 of the nozzle body 2 has a first space 5A and a second space 5C distal to the first space 5A, and a throttle space 5B where the flow path width is narrowed is provided between the first space 5A and the second space 5C. The nozzle orifice 4 is formed at the distal end of the second space 5C, and the gas-liquid mixture fluid that has passed through the first space 5A, the throttle space 5B, and the second space 5C is sprayed from the orifice 4 to the outside of the nozzle 1. The inlet 6 of the nozzle body 2 is preferably formed at the proximal end of the first space 5A.

[0021] The throttle space 5B is formed to have a narrower flow path width than the first space 5A and the second space 5C. Specifically, the throttle space 5B is formed to have a narrower flow path width than the distal end of the first space 5A and the proximal end of the second space 5C. The throttle space 5B is provided as an orifice in the flow path 5. By providing the throttle space 5B, the flow of the gas-liquid mixture fluid toward the nozzle 4 inside the nozzle body 2 is regulated (flow rectification effect), and the gas and liquid are intimately mixed while the gas-liquid mixture fluid passes from the first space 5A to the second space 5C, and the gas-liquid mixture fluid can be ejected from the nozzle 4 in this state. Therefore, even if the gas-liquid ratio (gas flow rate / liquid flow rate) of the gas-liquid mixture fluid is high, it is possible to prevent the gas from being distributed unevenly toward the outer portion of the flow path 5, and it becomes possible to eject the liquid more evenly in the ejection width direction.

[0022] The throttle space 5B is formed so that the width of the flow path increases from the proximal side to the distal side. By forming the throttle space 5B in this way, it is possible to change the spray angle (spray range) of the gas-liquid mixture fluid from the nozzle 4 with one nozzle, and also to change the amount of liquid sprayed while maintaining the set spray angle.

[0023] Figures 4 and 5 show the measurement results of the flow rate distribution in the jet width direction (i.e., the direction in which the flow spreads in an approximately fan shape) when a gas-liquid mixture consisting of air and water is jetted using nozzle A, in which the throttle space is formed so that the flow path width increases from the proximal side to the distal side, and nozzle B, in which the throttle space is formed so that the flow path width is constant from the proximal side to the distal side, while varying the air and water supply pressures. In Figures 4 and 5, graphs A1 to A4 represent the measurement results of the flow rate distribution for nozzle A, and graphs B1 to B4 represent the measurement results of the flow rate distribution for nozzle B. Figure 4 shows the results when water is jetted from the nozzle under conditions that result in a wide jet angle (conditions under which the gas-liquid supply pressure is high), and Figure 5 shows the results when water is jetted from the nozzle under conditions that result in a narrow jet angle (conditions under which the gas-liquid supply pressure is low).

[0024] Table 1 below summarizes the results of each injection condition shown in Figures 4 and 5, along with the injection angle and injection width at that time. The injection angle and injection width were determined as follows: the nozzle was installed at a height of 100 mm, water was injected from it, and the flow rate distribution in the injection width direction was measured. When the flow rate at the point with the highest flow rate was taken as 100%, the distance from directly below the nozzle to the points (two points on one side and one on the other) where the flow rate was 30% was determined, and the distance between these two points was taken as the injection width, and the angle formed by the line segment connecting the tip of the nozzle and these two points was taken as the injection angle.

[0025] [Table 1]

[0026] As can be seen from the results shown in Figures 4 and 5 and Table 1, when Nozzle A was used, the spray angle and spray width remained nearly constant even when the water jet rate was changed from 1.5 L / min to 10.5 L / min under wide spray angle conditions (A-1, A-2). The spray angle and spray width remained nearly constant even when the water jet rate was changed from 1.2 L / min to 8.4 L / min under narrow spray angle conditions (A-3, A-4). In contrast, when Nozzle B was used, the spray angle and spray width fluctuated significantly when the water jet rate was changed from 1.5 L / min to 10.5 L / min under wide spray angle conditions (B-1, B-2). The spray angle and spray width also fluctuated significantly when the water jet rate was changed from 1.2 L / min to 8.4 L / min under narrow spray angle conditions (B-3, B-4).

[0027] With Nozzle B, the injection angle narrowed as the gas-liquid ratio increased, and the flow rate distribution in the injection width direction showed a particularly large flow rate directly below the nozzle. In contrast, with Nozzle A, the injection angle remained nearly constant even as the gas-liquid ratio increased, and the liquid was injected more evenly in the injection width direction. This is thought to be because, with Nozzle A, the throttle space is designed to widen from the proximal to the distal side, making it easier for the liquid to spread along the outer periphery of the throttle space, even when the gas-liquid ratio increased and the proportion of liquid in the gas-liquid mixture decreased. Therefore, with Nozzle A, even under injection conditions with a high gas-liquid ratio, the amount of injection was secured to a position away from the nozzle in the injection width direction, and the injection angle and injection range were not significantly reduced compared to when the gas-liquid ratio was low. Thus, by using the nozzle of the present invention, it is possible to vary the injection angle (injection range) with a single nozzle, and the set injection angle can be maintained even when the injection water volume is changed.

[0028] The shape of the throttle space 5B is not particularly limited. However, it is preferable that the throttle space 5B be formed into a circular shape or an elliptical shape that is long in the direction X when viewed from the distal side or the proximal side. It is preferable that the throttle space 5B be formed into such a shape at its narrowest point in the perspective direction, and that the throttle space 5B be formed into such a shape throughout the perspective direction. The elliptical shape is not particularly limited as long as the outer edge is formed of a curve or a combination of curves and straight lines and has no corners, and includes an ellipse, a rounded rectangle, an oval, and the like. Forming the throttle space 5B into such a shape enhances the rectification of the gas-liquid mixture fluid in the throttle space 5B. In particular, forming the throttle space 5B into an elliptical shape that is long in the direction X is preferable because it further rectifies the flow of the gas-liquid mixture fluid in the range from the throttle space 5B to the nozzle 4. This allows the liquid to be sprayed more uniformly in the spray width direction from the nozzle 4. The ratio L2 / W2 of the length L2 in the direction X of the narrowest part of the aperture space 5B to the length W2 in the direction Y is preferably 1.0 or more, more preferably 1.2 or more, and even more preferably 1.5 or more, and is preferably 5.0 or less, and more preferably 4.0 or less.

[0029] The throttle space 5B is preferably formed so that its flow path width is narrower than the first space 5A and the second space 5C in both the direction X and the direction Y, and is preferably formed so that its flow path width is narrower than the first space 5A and the second space 5C around the entire circumference about the far-away direction. This enhances the mixing effect of the gas and liquid in the gas-liquid mixture fluid when it passes through the throttle space 5B. From the same perspective, the throttle space 5B is preferably formed so that the flow path 5B narrows in a stepped manner at the boundary with the first space 5A and the boundary with the second space 5C.

[0030] The throttle space 5B is preferably formed so that the area of ​​its narrowest part in the far-to-near direction is approximately the same as the area of ​​the nozzle hole 4. If the throttle space 5B and the nozzle hole 4 are formed in this manner, the flow of the gas-liquid mixture fluid is suitably rectified in the range from the throttle space 5B to the nozzle hole 4. For example, the ratio S1 / S2 of the area S1 of the nozzle hole 4 to the area S2 of the narrowest part of the throttle space 5B is preferably 0.7 or more, more preferably 0.8 or more, and is preferably 1.5 or less, more preferably 1.4 or less.

[0031] The ratio L1 / L2 of the length L1 in the X direction of the nozzle hole 4 to the length L2 in the X direction of the narrowest part of the throttle space 5B is preferably 0.8 or more, more preferably 0.9 or more, and is preferably 1.3 or less, and more preferably 1.2 or less. The ratio W1 / W2 of the length W1 in the Y direction of the nozzle hole 4 to the length W2 in the Y direction of the narrowest part of the throttle space 5B is preferably 0.4 or more, more preferably 0.5 or more, and is preferably 1.1 or less, more preferably 1.0 or less, and even more preferably 0.9 or less.

[0032] The length L2 of the narrowest part of the aperture space 5B in the direction X is, for example, preferably 3 mm or more, more preferably 5 mm or more, and preferably 15 mm or less, more preferably 12 mm or less, and even more preferably 10 mm or less. The length W2 of the narrowest part of the aperture space 5B in the direction Y is, for example, preferably 2 mm or more, more preferably 3 mm or more, and preferably 6 mm or less, and more preferably 5 mm or less.

[0033] The length T2 of the throttle space 5B in the distance direction is preferably 2 mm or more, more preferably 3 mm or more, and preferably 10 mm or less, and more preferably 8 mm or less. By setting the length T2 of the throttle space 5B in the distance direction to 2 mm or more, it becomes easy to form the throttle space 5B so that the flow path width increases from the proximal side to the distal side, and the liquid easily spreads along the outer peripheral surface when the gas-liquid mixture fluid passes through the throttle space 5B. By setting the length T2 of the throttle space 5B in the distance direction to 10 mm or less, the mixing effect of the gas-liquid mixture fluid by providing the throttle space 5B is enhanced.

[0034] The ratio S2 / (T2) of the area S2 of the narrowest part of the aperture space 5B to the square of the length T2 of the aperture space 5B in the perspective direction 2 is preferably 0.5 or more, more preferably 1.0 or more, even more preferably 1.2 or more, and is preferably 5.0 or less, more preferably 4.0 or less, and even more preferably 3.0 or less. By forming the throttle space 5B in this manner, a rectifying action is ensured when the gas-liquid mixture fluid passes through the throttle space 5B, and the gas-liquid mixing effect of the gas-liquid mixture fluid is easily enhanced.

[0035] The throttle space 5B is preferably formed so that the flow path width increases at least from the proximal side to the distal side in the direction X, and more preferably so that the flow path width increases from the proximal side to the distal side in both the direction X and the direction Y. It is particularly preferable that the throttle space 5B is formed so that the flow path width increases from the proximal side to the distal side around the entire circumference with the far-to-far direction as the axis.

[0036] The throttle space 5B, which is formed so that the flow path width increases from the proximal side to the distal side, may have an outer circumferential surface (i.e., the inner surface of the nozzle body 2 that surrounds the throttle space 5B with the distance direction as its axis) that is inclined or may be formed in a multi-stepped shape. In the former case, the outer circumferential surface of the throttle space 5B may be inclined linearly or curvedly inclined in a cross section along the distance direction, but is preferably inclined linearly. In the latter case, it is preferably formed in three or more steps, i.e., so that the flow path width increases in three or more stages. Note that, from the viewpoint that the liquid easily spreads along the outer circumferential surface when the gas-liquid mixture fluid passes through the throttle space 5B, it is preferable that the outer circumferential surface of the throttle space 5B is formed in an inclined shape.

[0037] The outer peripheral surface of the throttle space 5B preferably has an inclination angle of 10° or more with respect to the approach direction, more preferably 20° or more, and preferably 60° or less, more preferably 50° or less. When the outer peripheral surface of the throttle space 5B is formed in an inclined shape, the inclination angle refers to the inclination angle of the inclined outer peripheral surface. When the outer peripheral surface of the throttle space 5B is formed in a stepped shape with multiple steps, the inclination angle refers to the inclination angle of the plane connecting the apexes of the steps. If the throttle space 5B is formed in this manner, the liquid will easily spread along the outer peripheral surface when passing through the throttle space 5B. Preferably, the outer peripheral surface of the throttle space 5B is formed in an inclined shape with an inclination angle with respect to the approach direction within the above range.

[0038] The shape of the first space 5A is not particularly limited, and may be, for example, a cylinder, a truncated cone, a multi-stage cylinder, or a shape combining a cylinder and a truncated cone. The first space 5A is formed so that at least the distal end has a wider flow path width than the throttle space 5B, but it is preferable that the first space 5A is formed so that the flow path width is wider than the narrowest part of the throttle space 5B throughout the entire distal / near direction. Note that when a supply pipe for a gas-liquid mixture fluid is connected to the inlet 6 of the nozzle body 2 and the supply pipe is inserted into the flow path 5 of the nozzle body 2, the shape of the first space 5A is determined with the supply pipe inserted into the flow path 5 of the nozzle body 2.

[0039] The flow path width of the first space 5A (the flow path width at the widest part in the perspective direction) is, for example, preferably 10 mm or more, more preferably 12 mm or more, and is preferably 30 mm or less, more preferably 25 mm or less, and even more preferably 20 mm or less.

[0040] The shape of the second space 5C is not particularly limited, but it is preferable that the distal end of the second space 5C is formed so that the flow path width narrows toward the nozzle 4. In this case, it is preferable that the second space 5C is formed so that the flow path width narrows at least from the proximal side to the distal side in the direction X, and it is more preferable that the flow path width narrows from the proximal side to the distal side in both the direction X and the direction Y. This makes it possible to spray the gas-liquid mixture fluid from the nozzle 4 while increasing the pressure. It is preferable that the distal end of the second space 5C is formed, for example, in an arc shape when viewed in cross section along the perspective direction (i.e., it narrows in a curved shape that bulges outward in the directions X and Y toward the nozzle 4).

[0041] The shape of the second space 5C other than the distal end, for example, the vertical cross-sectional shape of the second space 5C proximal to the nozzle hole 4, may be a circle, an oval, a rectangle, a hexagon, an octagon, or a shape in which a plurality of these shapes are connected side by side. The vertical cross-sectional shape of the second space 5C may change depending on the position of the second space 5C in the cross-sectional direction.

[0042] The second space 5C is preferably provided with a step 7 in which the flow path width narrows in a step from the proximal side to the distal side. Providing the step 7 improves the mixing effect of the gas-liquid mixture fluid in the second space 5C. When the second space 5C is provided with the step 7, the flow path width of the second space 5C distal to the throttle space 5B and proximal to the step 7 is preferably formed wider than the flow path width at the distal end of the throttle space 5B over the entire distance direction.

[0043] The flow path width of the second space 5C (the flow path width at the widest part in the perspective direction) is, for example, preferably 10 mm or more, more preferably 12 mm or more, and preferably 30 mm or less, more preferably 25 mm or less, and even more preferably 20 mm or less. The length of the second space 5C in the perspective direction is, for example, preferably 5 mm or more, more preferably 8 mm or more, and preferably 25 mm or less, more preferably 20 mm or less, and even more preferably 15 mm or less.

[0044] Other configuration examples of the nozzle of the present invention are shown in Figures 6 and 7. Figure 6(a) shows a modified example of the AA cross section of the nozzle shown in Figure 1, Figure 6(b) shows a modified example of the BB cross section of the nozzle shown in Figure 1, and Figure 7 shows a perspective view of an orifice member that forms a throttled flow path.

[0045] 6 and 7 is formed by fitting an orifice member 8 inside a nozzle body 2. The orifice member 8 is provided with an opening 9 whose flow path width increases from the proximal side toward the distal side, and this opening 9 serves as a throttled flow path 5. By forming the nozzle 1B in this manner, a throttle space 5B can be easily formed in the flow path 5 inside the nozzle body 2.

[0046] Figure 8 shows yet another example of the configuration of the nozzle of the present invention. Figure 8(a) shows a modified example of the AA cross section of the nozzle shown in Figure 1, and Figure 8(b) shows a modified example of the BB cross section of the nozzle shown in Figure 1.

[0047] The nozzle 1 (1C) shown in Fig. 8 differs from the nozzle 1A shown in Fig. 2 in the shape of the second space 5C. In the nozzle 1C shown in Fig. 8, the second space 5C is formed longer in the direction Y than in the direction X at the position in the far-near direction where the nozzle 4 is formed. That is, the second space 5C has a length V in the direction X at the position in the far-near direction where the nozzle 4 is formed (distal to the step portion 7). X Length V in direction Y Y If the second space 5C is formed in this way, a flow of the gas-liquid mixture fluid is formed in the second space 5C along the direction Y toward the nozzle 4, and the spray width of the gas-liquid mixture fluid from the nozzle 4 in the direction Y can be widened. In the nozzle 1C, the length V of the second space 5C in the direction Y is Y is the length V in direction X X It is preferably 1.2 times or more, more preferably 1.7 times or more, and is preferably 3.0 times or less, more preferably 2.5 times or less.

[0048] In the nozzle 1C, the distal portion of the second space 5C (specifically, the portion distal to the step 7) is formed so that three cylindrical spaces extending in the near-far direction are lined up in the direction Y and partially overlap one another, and the distal end of the central cylindrical space faces the nozzle 4. In the nozzle 1C, the spray width of the gas-liquid mixture fluid in the direction Y from the nozzle 4 can be changed by changing the shapes of the distal ends of the cylindrical spaces on both sides. The distal ends of the cylindrical spaces on both sides may be formed in an arc shape when viewed in cross section along the near-far direction, as shown in FIG. 8, or may be formed in a flat or tapered shape, etc.

[0049] The nozzle of the present invention can be suitably used for injecting cooling water between rolls in the secondary cooling zone of a continuous casting machine. This will be explained with reference to Fig. 9, which shows a schematic diagram of the secondary cooling zone of a continuous casting facility. Note that the dimensions of the rolls, nozzles, and other components in Fig. 9 may differ from the actual dimensions, as they are shown primarily to facilitate understanding of the present invention.

[0050] In a continuous casting apparatus 11, molten steel in a ladle is poured into a mold 12, cooled within the mold 12 (primary cooling), and then continuously withdrawn downward from the mold 12. A continuously cast slab 13 emerging from the mold 12 is supported by rolls 14 and 15 and withdrawn in the conveying direction, during which water is sprayed from nozzles toward the continuously cast slab 13 to cool it (secondary cooling). In the secondary cooling zone for the continuously cast slab 13, a plurality of rolls 14 are provided facing one main surface 13A of the continuously cast slab 13 along the conveying direction of the continuously cast slab 13, and a plurality of rolls 15 are provided facing the other main surface 13B. The continuously cast slab 13 is conveyed forward sandwiched between the rolls 14 and 15. In this case, it is preferable that the rolls 14 are fixed rolls and the rolls 15 are variable rolls, and the distance between the rolls 14 and 15 is adjustable.

[0051] In the secondary cooling zone of the continuous casting apparatus 11, a nozzle 16 is provided facing one main surface 13A of the continuously cast slab 13, a nozzle 17 is provided facing the other main surface 13B, and a nozzle 18 is provided facing a side surface between the one main surface 13A and the other main surface 13B of the continuously cast slab 13 to cool the continuously cast slab 13. Some or all of the nozzles 16, 17, and 18 may be provided in the secondary cooling zone. The nozzles 16, 17, and 18 are provided facing the continuously cast slab 13 so that the extension direction of the grooves at the tips where the nozzle holes are provided is approximately perpendicular to the transport direction of the continuously cast slab 13. Water is sprayed from the nozzles 16, 17, and 18 toward the continuously cast slab 13, thereby cooling the continuously cast slab 13 within a predetermined range in the width direction or thickness direction.

[0052] The continuous casting apparatus 11 may produce various types of continuously cast strands 13. If the injection flow rate can be changed depending on the conveying speed and steel type of the continuously cast strand 13, and the injection width can be changed depending on the width and thickness of the continuously cast strand 13, this would be preferable, as it would enable appropriate cooling of various types of continuously cast strands 13 in the secondary cooling zone. From this perspective, the nozzle of the present invention is preferably applied to the nozzles 16, 17, and 18. This makes it possible to change the injection flow rate depending on the conveying speed and steel type of the continuously cast strand 13 and to change the injection width depending on the width and thickness of the continuously cast strand 13, without changing the installation position or type of the nozzles 16, 17, and 18, and also makes it possible to cool the continuously cast strand 13 approximately uniformly within a predetermined range in the width or thickness direction.

[0053] The nozzle of the present invention can be applied to some or all of the nozzles 16, 17, 18. When the continuously cast slab 13 is conveyed sandwiched between the fixed roll 14 and the variable roll 15, the nozzle of the present invention is preferably applied to at least the nozzle 17 provided opposite the other main surface 13B of the continuously cast slab 13, or to the nozzle 18 provided opposite the side surface of the continuously cast slab 13. The distance from the nozzle 16 to the one main surface 13A of the continuously cast slab 13 with which the fixed roll 14 contacts does not change depending on the type of continuously cast slab 13, but the distance from the nozzles 17, 18 to the other main surface 13B and side surface of the continuously cast slab 13 with which the variable roll 15 contacts may change depending on the type of continuously cast slab 13. The size of the cross section of the continuously cast slab 13 perpendicular to the conveyance direction varies depending on the steel type. Typically, the narrower the width of the continuously cast slab 13, the greater the distance between the side surface of the continuously cast slab 13 and the nozzle 18. The thinner the thickness of the continuously cast slab 13, the greater the distance between the other main surface 13B of the continuously cast slab 13 and the nozzle 17. In other words, the appropriate injection angle of the nozzles 17, 18, which are provided opposite the other main surface 13B and the side surface of the continuously cast slab 13, varies significantly depending on the steel type. Therefore, it is desirable that the nozzles 17, 18, which are provided opposite the other main surface 13B and the side surface of the continuously cast slab 13, be able to change the injection angle from the nozzles 17, 18 depending on the distance from the continuously cast slab 13, and that the injection amount be able to be changed at the set injection angle. This would enable a single continuous casting facility to optimally cool various types of slabs. The nozzle 16 provided opposite one main surface 13A of the continuously cast slab 13 may be the nozzle of the present invention, or a conventionally known nozzle other than the nozzle of the present invention that is capable of spraying in an approximately fan-shaped manner. However, considering that the width of one main surface 13A of the continuously cast slab 13 may also vary depending on the type of continuously cast slab 13, it is preferable to apply the nozzle of the present invention to the nozzle 16 as well. [Example]

[0054] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following examples, and can be practiced with appropriate modifications within the scope of the above and below-described aims, and all such modifications are included in the technical scope of the present invention.

[0055] (1) Continuous casting method Carbon steel (C: 0.60-1.10%, Si: 0.10-0.90%, Mn: 0.45-1.20%, P: 0.00-0.030%, S: 0.00-0.020%, Cr: 0.00-1.00%, Al: 0.00-0.01%, N: 0.00-0.01%) was continuously cast using the continuous casting apparatus and blooming furnace shown in Figure 10. Two different sizes of cast pieces were produced: 380 mm wide x 339 mm thick and 456 mm wide x 339 mm thick. The casting speed was set in the range of 0.50-0.65 m / min. In the secondary cooling zone, water was injected using the nozzle of the present invention or the comparative nozzle to cool the continuously cast slab, and the amount of secondary cooling water injected was appropriately set so as to keep the specific water amount (i.e., the amount of water injected per unit weight of slab) constant at 0.38 L / kg-steel.

[0056] When performing secondary cooling using the nozzle of the present invention, the gas-liquid ratio was appropriately set to maintain the desired constant injection angle for cooling a 380 mm-wide slab and a 456 mm-wide slab. This ensured that water was sprayed uniformly over the central 6 / 8 region (center) of the slab's width, regardless of the width of the slab. Water was not sprayed significantly over the 1 / 8 and 1 / 8 regions (corners) at either end of the slab's width. A conventional two-fluid nozzle spraying a gas-liquid mixture in a fan-shaped fashion was used as the comparative nozzle. When performing secondary cooling using the comparative nozzle, water was sprayed uniformly over the central 6 / 8 region (center) of the slab's width, while water was not sprayed significantly over the 1 / 8 and 1 / 8 regions (corners) at either end of the slab's width. The 380 mm-wide slab was cooled under the same nozzle injection conditions. Therefore, when a 380 mm wide slab was cooled using the comparative nozzle, an excessive amount of water was sprayed onto the corners, 1 / 8 of the width of one end and 1 / 8 of the width of the slab.

[0057] (2) Evaluation method The number of defects on the surface of each slab continuously cast under each condition and the slab after it was rolled into blooms was counted. The number of defects was counted separately at the center and corners of the slab in the width direction. 2 The number of defects on the surface of the slab was counted after the slab had cooled to room temperature. The fewer the number of defects in the slab and billet, the better the surface quality. For example, if the number of defects in the billet is 30 / m, 2 If the thickness exceeds this value, the amount of work required to repair the defects increases, leading to a decrease in efficiency after blooming.

[0058] (3) Results Table 2 shows the secondary cooling conditions for continuous casting and the evaluation results for the number of surface defects on the slab and billet. Continuous casting tests were conducted under 16 conditions, varying the slab width, nozzle type, and casting speed. The amount of water sprayed from the nozzle was appropriately set to maintain a constant specific water volume. Tests Nos. 1 to 8 show the results of secondary cooling using the nozzle of the present invention, while Tests Nos. 9 to 16 show the results of secondary cooling using the comparative nozzle. Figures 11 and 12 show the measurement results of the nozzle flow rate distribution in the nozzle jet width direction for Tests Nos. 1 to 8. The data for each test number in Table 2 are per charge and represent the average value of the data for each slab and billet within one charge. The slab surface temperature refers to the slab surface temperature at the corner of the inner radius before straightening.

[0059] In Tests Nos. 1 to 8, which used the nozzle of the present invention, the nozzle injection angle during secondary cooling could be appropriately controlled and maintained at a nearly constant injection angle depending on the width of the slab, regardless of the width of the slab, as shown in Figures 11 and 12. Therefore, even under different casting speed conditions, the slab surface temperature before straightening was maintained high. As a result, the slab and billet surface had few cracks or defects in both the center and corners, resulting in good surface quality. In Tests Nos. 9 to 16, which used the comparative nozzle, the number of defects in the corners of the slab and billet was high in Tests Nos. 9 to 12. This is because the comparative nozzle was unable to change the injection angle depending on the slab width. In Tests 13 to 16, water was injected at an appropriate width for the wide slab, whereas in Tests 9 to 12, water was injected over an unnecessarily wide area for the narrow slab. As a result, in Tests 9 to 12, an excessive amount of water was sprayed onto the corners of the slab, which lowered the surface temperature of the slab at the corners before straightening, and this is thought to have caused surface cracks due to the straightening stress.

[0060] [Table 2] [Industrial Applicability]

[0061] The nozzle of the present invention can be suitably used for cooling slabs in the secondary cooling zone of a continuous casting machine, cooling steel plates such as thick plates, thin plates and plated steel plates, cooling steel pipes such as seamless pipes, controlled cooling after rolling and heat treatment, surface treatment of steel plates, cooling of plate materials such as aluminum plates and glass plates, exhaust gas cooling, etc. [Explanation of symbols]

[0062] 1, 1A, 1B, 1C: Nozzle 2: Nozzle body 3: Groove 4: Spout 5: flow path, 5A: first space, 5B: throttle space, 5C: second space 6:Inlet 7:Dan section 8: Orifice member 9: Opening 11: Continuous casting equipment 13: Continuously cast slab, 13A: one main surface, 13B: other main surface 14,15: Roll 16, 17, 18: Nozzle 21: Continuous casting equipment 22: Ladle 23: Tundish 24: Secondary cooling zone 25: Continuously cast slab, 25A: Unstraightened slab 26: Billet cutter 27:Bulking furnace

Claims

1. A two-fluid nozzle for spraying a gas-liquid mixed fluid, a nozzle body having a flow path for a gas-liquid mixture fluid formed therein and extending in a near-far direction; The nozzle body has a groove formed on a distal end surface thereof, and a nozzle hole extending along the extension direction of the groove is provided at a bottom of the groove; the flow path has a first space and a second space located distally of the first space, the nozzle is formed at a distal end of the second space, and a throttle space having a narrow flow path width is provided between the first space and the second space; The throttle space is formed so that the flow path narrows in a stepped manner at the boundary with the first space and at the boundary with the second space, and the flow path width is narrowest at the proximal end of the throttle space and increases from the proximal side to the distal side.

2. The nozzle according to claim 1 , wherein the throttle space is formed in a circular or elliptical shape that is long in the extension direction of the groove when viewed from the distal side or the proximal side.

3. 3. The nozzle according to claim 1, wherein a ratio S1 / S2 of an area S1 of the nozzle hole to an area S2 of the narrowest portion of the throttle space is 0.7 or more and 1.5 or less.

4. The nozzle according to any one of claims 1 to 3, wherein the length of the throttle space in the perspective direction is 2 mm to 10 mm.

5. 5. The nozzle according to claim 1, wherein the outer peripheral surface of the throttle space is formed to be inclined at an angle of 10 degrees or more and 60 degrees or less with respect to the perspective direction.

6. A nozzle as described in any one of claims 1 to 5, wherein the second space is formed such that its length in the direction perpendicular to the extension direction of the groove is longer than its length in the direction perpendicular to the extension direction at the position in the distance direction where the nozzle is formed.

7. The nozzle according to any one of claims 1 to 6, wherein the second space is provided with a step portion in which the width of the flow path narrows in a step-like manner from the proximal side to the distal side.

8. A continuous casting apparatus equipped with the nozzle according to any one of claims 1 to 7, A continuous casting apparatus characterized in that the nozzle is provided facing the continuously cast slab so that the extension direction of the groove is approximately perpendicular to the transport direction of the continuously cast slab.

9. The continuous casting device is provided with a plurality of fixed rolls facing one main surface of the continuously cast slab along a conveying direction of the continuously cast slab, and a plurality of variable rolls facing the other main surface, 9. The continuous casting apparatus according to claim 8, wherein the nozzle is provided facing one or more surfaces selected from the one main surface of the continuously cast slab, the other main surface of the continuously cast slab, and a side surface between the one main surface and the other main surface of the continuously cast slab.

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