JP5459851B2 - Long nozzle - Google Patents

Description

  The present invention relates to a long nozzle that discharges molten steel from a ladle to a tundish.

  When discharging molten steel from the ladle to the tundish during continuous casting of molten steel, it is necessary to use a long nozzle to suppress the oxidation of the molten steel and the slag existing on the upper surface of the tundish being caught in the molten steel. It is common.

The long nozzle is joined to the molten steel discharge nozzle (hereinafter referred to as the lower nozzle) installed at the lower end of the ladle so that the dowel surface is fitted.

The joint portion between the lower nozzle and the long nozzle of the ladle needs to maintain high sealing performance during casting in order to suppress the intrusion of outside air into the long nozzle.

If the sealing performance is lost, the outside air enters the long nozzle or the molten steel, and the quality of the steel is deteriorated due to oxygen in the outside air.

In addition, long nozzles composed of carbon-containing refractories also suffer from oxidation loss of carbon components in the refractory, melting damage due to substances eroding refractories such as FeO generated with molten steel, etc. The durability of the nozzle itself is reduced.

In order to ensure the sealing performance of the joint between the lower nozzle and the long nozzle, for example, in Patent Document 1, as shown in the longitudinal sectional view of the upper end of the long nozzle in FIG. 12, the upper end is passed through a predetermined gap. A structure for supplying an inert gas from a gas inlet 3 through a gap between a metal case to be covered and an upper end of a long nozzle is shown. Patent Document 2 discloses a structure for supplying an inert gas to a nozzle inner hole through a porous brick ring that is an inert gas flow path different from the nozzle upper end gap.

On the other hand, molten steel, molten slag, and the like are scattered and solidified, and fragments such as a refractory sheet installed as a sealing material often adhere to the vicinity of the joint. For this reason, each time the ladle is replaced, the long nozzle is generally disconnected from the lower nozzle, and the vicinity of the joint is removed by oxygen washing or a mechanical impact force such as a bar. Is.

Further, the entire long nozzle inner hole may be filled with molten steel, so-called “blowing” phenomenon, and the molten steel may leak from the joint and solidified steel may adhere to the joint. Such deposits may block the above-described inert gas ejection portion, and thus the sealing performance may be deteriorated.

These occlusion phenomena have not been sufficiently solved by the prior art including the cited reference.

JP 2000-158102 A Japanese Patent Laid-Open No. 9-308950

  It is an object of the present invention to provide a long nozzle even if a gap for blowing out an inert gas provided between a metal case at the upper end and a refractory body of a long nozzle body is blocked, and the ejection of gas from the gap is obstructed. The sealing performance in the vicinity of the joint between the nozzle and the upper nozzle is maintained.

  The long nozzle for discharging molten steel from the container according to the present invention to the tundish has an upper end surrounded by a metal case, and an inert gas is interposed between the metal case at the upper end and the refractory of the long nozzle body. A gap for blowing out the gas, that is, a first gas outlet is provided, and a hole for blowing inactive gas (hereinafter referred to as “second gas jet” is formed on the upper end surface of the metal case at the upper end. The basic configuration is that a plurality of outlets are provided over the entire circumference.

  The upper end of the long nozzle is surrounded by a metal case, and the structure of the first gas jet outlet provided between the metal case and the refractory material of the long nozzle body is the same as that of the prior art. The first gas outlet is close to the junction with the lower nozzle, and also opens in the direction in which the scattered matter that is deposited comes in, that is, (from the center direction of the long nozzle to the radial direction, that is, in the radial direction). Therefore, the deposits are easily fixed and the gas flow is easily blocked.

  In the case of the long nozzle of the present invention, in addition to the first gas ejection port, a hole for ejecting gas, that is, the second gas ejection port, is formed on the upper end surface of the metal case at the upper end. A plurality are installed over the circumference. In the case of the present invention, even if the first gas outlet is closed, the inert gas can be continuously ejected from the second gas outlet, so that the sealing performance of the joint surface between the lower nozzle and the long nozzle is reduced. It becomes possible to suppress.

The main reason why the second gas outlet is difficult to block is as follows.

The joint between the long nozzle and the ladle lower nozzle in the vicinity of the upper end of the inner-bore-side straight body portion is at the vertical position of the long nozzle of the second gas ejection port 5, that is, at a position lower than the upper end surface of the metal case. For this reason, the deposit | attachment which is the object of washing | cleaning (removal) exists in this inner-hole side straight body part vicinity vicinity. When this is cleaned (removed) with an oxygen lance or the like, the adhering matter is melted and scattered. This scattering starts from the upper end of the inner hole and the vicinity of the joint, and further upwards and toward the outer peripheral side of the long nozzle. Therefore, since the scattering direction does not directly hit the second gas ejection port, the second gas ejection port 5 is less likely to be blocked due to the adhering scattered material.

The size, arrangement method, etc. of each of the second gas outlets are determined according to individual operating conditions such as gas flow rate, pressure, etc., long nozzle shape, and specific equipment conditions such as the overall structure of the gas flow path. This should be determined by

The reason for this is that the flow state of the gas varies depending on many factors such as the structure of the flow path, the length, the vicinity of the jet outlet and the shape of the cross section, the pressure, and so on. This is because it is necessary to determine an optimal arrangement so as to match. That is, it is preferable that gas is ejected in a state as close as possible on the circumferential direction of the upper end surface of the long nozzle, and the size and arrangement method of each of the second gas ejection ports are designed as such. It is.

Therefore, specifically, the second gas outlets can be arranged uniformly over the entire upper end surface of the metal case, and the sizes of the respective second gas outlets can be made uniform.

Generally, the gas inlet is installed at one location on the long nozzle cross section, and the gas passes through the space as the flow path, that is, the gas pool, on the long nozzle cross section, and the direction of the counter electrode. To distribute.

The cross-sectional area of the gas path is not so large as to cause no pressure loss. Normally, the pressure loss and the gas ejection amount gradually decrease from the gas introduction side to the counter electrode side. Even in such a case, in order to make the gas ejection at the upper end surface of the metal case more uniform throughout, the size and arrangement method of each of the second gas ejection ports are changed and arranged. can do.

Specifically, when the upper end surface of the metal case is divided into two in the center, the region on the gas inlet side and the region on the anti-gas inlet side, the number of second gas outlets is the region on the gas inlet side. It arrange | positions so that it may increase more in the area | region on the anti-gas inlet side.

  As the number of the second gas ejection ports 5 increases, the gas becomes easier to be ejected. Therefore, although the gas pressure gradually decreases from the gas introduction port side to the counter electrode side, the gas ejection amount is equalized. .

  In such a configuration, during operation, the second gas outlet is unlikely to be blocked, and the operation due to the blockage of the gas outlet is not hindered. The reason is as follows.

The joint (see FIG. 11 described later) between the long nozzle and the ladle lower nozzle in the vicinity of the upper end of the inner cylinder side straight barrel portion is located at the vertical position of the long nozzle of the second gas jetting port 5, that is, on the metal case. It is in a position below the end face.

The deposit that is the object of cleaning (removal) is present near the upper end of the inner-hole-side straight body. When this is cleaned (removed) with an oxygen lance or the like, the adhering matter is melted and scattered. This scattering starts from the upper end of the inner hole and the vicinity of the joint, and further upwards and toward the outer peripheral side of the long nozzle. Therefore, since the scattering direction does not hit the second gas jet port directly, the second gas jet port is less likely to be blocked by the adhering of scattered matter.

In addition, the scattering direction in the case where scattering due to leaked steel or the like from the joint occurs is the same as described above, and the second gas jetting port 5 is less likely to be blocked by the adhesion of such scattered matter.

  The size and number of the second gas outlets 5 are determined from the required amount of gas and the like according to the conditions in individual operations.

  In the long nozzle of the present invention, a wall can be provided on the center direction side of the long nozzle of the plurality of holes serving as the second gas ejection ports. This wall serves as a barrier so that even if adhering material such as molten steel, molten slag, or molten FeO scatters from the vicinity of the joint surface between the lower nozzle and the long nozzle, the second gas injection port is not immediately blocked. Fulfills the function.

The length of the wall in the circumferential direction is preferably equal to or greater than the width of the hole in the circumferential direction of the long nozzle. That is, if the long steel passing direction of the long nozzle is the longitudinal direction, the scattered matter will fly from the vicinity of the center in the horizontal direction, which is a direction substantially perpendicular to that direction, to the second gas ejection port direction. If there is a wall with a width equal to or greater than the circumferential length in the outlet direction, the second gas jet outlet is not directly blocked.

Moreover, it is preferable that the height of this wall is more than the length of the 2nd gas ejection port of the 2nd gas ejection port in the radial direction of a long nozzle. That is, most of the scattered matter is scattered from below the longitudinal position of the long nozzle of the second gas outlet toward the second gas outlet, but this scattering state is not constant, and the upper end surface of the metal case Although it is almost from the lower side, it may be scattered in the direction from the upper end surface of the metal case to about 30 degrees upward in the direction of the second gas ejection port.

In this case, the height of the wall installed on the center direction side of the long nozzle of the plurality of holes serving as the second gas ejection port is not less than the circumferential length in the direction of the second gas ejection port. That is, since the angle formed by the line connecting the outermost peripheral position of the long nozzle of the second gas outlet and the upper end of the wall is 45 degrees or more, the scattered matter from at least the range from the horizontal position to 45 degrees is directly The second gas outlet is not blocked.

  According to the present invention, even if the gap for blowing out the inert gas provided between the metal case at the upper end of the long nozzle and the refractory of the long nozzle body is blocked and the gas ejection is obstructed from the gap, the long nozzle and its It is possible to suppress or maintain a decrease in the sealing performance in the vicinity of the joint with the upper nozzle.

As a result, the local damage of the long nozzle and the lower nozzle can be suppressed, it can contribute to stable and safe operation, and the effect of lowering the quality of steel can also be suppressed.

It is the longitudinal cross-sectional view and top view of the upper part of the long nozzle which concern on the Example of this invention. It is a top view which shows arrangement | positioning of the 2nd gas jet nozzle which concerns on this invention. It is a figure which shows the distribution state of the ejection gas from the 2nd gas ejection port in a 1st case. It is a figure which shows the distribution state of the ejection gas from the 2nd gas ejection port in a 2nd case. It is a comparison figure which shows the local erosion rate of an inner hole. It is a top view which shows the part which provided the wall adjacent to the 2nd gas jet nozzle as a part. It is an enlarged view of the part a of FIG. FIG. 8 is a longitudinal sectional view of FIG. 7. The relative relationship of the 2nd gas jet nozzle in FIG. 8 and the vertical direction of a wall is shown. The joining example of a long nozzle and a ladle lower part nozzle is shown with a longitudinal cross-sectional view. It is an image figure which shows the target of the washing | cleaning (removal) adhering to the inner-hole upper end and joining part vicinity of a long nozzle, and the scattering direction at the time of the washing | cleaning. The longitudinal direction sectional drawing and top view of the upper part of the conventional long nozzle are shown.

  Hereinafter, embodiments of the present invention will be described based on examples.

Example 1
FIG. 1 is a longitudinal sectional view and a plan view of an upper portion of a long nozzle according to the present invention. In the figure, the upper end is surrounded by a metal case 1, and a gap for blowing out an inert gas from the gas inlet 3 between the refractories 2 of the long nozzle body, that is, the first gas. A spout 4 is provided. This structure itself is a conventional structure. In the case of the present invention, in addition to the first gas outlet 4, a hole for blowing out an inert gas, that is, a second gas outlet 5 is provided on the upper end surface of the metal case 1. A plurality of two gas outlets 5 are provided over the entire circumference.

FIG. 2 shows that when the upper end surface of the metal case 1 is divided into two at the center, the region A on the gas inlet 4 side and the region B on the anti-gas inlet side, the number of the second gas outlets 5 is A and B. The case of (a) arranged 32 equally in the region and the case of (b) installed more in the region B on the side opposite to the gas introduction port than the region A on the gas introduction port side are shown. In the case of (b), 23 of the second gas ejection ports 5 are 2 at the boundary, 8 in the 1/2 region on the gas inlet side, and a 1/2 region on the anti-gas inlet side. 13 are arranged.

  3 and 4, the second gas outlet 5 has the same circular shape with a diameter of 3 mm, a gauge pressure of 0.1 MPa, and a total flow rate of 80 Nl / min. The result of investigating the gas ejection distribution at the gas inlet side end, the anti-gas inlet side end, and the center at two places in total, using the above air, is shown.

FIG. 3 shows the case (a), and FIG. 4 shows the case (b). In the case of (a) shown in FIG. 3, the flow rate is higher in the portion closer to the gas introduction portion than in the other portions, and the distribution is uneven on the upper end surface of the long nozzle. On the other hand, in the case of (b) shown in FIG. 4, the ejection distribution is almost uniform throughout. From the investigation of the jet distribution of both, it became clear that the gas jet quantity was equalized by relatively increasing the gas jet quantity on the anti-gas inlet side than on the gas inlet side. From this result, although the effect of gas ejection itself can be obtained, it is possible to install a larger number of second gas ejection ports in the B region on the side opposite to the gas introduction port than in the A region on the gas introduction port side. It can be seen that gas ejection can be equalized and preferable compared to the case where the second gas ejection ports are arranged uniformly on the entire circumference.

  The long nozzle of the present invention in which the second gas jet port was installed by the arrangement method according to the case of FIG. 2B was used for actual operation together with a comparative example in which the second gas jet port was not installed. In this operation test, Ar gas was used, and the gas pressure (original pressure, gauge pressure) was approximately 0.1 MPa gauge pressure and a total flow rate of 80 Nl / min. Met.

The result of this actual operation is shown in FIG. The number of ladle exchanges (number of charges) was 23-36. As a result, the degree of melting loss generated in the long nozzle inner hole in the vicinity of the joint between the long nozzle and the lower nozzle, that is, the degree of damage due to the intrusion of outside air from the joint (average value) is 0 in the comparative example. .023 mm / min. In contrast, in the examples, 0.016 mm / min. And a significant improvement was confirmed.

Further, the variation in the degree of damage (minimum to maximum value) is 0.007 to 0.074 mm / min. On the other hand, in the examples, 0.010 to 0.019 mm / min. And became much smaller.

Example 2
In the second embodiment, the jet port of the second gas jet port 5 provided together with the first gas jet port 4 provided between the refractories of the long nozzle body of the metal case 1 shown in FIG. In addition to the state of being installed in the directly upward direction, as shown in FIG. 6, the wall 6 adjacent to the center direction side of the long nozzle of the second gas outlet, that is, the scattered matter is directly injected into the second gas jet. The example which provided the barrier for preventing closing an exit is shown.

  As shown in FIG. 6, a wall 6 can be installed on the center side adjacent to the second gas outlet 5. In this case, the wall 6 is most preferably integrated with the metal case from the viewpoint of the strength of the wall and ease of manufacturing.

7 is an enlarged view of the portion a in FIG. 6, and FIG. 8 is a longitudinal sectional view of FIG. 7, and shows the positional relationship of the wall 6 with respect to the second gas outlet 5. As shown in these figures, the length Lw of the wall 6 may be intermittently installed with a length equal to or larger than the diameter LH of the second gas jetting port 5. It is good also as a continuous integral structure. Further, if the thickness of the wall 6 is equal to that of the metal case 1, the function can be easily maintained without causing deformation or the like.

Further, FIG. 9 is a diagram showing the relative relationship in the vertical direction between the wall 6 and the second gas ejection port 5 at an angle θ. As described above, when the wall 6 is provided adjacent to the second gas ejection port, since the scattered matter comes from the inner hole side of the long nozzle, it travels straight from at least the direction within the range of θ degrees shown in the figure. The flying flying object does not hit the second gas jetting port 5 and block it. For this reason, there is an effect of further preventing the scattered matter from directly blocking the second gas ejection port 5.

  That is, in FIG. 10 which shows the joining example of the long nozzle 10 and the ladle lower nozzle 11 by a longitudinal cross-sectional view, the joining part 12 with the upper nozzle 11 installed on the refractory 2 at the tip part of the long nozzle is The longitudinal position of the long nozzle of the second gas outlet 5, that is, the position below the upper end surface of the metal case 1.

Therefore, as shown by the scattering direction X of the scattered object that is the cleaning object attached to the upper end of the inner hole of the long nozzle in FIG. 11 and the vicinity of the bonded part, most of the scattered object starting from this bonded part is the second It will be scattered in the direction of the gas ejection port, and it will be less likely that the second gas ejection port 5 will be blocked due to the adhering matter.

Furthermore, in FIG. 9, since the angle θ from the upper end surface of the metal case 1 to approximately 30 degrees may be scattered in the direction of the second gas outlet 5, the second gas outlet 5 In the relative relationship between the length in the radial direction and the height of the wall 6, the wall 6 is installed so that the angle θ is about 30 degrees or more, so that at least the region within the θ is from the center of the long nozzle. The scattered matter does not collide with the wall 6 and block the second gas ejection port 5.

The height of the wall 6 may be determined so as not to interfere with each other due to the relationship between the upper end surface of the long nozzle and the equipment existing thereabove, but the wall 6 should be installed so that the angle θ is about 45 degrees. Is most preferred.

The angle θ is mainly derived from the position of the deposit near the upper end of the metal case, the inclination of the long nozzle, the flow of the melt, and the like in the oxygen cleaning and deposit removal operation near the upper end of the long nozzle. Therefore, it may be determined according to each operating condition. However, since there is generally no flying base point or inclination exceeding 45 degrees at the maximum, the maximum of the angle θ is most preferably about 45 degrees. .

  Note that, as described above, it is possible to determine that it is not necessary to install the entire wall in general because there is a sufficient effect without installing the wall adjacent to the second gas ejection port. In other words, the installation of this wall may be applied in the case of operating conditions in which scattering to the upper end surface of the long nozzle is severe and there is a possibility of closing the second gas ejection port.

1 Metal case 2 Refractory body of long nozzle body 3 Gas inlet
4 First gas ejection port 5 Second gas ejection port 6 Wall 10 Long nozzle 11 Upper nozzle 12 Joint portion of long nozzle and upper nozzle

Claims (3)

  The upper end is surrounded by a metal case, and a first gas outlet for blowing out inert gas is provided between the metal case at the upper end and the refractory material of the long nozzle body, and the upper end surface of the metal case The long nozzle is provided with a plurality of second gas outlets. When the upper end surface of the metal case is divided into two in the center, the region on the gas inlet side and the region on the anti-gas inlet side, the number of the second gas outlets is more negative than the region on the gas inlet side. The long nozzle according to claim 1, wherein the long nozzle is provided in a large area on the gas inlet side. A circumferential length equal to or larger than the width of the hole in the circumferential direction of the long nozzle adjacent to the central direction side of the long nozzle of the plurality of second gas outlets installed on the upper end surface of the metal case. The long nozzle according to any one of claims 1 and 2, further comprising a wall having a height that is equal to or greater than a length of the second gas outlet in the radial direction of the long nozzle.