JP5781385B2 - Degassing equipment dip tube - Google Patents

Description

The present invention relates to a dip tube of a degassing apparatus used in a melting step of an iron making process.

The molten steel that has undergone primary refining in the converter is degassed using a vacuum degassing facility (hereinafter also simply referred to as degassing facility) for the purpose of decarburization and removal of dissolved gases such as hydrogen and nitrogen. Is done. Examples of the degassing method include a DH (Dortmount-Horde) method and a RH (Ruhrstahl-Heraus) method.
The degassing equipment used for this degassing process has a vacuum degassing tank and a dip tube provided in the lower part thereof. In addition, the dip tube generally has a configuration in which refractories are provided on the inner peripheral side and the outer peripheral side of the cylindrical metal core, and the degassing treatment is performed by taking the tip (lower end) of the dip tube into the ladle. The molten steel is immersed in the molten steel, and the molten steel is sucked into a vacuum degassing tank and simultaneously refluxed.

However, as described above, the degassing treatment is performed in a state where the tip of the dip tube is immersed in the molten steel in the ladle, so that the refractory at the tip (immersed part) is damaged, In addition, since the core metal is deformed by heat, the life of the dip tube cannot be extended.
Thus, for example, Patent Document 1 discloses a dip tube in which a heat insulating mortar is disposed between a cylindrical cored bar (core tube) and a refractory (refractory material).
Further, in Patent Document 2, a purge pipe that serves as a feed path for an inert gas used to suppress the intrusion of air into the refractory is provided on the outer peripheral surface of the metal core (on the outer peripheral side of the metal core). A dip tube disposed in the refractory) is disclosed.

JP 2010-168600 A JP 2010-106294 A

However, the conventional dip tube still has the following problems to be solved.
The dip tube described in Patent Document 1 contracts when the heat-insulating mortar is sintered due to heat received during operation. For this reason, when the thickness of the heat insulating mortar is increased in order to improve the heat insulating effect, a gap generated on the back side of the wear refractory due to the shrinkage allowance of the heat insulating mortar becomes large. It becomes unstable, causing problems such as opening of brick joints and cracking of irregular shaped refractories (castable, etc.), and in extreme cases, wear refractories may fall off.
In addition, since the dip tube is operated at a high temperature, it is considered that the heat insulation mortar shrinks and the thermal conductivity is significantly increased. In particular, with the increase in the number of times of use (treatment) of the dip tube, it is conceivable that the decrease in the heat insulation property becomes significant when the sintering (sintering) of the heat insulating mortar proceeds and the structure becomes dense.
In this case, thermal deformation (expansion) occurs in the metal core exposed to high temperature, joint opening occurs in the brick that cannot follow the deformation, and cracks occur in the amorphous refractory, which are immersed in the dip tube. There is a risk that the life of the dip tube will be limited and the life of the dip tube cannot be extended.

In addition, the dip pipe described in Patent Document 2 uses a cooling effect by an inert gas by circulating a part of the purge pipe (circumferential pipe) along the outer peripheral surface of the lower end portion of the core metal, The lower part of the metal core is cooled.
However, the heat input from the molten steel to the dip tube is large, and with the above-described configuration, the cooling capacity of the core metal becomes insufficient, and the effect of suppressing the deformation of the core metal may be insufficient. The purge piping is used to suppress the intrusion of air into the refractory, and is buried in the refractory on the outer peripheral surface side of the metal core, so that the flow of Ar gas flowing out from the purge piping is It is difficult to control the path, and it is difficult to effectively cool the metal core at the target location.

The present invention has been made in view of such circumstances, soaking of a degassing apparatus capable of suppressing the deformation of the metal core and the damage of the refractory covering the metal core, and stably extending the life until the end of the life. The purpose is to provide a tube.

The dip tube of the degassing apparatus according to the present invention in accordance with the above object is a degassing apparatus immersing the inner peripheral refractory and the outer peripheral refractory on the inner peripheral side and outer peripheral side of the cylindrical cored bar, respectively. In the tube
A heat insulating material having a thickness of 1 mm or more and 5 mm or less is disposed between one or both of the inner peripheral refractory and the metal core and between the outer peripheral refractory and the metal core, A supply header for blowing Ar gas toward the heat insulating material is provided.

In dip tube degassing apparatus according to the present invention, the thermal insulator preferably has a thermal conductivity at ambient temperature of 500 ° C. is 0.05W / (m · K) or less.

In the dip tube of the degassing apparatus according to the present invention, since a heat insulating material is disposed between the core metal (particularly, air-cooled core metal) and the refractory, the thickness direction of the refractory, that is, the working surface (molten steel contact surface side). It is possible to make the temperature gradient between the refractory and the back surface (insulating material side) gentle, and to reduce the rapid temperature change of the refractory (rapid cooling due to heat removal). Thereby, since the spalling damage (peeling damage) of the refractory can be reduced, the life of the refractory can be improved.
Also, even if the core metal of the dip tube is air-cooled, since the dip tube is used by immersing it in the molten steel being processed, the heat input from the molten steel is large and the temperature of the core metal becomes high, The thermal expansion of the core metal causes the joint opening of the brick and the cracking of the irregular refractory. For this reason, the ingot enters into the refractory through the open joints and cracks, leading to a further increase in the core metal temperature, and damage that determines the life of the dip tube, resulting in a short life of the dip tube. Therefore, by disposing a heat insulating material between the core metal and the refractory, deformation of the core metal is suppressed, and the life of the refractory can be extended.
Furthermore, since the working surface of the heat insulating material provided on the dip tube (surface on the molten steel contact surface side) becomes extremely hot, the heat insulating material shrinks at the end of the life of the dip tube and the heat insulating property of the heat insulating material. In addition, joint opening and cracking of the refractory are caused by the gap between the refractory and the heat insulating material generated by this shrinkage. Therefore, in order to suppress these, a supply header that blows Ar gas toward the heat insulating material is provided. As a result, shrinkage of the heat insulating material can be reduced, and the generated gap can be used as an Ar gas flow path so that the Ar gas can actively cool the heat insulating material and the metal core even after the heat insulating function of the heat insulating material is deteriorated. .
From the above, the dip tube of the degassing apparatus of the present invention can stably extend the life until the end of its life.

Moreover, when the heat conductivity in the atmospheric temperature of 500 degreeC of a heat insulating material is 0.05 W / (m * K) or less, the spalling damage of a refractory can be further suppressed and the further improvement of a refractory life can be aimed at. This is because the heat input from the molten steel is avoided by heat insulation and the core metal temperature of the dip tube can be reduced as the thermal conductivity of the heat insulating material is lowered.

And, since the thickness of the heat insulating material is 1mm or 5mm or less, it is possible to maintain the heat insulating property of the heat insulating material, the cracking of the joint opening and monolithic refractory brick due to shrinkage of the insulation material can be prevented. Accordingly, the service life of the second half of the operation of the dip tube can be further extended, and sudden troubles due to, for example, sudden peeling of the refractory can be avoided.

It is a partial front sectional view of a dip tube of a degassing apparatus according to an embodiment of the present invention. (A)-(D) are the partial expansion front sectional views of the supply header of the dip tube of the degassing apparatus which concerns on the 1st-4th modification, respectively.

Next, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.
As shown in FIG. 1, a dip tube (hereinafter also simply referred to as a dip tube) 10 of a degassing apparatus according to an embodiment of the present invention is a wear refractory on the inner peripheral side of a cylindrical cored bar 11. A certain brick (an example of the inner refractory) 12 is provided, and an irregular refractory (an example of the outer refractory) 13 that is a wear refractory is provided on the outer periphery, respectively, until the end of life. Long life can be achieved stably. This will be described in detail below.

The dip tube 10 can be used for the purpose of decarburization and degassing of molten steel using vacuum (reduced pressure). The dip tube is not particularly limited as long as it is used for the above-described decarburization and degassing refining. For example, the DH method, the RH method, and further CAS (Composition Adjustment by Sealed Argon Bubbling). It may be used for law.

The cored bar 11 of the dip tube 10 has a cylindrical shape made of iron (metal), and its upper end is connected to a vacuum degassing tank (not shown). A support metal 14 for supporting the bricks 12 arranged on is fixed. The cored bar 11 is cylindrical here, but is not particularly limited as long as it is cylindrical.
Further, the cored bar 11 has a structure having a hollow portion 15 whose inside is shielded from the outside air, and has a configuration capable of cooling the cored bar 11 from the inside (a configuration capable of air cooling), depending on use conditions. For example, it can also be set as the structure (solid plate shape) which does not have a hollow part.

As described above, the brick (brick) 12 is installed on the inner peripheral side of the core metal 11, but an irregular refractory can also be installed according to the use application of the dip tube. Further, as described above, the amorphous refractory 13 is mainly used on the outer peripheral side of the core metal 11 as described above. However, the amorphous refractory and brick may be used in combination.
A conventionally known refractory material can be used for the brick 12 and the indeterminate refractory 13 covering the cored bar 11. Examples of the refractory material include magnesia-chromium, magnesia-carbon, alumina-chromium, alumina-carbon, alumina-magnesia, alumina-magnesia-carbon, alumina-spinel-carbon, and the like.

Between the radial inner surface of the core metal 11 and the radial outer surface of the brick 12, and between the radial outer surface of the core metal 11 and the radial inner surface of the amorphous refractory 13, a heat insulating material 16 is provided. Is arranged. Thereby, in the first half of operation of the dip tube 10, it becomes possible to suppress the deformation | transformation of the metal core 11 with a heat | fever by the heat insulation effect of the heat insulating material 16, and it can contribute to the lifetime extension of the brick 12 and the amorphous refractory 13.
The heat insulating material 16 is disposed directly on the inner surface and the outer surface of the core metal 11, but the heat insulating material 16 is disposed between the core metal 11 and the brick 12 and between the core metal 11 and the amorphous refractory 13. If it is arranged, it is not limited to this. For example, if the heat insulating material 16 is disposed adjacent to the metal core 11 (arranged at a position where the heat insulating function can be exhibited), the heat insulating material 16 is fixed (adhered) to the surface of the metal core 11. A refractory material (adhesive material) such as a thin mortar can be installed between the materials 16.

In addition, as described above, when installing an irregular refractory on the core metal, in order to support the irregular refractory, for example, a stud is often installed on the outer periphery of the core metal. The stud is installed avoiding the above-mentioned heat insulating material.
Moreover, although the heat insulating material 16 is installed in both the inner peripheral side and outer peripheral side of the metal core 11, even when arrange | positioning only in any one of an inner peripheral side and an outer peripheral side, the deformation | transformation of the metal core 11 by heat | fever Can be suppressed to some extent, and can contribute to extending the life of the brick 12 or the irregular refractory 13. However, as described above, it is more desirable to arrange the heat insulating material 16 on both the inner peripheral side and the outer peripheral side of the core metal 11.

As this heat insulating material, for example, an inorganic fibrous heat insulating material such as ceramic fiber, an inorganic indefinite heat insulating material (refractory material) for performing pouring construction or glazing construction, a microporous heat insulating material, or the like may be used. it can.
In order to further enhance the heat insulating effect of the heat insulating material, it is preferable to use a heat insulating material having a thermal conductivity of 0.05 W / (m · K) or less at an atmospheric temperature of 500 ° C. For example, the thermal conductivity at an ambient temperature of 500 ° C. is about 0.1 W / (m · K) for a ceramic fiber, and 0.05 W / (m · K) or less for a microporous heat insulating material having a cell structure. However, the above-described microporous heat insulating material has lower thermal conductivity.

Here, the reason why the thermal conductivity of the heat insulating material is defined at an ambient temperature of 500 ° C. is that the use environment of the dip tube in which the heat insulating material is installed is taken into consideration. The reason why the thermal conductivity is specified to be 0.05 W / (m · K) or less is that heat input from the molten steel must be avoided by heat insulation, and the core metal temperature of the dip tube must be reduced. This is because it is desirable to be conductive.
Therefore, although a heat insulating material having a thermal conductivity of 0.05 W / (m · K) or less at an atmospheric temperature of 500 ° C. was used, the thermal conductivity was 0.04 W / (m · K) or less, and further 0.035 W. It is preferable to use a heat insulating material of / (m · K) or less.
On the other hand, for the reasons described above, the lower limit value of the thermal conductivity of the heat insulating material is not stipulated, but considering the low heat conductive heat insulating material existing in the world, for example, 0.01 W / (m · K) It is.

Moreover, it is preferable that the thickness of a heat insulating material shall be 1 mm or more and 5 mm or less.
The reason why the lower limit of the thickness of the heat insulating material is set to 1 mm is that the ceramic fiber and the microporous heat insulating material take into consideration the thickness that can be manufactured while maintaining the heat insulating property. On the other hand, the reason why the upper limit value of the thickness is set to 5 mm is that consideration is given to the thickness at which the joints of the bricks (joint breaks) and cracks of the irregular refractory do not occur due to the shrinkage of the heat insulating material.
Therefore, by setting the thickness of the heat insulating material to 1 mm or more and 5 mm or less, it is possible to further extend the life of the dip tube in the second half of the operation (after the deterioration of the performance of the heat insulating material) and to avoid sudden troubles due to sudden refractory peeling. However, it is preferable that the lower limit is 1.5 mm, more preferably 2 mm, and the upper limit is 4 mm, further 3 mm.

Further, supply headers 17 and 18 are provided between the brick 12 and the heat insulating material 16 and between the amorphous refractory 13 and the heat insulating material 16, respectively.
One supply header 17 is annular and extends along the surface of the heat insulating material 16 on the inner peripheral side through a support portion (not shown) protruding radially inward from the inner peripheral surface of the cored bar 11. , Fixed to the cored bar 11. Further, the other supply header 18 is also formed in an annular shape so as to be along the surface of the heat insulating material 16 on the outer peripheral side through a support portion (not shown) protruding radially outward from the outer peripheral surface of the cored bar 11. , Fixed to the cored bar 11. In addition, each supply header may contact the inner peripheral surface and outer peripheral surface of the cored bar 11, respectively. Moreover, the diameter of the piping which comprises each supply header 17 and 18 is about 10 mm or less, for example.

A large number of ejection holes 19 are formed in each supply header 17, 18 at an equal pitch in the circumferential direction of the core metal 11. Each of the ejection holes 19 has an opening portion located between the brick 12 and the heat insulating material 16 (near the interface) and between the amorphous refractory 13 and the heat insulating material 16 (near the interface), It is formed in each supply header 17, 18.
Thereby, the cooling Ar (argon) gas supplied from the outside of the dip tube 10 is supplied to the supply headers 17 and 18 via the gas supply pipes 20 and 21, respectively, and thus from each of the ejection holes 19. It can be sprayed toward the heat insulating material 16.
In addition, the arrangement | positioning position of a supply header and the formation position of an ejection hole are not limited to an above-described position, What is necessary is just a position which can spray Ar gas toward a heat insulating material.

For example, as shown in FIG. 2A, a supply header 22 formed so that the ejection holes 19 are located inside the heat insulating material 16 is installed between the amorphous refractory 13 and the heat insulating material 16. Thereby, Ar gas can be sprayed inside the heat insulating material 16.
Further, as shown in FIG. 2B, a supply header 23 formed so that a plurality of ejection holes 19 are located inside the heat insulating material 16 and between the amorphous refractory 13 and the heat insulating material 16 is provided. It is installed between the irregular refractory 13 and the heat insulating material 16. Thereby, Ar gas can be sprayed to the inside of the heat insulating material 16 and the surface of the heat insulating material 16, respectively.

Then, as shown in FIG. 2C, the supply header 24 formed so that the ejection hole 19 is positioned between the amorphous refractory 13 and the heat insulating material 16 is installed in the amorphous refractory 13. . Thereby, Ar gas can be sprayed on the surface of the heat insulating material 16.
Further, as shown in FIG. 2D, a supply header 25 formed so that the ejection hole 19 is located in the irregular refractory 13 and faces the surface of the heat insulating material 16 is provided in the irregular refractory 13. Install in. Here, the Ar gas blown from the blowout holes 19 can be blown onto the surface of the heat insulating material 16 through the pores in the amorphous refractory 13.

The supply header 25 shown in FIG. 2D is installed within a range in which Ar gas can be sprayed onto the heat insulating material 16 even when the ejection hole 19 is positioned in the amorphous refractory 13. Specifically, the shortest distance (distance in the radial direction) d from the surface of the heat insulating material 16 (the contact surface with the amorphous refractory 13) to the ejection hole 19 is, for example, about 5 mm or less. Here, even if the amorphous refractory in front of the ejection hole 19 of the supply header 25 (gas blowing direction) is removed and Ar gas is directly sprayed on the heat insulating material 16 without passing through the pores in the amorphous refractory. Good.
The flow rate of Ar gas blown out from the outlet hole of the supply header shown above can be adjusted, for example, to about 10 to 200 (Nm ³ / hour).

Of course, the installation position of the supply header and the formation position of the ejection holes can also be applied to the supply header on the brick side. It should be noted that the supply header is not installed on both the inner and outer peripheral sides of the cored bar, but is arranged only on either the inner or outer peripheral side in correspondence with the installation position of the heat insulating material. Also good.
And although a supply header is attached and fixed to the metal core, it is not limited to this, For example, it can also wind and fix to the surface of a heat insulating material.

The installation height position of the supply header is not particularly limited as long as it is the front side (lower side) of the dip tube, but considering the portion where the core metal is likely to be thermally deformed, the tip of the dip tube The part (lower end part) is preferable.
Furthermore, the Ar gas blown from the supply header to the heat insulating material can be diverted from the “purging Ar” used for preventing the outside air from entering the dip tube of the degassing apparatus that is generally used. . In this case, by directing the Ar gas blowing position in the refractory to the surface of the heat insulating material using a flow path such as a pipe, both the prevention of outside air intrusion by the “purging Ar” and the suppression of the deterioration of the heat insulating property can be achieved. It becomes possible. Here, the above-described flow path becomes a supply header for blowing Ar gas.

Then, the degassing method using the dip tube 10 of the degassing apparatus which concerns on one embodiment of this invention is demonstrated.
First, as shown in FIG. 1, a heat insulating material 16 is disposed between the core metal 11, the brick 12 and the amorphous refractory 13, and supply headers 17 and 18 for blowing Ar gas toward the heat insulating material 16 are provided. A dip tube 10 is prepared. And the front-end | tip part of this dip tube 10 is immersed in the molten steel in a ladle (not shown), and a degassing process is performed.

In general, the life of a refractory is determined by the remaining state of the refractory due to the wear of the refractory due to wear or melting caused by molten steel or slag. However, other than that, the life of refractories used in the dip tube of the degassing device is greatly affected by cracks and delamination caused by thermal deformation of the core metal of the dip tube, resulting in cracks and joint openings. Therefore, there is a rate-determining factor other than the remaining thickness of the refractory.

That is, at the initial stage of operation of the dip tube, thermal deformation of the cored bar of the dip tube is prevented due to the effect of heat insulation. Therefore, the size of the heat insulation is a factor that suppresses deformation of the cored bar and further determines the life of the dip tube. .
Also, in the second half of the operation of the dip tube, the heat insulating property of the heat insulating material decreases due to shrinkage due to heat reception, and conversely, cracks due to the size of the void due to the shrinkage of the heat insulating material occur, so the shrinkage allowance of the heat insulating material is It is a factor that determines the life of the dip tube.

Then, like the above-mentioned dip tube 10, the heat insulating material 16 is arrange | positioned between the metal core 11, the brick 12, and the irregular-shaped refractory 13, and the heat insulation of the heat insulating material 16 is carried out in the first half operation of a dip tube. It can be maintained, deformation of the cored bar can be suppressed, and the life of the refractory can be extended.
Furthermore, since the dip tube 10 has supply headers 17 and 18 for blowing Ar gas toward the heat insulating material 16, it is possible to reduce the shrinkage of the heat insulating material 16 in the latter half of the operation of the dip tube. By flowing Ar gas through the generated gap, the heat insulating material 16 and the core metal 11 can be actively cooled.

Ar gas should flow in the latter half of the operation of the dip tube, for example, according to the progress of the deterioration of the heat insulating function of the heat insulating material obtained from past empirical rules. However, it is preferable to divert the above-mentioned “purge Ar” pipe, which is normally used, so that the Ar gas can flow continuously from the beginning to the end of the operation of the dip tube, thereby opening joints, generating cracks, etc. It is possible to extend the service life stably.
Therefore, by using the dip tube of the degassing apparatus of the present invention, deformation of the core metal and damage to the refractory covering the core metal can be suppressed, and the lifetime can be stably extended until the end of the lifetime.

Next, examples carried out for confirming the effects of the present invention will be described.
Here, the dip tube of the degassing apparatus of DH method was used. Note that magnesia-chromic bricks were used for the ware refractories on the inner periphery side of the dip tube, and alumina-magnesia amorphous refractories were used for the refractories on the outer periphery side.
Table 1 shows the presence / absence of the supply header to the dip tube, the type of heat insulating material used for the dip tube, the thermal conductivity, the thickness, and the refractory damage under each condition.

With regard to the presence or absence of the supply header shown in Table 1, 100% (Nm ³ / hour) of purge Ar gas was constantly flowed through the supply header during the degassing process and sprayed onto the heat insulating material.
In addition, “CF” in the type of heat insulating material means ceramic fiber. Further, “WDS” is “Poretherm WDS (registered trademark)” manufactured by Porextherm Damstoff Gmbh, and the material thereof is a microporous molded body mainly composed of fumed silica.

The average wear rate of the brick is the amount of wear per charge of the brick installed on the inner peripheral side of the core metal of the dip tube. This average wear rate is determined by the amount of indented refractory that was pressed into the inner periphery of the core during the first repair of the brick installed on the inner periphery of the core (after 80 to 100 charges from the start of operation). By measuring, the amount of wear of the brick was obtained and calculated from the result. Specifically, a cylindrical core with a constant inner diameter is set in the dip tube (degassing tank), and the gap between the core and the brick is closed between the core and the lower end of the dip tube. Then, an irregular refractory was press-fitted to the height of the dip tube, and the repair thickness was determined from the height of the dip tube and the measured amount (volume) of the irregular refractory.

Furthermore, the evaluation was performed by comprehensive evaluation including both the effect of suppressing wear and defects at the end of operation.
In addition, the effect of wear suppression is an evaluation showing the durability of the brick, and is a result obtained from the average wear rate of the brick. Here, the average wear rate is 1.0 (mm / ch) or less as “」 ”, 1.0 (mm / ch) and 1.5 (mm / ch) or less as“ ◯ ”, 1.5 (mm / ch). ch) “×” was defined as “super”.
Further, the defect at the end of operation was an evaluation showing the stability of operation (whether or not a sudden trouble occurred), and the presence or absence of joint opening or crack generation was visually monitored.

First, the influence that the presence or absence of the supply header that blows Ar gas on the heat insulating material has on the effect of suppressing wear will be described.
When the supply header was not provided as in the comparative example shown in Table 1, the average wear rate of the brick was 2.0 (mm / ch), and the wear suppression effect was poor. This is thought to be due to an increase in the brick peeling damage as a result of an increase in the temperature gradient inside the brick due to the insulative cooling effect of the Ar gas not being obtained and the heat insulation of the heat insulating material being reduced. It is done.
On the other hand, as in Reference Example 1 , by providing a supply header, the average wear rate of bricks could be reduced to 1.5 (mm / ch), and the effect of wear control could be greatly improved compared to the comparative example. . This is because the effect of cooling the heat insulating material by Ar gas was obtained, and as a result of maintaining the heat insulating performance of the heat insulating material, it was possible to reduce the peeling damage of the brick.

Next, the influence which the heat insulation of a heat insulating material has on the effect of wear suppression will be described.
Reference Examples 1 to 3 are the results of changing the heat insulation properties by using heat insulation mortar, ceramic fiber, and WDS for the heat insulation materials, respectively, by improving the heat insulation properties (decreasing the thermal conductivity), It was confirmed that an effect of reducing the average wear rate of the brick was obtained ( Reference Example 1 : 1.5 mm / ch, Reference Example 2 : 1.2 mm / ch, Reference Example 3 : 0.7 mm / ch).
In particular, by using a heat insulating material whose thermal conductivity is within the optimum range (0.05 W / (m · K) or less) as in Reference Example 3, the effect of reducing the average wear rate of bricks is maximized. I was able to.

Here, the influence which the structure of the dip tube described in Reference Examples 1 to 3 described above has on the occurrence of defects at the end of operation will be described.
As in Reference Examples 1 to 3 , when the thickness of the heat insulating material is set to be thick (8 mm or more), the dip tube does not approach the remaining thickness of the refractory such as cracks and joint openings after approximately 300 charges at the end of the operation of the dip tube It was confirmed that the reason for replacement occurred. Then, when the dismantling investigation of the refractory was performed after the operation of the dip tube, all of the heat insulating materials initially applied were contracted by 5 mm or more at the maximum. For this reason, it is considered that the gap between the refractory and the cored bar generated by the shrinkage is caused by the joint opening of the brick and the crack of the irregular refractory.
As described above, in Reference Examples 1 to 3 , defects occurred at the end of operation, but the effects of providing a supply header for blowing Ar gas (particularly, the effect of suppressing wear) were compared for the life of these dip tubes. Since it was able to be extended more than an example, it was possible to use a dip tube (overall evaluation: (circle)).

Finally, the influence of the thickness of the heat insulating material on the effect of suppressing wear and the occurrence of defects at the end of operation will be described.
The effect of wear inhibition, as in Reference Example 2 and Example 3, when using a ceramic fiber heat insulating material, also Reference Example 3, as in Examples 1 and 2, in the case of using a WDS in the heat insulating member In either case, there was a tendency that the average wear rate of the brick was slightly increased by reducing the thickness of the heat insulating material, but it was confirmed that a sufficient wear suppression effect was obtained.

Moreover, about the defect at the end of operation, the thickness of a heat insulating material shall be in the optimal range (1 mm or more and 5 mm or less) from Reference Examples 2, 3, and Examples 1-3 without being influenced by the kind of heat insulating material. Thus, it was confirmed that the open joint of the brick and the crack of the irregular refractory did not occur in the dip tube in operation.
In particular, in Examples 1 and 2 , a sufficient wear-inhibiting effect was obtained, and there was no occurrence of defects at the end of operation, so the life of the dip tube could be extended to the maximum (overall evaluation: ◎). .
From the above, by using the dip tube of the degassing apparatus of the present invention, it is possible to suppress the deformation of the core metal and damage to the refractory covering the core metal, and to stably extend the life until the end of the life. It could be confirmed.

As described above, the present invention has been described with reference to the embodiment. However, the present invention is not limited to the configuration described in the above embodiment, and the matters described in the scope of claims. Other embodiments and modifications conceivable within the scope are also included. For example, the case where the dip tube of the degassing apparatus of the present invention is configured by combining some or all of the above-described embodiments and modifications is also included in the scope of the right of the present invention.
Moreover, in the said embodiment, although the case where the cyclic | annular supply header was used was demonstrated, if Ar gas can be sprayed on a heat insulating material, it will not be limited to this, For example, a spiral supply header Or a plurality of straight pipes (supply headers) can be arranged at equal pitches (or different pitches) in the circumferential direction of the dip tube around the axis of the dip tube.

10: Degassing device dip tube, 11: Metal core, 12: Brick (inner refractory), 13: Indeterminate refractory (outer refractory), 14: Support metal, 15: Hollow part, 16: Insulating material, 17, 18: supply header, 19: ejection hole, 20, 21: piping for gas supply, 22-25: supply header

Claims (2)

In the dip tube of the degassing apparatus in which the inner peripheral side refractory and the outer peripheral side refractory are provided on the inner peripheral side and the outer peripheral side of the cylindrical metal core, respectively.
A heat insulating material having a thickness of 1 mm or more and 5 mm or less is disposed between one or both of the inner peripheral refractory and the metal core and between the outer peripheral refractory and the metal core, A dip tube for a degassing apparatus, comprising a supply header for blowing Ar gas toward a heat insulating material. The dip tube of the degassing apparatus according to claim 1, wherein the heat insulating material has a thermal conductivity of 0.05 W / (m · K) or less at an atmospheric temperature of 500 ° C. .

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