JP3128089B2 - Structure of porous plug for molten metal container - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a porous plug used for a molten metal container such as a ladle, and more particularly to a structure of a porous plug capable of measuring a remaining height.

[0002]

2. Description of the Related Art A porous plug is disposed at the bottom of a molten metal container such as a ladle, and is used to blow gas into the molten metal. The porous plug is formed of a highly breathable refractory, and its tip is exposed in the molten metal. For this reason, the tip of the porous plug is eroded by high heat, and the remaining height is gradually reduced. If the length of the porous plug is shorter than the limit value, the molten metal leaks from the mounting portion of the porous plug, causing serious damage.

[0003] Since the state of loss of the porous plug in the container cannot be directly visually checked, it is necessary to estimate the state of loss from the operating time or the like and replace the porous plug. However, the amount of the porous plug lost depends on various operating conditions. Therefore, it is necessary to replace the porous plug as soon as possible in consideration of safety. For this reason, it is necessary to replace it even though it can be used originally, and there is a problem that economic efficiency is low.

On the other hand, in various furnaces such as a blast furnace and a heating furnace,
A method of detecting the falling off of the furnace wall using the reflection of ultrasonic waves,
This is known from JP-A-55-162593. The furnace wall falling detection method described in the publication discloses a method in which a detection rod is buried in a furnace wall in a horizontal direction, ultrasonic waves are incident on the detection rod from outside the furnace, and a change in a reflection signal is caused by falling of the furnace wall. The bent state of the detecting rod is detected, and the falling state of the furnace wall is known from this.

[0005]

However, in the method of detecting a furnace wall falling off described in the above publication, the falling state of the furnace wall is detected from the bent state of the detection rod. If the detection rod does not bend, it cannot be detected. Further, since the detection rod is bent by the weight of the furnace wall that has fallen, the arrangement direction of the detection rod is restricted to the horizontal direction. Further, when the detection rod comes into contact with the molten metal as the furnace wall falls off, the temperature of the detection rod becomes extremely high, and the ultrasonic propagation characteristics of the detection rod deteriorate, so that accurate measurement cannot be performed. Also, since the temperature of the detection rod changes between the state in which the detection rod is completely embedded in the furnace wall and the state in which the detection rod is exposed to the molten metal, the ultrasonic wave propagation characteristics also change. From this point, there is a problem that accurate measurement is difficult. Therefore, the method for detecting the falling off of the furnace wall described in the above publication cannot be directly used for detecting the remaining height of the porous plug.

Accordingly, an object of the present invention is to accurately detect the remaining height of a porous plug using ultrasonic waves.

[0007]

In order to achieve the above object, the structure of the porous plug for a molten metal container according to the present invention is to provide a waveguide rod for ultrasonic measurement which is lost at the same degree of progress as the porous plug. Is provided integrally with the porous plug.

[0008] The waveguide rod for ultrasonic measurement can be disposed with one end face exposed inside the furnace and the other end face exposed outside the furnace.

Further, the structure of the porous plug for a molten metal container according to the present invention is such that the waveguide rod for ultrasonic measurement is positioned inside the porous plug whose one end surface is separated from the tip of the porous plug by a predetermined distance. Alternatively, it can be arranged with the other end face exposed outside the furnace.

[0010]

According to the present invention, when the height of the porous plug decreases due to the high heat due to the operation, the waveguide rod for ultrasonic measurement also melts and its length becomes shorter. . When ultrasonic waves are applied to the waveguide from outside the furnace, the state of reflected ultrasound changes according to the length of the waveguide. Therefore, the remaining height of the porous plug can be determined by measuring the state of the reflected ultrasonic waves. In addition, since the gas passes through the porous plug, the waveguide rod formed integrally with the porous plug is cooled by the gas, and good ultrasonic wave propagation characteristics are maintained. The boundaries can be clearly detected.

In the case where the waveguide rod for ultrasonic length measurement is disposed with one end face thereof being separated from the tip of the porous plug by a predetermined distance, the waveguide rod at the start of operation. One end face is not in contact with the high-temperature molten metal, and does not become so hot due to the cooling effect of the gas flowing around the waveguide rod. can get. When the porous plug is melted and reaches one end face of the waveguide rod, the one end face of the waveguide rod is heated to a high temperature and melts, and does not function sufficiently as a reflection surface of the ultrasonic wave, and the reflected wave is reduced. That is, when the remaining height of the porous plug reaches the usage limit, the magnitude of the reflected wave is sharply reduced. Therefore, by measuring the magnitude of the reflected ultrasonic waves, it can be determined whether or not the porous plug has reached the remaining height.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The features of the present invention will be specifically described below based on embodiments with reference to the drawings.

FIG. 1 shows a first embodiment of a porous plug for a molten metal container according to the present invention. FIG. 1 (a) is a top view of the porous plug, and FIG. 1 (b) is a cross section of the porous plug. FIG. 3C is a cross-sectional view taken along the line II of FIG. In this embodiment, a ladle is used as a molten metal container, and a porous plug is attached to the bottom of the ladle.

On the ladle bottom plate 1, a perm brick 2 and a ladle bottom brick 3 are laminated. Ladle bottom plate 1, perm brick 2 and ladle bottom brick 3 are formed with through holes 4 for allowing porous plugs to penetrate, and portions corresponding to through holes 4 of ladle bottom brick 3 have conical shapes. A brick 6 having a through hole 5 is provided. Ladle bottom plate 1
On a lower surface of a portion corresponding to the through hole 4, a receiving metal member 7 for detachably attaching a porous plug is fixed by welding or the like.

The porous plug 8 includes a round rod-shaped porous element 9 made of a refractory such as high-alumina brick having high air permeability, a substantially conical castable 10 provided on the outer periphery of the porous element 9, and a castable There is provided a plug body 12 comprising a substantially conical metal case 11 which covers the airtight state 10 except for an upper end portion, and a gas blowing pipe 13 is connected to a bottom surface of the metal case 11.

Furthermore, a waveguide rod 14 for measuring the length of the ultrasonic wave, which has good propagation characteristics with respect to the ultrasonic wave and is lost at the same degree of progress as the porous plug 8, is integrated inside the porous plug 8. It is arranged in the form. Specifically, steel, SU
A waveguide rod 14 made of any of S, non-ferrous metal, alloy, fine ceramics (dense), molten ceramics (including glass, quartz, etc.) is provided along the porous element 9 on the inner periphery of the castable 10. Embedded. The waveguide rod 14 is drawn downward through a through hole 11 a formed in the bottom of the metal case 11. The sealing structure between the metal case 11 and the waveguide rod 14 is preferably welded if possible, and if impossible, a seal using ceramic fiber is used. However, if the airtightness can be maintained, only the castable 10 may be used.

FIGS. 2A and 2B show the waveguide rod 14.
As shown in FIG. 5, small triangular cuts 14b, 14c, 14d are formed at a constant interval L from the initial end face 14a exposed in the furnace, for example, at 50 mm intervals. The most proximal side, that is, the cut 14d on the measurement end surface 14e side
Are formed at the limit position of the remaining height of the porous plug 8.

A plug holder 15 is provided below the plug body 12, and the presser holder 1 is provided to the plug receiver 15 via a desired number of height adjustment disks 16.
7 is pressed down.

As shown in FIG. 1 (c), the plug brick 15 has a through hole 15a for passing a gas blowing pipe 13 at the center thereof and a through hole 15a for passing a waveguide rod 14 as shown in FIG. Long groove 15 provided in communication with
The gas injection pipe 13 and the waveguide rod 14 are drawn out of the container through the plug brick 15, the height adjustment disk 16 and the holding hardware 17.

The holding member 17 and the receiving member 7 have a bayonet structure, and the wing 17a provided on the holding member 17 is aligned with a notch (not shown) formed in the receiving member 7. In the state, the plug body 12, the plug receiver 15, the height adjustment disk 16 and the holding hardware 17 are provided.
The porous plug 8 composed of the porous plug 8 is pressed against the brick 6 and rotated, so that the porous plug 8
Is attached.

A probe 18 composed of an ultrasonic transducer is attached to the leading end of the waveguide rod 14, that is, the measurement end face 14e (see FIG. 2A). Is connected to the ultrasonic measuring device 19 as shown in FIG. The probe 18 is driven at a predetermined cycle by the ultrasonic length measuring device 19, and the ultrasonic waves from the probe 18 are transmitted to the waveguide rod 14. The reflected wave from the waveguide rod 14 is detected by the probe 18 and sent to the ultrasonic length measuring device 19, and the state of reflection is measured by the cathode ray tube 19a.

The cross section of the waveguide rod 14 is preferably as small as possible, but if it is too small compared to the contact surface with the probe 18, the ultrasonic waves transmitted from the probe 18 will not be guided. In some cases, transmission to the rod-like body 14 becomes difficult. In this case, the measurement end face 14e at the end on the pull-out side of the waveguide rod 14 is used.
2 (c) and 2 (d), the vicinity of the side end is tapered as shown in FIG.
As shown in (f), the contact surface of the probe 18 needs to be tapered to be small. Further, the probe 18 may not always be attached to the measurement end surface 14e, but may be pressed only when measurement is necessary.

Next, the operation of the above-described porous plug 8 for a molten metal container will be described.

The probe 18 attached to the measurement end face 14e of the waveguide rod 14 is driven at a predetermined period by an ultrasonic length measuring device 19, and the ultrasonic waves generated by the probe 18 Along, mainly reflected at the end face 14a,
Partially cuts 14b, 1 formed in the waveguide rod 14
The light is reflected at 4c and 14d. The reflected ultrasonic wave from the waveguide rod 14 is converted into an electric signal by the probe 18 and sent to the ultrasonic measuring device 19. In the ultrasonic length measuring device 19, a cathode ray tube 19 displaying the horizontal axis as the time axis and the vertical axis as the reflection intensity
The reflection state of the ultrasonic wave is measured at a.

In the initial state, the ultrasonic wave is mainly reflected by the initial end face 14a of the waveguide rod 14, and therefore, the ultrasonic wave shown in FIG.
As shown in FIG. 7, a reflected wave _PT having a large amplitude is observed at a position corresponding to the initial end face 14a of the waveguide rod 14. Also,
Cuts 14b, 14c, small reflected waves P _b generated by 14d, P _c, P _d is also observed.

When the operation is started, the tip of the porous plug 8 is melted and the tip of the waveguide rod 14 is also melted by the high heat. Therefore, as the remaining height of the porous plug 8 decreases, the length of the waveguide rod 14 also decreases. For this reason, the reflection time of the ultrasonic wave is shortened, and as shown in FIG. 5, the position of the reflected wave _{PT having} a large amplitude generated at the end of the waveguide rod 14 moves to the transmission end side (left side in the figure). I do. By observing the position of the reflected wave _{PT with} the ultrasonic measuring device 19, the remaining height of the porous plug 8 can be known. At this time, in addition to the reflected wave _{PT having} a large amplitude generated at the end of the waveguide rod 14, the cuts 14b, 14
c, a small reflected wave P with a constant amplitude generated at 14d
_{Since b} , _Pc , and _Pd (see FIG. 4) are also observed, the remaining height of the porous plug 8 can be accurately known by referring to these reflected waves. When the remaining height of the porous plug 8 reaches the limit, that is, the reflected wave P
Position of _T is Once reached the position of the reflected wave P _d, to replace the porous plug 8.

The porous plug 8 utilizing the reflection of ultrasonic waves
In order to know the remaining height, the waveguide rod 14 must transmit ultrasonic waves well. That is, not only the furnace inner end surface but also each part must have sufficient hardness. Since the waveguide rod 14 is arranged in contact with the molten metal, it becomes extremely hot. In general, the hardness of a substance decreases at a high temperature, so that the propagation efficiency and reflection efficiency of ultrasonic waves decrease. Here, in this embodiment,
Since the waveguide rod 14 is provided integrally with the porous plug 8 through which the gas passes, the waveguide rod 14 is cooled by the gas passing through the porous plug 8, and the hardness of the waveguide rod 14 is maintained while maintaining the hardness of the waveguide rod 14. Sound waves can be propagated and reflected well.

Since the end of the waveguide rod 14 is in contact with or very close to the molten metal, cooling by the gas becomes insufficient and the ultrasonic wave may not be reflected well. In this case, the reflected wave P _T from the end face is difficult to be observed by the cathode ray tube 19a, but the reflected waves P _b , P _c , from the cuts 14b, 14c, 14d that are sufficiently cooled.
_Pd is clear, and it can be confirmed that the remaining portion of the porous plug 8 includes at least the cut 14b.

In the above-described first embodiment, the waveguide rod 14 is embedded in the inner periphery of the castable 10 along the porous element 9. However, the present invention is not limited to this structure and will be described below. Various structures can be adopted. Note that the same reference numerals are given to members and the like corresponding to the first embodiment.

FIGS. 6 (a) and 6 (b) are a top view and a sectional view of a main part of a second embodiment of the porous plug according to the present invention. A long groove 9a is formed, and the waveguide rod 14 is inserted into the long groove 9a.
Is stored.

FIGS. 7A and 7B are a top view and a sectional view of a main part of a porous plug according to a third embodiment of the present invention. The gas injection pipe 1 is provided through the central axis.
3 is led out from the side wall.

FIG. 8 is a sectional view of a fourth embodiment of the porous plug according to the present invention. The waveguide rod 14 is provided so as to pass through the castable 10 away from the porous element 9. And is led out from the bottom surface of the metal case 11.

FIG. 9 is a sectional view of a porous plug according to a fifth embodiment of the present invention. A long groove 10a is formed along the axis on the outer periphery of the castable 10, and a waveguide rod is formed in the long groove 10a. The body 14 is housed in a state of being inscribed in the metal case 11, and is led out from the bottom surface of the metal case 11. Note that the waveguide rod 14 may be provided in a state of circumscribing the metal case 11.

In each of the above-described embodiments, the waveguide rod 14 for ultrasonic measurement is disposed with one end face exposed to the inside of the furnace and the other end face exposed to the outside of the furnace. As in the sixth embodiment shown in FIG. 10, the waveguide rod 20 is placed in a state in which one end face is located inside the porous plug at a predetermined distance from the tip of the porous plug and the other end face is exposed outside the furnace. It can also be arranged in. However, the waveguide rod-like body 20 does not necessarily need to be made of a material that can be lost at the same degree of progress as the porous plug, as long as it can be lost.

In the sixth embodiment shown in FIG. 10, the initial end face 20a of the waveguide rod 20 is not exposed in the furnace, and is located at a position retreated a predetermined distance M from the tip of the porous plug. The end face 20 a is in a state of being embedded in the porous element 9. The predetermined distance M corresponds to a distance obtained by subtracting the usable height from the initial height of the porous plug.

At the start of the operation, the initial end face 20a of the waveguide rod 20 is not in contact with the molten metal.
0a is not so hot. Therefore, the initial end face 20a functions sufficiently as a reflecting surface of the ultrasonic wave, and a large reflected wave _PT is obtained as shown in FIG. When the porous plug is melted and the initial end face 20a is exposed to the molten metal or in a state immediately before the exposure, the initial end face 20a becomes hot and starts to be melted, and does not function sufficiently as a reflecting surface of ultrasonic waves. As shown in the figure, the reflected wave P _T ′ becomes smaller or disappears. Therefore, by observing the reflected wave from the end face with the cathode ray tube 19a, it can be understood that when the magnitude of the reflected wave sharply decreases, the remaining height of the porous plug has reached the use limit. As described above, in the sixth embodiment, only the magnitude and presence / absence of the reflected wave need to be binaryly observed, so that the state of the porous plug can be easily determined.

In the sixth embodiment, the fact that the reflection characteristic of the initial end face 20a of the waveguide rod 20 is greatly deteriorated by high heat is positively utilized, and the remaining height of the porous plug is reduced by the magnitude of the reflected wave. It is determined whether the usage limit has been reached. Therefore, in a high temperature state in which the molten metal exists in the furnace, the state of the porous plug can be reliably detected.

The arrangement of the waveguide rod 20 is shown in FIG.
However, the present invention is not limited to the structure shown in FIG. 0, and in each of the first to fifth embodiments described above, instead of each of the waveguide rods 14, a waveguide rod whose initial end face 20a is not exposed to the furnace is used. The body 20 can be used. However, the space between the initial end face 20a of the waveguide rod 20 and the tip of the porous plug is the same as the substance surrounding the waveguide rod 20, so that the molten metal does not contact the initial end face 20a at the start of operation. Alternatively, it must be filled with another suitable substance.

[0039]

As described above, in the present invention, since the waveguide rod for ultrasonic measurement which is eroded by heat is used, the remaining height of the porous plug provided at the bottom of the container is also increased. Can be accurately known, and it is possible to prevent erroneous determination of the usage limit from causing enormous damage. In addition, since the waveguide rod is provided integrally with the porous plug, the waveguide rod is sufficiently cooled by the gas passing through the porous plug, and excellent ultrasonic wave propagation characteristics of the waveguide rod are maintained. The remaining height can be accurately known even in the environment.

[Brief description of the drawings]

FIG. 1 is a view showing a first embodiment of a porous plug for a molten metal container of the present invention.

FIG. 2 is a perspective view showing various waveguide rods and contacts used in the porous plug of the present embodiment.

FIG. 3 is an explanatory diagram showing a connection relationship between a probe attached to a waveguide rod and an ultrasonic length measuring device.

FIG. 4 is an explanatory diagram showing a measurement example in an ultrasonic measuring device in an initial state.

FIG. 5 is an explanatory diagram showing a measurement example with an ultrasonic length measuring device when a porous plug is lost.

FIG. 6 is a view showing a main part of a second embodiment of the porous plug for a molten metal container of the present invention.

FIG. 7 is a view showing a main part of a third embodiment of the porous plug for a molten metal container of the present invention.

FIG. 8 is a view showing a main part of a fourth embodiment of the porous plug for a molten metal container of the present invention.

FIG. 9 is a view showing a main part of a fifth embodiment of the porous plug for a molten metal container of the present invention.

FIG. 10 is a view showing a main part of a sixth embodiment of the porous plug for a molten metal container of the present invention.

FIG. 11 is an explanatory diagram showing a measurement example with an ultrasonic length measuring device in an initial state in a sixth embodiment.

FIG. 12 is an explanatory diagram showing a measurement example with an ultrasonic length measuring device when a porous plug is lost in a sixth embodiment.

[Explanation of symbols]

1: Ladle bottom plate, 2: Perm brick, 3: Ladle bottom brick,
4: Through hole, 5: Through hole, 6: Brick, 7: Hardware, 8: Porous plug, 9: Porous element, 9
a: long groove, 10: castable, 10a: long groove, 11:
Metal case, 11a: through hole, 12: plug body, 1
3: gas injection pipe, 14: waveguide rod, 14a:
Initial end faces, 14b, 14c, 14d: cut, 14
e: measuring end face, 15: plug receiving brick, 15a: through hole, 15b: long groove, 16: height adjustment disk, 17: holding metal, 17a: wing, 18: probe, 19: ultrasonic measuring device , 19a: cathode ray tube, 20: waveguide rod, 2
0a: Initial end face

Continuation of the front page (56) References JP-A-63-56963 (JP, A) JP-A-1-153384 (JP, A) JP-A-4-231172 (JP, A) JP-A-57-122751 (JP) , U) Fully open 1988-56962 (JP, U) Fully open 1988-63,737 (JP, U) Fully open 1988-202470 (JP, U) Fully open, 2-48243 (JP, U) Fully open 3-68959 (JP, U) Japanese Utility Model 3-68960 (JP, U) Japanese Utility Model 3-85159 (JP, U) Japanese Utility Model 3-91169 (JP, U) Japanese Utility Model 5-10444 (JP, U) U) Japanese Utility Model Hei 5-54533 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B22D 41/58 B22D 11/10 360 C21C 7/072 G01B 17/00

Claims (3)

(57) [Claims] 1. A structure of a porous plug for a molten metal container, wherein a waveguide rod for ultrasonic measurement, which is melted at the same degree of progress as the porous plug, is disposed integrally with the porous plug. 2. The waveguide rod for ultrasonic measurement according to claim 1, wherein one end face is exposed inside the furnace and the other end face is exposed outside the furnace. The structure of the porous plug for a molten metal container described in the above. 3. A waveguide rod for ultrasonic length measurement, wherein one end face is located within a porous plug separated by a predetermined distance from the tip of the porous plug, and the other end face is exposed outside the furnace. The structure of a porous plug for a molten metal container characterized by being carried out.