JPH08303964A - Leakage sensing sensor in metal melting facility - Google Patents

Abstract

PURPOSE: To prevent an erroneous operation of an alarm by a method wherein a sensor electrode is sealingly enclosed at a protective cap made of specifically selected metal between it and molten metal so as to protect it. CONSTITUTION: A leakage sensing sensor 16 inserted into and loaded at one location or a plurality of locations in a clearance 15 between a crucible 13 storing molten metal 12 therein and an external container 14 is comprised of an insulator 17 and a metalic protection cap 20 inserted into the insulator and for sealingly enclosing a pair of electrodes 19, 19 in a non-contacted state which are projected from the insulator 17 at its extremity end. As a metal constituting raw material of the protection cap 20, it is selected from metal in which its melting point is higher than an operating temperature, although a melting point of alloy when the molten metal 12 is contacted with the cap to make alloy is set to be higher than an operating temperature. Due to this fact, the protection cap 20 is not melted during an operation of a melting furnace, but protects the electrodes 19 and in turn upon contact of it with the leaked molten metal 12, the metal is rapidly melted under the operating temperature to cause the electrodes 19 to be operated, resulting in that a stable operation and a real time sensing of leakage can be realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a leak detecting sensor device in a metal melting facility, that is, a sensor device for detecting a leak of molten metal from a crucible in a metal melting facility using a graphite crucible or the like.

[0002]

2. Description of the Related Art Conventionally, a melting furnace for melting a metal such as aluminum or its alloy, or copper or its alloy has been known. In such a melting furnace, a graphite crucible for melting a metal and containing the molten metal is arranged in a steel container equipped with an electric heater with a gap. The gap is
This is for absorbing the difference in expansion and facilitating the replacement of the crucible, and the graphite crucible and the steel container are both held by a supporting member at several points in the gap.

By the way, since the crucible dissolves metal, it is exposed to a high temperature environment for a long time at all times, and as a result,
It is said that the service life is about 8 to 10 months.

Therefore, there is a problem that the graphite crucible is thinned and weakened at the end of its life, and molten metal leaks from cracks and other partially damaged portions. Since the leaked molten metal flows into the gap, the fact of the leak cannot be visually recognized from the outside.

However, even if the molten metal leaks, if the operation is continued as it is, the molten metal accumulated in the gap causes damage to the steel container, and finally the steel container is broken and the molten metal is exposed to the outside. There is a risk of spillage into and causing a serious accident.

In order to prevent such an accident, it is essential to detect crucible damage in real time. If the cover is closed and the detection is delayed, damage to not only the crucible but also the refractory and the steel container has already progressed, and the replacement parts to be repaired are too wide, which is extremely uneconomical.

[0007]

On the other hand, in order to detect a leak in real time, a detection net formed by arranging a conductive detection element on an insulating sheet is embedded in the furnace wall or furnace bottom, or A leak detection sensor 1 as shown in FIGS. 15 and 16 has been proposed.

The leak detection sensor 1 comprises an element 4 consisting of a pair of conducting wires 3 and 3 inserted through an insulator 2, and an electrode 5 having the conducting wires 3 and 3 protruding from the tip of the element 4. There is. Therefore, the pair of elements 4, 4
Is inserted into the gap 8 formed between the graphite crucible 6 and the steel container 7, and the electrodes 5, 5 of both elements 4, 4 are arranged in the gap 8 in a non-contact state. In FIG. 15, the insulator 2 is composed of a long insulator, and in FIG. 16, the insulator 2 is composed of a large number of short insulators arranged in a row.

Therefore, the graphite crucible 6 is damaged and the molten metal 9
Is leaked and flows into the gap 8, the electrodes 5 and 5 are electrically short-circuited by the leaked molten metal, which can be detected by the detector 10.

However, according to the findings of the present inventors, there is a possibility that such a leak detection sensor 1 may malfunction, and every time a malfunction occurs, the operation must be stopped and the inspection must be performed. I have a serious problem.

That is, as described above, the pair of electrodes 5, 5
Is directly exposed to the operating atmosphere in the gap 8, while in the space of the gap 8, carbon particles separated from the graphite crucible 6 are suspended and carbon dioxide or monoxide is oxidized. It is full of carbon.
Such dissociation of carbon particles becomes remarkable as the graphite crucible 6 is exposed to a high temperature environment for a long period of time. For this reason, even if there is no leakage of molten metal, if carbon particles adhere to and deposit on the electrodes 5 and 5, a short-circuit state between the electrodes 5 and 5 will occur and malfunction will occur. Alternatively, the electrodes 5, 5
Is disposed near the wall surface of the graphite crucible 6 or the steel container 7, the carbon particles grown by adhesion and deposition come into contact with the wall surface, and the electrodes 5 and 5 are short-circuited via the wall surface to cause malfunction. Will be invited.

[0012]

DISCLOSURE OF THE INVENTION The present invention provides a leak detection sensor device in a metal melting facility which solves the above problems.

In view of this, the present invention is configured as a means in which a crucible for containing a metal (N) is placed in an outer container with a gap, and the operating temperature (Ta) in the gap is the melting point of the metal (N). In a metal melting facility which is maintained higher than (mpN), a leak detection sensor provided in the gap is provided with an insulator, and a conductor wire provided with an electrode inserted into the insulator and protruding from the insulator at the tip. And a metal protective cap that seals the electrodes in a non-contact state, and the metal (M) constituting the material of the protective cap is the metal (M).
The melting point (mpM) of the alloy is higher than the operating temperature (Ta), but when the molten metal (N) is brought into contact with the metal (M) to form an alloy, the melting point of the alloy (MN) (L
The point is that it is selected from the metals that make T) lower than the operating temperature (Ta).

In the first embodiment of the present invention, when the main component of the molten metal is Al, the main metal components constituting the metal material of the protective cap are Ag, Au, Cu, Ni,
It can be selected from Fe.

In the second embodiment of the present invention, when the main component of the molten metal is Cu, the metal main component constituting the metal material of the protective cap can be selected from Ni, Ti and Fe.

In the third embodiment of the present invention, when the main component of the molten metal is Zn, the main metal component constituting the metal material of the protective cap can be selected from Al.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described in detail below with reference to the drawings.

As shown in FIG. 1, the metal melting equipment 11 is
The crucible 13 containing the molten metal (N) 12 is placed in the outer container 14 with a gap 15 therebetween, and the operating temperature (T
It keeps a) higher than the melting point (mpN) of the metal (N). Such a metal melting facility 11 is known as a melting furnace for melting metals such as aluminum and its alloys, copper and its alloys, zinc and its alloys, and the crucible 13 is a graphite crucible and the outer container 14 is Although not shown, the outer container 14 is equipped with an electric heater, which is made of a steel container. Note that the crucible 13 and the outer container 14 are mutually supported by a supporting member at several points in the gap 15.

The leak detection sensor device 16 of the present invention is inserted and installed in one or a plurality of places in the gap 15.

(First Embodiment) In the first embodiment shown in FIG. 1, the leak detection sensor device 16 includes an insulator 17
And two conductors 18 that form a pair of electrodes 19 that are inserted into the insulator 17 and project from the insulator 17 at the tip.
a and 18b and a metal protective cap 20 for sealing the electrodes 19 and 19 in a non-contact state.

Such a leak detection sensor device 16 is
For example, a sheath thermocouple, an MI cable, or the like can be used as a basic material, and a hot junction in the case of a thermocouple is not formed at the tip end so that the individual wires do not come into contact with each other and the insulator 17 It can be easily formed by projecting it so that it is exposed from the tip of the. Moreover, as a result, the molten metal (N) in the gap 15
It is possible to endure a high temperature atmosphere corresponding to an operating temperature (Ta) exceeding the melting point (mpN) of 12 and a severe carbonization reducing atmosphere for a long time.

The protective cap 20 is for preventing carbon particles in the atmosphere in the gap 15 from adhering to the electrodes 19, 19, and has a cup shape surrounding the electrodes 19, 19 without contacting them. It is formed and attached to the tip of the insulator 17, which seals the electrodes 19, 19 within the protective cap 20. The protective cap 20
Under the operating temperature (Ta) in the gap 15, the electrodes 19 and 19 are not melted and are in a sealed state. That is, the metal (M) constituting the material of the protective cap 20 has a melting point (mpM) of the metal (M) higher than the operating temperature (Ta). However, when the molten metal (N) 12 leaks from the crucible 13 and comes into contact with the metal (M) that constitutes the protective cap 20, the melting point (LT) of the alloy (MN) produced by alloying there is changed to the melting point (LT). As a result of lowering the operating temperature (Ta), the protective cap 20 melts and shorts the electrodes 19, 19.

A first concrete example based on the first embodiment is shown in FIG.
As shown in (A), it has basically the same configuration as the sheath thermocouple, and the insulator 17 is constituted by the porcelain sheath 22 provided with the pair of insertion holes 21 and 21, and the insertion hole 21,
Electrodes 19 and 19 are formed by projecting the ends of the conductive wires 18 a and 18 b, which are inserted into the wire 21, from the sheath 22 in a state where they are separated from each other, and the protective cap 20 is attached to the distal end of the sheath 22.

A second specific example based on the first embodiment is shown in FIG.
As shown in (B), the conductors 18a and 18b are inserted into the heat-resistant metal or porcelain pipe material 23, and the inside of the pipe material 23 is filled with a filler 24 such as powder having an insulating property. The conductors 18a, 18
The insulator 24 is formed by the filler 24 in which b is embedded. In addition, the conductive wires 18a, 1 inserted through the pipe member 23
The tip portions of 8b are separated from each other by the pipe material 2
3 to thereby form electrodes 19 and 19,
The protective cap 20 is attached to the tip of the pipe material 23.

A third specific example based on the first embodiment is shown in FIG.
As shown in (C), the conductors 18a and 18b are inserted into the metal bottomed pipe material 25 having heat resistance, and
The pipe material 25 is filled with a filler 27 such as powder having an insulating property except for the vicinity of the bottom portion 26 of the pipe 18.
Insulator 17 is formed by a filler 27 in which a and 18b are embedded.
Is composed. The leading ends of the conductive wires 18a and 18b are protruded from the insulator 17 in a state of being separated from each other, and are arranged inside the bottom portion 26 in a non-contact state. Therefore, in the case of the third specific example, the bottom portion 26 integrally formed with the pipe member 25 constitutes the protective cap 20.

In the first embodiment, the molten metal 12
Is detected when the pair of electrodes 19 and 19 are short-circuited. Therefore, as shown in FIG.
The a and 18b are electrically connected to a detector 28 for detecting a short circuit outside the container 11.

(Second Embodiment) In the second embodiment shown in FIG. 2, the leakage detection sensor device 16 includes an insulator 17
And a conductor wire 18 which is inserted into the insulator 17 and which protrudes from the insulator 17 at one end to constitute one electrode 18, and a metal protective cap 20 which seals the electrode 19 in a non-contact state. I have it.

A concrete example of such a second embodiment is shown in FIG.
As shown in (D), the conductive wire 18 is inserted through a heat-resistant metal or porcelain pipe material 29, and a filler 3 such as powder having an insulating property is provided inside the pipe material 29.
Insulator 17 is formed of filler 30 in which conductor 18 is embedded. Pipe material 29
The tip end of the conductive wire 18 inserted in is protruded from the pipe material 29, and thereby constitutes the electrode 19. The protective cap 20 is attached to the tip of the pipe member 29.

In the second embodiment as well, it is needless to say that the same configuration as that shown in FIGS. 4 (A) and 4 (C) described as a specific example of the first embodiment can be adopted, and the two conductors 18 are provided.
It suffices to replace a and 18b with a single conductive wire 18 and appropriately change the design accordingly.

By the way, when carrying out the second embodiment, as shown in FIG. 2, a plurality of leak detection sensor devices 16 of at least two or more are installed in the gap 15. Thereby, when the molten metal 12 leaks, each protection cap 20 melts and short-circuits the electrodes 19, 19 between the plurality of sensor devices 16, 16 so that the leak can be detected. Therefore, the lead wires 18, 18 extending from the plurality of leak detection sensor devices 16, 16 are electrically connected to a detector 28 for detecting a short circuit outside the container 11.

(Third Embodiment) In the third embodiment shown in FIG. 3, the leak detection sensor device 16 includes an insulator 17
And a conductor wire 18 which is inserted into the insulator 17 and which protrudes from the insulator 17 at one end to constitute one electrode 18, and a metal protective cap 20 which seals the electrode 19 in a non-contact state. It is provided and is similar to the second embodiment.

In carrying out this third embodiment,
As shown in FIG. 3, the leak detection sensor device 16 is installed in the gap 1
Insert in 5. A lead wire 18 extending from the leak detection sensor device 16 is electrically connected to a detector 28 outside the container 11, and a short-circuit lead wire 3 that contacts the outer container 14 is provided.
0 is electrically connected to the detector 28. Thus, when the molten metal 12 leaks, the protective cap 20
Is melted to bring the electrode 19 of the sensor device 16 into contact with the outer container 14, so that the electrode 19 is connected to the short-circuit conductor 3
Shorts to 0.

(Structure of Protective Cap) In the present invention,
The protective cap 20 must satisfy long-term durability in an operating atmosphere, while it must dissolve quickly when leaked molten metal 12 comes into contact with the protective cap 20. Therefore, it must be a material selected for the molten metal 12.

In this respect, it is possible to melt the metal material (protective cap 20) having a melting point higher than that of the molten metal 12 with the molten metal 12 if the combination of specific metals is a condition. That is, from a metallurgical point of view, when a metal having a melting point higher than its melting temperature comes into contact with a certain molten metal, there is a combination of metals that diffuses and permeates the molten metal at the interface to lower the melting point. This is similar to the principle when so-called metals are alloyed, and there is a combination of metals that lowers the melting point of the alloyed part.

Therefore, in the case of the construction of the first to third embodiments in which the leak detection sensor 16 is inserted in the gap 15 of the metal melting equipment 11 as described above, the protective cap 20 is made of a metal satisfying the following conditions. It is formed.

That is, the metal (M) constituting the material of the protective cap 20 has its own melting point (mpM) higher than the operating temperature (Ta) in the gap 15, but the metal (M) is When the molten metal (N) is brought into contact with the alloy to be alloyed, the melting point (LT) of the alloy (MN) is selected to be lower than the operating temperature (Ta).

Therefore, since mpM> Ta, the protective cap 20 covers the electrode 19 and protects the electrode 19 without constantly melting it in the gap 15. However, when the molten metal 12 leaks from the crucible 13, the leaked molten metal 12 comes into contact with the protective cap 20, and the metal M forming the protective cap 20 is alloyed there to form an alloy (MN). Since the melting point LT of the alloy decreases and Ta> LT, the protective cap 20 is melted under the operating temperature (Ta) in the gap 15.

(Example of Combination of Molten Metal and Protective Cap) Hereinafter, an example of combination of the metal will be described.

(When the molten metal is aluminum) When the main component (N) of the molten metal 12 is Al, the melting point (mpN) of Al is 660 ° C. Therefore, for example, the operating temperature (Ta) of the melting furnace is set to When the temperature is set to about 800 ° C., the metal main component (M) constituting the metal material of the protective cap 20 is A
It can be selected from one or more of g, Au, Cu, Ni and Fe.

That is, with such a metal (M), as shown in Table 1 below and FIGS. 5 to 9, it is possible to provide the protective cap 20 which can attain the object of the present invention when detecting leakage of molten aluminum. .

[0041]

[Table 1]

(When the molten metal is copper) When the main component (N) of the molten metal 12 is Cu, the melting point (mpN) of Cu is 1083 degrees C. Therefore, for example, the operating temperature (T
When a) is about 1300 ° C., the metal main component (M) constituting the metal material of the protective cap 20 is Ni, Ti,
It can be selected from one or more of Fe.

That is, with such a metal (M), as shown in the following Table 2 and FIGS. 10 to 13, it is possible to provide the protective cap 20 which achieves the object of the present invention when detecting leakage of molten copper. .

[0044]

[Table 2]

(When the molten metal is zinc) When the main component (N) of the molten metal 12 is Zn, the melting point of Zn (mpN)
Is 419 degrees C. Therefore, for example, the operating temperature (T
When a) is about 500 ° C., the metal main component (M) constituting the metal material of the protective cap 20 can be selected from Al.

That is, with such a metal (M), as shown in Table 3 and FIG. 14 below, it is possible to provide the protective cap 20 that achieves the object of the present invention when detecting leakage of molten zinc.

[0047]

[Table 3]

[0048]

According to the present invention, since the electrode 19 is sealed and protected by the protective cap 20, the carbon particles and other dusts found in the graphite crucible and the like adhere to the electrode 19 to cause a short circuit. However, there is no malfunction such as issuing an alarm even though there is no fact of leakage of molten metal.

In particular, according to the invention, the protective cap 20
Consists of a metal (M) selected in particular between the molten metal (N) 12 and the metal (M) has a melting point (mpM) of itself higher than the operating temperature (Ta). However, when the leaked molten metal (N) contacts the metal (M) to form an alloy, the melting point (LT) of the alloy (MN) is selected from the metals that lower the operating temperature (Ta). There is.
Therefore, the protective cap 20 protects the electrode 19 without being melted during the operation of the melting furnace, but when contacted with the leaked molten metal 12, the protective cap 20 is rapidly melted under the operating temperature, and the electrode 19 is not melted. It is extremely excellent as it can realize stable operation and real-time detection of leakage.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a first embodiment of the present invention.

FIG. 2 is a vertical sectional view showing a second embodiment of the present invention.

FIG. 3 is a vertical sectional view showing a third embodiment of the present invention.

FIG. 4 shows a specific example of a leak detection sensor device,
(A) is a longitudinal sectional view of a first specific example based on the first embodiment,
(B) is a vertical sectional view of a second specific example based on the same aspect, (C) is a vertical sectional view of a third specific example based on the same aspect, and (D) is a vertical sectional view of a specific example based on the second embodiment. is there.

FIG. 5 is a graph showing a liquidus line of an Ag—Al alloy.

FIG. 6 is a graph showing a liquidus line of an Al—Au alloy.

FIG. 7 is a graph showing a liquidus line of an Al—Cu alloy.

FIG. 8 is a graph showing a liquidus line of an Al—Ni alloy.

FIG. 9 is a graph showing a liquidus line of an Al—Fe alloy.

FIG. 10 is a graph showing a liquidus line of a Cu—Ni alloy.

FIG. 11 is a graph showing a liquidus line of a Cu—Ti alloy.

FIG. 12 is a graph showing a liquidus line of a Cu—Fe alloy.

FIG. 13 is a graph showing a liquidus line of an Al—Zn alloy.

FIG. 14 is a vertical cross-sectional view showing a conventional leak detection sensor device.

FIG. 15 is a vertical cross-sectional view showing a conventional leak detection sensor device.

[Explanation of symbols]

 11 Metal Melting Device 12 Molten Metal 13 Crucible (Graphite Crucible) 14 Outer Container (Steel Container) 15 Gap 16 Leak Detection Sensor Device 17 Insulator 18, 18a, 18b Conductor Wire 19 Electrode 20 Protective Cap

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[Procedure amendment]

[Submission date] May 11, 1995

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction content]

[0007]

On the other hand, in order to detect a leak in real time, a detection net formed by arranging a conductive detection element on an insulating sheet is embedded in a furnace wall or a furnace bottom, or A leak detection sensor 1 as shown in FIGS. 14 and 15 has been proposed.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction content]

The leak detection sensor 1 comprises an element 4 consisting of a pair of conducting wires 3 and 3 inserted in an insulator 2, and an electrode 5 having the conducting wires 3 and 3 protruding from the tip of the element 4. There is. Therefore, the pair of elements 4,
4 is a gap 8 formed between the graphite crucible 6 and the steel container 7.
The electrodes 5 and 5 of both elements 4 and 4 are arranged in the gap 8 in a non-contact state. In addition, in FIG.
The insulator 2 is composed of a long insulator, and in FIG. 15 , the insulator 2 is composed of a large number of short insulators arranged in a row.

Claims (4)

[Claims] 1. A crucible for containing a metal (N) is arranged in an outer container with a gap, and an operating temperature (Ta) in the gap is maintained higher than a melting point (mpN) of the metal (N). In a metal melting facility, a leak detection sensor provided in the gap seals an insulator, a conductor wire that is inserted into the insulator and has an electrode protruding from the insulator at the tip, and the electrode in a non-contact state. The metal (M) constituting the material of the protective cap has a melting point (mpM) of the metal (M) higher than the operating temperature (Ta). When the molten metal (N) is brought into contact with the metal (M) to form an alloy, the alloy (M-
A leak detection sensor device in metal melting equipment, characterized in that it is selected from the metals whose melting point (LT) of N) is lower than the operating temperature (Ta). 2. The main component of the molten metal is Al, and the main metal component constituting the metal material of the protective cap is A
The leak detection sensor device in the metal melting facility according to claim 1, wherein the leak detection sensor device is selected from g, Au, Cu, Ni, and Fe. 3. The main component of the molten metal is Cu, and the main metal component of the metal material of the protective cap is N.
The leak detection sensor device in the metal melting facility according to claim 1, wherein the leak detection sensor device is made of i, Ti, or Fe. 4. The main component of the molten metal is Zn, and the main metal component of the metal material of the protective cap is Al.
The leak detection sensor device in the metal melting facility according to claim 1, wherein the leak detection sensor device comprises: