JPH09303971A - Hot water leakage detector for induction melting furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily decide whether the operation of a molten metal leakage detector depends on the deposition of zinc or the leakage of molten metal by respectively providing molten metal leakage detecting nets on both sides of the boundary surface of a molten metal holding lining and a coil holding lining and connecting them to a detector. SOLUTION: A coil holding lining 3 formed with castable cement in a cylindrical shape is provided on the outer periphery of a melting chamber 2 made of a molten metal holding lining 1 obtained by burning powder fireproof material. A water cooled heating coil 4 is wound on the outer periphery thereof. Then, a needle electrode 7 is buried on the bottom surface of the inside of the melting chamber 2 so as to expose its end. Molten metal leakage detecting nets 8A and 8B are buried on both sides of the boundary surface 14 of the molten metal holding lining 1 and the coil holding lining 3. Further, the molten metal leakage detecting nets 8A and 8B and the electrode 7 are connected in series through a switch device 13, a DC power source 9, a detector and a recorder.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molten metal leak detection device for an induction melting furnace.

[0002]

2. Description of the Related Art Generally, as shown in FIG. 4, an induction melting furnace has a cylindrical coil holding lining 3 on the outer periphery of a melting chamber 2 formed in a crucible shape by a molten metal holding lining 1 made by stamping powder refractory material. The heating coil 4 is wound around it, and the return path core 5 is vertically attached to the outer periphery of the heating coil 4 at a predetermined interval, and the outer side of the core 5 is surrounded by the furnace frame 6. By supplying an alternating current to the heating coil 4, the metal introduced into the melting chamber 2 is induction-heated and melted.

In such an induction melting furnace, the melting chamber 2
Molten metal holding lining 1 made of refractory material
However, the long-term operation of the furnace may cause erosion and wear gradually, or the refractory material may crack and the high temperature molten metal may leak to the outside. Since this molten metal leak leads to a serious accident, it is necessary to detect this precursor and repair the furnace before the molten metal leak occurs. For this reason, various detecting devices for detecting a leak of hot water are attached to conventional equipment.

In this molten metal leak detection device, a needle-shaped electrode 7 is embedded on the inner bottom surface of the melting chamber 2 so that its tip is exposed.
And a molten metal leak detection net 8 embedded in the molten metal holding lining 1 of the melting chamber 2, a DC power source 9 connected to these electrodes 7 and the molten metal leak detection net 8, a detector 10 and a recorder 11. There is. The hot water leak detection net 8 has a structure in which detection elements are embedded in parallel in a belt-shaped insulating sheet at predetermined intervals, and the ends are connected.

In this molten metal leak detection device, a small amount of electric current flows in a normal state, but when the refractory material forming the melting chamber 2 is eroded and the furnace wall becomes thin or cracked, the molten metal 6
The resistance between the molten metal leak detection network 8 and the molten metal leak detection network 8 changes, and the current flowing through the detection circuit increases, so that the state of the furnace wall can be measured. When the molten metal 12 comes into contact with the molten metal leak detection net 8 due to erosion, the detection circuit is short-circuited and the detector 10
It is supposed to generate an alarm from.

When the cast iron or the cast steel is melted, this detector can detect it almost accurately according to the erosion condition of the furnace wall. However, when the copper alloy, especially brass containing zinc is melted. In addition, since the refractory material that constitutes the molten metal holding lining 1 is porous and zinc has a low boiling point of 906 ° C, zinc vapor in the molten metal holding lining 1
There is a problem of lateral penetration.

Further, the coil holding lining 3 is formed of castable cement in a high-strength dense chamber so that zinc vapor does not easily penetrate, and the coil holding lining 3 has its heating coil 4 wound around its outer periphery cooled by cooling water. Since the coil holding lining 3 is also cooled,
The zinc vapor is cooled on this inner peripheral surface and metallic zinc is deposited and stays there. Therefore, in this state, a current flows between the molten metal leak detection net 8 and the molten metal 6 and the pointer of the detector 10 largely fluctuates, but it is necessary to judge whether the cause is the deposited zinc or the molten metal 6 leaks. I can't.

For this reason, conventionally, when the pointer of the detector 10 largely fluctuates, the operation is stopped and the furnace is repaired for safety. However, as a result of dismantling the furnace, it is possible that zinc is deposited instead of molten metal leak. There was a case where unnecessary repair work was performed.

[0009]

SUMMARY OF THE INVENTION The present invention eliminates the above-mentioned drawbacks, and when the molten metal leak detection device is activated, it is possible to easily determine whether it is due to zinc deposition or molten metal leakage. Therefore, it is an object of the present invention to provide a molten metal leak detection device for an induction melting furnace, which enables efficient and safe operation by eliminating unnecessary furnace replacement work.

[0010]

According to a first aspect of the present invention, there is provided a molten metal leak detection device for an induction melting furnace, wherein a coil holding lining is provided outside a molten metal holding lining forming a melting chamber, and heating is further provided outside the coil holding lining. In an induction melting furnace in which a coil is wound, hot water leak detection nets are arranged on both sides of the boundary surface between the molten metal holding lining and the coil holding lining, and these hot water leak detection nets are connected to a detector. To do.

The molten metal leak detection device of the induction melting furnace of the present invention is
When melting an alloy containing a metal with a low boiling point such as zinc, zinc evaporates at a temperature where the boiling point is lower than the melting temperature of the alloy and penetrates the molten metal holding lining formed of a porous powdery refractory material, Zinc vapor comes into contact with the coil holding lining cooled by the heating coil and is cooled, and metallic zinc is deposited at the interface with the molten metal holding lining. When a large amount of metallic zinc is thus deposited, the detector connected to one of the molten metal leak detection nets embedded in the molten metal holding lining is activated.

When the pointer of the detector swings to full scale, look at the meter of the detector connected to the other molten metal leak detection network embedded in the coil holding lining. At this point, it cannot be determined whether it is due to the precipitation of zinc or the leakage of molten metal. If there is no change in the deflection of the pointer of the detector connected to the other molten metal leak detection network even after the operation continues for a while, it can be determined that the cause is zinc deposition.

When the pointer of the detector connected to the other molten metal leak detection network is shaken while continuing the operation, it can be determined that the molten metal holding lining is eroded and the furnace wall is thinned or molten metal is leaked. , Stop the operation at the warning point, dismantle the furnace, and replace the furnace.

Further, in the molten metal leak detection device according to the second aspect, when one molten metal leak detection net arranged on the molten metal holding lining side detects a molten metal leak state, the other molten metal leak arranged on the coil holding lining side. The position of the pointer of the detector connected to the detection network is used as a warning start point, and if the pointer starts to sway from this point, it can be easily detected that the molten metal has leaked.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention is shown in FIG.
This will be described in detail with reference to FIG. As shown in FIG. 1, the structure of the melting furnace is such that a melting chamber 2 is formed by a molten metal holding lining 1 obtained by sintering a powder refractory material, and a coil holding lining 3 formed in a cylindrical shape by castable cement is provided on the outer periphery thereof. , And the water-cooled heating coil 4 around this outer circumference
Is wound. The other structure is the same as that of FIG.

As shown in FIG. 2, the molten metal leak detecting device has a needle-shaped electrode 7 buried in the inner bottom surface of the melting chamber 2 so that its tip is exposed, and a boundary between the molten metal holding lining 1 and the coil holding lining 3. Hot water leak detection net 8A on both sides of the surface 14
8B is buried, and these hot water leak detection networks 8A and 8B and the electrode 7 are provided with a switch 13, a DC power source 9, a detector 10 and a recorder 11.
Are connected in series via.

In the induction melting furnace having the above construction, since the refractory material contains water when the furnace is built, the internal resistance of the molten metal holding lining 1 is small when the DC power supply 9 is turned on, so that the molten metal buried in the molten metal is lined up here. When the switch 13 is switched to the side of the leak detection network 8A, the detector 10 has a pointer 16 as shown in (A1) of FIG.
Swings a lot. Further, when the hot water leak detection net 8B embedded in the coil holding lining 3 is switched to the side of the hot water leak detection net 8B, the pointer 16 of the detector 10 largely shakes as shown in (A2) of FIG. After this,
As the operation is repeated, the water content of the refractory material evaporates and dries, and the pointer 16 of the detector 10 shows little fluctuation in both the hot water leak detection nets 8A and 8B as shown in (B1) and (B2) of FIG. Become.

When melting a copper alloy containing zinc, zinc has a low boiling point, so that it evaporates at a low temperature and penetrates the molten metal holding lining 1 formed of a porous powdery refractory material.
Zinc vapor comes into contact with the coil holding lining 3, which is cooled by the water-cooled heating coil 4 and is made of castable cement in the high-strength dense chamber, and is cooled there. Is deposited.

When a large amount of metallic zinc is deposited in this way, the detector 10 connected to the molten metal leak detection net 8A embedded in the molten metal holding lining 1 has a pointer 16 as shown in (C1) of FIG.
Swings a lot, and finally swings to full scale. In such a state, if the switching device 13 is switched to the hot water leak detection net 8B embedded in the coil holding lining 3, the detector is switched.
As shown in (C2) of FIG. 3, the pointer 10 is in a state in which the pointer 16 is swung to a substantially middle position. At this point, it is not possible to determine whether it is due to the precipitation of zinc or the leakage of the molten metal 12, but the position of the pointer 16 at this time is set as the warning start point S.

Even if the operation is continued for a long time,
When the states of (C1) and (C2) in FIG. 3 do not change, it can be determined that the cause is zinc deposition, and the switching device is used as it is.
The operation can be continued with 13 being connected to the hot water leak detection network 8B.

When the molten metal holding lining 1 is further eroded and the furnace wall is thinned or cracked due to further operation, the molten metal leak detection net 8B and the molten metal 12 embedded in the coil holding lining 3 are melted.
The resistance between the detector 10 and the detector 10 decreases and the current flowing through the detector 10 increases.
(D2), the pointer 16 starts to swing from the warning start point S, and it can be determined that hot water leakage has occurred. When the pointer 16 reaches the stop point E, the operation is stopped, the furnace is dismantled, and the furnace is replaced.

In this way, two hot water leak detection nets 8A and 8B are provided, and when the hot water leak detection net 8A operates, the hot water leak detection net 8B embedded in the coil holding lining 3 where zinc is difficult to penetrate is switched to the hot water leak detection net 8B. By operating with caution, you can judge whether it is due to zinc precipitation or due to hot water leakage, there is no need to perform wasteful furnace replacement due to zinc precipitation, and it is easy to plan to replace furnaces on holidays Therefore, the operating rate can be improved.

In the above description, the case in which the switch 13 is provided and the detection is performed by the single detector 10 has been described, but a structure in which the on / off switch and the detectors 10 and 10 are connected to the hot water leak detection nets 8A and 8B, respectively, is also possible. good.

[0024]

As described above, according to the molten metal leak detecting device of the induction melting furnace according to the present invention, when the molten metal leak detecting device operates, it is possible to easily determine whether it is due to zinc or molten metal due to molten metal. As a result, unnecessary furnace replacement work can be eliminated and efficient and safe operation can be performed.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of an induction melting furnace equipped with a molten metal leak detection device according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view showing a main part of FIG. 1;

FIG. 3 is an explanatory diagram showing a change state of a pointer of the detector.

FIG. 4 is a vertical sectional view of an induction melting furnace equipped with a conventional molten metal leak detection device.

[Description of sign]

 1 Molten metal holding lining 2 Melting chamber 3 Coil holding lining 4 Heating coil 5 Return path iron core 6 Furnace frame 7 Needle-shaped electrode 8A Hot water leak detection network 8B Hot water leak detection network 9 DC power supply 10 Detector 11 Recorder 12 Melt 13 switching Vessel 14 interface 16 pointer

Claims (2)

[Claims] 1. A boundary surface between the molten metal holding lining and the coil holding lining of an induction melting furnace in which a coil holding lining is provided outside a molten metal holding lining forming a melting chamber, and a heating coil is further wound outside the molten metal holding lining. A molten metal leak detection device for an induction melting furnace, characterized in that molten metal leak detection networks are arranged on both sides of the sandwich, and these molten metal leak detection networks are connected to a detector. 2. When the molten metal leak detection net arranged on the molten metal holding lining side detects a molten metal leak state, the position of the pointer of the detector connected to the molten metal leak detection net arranged on the coil holding lining side starts warning. The molten metal leak detection device for an induction melting furnace according to claim 1, wherein the molten metal leak detection device is used as a starting point.