JPH09243470A - Method for measuring level of molten metal in molten metal container and apparatus therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately measure a level position of a molten metal by laying an optical fiber in a molten metal container having a refractory lining, and obtaining the level position based on a temperature distribution pattern measured by an optical fiber temperature distribution sensor. SOLUTION: The inner wall of a main body 2 of a burnt ash-melting furnace 1 comprises lined refractories 5a-5c and a bottom refractory 6. First, wastes are thrown into the furnace 1 from waste throw-in openings 4. An alternating current voltage is applied to electrodes 9 from a power source device 23 to melt the wastes. A burnt ash layer P, a molten slag layer S and a molten metal layer M are formed. In the meantime, a light signal modulated with a pseudo random signal is projected to an optical fiber switched by an optical fiber channel selector 21, and an inert gas such as N2 or the like is supplied to optical fiber tubes 13 from an inert gas feed device 20. A back scattering light from an inflection point of the optical fiber generated by a temperature change in the furnace is switched by the selector 21, sent to an optical fiber temperature distribution sensor 22, converted to electric signals and processed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molten metal level measuring method and apparatus for a molten metal container lined with a refractory material, for example, incinerator ash melting for melting waste incinerated ash and waste incinerated ash such as sewage sludge. The present invention relates to a molten metal level measuring method and apparatus for measuring the position of a molten slag surface in a furnace.

[0002]

2. Description of the Related Art For example, since wastes such as incinerated ash of municipal waste and incinerated ash of sewage sludge contain various inorganic and organic substances, if they are buried in the ground as they are, serious secondary pollution will occur. cause. Therefore, in recent years, incinerator ash melting furnaces have been used to detoxify such waste.

This incinerator ash melting furnace resistance-heats the waste introduced by energizing between the electrodes charged inside, and most of the waste is made into molten slag which is a glassy melt, and the remaining The thing is made into molten metal which is a metal, and both are separated,
It is designed to be discharged to the outside. Then, in order to operate the melting furnace efficiently, it is desirable to sequentially charge a predetermined amount of waste into the melting furnace, continuously take out a large amount of molten slag, and intermittently take out a small amount of molten metal. . The condition in this case is that the height difference between the slag surface of the molten slag and the slag outlet is always constant, the slag surface in the furnace is always kept within a predetermined range, and the waste is efficiently In order to melt, the tip of the electrode needs to be located at a certain depth from the slag surface.

By the way, since the upper portion of this melting furnace is hermetically closed, the position of the slag surface in the furnace cannot be known. Further, since the ratio of organic matter and inorganic matter contained in the waste is not known, the position of the molten slag surface fluctuates even when a predetermined amount of waste is put into the melting furnace, and when the position of the molten slag surface is too low. The slag extraction port may be clogged, or molten metal may be mixed with the molten slag that is taken out and the slag cannot be reused. On the other hand, when the position of the molten slag surface is too high, the molten slag may overflow from the melting furnace.

Further, since the position of the molten metal surface also fluctuates, it was not possible to judge when the molten metal should be taken out. Furthermore, it is not possible to know whether the tip of the electrode is located at a certain depth from the molten slag surface.If the tip of the electrode is not located at a certain depth from the molten slag surface, discard it. It cannot melt things efficiently. Therefore, in order to avoid such a situation, it has been required to know the position of the molten slag surface in the melting furnace.

Conventionally, in an incinerator ash melting furnace whose upper part is hermetically sealed, there are the following methods or devices for measuring the molten metal surface depth of the melting furnace for knowing the position of the molten slag surface in the furnace. It was

Method for measuring molten metal depth: The temperature of the molten slag in the furnace was detected by a thermocouple with a protective tube inserted into the furnace from the furnace lid, and the position of the molten slag surface was known based on this temperature. This is a method of directly measuring the temperature of the molten slag surface (prior art 1).

Melt depth measuring device: JP-A-6-19420
This apparatus is disclosed in Japanese Patent Publication No. 8 and a wire feeding device for feeding a metal wire from a furnace top to a terminal plate provided on the furnace bottom at a predetermined feeding amount, and a wire feeding device. The encoder that measures the feed amount of the wire sent out by, the power supply device that supplies the voltage to the wire and the terminal plate, the means that measures the voltage between the wire and the terminal plate or the current flowing through the wire, and the encoder It is provided with a calculation means for calculating the positions of the molten slag surface and the molten metal surface from the furnace top based on the measured wire feed amount and voltage change or current change (prior art 2).

In the prior art 2, a wire feeding device feeds a metal wire to a terminal plate provided from the furnace top to the furnace bottom of the melting furnace at a predetermined feeding amount and is fed by an encoder. While measuring the wire feed amount, a predetermined voltage is applied between the wire and the terminal plate by the power supply during wire feeding, and the voltage change between the wire and the terminal plate during wire feeding is measured by a voltmeter. Or the change in the current flowing in the wire with an ammeter, the feed amount of the wire measured by the encoder by the calculation means, and the position of the molten slag surface and the metal surface from the furnace top based on the voltage change or the current change. Is calculated, and the positions of the molten slag surface and the metal surface in the melting furnace are detected based on the calculation result.

Japanese Unexamined Patent Publication No. 4-351254 discloses a mold level measuring device in continuous casting. This device embeds or adheres an optical fiber to the mold wall surface or surface, and connects an optical fiber temperature distribution meter (pulse laser projector and reflection intensity analyzer to one end of this optical fiber, The scattered light intensity and the elapsed time are converted into the temperature at each scattering position, and a device that outputs temperature information in the length direction of the optical fiber to a CRT or the like is connected, and the temperature is changed. The point is determined as the molten steel level (prior art 3).

[0011]

The method of the prior art 1 is as follows.
Since the temperature of the molten slag at an extremely high temperature (about 1500 ° C) is repeatedly measured, the life of the protective tube and thermocouple is short and they are treated as consumables, and they have to be replaced frequently, so the replacement work is troublesome. Not only there, but the running cost increases.

In the apparatus of the prior art 2, it is extremely difficult to accurately feed the metal wire in the vertical direction to the furnace bottom, and bending is likely to occur. Further, since the upper part of the melting furnace is hermetically closed, it is not possible to confirm the state of the wire inside the furnace, which may result in a large measurement error. In addition, since the measurement wire can be used only once, it is necessary to cut the wire and feed a new wire for each measurement. Further, dangerous work such as replacement of the wire drum must be performed on the melting furnace.

Further, in the prior art 3, the mold is usually made of a copper plate having a thickness of several tens of mm, and the mold is cooled by a refrigerant to remove heat from the molten steel to be solidified to form an outer shell and kept at a low temperature. In addition, the measurement of a temperature of up to about 250 ° C. is intended because of the heat resistance of the optical fiber itself. Therefore, even if it is embedded in a refractory consisting of 3 to 4 layers having a total thickness of several 100 mm, such as an incinerator ash melting furnace, the temperature difference becomes extremely small and the positional resolution of the optical fiber is poor, so that the inside of the molten metal container When the molten metal level is measured, the accuracy is low, and the molten metal level cannot be actually measured.

The present invention has been made in order to solve the above-mentioned problems. By laying an optical fiber in a refractory material of a molten metal container lined with a refractory material, the position of the molten metal level in the molten metal container is determined. It is an object of the present invention to provide a method and an apparatus for measuring a molten metal level in a molten metal container, which enables accurate measurement.

[0015]

[Means for Solving the Problems]

(1) The molten metal level measuring method of the molten metal container according to the present invention is
An optical fiber is laid in a molten metal container lined with a refractory material in the direction in which the molten metal level changes, over at least the changing range, and an optical fiber temperature distribution meter that uses an optical signal modulated with a pseudo-random signal The temperature distribution of the fiber is measured, and the position of the molten metal level is determined based on this temperature distribution pattern.

(2) Further, in the method for measuring the molten metal level of the molten metal container of the above (1), both ends of an optical fiber laid in a refractory lining are connected to an optical fiber channel selector and an optical fiber temperature distribution meter is used. The temperature distribution of the optical fiber was measured from both directions, and the position measurement error of the molten metal level was corrected. (3) An M-sequence signal is used as the pseudo-random signal in (1) and (2) above.

(4) The molten metal level measuring apparatus for a molten metal container according to the present invention comprises a plurality of conduits installed in a refractory of a molten metal container lined with a refractory material in a direction in which the molten metal level changes. Optical fiber laid inside each,
An optical fiber channel selector to which this optical fiber is connected, and an optical fiber temperature distribution meter for processing an optical signal from the optical fiber channel selector are provided.

(5) The conduit of (4) above was constructed by coating a stainless steel tube with an alumina tube. (6) In the above (4) or (5), the optical fiber is N
An optical fiber tube inserted through a metal tube made of i alloy was laid in the conduit, and an inert gas supply device for supplying an inert gas to the optical fiber tube was provided.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. FIG. 1 is a schematic explanatory view of an incinerator ash melting furnace in which the first embodiment of the present invention is implemented. In the figure, 1 is an incinerator ash melting furnace, 2 is a furnace body thereof, 3 is a lid for closing an upper opening of the furnace body 2, and 4 is a waste inlet provided in the lid 3. As shown in FIG. 2, the inner wall of the furnace body 2 is lined with lined refractory materials 5a, 5b, 5c which are arranged in a plurality of rows in the radial direction, and the bottom portion is a bottom refractory material 6 as shown in FIG. It is composed of. Reference numeral 7 is a slag vent hole provided in the furnace wall of the furnace main body 2, and 8 is a metal vent hole provided in the furnace wall near the furnace bottom.

Reference numeral 9 denotes a plurality of electrodes (only two of which are shown in the figure) installed so that they can move up and down in the furnace body 2 through the lid 3 and reach the bottom of the furnace near the bottom. Then, an AC voltage is applied from the power supply device 23.

Reference numeral 10 denotes a lid 3 and a refractory 5 lining the furnace body 2.
a to 5c, a boundary portion of a position not exceeding 1000 ° C. even at the time of wear and close to the molten slag (for example, between the lining refractory materials 5a and 5b or between 5b and 5c), and a furnace bottom refractory material Direction of changing molten slag level through 6
It is therefore a vertically installed conduit. Although only two conduits 10 are shown in the drawing, a plurality of conduits 10 are installed in the circumferential direction. As shown in the cross section of FIG. 3, the conduit 10 includes a stainless tube 11 and an alumina tube 12 that is coated on the outer periphery of the conduit 10 to prevent carburization of carbon contained in the refractory at high temperature into the stainless tube 11. It consists of

Reference numeral 13 denotes an optical fiber tube (Fiber In Metallic) in which an optical fiber 15 coated with a polyimide resin is inserted into a metal tube (Hastelloy tube) 14 made of Ni alloy.
Tube), each of which is laid through the inside of the conduit 10 and has one end connected to an optical fiber channel selector via an inert gas supply device described later and the other end fixed to the lower end of the conduit 10. . The lower part of the optical fiber tube 13 may be located in the range of slag level change in the furnace.

Reference numeral 20 denotes an inert gas supply device for supplying an inert gas such as N ₂ into the optical fiber tube 13, which is a pressure regulator, a flow meter, a dust filter, a moisture removal filter,
It is equipped with valves. 21 switches a plurality of optical fibers 15 to transmit an optical signal from an optical fiber temperature distribution meter, which will be described later, to the specific optical fiber, and the specific optical fiber 1
5 is an optical fiber channel selector that sends the backscattered light from 5 to the optical fiber temperature distribution meter.

Reference numeral 22 denotes an optical fiber temperature distribution meter, which is a projector for projecting an optical signal modulated by a pseudo-random signal (for example, an M series signal) to each optical fiber 15, and each optical fiber 15.
Receiver for receiving the backscattered light from the inflection point, an optical / electrical converter for converting the backscattered light received by the light receiver into an electric signal, and measuring the temperature distribution of the optical fiber 15 by processing the electric signal. A signal processor (including a CRT) is provided. In addition, you may provide some of these each component separately.

In the present embodiment configured as described above, in order to lay the optical fiber 15, first, the refractory 5a adjacent to the lid 3 and the refractory 5a to 5c in the radial direction is adjacent to the refractory 5a.
And 5b or 5b and 5c and the furnace bottom refractory 6 are penetrated, and both ends are projected from the upper surface of the lid 3 and the bottom surface of the furnace bottom refractory 5, and the conduit 10 is installed in the vertical direction. To do.
Then, the optical fiber tubes 13 with the optical fibers 15 inserted therein are inserted and laid in the conduits 10, respectively, and the tip end portions thereof are fixed to the end portions of the conduit tube 10, and the other end portion thereof is provided with the inert gas supply device 20. It is connected to the optical fiber channel selector 21 via the optical fiber channel selector 21. The output side of the optical fiber channel selector 21 is connected to the optical fiber temperature distribution meter 22 by one optical fiber tube 13.

Next, an example of the operation of this embodiment configured as described above will be described. First, the waste is put into the furnace through the waste input port 4 provided in the lid 3, and the power supply 23
AC voltage is applied to the electrode 9 from. Thereby, the electrode 9
The waste is melted by the resistance heating generated in the above, and becomes a molten slag and molten metal, and the incinerated ash layer P, the molten slag layer S, and the molten metal layer M are formed from above. In addition, incineration ash layer P
Has a smaller thickness than the molten slag layer S and the molten metal layer M, but plays an adiabatic role with respect to the upper space in the furnace.

At this time, the temperature in the furnace is as low as about 600 ° C. on the upper surface of the incinerated ash layer P, and the molten slag layer S and the molten metal layer M below the incinerated ash layer P are 150.
The temperature is higher than 0 ° C. Under this influence, a similar temperature distribution is generated at the position of the optical fiber 15, but this temperature distribution changes in accordance with the fluctuation of the slag level S _L.

On the other hand, an optical signal modulated by a pseudo random signal is projected onto the optical fiber 15 switched by the optical fiber channel sector 21, and each optical fiber tube 1
An inert gas such as N ₂ is fed from the inert gas supply device 20 into the inside of the chamber 3, and is discharged from the tip thereof. Then, the backscattered light from the inflection point of the optical fiber 15 generated according to the change in the temperature in the furnace is switched by the optical fiber channel selector 21 and sent to the optical fiber temperature distribution meter 22 and converted into an electric signal. It is processed.

FIG. 4 shows an example of the temperature distribution in the furnace during melting of the waste measured by the optical fiber 15 in the incinerator ash melting furnace as described above. 4 (A) is a temperature distribution diagram in the furnace before slag removal, and FIG. 4 (B) is a furnace temperature distribution diagram after slag removal. Further, in FIG. 4, the vertical axis represents the temperature inside the furnace, and the horizontal axis represents the length of the optical fiber 15 from the furnace upper part to the furnace lower part.

In FIG. 4 (A), H ₂ to H ₃ are temperature rising portions from the lower surface of the lid 3 to the melting level of the incineration ash layer P, and most of the temperature rising distance during this time is the optical fiber. This is due to the response distance of the temperature distribution meter 22.
In other words, in this temperature distribution, the temperature rise has stopped for a while between H ₃ and H ₄ , but the actual width of this temperature distribution is
It is considered to be wide by the response distance.

In the actual temperature distribution, it is considered that the temperature rises from the upper part to the lower part around the position of the slag level S _L of the molten slag layer S, so that it is almost in the middle of H ₄ and H ₅ (the arrow). slag level S _L ). From H ₅ to H ₆ is the molten slag layer S molten metal layer M, a temperature stabilizer. H ₆ is the upper surface position of the furnace bottom refractory 6, and thereafter, since it enters the furnace bottom refractory 6, the temperature starts to drop.

FIG. 4 (B) shows the temperature distribution in the state where the slag is removed and the slag level S _L is lowered. The H ₄ position moves to the right side of the figure, that is, the furnace bottom side with the slag removal. However, the position of slag level S _L (arrow a ₁ ) is h
You can see that it is moving downward. And furthermore,
It can be seen that the distance from H ₅ to H ₆ becomes shorter and the depth of the molten slag layer S becomes shallower. However, the temperature distribution from H ₃ to H ₄ are different from the case of FIG. 4 (A), even after the slag level S _L is lowered, because the lowered top of the slag level S _L temperature is high, the H ₃ H _The temperature has risen over ₄ .

(Example) At the boundary between the refractory linings 5a and 5b of the incineration ash melting furnace 1 shown in FIGS. 1 and 2, a conduit 10 is installed vertically vertically, and an optical fiber tube 13 is installed therein. Was installed and the temperature distribution in the furnace was continuously measured. The specifications of the optical fiber temperature distribution meter, the optical fiber tube and the conduit were as follows. (1) Optical fiber temperature distribution meter Temperature accuracy ± 5% Measurement temperature 0 to 1000 ° C Response distance 400mm Distance resolution 20mm Response time 200 seconds (200 times average) Measurement distance 240m Projection method Modulated by M-sequence pseudo-random signal (2) Optical fiber tube and conduit Optical fiber material Quartz glass Optical fiber coated with polyimide Core / clad diameter 200/250 μm Multimode metal tube Material Ni alloy (Hastelloy) Inner / Outer diameter 1.8 / 2.2 mm Conduit material Stainless steel Inner / Outer Diameter 8 / 10mm Protective tube Material Alumina inert gas N ₂ gas

From the above, when the temperature distribution inside the furnace before the start of slag removal and the temperature distribution inside the furnace after the completion of slag removal were measured, a temperature distribution pattern as shown in FIG. 5 was obtained. 5 (A) shows the temperature distribution in the furnace before slag removal, and FIG. 5 (B) shows the temperature distribution in the furnace after slag removal. As is clear from the figure, after the slag removal is completed, the slag level drops by h from point a to point a ₁ .

Embodiment 2. FIG. 6 is a schematic explanatory view of the second embodiment of the present invention. The same parts as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. In the present embodiment, both ends of the optical fiber 15 laid in each conduit 10 provided at the boundaries of the refractory linings 5a to 5c are connected to the optical fiber channel selector 21 via the inert gas supply device 20, respectively. It is connected. With this configuration, by switching the optical fiber channel selector 21, the optical signal is alternately projected from both ends of the optical fiber 15, and the backscattered light from both ends of the optical fiber 15 is emitted. By measuring, the temperature distribution in the furnace can be measured more accurately.

FIG. 7 shows H ₄ in FIG. 4 when the temperature in the furnace is measured by alternately projecting light from both ends of the optical fiber 15.
₃ shows the temperature distribution in the region from H ₅ to H ₅ . In FIG. 7, the one-dot chain line A is the result of measuring the temperature distribution in the furnace by projecting light from the furnace upper side toward the furnace bottom, and the one-dot chain line B is projecting light from the opposite direction and measuring the temperature in the furnace. It is the result of measuring the distribution. Also,
The solid line C is the expected actual temperature distribution line. That is,
Strictly speaking, it can be seen that the intersection H between the solid line C connecting H ₄ A and H ₅ B and the broken line D connecting H ₄ B and H ₅ A is a position close to the actual slag level S _L.

As described above, according to the present invention, the optical fiber temperature distribution meter in which the optical signal is modulated by the M-sequence pseudo-random signal is capable of high temperature measurement, and the molten slag in the refractory lining the furnace body is as much as possible. , That is, the conduit is provided at a position where the temperature inside the furnace is relatively well reflected in the refractory, and the optical fiber tube is laid inside this conduit. The temperature distribution in the furnace formed by the temperature of the molten slag can be measured with high sensitivity in the refractory lining, and the position of the molten slag level can be determined by analyzing the changes in the gradient of this temperature distribution pattern and changes over time. Can be measured.

Further, the optical fiber temperature distribution meter using the optical signal modulated by the M-sequence pseudo-random signal has a response distance which is 3 to 10 times more excellent than the conventional one, and the sampling data pitch is 50 times the conventional one. Since it is 100 times or more excellent, the actual temperature distribution in the furnace can be traced more accurately, and therefore, the position of the molten slag level can be accurately measured.

Further, since the backscattered light of a plurality of optical fibers can be continuously measured by the optical fiber channel selector, the position of the molten slag level in the circumferential direction of the furnace can be accurately determined by simply increasing the number of optical fibers. Can be grasped. Also, by connecting both ends of each optical fiber to the optical fiber channel selector, it is possible to measure the temperature distribution in the furnace from both ends of the optical fiber,
By correcting the detection error of the slag level due to the response distance of the optical fiber temperature distribution meter, the position of the molten slag level can be measured with higher accuracy.

Further, since the metal tube made of Ni alloy having the optical fiber inserted therein is laid in the conduit installed in the refractory lining of the furnace body to have a double tube structure, for example, the optical fiber If the optical fiber is optically deteriorated or mechanically broken, it can be easily replaced by pulling out the optical fiber together with the metal tube from the conduit and laying a new optical fiber tube. Further, by feeding an inert gas having a low reactivity with the optical fiber into the metal tube, deterioration of the optical fiber can be prevented.

In the above description, the case where the present invention was carried out to measure the molten slag level of the incinerator ash melting furnace was shown, but the present invention is not limited to this, and the level of the molten metal in another molten metal container can be measured. It can also be performed for measurements.

[0042]

【The invention's effect】

(1) The molten metal level measuring method of the molten metal container according to the present invention is
Optical fiber temperature distribution using an optical signal modulated by a pseudo-random signal by laying an optical fiber in the refractory of a molten metal container lined with a refractory in the direction in which the molten metal level changes, over at least the range The temperature distribution of the optical fiber was measured with a meter, and the position of the molten metal level was determined based on this temperature distribution pattern. The position of the molten metal level can be accurately measured by measuring the temperature in an object with high sensitivity and analyzing the temperature distribution pattern.

(2) In the method for measuring the molten metal level of the molten metal container of the above (1), both ends of an optical fiber laid in a refractory lining are connected to an optical fiber channel selector and an optical fiber temperature distribution meter is used. Since the temperature distribution of the optical fiber is measured from both directions and the position measurement error of the molten metal level is corrected, the molten metal level position can be measured with higher accuracy.

(3) Since the M-sequence signal is used as the pseudo-random signal of (1) and (2) above, the response distance and sampling data pitch are greatly improved, and the temperature distribution in the furnace is traced more accurately. Therefore, the position of the molten metal level can be accurately measured.

(4) Further, the molten metal level measuring apparatus for a molten metal container according to the present invention includes a plurality of conduits installed in a refractory material of a molten metal container lined with a refractory material in a direction in which the molten metal level changes. Since the optical fiber laid in each of the conduits, the optical fiber channel selector to which the optical fiber is connected, and the optical fiber temperature distribution meter for processing the optical signal from the optical fiber channel selector are provided, the molten metal in the molten metal container is provided. The optical fiber can be laid at a position close to the position of the molten metal, which allows the temperature distribution in the molten metal container to be measured with high sensitivity and the temperature distribution pattern to be analyzed by an optical fiber temperature distribution meter to accurately determine the position of the molten metal level. Can be measured.

(5) Since the conduit of (4) above is constructed by coating the stainless tube with the alumina tube, carburization of the stainless tube can be prevented and the life can be extended.

(6) An optical fiber tube in which the optical fiber of the above (4) or (5) is inserted into a metal tube made of Ni alloy is laid in the conduit, and an inert gas is supplied from the inert gas supply device into the optical fiber tube. Since the gas is supplied, it is possible to measure high temperature and prevent deterioration of the optical fiber.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of an incinerator ash melting furnace in which a first embodiment of the present invention is implemented.

FIG. 2 is a sectional view taken along the line AA of the furnace body in FIG.

FIG. 3 is a cross-sectional view of a conduit and a fiber optic tube.

FIG. 4 is a diagram showing a temperature distribution pattern in the incinerator ash melting furnace measured by the present invention.

FIG. 5 is a temperature distribution diagram in the incinerator ash melting furnace measured according to an example of the present invention.

FIG. 6 is a schematic explanatory view of a second embodiment of the present invention.

FIG. 7 is a diagram showing a part of the temperature distribution in the incinerator ash melting furnace measured in the second embodiment.

[Explanation of symbols]

 1 Incinerator Ash Melting Furnace 2 Furnace Main Body 3 Lid 4 Waste Input Port 5a-5c Lining Refractory 6 Furnace Bottom Refractory 7 Slag Extraction Hole 8 Metal Extraction Hole 9 Electrode 10 Conduit 11 Stainless Steel Tube 12 Alumina Tube 13 Optical Fiber Tube 14 Metal tube 15 Optical fiber 20 Inert gas supply device 21 Optical fiber channel selector 22 Optical fiber temperature distribution meter 23 Power supply device

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI technical display location G01K 13/00 G01K 13/00 (72) Inventor Tetsuo Akashi 1-2-1, Marunouchi, Chiyoda-ku, Tokyo No. Nihon Steel Pipe Co., Ltd. (72) Inventor Tadashi Miyagawa 1-2 1-2 Marunouchi, Chiyoda-ku, Tokyo Nihon Steel Pipe Co., Ltd.

Claims (6)

[Claims] 1. An optical fiber is laid in the refractory of a molten metal container lined with a refractory in a direction in which the level of the molten metal changes at least over the range of change, and an optical signal modulated by a pseudo-random signal is generated. A molten metal level measuring method for a molten metal container, characterized in that the temperature distribution of the optical fiber is measured by an optical fiber temperature distribution meter used and the molten metal level is obtained based on the temperature distribution pattern. 2. A position measurement of a molten metal level by connecting both ends of an optical fiber laid in a refractory lining to an optical fiber channel selector and measuring the temperature distribution of the optical fiber from both directions by an optical fiber temperature distribution meter. The method for measuring a melt level of a melt container according to claim 1, wherein an error is corrected. 3. The molten metal level measuring method for a molten metal container according to claim 1, wherein the pseudo random signal is an M-sequence signal. 4. A plurality of conduits installed in a direction in which the molten metal level changes in the refractory of a molten metal container lined with a refractory, optical fibers respectively laid in these conduits, and the optical fibers are connected. A molten metal level measuring device for a molten metal container, comprising: an optical fiber channel selector; and an optical fiber temperature distribution meter for processing an optical signal from the optical fiber channel selector. 5. The molten metal level measuring device for a molten metal container according to claim 4, wherein the conduit is formed by coating a stainless steel tube with an alumina tube. 6. An optical fiber tube formed by inserting an optical fiber into a metal tube made of Ni alloy is laid in a conduit, and
The molten metal level measuring device according to claim 4 or 5, further comprising an inert gas supply device for supplying an inert gas to the optical fiber tube.