JPH05142059A - Thermocouple-type thermometer for measuring temperature of molten metal - Google Patents

Abstract

PURPOSE:To detect the temperature of a molten steel highly accurately and quickly. CONSTITUTION:An inner insulating pipe 2 formed of alumina of high purity is fitted outside an iron rod 1. The total length of the insulating pipe 2 is shorter than the iron rod 1. A molybdenum pipe 3 is further fitted outside the inner insulating pipe 2, and an outer insulating pipe 4 of alumina of high purity which is shorter than the molybdenum pipe 3 is fitted outside the molybdenum pipe 3. Accordingly, a thermocouple type thermometer is obtained. When the thermocouple type thermometer of this structure is dipped in a molten steel, the dipped part projecting from the iron rod 1 and the insulating pipes 2, 4 of the molybdenum pipe 3 is quickly heated by the molten metal, thereby constituting a thermocouple by the iron rod 1, molten steel and molybdenum pipe 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermocouple type thermometer,
More specifically, the present invention relates to a thermocouple type thermometer for measuring the temperature of molten metal, which continuously measures the temperature of molten steel.

[0002]

2. Description of the Related Art The temperature of molten steel poured into a ladle or a tundish for continuous casting must be controlled,
A thermocouple type thermometer is often used for the temperature control. Such a thermocouple-type thermometer generally has a structure in which a thermocouple for high temperature is incorporated in a refractory insulating tube that can be immersed in molten steel. However, since the thermocouple thermometer having such a configuration is protected by an insulating tube, it requires a response time of, for example, several tens of seconds to 1 minute, and is not always sufficient for controlling the temperature of molten steel. ..

By the way, there is a structure in which an insulating material for protecting the temperature measuring unit is removed and the structure is exposed to speed up the response time of the temperature measuring. This is to utilize molten steel as one of the metals, more specifically, the tip of molybdenum is immersed in molten steel, and between the other end of this molybdenum and the roll that rolls into the slab through the molten steel. The circuit is configured to detect thermoelectromotive force.

[0004]

The thermocouple type thermometer is considered to be useful as such, but it still has the following problems from the viewpoint of temperature detection accuracy. That is, scale and flux adhere to the surface of the cast slab, and in addition to having electrical insulation, they have a contact resistance and a contact potential difference, so that they have 20 to 20 mm.
There is a drawback that a weak thermoelectromotive force of 30 mV cannot be accurately detected.

Further, a temperature difference (about 200 to 300 ° C.) always occurs between the support bearing and the fixed portion of the roll,
Since this constitutes a local thermocouple, parasitic thermoelectromotive force is generated, which adversely affects the measurement accuracy. In addition, the molybdenum wire soaked in molten steel is in contact with all the molten steel, so even if the average temperature of the immersion length can be measured, the original point temperature cannot be measured. There is also a drawback.

Therefore, an object of the present invention is to provide a thermocouple type thermometer for measuring the temperature of a molten metal which is compact and excellent in temperature measuring accuracy by forming a temperature measuring point only at a portion to be measured.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems. Therefore, the structure of a thermocouple type thermometer for measuring a molten metal temperature according to claim 1 of the present invention is as follows. In a thermocouple type thermometer for measuring a molten metal temperature composed of a combination of two types of thermocouple metals, an insulating pipe made of a non-conductive refractory is interposed between the two types of metals and is not externally provided except for one end side. It is characterized in that an insulating tube made of a conductive refractory material is externally fitted.

A thermocouple type thermometer for measuring a molten metal temperature according to claim 2 of the present invention is a thermocouple type thermometer for measuring a molten metal temperature, comprising a combination of two kinds of thermocouple metals. An insulating tube made of a non-conductive refractory material is externally fitted to each of the two kinds of metal, and one end side of each of these metals is opened.

[0009]

According to the thermocouple-type thermometer according to the first aspect of the present invention, the nonconductive fireproof is provided outside the one end side through the insulating tube made of the nonconductive refractory between the two kinds of metals for the thermocouple. Since an insulating tube made of material is fitted on the outside, there is electrical insulation between the two types of metal except the one end side, and when the one end side is immersed in the molten metal, the temperature of the immersion part rises. Thermoelectromotive force is generated at one end thereof.

Further, according to the thermocouple type thermometer of the second aspect, an insulating tube made of a non-conductive refractory is fitted onto each of the two types of metals for the thermocouple, and one end of each of these metals is fitted. Since the side is open, there is electrical insulation between the two types of metal except the open part, and when the open part is immersed in molten metal, a circuit is formed between the molten metal and these parts. To be done.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of a thermocouple type thermometer for measuring a molten metal temperature according to the present invention will be described below with reference to FIG.
2 and FIG. 2 which is an explanatory diagram of the insulation resistance change with respect to the temperature change of the inner and outer insulation pipes.

That is, reference numeral 1 shown in FIG. 1 is an iron rod having an outer diameter of 6 mm, and an internal insulating tube 2 made of a high-purity alumina material is externally fitted to the iron rod 1. A cylindrical molybdenum tube 3 having an inner diameter of 10 mm and an outer diameter of 20 mm is fitted onto the inner insulating tube 2, and the molybdenum tube 3 is made of a high-purity alumina material having a shorter overall length.
Is fitted on the outside. Of course, conversely to the above, even if iron is made tubular and molybdenum is made rod-shaped, the same effect can be obtained.

The operation mode of the thermocouple type thermometer having the above structure will be described below. If one end on the right side in FIG. 1 is immersed in a molten metal, for example, molten steel, the temperature of the immersion site rises rapidly, and Since molten steel intervenes between the tip surface of the iron rod 1 and the protruding portion of the molybdenum tube 3 from the outer insulating tube 4, an electric circuit is formed and thermoelectromotive force is generated.
The potential difference is detected from the other end on the left side in the figure.

As is well understood from FIG. 1, since the range of the protruding portion from the outer insulating tube 4 is narrow,
Compared with a conventional molybdenum-immersion type thermometer, it is possible to measure the temperature of molten steel in a narrower range, that is, in a range closer to a point, at a high response speed. Of course, the protruding portion of the iron rod 1 is melted and gradually consumed depending on the temperature of the molten steel, but the tip of the iron rod 1 and the molybdenum pipe 3 are surely immersed in the molten steel, so that it is particularly important when measuring the temperature of the molten steel. It does not cause any problems.

By the way, the concern about the temperature measurement accuracy is the deterioration of the insulation resistance of the internal insulation pipe 2 between the iron rod 1 and the molybdenum pipe 3 at high temperature, and the shunt error occurs due to the deterioration of the insulation resistance. is there. Therefore, the change in the insulation resistance of the inner insulating tube 2 with respect to the change in temperature was examined, and it was as shown in FIG.

FIG. 2 shows the insulation resistance of the outer insulation pipe by the circle and the solid line, and the insulation resistance of the inner insulation pipe by the circle and the solid line. Rapidly decreases with increasing temperature, and exhibits the lowest insulation resistance value at around 1100 ° C., but the insulation resistance value increases with increasing temperature, and remains above about 40 KΩ at 1300 ° C. or higher. By the way, it is well understood that the generated thermoelectromotive force is several tens of mV, and thus the error due to the enchantment error can be ignored.

Next, the second embodiment will be described with reference to FIG. 3 which is an explanatory view of its structure, and the combined heat of each of iron and molybdenum and platinum with respect to temperature change (a Type-R reference thermocouple is used for temperature measurement). The electromotive force relationship diagram of FIG. 4 and the thermoelectromotive force explanatory diagram of the thermocouple type thermometer of this embodiment shown in FIG. 5 are the same as those of the first embodiment except for differences in configuration. Those having the same function will be described with the same reference numerals.

That is, the inner insulating tube 2 made of high-purity alumina is externally fitted to the iron rod 1, these are fitted to the bottomed molybdenum tube 3 fitted to the outer insulating tube 4, and the molybdenum tube 3 is One end of the iron rod 1 is in contact with the bottom portion 3a.

Therefore, when the bottomed side of the molybdenum tube 3 is immersed in molten steel, a temperature measuring point is formed at the contact portion between the bottom portion 3a of the molybdenum tube 3 and the iron rod 1. Therefore, the operation and effect of this embodiment The effect is almost the same as that of the first embodiment.

However, even though the temperature measuring response is slightly inferior to that of the thermometer according to the first embodiment, even if the iron rod 1 is melted, it is still in the molten steel metal as in the first embodiment. Since it is not mixed and consumed, it has an advantage that it is superior in terms of life and the economy is greatly improved.

By the way, the thermoelectromotive force of platinum and molybdenum is
Fig. 4 shows the thermoelectromotive force of platinum and iron by the mark and the solid line, and Fig. 4 shows the thermoelectromotive force of the platinum and iron by the solid line, and Fig. 5 shows the thermoelectromotive force of the thermocouple type thermometer having the above configuration. Becomes As you can see from both these figures,
It was also confirmed that the value obtained by subtracting the thermoelectromotive force shown by □ from the thermoelectromotive force shown by ○ in FIG. 4 is in good agreement with the thermoelectromotive force shown in FIG. 5 and is highly accurate and reproducible. did.

In the following, the third embodiment will be described with the same reference numerals while referring to FIG. 6 which is a structural explanatory view showing the state of being immersed in molten steel w. The molybdenum rod 3b and the iron rod 1 are each fitted with the outer insulating tube 4, and one end side of each of the outer insulating tubes 4 is opened to form a separation structure. By the way, in the case where the molybdenum rod 3b and the iron rod 1 are laterally arranged across the insulating pipes 4 and 4 which are fitted on the outer surface, the thermocouple type thermometer having this configuration is integrally coupled. It is a connecting member. Therefore, these two rods 1, 3
When the open portion side of b is immersed in the molten steel w, an electric circuit is formed through the molten steel w, and this embodiment has the same effect as the first embodiment.

In the above description, an example in which iron and molybdenum are combined as the two types of thermocouple metals has been described, but, for example, a combination of tungsten and molybdenum or a known combination may be used. The scope of the technical idea of the present invention is not limited by the above embodiments.

[0024]

As described in detail above, according to the thermocouple type thermometer according to the first aspect of the invention, one end of the thermocouple type thermometer is provided between the two kinds of metal for the thermocouple via the insulating tube made of a non-conductive refractory. Since an insulating tube made of a non-conductive refractory is fitted on the outside except the side, when one end side is immersed in molten metal, the temperature of the immersion part rises and thermoelectromotive force is generated at that one end side. Further, according to the thermocouple type thermometer according to claim 2, an insulating tube made of a non-conductive refractory is externally fitted to each of the two types of metals for the thermocouple,
Since one end side of each of these metals is open, when the open part side is immersed in the molten metal, a circuit is formed between the molten metal and these parts. 20-30 without worrying about contact potential difference
It is possible to accurately detect a weak thermoelectromotive force of mV.

Further, since the outermost side is protected by the insulating pipe and only the protruding portion thereof comes into contact with the molten metal, the original point temperature can be measured. The structure of the thermocouple type thermometer is also extremely simple, and has a very great effect on the improvement of the economical efficiency and the improvement of the temperature measurement accuracy due to its compactness.

[Brief description of drawings]

FIG. 1 is a structural explanatory view of a thermocouple type thermometer for measuring a molten metal temperature according to a first embodiment.

FIG. 2 is an explanatory diagram of a change in insulation resistance with respect to a temperature of an internal insulating tube interposed between two kinds of metals.

FIG. 3 is a structural explanatory view of a thermocouple type thermometer for measuring molten metal temperature according to a second embodiment.

FIG. 4 is a combined thermoelectromotive force relationship diagram of iron, molybdenum, and platinum with respect to temperature change.

FIG. 5 is an explanatory diagram of thermoelectromotive force of the thermocouple type thermometer according to the second embodiment.

FIG. 6 is a structural explanatory view of a separate type thermocouple type thermometer for measuring molten metal temperature.

[Explanation of symbols]

1 ... Iron rod, 2 ... Internal insulating tube, 3 ... Molybdenum tube, 3
a ... bottom of molybdenum tube, 3b ... molybdenum rod, 4
… External insulation pipe, w… Molten steel.

Claims (2)

[Claims] 1. A thermocouple-type thermometer for measuring a molten metal temperature, which comprises a combination of two kinds of thermocouple metals, wherein an insulating tube made of a non-conductive refractory is interposed between the two kinds of metals and one end thereof is provided. A thermocouple-type thermometer for measuring the temperature of a molten metal, characterized in that an insulating tube made of a non-conductive refractory is fitted on the outside except the side. 2. A thermocouple type thermometer for measuring a molten metal temperature, comprising a combination of two kinds of thermocouple metals, wherein an insulating tube made of a non-conductive refractory is externally fitted to each of the two kinds of metals. A thermocouple type thermometer for measuring a molten metal temperature, characterized in that one end side of each of these metals is opened.