Temperature measuring probe

Abstract

In high-temperature environments, this system allows for continuous temperature measurement of a distal object using an inexpensive configuration. [Solution] The temperature measuring probe of the present invention comprises a thermocouple having a sheath containing thermocouple wires, wherein a portion of the sheath is placed in a temperature environment higher than the normal operating limit of the thermocouple, and a flexible protective structure for heat-resistant protection of the sheath is provided on the outer circumference of the sheath, and the protective structure is composed of a heat-resistant layer disposed on the outer circumference of the sheath and an alumina paper layer disposed on the outer circumference of the heat-resistant layer.

Description

Technical Field

[0001] The present invention relates to a temperature measuring probe.

Background Art

[0002] As a measuring means for measuring the temperature of an object in a high-temperature environment such as inside a heating furnace of a hot rolling facility, a temperature measuring probe equipped with a thermocouple can be mentioned. For example, since the temperature inside the heating furnace becomes as high as about 1300 °C, as a temperature measuring probe, an R thermocouple with an upper limit of the temperature that can be continuously used (hereinafter, normal use limit) set to about 1400 °C, or a B thermocouple with a normal use limit set to 1500 °C is desirable. However, since R thermocouples and B thermocouples are expensive, attempts have been made to use a temperature measuring probe equipped with a K thermocouple whose normal use limit is set lower than that of R thermocouples and B thermocouples, at about 1200 °C.

[0003] As a method for preventing disconnection of a thermocouple (specifically, a thermocouple wire) in a high-temperature environment, for example, a thermocouple is housed inside a protective tube made of a molybdenum-zirconia (Mo-ZrO2) based refractory, and a sleeve is fitted around the protective tube (see Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The temperature sensor disclosed in Patent Document 1 is used by inserting it, for example, through an insertion hole 17 in the lid 16 of a tundish, and immersing the sleeve 5 and protective tube 6 of the temperature sensor in the molten material 18. It is not intended for measuring the temperature of an object located at a distance. Therefore, when measuring the temperature of an object located at a distance using the temperature sensor disclosed in Patent Document 1, the protective tube and sleeve must be shaped to match the condition of the conductor to the object being measured, making the temperature sensor itself expensive. Consequently, there is a demand for a low-cost configuration that can continuously measure the temperature of an object located at a distance in a high-temperature environment.

[0006] The present invention aims to provide a temperature measuring probe that can continuously measure the temperature of a distal object in a high-temperature environment with an inexpensive configuration. [Means for solving the problem]

[0007] One type of temperature-measuring probe is a thermocouple having a sheath containing thermocouple wires, wherein a portion of the sheath is placed in a temperature environment higher than the normal operating limit of the thermocouple, and is characterized in that a flexible protective structure for heat-resistant protection of the sheath is provided on the outer circumference of the sheath, and the protective structure is composed of a heat-resistant layer disposed on the outer circumference of the sheath and an alumina paper layer disposed on the outer circumference of the heat-resistant layer.

[0008] Furthermore, it is preferable that the heat-resistant layer is constructed by wrapping a heat-resistant tape with a construction thickness of 7 mm or more around the outer surface of the sheath.

[0009] Furthermore, it is preferable that the heat-resistant layer is composed of a first heat-resistant layer formed by wrapping a first heat-resistant tape around the outer surface of the thermocouple, and a second heat-resistant layer formed by wrapping a second heat-resistant tape around the outer surface of the first heat-resistant layer.

[0010] Furthermore, the heat-resistant layer is preferably constructed by wrapping it with a heat-resistant tape made of long fibers, such as silica tape, alumina tape, or glass tape.

[0011] Furthermore, it is preferable that the heat-resistant tape is bonded to the outer surface of the sheath using an adhesive.

[0012] Furthermore, the alumina paper layer is preferably constructed by wrapping two or more turns of alumina paper around the outer surface of the heat-resistant layer. The alumina paper is preferably heat-resistant, capable of withstanding temperatures up to 1600°C. [Effects of the Invention]

[0013] According to this disclosure, it is possible to continuously measure the temperature of an object located distal to the object being measured in a high-temperature environment using an inexpensive configuration. [Brief explanation of the drawing]

[0014] [Figure 1] Figure 1 is a schematic cross-sectional view showing an example of the internal configuration of a heating furnace. [Figure 2] Figure 2 is a magnified view of the vicinity of the temperature measuring probe. [Figure 3] Figure 3(a) is a schematic cross-sectional view showing an example of a protective structure in the first embodiment, and Figure 3(b) is a cross-sectional view of AA in Figure 3(a). [Figure 4] Figure 4(a) is a schematic cross-sectional view showing an example of a protective structure in the second embodiment, and Figure 4(b) is a cross-sectional view of BB in Figure 4(a). [Modes for carrying out the invention]

[0015] The present invention will now be described with reference to the drawings, describing a temperature measuring probe and a heating furnace in which the temperature measuring probe is installed. Figure 1 is a schematic cross-sectional view showing an example of the internal configuration of the heating furnace. Figure 2 is a magnified view of the vicinity of the temperature measuring probe.

[0016] The temperature measurement probe 10 shown in this embodiment functions as a temperature measurement means for measuring the temperature of the outer peripheral surface of the water-cooled pipe 61 that constitutes the piping equipment 60 provided inside the heating furnace 50. The temperature measurement probe 10 is inserted into the heating furnace 50 from the insertion hole 52 provided in the side wall 51 of the heating furnace 50. The temperature measurement probe 10 inserted into the heating furnace 50 is arranged along the floor FL of the heating furnace 50. Note that the wiring state of the temperature measurement probe 10 is merely an example and does not need to be limited to this.

[0017] The tip of the temperature measurement probe 10 is connected to the piping equipment 60 arranged at a predetermined height from the floor surface in a state of being bent in a crank shape toward the piping equipment 60. The temperature measurement contact 21 of the thermocouple 20 inside the temperature measurement probe 10 is held in a state of contacting, for example, the outer peripheral surface of the water-cooled pipe 61 that constitutes the piping equipment 60.

[0018] The piping equipment 60 is composed of a water-cooled pipe 61 and a heat insulating material 62 that covers the water-cooled pipe 61. The heat insulating material 62 is provided with an insertion hole 63, and the tip portion of the sheath 22 of the thermocouple 20 described later is inserted through the insertion hole 63.

[0019] The temperature measurement probe 10 is composed of a thermocouple 20 and a protection structure 30. As the thermocouple 20, for example, a K thermocouple with a normal temperature limit set to, for example, 1200 °C is used. Here, the temperature inside the heating furnace 50 is, as an example, about 1300 °C. That is, the thermocouple 20 is used in a high-temperature environment higher than the normal use limit of the thermocouple 20.

[0020] The thermocouple 2 is, for example, a non-grounded thermocouple. In the thermocouple 20, the temperature measurement contact 21, the sheath 22, the sleeve 23, and the compensation conductor (lead wire) 24 are arranged in the order of the temperature measurement contact 21, the sheath 22, the sleeve 23, and the lead wire 24 along the central axis (C1) direction from the tip side of the thermocouple 20. A plug (not shown) connected to a temperature measurement device such as a digital multimeter is connected to the lead wire 24.

[0021] Here, since the configuration of the thermocouple 20 is well-known, the description of each component of the thermocouple 20 will be omitted. In FIG. 2, a non-grounded thermocouple is illustrated as the thermocouple 20, but it is also possible to use a grounded thermocouple or an exposed thermocouple.

[0022] The protective structure 30 is provided so as to cover a part of the outer peripheral surface of the sheath 22 of the thermocouple 20. Note that the temperature measurement contact 21 of the thermocouple 20 is exposed without being covered by the protective structure 30 in order to quickly and accurately measure the site to be temperature-measured. The part where the protective structure 30 covers the outer peripheral surface of the sheath 22 is, for example, a part that directly contacts the atmosphere (inside-furnace atmosphere) inside the heating furnace 50. On the other hand, it is not always necessary to provide the protective structure 30 for the part of the outer peripheral surface of the sheath 22 that is embedded in the heat insulating material 62 of the piping equipment 60 or the part located outside the heating furnace 50.

[0023] The above-described protective structure 30 has flexibility. That is, if the sheath 22 has flexibility, the sheath 22 can be bent together with the protective structure 30.

[0024] Next, the configuration of the protective structure 30 will be described. Hereinafter, a case where the protective structure 30 is provided from one heat-resistant layer 31 and one alumina paper layer 32 provided outside the heat-resistant layer 31 will be described as the first embodiment.

[0025] [[ID=1s]] <First Embodiment> FIG. 3(a) is a schematic cross-sectional view showing an example of the protective structure in the first embodiment, and FIG. 3(b) is a cross-sectional view taken along the line A-A in FIG. 3(a). The cross-section shown in FIG. 3(b) is a cross-section in a plane including the central axis C1.

[0026] As shown in FIGS. 3(a) and 3(b), the protective structure 30 is provided so as to cover at least a part of the outer peripheral surface of the sheath 22 of the thermocouple 20. The protective structure 30 includes a heat-resistant layer 31 provided outside the sheath 22 and an alumina paper layer 32 provided outside the heat-resistant layer 31.

[0027] The heat-resistant layer 31 is formed by wrapping a heat-resistant tape, such as silica tape, alumina tape, or glass tape, which is made from long fibers, around the outer surface of the sheath 22.

[0028] In detail, a long piece of heat-resistant tape is wound multiple times, for example, five or six times, at the same position along the longitudinal direction of the sheath 22, and then cut. A similar process is repeated, shifting the position from the previously wound position by the width of the long piece of heat-resistant tape. This generates the heat-resistant layer 31.

[0029] Here, the heat-resistant tape that is wrapped over the previously wrapped tape at a position shifted by the width of the long heat-resistant tape is wrapped tightly over the previously wrapped heat-resistant tape without leaving any gaps.

[0030] Here, the thickness TH1 of the heat-resistant layer 31 is, for example, 5 mm or more. Preferably, the thickness TH1 of the heat-resistant layer 31 is 7 mm. Here, the heat-resistant layer 31 is made of a heat-resistant tape with a thickness of, for example, 5 mm and a width of, for example, 50 mm.

[0031] Although the heat-resistant tape forming the heat-resistant layer 31 is described as being wrapped around the outer surface of the sheath 22, it may also be adhered to the outer surface of the sheath 22 using an adhesive such as silica sol when wrapping it around the outer surface of the sheath 22.

[0032] The alumina paper layer 32 is constructed, for example, by wrapping alumina paper around the outer surface of the heat-resistant layer 31. The heat resistance temperature of the alumina paper is preferably, for example, 1600°C or higher. The alumina paper layer 32 is constructed, for example, by wrapping one or more turns of alumina paper. Here, the thickness TH2 of the alumina paper layer 32 is preferably 2 mm or more.

[0033] In the first embodiment, a protective structure 30 having one heat-resistant layer 31 and an alumina paper layer 32 provided on the outside of the heat-resistant layer 31 is described, but two or more heat-resistant layers may be provided. Hereinafter, a protective structure having two heat-resistant layers will be described as the second embodiment.Hereafter, in describing the protective structure of the second embodiment, the same components as in the first embodiment are denoted by the same reference numerals.In addition, in the following description, the temperature measuring probe in the second embodiment will be denoted by reference numeral 10' and the protective structure by reference numeral 30'.

[0034] <Second Embodiment> Figure 4(a) is a schematic cross-sectional view showing an example of a protective structure in the second embodiment, and Figure 4(b) is a cross-sectional view of BB in Figure 4(a). Note that the cross-section shown in Figure 4(b) is a cross-section in a plane including the central axis C1.

[0035] As shown in Figures 4(a) and 4(b), the protective structure 30' is provided to cover at least a portion of the outer circumferential surface of the sheath 22 of the thermocouple 20, similar to the protective structure 30 shown in the first embodiment.

[0036] The protective structure 30' comprises a heat-resistant layer 31' provided on the outside of the sheath 22 of the thermocouple 20, and an alumina paper layer 32 provided on the outside of the heat-resistant layer 31'.

[0037] The heat-resistant layer 31' consists of a first heat-resistant layer 41 provided on the outside of the sheath 22 of the thermocouple 20, and a second heat-resistant layer 42 provided on the outside of the first heat-resistant layer 41.

[0038] The first heat-resistant layer 41 is formed by wrapping a heat-resistant tape, such as silica tape, alumina tape, or glass tape, which is made from long fibers, around the outer surface of the sheath 22.

[0039] In detail, a long piece of heat-resistant tape is wound in multiple layers, for example, five or six times, at the same position along the longitudinal direction of the sheath 22, and then cut. A similar process is repeated, shifting from the previously wound position by the width of the long piece of heat-resistant tape. This generates the first heat-resistant layer 41.

[0040] Here, the heat-resistant tape that is wrapped over the previously wrapped tape at a position shifted by the width of the long heat-resistant tape is wrapped tightly over the previously wrapped heat-resistant tape without leaving any gaps.

[0041] The second heat-resistant layer 42 is formed, similar to the first heat-resistant layer 41, by wrapping a heat-resistant tape made from long fibers, such as silica tape, alumina tape, or glass tape, around the outer surface of the first heat-resistant layer 41.

[0042] In detail, a long piece of heat-resistant tape is wrapped, for example, twice over the first heat-resistant layer 41 at the same position along the longitudinal direction of the sheath 22, and then cut. A similar process is repeated, shifting the position from the previously overlapped winding point by the width of the long piece of heat-resistant tape. This generates a second heat-resistant layer 42.

[0043] Here, the heat-resistant tape that is wrapped over the previously wrapped tape at a position shifted by the width of the long heat-resistant tape is wrapped tightly over the previously wrapped heat-resistant tape without leaving any gaps.

[0044] Furthermore, when the heat-resistant tape forming the second heat-resistant layer 42 is wrapped around the first heat-resistant layer 41, the heat-resistant tape covers the joints between the ends of the heat-resistant tape forming the first heat-resistant layer 41. In other words, the heat-resistant tape forming the second heat-resistant layer 42 is wrapped around the heat-resistant tape forming the first heat-resistant layer 41 with a predetermined offset in the direction of the central axis.

[0045] The heat-resistant tape wrapped as the first heat-resistant layer 41 and the heat-resistant tape wrapped as the second heat-resistant layer 42 may be of the same type or of different types.

[0046] Here, the thickness TH3 of the heat-resistant layer 31' is preferably 7 mm or more. At this time, the thickness TH4 of the first heat-resistant layer 41 is preferably, for example, 5 mm or more. Also, the thickness TH5 of the second heat-resistant layer 42 is preferably, for example, 2 mm or more.

[0047] Table 1 shows the temperature measurement results when the temperature of the outer surface of the water-cooled pipe 61 of the piping system 60 is continuously measured using the temperature measuring probes 10 and 10' shown in the first and second embodiments, when the internal temperature of the heating furnace 50 reaches 1300°C.

[0048] [Table 1]

[0049] Examples 1 to 3 describe temperature measuring probes 10 using the protective structure 30 described in the first embodiment. Examples 4 to 6 describe temperature measuring probes 10' using the protective structure 30' described in the second embodiment. Comparative Examples 1 to 3 describe temperature measuring probes with only one heat-resistant layer as the protective structure, and Comparative Example 4 describes a temperature measuring probe with only an alumina paper layer as the protective structure. In Examples 1 to 3, the protective structure 30 consists of one heat-resistant layer 31 and one alumina paper layer 32. Therefore, in Table 1, the heat-resistant layer 31 in the protective structure 30 in Examples 1 to 3 is referred to as the first heat-resistant layer.

[0050] The protective structure 30 used in Example 1 consists of a heat-resistant layer 31 with a thickness of 5 mm using silica tape and an alumina paper layer 32 with a thickness of 2 mm, which is made by winding 2 mm thick alumina paper once.

[0051] Furthermore, the protective structure 30 used in Example 2 consists of a heat-resistant layer 31 with a thickness of 5 mm using silica tape and an alumina paper layer 32 with a thickness of 2 mm made by rolling two 1 mm thick alumina papers.

[0052] Furthermore, the protective structure 30 used in Example 3 consists of a 7 mm thick heat-resistant layer 31 made of silica tape and a 2 mm thick alumina paper layer 32 made by rolling two 1 mm thick alumina papers.

[0053] The protective structure 30' used in Example 4 consists of a first heat-resistant layer 41 with a thickness of 5 mm using silica tape, a second heat-resistant layer 42 with a thickness of 2 mm using silica tape, forming a heat-resistant layer 31', and a 2 mm thick alumina paper layer 32 formed by rolling two 1 mm thick alumina papers.

[0054] The protective structure 30' used in Example 5 consists of a first heat-resistant layer 41 with a thickness of 5 mm using alumina tape, a second heat-resistant layer 42 with a thickness of 2 mm using alumina tape, forming a heat-resistant layer 31', and a 2 mm thick alumina paper layer 32 formed by rolling two 1 mm thick alumina papers.

[0055] The protective structure 30' used in Example 6 consists of a first heat-resistant layer 41 with a thickness of 5 mm using glass tape, a second heat-resistant layer 42 with a thickness of 2 mm using glass tape, forming a heat-resistant layer 31', and a 2 mm thick alumina paper layer 32 formed by rolling two 1 mm thick alumina papers.

[0056] Furthermore, the protective structure used in Comparative Example 1 consists of a 5mm thick heat-resistant layer made solely of silica tape. Similarly, the protective structure used in Comparative Example 2 consists of a 5mm thick heat-resistant layer made solely of alumina tape. Furthermore, the protective structure used in Comparative Example 3 consists of a 5mm thick heat-resistant layer made solely of glass tape. Finally, the protective structure used in Comparative Example 4 consists of a 2mm thick alumina paper layer made solely of alumina paper.

[0057] The continuous measurement time was defined as the time from the start of temperature measurement until the thermocouple broke and measurement became impossible. The continuous measurement time was 3 days for the temperature measuring probe 10 shown in Example 1, 1 week for the temperature measuring probe 10 shown in Example 2, and 2 weeks for the temperature measuring probe 10 shown in Example 3. Furthermore, for the temperature measuring probes 10' shown in Examples 4 to 6, it was 1 month.

[0058] On the other hand, with the temperature measuring probes shown in Comparative Examples 1 to 3, continuous measurement was not possible because the wires broke immediately after use. Furthermore, with the temperature measuring probe shown in Comparative Example 4, an attempt was made to wrap alumina paper directly around the outer surface of the sheath 22 of the thermocouple 20, but the alumina paper slid on the sheath 22, making it impossible to firmly fix the alumina paper to the sheath 22. Therefore, it was found that the temperature measuring probe shown in Comparative Example 4 could not be manufactured or installed.

[0059] Thus, it was found that by using temperature measuring probes 10, 10' having a two-layer protective structure 30 or a three-layer protective structure 30', the wires inside the sheath 22 of the thermocouple 20 do not break even in high-temperature environments exceeding the normal operating limit of the thermocouple 20, and temperature can be measured continuously.

[0060] On the other hand, in the case of a protective structure consisting only of a heat-resistant layer, the heat resistance temperature of the heat-resistant layer is low, causing the installed temperature-measuring probe to break during temperature measurement, and the wires inside the sheath 22 of the thermocouple 20 to easily break. As a result, it was found that continuous temperature measurement is not possible. In the case of a protective structure consisting only of an alumina paper layer, it was found that it is difficult to tightly fix the alumina paper on the sheath 22, and therefore a protective structure consisting only of an alumina paper layer cannot be manufactured.

[0061] In this embodiment, the case where a K-type thermocouple is used as the thermocouple when the internal temperature of the heating furnace 50 is 1300°C is given as an example. However, the temperature of the environment in which the thermocouple is wired, and the type of thermocouple used for that temperature, are not limited to this. In other words, it is possible to use a thermocouple whose normal operating limit is set below the temperature of the environment in which the thermocouple is wired.

[0062] In this embodiment, a heat-resistant layer is formed by wrapping a 5mm thick heat-resistant tape around the sheath 22. However, it is also possible to form two or more heat-resistant layers using, for example, a heat-resistant tape with a thickness of about 1mm.

[0063] <Summary of effects> The temperature measuring probes 10, 10' of this embodiment are characterized in that they include a thermocouple 20 having a sheath 22 containing thermocouple wires, and a portion of the sheath 22 is disposed in a temperature environment higher than the normal operating limit of the thermocouple 20, and a flexible protective structure 30, 30' for heat-resistant protection of the sheath 22 is provided on the outer circumference of the sheath 22, and the protective structure 30, 30' is composed of a heat-resistant layer 31, 31' disposed on the outer circumference of the sheath 22 and an alumina paper layer 32 disposed on the outer circumference of the heat-resistant layer 31, 31'.

[0064] According to this, by providing protective structures 30, 30' on the temperature measuring probes 10, 10', it is possible to prevent the thermocouple wires enclosed in the sheath 22 from breaking, even when measuring the temperature of a distal object using an inexpensive K-type thermocouple in a high-temperature environment. As a result, it becomes possible to continuously measure the temperature of an object even with an inexpensive K-type thermocouple.

[0065] Furthermore, according to the present invention, heat resistance performance in the temperature measuring probes 10, 10' can be ensured with an inexpensive configuration in which a heat-resistant layer 31, 31' is formed by wrapping a heat-resistant tape around the outer circumference of the sheath 22, and an alumina paper layer 32 is formed by wrapping alumina paper around the outer circumference of the heat-resistant layer 31, 31'. [Explanation of Symbols]

[0066] 10, 10' temperature measuring probe 20 Thermocouples 21 Temperature sensing junction 22 Sheath 23 sleeves 30, 30' protection structure 31,31' Heat resistant layer 32 Alumina paper layer 41. First heat-resistant layer 42. Second heat-resistant layer

Claims

1. A temperature measuring probe comprising a thermocouple having a sheath containing thermocouple wires, wherein a portion of the sheath is placed in a temperature environment higher than the normal operating limit of the thermocouple, A flexible protective structure for heat-resistant protection of the sheath is provided on the outer circumference of the sheath. A temperature measuring probe comprising a protective structure consisting of a heat-resistant layer disposed on the outer circumference of the sheath and an alumina paper layer disposed on the outer circumference of the heat-resistant layer.

2. The temperature measuring probe according to claim 1, wherein the heat-resistant layer is formed by wrapping a heat-resistant tape with a construction thickness of 7 mm or more around the outer surface of the sheath.

3. The aforementioned heat-resistant layer is A first heat-resistant layer is formed by wrapping a first heat-resistant tape around the outer surface of the thermocouple, A temperature measuring probe according to claim 1, comprising a second heat-resistant layer formed by wrapping a second heat-resistant tape around the outer surface of the first heat-resistant layer.

4. The temperature measuring probe according to claim 1, wherein the heat-resistant layer is formed by wrapping a heat-resistant tape made of long fibers, which is a silica tape, an alumina tape, or a glass tape.

5. The temperature measuring probe according to claim 4, wherein the heat-resistant tape is bonded to the outer surface of the sheath using an adhesive.

6. The temperature measuring probe according to claim 1, wherein the alumina paper layer is formed by wrapping two or more turns of alumina paper around the outer surface of the heat-resistant layer.

7. The alumina paper has heat resistance that can withstand up to 1600°C, as described in claim 6.

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