JP2001194244A - Temperature measuring instrument for exhaust gas from gas turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a thermocouple to be easily pulled out of a protective tube by preventing the seizure of a positioning tool which is used for positioning the thermocouple when the thermocouple is inserted into the protective tube. SOLUTION: The element wires of the thermocouple 11 which measures the temperature of the exhaust gas from a gas turbine are housed in a metallic sheath 41. On the outer periphery of the sheath 41, the annular positioning tool 37 is fixed by welding and the tool 37 has a plurality of steps 49 on its outer peripheral surface so that annular projections 51 may come into line- contact with the tapered stopper surface 47 of the protective tube 15. On the stopper surface 47 of the tube 15, in addition, a oxidized coating film is formed in advance by heating.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermocouple which is installed in a flow path of a combustion gas discharge side of a gas turbine so that a tip thereof protrudes, and which measures exhaust gas. The present invention relates to an exhaust gas temperature measurement device for a gas turbine including a protection tube fixed to a flow path wall.

[0002]

2. Description of the Related Art In recent years, gas turbines have been widely used for power generation and industrial use. This is because the gas turbine combustor outlet temperature, that is, the turbine inlet gas temperature is 11
It is possible to increase the efficiency of the gas turbine alone from the 00 ° C class to the 1300 ° C class or higher, and a power generation system aiming to improve the thermal efficiency of the gas turbine and the steam turbine together, that is, combined cycle power generation This is because the plant has increased.

In the above-described combined cycle power plant, the temperature of the combustion gas at the inlet of the main gas turbine is
By raising the temperature to the above 1300 ° C class, higher efficiency
High output is realized. For this reason, in the power generation plant, a combined cycle power generation system using a gas turbine is mainly used.

In the operation of a gas turbine, it is necessary to measure the gas turbine inlet temperature for protection of the gas turbine. However, since the gas in this portion has a high temperature of 1300 ° C. and a high flow rate as described above, it is difficult to measure with a thermocouple. The reason is that if the thermocouple and its protection tube are placed in such a fluid, they are easily damaged, and sufficient reliability cannot be secured.

For this reason, a general gas turbine employs a method of measuring the temperature of gas discharged from the gas turbine and controlling the inlet temperature of the gas turbine based on the temperature of the discharged gas. The turbine inlet temperature can be determined from the exhaust gas temperature of the gas turbine by a thermodynamic method.

As described above, the measurement of the exhaust gas temperature of the gas turbine is one of the most important items in the safety protection of the equipment. FIG. 5 is an external view of the gas turbine showing only the upper half, in which compressed air heated to high temperature in the combustor 1 is passed through the exhaust frame 5 by the turbine in the gas turbine casing 3 to the rear diffuser. It is sent to the flow path in 7 and is discharged as the exhaust gas G. A plurality of thermocouple mounting holes 9 are formed in the flow path wall of the rear diffuser 7 over the entire circumference.

FIG. 6 shows a state in which a temperature measuring device 13 having a thermocouple 11 is attached to the thermocouple attachment hole 9. The temperature measuring device 13 is provided with a protective tube 15 for accommodating the thermocouple 11, the protective tube 15 is inserted into the thermocouple mounting hole 9, and a periphery of a mounting flange 17 formed on an outer periphery thereof is rearward. It is fixed to the flow path wall of the diffuser 7 by welding.

FIG. 7 is an enlarged view of the temperature measuring device 13, and the right half in the figure is shown in cross section. The protection tube 15
It has a through-hole 19 for accommodating the thermocouple 11 inside, and has a cylindrical rectification portion 21 at the tip, and the thermocouple is positioned so that the tip is located in a passage 21 a penetrating right and left in the drawing in the rectification portion 21. 11 are accommodated. The passage 21a described above
Is set to be parallel to the flow direction of the exhaust gas G.

The thermocouple 11 is fixed to the protective tube 15 by a fixing member 23 at the upper end in FIGS. The fixture 23 includes a main body 27 that is fastened to the protective tube 15 via a screw portion 25, and a nut 31 that is fastened to the main body 27 via a screw portion 29. An inner peripheral portion of the nut 31 is provided with an end 33a on the outer peripheral side of the pressing piece 33, and the pressing piece 33 is pressed by a pressing portion 27a on the main body 27 side in the figure by fastening the nut 31 to the main body 27. With this, the inner peripheral surface of the pressing piece 33 is pressed against the outer peripheral surface of the thermocouple 11 and the thermocouple 11 is fixed.

As shown in FIG. 7 (not shown in FIG. 6), a heat insulating material 35 is provided on an outer peripheral portion of the rear diffuser 7 including a portion to which the temperature measuring device 13 is attached. The heat insulating material 35 is provided to effectively utilize the heat of the exhaust gas to a steam turbine (not shown), and covers the entire protective tube 15 on the upper side in FIG. .

As shown in FIG. 7, the thermocouple 11 is housed in the center of the through hole 19 in the protection tube 15 and has an annular shape for positioning the tip so as to be located at the center of the passage 21 a in the rectifying section 21. A positioning tool 37 is provided. FIG. 8 is an enlarged cross-sectional view around the positioning tool 37. The thermocouple 11 has a configuration in which a thermocouple wire 39 is accommodated in a hollow metal sheath 41. Both are fixed by welding while being inserted into the insertion hole 43.

[0012] In the figure around the lower side of the positioning tool 37,
A tapered surface 45 is formed, and a stopper surface 47 is formed on the inner surface of the through hole 19 corresponding to the tapered surface 45. The thermocouple 11 to which the positioning tool 37 is fixed by welding is inserted into the through hole 19 of the protective tube 15 from above in FIG. 7, and the taper surface 45 of the positioning tool 37 is brought into close contact with the stopper surface 47 of the through hole 19. The thermocouple 11 is housed in the center of the through-hole 19 and the tip is positioned at the center of the passage 21 a in the rectifying section 21. After this positioning operation, the nut 31 of the fixture 23 in which the thermocouple 11 is inserted in advance is fixed to the protective tube 15 by the main body 2.
7, the thermocouple 11 is fixed to the protection tube 15.

[0013]

By the way, as described above, the exhaust gas temperature of the gas turbine is also higher due to the higher combustion gas temperature accompanying the higher efficiency of the gas turbine. Therefore, in the positioning structure for the thermocouple 11 with respect to the protection tube 15 as shown in FIG.
Is in contact with the stopper surface 47 of the protection tube 15, seizure occurs on this contact surface, and the thermocouple 11 cannot be pulled out from the protection tube 15.

When the heat insulating material 35 covers the screw portion 25 for fastening and fixing the fixture 23 to the protective tube 15 as shown in FIG. 7, the screw portion 25 is also maintained at a high temperature. As a result, burn-in occurs, and the same problem as described above occurs.

Since the thermocouple 11 is used for protection and combustion control of the gas turbine, it is necessary to enhance the response of temperature measurement. Since the thermocouple wire 39 is extremely thin, the thermocouple wire 39 is easily broken, and is replaced. Need. However,
As described above, if the thermocouple 11 cannot be pulled out of the protection tube 15 due to burn-in, the thermocouple 11 alone cannot be replaced, and the protection tube 15 welded and fixed to the rear diffuser 7 must be replaced. A long time is required for the replacement work, which is a factor that significantly impairs the operation of the equipment.

Therefore, the present invention protects the thermocouple by preventing the positioning portion for positioning the thermocouple to the protection tube and the fixing device for fixing the thermocouple to the protection tube from sticking to the protection tube. It is intended to be easily pulled out of the tube.

[0017]

In order to achieve the above object, according to the first aspect of the present invention, the temperature of an exhaust gas is measured by installing the tip of the gas turbine in a flow path on the exhaust gas exhaust side so as to project. An exhaust gas temperature measuring device for a gas turbine, comprising: a thermocouple; and a protection tube in which the thermocouple is housed and fixed to the gas discharge side flow path wall. A positioning portion that regulates the movement of the thermocouple toward the distal end with respect to the protection tube is provided between the peripheral portion and the periphery, and the mutual contact portions in the positioning portion are in a point or line contact state.

According to the exhaust gas temperature measurement device for a gas turbine having such a configuration, when the thermocouple is inserted into the protection tube, the positioning portion restricts the movement of the thermocouple toward the distal end side with respect to the protection tube and positions the thermocouple. . At this time, the thermocouple and the protection tube are in a point or line contact state at the positioning portion, which is effective in preventing image sticking.

According to a second aspect of the present invention, in the configuration of the first aspect, one of the contact portions has a tapered surface.

According to the above configuration, the other contact portion makes point or line contact with the tapered surface, whereby the thermocouple is positioned in the radial direction with respect to the protection tube.

According to a third aspect of the present invention, in the configuration of the second aspect of the present invention, the contact portion is constituted by an annular projection whose other line is in line contact with the tapered surface.

According to the above configuration, the annular protrusion linearly contacts the tapered surface, so that the movement of the thermocouple toward the distal end with respect to the protection tube is regulated and positioned.

According to a fourth aspect of the present invention, in the configuration of the third aspect, a plurality of annular projections are formed.

According to the above configuration, the positioning of the thermocouple in the radial direction with respect to the protection tube is ensured.

According to a fifth aspect of the present invention, in the configuration of the third or fourth aspect, the annular projection is provided on the thermocouple side.

According to the above configuration, before the thermocouple is incorporated into the protective tube, the annular projection is exposed to the outside, so that the annular projection can be easily formed.

According to a sixth aspect of the present invention, in the configuration according to any one of the second to fifth aspects, an oxidation-resistant coating is formed on at least a tapered surface side of a mutual contact portion between the thermocouple and the protection tube. .

According to the above-described structure, by forming an oxidation-resistant film on the tapered surface, oxidation due to high temperature is suppressed, which is effective in preventing image sticking.

According to a seventh aspect of the present invention, there is provided a thermocouple which is installed in a flow path on the combustion gas discharge side of a gas turbine so as to protrude and measures the temperature of the exhaust gas, and wherein the thermocouple is accommodated and the gas discharge is carried out. An exhaust gas temperature measurement device for a gas turbine, comprising: a protection tube fixed to a side flow path wall; a distal end side of the thermocouple with respect to the protection tube between an outer circumference of the thermocouple and an inner circumference of the protection tube. A positioning portion for restricting movement of the positioning portion is provided, and an oxidation-resistant film is formed on at least one of the mutual contact portions in the positioning portion.

According to the above arrangement, when the thermocouple is inserted into the protection tube, the positioning portion restricts the movement of the thermocouple toward the distal end with respect to the protection tube, thereby positioning the thermocouple. At this time, the thermocouple and the protection tube come into contact with each other via the oxidation-resistant coating at the positioning portion, which is effective in preventing image sticking.

According to an eighth aspect of the present invention, in the configuration of the sixth or seventh aspect, the oxidation-resistant film is formed by heating at least the protective tube side by heating.

According to the above configuration, the positioning portion of the protection tube with respect to the thermocouple is located inside the hole into which the thermocouple is inserted. Therefore, when forming the oxidation resistant film, the oxide film is formed by heating. Is advantageous in terms of manufacturing.
By forming the oxide film in advance, oxidation is suppressed even in a high temperature atmosphere during use.

According to a ninth aspect of the present invention, in the configuration of the eighth aspect, an oxidation-resistant film is formed on the thermocouple by metal spraying.

According to the above configuration, the positioning portion for the thermocouple side with respect to the protection tube is exposed to the outside before assembling to the protection tube, so that metal spraying can be easily performed.

According to a tenth aspect of the present invention, there is provided a thermocouple for measuring the temperature of an exhaust gas, the thermocouple being installed so as to protrude from a flow path on a combustion gas exhaust side of a gas turbine, and the thermocouple being housed therein for the gas discharge. The exhaust gas temperature measurement device for a gas turbine, comprising: a protection pipe fixed to the side flow path wall; and a base end of the protection pipe, extending in a direction away from the fixing part of the protection pipe to the flow path wall. A protection tube extension into which the thermocouple is inserted, and a fixing tool for pressing and fixing the thermocouple from the outside to an end of the protection tube extension opposite to the protection tube, for fastening and fixing. is there.

According to the above construction, the entire area of the protection tube and the vicinity of the attachment portion of the protection tube extension to the protection tube are covered with, for example, a heat insulating material on the outer periphery of the flow path wall, and this vicinity is maintained at a high temperature. Even if it is performed, the heat on the protection tube side is radiated at the protection tube extension, and the temperature of the fastening portion fixed to the protection tube extension of the fixing tool is suppressed from becoming high, which is effective in preventing seizure of this portion.

According to an eleventh aspect of the present invention, in the configuration of the tenth aspect, a space is formed in a part of the mutually facing surfaces of the protection tube and the protection tube extension.

According to the above configuration, heat conduction from the protection tube to the protection tube extension is suppressed.

[0039]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention.
In the sectional view corresponding to FIG. 8 described in the conventional example, the same components as those in FIGS. 5 to 8 shown in the conventional example are denoted by the same reference numerals. The difference of this embodiment from the conventional one is that the positioning tool 37 welded and fixed to the outer periphery of the thermocouple 11 has the stopper surface 4 on the protection tube 15 side.
The tapered surface 45 (see FIG. 8) contacting with the nozzle 7 is provided with a plurality of annular steps 49 to form an annular projection 51, and the protective tube 15 is previously heated to a temperature of about an exhaust gas atmosphere (about 600 ° C.). To form an oxide film on the surface of the stopper surface 47 to form an oxidation-resistant film.

The stopper surface 47 and the projection 51 are
The contact portions are in contact with each other, and these contact portions constitute a positioning portion that regulates the movement of the thermocouple 11 toward the distal end side (the lower side in FIG. 1) with respect to the protection tube 15.

In the positioning portion, since the annular projection 51 is in line contact with the stopper surface 47 and an oxide film is already formed on the stopper surface 47, promotion of oxidation of the surface in a high-temperature atmosphere is suppressed. Therefore, even if the exhaust gas temperature becomes high as a gas turbine, the positioning tool 37
And the protection tube 15 can be prevented from burning. This allows the thermocouple 11 to be pulled out of the protection tube 15 and facilitates replacement of the thermocouple 11.

Since a plurality of the annular projections 51 are provided, each of the annular projections 51 comes into contact with the stopper surface 47 so that the vertical center line of the thermocouple 11 in FIG.
5 can be surely coincident with each other, and the positioning of the thermocouple 11 with respect to the protection tube 15 in the radial direction (the left-right direction in FIG. 1) can be performed more reliably.

By forming an oxidation-resistant coating on the portion of the positioning tool 37 where the projection 51 is formed, the prevention of image sticking can be further ensured. The oxidation resistant film in this case can be subjected to metal spraying in addition to the above-mentioned oxide film formed by heating. Further, a contact portion on the positioning tool 37 side that comes into contact with the tapered surface 47 is an annular projection 51.
However, the present invention is not limited to this, and a protrusion formed intermittently in the circumferential direction, a protrusion extending in the inclined direction of the tapered surface 47, or a protrusion that makes point contact with the tapered surface 47 may be used. In any case, any shape may be used as long as it does not make surface contact with the tapered surface 47 but makes point or line contact.

FIG. 2 shows another embodiment of the present invention. In this embodiment, instead of the step 49 and the projection 51 in FIG. 1, a metal spray is applied to the surface to form an oxidation-resistant film 53. In the positioning tool 37, an oxidation-resistant coating 53 is provided on a contact surface with the stopper surface 47.
Is formed, the seizure between the positioning tool 37 and the protective tube 15 can be prevented even when the exhaust gas temperature of the gas turbine rises.

As the oxidation resistant film 53, an oxide film formed by heating as described in the example of FIG. 1 can be formed instead of metal spraying. In the example of FIG. 2, a step similar to the step 49 of the positioning tool 37 shown in the example of FIG. You may make it do.

FIG. 3 shows a fixing structure for fixing the thermocouple 11 to the protective tube 15 shown in FIG. 7 with respect to the protective tube 15 side. In FIG. 3, only the right half is shown in cross section. A protection tube extension 55 smaller in diameter than the protection tube 15 is fixed to the upper end surface of the protection tube 15 by welding. An insertion hole 57 into which the thermocouple 11 is inserted is formed in the protection tube extension 55, and a female screw portion 59 is formed on an inner surface of an end of the insertion hole 57 opposite to the protection tube 15.

A fixing tool 23 similar to that shown in FIG. 7 is fastened and fixed to the female screw portion 59. That is,
The main body 27 of the fixture 23 is fastened and fixed to the female screw portion 59 of the protection tube extension 55. And the same heat insulating material 3 as before
5 covers only a part of the protection tube extension 55 on the side of the protection tube 15, and does not cover the female screw portion 59 serving as a fastening portion of the fixture 23 to the protection tube extension 55.

Therefore, the fastening portion is not kept at a high temperature by the heat retaining material 35, and the heat from the protection tube 15 is radiated by the protection tube extension portion 55 having a reduced diameter. Seizure of the fastening portion between the protection tube 23 and the protection tube extension 55 can be prevented. The fixing device 23 can be easily detached from the protection tube extension 55 by the seizure prevention, the thermocouple 11 can be pulled out from the protection tube 15, and the thermocouple 11 can be easily replaced.

FIG. 4 shows a modification of FIG.
A concave portion 61 is formed on a surface of the protective tube 15 facing the protective tube 15, and a space 63 is formed between the protective tube extension 55 and the protective tube 15. On the outer peripheral side of the concave portion 61, an annular contact portion 65 that contacts the end face of the protective tube 15 is formed.

When the space 63 is formed, the protection tube 15 is formed.
The amount of heat transferred from the to the protection tube extension 55 decreases,
Seizure of the fastening portion between the fixture 23 and the protection tube extension 55 is more reliably prevented. Further, by forming the concave portion 61, it is possible to prevent the protection tube extension 55 from cracking during welding.

In the example shown in FIG. 4, it is particularly desirable that the welding of the protection tube 15 and the protection tube extension 55 be performed over the entire circumference in order to ensure the sealing performance.

The above-mentioned concave portion 61 may be formed in the entire region inside the contact portion 65, but may be partially formed instead of the entire region. Further, instead of providing the concave portion 61 in the protective tube extension 55, a concave portion may be provided on the protective tube 15 side, or a concave portion may be provided in both the protective tube 15 and the protective tube extension 55. Good.

As described above, burn-in is prevented at the contact portion between the positioning member 37 for positioning the thermocouple 11 and the protection tube 15 and the protection tube 15, and the thermocouple 11 is protected integrally with the protection tube 15. Seizure is also prevented at the fastening portion between the fixture 23 for fixing to the tube extension 55 and the protection tube extension 55, so that the thermocouple 11 can be easily pulled out from the protection tube 15 and replaced. It becomes easier and the reliability of the equipment is improved.

[0055]

According to the first aspect of the present invention, the thermocouple and the protection tube make point or line contact with each other at a positioning portion for restricting the movement of the thermocouple toward the distal end with respect to the protection tube. As a result, seizure can be prevented at the contact portion between the thermocouple and the protection tube, and the thermocouple can be easily replaced.

According to the second aspect of the present invention, since one of the contact portions is formed of a tapered surface, the thermocouple is positioned in the radial direction with respect to the protection tube, and the contact between the thermocouple and the protection tube is made. Seizure at the contact portion can be prevented.

According to the third aspect of the present invention, since the contact portion is formed by the annular protrusion which is in line contact with the tapered surface, the thermocouple is brought into contact with the tapered surface by the annular protrusion. While the movement to the tip side with respect to the protection tube is regulated,
Seizure at the contact portion between the thermocouple and the protection tube can be prevented.

According to the fourth aspect of the present invention, the annular projection is
Since a plurality of thermocouples are formed, the positioning of the thermocouple with respect to the protection tube in the radial direction can be reliably performed.

According to the fifth aspect of the present invention, the annular projection is
Since it is provided on the thermocouple side, it is easy to form an annular projection.

According to the sixth aspect of the present invention, since the oxidation resistant coating is formed on at least the tapered surface side of the mutual contact portion between the thermocouple and the protection tube, it is possible to suppress oxidation due to high temperature.
Seizure at the contact portion between the thermocouple and the protection tube can be prevented.

According to the seventh aspect of the present invention, the thermocouple and the protection tube are provided with an acid-resistant material at least one of the mutual contact portions in the positioning portion for regulating the movement of the thermocouple toward the distal end with respect to the protection tube. Since the oxide film is formed, seizure can be prevented at the contact portion between the thermocouple and the protection tube, and the thermocouple can be easily replaced.

According to the invention of claim 8, the oxidation-resistant coating is
Since at least the protective tube side is formed by heating, an oxide film can be easily formed on the protective tube in which the contact portion for the thermocouple is formed.

According to the ninth aspect of the present invention, since the oxidation resistant coating is formed on the thermocouple by metal spraying, it is possible to prevent the seizure at the mutual contact portion between the thermocouple and the protection tube.

According to the tenth aspect of the present invention, an annular protection tube extension portion, which extends in a direction away from the fixing portion of the protection tube to the flow path wall and into which a thermocouple is inserted, is provided at the base end of the protection tube. Provided,
At the end of the protection tube extension opposite to the protection tube, a fixing tool for pressing and fixing the thermocouple from the outer periphery is fixed and fixed.
At a position away from the end of the protection tube, heat on the protection tube side is radiated by the extension of the protection tube, heat transfer to the fastening portion can be suppressed, seizure at the fastening portion can be prevented, and replacement of the thermocouple Can be easily performed.

According to the eleventh aspect of the present invention, since a space is formed in a part of the mutually facing surfaces of the protection tube and the protection tube extension, the transfer of heat from the protection tube to the protection tube extension can be suppressed. ,
Seizure of the fastening portion with respect to the protection tube extension of the fixture can be reliably prevented.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of the vicinity of a positioning portion of a thermocouple for a protection tube in a gas turbine temperature measurement device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the vicinity of a positioning portion with respect to a protection tube of a thermocouple in a gas turbine temperature measurement device according to another embodiment of the present invention.

FIG. 3 is an explanatory view showing only a right half of a periphery of a fixture with respect to a protection tube of a thermocouple in a cross section.

FIG. 4 is an enlarged sectional view of a main part showing a modification of FIG. 3;

FIG. 5 is an external view of a gas turbine showing an upper half.

FIG. 6 is a cross-sectional view showing a state where a temperature measuring device is attached to a rear diffuser of the gas turbine of FIG. 5;

FIG. 7 is an explanatory diagram showing the right half of the temperature measuring device in FIG.

FIG. 8 is an enlarged cross-sectional view around a positioning portion of the thermocouple with respect to the protection tube in FIG. 7;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Thermocouple 13 Temperature measuring device 15 Protective tube 23 Fixture 37 Positioning tool 47 Stopper surface (contact portion) 51 Annular protrusion (contact portion) 53 Oxidation-resistant coating 55 Protective tube extension 63 Space

Continued on the front page (72) Inventor Koji Matsudo 11-1 Ogurocho, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture F-term in the Yokohama Thermal Power Station of Tokyo Electric Power Co., Inc. 2F056 KC01 KC06 KC18

Claims (11)

[Claims] 1. A thermocouple which is installed in a flow path on the combustion gas discharge side of a gas turbine so as to protrude and measures the temperature of exhaust gas, and a wall of the gas discharge side where the thermocouple is accommodated. In a gas turbine exhaust gas temperature measurement device provided with a protection tube fixed to the thermocouple, movement of the thermocouple toward the distal end with respect to the protection tube is restricted between the outer periphery of the thermocouple and the inner periphery of the protection tube. An exhaust gas temperature measuring device for a gas turbine, comprising: a positioning section for performing positioning; and a mutual contact section in the positioning section being in a point or line contact state. 2. The exhaust gas temperature measuring device for a gas turbine according to claim 1, wherein one of the contact portions is formed of a tapered surface. 3. The contact portion is formed of an annular protrusion whose other line is in line contact with the tapered surface.
An exhaust gas temperature measuring device for a gas turbine as described in the above. 4. The exhaust gas temperature measuring device for a gas turbine according to claim 3, wherein a plurality of annular projections are formed. 5. The exhaust gas temperature measuring device for a gas turbine according to claim 3, wherein the annular projection is provided on a thermocouple side. 6. The exhaust gas of a gas turbine according to claim 2, wherein an oxidation-resistant coating is formed on at least a tapered surface side of a mutual contact portion between the thermocouple and the protection tube. Temperature measurement device. 7. A thermocouple which is installed in the gas turbine on a combustion gas discharge side flow path with its tip protruding to measure the temperature of the exhaust gas, and which contains the thermocouple and has a gas discharge side flow path wall. In a gas turbine exhaust gas temperature measurement device provided with a protection tube fixed to the thermocouple, movement of the thermocouple toward the distal end with respect to the protection tube is restricted between the outer periphery of the thermocouple and the inner periphery of the protection tube. An exhaust gas temperature measuring device for a gas turbine, characterized in that a positioning portion is provided, and an oxidation-resistant film is formed on at least one of the mutual contact portions of the positioning portion. 8. The exhaust gas temperature measuring device for a gas turbine according to claim 6, wherein the oxidation-resistant film is formed by heating at least on the protection tube side by heating. 9. An exhaust gas temperature measuring device for a gas turbine according to claim 8, wherein an oxidation-resistant film is formed on the thermocouple by metal spraying. 10. A thermocouple that is installed so that a tip thereof protrudes in a flow path on a combustion gas discharge side of a gas turbine and measures a temperature of an exhaust gas, and a flow path wall on the gas discharge side in which the thermocouple is housed. In a gas turbine exhaust gas temperature measurement device having a protection tube fixed to the protection tube, a base end of the protection tube is extended in a direction away from a fixing portion of the protection tube to a flow path wall, and the thermocouple is provided. A gas turbine, comprising: a protection tube extension portion to be inserted; and a fixing tool for pressing and fixing the thermocouple from the outside to an end of the protection tube extension portion on a side opposite to the protection tube. Exhaust gas temperature measurement device. 11. The exhaust gas temperature measuring device for a gas turbine according to claim 10, wherein a space is formed in a part of a surface facing the protection tube and the protection tube extension.