Monitoring probes and boilers

Abstract

A monitoring probe and a boiler are provided that can be made smaller and that make it easier to grasp the corrosion status at the installation location. [Solution] A monitoring probe 1 comprises a tubular portion 10, a two-electrode sensor 20 provided on the tubular portion 10 and used for electrochemical measurements, and an ultrasonic sensor 30, characterized in that one end side of a first electrode included in the two-electrode sensor 20 is located outside the tubular portion 10, and the other end side of the first electrode is located inside the tubular portion 10, and the ultrasonic sensor 30 is arranged on the part of the first electrode on the other end side, and the ultrasonic sensor 30 measures the thickness of the first electrode.

Description

[Technical Field]

[0001] The present disclosure relates to a monitoring probe and a boiler. [Background technology]

[0002] Conventionally, there are corrosion monitoring sensors for waste incinerator boilers and the like. Patent Document 1 discloses a monitoring probe that includes a cylindrical outer tube portion that is hollow inside, an ultrasonic sensor that is provided on the inner wall side of the outer tube portion and measures the thickness of the outer tube portion by ultrasonic waves reflected from the outer wall of the outer tube portion, a two-electrode sensor that is provided on the outer tube portion and measures the current value between two electrodes generated by melting of adhered ash, and a thermocouple that is provided on the outer tube portion and measures the temperature of the outer tube portion. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2024-75283 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in Patent Document 1, there is room for improvement in terms of miniaturizing the monitoring probe and making it easier to grasp the corrosion state at the installation location.

[0005] The present disclosure has been made in consideration of the above-mentioned circumstances, and aims to provide a monitoring probe and a boiler that can be made compact and that make it easier to grasp the corrosion status at the installation location. [Means for solving the problem]

[0006] A monitoring probe according to one aspect of the present disclosure comprises a tubular portion, a two-electrode sensor provided in the tubular portion and used for electrochemical measurements, and an ultrasonic sensor, wherein one end side of a first electrode included in the two-electrode sensor is located outside the tubular portion, and the other end side of the first electrode is located inside the tubular portion, the ultrasonic sensor is disposed in a portion of the first electrode on the other end side, and the ultrasonic sensor measures the thickness of the first electrode. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to provide a monitoring probe and a boiler that can be made smaller and that can easily grasp the corrosion status at the installation location. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram of a boiler provided with a monitoring probe according to an embodiment; [Figure 2] FIG. 2 is a cross-sectional view of a monitoring probe according to an embodiment. [Figure 3] FIG. 3 is an enlarged view of part III shown in FIG. 2. [Figure 4] FIG. 2 is a plan view of a two-electrode sensor. [Figure 5] FIG. 4 is an enlarged view of a V portion shown in FIG. [Figure 6] FIG. 6 is a cross-sectional view taken along the line VI-VI in FIG. [Figure 7] FIG. 7 is an enlarged view of part VII shown in FIG. 6, showing a first example of a sensor fixing part. [Figure 8] FIG. 10 is a diagram showing a second example of a sensor fixing part. [Figure 9] FIG. 10 is a diagram showing a third example of a sensor fixing part. [Figure 10] FIG. 1 is a schematic diagram showing the connection of a combination of an ultrasonic sensor and an electrode unit of a two-electrode sensor to a receiving device via a cable and a switch. [Figure 11]FIG. 2 is a second schematic diagram showing the connection of a combination of an ultrasonic sensor and an electrode unit of a two-electrode sensor to a receiving device via a cable and a switch. DETAILED DESCRIPTION OF THE INVENTION

[0009] A monitoring probe according to an embodiment of the present disclosure will now be described with reference to the drawings. The monitoring probe according to this embodiment is placed in, for example, a corrosive environment, and thereby derives the corrosion rate of the metal in the corrosive environment.

[0010] FIG. 1 is a schematic diagram of a boiler B provided with a monitoring probe 1 according to an embodiment. In this embodiment, the corrosive environment is, for example, a flue BS of a boiler B installed in a waste incinerator. As shown in Fig. 1, the boiler B is provided with, for example, a superheater tube BP and a monitoring probe 1.

[0011] The superheater tubes BP include, for example, superheater tubes, water tubes and evaporator tubes. The tubes BP of these superheaters are susceptible to problems such as low-temperature corrosion caused by condensation of acids in the exhaust gases and high-temperature corrosion caused by high-temperature molten salts in the ash contained in the exhaust gases. In this embodiment, the monitoring probe 1 is used to grasp the corrosion state at the installation location of the superheater tube BP (flue BS of boiler B). 1, the tip of the monitoring probe 1 is placed in a flue BS, which is a passageway for smoke S of a boiler B, and the base is connected to an outer wall BW of the boiler B. At this time, a manhole BF for connecting a tubular part 10, which will be described later, may be provided in the outer wall BW of the boiler B.

[0012] FIG. 2 is a cross-sectional view of the monitoring probe 1 according to the embodiment. FIG. 3 is an enlarged view of part III shown in FIG. As shown in Figures 1, 2 and 3, the monitoring probe 1 comprises a tubular portion 10, a two-electrode sensor 20, an ultrasonic sensor 30, a conductor 40, a conducting wire 41, a thermocouple 50, an insulating holder 60, a metal holder 70, a cable 80, a receiving device 90 and a switch A.

[0013] 1 and 2, the tubular portion 10 is a cylindrical member whose base side is connected to the inner wall of the boiler B and whose tip end extends toward the flue BS of the boiler B. A dustproof box DB is connected to the end of the tubular portion 10 on the base side via a purge pipe P. In this embodiment, the tubular portion 10 is cylindrical and includes a boiler flange 11 and a purge piping flange 12.

[0014] As shown in Fig. 2, the boiler flange 11 is a flange that is fixed to a manhole BF provided in an outer wall BW of the boiler B by a bolt BL. The manhole BF is provided on the side of the base of the tubular portion 10. This connects the base of the tubular portion 10 to the boiler B. In this embodiment, an insulating member I is provided between the boiler flange 11 of the tubular portion 10 and a manhole BF provided in the outer wall BW of the boiler B. In other words, the monitoring probe 1 and the boiler B are connected via the insulating member I. For example, a known insulating gasket is suitably used as the insulating member I.

[0015] The purge piping flange 12 is provided at the end on the base side of the tubular portion 10. The purge piping flange 12 is used to connect to a purge piping P located at the end on the base side of the tubular portion 10, as shown in FIG.

[0016] FIG. 4 is a plan view of the two-electrode sensor 20. The two-electrode sensor 20 is provided in the tubular portion 10 and is used for electrochemical measurements. In this embodiment, the two-electrode sensor 20 includes a first electrode unit 21, a second electrode unit 22, a third electrode unit 23, and a fourth electrode unit 24, as shown in FIG. 4. In this embodiment, the first electrode unit 21, the second electrode unit 22, the third electrode unit 23, and the fourth electrode unit 24 each have the same configuration. In the following description, when there is no need to distinguish between these electrode units, they may be simply referred to as electrode units. These electrode units are classified as a working electrode and a counter electrode depending on their use in electrochemical measurements. In this embodiment, the two-electrode sensor 20 functions by combining any two of the first electrode unit 21, the second electrode unit 22, the third electrode unit 23, and the fourth electrode unit 24.

[0017] Specifically, the two-electrode sensor 20 can measure, for example, the polarization resistance between two of the electrode units included in the two-electrode sensor 20 and the resistance of deposits attached to the outer peripheral surface of the tubular portion 10. In this way, the two-electrode sensor 20 can grasp the corrosion state of the tubular portion 10 in the monitoring probe 1. In this embodiment, the corrosion condition refers to, for example, whether or not ash has melted at the installation location of the monitoring probe 1, whether or not there is an oxide coating on the surface of the tubular portion 10, whether or not the oxide coating formed on the tubular portion 10 is an oxide coating with high corrosion resistance, and the corrosion rate of the tubular portion 10.

[0018] In this embodiment, each of the electrode units included in the two-electrode sensor 20 is preferably formed from the same material as the superheater tube BP, the corrosion state of which is to be determined. To reproduce the corrosive environment at the installation location of the superheater tube BP, the temperature of each of the electrode units included in the two-electrode sensor 20 may be adjusted, for example, by hot air. The hot air for adjusting the temperature of the electrode units may be, for example, about 500°C. The hot air may be generated by, for example, adjusting the temperature of air blown by a blower (not shown) using a heater (not shown). The temperature of the hot air may be determined using the temperature of each of the electrode units included in the two-electrode sensor 20 as a control variable. The temperature of the electrode units may be measured by a thermocouple 50, as described below.

[0019] The following description will be given using the first electrode unit 21 as an example, and for the second electrode unit 22, the third electrode unit 23, and the fourth electrode unit 24, only the differences from the first electrode unit 21 will be described, and descriptions of the same content will be omitted.

[0020] FIG. 5 is an enlarged view of the V portion shown in FIG. As shown in FIG. 5, the first electrode unit 21 includes an electrode portion 2a (electrode), a pressing block 2b, a sensor fixing portion 2c, and a conductor fixing plate 2d. The electrode section 2a is a portion that ensures the function of the electrode in the first electrode unit 21. In this embodiment, the electrode included in the two-electrode sensor 20 refers to the electrode section 2a. For example, the electrode section 2a included in the first electrode unit 21 may be referred to as the first electrode. Similarly, the electrode section 2a included in the second electrode unit 22 may be referred to as the second electrode, the electrode section 2a included in the third electrode unit 23 may be referred to as the third electrode, and the electrode section 2a included in the fourth electrode unit 24 may be referred to as the fourth electrode. In this embodiment, the electrode portion 2a includes a held portion 2a1, an exposed portion 2a2, and an intermediate portion 2a3, as shown in Fig. 5. The electrode portion 2a including these components may be integrally formed by, for example, a method such as machining.

[0021] The held portion 2a1 is a portion of the electrode portion 2a that includes the end portion on the side that does not face the pressing block 2b. As shown in Fig. 5, the held portion 2a1 is located inside the insulating holder 60. This allows the electrode portion 2a to be held by the insulating holder 60. The end portion of the electrode portion 2a that does not face the pressing block 2b is exposed and does not come into contact with the insulating holder 60. The held portion 2a1 may be, for example, cylindrical or prismatic. In the example shown in Fig. 5, the held portion 2a1 is cylindrical.

[0022] The exposed portion 2a2 is a portion of the electrode portion 2a that includes the end portion facing the pressing block 2b. As shown in FIG. 5, the exposed portion 2a2 is exposed to the outside of the insulating holder 60 of the electrode portion 2a. The exposed portion 2a2 may be, for example, cylindrical or prismatic. In the example shown in FIG. 5, the exposed portion 2a2 is cylindrical.

[0023] The intermediate portion 2a3 is a portion located between the held portion 2a1 and the exposed portion 2a2. As shown in FIG. 5, the intermediate portion 2a3 is located inside the insulating holder 60. The intermediate portion 2a3 may be, for example, cylindrical or prismatic. In the example shown in FIG. 5, the intermediate portion 2a3 is cylindrical.

[0024] Thus, electrode portion 2a has a shape in which three cylinders or prisms of different cross-sectional areas are integrally formed along the axial direction. Furthermore, the cross-sectional areas of these portions are smallest at held portion 2a1 and largest at exposed portion 2a2. Furthermore, the cross-sectional area of ​​intermediate portion 2a3 is larger than held portion 2a1 but smaller than exposed portion 2a2.

[0025] In this embodiment, the thickness of the two-electrode sensor 20 is thicker than the thickness of the superheater tube BP included in the boiler B. Hereinafter, in this embodiment, the thickness of the two-electrode sensor 20 (for example, the thickness of the first electrode unit 21) refers to the thickness of the electrode portion 2a included in the electrode unit (for example, the first electrode unit 21) of the two-electrode sensor 20. In addition, the thickness of the electrode portion 2a refers to the axial dimension of the cylindrical or prismatic shape of the above-mentioned held portion 2a1 included in the electrode portion 2a.

[0026] The pressing block 2b is a member located at the end of the electrode portion 2a on the exposed portion 2a2 side in the axial direction. In this embodiment, the pressing block 2b is a cylindrical or prismatic member having the same cross-sectional area as the exposed portion 2a2 of the electrode portion 2a. In the example shown in FIG. 5, the pressing block 2b has a cylindrical outer shape. In this embodiment, the pressing block 2b is preferably conductive and is preferably made of the same material as the electrode portion 2a, for example. As shown in Fig. 5, the pressing block 2b has a recess 2b1 that opens on the side facing the electrode portion 2a. Furthermore, as shown in Fig. 5, the pressing block 2b has a flat portion 2b2 on the side surface perpendicular to the axial direction of the electrode portion 2a, on which the conductor 40 and the conductor fixing plate 2d are provided. The flat portion 2b2 corresponds to the bottom of a groove formed in the side surface of the pressing block 2b, for example, as shown in Fig. 4. In other words, the flat portion 2b2 is formed by providing a groove in the side surface of the pressing block 2b.

[0027] 5, the pressing block 2b is fixed to the exposed portion 2a2 of the electrode portion 2a with a bolt BL. This forms a space between the pressing block 2b and the electrode portion 2a by a recess 2b1. An ultrasonic sensor 30 (i.e., a first ultrasonic sensor 31 described later) attached to the first electrode unit 21 is provided in this space.

[0028] In this embodiment, the general shape of the first electrode unit 21 is formed by an electrode portion 2a and a pressing block 2b. At this time, one end side of the first electrode unit 21 is located outside the tubular portion 10. Furthermore, the other end side of the first electrode unit 21 is located inside the tubular portion 10. That is, as shown in FIG. 3 , in the first electrode unit 21, the end of the electrode portion 2a that does not face the pressing block 2b is located outside the tubular portion 10. Furthermore, in the first electrode unit 21, the pressing block 2b is located inside the tubular portion 10. 5, a first through-hole 2H communicating with the electrode portion 2a and the pressing block 2b is provided in the first electrode unit 21 in a direction along the axial direction of the electrode portion 2a. A thermocouple 50 is provided in the first through-hole 2H.

[0029] FIG. 6 is a cross-sectional view taken along the line VI-VI shown in FIG. FIG. 7 is an enlarged view of part VII shown in FIG. 6, showing a first example of the sensor hold portion 2c. The sensor fixing portion 2c has a function of fixing the first ultrasonic sensor 31 to the first electrode unit 21. Specifically, the sensor fixing portion 2c fixes the first ultrasonic sensor 31 by pressing it against the end face of the exposed portion 2a2 of the electrode portion 2a of the first electrode unit 21. In this embodiment, the sensor holding portion 2c may be selected from any of the following three examples.

[0030] As shown in FIG. 7, the sensor fixture 2c according to the first example includes a fixing block 2c1, a fixing bolt 2c2, and a rod-shaped member 2c3. The fixing block 2c1 is a block-shaped member that contacts the first ultrasonic sensor 31. Specifically, the fixing block 2c1 contacts the side of the first ultrasonic sensor 31 that does not face the electrode portion 2a of the first electrode unit 21. In this way, the fixing block 2c1 sandwiches the first ultrasonic sensor 31 (ultrasonic sensor 30) between itself and a portion of the first electrode unit 21 on the other end side. Note that in this embodiment, the portion of the first electrode unit 21 on the other end side may be an end surface of the exposed portion 2a2 of the electrode portion 2a of the first electrode unit 21. Hereinafter, in this embodiment, the end surface of the exposed portion 2a2 will be referred to as the portion of the first electrode unit 21 on the other end side.

[0031] In this embodiment, the fixing block 2c1 is housed inside the space formed by the recess 2b1 of the pressing block 2b, as shown in FIG. Furthermore, fixing block 2c1 has notch 2c1a that opens in a direction perpendicular to the axial direction of held portion 2a1 and exposed portion 2a2 of electrode portion 2a. Fixing block 2c1 may also have recess 2c1b for receiving the tip of fixing bolt 2c2, which will be described next.

[0032] The fixing bolt 2c2 presses the fixing block 2c1 against the first ultrasonic sensor 31. When the two-electrode sensor 20 is attached to the tubular portion 10, the axial direction of the fixing bolt 2c2 is positioned approximately parallel to the direction perpendicular to the pipe axis of the tubular portion 10. Hereinafter, in this embodiment, "substantially parallel" means that the crossing angle between two straight lines is 5° or less.

[0033] 7, the fixing bolt 2c2 is threaded into a female threaded portion 2bS provided in the pressing block 2b and rotated, thereby enabling the fixing bolt 2c2 to move toward and away from the first ultrasonic sensor 31. The female threaded portion 2bS may be formed in a bushing or the like (not shown) that is a separate member from the pressing block 2b, and may be attached to the pressing block 2b. The fixing bolt 2c2 moves in a direction approaching the first ultrasonic sensor 31, thereby coming into contact with the fixing block 2c1, and then moves so as to press the fixing block 2c1 against the first ultrasonic sensor 31. As a result, the first ultrasonic sensor 31 is sandwiched and fixed between the electrode portion 2a and the fixing block 2c1.

[0034] The rod-shaped member 2c3 is a member whose longitudinal direction is positioned approximately parallel to the axial direction of the tubular portion 10 when the two-electrode sensor 20 is attached to the tubular portion 10. In this embodiment, the rod-shaped member 2c3 is a bolt, but is not limited to this. In other words, the rod-shaped member 2c3 may be a pin. As shown in Fig. 7, the rod-shaped member 2c3 is inserted into a second through-hole 2bH provided in the pressing block 2b. If the rod-shaped member 2c3 is a bolt, the second through-hole 2bH may have a female thread portion. If the rod-shaped member 2c3 is a pin, the second through-hole 2bH may not have a female thread portion. The relative position of the rod-shaped member 2c3 with respect to the fixing block 2c1 may be adjustable by moving along the second through-hole 2bH.

[0035] As shown in Fig. 7, the rod-shaped member 2c3 engages with a notch 2c1a provided in the fixing block 2c1. At this time, the ultrasonic sensor 30 is sandwiched between the other end side portion of the first electrode unit 21 (i.e., the end face of the exposed portion 2a2) and the rod-shaped member 2c3. That is, the ultrasonic sensor 30 is located between the other end side portion of the first electrode unit 21 and the rod-shaped member 2c3 in the axial direction of the cylindrical or prismatic shape of the held portion 2a1 of the electrode unit 2a. At this time, the ultrasonic sensor 30 does not need to be in contact with the rod-shaped member 2c3. Here, when the fixing bolt 2c2 rotates and the fixing block 2c1 is pressed against the first ultrasonic sensor 31, the fixing block 2c1 may rotate in conjunction with the rotation of the fixing bolt 2c2. This may cause the first ultrasonic sensor 31, which is in contact with the fixing block 2c1, to rotate. By positioning the rod-shaped member 2c3 as described above and engaging with the notch 2c1a of the fixing block 2c1, it is possible to restrict the rotation of the fixing block 2c1 that occurs with the rotation of the fixing bolt 2c2. This preferably allows the fixing block 2c1 to more reliably fix the first ultrasonic sensor 31 to the end face of the exposed portion 2a2.

[0036] FIG. 8 is a diagram showing a second example of the sensor holder 2c. As shown in FIG. 8, the sensor fixture 2c according to the second example includes a second fixing block 2c4 and an elastic member 2c5. The second fixing block 2c4 differs from the fixing block 2c1 according to the first example only in that it does not have the notch 2c1a. The elastic member 2c5 presses the second fixing block 2c4 against the first ultrasonic sensor 31 by its elastic force. In the sensor fixing portion 2c according to the second example, the elastic member 2c5 is a known ball plunger. For example, as shown in FIG. 8, the elastic member 2c5 may be provided in a third through-hole 2bS1 provided in the pressing block 2b. When the two-electrode sensor 20 is attached to the tubular portion 10, the longitudinal direction of the elastic member 2c5 is positioned approximately parallel to the direction perpendicular to the tube axis of the tubular portion 10. In the sensor fixing portion 2c according to the second example, the ultrasonic sensor 30 is sandwiched between a portion of the first electrode unit 21 on the other end side (i.e., the end face of the exposed portion 2a2), the elastic member 2c5, and the second fixing block 2c4, as shown in FIG.

[0037] FIG. 9 is a diagram showing a third example of the sensor holder 2c. The sensor fixture 2c according to the third example includes a second fixing block 2c4 and a biasing member 2c6. The second fixed block 2c4 has the same configuration as in the second example, and therefore a description thereof will be omitted. The biasing member 2c6 includes a biasing bolt 2c6a and a biasing spring 2c6b. The biasing bolt 2c6a is threadedly engaged with a female threaded portion 2bS provided on the pressing block 2b and rotates, thereby being able to move towards and away from the first ultrasonic sensor 31. When the tip of the biasing bolt 2c6a approaches the first ultrasonic sensor 31, it presses the biasing spring 2c6b towards the second fixed block 2c4. The biasing spring 2c6b is a known coil spring. When the two-electrode sensor 20 is attached to the tubular portion 10, the axial direction of the biasing spring 2c6b is positioned approximately parallel to the direction perpendicular to the tube axis of the tubular portion 10. The biasing spring 2c6b is pressed against the second fixing block 2c4 by the biasing bolt 2c6a, and generates an elastic force that presses the second fixing block 2c4 against the ultrasonic sensor 30. That is, in the sensor fixing portion 2c of the third example, the ultrasonic sensor 30 is urged by the urging member 2c6 via the second fixing block 2c4 toward the portion of the first electrode unit 21 on the other end side (i.e., the end face of the exposed portion 2a2), as shown in FIG.

[0038] The conductor fixing plate 2d is a flat member provided for fixing the conductor 40 to the pressing block 2b. As shown in Fig. 5, the conductor fixing plate 2d is fixed to the pressing block 2b with a countersunk bolt CB, with the conductor 40 sandwiched between the conductor fixing plate 2d and the flat portion 2b2 of the pressing block 2b.

[0039] The second electrode unit 22, the third electrode unit 23, and the fourth electrode unit 24 each have a configuration similar to that of the first electrode unit 21. That is, the second electrode unit 22, the third electrode unit 23, and the fourth electrode unit 24 each have an electrode portion 2a, a pressing block 2b, a sensor fixing portion 2c, and a conductor fixing plate 2d. Like the first electrode unit 21, one end side of each of the second electrode unit 22, the third electrode unit 23, and the fourth electrode unit 24 (i.e., the electrode portion 2a side) is located outside the tubular portion 10, and the other end side (i.e., the pressing block 2b side) is located inside the tubular portion 10.

[0040] In this embodiment, the thicknesses of the first electrode unit 21, the second electrode unit 22, the third electrode unit 23, and the fourth electrode unit 24 may be different from one another. That is, in this embodiment, the first electrode unit 21, the second electrode unit 22, the third electrode unit 23, and the fourth electrode unit 24 may be identical in other respects, except for the thickness of the electrode portions 2a. Note that when the thicknesses of these electrode units (i.e., the thicknesses of the electrode portions 2a included in each electrode unit) are different from one another, for example, the first electrode unit 21 may be the thickest, followed by the second electrode unit 22, the third electrode unit 23, and the fourth electrode unit 24 in that order, with the fourth electrode unit 24 being the thinnest.

[0041] In the present embodiment, the first electrode unit 21, the second electrode unit 22, the third electrode unit 23, and the fourth electrode unit 24 are arranged close to one another. That is, for example, as shown in FIGS. 4 and 6 , in the circumferential direction of the tubular portion 10, the first electrode units 21 and the third electrode units 23 are arranged concentratedly on one side of the tubular portion 10 in the direction perpendicular to the tube axis. The second electrode units 22 and the fourth electrode units 24 are arranged in a similar manner. In addition, in the tube axis direction of the tubular portion 10, the first electrode units 21 and the second electrode units 22, and the third electrode units 23 and the fourth electrode units 24 may be positioned at intervals equal to the intervals between the first electrode unit 21 and the third electrode unit 23 or the intervals between the second electrode unit 22 and the fourth electrode unit 24 in the circumferential direction.

[0042] As a result, when performing electrochemical measurement using the two-electrode sensor 20, the working electrode and counter electrode can be any of the following combinations: the first electrode unit 21 and the second electrode unit 22, the first electrode unit 21 and the third electrode unit 23, the first electrode unit 21 and the fourth electrode unit 24, the second electrode unit 22 and the third electrode unit 23, the second electrode unit 22 and the fourth electrode unit 24, and the third electrode unit 23 and the fourth electrode unit 24. Therefore, the detection range for electrochemical measurement can be wider than, for example, a two-electrode sensor in which electrodes cannot be switched.

[0043] In this embodiment, the distance between the electrodes arranged close to each other is, for example, 0.5 mm at their closest points. Specifically, the distance between the exposed portions 2a2 of the electrode portions 2a of each electrode and the distance between the pressing blocks 2b are 0.5 mm. In this case, the distance between the held portions 2a1 of the electrode portions 2a of each electrode may be, for example, 3 mm.

[0044] The ultrasonic sensor 30 measures the thickness of the electrodes of the two-electrode sensor 20. That is, the ultrasonic sensor 30 measures the thickness of the electrode portion 2a included in each electrode unit of the two-electrode sensor 20 by using reflected ultrasonic waves. In this embodiment, a known piezoelectric element is preferably used for the ultrasonic sensor 30. In this embodiment, the ultrasonic sensor 30 is disposed by being deposited on each portion of the electrode unit of the two-electrode sensor 20, that is, on the other end side of each electrode unit (i.e., the end face of the exposed portion 2a2 of the electrode portion 2a). Hereinafter, depositing the ultrasonic sensor 30 on the electrode portion 2a of the two-electrode sensor 20 will be referred to as "the ultrasonic sensor 30 is disposed."

[0045] 4, the ultrasonic sensor 30 includes a first ultrasonic sensor 31, a second ultrasonic sensor 32, a third ultrasonic sensor 33, and a fourth ultrasonic sensor 34. Note that these ultrasonic sensors 30 all have the same configuration, but are equipped with different electrode units. Hereinafter, when there is no need to distinguish between the first ultrasonic sensor 31, the second ultrasonic sensor 32, the third ultrasonic sensor 33, and the fourth ultrasonic sensor 34, they will be referred to as ultrasonic sensors 30.

[0046] The first ultrasonic sensor 31 measures the thickness of the first electrode unit 21. As shown in Fig. 3 or 5, the first ultrasonic sensor 31 is disposed in a portion of the first electrode unit 21 on the other end side of the first electrode unit 21. The second ultrasonic sensor 32 measures the thickness of the second electrode unit 22. As shown in Fig. 3, the second ultrasonic sensor 32 is disposed in a portion of the second electrode unit 22 on the other end side of the second electrode unit 22.

[0047] The third ultrasonic sensor 33 measures the thickness of the third electrode unit 23. Similar to the first ultrasonic sensor 31 and the second ultrasonic sensor 32, the third ultrasonic sensor 33 is disposed in a portion of the third electrode unit 23 on the other end side of the third electrode unit 23. The fourth ultrasonic sensor 34 measures the thickness of the fourth electrode unit 24. Like the first ultrasonic sensor 31 and the second ultrasonic sensor 32, the fourth ultrasonic sensor 34 is disposed in a portion of the fourth electrode unit 24 on the other end side of the fourth electrode unit 24.

[0048] The conductor 40 transmits, for example, a measurement signal from the two-electrode sensor 20 or a measurement signal from the ultrasonic sensor 30. As shown in FIG. 3 or 5, the conductor 40 is in contact with the pressing block 2b of the first electrode unit 21 and the pressing block 2b of the second electrode unit 22. As described above, the pressing block 2b is conductive, and therefore the conductor 40 and the pressing block 2b are in contact with each other and are therefore electrically connected. The conductor 40 is also electrically connected to the electrode portion 2a via the pressing block 2b. In this embodiment, the conductor 40 is an outer conductor 82 of a cable 80, which will be described later. In this embodiment, the longitudinal direction of the conductor 40 is approximately parallel to the direction perpendicular to the tube axis of the tubular portion 10 when the two-electrode sensor 20 is attached to the tubular portion 10. Furthermore, as shown in Fig. 5, the conductor 40 is fixed to the flat portion 2b2 of the pressing block 2b provided in each electrode unit of the two-electrode sensor 20 by a conductor fixing plate 2d.

[0049] The conducting wire 41 is connected to the ultrasonic sensor 30 by being pressed against the ultrasonic sensor 30 attached to the electrode portion 2a of the electrode unit (for example, the first electrode unit 21) by a fixing block 2c1, as shown in FIG. 5, for example. In this embodiment, the conductor 41 is an inner conductor 81 of a cable 80, which will be described later. The conductor 40 and the lead wire 41 are also connected to the third ultrasonic sensor 33 and the fourth ultrasonic sensor 34 in the same manner.

[0050] The thermocouple 50 is provided, for example, to measure the temperature of each of the electrode units of the two-electrode sensor 20. Information on the temperature measured by the thermocouple 50 is used, for example, to perform sound speed correction on the measured value of the wall thickness of the electrode portion 2 a measured by the ultrasonic sensor 30. Here, when measuring the thickness of the electrode portion 2a of the two-electrode sensor 20 using the ultrasonic sensor 30, if the temperature of the electrode portion 2a changes due to the influence of the temperature at the installation location of the monitoring probe 1, the speed at which the ultrasonic waves propagate inside the electrode portion 2a changes, which may change the measurement result of the thickness of the electrode portion 2a measured by the ultrasonic sensor 30. Therefore, by detecting the temperature of each of the electrode portions 2a of the two-electrode sensor 20 using the thermocouple 50, the measurement result of the thickness by the ultrasonic sensor 30 can be corrected as appropriate.

[0051] Furthermore, if the two-electrode sensor 20 is placed in a high-temperature environment, the electrode portion 2a of the two-electrode sensor 20 will thermally expand. This will cause the thickness of the electrode portion 2a to change, which may change the measurement result of the thickness of the electrode portion 2a measured by the ultrasonic sensor 30. Therefore, in order to make a fair comparison with the thickness of the electrode portion 2a at room temperature, the information on the temperature measured by the thermocouple 50 may be used, for example, to correct for the effects of thermal expansion of the tubular portion 10 and the electrode portion 2a of the two-electrode sensor 20.

[0052] In this embodiment, one thermocouple 50 is provided for each ultrasonic sensor 30. That is, at least four thermocouples 50 are provided corresponding to the four ultrasonic sensors 30 described above, namely, the first ultrasonic sensor 31, the second ultrasonic sensor 32, the third ultrasonic sensor 33, and the fourth ultrasonic sensor 34. This preferably enables the measurement results of each of these ultrasonic sensors 30 to be corrected individually. 5, the thermocouples 50 are provided by arranging their tips in the first through-holes 2H of the electrode portion 2a and the pressing block 2b of each of the electrode units of the two-electrode sensor 20. In this way, the thermocouples 50 measure the temperature of the two-electrode sensor 20.

[0053] The thermocouple 50 may also be provided to measure the temperature of the air inside the tubular portion 10. Hereinafter, among the thermocouples 50, one that measures the temperature of the air inside the tubular portion 10 will be referred to as an air temperature measuring thermocouple 51. The air temperature measuring thermocouple 51 has its tip positioned in the internal space of the tubular portion 10 to measure the temperature of the air inside the tubular portion 10. In this embodiment, the air temperature measuring thermocouples 51 are provided at three locations inside the tubular portion 10. Specifically, as shown in FIGS. 2 and 3 , one air temperature measuring thermocouple 51 is provided near the location where the two-electrode sensor 20 is installed in the tubular portion 10, and two are provided in the middle portion 2a3 of the tubular portion 10.

[0054] The insulating holder 60 is provided to hold the two-electrode sensor 20 while insulating the two-electrode sensor 20 from the tubular portion 10. This contributes to more accurate electrochemical measurements using the two-electrode sensor 20. In this embodiment, the insulating holder 60 is preferably made of, for example, ceramic.

[0055] In this embodiment, the insulating holder 60 is preferably cylindrical. By making the insulating holder 60 cylindrical, stress concentration is less likely to occur, which makes it easier to prevent the ceramic forming the insulating holder 60 from being damaged.

[0056] In this embodiment, one insulating holder 60 is provided for each ultrasonic sensor 30. That is, an insulating holder 60 is provided for each of the first electrode unit 21, second electrode unit 22, third electrode unit 23, and fourth electrode unit 24 to which the ultrasonic sensor 30 is attached. Therefore, in this embodiment, the monitoring probe 1 includes four insulating holders 60.

[0057] As described above, the four electrode units are close to each other. Therefore, the four insulating holders 60 are also close to each other. In this embodiment, the insulating holders 60 do not necessarily have to be in contact with each other. The following description will be given taking the first electrode unit 21 as an example, but the same applies to the other electrode units.

[0058] 5, the cylindrical insulating holder 60 accommodates the held portion 2a1 and the intermediate portion 2a3 of the electrode portion 2a of the first electrode unit 21. At this time, in the radial direction of the electrode portion 2a, the exposed portion 2a2 is not positioned outside the outer circumferential edge of the insulating holder 60. As described above, the thermocouple 50 is disposed in the electrode portion 2a of the first electrode unit 21 and the first through-hole 2H of the pressing block 2b.

[0059] Therefore, when the first electrode unit 21 is attached to the tubular portion 10, the first electrode unit 21 and the thermocouple 50 are located inside the insulating holder 60 when viewed in the direction perpendicular to the tube axis of the tubular portion 10. In addition, the first ultrasonic sensor 31 provided in the first electrode unit 21 is also located inside the insulating holder 60 when viewed in the direction perpendicular to the tube axis of the tubular portion 10.

[0060] The metal holder 70 is located between the tubular portion 10 and the insulating holder 60. As shown in FIG. 6, the metal holder 70 is a cylindrical member that houses the insulating holder 60 therein. In this embodiment, the metal holder 70 houses all four insulating holders 60 provided in the monitoring probe 1 as described above. In this way, the metal holder 70 may have the function of positioning the four insulating holders 60 relative to each other.

[0061] In this embodiment, the metal holder 70 is fixed to the tubular portion 10 by, for example, welding. In this way, each of the electrode units of the two-electrode sensor 20 is attached to the tubular portion 10 via the insulating holder 60 and the metal holder 70. With the two-electrode sensor 20 attached to the tubular portion 10 in this manner, the insulating holder 60 is located inside the metal holder 70 when viewed in a direction perpendicular to the tube axis of the tubular portion 10. 6, one end of the two-electrode sensor 20 protrudes from the metal holder 70. That is, the end of the electrode portion 2a of the two-electrode sensor 20 (for example, the first electrode unit 21) that does not face the pressing block 2b protrudes from the metal holder 70.

[0062] The cable 80 is disposed inside the tubular portion 10 and transmits the measurement signals of the ultrasonic sensor 30 and the two-electrode sensor 20 to the receiving device 90. That is, the cable 80 transmits the measurement signals of the thickness of the electrode portion 2a measured by the ultrasonic sensor 30 and the measurement signals of the electrochemical measurement by the two-electrode sensor 20 from the ultrasonic sensor 30 and the two-electrode sensor 20, respectively, to the receiving device 90.

[0063] FIG. 10 is a first schematic diagram showing the connection of a combination of an ultrasonic sensor 30 and an electrode unit of a two-electrode sensor 20 to a receiving device 90 via a cable 80 and a switch A. In this embodiment, a known coaxial cable is preferably used for the cable 80. As shown in Fig. 10, the coaxial cable has an inner conductor 81 and an outer conductor 82 that are insulated from each other. In the example shown in Fig. 10, the inner conductor 81 of the cable 80 is indicated only by a solid line, and the outer conductor 82 is indicated by a cylinder positioned around the solid line indicating the inner conductor 81 and a solid line connected to the cylinder. As described above, the inner conductor 81 is the conductor 41 shown in Fig. 5, and the outer conductor 82 is the conductor 40 shown in Fig. 5.

[0064] 10, only the combination of the first electrode unit 21 and the first ultrasonic sensor 31 and the combination of the second electrode unit 22 and the second ultrasonic sensor 32 are shown schematically, but the combination of the third electrode unit 23 and the third ultrasonic sensor 33 and the combination of the fourth electrode unit 24 and the fourth ultrasonic sensor 34 have similar configurations. In the following description, the combination of the first electrode unit 21 and the first ultrasonic sensor 31 may be referred to as a first set P1, the combination of the second electrode unit 22 and the second ultrasonic sensor 32 as a second set P2, the combination of the third electrode unit 23 and the third ultrasonic sensor 33 as a third set, and the combination of the fourth electrode unit 24 and the fourth ultrasonic sensor 34 as a fourth set. In the following description of the connection structure of the cable 80, the connection between the cable 80 and the first set P1 will be described, but the same applies to the other combinations of electrode units and ultrasonic sensors 30.

[0065] In this embodiment, as shown in FIG. 10, the inner conductor 81 of the cable 80 is connected to the ultrasonic sensor 30 (for example, the first ultrasonic sensor 31), and the outer conductor 82 is connected to the electrode unit (for example, the first electrode unit 21).

[0066] This allows, for example, the inner conductor 81 of the cable 80 to be used as a positive electrode for transmitting the measurement signal of the ultrasonic sensor 30 to the receiving device 90, and the outer conductor 82 to be used as a negative electrode which is the return path for the measurement signal of the ultrasonic sensor 30. Furthermore, by connecting the outer conductor 82 of the cable 80 to the electrode unit or the pressing block 2b, it is also possible to transmit the measurement signal of the two-electrode sensor 20 to the receiving device 90 via the outer conductor 82. In this embodiment, whether the outer conductor 82 of the cable 80 is used as a return path for the measurement signal of the ultrasonic sensor 30 or for transmitting the measurement signal of the two-electrode sensor 20 to the receiving device 90 is switched by a switch A (details will be described later).

[0067] One cable 80 is provided for each ultrasonic sensor 30. In this embodiment, one end of the cable 80 is connected to the conductor 40 that is connected to the first ultrasonic sensor 31 and the second ultrasonic sensor 32, for example, as shown in Fig. 3 and Fig. 5 . The same is true for the third ultrasonic sensor 33 and the fourth ultrasonic sensor 34. Thus, in this embodiment, four cables 80 are arranged inside the tubular portion 10, as shown in Fig. 6 .

[0068] 3 and 6, in this embodiment, the cable 80 is positioned on the opposite side of the ultrasonic sensor 30 across the tube axis of the tubular portion 10. This preferably makes it easier for the hot air used to adjust the temperature of the electrodes of the two-electrode sensor 20 and recreate a corrosive environment to hit the electrodes.

[0069] The receiving device 90 receives the measurement signal of the ultrasonic sensor 30 and the measurement signal of the two-electrode sensor 20. For this purpose, one end of the cable 80, the other end of which is connected to the conductor 40 as described above, is connected to the receiving device 90 via the switch A. In this embodiment, the receiving device 90 includes a first processing device 91 and a second processing device 92.

[0070] The first processing device 91 is a part of the receiving device 90 that receives and processes the measurement signal from the ultrasonic sensor 30. In this embodiment, the first processing device 91 is a known pulser receiver (ultrasonic thickness measuring device). That is, the first processing device 91 causes the ultrasonic sensor 30 to emit ultrasonic waves via the cable 80 to measure the thickness of the electrode portion 2a. The first processing device 91 then receives, via the cable 80, the reflected waves of the ultrasonic waves received by the ultrasonic sensor 30. In this way, the first processing device 91 measures the thickness of the electrode portion 2a. The first processing device 91 may also appropriately correct the measurement result of the thickness of the electrode portion 2a based on the temperature of the electrode unit measured by a thermocouple 50 provided in the electrode unit. In this embodiment, a first processing device 91 that receives and processes the measurement signal of the ultrasonic sensor 30 may be installed at the base of the tubular section 10. Specifically, as shown in FIG. 1 , the first processing device 91 may be provided at the end of the tubular section 10 on the side of the connection with the boiler B. This reduces the distance between the electrode unit and the ultrasonic sensor 30 and the first processing device 91 while suppressing the first processing device 91 from being affected by the heat of the boiler B. Furthermore, as shown in FIG. 1 , the first processing device 91 may be disposed inside a dustproof box DB attached to the base of the tubular section 10 via a purge pipe P. The first processing device 91 may be connected to a switch A via a cable 80.

[0071] The second processing device 92 is a part of the receiving device 90 that receives and processes the measurement signal of the two-electrode sensor 20. In this embodiment, the second processing device 92 is a known potentiostat (electrochemical measurement device). That is, the second processing device 92 performs electrochemical measurement using two of the first electrode unit 21, the second electrode unit 22, the third electrode unit 23, and the fourth electrode unit 24 as a combination of a working electrode and a counter electrode. In this embodiment, the second processing device 92 does not have to be installed at the base of the tubular portion 10. In this case, the second processing device 92 may be disposed outside the dustproof box DB, as shown in Fig. 1. The second processing device 92 may be connected to the switch A via a cable 80.

[0072] The switch A is a switch that switches the signal transmitted by the cable 80 from one of the first processing device 91 and the second processing device 92 to the other. In this embodiment, the switch A is installed at the base of the tubular section 10. Specifically, the switch A may be arranged, together with the first processing device 91 of the receiving device 90, in a dustproof box DB connected to the end of the base side of the tubular section 10. In this embodiment, the switch A is arranged inside the dustproof box DB, as shown in FIG. 1.

[0073] The switching of the signal transmitted by the cable 80 by the switch A may be performed, for example, by a user of the monitoring probe 1 as appropriate, or may be performed automatically over time, etc. In this embodiment, a known coaxial switch is preferably used as the switch A.

[0074] The following describes how the switch A switches the signal transmitted by the cable 80 from one of the first processing device 91 and the second processing device 92 to the other. Note that the following description will be given using the cable 80 and the switch A connected to the first set P1 and the second set P2, respectively, but the same applies to the third and fourth sets.

[0075] In this embodiment, as shown in Fig. 10, one switch A is provided for one cable 80. Furthermore, one switch A includes a first mechanical relay A1 and a second mechanical relay A2. The first mechanical relay A1 is connected to an inner conductor 81 of the cable 80, which is connected to the ultrasonic sensor 30. The first mechanical relay A1 switches whether or not to transmit the measurement signal of the ultrasonic sensor 30 transmitted by the inner conductor 81 to the first processing device 91. In the example shown in FIG. 10, both of the first mechanical relays A1 corresponding to the first group P1 and the second group P2 are in a state in which they transmit the electrical signal transmitted by the inner conductor 81 (the measurement signal of the ultrasonic sensor 30) to the first processing device 91. When the first mechanical relay A1 does not transmit the measurement signal of the ultrasonic sensor 30 to the first processing device 91, the inner conductor 81 is in an insulated state.

[0076] The second mechanical relay A2 is connected to an outer conductor 82 of the cable 80, which is connected to the electrode unit. The second mechanical relay A2 switches between transmitting the electrical signal transmitted by the outer conductor 82 to the first processing device 91 or the second processing device 92. In the example shown in FIG. 10 , both the second mechanical relays A2 corresponding to the first group P1 and the second group P2 are in a state of transmitting the electrical signal transmitted by the outer conductor 82 to the first processing device 91.

[0077] 10, in order to cope with the case where the second mechanical relay A2 is set to a state in which it transmits the electrical signal transmitted by the outer conductor 82 to the second processing device 92, an auxiliary cable 80a different from the cable 80 may be provided between each of the second mechanical relays A2 and the second processing device 92. The auxiliary cable 80a may be a known coaxial cable. The inner conductor 81 of the auxiliary cable 80a may be connected to, for example, the side of the first mechanical relay A1 that does not transmit the measurement signal of the ultrasonic sensor 30 to the first processing device 91, and may be insulated. In addition, the outer conductor 82 of the auxiliary cable 80a may connect the second mechanical relay A2 and the second processing device 92.

[0078] 10, in the cables 80 connected to the first group P1 and the second group P2, both the inner conductor 81 and the outer conductor 82 are connected to the first processing device 91. This allows the thickness of the electrode portion 2a to be measured using the ultrasonic sensor 30 in both the first group P1 and the second group P2. 10, the inner conductor 81 of the cable 80 connected to the first set P1 is connected to the pulse generator 91a of the first processing device 91 by a mechanical relay included in the first processing device 91. Therefore, in the example shown in Fig. 10, it is possible to measure the thickness of the electrode portion 2a of the first electrode unit 21 using the first ultrasonic sensor 31 in the first set P1.

[0079] FIG. 11 is a second schematic diagram showing the connection of a combination of the ultrasonic sensor 30 and the electrode unit of the two-electrode sensor 20 to a receiving device 90 via a cable 80 and a switch A. 11 differs from the example shown in Fig. 10 in that each of the second mechanical relays A2 corresponding to the first group P1 and the second group P2 is in a state in which it transmits the electrical signal transmitted by the outer conductor 82 to the second processing device 92. Note that in Fig. 11, the first mechanical relays A1 corresponding to the first group P1 and the second group P2 are in a state in which it transmits the electrical signal transmitted by the inner conductor 81 (measurement signal of the ultrasonic sensor 30) to the first processing device 91, but may be in a state in which it does not transmit the electrical signal to the first processing device 91.

[0080] In the example shown in Figure 11, in the circuit in which the thickness of the electrode portion 2a of the first group P1 and the second group P2 is measured using the ultrasonic sensor 30, the negative side of the switch A is insulated, and both of the outer conductors 82 of the cables 80 connected to each of the first group P1 and the second group P2 are connected to the second processing device 92. This allows the first electrode unit 21 of the first set P1 and the second electrode unit 22 of the second set P2 to be used as either the working electrode or the counter electrode of the two-electrode sensor 20, making it possible to perform electrochemical measurements.

[0081] As described above, the switch A can switch the signal transmitted by the cable 80 from one of the first processing device 91 and the second processing device 92 to the other. By switching the destination of the signal transmitted by the cable 80 in this manner, for example, by appropriately selecting two of the four electrode units from the first electrode unit 21 of the first set P1 to the fourth electrode unit 24 of the fourth set P2 and connecting them to the second processing device 92, two of these electrode units can function appropriately as the two-electrode sensor 20.

[0082] For example, electrochemical measurement can be performed using the first electrode unit 21 and the third electrode unit 23 by setting the second mechanical relays A2 connected to the first electrode unit 21 and the third electrode unit 23, respectively, to a state in which they transmit the electrical signal transmitted by the external conductor 82 to the second processing device 92, and setting the second mechanical relays A2 connected to the second electrode unit 22 and the fourth electrode unit 24, respectively, to a state in which they do not transmit the electrical signal transmitted by the external conductor 82 to the second processing device 92. At this time, the first mechanical relays A1 connected to the first electrode unit 21 and the third electrode unit 23, respectively, may be set to a state in which they do not transmit the electrical signal transmitted by the internal conductor 81 to the first processing device 91.

[0083] Here, for example, if each switch A does not have the second mechanical relay A2, the auxiliary cable 80a described above cannot be provided. As a result, the outer conductor 82 of the cable 80 is connected to both the first processing device 91 and the second processing device 92 at the same time. As a result, the outer conductor 82 is electrically short-circuited, and electrochemical measurement by the second processing device 92 cannot be performed. The switch A is equipped with a second mechanical relay A2, and by insulating the negative side of the circuit that measures the thickness of the electrode portion 2a using the ultrasonic sensor 30, the above problems are prevented from occurring, and electrochemical measurements are made possible using the second processing device 92.

[0084] The monitoring probe 1 according to this embodiment is configured as described above. In this embodiment, the cable 80 may be temporarily connectable to a ground (not shown), which may allow the electric charge accumulated in the circuit including the cable 80 to be discharged, thereby reducing noise in the thickness measurement and electrochemical measurement of the electrode portion 2 a of the two-electrode sensor 20. The connection circuit of the cable 80 may be provided with a transformer (not shown) for suppressing noise.

[0085] As described above, in the monitoring probe 1 according to this embodiment, one end side (i.e., the electrode portion 2a side) of the electrode unit included in the two-electrode sensor 20 is located outside the tubular portion 10, and the other end side (i.e., the pressing block 2b side) of the electrode unit is located inside the tubular portion 10. The ultrasonic sensor 30 is disposed in the other end side of the electrode unit (i.e., the end face of the exposed portion 2a2 of the electrode portion 2a in the electrode unit). In other words, the electrode unit of the two-electrode sensor 20 and the ultrasonic sensor 30 are disposed so as to overlap in the direction perpendicular to the tube axis of the tubular portion 10.

[0086] This makes it possible to reduce the area occupied in the axial direction of the tubular portion 10 compared to when, for example, the electrode unit of the two-electrode sensor 20 and the ultrasonic sensor 30 are positioned so as not to overlap in the direction perpendicular to the axial direction of the tubular portion 10 (so as to be aligned in the axial direction of the tubular portion 10). Therefore, making it easier to shorten the axial length of the tubular portion 10 can contribute to miniaturizing the monitoring probe 1 in the axial direction of the tubular portion 10.

[0087] Furthermore, by arranging the electrode unit of the two-electrode sensor 20 and the ultrasonic sensor 30 so as to overlap in the direction perpendicular to the tube axis of the tubular portion 10, the electrode portion 2a of the electrode unit of the two-electrode sensor 20 can be used as the target for measuring the wall thickness by the ultrasonic sensor 30. This reduces the need to secure an area for measuring the wall thickness of the tubular portion 10 with the ultrasonic sensor 30, and allows the tubular portion 10 to be shortened. This also contributes to the miniaturization of the monitoring probe 1 in the tube axis direction of the tubular portion 10.

[0088] The two-electrode sensor 20 is used for electrochemical measurement. The ultrasonic sensor 30 measures the thickness of the electrodes included in the two-electrode sensor 20 (i.e., the thickness of the electrode portion 2a). This allows the electrochemical measurement by the two-electrode sensor 20 and the measurement of the thickness of the electrode portion 2a of the two-electrode sensor 20 by the ultrasonic sensor 30 to be performed at the same location on the tubular portion 10.

[0089] Depending on the environment of the installation location of the monitoring probe 1 (for example, inside the boiler B or a furnace), an oxide film may form on the outer peripheral surface of the tubular portion 10. In this case, when the thickness of the tubular portion 10 is measured using the ultrasonic sensor 30, the ultrasonic waves emitted by the ultrasonic sensor 30 during measurement are reflected by the oxide film, and therefore, if the measured value of the wall thickness changes, it becomes unclear whether the change in the measurement value is due to an actual change in the wall thickness of the tubular portion 10 or the influence of the oxide film.

[0090] By performing electrochemical measurement by the two-electrode sensor 20 and measurement of the electrode thickness of the two-electrode sensor 20 by the ultrasonic sensor 30 at the same location on the tubular portion 10, it is possible to determine from the impedance of the electrode unit whether an oxide film has formed on the electrode portion 2a of the two-electrode sensor 20 during electrochemical measurement by the two-electrode sensor 20, while measuring the thickness of the electrode portion 2a of the two-electrode sensor 20 by the ultrasonic sensor 30. Therefore, in addition to being able to accurately measure changes in the thickness of the electrode portion 2a of the two-electrode sensor 20, it is also possible to easily grasp the corrosion status of the location where the monitoring probe 1 is installed.

[0091] Furthermore, according to the monitoring probe 1 described above, the longitudinal direction of the conductor 40 for transmitting the measurement signal of the ultrasonic sensor 30 is approximately parallel to the direction perpendicular to the tube axis of the tubular portion 10. This makes it easier to reduce the size of the area in which the conductor 40 is located in the tube axis direction of the tubular portion 10. Therefore, it is possible to more reliably reduce the size of the monitoring probe 1 in the tube axis direction of the tubular portion 10.

[0092] The two-electrode sensor 20 includes a first electrode unit 21, a second electrode unit 22, a third electrode unit 23, and a fourth electrode unit 24. The two-electrode sensor 20 functions by combining any two of these electrode units. For example, if a two-electrode sensor has two electrodes connected together in a non-switchable circuit, electrochemical measurement can be performed only in the area between the two electrodes. In contrast, the two-electrode sensor 20 functions by combining two of a plurality of individually provided electrode units, which allows the area between the two electrode units to be larger. This allows for a wider detection area for electrochemical measurement. Furthermore, these electrode units are arranged close to each other, which allows the monitoring probe 1 to be made smaller in size in the axial direction of the tubular portion 10.

[0093] The monitoring probe 1 further includes a thermocouple 50 and an insulating holder 60. By including the thermocouple 50, for example, the measurement result of the thickness of the electrode portion 2 a of the two-electrode sensor 20 by the ultrasonic sensor 30 can be corrected for sound speed. Also, the influence of thermal expansion of the tubular portion 10 and the two-electrode sensor 20 can be corrected. Therefore, the accuracy of the measurement of the thickness of the electrode portion 2 a of the two-electrode sensor 20 by the ultrasonic sensor 30 can be improved. Furthermore, by providing the insulating holder 60, for example, the electrode unit of the two-electrode sensor 20 can be insulated from the tubular portion 10. Therefore, by facilitating reliable measurement of current by the electrode unit of the two-electrode sensor 20, the accuracy of electrochemical measurement by the two-electrode sensor 20 can be improved. Therefore, it is possible to easily grasp the corrosion state of the installation location of the monitoring probe 1 by electrochemical measurement by the two-electrode sensor 20.

[0094] Furthermore, the electrode unit of the two-electrode sensor 20 and the thermocouple 50 are located inside the insulating holder 60 when viewed in the direction perpendicular to the tube axis of the tubular portion 10. This makes it possible to reduce the area occupied by the electrode unit of the two-electrode sensor 20, the thermocouple 50, and the insulating holder 60 in the tube axis direction of the tubular portion 10. This makes it possible to more reliably reduce the size of the monitoring probe 1 in the tube axis direction of the tubular portion 10.

[0095] Furthermore, the ultrasonic sensor 30 is positioned inside the insulating holder 60 when viewed in the direction perpendicular to the tube axis of the tubular portion 10. As a result, the ultrasonic sensor 30 is positioned so as to overlap the electrode unit of the two-electrode sensor 20 when viewed in the direction perpendicular to the tube axis of the tubular portion 10. This improves the accuracy of measurement of the wall thickness of the electrode unit of the two-electrode sensor 20 by the ultrasonic sensor 30. Furthermore, the area occupied by the electrode unit of the two-electrode sensor 20, the thermocouple 50, the insulating holder 60, and the ultrasonic sensor 30 in the tube axis direction of the tubular portion 10 can be reduced. This makes it possible to more reliably reduce the size of the monitoring probe 1 in the tube axis direction of the tubular portion 10.

[0096] Furthermore, one thermocouple 50 and one insulating holder 60 are provided for each ultrasonic sensor 30. This allows, for example, when multiple ultrasonic sensors 30 are provided, individual sound speed correction to be performed on the measurement results of the thickness of the electrode portion 2a of the two-electrode sensor 20 measured by one ultrasonic sensor 30. Furthermore, the effects of thermal expansion of the tubular portion 10 and the two-electrode sensor 20 can be corrected more precisely. This further improves the accuracy of measurement of the thickness of the electrode portion 2a of the two-electrode sensor 20 by the ultrasonic sensors 30.

[0097] Furthermore, the metal holder 70 is positioned between the tubular portion 10 and the insulating holder 60. The insulating holder 60 is positioned inside the metal holder 70 when viewed in a direction perpendicular to the tube axis of the tubular portion 10. This makes it easier to position the insulating holder 60 relative to the tubular portion 10.

[0098] Furthermore, one end of the electrode unit of the two-electrode sensor 20 (i.e., the end of the electrode portion 2a that does not face the pressing block 2b) protrudes from the metal holder 70. This makes it easier to prevent, for example, high-temperature molten salt of ash from adhering between the metal holder 70 and one end of the electrode unit of the two-electrode sensor 20, causing electrical conduction between the metal holder 70 and the electrode unit and making electrochemical measurement impossible. This makes it easier to reliably measure current using the electrode unit. Therefore, it is easier to understand the corrosion status of the installation location of the monitoring probe 1 through electrochemical measurement by the two-electrode sensor 20.

[0099] Additionally, the ultrasonic sensor 30 is sandwiched between the fixing block 2c1 and the other end of the electrode unit of the two-electrode sensor 20 (i.e., the end face of the exposed portion 2a2 of the electrode portion 2a of the electrode unit). Additionally, the fixing bolt 2c2 presses the fixing block 2c1 against the ultrasonic sensor 30. This allows the ultrasonic sensor 30 to be fixed by pressing it against the end face of the exposed portion 2a2 of the electrode portion 2a of the electrode unit.

[0100] Furthermore, the axial direction of the fixing bolt 2c2 is positioned approximately parallel to the direction perpendicular to the tube axis of the tubular portion 10. This makes it possible to reduce the area occupied by the structure for fixing the ultrasonic sensor 30 to the electrode portion 2a of the two-electrode sensor 20 in the longitudinal direction of the tubular portion 10. This makes it possible to reduce the size of the monitoring probe 1 in the tube axis direction of the tubular portion 10.

[0101] Furthermore, the rod-shaped member 2c3 is positioned such that its longitudinal direction is substantially parallel to the axial direction of the tubular portion 10, restricting rotation of the fixing block 2c1. The ultrasonic sensor 30 is sandwiched between the other end of the electrode unit of the two-electrode sensor 20 (i.e., the end face of the exposed portion 2a2 of the electrode portion 2a in the electrode unit), the rod-shaped member 2c3, and the fixing block 2c1. This makes it possible for the rod-shaped member 2c3 to prevent the fixing block 2c1 from rotating in conjunction with rotation of the fixing bolt 2c2. This makes it possible to more reliably fix the ultrasonic sensor 30 to the electrode portion 2a of the two-electrode sensor 20.

[0102] Furthermore, the ultrasonic sensor 30 is sandwiched between the other end of the electrode unit of the two-electrode sensor 20 (i.e., the end face of the exposed portion 2a2 of the electrode portion 2a in the electrode unit), the elastic member 2c5 whose longitudinal direction is approximately parallel to the direction orthogonal to the tube axis, and the second fixing block 2c4. This makes it easier to maintain the ultrasonic sensor 30 in contact with the electrode portion 2a of the two-electrode sensor 20, for example, by pressing the ultrasonic sensor 30 against the end face of the exposed portion 2a2 of the electrode portion 2a of the electrode unit. This makes it easier to accurately measure the thickness of the electrode portion 2a of the two-electrode sensor 20 by the ultrasonic sensor 30.

[0103] Furthermore, because the elastic member 2c5 is positioned approximately parallel to the direction orthogonal to the tube axis, the force with which the elastic member 2c5 presses the ultrasonic sensor 30 against the electrode portion 2a of the two-electrode sensor 20 is less likely to weaken even under high-temperature conditions. Therefore, for example, even when the monitoring probe 1 is placed in a high-temperature environment, the force with which the ultrasonic sensor 30 is pressed against the electrode portion 2a of the two-electrode sensor 20 is less likely to weaken. Also, rotation of the ultrasonic sensor 30 can be suppressed compared to, for example, when the ultrasonic sensor 30 is brought into contact with the electrode portion 2a of the two-electrode sensor 20 by rotation of the fixing bolt 2c2. Furthermore, the area occupied by the elastic member 2c5 in the tube axis direction of the tubular portion 10 can be reduced, making it possible to more reliably reduce the size of the monitoring probe 1 in the tube axis direction of the tubular portion 10.

[0104] Furthermore, the ultrasonic sensor 30 is biased by a biasing member 2c6 toward the other end of the two-electrode sensor 20 (i.e., the end face of the exposed portion 2a2 of the electrode portion 2a in the electrode unit). This makes it easier, for example, for the ultrasonic sensor 30 to maintain contact with the electrode portion 2a of the two-electrode sensor 20. This makes it easier for the ultrasonic sensor 30 to accurately measure the thickness of the electrode portion 2a of the two-electrode sensor 20.

[0105] The two-electrode sensor 20 includes a first electrode unit 21, a second electrode unit 22, a third electrode unit 23, and a fourth electrode unit 24, and the ultrasonic sensor 30 includes a first ultrasonic sensor 31, a second ultrasonic sensor 32, a third ultrasonic sensor 33, and a fourth ultrasonic sensor 34. The first ultrasonic sensor 31 is disposed in a portion of the first electrode unit 21 that is on the other end side of the first electrode unit 21, and the second ultrasonic sensor 32 is disposed in a portion of the second electrode unit 22 that is on the other end side of the second electrode unit 22. The third ultrasonic sensor 33 is disposed in a portion of the third electrode unit 23 that is on the other end side of the third electrode unit 23, and the fourth ultrasonic sensor 34 is disposed in a portion of the fourth electrode unit 24 that is on the other end side of the fourth electrode unit 24. That is, each of these ultrasonic sensors 30 is disposed on an end surface of the exposed portion 2a2 of the electrode portion 2a included in each of the electrode units of the two-electrode sensor 20. As a result, the first ultrasonic sensor 31 can measure the thickness of the electrode portion 2a of the first electrode unit 21, and the second ultrasonic sensor 32 can measure the thickness of the electrode portion 2a of the second electrode unit 22. Furthermore, the third ultrasonic sensor 33 can measure the thickness of the electrode portion 2a of the third electrode unit 23, and the fourth ultrasonic sensor 34 can measure the thickness of the electrode portion 2a of the fourth electrode unit 24.

[0106] The thicknesses of the electrode portions 2a of the first electrode unit 21, second electrode unit 22, third electrode unit 23, and fourth electrode unit 24 are different from one another. As a result, for example, the measurement results of the thicknesses of these electrode portions 2a are different from one another, making it easier to intuitively determine the electrode unit corresponding to the thickness measurement results. Therefore, it is easier to prevent mistakes in measurement locations.

[0107] Furthermore, the first processing device 91 in the receiving device 90, which receives the measurement signal from the ultrasonic sensor 30, is installed at the base of the tubular portion 10. This makes it possible to reduce the distance between the ultrasonic sensor 30 and the first processing device 91 while suppressing the effects of the first processing device 91 being installed inside the tubular portion 10 (for example, damage due to high temperatures). Therefore, it is possible to provide a structure that is advantageous for miniaturizing the monitoring probe 1 while making it easier to reduce the effects of noise on the measurement signal received by the first processing device 91.

[0108] Furthermore, a cable 80 that transmits the measurement signal of the ultrasonic sensor 30 and the measurement signal of the two-electrode sensor 20 is disposed inside the tubular portion 10. This allows the measurement signal of the ultrasonic sensor 30 and the measurement signal of the two-electrode sensor 20 to be properly transmitted while the cable 80 is protected by the tubular portion 10.

[0109] The receiving device 90 also includes a first processing device 91 that processes the measurement signal of the ultrasonic sensor 30, and a second processing device 92 that processes the measurement signal of the two-electrode sensor 20. A switch A switches the signal transmitted by the cable 80 from one of the first processing device 91 and the second processing device 92 to the other. This allows the receiving device 90 to appropriately process the results of the thickness measurement of the electrode portion 2 a of the two-electrode sensor 20 by the ultrasonic sensor 30 and the results of the electrochemical measurement by the two-electrode sensor 20.

[0110] Furthermore, the negative electrode side of the switch A is insulated. This allows, for example, electrochemical measurement to be performed reliably using the two-electrode sensor 20. Furthermore, the influence of noise caused by the environment where the monitoring probe 1 is installed can be reduced when the ultrasonic sensor 30 measures the thickness of the electrode portion 2a of the two-electrode sensor 20.

[0111] The cable 80 is positioned on the opposite side of the ultrasonic sensor 30, sandwiching the tube axis of the tubular portion 10. This makes it easier to apply hot air to the electrode unit to adjust the temperature of the electrode unit of the two-electrode sensor 20 and recreate a corrosive environment, for example.

[0112] Here, for example, if the tubular portion 10 is a rectangular tube, when the tubular portion 10 is deformed due to thermal expansion or the like, the shape of the tubular portion 10 may become distorted. Therefore, the tubular portion 10 is cylindrical. This makes it easier to thermally expand the tubular portion 10 uniformly in the radial direction compared to when the tubular portion 10 is a square tube, for example. Therefore, for example, it is easier to prevent the sensor from being distorted due to deformation of the tubular portion 10.

[0113] Furthermore, the boiler B according to this embodiment is provided with the monitoring probe 1 according to the present disclosure. The thickness of the two-electrode sensor 20 in the monitoring probe 1 is greater than the thickness of the superheater tube BP included in the boiler B. This makes it easier to relatively reduce the influence of noise caused by the environment of the boiler B when measuring the thickness of an electrode unit (e.g., the first electrode unit 21) using the ultrasonic sensor 30.

[0114] Furthermore, the boiler B is provided with a monitoring probe 1 according to this embodiment. The monitoring probe 1 and the boiler B are connected via an insulating member I. This makes it possible to easily reduce the influence of noise caused by the environment of the boiler B on the thickness measurement of the electrode unit (e.g., the first electrode unit 21) by the ultrasonic sensor 30 and the electrochemical measurement by the two-electrode sensor 20.

[0115] The technical scope of the present disclosure is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present disclosure. The conductor 40 does not have to be substantially parallel to the direction perpendicular to the tube axis of the tubular portion 10 . The two-electrode sensor 20 may have more than four electrode units, or may have only two or three electrode units, and the electrode units of the two-electrode sensor 20 do not have to be positioned adjacent to each other.

[0116] The ultrasonic sensor 30 does not have to be located inside the insulating holder 60 when viewed in the direction perpendicular to the pipe axis. Two or more thermocouples 50 and insulating holders 60 may be provided for one ultrasonic sensor 30, or none may be provided. In addition, the monitoring probe 1 may not be provided with the thermocouple 50 and insulating holder 60.

[0117] The insulating holder 60 does not have to be located inside the metal holder 70 when viewed in the direction orthogonal to the tube axis. Also, the monitoring probe 1 does not have to be provided with the metal holder 70. The portion on one end side of the electrode unit does not need to protrude from the metal holder 70 . In a configuration in which the ultrasonic sensor 30 is fixed by the fixing block 2c1 and the fixing bolt 2c2, the ultrasonic sensor 30 does not have to be sandwiched between the part of the first electrode unit 21 on the other end side and the rod-shaped member 2c3 or the fixing block 2c1.

[0118] The monitoring probe 1 does not have to have a configuration for pressing the ultrasonic sensor 30 against the electrode portion 2a of the electrode unit by the fixing block 2c1, fixing bolt 2c2, elastic member 2c5, or biasing member 2c6. The ultrasonic sensor 30 may be adhered to the electrode portion 2a of the electrode unit with a conductive adhesive, for example. The thicknesses of the plurality of electrode portions 2a do not need to be different from one another. The receiving device 90 does not have to be located at the base of the tubular portion 10 . The cable 80 does not have to be disposed inside the tubular portion 10 . The cable 80 does not have to be located on the opposite side of the ultrasonic sensor 30 across the tube axis of the tubular portion 10 . The tubular portion 10 does not have to be cylindrical. The thickness of the two-electrode sensor 20 does not need to be greater than the thickness of the tubes BP of the superheater included in the boiler B. The monitoring probe 1 and the boiler B do not necessarily have to be connected via the insulating member I.

[0119] In addition, within the scope of the present disclosure, the components in the above-described embodiments may be replaced with well-known components as appropriate, and the above-described modified examples may be combined as appropriate.

[0120] (Addendum) The monitoring probe and the boiler according to the above embodiment can be understood, for example, as follows.

[0121] <1> A monitoring probe according to one aspect of the present disclosure comprises a tubular portion, a two-electrode sensor provided in the tubular portion and used for electrochemical measurements, and an ultrasonic sensor, wherein one end side of a first electrode included in the two-electrode sensor is located outside the tubular portion, and the other end side of the first electrode is located inside the tubular portion, the ultrasonic sensor is disposed in a portion of the first electrode on the other end side, and the ultrasonic sensor measures the thickness of the first electrode.

[0122] In the monitoring probe described above, one end of the first electrode included in the two-electrode sensor is located outside the tubular portion, and the other end of the first electrode is located inside the tubular portion. The ultrasonic sensor is disposed in a portion of the first electrode on the other end side. That is, the first electrode and the ultrasonic sensor are disposed so as to overlap in a direction perpendicular to the tubular axis of the tubular portion.

[0123] This allows the area occupied in the axial direction of the tubular portion to be smaller than when, for example, the first electrode and the ultrasonic sensor are positioned so as not to overlap in the direction perpendicular to the axial direction of the tubular portion (so as to be aligned in the axial direction of the tubular portion). Therefore, by making it easier to shorten the length of the tubular portion in the axial direction, it is possible to contribute to miniaturization of the monitoring probe in the axial direction of the tubular portion.

[0124] Furthermore, by arranging the first electrode and the ultrasonic sensor so that they overlap in the direction perpendicular to the axial direction of the tubular portion, the first electrode of the two-electrode sensor can be used as the target for measuring the wall thickness using the ultrasonic sensor. This reduces the need to secure an area for measuring the wall thickness of the tubular portion using the ultrasonic sensor, allowing the tubular portion to be shortened. This also contributes to the miniaturization of the monitoring probe in the axial direction of the tubular portion.

[0125] The two-electrode sensor is used for electrochemical measurement, and the ultrasonic sensor measures the thickness of the first electrode included in the two-electrode sensor. This allows the electrochemical measurement by the two-electrode sensor and the measurement of the thickness of the first electrode by the ultrasonic sensor to be performed at the same location on the tubular portion.

[0126] Depending on the environment where the monitoring probe is installed (for example, inside a boiler or furnace), an oxide film may form on the outer surface of the tubular part. If the thickness of the tubular part is measured using an ultrasonic sensor, the ultrasonic waves emitted by the ultrasonic sensor during measurement are reflected by the oxide film. Therefore, if the measured thickness value changes, it becomes unclear whether the change in the measurement value is due to an actual change in the thickness of the tubular part or the influence of the oxide film.

[0127] By performing electrochemical measurements using the two-electrode sensor and measuring the thickness of the first electrode using the ultrasonic sensor at the same location on the tubular portion, it is possible to determine whether an oxide film has formed on the first electrode from the impedance of the first electrode during electrochemical measurements using the two-electrode sensor, while measuring the thickness of the first electrode using the ultrasonic sensor. This not only enables accurate measurement of changes in the thickness of the first electrode, but also makes it easier to understand the corrosion status at the location where the monitoring probe is installed.

[0128] <2> the above <1> The monitoring probe according to the above may further include a conductor for transmitting a measurement signal from the ultrasonic sensor, and the longitudinal direction of the conductor may be substantially parallel to a direction perpendicular to the tube axis of the tubular portion.

[0129] In the above-described monitoring probe, the longitudinal direction of the conductor for transmitting the measurement signal from the ultrasonic sensor is substantially parallel to the direction perpendicular to the axial direction of the tubular portion. This makes it easier to reduce the size of the area in which the conductor is located in the axial direction of the tubular portion. This makes it possible to more reliably reduce the size of the monitoring probe in the axial direction of the tubular portion.

[0130] <3> the above <1> or <2> In the monitoring probe according to the above, the two-electrode sensor may include the first electrode and the second electrode, and the first electrode and the second electrode may be arranged so as to be close to each other.

[0131] According to the above monitoring probe, the two-electrode sensor includes a first electrode and a second electrode. For example, if a two-electrode sensor has two electrodes connected together in a non-switchable circuit, electrochemical measurement can be performed only in the area between the two electrodes. In contrast, if a two-electrode sensor functions using two combinations of multiple individually provided electrodes (e.g., a first electrode and a second electrode), the area between the two electrodes can be enlarged. Therefore, the detection area for electrochemical measurement can be further expanded. Furthermore, the first electrode and the second electrode are arranged close to each other, which allows the monitoring probe to be made smaller in size in the axial direction of the tubular portion.

[0132] <4> the above <1> from <3> The monitoring probe according to any one of the above aspects may further include a thermocouple and an insulating holder, wherein the two-electrode sensor includes the first electrode and the second electrode, and the first electrode and the thermocouple are located inside the insulating holder when viewed along a direction perpendicular to the tube axis of the tubular portion.

[0133] The above monitoring probe further includes a thermocouple and an insulating holder. By including a thermocouple in the monitoring probe, for example, the measurement result of the thickness of the first electrode by the ultrasonic sensor can be corrected for sound speed. Also, the influence of thermal expansion of the tubular portion and the two-electrode sensor can be corrected. Therefore, the accuracy of the measurement of the thickness of the first electrode by the ultrasonic sensor can be improved. Furthermore, by providing an insulating holder, for example, the first electrode can be insulated from the second electrode and the tubular portion. This makes it easier to reliably measure the current using the first electrode, thereby improving the accuracy of electrochemical measurements using the two-electrode sensor. This makes it easier to understand the corrosion status of the location where the monitoring probe is installed using electrochemical measurements using the two-electrode sensor.

[0134] Furthermore, the first electrode and the thermocouple are located inside the insulating holder when viewed in the direction perpendicular to the axial direction of the tubular portion. This reduces the area occupied by the first electrode, the thermocouple, and the insulating holder in the axial direction of the tubular portion. This makes it possible to more reliably reduce the size of the monitoring probe in the axial direction of the tubular portion.

[0135] <5> the above <4> In the monitoring probe according to the above, a configuration may be adopted in which the ultrasonic sensor is located inside the insulating holder when viewed along the direction orthogonal to the tube axis.

[0136] According to the above-described monitoring probe, the ultrasonic sensor is located inside the insulating holder when viewed in the direction perpendicular to the tube axis of the tubular portion. This positions the ultrasonic sensor so that it overlaps with the first electrode when viewed in the direction perpendicular to the tube axis of the tubular portion. This improves the accuracy of measuring the thickness of the first electrode using the ultrasonic sensor. Furthermore, the area occupied by the first electrode, thermocouple, insulating holder, and ultrasonic sensor in the axial direction of the tubular portion can be reduced. This more reliably enables the monitoring probe to be miniaturized in the axial direction of the tubular portion.

[0137] <6> the above <4> or <5> In the monitoring probe according to the above, a configuration may be employed in which one thermocouple and one insulating holder are provided for one ultrasonic sensor.

[0138] According to the above-described monitoring probe, one thermocouple and one insulating holder are provided for each ultrasonic sensor. This allows, for example, when multiple ultrasonic sensors are provided, the measurement results of the thickness of an electrode (e.g., the first electrode) measured by one ultrasonic sensor to be individually corrected for sound speed. In addition, the effects of thermal expansion of the tubular portion and the two-electrode sensor can be corrected more precisely. This allows for improved accuracy in measuring the thickness of an electrode (e.g., the first electrode) using an ultrasonic sensor.

[0139] <7> the above <4> from <6> In any one of the above aspects, the monitoring probe may further include a metal holder located between the tubular portion and the insulating holder, wherein the insulating holder is located inside the metal holder when viewed along a direction perpendicular to the tube axis, and the one end portion protrudes from the metal holder.

[0140] According to the above-described monitoring probe, the metal holder is positioned between the tubular portion and the insulating holder. The insulating holder is positioned inside the metal holder when viewed in a direction perpendicular to the axial direction of the tubular portion. This makes it easier to position the insulating holder relative to the tubular portion.

[0141] Furthermore, one end of the first electrode protrudes from the metal holder. This can prevent, for example, high-temperature molten salt from ash from adhering between the metal holder and the one end of the first electrode, causing electrical conduction between the metal holder and the first electrode and making electrochemical measurement impossible. This can facilitate reliable measurement of current by the first electrode. Therefore, it is easier to grasp the corrosion status of the location where the monitoring probe is installed through electrochemical measurement by the two-electrode sensor.

[0142] <8> the above <1> from <7> The monitoring probe according to any one of the above aspects may further include a fixing block that sandwiches the ultrasonic sensor between the part of the first electrode that is on the other end side and the fixing bolt that presses the fixing block against the ultrasonic sensor and is positioned with an axial direction approximately parallel to the direction perpendicular to the tube axis of the tubular section, and a rod-shaped member that is positioned with a longitudinal direction approximately parallel to the tube axis direction of the tubular section and that restricts rotation of the fixing block, and may adopt a configuration in which the ultrasonic sensor is sandwiched between the part of the first electrode that is on the other end side and the rod-shaped member.

[0143] According to the monitoring probe, the ultrasonic sensor is sandwiched between the fixing block and the other end of the first electrode. The fixing bolt presses the fixing block against the ultrasonic sensor. This allows the ultrasonic sensor to be fixed by pressing it against the first electrode.

[0144] The fixing bolt has an axial direction substantially parallel to the direction perpendicular to the axial direction of the tubular portion. This allows the structure for fixing the ultrasonic sensor to the first electrode to occupy a smaller area in the longitudinal direction of the tubular portion. This makes it possible to reduce the size of the monitoring probe in the axial direction of the tubular portion.

[0145] The rod-shaped member, whose longitudinal direction is substantially parallel to the axial direction of the tubular portion, restricts rotation of the fixing block. The ultrasonic sensor is sandwiched between the rod-shaped member and the other end of the first electrode. This allows the rod-shaped member to prevent the fixing block from rotating in accordance with rotation of the fixing bolt. This makes it possible to more reliably fix the ultrasonic sensor to the first electrode.

[0146] <9> the above <1> from <8> The monitoring probe according to any one of the above aspects may further include an elastic member whose longitudinal direction is approximately parallel to a direction perpendicular to the tube axis of the tubular portion, and the ultrasonic sensor may be sandwiched between the other end portion and the elastic member.

[0147] According to the monitoring probe, the ultrasonic sensor is sandwiched between the other end of the first electrode and an elastic member whose longitudinal direction is substantially parallel to the direction perpendicular to the tube axis. This makes it easier to maintain the ultrasonic sensor in contact with the first electrode, for example, by pressing the ultrasonic sensor against the first electrode. This makes it easier to accurately measure the thickness of the first electrode using the ultrasonic sensor.

[0148] Furthermore, by positioning the elastic member substantially parallel to the direction orthogonal to the tube axis, the force with which the elastic member presses the ultrasonic sensor against the first electrode can be made less likely to weaken even under high-temperature conditions. Therefore, for example, even when the monitoring probe is placed in a high-temperature environment, the force with which the ultrasonic sensor is pressed against the first electrode can be made less likely to weaken. Furthermore, rotation of the ultrasonic sensor can be suppressed compared to when the ultrasonic sensor is brought into contact with the first electrode by rotating a fixing bolt, for example. Furthermore, the area occupied by the elastic member in the axial direction of the tubular portion can be reduced, making it possible to more reliably miniaturize the monitoring probe in the axial direction of the tubular portion.

[0149] <10> the above <1> from <9> The monitoring probe according to any one of the above aspects may further include a biasing member, and the ultrasonic sensor may be biased by the biasing member toward the other end portion.

[0150] According to the monitoring probe, the ultrasonic sensor is biased by the biasing member toward the other end of the first electrode. This makes it easier to maintain contact between the ultrasonic sensor and the first electrode, for example. This makes it easier to accurately measure the thickness of the first electrode using the ultrasonic sensor.

[0151] <11> the above <1> from <10> In the monitoring probe according to any one of the above aspects, the two-electrode sensor may include the first electrode and the second electrode, one end of the second electrode being located outside the tubular portion and the other end of the second electrode being located inside the tubular portion, the ultrasonic sensor may include a first ultrasonic sensor and a second ultrasonic sensor, the first ultrasonic sensor being arranged on a part of the first electrode that is on the other end side of the first electrode, and the second ultrasonic sensor being arranged on a part of the second electrode that is on the other end side of the second electrode, and a thickness of the first electrode and a thickness of the second electrode may be different.

[0152] According to the above-mentioned monitoring probe, the two-electrode sensor includes a first electrode and a second electrode, and the ultrasonic sensor includes a first ultrasonic sensor and a second ultrasonic sensor. The first ultrasonic sensor is disposed on a portion of the first electrode that is closer to the other end of the first electrode, and the second ultrasonic sensor is disposed on a portion of the second electrode that is closer to the other end of the second electrode. This allows the thickness of the first electrode to be measured by the first ultrasonic sensor, and the thickness of the second electrode to be measured by the second ultrasonic sensor.

[0153] The thickness of the first electrode and the thickness of the second electrode are different. This makes it easier to intuitively determine which electrode corresponds to the thickness measurement results, for example, because the thickness measurement results of these electrodes are different from each other. This makes it easier to prevent mistakes in measurement locations.

[0154] <12> the above <1> from <11> In any one of the above aspects, the monitoring probe may further include a receiving device that receives a measurement signal from the ultrasonic sensor, and the receiving device may be installed at the base of the tubular portion.

[0155] According to the above-described monitoring probe, the receiving device that receives the measurement signal from the ultrasonic sensor is installed at the base of the tubular portion. This reduces the influence of the receiving device that receives the measurement signal from the ultrasonic sensor due to being installed inside the tubular portion (for example, damage due to high temperatures), while reducing the distance between the ultrasonic sensor and the receiving device that receives the measurement signal from the ultrasonic sensor. This makes it easier to reduce the influence of noise on the measurement signal received by the receiving device that receives the measurement signal from the ultrasonic sensor, while providing a structure that is advantageous for miniaturizing the monitoring probe.

[0156] <13> the above <12> The monitoring probe according to the above may further include a cable that transmits the measurement signals of the ultrasonic sensor and the two-electrode sensor, and a switch that is installed at the base of the tubular portion, wherein the cable is disposed inside the tubular portion, the receiving device includes a first processing device that processes the measurement signals of the ultrasonic sensor and a second processing device that processes the measurement signals of the two-electrode sensor, and the switch may be configured to switch the signals transmitted by the cable from one of the first processing device and the second processing device to the other.

[0157] According to the above-described monitoring probe, the cables for transmitting the measurement signals of the ultrasonic sensor and the two-electrode sensor are disposed inside the tubular portion, thereby enabling the measurement signals of the ultrasonic sensor and the two-electrode sensor to be properly transmitted while the cables are protected by the tubular portion.

[0158] The receiving device also includes a first processing device that processes the measurement signal of the ultrasonic sensor and a second processing device that processes the measurement signal of the two-electrode sensor. The switch switches the signal transmitted by the cable from one of the first processing device and the second processing device to the other. This allows the receiving device to appropriately process the results of the electrode (e.g., first electrode) thickness measurement by the ultrasonic sensor and the results of the electrochemical measurement by the two-electrode sensor.

[0159] <14> the above <13> In the monitoring probe according to the above, a configuration may be adopted in which the negative electrode side of the switch is insulated.

[0160] According to the above-described monitoring probe, the negative electrode side of the switch is insulated. This allows, for example, electrochemical measurement using a two-electrode sensor to be performed reliably. Furthermore, the influence of noise caused by the environment where the monitoring probe is installed can be reduced when measuring the thickness of an electrode (e.g., the first electrode) using an ultrasonic sensor.

[0161] <15> the above <13> or <14> In the monitoring probe according to the above, a configuration may be adopted in which the cable is positioned on the opposite side of the ultrasonic sensor, sandwiching the tubular axis of the tubular portion therebetween.

[0162] In the above-described monitoring probe, the cable is positioned on the opposite side of the ultrasonic sensor across the tubular axis of the tubular portion, which makes it easier to apply hot air to the electrode (e.g., the first electrode) to adjust the temperature of the electrode and recreate a corrosive environment.

[0163] <16> the above <1> from <15> In the monitoring probe according to any one of the above aspects, a configuration may be employed in which the tubular portion is cylindrical.

[0164] Here, for example, if the tubular portion is a rectangular tube, the shape of the tubular portion may become distorted when the tubular portion is deformed due to thermal expansion or the like. Therefore, in the monitoring probe described above, the tubular portion is cylindrical. This makes it easier to thermally expand the tubular portion uniformly in the radial direction compared to when the tubular portion is rectangular. Therefore, for example, it is easier to prevent the sensor from being distorted due to deformation of the tubular portion.

[0165] <17> The boiler according to one aspect of the present disclosure includes the above-mentioned <1> from <16> A boiler provided with a monitoring probe according to any one of the above aspects, characterized in that the thickness of the two-electrode sensor is thicker than the thickness of a tube of a superheater included in the boiler.

[0166] The boiler is provided with a monitoring probe according to the present disclosure. The thickness of the two-electrode sensor in the monitoring probe is greater than the thickness of the superheater tubes included in the boiler. This makes it easier to relatively reduce the influence of noise caused by the boiler environment when measuring the thickness of an electrode (e.g., the first electrode) using an ultrasonic sensor.

[0167] <18> The boiler according to one aspect of the present disclosure includes the above-mentioned <1> from <16> A boiler provided with the monitoring probe according to any one of the above aspects, characterized in that the monitoring probe and the boiler are connected via an insulating member.

[0168] The boiler is provided with a monitoring probe according to the present disclosure. The monitoring probe and the boiler are connected via an insulating member. This makes it possible to easily reduce the influence of noise caused by the boiler environment on the thickness measurement of an electrode (e.g., the first electrode) using an ultrasonic sensor and on electrochemical measurement using a two-electrode sensor. [Explanation of symbols]

[0169] 1 Monitoring Probe 10 Tubular part 20 Two-electrode sensor 21 First electrode unit 22 Second electrode unit 23 Third electrode unit 24 4th electrode unit 30 Ultrasonic Sensor 31 First ultrasonic sensor 32 Second ultrasonic sensor 33 Third ultrasonic sensor 34 4th ultrasonic sensor 40 Conductors 41 Conductor 50 thermocouples 60 Insulation holder 70 Metal holder 80 Cable 90 Receiving device 91 First processing device 92 Second processing device A switch B Boiler I. Insulating material

Claims

1. a tubular portion; a two-electrode sensor provided in the tubular portion and used for electrochemical measurements; an ultrasonic sensor; A monitoring probe comprising: one end side of a first electrode included in the two-electrode sensor is located outside the tubular portion, the other end side of the first electrode is located inside the tubular portion, the ultrasonic sensor is disposed in a portion of the first electrode on the other end side, The ultrasonic sensor measures the thickness of the first electrode. A monitoring probe characterized by:

2. a conductor for transmitting a measurement signal of the ultrasonic sensor; Further provided with The longitudinal direction of the conductor is approximately parallel to the direction perpendicular to the tube axis of the tubular portion. The monitoring probe according to claim 1 .

3. the two-electrode sensor includes the first electrode and a second electrode; The first electrode and the second electrode are disposed adjacent to each other. The monitoring probe according to claim 1 .

4. A thermocouple, an insulating holder; Further provided with the two-electrode sensor includes the first electrode and a second electrode; the first electrode and the thermocouple are located inside the insulating holder when viewed along a direction perpendicular to the tube axis of the tubular portion. The monitoring probe according to claim 1 .

5. The ultrasonic sensor is located inside the insulating holder when viewed along the direction orthogonal to the tube axis.

5. The monitoring probe according to claim 4.

6. The thermocouple and the insulating holder are provided one by one for each ultrasonic sensor. The monitoring probe according to claim 5 .

7. a metal holder positioned between the tubular portion and the insulating holder; Further provided with the insulating holder is located inside the metal holder when viewed along the direction orthogonal to the tube axis, The one end portion protrudes from the metal holder.

5. The monitoring probe according to claim 4.

8. a fixing block that sandwiches the ultrasonic sensor between the first electrode and a portion of the first electrode on the other end side; a fixing bolt whose axial direction is positioned approximately parallel to a direction perpendicular to the pipe axis of the tubular portion and which presses the fixing block against the ultrasonic sensor; a rod-shaped member whose longitudinal direction is positioned approximately parallel to the axial direction of the tubular portion and which restricts rotation of the fixed block; Further provided with The ultrasonic sensor is sandwiched between a portion of the first electrode on the other end side and the rod-shaped member.

7. The monitoring probe according to claim 1, wherein the first electrode is a conductive material.

9. an elastic member whose longitudinal direction is substantially parallel to a direction perpendicular to the axial direction of the tubular portion; Further provided with The ultrasonic sensor is sandwiched between the other end portion and the elastic member.

7. The monitoring probe according to claim 1, wherein the first electrode is a conductive material.

10. a biasing member; Further provided with The ultrasonic sensor is biased by the biasing member toward the other end portion.

7. The monitoring probe according to claim 1, wherein the first electrode is a conductive material.

11. the two-electrode sensor includes the first electrode and a second electrode; one end side of the second electrode is located outside the tubular portion, the other end side of the second electrode is located inside the tubular portion, the ultrasonic sensor includes a first ultrasonic sensor and a second ultrasonic sensor; the first ultrasonic sensor is disposed in a portion of the first electrode on the other end side of the first electrode, the second ultrasonic sensor is disposed in a portion of the second electrode on the other end side of the second electrode, The thickness of the first electrode and the thickness of the second electrode are different.

7. The monitoring probe according to claim 1, wherein the first electrode is a conductive material.

12. a receiving device for receiving a measurement signal from the ultrasonic sensor; Further provided with The receiving device is located at the base of the tubular portion.

7. The monitoring probe according to claim 1, wherein the first electrode is a conductive material.

13. a cable for transmitting a measurement signal from the ultrasonic sensor and a measurement signal from the two-electrode sensor; a switch disposed at a base of the tubular portion; Further provided with the cable is disposed inside the tubular portion; the receiving device includes a first processing device that processes a measurement signal of the ultrasonic sensor and a second processing device that processes a measurement signal of the two-electrode sensor; the switch switches the signal transmitted by the cable from one of the first processing device and the second processing device to the other; 13. The monitoring probe of claim 12.

14. The negative side of the switch is insulated.

14. The monitoring probe of claim 13.

15. The cable is positioned on the opposite side of the ultrasonic sensor across the tubular portion's axis.

14. The monitoring probe of claim 13.

16. The tubular portion is cylindrical.

7. The monitoring probe according to claim 1, wherein the first electrode is a conductive material.

17. A boiler provided with a monitoring probe according to any one of claims 1 to 6, The thickness of the two-electrode sensor is greater than the thickness of a tube of a superheater included in the boiler. A boiler characterized by:

18. A boiler including a monitoring probe according to any one of claims 1 to 6, The monitoring probe and the boiler are connected via an insulating member. A boiler characterized by:

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