JP2009174889A - Structure for installing thermocouple in tube wall and method for installing thermocouple - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a structure and a method for installing a thermocouple in a tube wall which enable avoidance of puncture of a sheath due to an output of welding or others and can make installation work efficient, while enabling embedment of the thermocouple in a groove without forming a gap, and which enable avoidance of irregularity of temperature distribution and improvement of the accuracy in temperature measurement. <P>SOLUTION: The width of a recess groove 10 is set to be a prescribed one larger than a sheath diameter of a sheathed thermocouple 1 to be installed internally and a holding plate 2 to be fitted in the recess groove 10 is provided. A first storing groove 20 having a curved surface R1 for compactly storing a half 1a of the cross-sectional outer side of the sheathed thermocouple 1 is formed almost in the central part of the inside of the holding plate 2, while a second storing groove 30 having a curved surface R2 for compactly storing about a half 1b of the cross-sectional inner side of the sheathed thermocouple 1 being the remaining portion thereof is formed almost in the central part of the bottom side 10c of the recess groove 10. The sheathed thermocouple 1 is embedded in the recess groove 10 in a state that it is held compactly between the first storing groove 20 and the second storing groove 30 in this structure. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a thermocouple mounting structure for measuring the temperature of a heated tube wall such as a water tube of a boiler, and more specifically, forming a groove along the outer peripheral surface of the tube wall. The present invention relates to a thermocouple mounting structure and a mounting method in which a sheath thermocouple is embedded.

  As this type of thermocouple mounting structure, conventionally, for example, a groove having a depth within the allowable limit of the tube thickness and a width approximately twice that of the tube thickness is drilled along the circumferential surface of the tube wall. A thermocouple with a slightly smaller cross-sectional area is fitted in the groove, and the thermocouple is pressed and deformed from above to be in close contact with the groove bottom, and is fixed to the outer peripheral surface of the tube wall by welding or the like. Has been proposed (see, for example, Patent Document 1). It has good adhesion to the embedded groove bottom and can be used to measure the temperature close to the true temperature of the tube without extra protrusion on the outer surface of the tube wall. A structure without such mechanical strength deterioration can be provided.

  However, in the structure of Patent Document 1, since the thermocouple is fitted into the groove and press-molded, the tube wall and the thermocouple are directly welded and fixed, so that the sheath is punctured (thermal destruction). There was a fear. Therefore, in practice, as shown in FIGS. 14A and 14B, a pressing plate 102 that further presses the thermocouple 101 fitted in the groove 110 from the outside is provided, and the pressing plate 102 is attached to the tube wall W. A welded structure was used. However, in such a structure that is fixed via the pressing plate 102, the thermal damage can be prevented to some extent as compared with the structure in which the sheath is directly welded, but the depth of the groove that can be formed in the tube wall W is defined within a predetermined dimension. Therefore, the thickness of the holding plate 102 is limited, and if the welding output is too large, the arc easily jumps and punctures the sheath of the thermocouple 101. Since the gaps s1 and s1 are generated between the flat pressing plate 102 and the pressure-deformed thermocouple 101 having a curved surface, there is a problem in that temperature measurement is disturbed and temperature measurement accuracy is lowered.

  As another structure, an annular groove in the circumferential direction perpendicular to the axial direction of the pipe is formed on the outer peripheral surface of the pipe, and the inner peripheral surface of the half-arc-shaped embedded plate that can be fitted into the annular groove of the pipe. A sheath having a tip temperature sensing portion formed in a flat cross section is stored in the engraved storage groove, and this embedded plate and the other half-divided arc-shaped embedded plate having no storage groove on the inner peripheral surface are connected to the outer peripheral surface of both embedded plates. It has been proposed that the tube is fitted in the annular groove of the tube so that the outer peripheral surface of the tube is the same surface, and is fixed to the joint outer peripheral surface of the embedding plate and the tube by welding (for example, see Patent Document 2). ). Such an embedded plate can be made thicker than the above-described holding plate 102 by the amount of the storage groove, and avoids the problem of an arc flying to the thermocouple sheath during welding with the tube wall. There is an advantage that the mounting work can be easily performed. However, since the thermocouple is housed in the storage groove on the inner circumferential surface of the embedded groove and is fitted into the annular groove, a gap is generated between the thermocouple on the side facing the bottom surface of the annular groove and the storage groove. It has the same problem as the above-mentioned structure that the temperature measurement accuracy is reduced.

Japanese Patent Publication No. 56-4849 Japanese Utility Model Publication No.59-20656

  Therefore, in view of the above-mentioned situation, the present invention intends to solve the problem that the sheath puncture due to the output of welding or the like can be avoided in the thermocouple mounting structure in which the sheath thermocouple is embedded in the groove formed in the tube wall. To the tube wall that can improve the efficiency of installation work, and can embed a thermocouple without creating a gap in the groove, avoiding disturbance of temperature distribution and improving temperature measurement accuracy The thermocouple mounting structure and mounting method are provided.

  In order to solve the above-described problems, the present invention provides a thermocouple mounting structure in which a concave groove is formed along the outer peripheral surface of a tube wall, and a sheath thermocouple is embedded in the concave groove, and the concave groove is internally provided. A presser plate that is set to a predetermined width wider than the sheath diameter of the sheathed thermocouple, and is provided with a presser plate that is fitted into the concave groove, and the outer side in a cross-sectional view of the sheathed thermocouple is substantially at the substantially central portion on the inner surface side of the presser plate. A first storage groove having a curved surface for storing the half without a gap is formed, and a sheath is formed at a substantially central portion of the bottom surface of the concave groove or the outer surface of the support plate fitted to the bottom side of the concave groove. Provided is a thermocouple mounting structure on a tube wall, characterized in that a second storage groove having a curved surface for storing the inner half of the remaining portion of the thermocouple, which is substantially the inner side in cross section, is stored without a gap. .

  Here, a structure in which the outer surface of the pressing plate is set so as to be substantially flush with the outer peripheral surface of the tube wall in a state of being fitted into the concave groove is preferable.

  In addition, it is preferable that a sheath thermocouple is sandwiched between the pressing plate and the support plate, and then the clamping body is fitted into the concave groove, and in particular, the pressing plate and the support plate constituting the clamping body. Are preferably integrated with each other by laser welding.

  In addition, the concave groove is formed over the entire circumference of the outer peripheral surface of the tube wall, and the sheath thermocouple has a structure in which each of the plus and minus strands extends from the hot junction at the distal end to the same side toward the proximal end. A dummy tube containing a thermocouple wire and an inorganic insulator is connected to the distal end side of the sheath thermocouple, and a connected body composed of the sheath thermocouple and the dummy tube is connected to the first housing. A structure in which the entire circumference is mounted by the groove and the second storage groove is preferable.

  Alternatively, the concave groove is formed over the entire circumference of the outer peripheral surface of the tube wall, and the sheath thermocouple is connected so that each of the strands on the plus side and the minus side from the hot junction located in the middle of the sheath axial direction faces both ends of the sheath. A structure in which the sheath thermocouples are extended to opposite sides and the sheath thermocouple is attached to the entire circumference by the first storage groove and the second storage groove is also a preferred embodiment.

  Furthermore, it is preferable that the sheath thermocouple has a double tube structure in which a soft metal layer is provided on the outer periphery side of the sheath.

  According to the present invention, in the above-described thermocouple mounting structure of the present invention in which the sheath thermocouple is mounted in a flat state in cross section, the sheath thermocouple is molded in advance in a flat state in cross section, and then the first There is also provided a method of attaching a thermocouple to be mounted in the same flat inner space formed by the storage groove and the second storage groove.

  In the thermocouple mounting structure according to the present invention as described above, the first storage groove having a curved surface for storing the outer half in a sectional view of the sheath thermocouple without a gap at the substantially central portion on the inner surface side of the holding plate. Therefore, the thickness can be set larger than that of the conventional pressing plate shown in FIG. 14, and therefore, it is possible to prevent the arc from jumping and puncturing the thermocouple sheath during welding work, thereby improving work efficiency. In addition to being able to achieve this, the penetration can be deepened, and the integration of the holding plate and the tube wall is improved. In the present invention, the outer half of the thermocouple in a sectional view is accommodated in a first housing groove having a curved surface formed on a holding plate, and the remaining inner half is disposed on the bottom surface of the groove or on the bottom side of the groove. It has been proposed in the past because it is housed in a second housing groove having a curved surface formed on a support plate fitted to the base plate, and the thermocouple is sandwiched between the first housing groove and the second housing groove without any gap. As a result, there are no gaps as seen in the various structures, and therefore, the temperature distribution is not disturbed and the temperature measurement accuracy can be improved.

  Further, when the support plate is fitted to the bottom side of the concave groove, a sandwich thermocouple is sandwiched between the pressing plate and the support plate, and then the sandwiched body is fitted into the concave groove. As a result, installation is easy and work efficiency can be improved. In this case, if the pressing plate and the support plate constituting the sandwiching body are integrated with each other by laser welding, the adhesion to the thermocouple can be reliably maintained.

  In addition, the concave groove is formed over the entire circumference of the outer peripheral surface of the tube wall, and the sheath thermocouple has a structure in which each of the plus and minus strands extends from the hot junction at the distal end to the same side toward the proximal end. A dummy tube containing a thermocouple wire and an inorganic insulator is connected to the distal end side of the sheath thermocouple, and a connected body composed of the sheath thermocouple and the dummy tube is connected to the first housing. Since the entire circumference is mounted by the groove and the second storage groove, it is possible to avoid the occurrence of a gap on the distal end side compared to a structure in which the concave groove on the distal end side of the sheath thermocouple is closed by other members, and the dummy. Since the tube has the same configuration as the sheathed thermocouple, the thermal conductivity is substantially the same, and the temperature measurement accuracy can be improved without causing a disturbance in the temperature distribution.

  In addition, the concave groove is formed over the entire circumference of the outer peripheral surface of the tube wall, and the sheath thermocouple is connected so that each of the strands on the plus side and the minus side from the warm junction located in the middle of the sheath axial direction faces both ends of the sheath. Since the sheath thermocouple is mounted over the entire circumference by the first storage groove and the second storage groove, all the concave grooves are closed by the sheath thermocouple, and another member or Without providing a dummy tube, the temperature distribution is stable, and the number of strands per pair passing through the sheath cross-section is halved, so that the cross-sectional area can be reduced, and the width of the groove and presser plate is also reduced. Because it is small, the temperature distribution is less disturbed and the measurement accuracy is remarkably improved, and the number of strands per cross section is halved, so it is necessary to check the position of the strands when mounting or deforming But Eliminated (in particular unnecessary strands alignment For one position.), It contributes to cost reduction and work efficiency.

  In addition, since the sheath thermocouple has a double tube structure in which a soft metal layer is provided on the outer periphery side of the sheath, the soft metal layer is formed even if there is a minute gap in each inner wall of the storage groove with which the sheath thermocouple contacts. Since it deforms softly and fills a minute gap to improve adhesion, thereby reducing the contact thermal resistance, the temperature measurement accuracy can be further improved.

  In the case where the sheath thermocouple is mounted in a flat state in cross section, after the sheath thermocouple is pre-formed in a flat state in cross section, the first storage groove and the second storage groove Since it is mounted in the same flat inner space to be formed, assembly is facilitated and good adhesion can be reliably maintained.

  Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a diagram showing an overall configuration employing a thermocouple mounting structure according to the present invention, FIGS. 1 to 10 show the first embodiment and its modifications, FIGS. 11 to 13 show the second embodiment, In the figure, reference numeral S denotes a thermocouple mounting structure, W denotes a tube wall, 1 denotes a sheath thermocouple, 2 denotes a pressing plate, 10 denotes a concave groove, 20 denotes a first storage groove, and 30 denotes a second storage groove. Yes.

  As shown in FIGS. 1 and 2, the thermocouple mounting structure S to the tube wall according to the present invention forms a concave groove 10 along the outer peripheral surface of the tube wall W, and a sheath thermocouple in the concave groove 10. 1 is embedded. Specifically, the pressing plate 2 is set to a predetermined width wider than the sheath diameter of the sheath thermocouple 1 in which the concave groove 10 is housed, and is fitted into the concave groove 10. As shown in FIG. 2, a first central portion provided with a curved surface R <b> 1 for accommodating the outer half 1 a in a sectional view of the sheath thermocouple 1 without a gap is provided at a substantially central portion on the inner surface side of the pressing plate 2. A storage groove 20 is formed, and a substantially central portion of the bottom surface 10c of the concave groove 10 is provided with a curved surface R2 for storing the remaining half of the sheath thermocouple 1 which is the inner half 1b in a sectional view without gaps. A second storage groove 30 is formed, and the sheath thermocouple 1 is connected to the first storage groove 20 and the second storage groove 30. Those embedded in the groove 10 in the gap without sandwiched state.

  The concave groove 10 formed in the tube wall W is engraved over the entire circumference in the circumferential direction perpendicular to the axial direction, and includes the second storage groove 30 formed at a substantially central portion of the bottom surface 10c. Is determined by regulations. In this example, the concave groove 10 is formed in the direction perpendicular to the axial direction as described above. However, the groove 10 may be formed obliquely with respect to the axial direction, or may be halfway without being provided on the entire circumference. It is. The width of the concave groove 10 is set to be a predetermined width larger than that of the thermocouple deformed into a flat cross section, and the pressing plate 2 having the same width is fitted thereto. The shape of the second storage groove 30 formed on the bottom surface 10c is set in accordance with the shape of the thermocouple to be deformed. In this example, the curved surface R2 is formed at both corners in the width direction, and the thermocouple is deformed flat. It is comprised in the shape which the outer peripheral surface of can closely_contact | adhere.

  The presser plate 2 is set to have a thickness substantially the same as the depth of the concave groove 10 excluding the first storage groove 20, a width is set to be substantially the same as the concave groove 10, and the presser plate 2 is recessed to the concave groove 10. 10, the outer surface of the pressing plate 2 is set so as to be substantially flush with the outer peripheral surface of the tube wall W. The shape of the first storage groove 20 formed in the substantially central portion on the inner surface side is set in accordance with the shape of the thermocouple to be deformed, as in the case of the second storage groove 30 described above. Curved surfaces R1 are formed at the corners at both ends in the direction, and the outer peripheral surface of the thermocouple deformed into a flat shape is configured to be in close contact. The material of the pressing plate 2 is preferably the same material as the tube wall W in order to avoid disturbance of the temperature distribution due to the difference in thermal conductivity, but other materials can also be adopted.

  Conventionally known sheath thermocouples 1 can be widely used. As shown in the longitudinal sectional view of FIG. 3A, the sheath thermocouple 1 is provided with a hot contact 12a inside the metal sheath 11 on the tip side and the like. It is configured to accommodate at least a pair of thermocouple wires 12, 12 extending in the same direction toward the end side, and an inorganic insulator 13 that fills the gap between the thermocouple wires 12 and the metal sheath 11. As the metal sheath 11, austenitic stainless steel (SUS304, SUS316, etc.), nickel chrome heat resistant alloy (Inconel) or the like can be used, and magnesium oxide (MgO) or the like is used as the inorganic insulator 13 filled in the sheath. Can be used. The thermocouple element 12 can be made of, for example, a nickel-chromium alloy for the plus element and a nickel alloy for the minus element, but is not particularly limited. In this example, only one pair of thermocouple wires 12 and 12 is accommodated, but a plurality of pairs may be inserted as a matter of course.

  In this example, as shown in FIG. 1, the sheath thermocouple 1 is mounted along the concave groove 10 up to a substantially half circumference position of the tube wall, and the half circumference position is measured by the hot junction 12a at the tip. In order to avoid the disturbance of the temperature distribution, the space of the concave groove 10 on the distal end side of the sheath thermocouple 1 must be closed. For this reason, for example, as shown in FIG. 3 (b), instead of the presser plate 2, a fitting plate 2A provided with a convex portion 21 to be fitted into the second storage groove on the inner surface side is prepared, and this is recessed. It is preferable to fit in the surplus space on the sheath thermocouple tip side of the groove 10, but such a fitting plate 2 </ b> A has a thermal conductivity different from that of the sheath thermocouple 1 and between the sheath thermocouple 1 tip. Since there is a possibility that a gap is generated, the temperature distribution is somewhat disturbed.

  Therefore, in this example, as shown in FIG. 3A, the dummy tube 4 in which the thermocouple element 12 and the inorganic insulator 13 are housed in the metal sheath 11 is connected to the distal end side of the sheath thermocouple 1 by welding. The connecting body 5 which is integrated and made up of the sheath thermocouple 1 and the dummy tube 4 is mounted over the entire circumference by the first storage groove 20 and the second storage groove 30. Such a dummy tube 4 can be joined to the tip of the sheath thermocouple 1 without a gap, and both have the same configuration and have substantially the same thermal conductivity. Disturbance can be avoided and the temperature measurement accuracy can be further improved.

  As shown in FIG. 4, the connecting body 5 composed of the sheath thermocouple 1 and the dummy tube 4 has at least the inside of the concave groove 10 using press dies 70 and 71 that match the shape of the storage grooves 20 and 30. The portion to be embedded in is pressure-deformed in advance into a flat cross-sectional structure over the entire length, and then fitted into and fitted between the first storage groove 20 and the second storage groove 30 of the concave groove 10 while striking the pressing plate 2, The pressed plate 2 is fixed to the tube wall W by Tig welding or laser welding.

  As described above, by performing the deformation using the press dies 70 and 71 in advance, the mounting work becomes easy and the adhesion can be reliably maintained. However, the present invention is not limited to this and is not deformed in advance. A sheath thermocouple having a circular cross section may be deformed by applying pressure at the time of mounting. Specifically, as shown in FIG. 5, the sheath thermocouple 1 having a circular cross section is pressed into the second storage groove 30 of the concave groove 10 by a method of pressurizing from the beginning with the pressing plate 2 or by roll compression. It may be inserted and further pressed down by the presser plate 2 and stored in a tight contact state between the first storage groove 20 and the second storage groove 30.

  Moreover, as shown in FIG. 6, it is also a preferred embodiment that the sheath thermocouple 1 has a double tube structure in which a soft metal layer 14 is provided on the outer periphery side of the sheath. Such a soft metal layer 14 can be deformed softly when the sheath thermocouple 1 is sandwiched between the storage grooves 20 and 30, and is interposed between the inner walls of the storage grooves 20 and 30 that contact each other. Even if there is a minute gap due to the roughness of the surface or the like, it can be filled to improve adhesion, and the contact thermal resistance at the contact portion can be reduced.

  As a material for such a soft metal layer 14, a material that has a small thermal resistance and has little influence on temperature measurement even if it is a double tube is more preferable. For example, it is preferable to employ copper (Cu), aluminum (Al), nickel (Ni) or the like as the soft metal material that is soft and has good heat transfer. Needless to say, when a dummy tube is connected to the distal end side, it is preferable to form a soft metal layer of the same material for the dummy tube. Such a double-pipe structure is formed by reducing the diameter of the long inner sheath 11 containing the thermocouple element 12 and the inorganic insulator 13 and forming the soft metal layer 14. It is inserted into the interior, and further, the diameter of the double pipe is integrally reduced to adjust to a predetermined diameter. In this diameter reduction processing, for example, it is preferable to pressurize the whole in the radial direction over the longitudinal direction of the sheath and then reduce the diameter to a predetermined diameter by drawing or swaging, thereby forming the inner sheath 11 and the soft metal layer 14. The outer sheaths are in close contact with each other.

  In this example, the sheathed thermocouple 1 to be embedded has a flat shape. However, depending on the size, as shown in FIG. 7, the sheathed thermocouple 1 having a circular section may be embedded in the same sectional shape. Further, as shown in FIG. 8, the sheath thermocouple 1 has a warm junction 12a in the middle of the sheath 11 in the axial direction, and the plus and minus strands 12 and 12 are directed toward both ends of the sheath from the warm contact 12a. It is also preferable to adopt a so-called “single-axis type” structure extending in opposite directions, and to attach the sheath thermocouple 1 along the concave groove 10 as shown in FIG. In this case, it is only necessary to set and arrange the hot junction at an appropriate position, it is possible to improve the measurement accuracy without the need to previously provide a dummy tube or the like, and the cross section becomes compact as shown in FIG. As a result, the disturbance of the temperature distribution is reduced and the width of the concave groove 10 and the holding plate 2 can be minimized and the cost can be reduced.

  Next, 2nd Embodiment is described based on FIGS.

  In this embodiment, as shown in FIGS. 11 and 12, instead of forming the second storage groove 30 on the bottom surface of the concave groove 10, the outer surface of the support plate 3 fitted to the bottom side of the concave groove 10 is used. The thermocouple 1 is sandwiched between the holding plate 20 and the storage grooves 20 and 30 of the support plate 3 and formed in a substantially central portion. In this example, as shown in FIG. 13, the sandwich body 6 is configured by sandwiching the sheath thermocouple 1 between the pressing plate 2 and the support plate 3 in advance and integrating them with each other by laser welding, particularly laser fine welding. Thereafter, the sandwiching body 6 is fitted into the concave groove 10. If the sandwiching body 6 is configured in this manner and then fitted into the concave groove 10, the attachment becomes easy and the adhesion can be reliably maintained. However, the attachment method is not particularly limited.

  In addition, after constructing such a sandwiching body 6, the dimensions may be adjusted by grinding both sides or one side of the pressing plate 2 and the supporting plate 3 according to the dimension of the concave groove 10 as necessary. And after the clamping body 6 is engage | inserted in the concave groove 10, it is fixed to the pipe wall W by Tig welding or laser welding similarly to 1st Embodiment. Since the other structure is basically the same as that of the first embodiment, the same structure is denoted by the same reference numeral, and the description thereof is omitted.

  Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and can of course be implemented in various forms without departing from the gist of the present invention.

  Next, based on the thermocouple mounting structure model shown in FIG. 15, a two-dimensional steady heat transfer analysis by a finite element method was performed using the material data and analysis conditions shown in Tables 1 and 2 below. Four conditions are set for the thermocouple embedded part gap: no gap, upper and lower gaps, only the lower side has a gap, and only the upper side has a gap, and the thickness direction of the tube wall for the dotted line part (thermocouple central part) in FIG. The temperature distribution at was determined.

As a result, in the case of no gap condition, the temperature linearly varies from the inner surface of the tube wall (temperature about 416 ° C) to the outer surface of the tube wall (temperature about 493 ° C) depending on the position (mm) in the tube wall thickness direction. An increasing distribution was shown. On the other hand, under the condition with a gap, as shown in FIG. 16, a temperature difference occurred as compared with the condition without a gap. Specifically, in the case where there is a gap between the upper and lower sides, and there is a gap only on the lower side, a temperature difference starts to occur around 4.5 mm, and a difference of about −0.4 ° C. at the thermocouple (embedding) depth position. became. In addition, in the condition where there was a gap only on the upper side, a large difference was not seen, but a slight temperature difference occurred from the vicinity past the thermocouple (embedding) depth position.
From the above, it can be seen that if there is a gap between the thermocouple and the storage groove, the temperature distribution is disturbed and the temperature measurement accuracy is lowered. In particular, in the case of a structure in which the lower gap is inevitable as in Patent Document 2, it can be expected that the temperature distribution is greatly disturbed.

1 is an overall view showing a thermocouple mounting structure according to a first embodiment of the present invention. It is sectional drawing which similarly shows the principal part of a thermocouple attachment structure, (a) shows a decomposition | disassembly state and (b) shows an assembly | attachment state. (A) is a longitudinal cross-sectional view which shows the coupling body which connected the dummy tube to the front-end | tip of a thermocouple, (b) is sectional drawing which shows the modification which attached the fitting board to the thermocouple front-end | tip side in a ditch | groove. Explanatory drawing which shows a mode that a thermocouple is beforehand processed into a flat cross section with a press die. Explanatory drawing which shows the modification which does not process a thermocouple beforehand in a flat cross section, but pressurizes simultaneously with the fitting of a pressing board, and makes it a flat cross section. It is sectional drawing which shows the modification which made the thermocouple the double tube structure, (a) shows a decomposition | disassembly state and (b) shows an assembly | attachment state. It is sectional drawing which shows the modification which incorporates the thermocouple of a circular cross section, (a) shows a decomposition | disassembly state, (b) shows an assembly | attachment state. (A), (b) is explanatory drawing which shows the example which made the sheath thermocouple the single axis | shaft type. The whole figure which similarly shows the attachment structure of a single axis | shaft type sheath thermocouple. Sectional drawing which shows the principal part of a thermocouple attachment structure similarly. The whole figure which shows the thermocouple attachment structure which concerns on 2nd Embodiment. Similarly, it is sectional drawing which shows the principal part of the thermocouple attachment structure of 2nd Embodiment, (a) shows a decomposition | disassembly state and (b) shows an assembly | attachment state. Explanatory drawing which shows a mode that a clamping body is comprised previously. (A), (b) is sectional drawing which shows the conventional thermocouple mounting structure, respectively. The figure which shows the model of the thermocouple attachment structure used for the two-dimensional steady heat transfer analysis. The graph which shows distribution of the temperature difference with no space | gap conditions about each condition.

Explanation of symbols

S Thermocouple mounting structure R1 Curved surface R2 Curved surface s1, s1 Clearance W Tube wall 1 Sheath thermocouple 1a Cross section outer half 1b Cross section inner half 2 Holding plate 2A Fitting plate 3 Support plate 4 Dummy tube 5 Connector 6 Holding body DESCRIPTION OF SYMBOLS 10 Concave groove 10c Bottom face 11 Metal sheath 12 Thermocouple element 12a Warm contact 13 Inorganic insulator 14 Soft metal layer 20 Storage groove 21 Convex part 30 Storage groove 70, 71 Press die 101 Thermocouple 102 Holding plate 110 Groove

Claims (8)

In the thermocouple mounting structure in which a concave groove is formed along the outer peripheral surface of the tube wall, and a sheath thermocouple is embedded in the concave groove,
While setting the concave groove to a predetermined width wider than the sheath diameter of the sheathed thermocouple built in,
Provide a pressing plate to be fitted in the groove,
Forming a first storage groove having a curved surface for storing the outer half of the sheath thermocouple in a substantially central portion on the inner surface side of the pressing plate without a gap;
A curved surface for accommodating the inner half of the sheath thermocouple, which is the remaining portion of the sheathed thermocouple, in a substantially central portion of the outer surface of the support plate fitted to the bottom surface of the concave groove or the bottom side of the concave groove without gaps. A thermocouple mounting structure to a tube wall, characterized in that a second storage groove provided with is formed.   The thermocouple mounting structure according to claim 1, wherein an outer surface of the pressing plate is set so as to be substantially flush with an outer peripheral surface of the tube wall in a state of being fitted in the concave groove.   The thermocouple mounting structure according to claim 1 or 2, wherein a sheath thermocouple is sandwiched between the pressing plate and the support plate, and then the sandwiched body is fitted into the concave groove.   The thermocouple mounting structure according to claim 3, wherein the holding plate and the support plate constituting the sandwiching body are integrated with each other by laser welding.   The concave groove is formed over the entire circumference of the outer peripheral surface of the tube wall, and the sheath thermocouple has a structure in which the plus and minus strands extend from the hot junction at the distal end to the same side toward the proximal end. A dummy tube containing a thermocouple wire and an inorganic insulator is connected to the distal end side of the sheath thermocouple, and a connecting body including the sheath thermocouple and the dummy tube is connected to the first storage groove and The thermocouple mounting structure according to any one of claims 1 to 4, wherein the thermocouple mounting structure is mounted over the entire circumference by the second storage groove.   The concave groove is formed over the entire circumference of the outer peripheral surface of the tube wall, and the sheath thermocouple is formed so that the plus and minus strands from the hot junction located in the middle of the sheath axial direction are opposite to each other toward the sheath ends. The thermocouple mounting structure according to any one of claims 1 to 4, wherein the thermocouple mounting structure has a structure extending to a side, and the sheath thermocouple is mounted over the entire circumference by the first storage groove and the second storage groove. .   The thermocouple mounting structure according to any one of claims 1 to 6, wherein the sheath thermocouple has a double tube structure in which a soft metal layer is provided on an outer peripheral side of the sheath.   The thermocouple mounting structure according to any one of claims 1 to 7, wherein the sheath thermocouple is mounted in a flat state in cross section, and the sheath thermocouple is pre-shaped in a flat state in cross section. A method of attaching a thermocouple to be mounted in the same flat inner space formed by the first storage groove and the second storage groove.

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