TW201502360A - Thermal insulating duct for high temperature gas - Google Patents

Abstract

A thermal insulating duct (10) includes a duct casing (18) having therein a high-temperature gas passage (8). The duct casing (18) includes a metallic liner member (32) exposed on the high-temperature gas passage (8), a metallic outer member (34) exposed on the ambient air and a flexible heat insulating material (36) interposed between the liner member (32) and the outer member (34). The metallic liner member (32) is engaged with the heat insulating material (36) and is axially movably connected to the outer member (34) via the heat insulating material (36). The metallic liner member (32) includes at opposite ends thereof an engagement part (44), which protrudes outwardly and is engaged with an end face (36a) of the heat insulating material (36).

Description

High temperature gas insulation conduit

The present invention relates to a heat insulating conduit for a high temperature gas, which is disposed between, for example, a gas turbine and a waste heat boiler.

Since the exhaust gas of the gas turbine is a high temperature of 500 ° C or higher and is a swirling flow, the exhaust pipe of the gas turbine is composed of a stainless steel plate or a molybdenum steel plate (SB material), and the so-called heat insulating material is laid on the outer side of the plate. External heat retainer. In the case of external insulation, construction of insulation materials must be carried out at the site (installation site). Specifically, in order to strengthen the fastening of the exhaust pipe flange, it is placed in the state where the heat insulating material is not placed until the test operation, and the reinforcing fastening is performed in the heating extension state during the test operation, and then the fastening is performed. Construction of insulation materials.

Therefore, the construction period at the site is prolonged, and since the exhaust pipe, the bolt hole, and the like are rusted during the placement period before the test operation, it is necessary to take measures to suppress rust, which is laborious. Further, regarding the mute technique, the fiber absorbing material is attached to the silent casing, and is coated on the surface of the sound absorbing material with a perforated plate or a wire mesh (for example, Japanese Patent Laid-Open Publication No. Hei. [Progress Technical Literature] [Japanese Patent Literature]

Japanese Patent Document 1: Japanese Patent No. 3073420

In addition, if it is a gas-electric symbiosis device, the internal pressure of the exhaust gas is as high as 0.25KpaG due to the pressure loss of the waste heat boiler, etc., and it is a rotating flow of high temperature, so it may be the welded portion of the exhaust pipe on the inlet side of the waste heat boiler. Cracks appear on it. In addition, in the case of operation, such as "operation to start and stop daily" or "operation to start and stop every other week", especially the repeated load of the telescopic load or residual stress caused by heat, The exhaust pipe material itself is deteriorated, and high temperature cracking occurs in addition to the welded portion. Therefore, such a weld rupture, high temperature cracking, or the like is avoided by applying a castable refractory mud (refractory material) or a ceramic heat insulating material inside the exhaust pipe.

[The subject to be solved by the invention]

However, the castable refractory mud is easily damaged due to its non-vibration resistance, so if it is applied to the exhaust pipe of the gas turbine, it may fall off. Further, the internal heat insulating structure using the ceramic heat insulating material is applied to a conduit through which the rectified exhaust gas flows, a conduit through which a sufficient internal area and a low flow rate exhaust gas flow, but a flow rate such as a gas turbine outlet is generally In the case of a swirling flow of about 100 m/s, the exhaust gas may enter a space in which a ceramic plate is pressed and laminated to form a tile-like plate (constituting a plate that can be slid in consideration of thermal elongation). As a result, it may cause deformation or peeling of the board, or the heat insulating material may be sucked away and scattered.

In view of the above problems, an object of the present invention is to provide a heat-insulating conduit for a high-temperature gas, which can prevent the construction of a heat insulating material on site, and can suppress welding cracking, high-temperature cracking, peeling, and the like. [Means for solving the problem]

In order to achieve the above object, in the high temperature gas heat insulating pipe of the present invention, the case for forming the high temperature gas passage has an inner layer member made of a metal plate exposed to the high temperature gas passage, an outer layer member made of a metal plate, and the insertion. a flexible heat insulating material interposed therebetween, wherein the inner layer member is fastened to the heat insulating material, and the heat insulating material is coupled to the outer layer member in a relatively movable manner, and is disposed at an end portion of the inner layer member a fastening piece that protrudes outward and is fastened to the end surface of the heat insulating material.

According to this configuration, since the casing forming the high-temperature gas passage is in a so-called internal heat insulation method (that is, having an inner layer member made of a metal plate exposed to the high-temperature gas passage, an outer layer member exposed to the outer air metal plate, and the insert The flexible insulation material is located between them, so the construction of the insulation material can be carried out at the factory without the need for construction of the insulation material and rust prevention work on site. Moreover, since it is not necessary to apply a refractory material or a heat insulating material to the inside of the casing, there is no such situation that it falls off or peels off. Further, since the outer layer member constituting the periphery of the heat insulating pipe is not exposed to the high temperature gas, deterioration of the flange portion, the sealing portion, and the like provided in the outer layer member or generation of high temperature cracking can be suppressed.

Further, since the outer layer member is not exposed to the high-temperature gas, it is not necessary to use a high-priced heat-resistant metal such as a stainless steel plate or a molybdenum steel plate, and the heat insulating pipe can be manufactured at low cost as a whole. Furthermore, the inner layer member is buckled to the heat insulating material and is coupled to the outer layer member by the heat insulating material in a relatively movable manner, so that in addition to suppressing the thermal stress generated by the inner layer member, the contact with the high temperature gas can be suppressed. At the point where the weld is broken due to the loss of the welded portion. Moreover, the end piece of the inner layer member is provided with a snap piece which protrudes outward and is fastened to the end surface of the heat insulating material, so that the structure can be simplified, and the inner layer member can be relatively moved without providing a welded portion. Attach to the outer member.

In the present invention, the inner portion of the snap piece of the inner layer member has an overlapping portion which is folded and overlapped, and the outer side portion of the snap tab is preferably fixed to the outer layer member. According to this configuration, the thermal elongation of the inner layer member can be absorbed by the deformation of the overlapping portion.

In the present invention, the casing is connected by a flat upper wall, a lower wall and a pair of side walls to form the high temperature gas passage having a rectangular cross section, and the inner layer member of the walls preferably is made of the heat insulating material. The outer layer member is joined in a relatively movable manner. According to this configuration, since the walls are in the form of a flat plate, the manufacture is easier.

In the case where the casing forms a high-temperature gas passage having a rectangular cross section, the inner portion of the snap member of the inner layer member preferably has an overlapping portion formed by bending and overlapping, and a gap between adjacent walls. The overlapping portion and the heat insulating cushioning material located outside thereof are disposed. According to this configuration, in addition to the deformation of the inner layer member by the overlapping portion, the heat insulating cushioning material can be utilized to absorb the heat elongation between the walls and block the heat transfer.

In the case where the heat insulating cushioning material is provided, it is preferable to provide a pressing member which is elastically fitted to the inside of the heat insulating cushioning material and which can block the high temperature gas and define the position of the heat insulating cushioning material. According to this configuration, the pressing member can prevent the high-temperature gas from directly hitting the heat insulating cushioning material and damage the insulating cushioning material, and the heat insulating cushioning material can be held at an appropriate position.

In the present invention, the inner layer member is preferably fastened to the outer layer member at an intermediate portion between the opposite ends. According to this configuration, since the intermediate portion is fastened, the expansion of the inner side member to the inner layer member due to thermal expansion can be effectively suppressed. Moreover, by using the fastening portion as one of the intermediate portions, the heat transfer to the outer layer member via the fastening member can be minimized. Further, by this fastening, it is possible to prevent the inner layer member from being largely deformed to the inside due to the thickness of the heat insulating material which becomes the upper wall of the top surface, or to move downward due to the offset of the heat insulating material.

Any combination of at least two of the claims and/or the description and/or the drawings are also included in the present invention. In particular, any combination of two or more of the claims of the claims is also included in the present invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. Fig. 1 is a schematic block diagram showing a gas-electricity symbiosis system using a gas turbine. This system uses the driving force of the gas turbine GT to rotate the rotor of the generator G via the speed reducer R/G to obtain electric power. The gas turbine GT includes a compressor 2, a combustor 4, and a turbine 6, and the exhaust gas E discharged from the gas turbine GT is discharged to the outside through a high-temperature gas passage 8 as an exhaust passage.

In detail, at the exhaust outlet of the gas turbine GT, the heat insulating duct 10 constituting a part of the high temperature gas passage 8 is connected; on the downstream side of the heat insulating duct 10, the waste heat boiler 12 is connected; on the downstream side of the waste heat boiler 12, The economizer 14 is connected. The water supplied to the economizer 14 is preheated by the exhaust gas E, supplied to the waste heat boiler 12, and vaporized. The steam from the waste heat boiler 12 is utilized by, for example, an absorption chiller or a heat source for generating warm water. The exhaust gas E that has been heat recovered by the waste heat boiler 12 and the economizer 14 is released into the air through the exhaust pipe 16.

As shown in FIG. 2, the insulated conduit 10 for high temperature has a housing 18 that forms part of the high temperature gas passage 8. As shown in Fig. 4, the casing 18 is connected by a flat upper wall 20, a lower wall 22, and a pair of side walls 24, 24 to form a high temperature gas passage 8 having a rectangular cross section.

As shown in Fig. 3, the passage area of the high temperature gas passage 8 in the casing 18 increases toward the downstream direction. At the upstream end of the casing 18, a cylindrical inlet pipe 26 is joined by welding, and a flange-like first flange 28 is welded to the upstream end portion of the inlet pipe 26. In the first flange 28, a plurality of bolt insertion perforations (not shown) are arranged in the circumferential direction.

At the downstream end of the casing 18, the flange-like second flange 30 is welded to the flange. In the second flange 30, a plurality of bolt insertion holes (not shown) are arranged in the circumferential direction. The first flange 28 is coupled to the exhaust outlet of the gas turbine GT of FIG. 2 by a bolt (not shown), and the second flange 30 is coupled to the inlet of the boiler 14.

As shown in FIG. 4, in each of the walls 20, 22, 24, the housing 18 has: an inner layer member 32 made of a metal plate exposed to the high temperature gas passage 8, and a metal plate outer layer member 34 exposed to the outside air; And a heat insulating material 36 interposed therebetween.

The inner layer member 32 is made of a metal having high heat resistance such as a stainless steel plate or a molybdenum steel plate. In the present embodiment, it is made of SUS304 having a thickness of 2 mm. The outer layer member 34 is made of a steel material for a general structure of low cost, and is made of SS400 having a thickness of 6 mm in this embodiment. The outer surface of the outer layer member 34 is coated with a rust preventive coating.

As shown in FIG. 5, the heat insulating material 36 includes the innermost first heat insulating layer 38, the outer second insulating layer 40, and the outermost third heat insulating layer 42 on the outer side. In the present embodiment, the first heat insulating layer 38 is made of a ceramic fiber having high heat insulating properties, and the second heat insulating layer 40 and the third heat insulating layer 42 are made of inexpensive rock wool. By providing the heat insulating material 36 with a multilayer structure, it is possible to arrange a heat insulating material having a high heat insulating property on the inside of the high temperature, and to arrange an inexpensive heat insulating material on the outer side of the lower temperature, thereby effectively insulating the heat, and overall It can reduce the cost of insulation materials. The heat insulating material 36 may be two or more layers, or may be a single layer.

The end portions 32a of the four sides of the inner layer member 32 are respectively formed to form a snap piece 44 which protrudes outward, and the inner layer member 32 is obtained by snapping the snap piece 44 to the end surface 36a of the heat insulating material 36. The heat insulating material 36 is coupled so as to be relatively movable in the parallel direction with respect to the outer layer member 34. The outer end portion 44a of the snap tab 44 is fixed to the outer layer member 34 by welding.

The snap piece 44 has an overlapping portion 50 which is formed by folding and folding a steel plate. In detail, the end portion 32a of the inner layer member 32 is bent outwardly and then folded back toward the inside, and then bent outward to form a three-layer overlapping portion 50, the front end of which overlaps to the outside. A snap tab 44 is formed. Thereby, as shown by the two-dotted line, even when the inner layer member 32 is thermally extended, the overlapping portion 50 is deformed and stretched to absorb the heat elongation.

As shown in FIG. 4, the inner layer member 32 is fastened to the outer layer member 34 by the fastening member 52 at the intermediate portion 32b between the opposite end portions 32a, 32a. In detail, as shown in FIG. 6, an opening 54 is formed in the intermediate portion 32b of the inner layer member 32, and the opening 54 is inserted through the full-threaded bolt 58 without a head, and the outer end of the full-threaded bolt 58 is fixed by welding W. In the outer member 34. The liner plates 56, 56 are brought into contact with the inner side and the outer side of the inner layer member 32 to cover the inner end portion of the full threaded bolt 58. In this state, the inner end portion of the full-threaded bolt 58 is penetrated, and the nut 60, 60 is screwed from the inner side and the outer side to the inner end portion, and by the fastening force of the nut 60, 60, the cushion plate 56, 56 is used. The inner layer member 32 is held.

Thereby, the inner layer member 32 is fastened to the outer layer member 34 via the fully threaded bolts 58 and the nuts 60, 60. That is, the fully threaded bolt 58 and the two nuts 60, 60 constitute the fastening member 52.

Fig. 7 shows the joint between the lower wall 22 and the side wall 24. The upper surface 22a of the lower wall 22 and the lower end surface 24a of the side wall 24 are opposed to each other via the first gap S1. Further, the outer layer member 34 of the side wall 24 is formed with an extended portion 64 extending downward. The extension portion 64 extends downward from the outer side of the outer end surface 22b of the lower wall 22, and is joined to the outer layer member 34 of the lower wall 22 by welding. This joint portion is reinforced by welding of the reinforcing plate 66. A second gap S2 is formed between the extension portion 64 and the outer end surface 22b of the lower wall 22, and the second gap S2 communicates with the first gap S1.

The overlapping portion 50 of the side wall 24 is disposed in the first gap S1, and the overlapping portion 50 of the lower wall 22 is disposed in the second gap S2. Further, the heat insulating cushioning material 68 is disposed outside the overlapping portion 50 of the side wall 24 in the first gap S1 (on the right side in FIG. 7). The thermal barrier material 68 is a ceramic coating.

The pressing member 70 is disposed on the outer side of the overlapping portion 50 of the side wall 24 in the first gap S1 and inside the heat insulating cushion member 68. The pressing member 70 is configured by bending a spring steel plate into a V shape. The pressing member 70 is elastically fitted inside the heat insulating cushion member 68 in the first gap S1, and the high temperature gas can be prevented from directly contacting the heat insulating cushion member 68, and the position of the heat insulating cushion member 68 can be defined. By the overlapping portion 50 of the side wall 24, the pressing member 70 can be prevented from being loosened to the high temperature gas passage 8.

Fig. 7 shows the joint between the lower wall 22 and the side wall 24, and the joint between the other adjacent walls is also of the same configuration. Thus, the casing 18 has a structure in which the inner layer member 32 and the outer layer member 34 do not have a large area contact. As a result, in the high-temperature gas passage 8, although the temperature of the exhaust gas E exceeds 550 ° C, the surface temperature of the outer layer member 34 exposed to the outside air can be maintained at less than 70 ° C.

Figure 8 shows the joint between the lower wall 22 of the housing 18 and the inlet tube 26. The inlet pipe 26 is also identical to the casing 18, and has an inner layer member 72, an outer layer member 74, and a three-layer heat insulating material 76. Endless snap members 69, 69 are coupled to both ends of the inner layer member 72. The first flange 28 is welded to the upstream end portion 74a of the outer layer member 74 of the inlet pipe 26 by welding. The first flange 28 is not in contact with the snap member 69. The outer peripheral portion of the outer peripheral surface of the outer layer member 74 is on the upstream side, and the flange-like projections 78 are fixed by welding.

The upstream end surface 22c of the lower wall 22 of the casing 18 and the downstream end surface 26a of the inlet pipe 26 are opposed to each other via the third gap S3. Further, the outer layer member 34 of the lower wall 22 is formed with an extended portion 80 extending toward the upstream side, and the extended portion 80 is fixed to the projection 7 of the outer layer member 74 of the inlet pipe 26 by welding.

In the third gap S3, the overlapping portion 50 of the lower wall 22 is disposed, and the above-described heat insulating cushion member 68 is disposed on the outer side. Further, the pressing member 70 described above is disposed on the outer side of the overlapping portion 50 of the lower wall 22 in the third gap S3 and inside the heat insulating cushion member 68. The reinforcing member 82 is fixed to the outer peripheral surface of the outer layer member 34 of the lower wall 22 at a position corresponding to the third gap S3. Fig. 8 shows the joint between the lower wall 22 and the inlet pipe 26, and the joint between the other walls 20, 24 and the inlet pipe 26 has the same configuration.

Figure 9 shows the joint between the upper wall 20 of the casing 18 and the inlet of the waste heat boiler 12. The second flange 30 is welded to the downstream end portion of the outer layer member 34 of the outer wall member 20, and the outer surface thereof is reinforced by the reinforcing member 84. The second flange 30 is not in contact with the inner layer member 32.

The downstream end surface 20a of the upper wall 20 and the upstream end surface 12a of the inlet of the waste heat boiler 12 are opposed to each other via the fourth gap S4. In the fourth gap S4, the overlapping portion 50 of the upper wall 20 is disposed, and the above-described heat insulating cushion member 68 is disposed on the outer side. Further, the pressing member 70 described above is disposed on the outer side of the overlapping portion 50 of the upper wall 20 in the fourth gap S4 and inside the heat insulating cushion member 68.

Fig. 9 shows the joint between the upper wall 20 and the inlet of the waste heat boiler 12, and the joint between the other walls 22, 24 and the inlet of the waste heat boiler 12 is also of the same configuration. Thus, the first and second flanges 28 and 30 are welded to the low temperature outer layer members 74 and 34 between the first and second flanges 28 and 30 and the high temperature inner layer members 72 and 32 and the high temperature gas passage 8 . The heat insulating materials 76 and 36 and the heat insulating cushioning material 68 are interposed. Further, the inner layer members 72 and 32 which are high temperatures have no welded portion. That is, the inner layer members 32, 72 are heat-resistant members particularly for high-temperature gases; the outer layer members 34, 74 are members for securing the strength of the catheter.

In the above configuration, the casing 18 forming the high-temperature gas passage 8 shown in FIG. 4 has an inner layer member 32, an outer layer member 34, and a heat insulating material 36 interposed therebetween, which is constituted by so-called internal heat insulation. The construction of the heat insulating material 36 can be carried out at the factory without the need to carry out the construction of the heat insulating material 36 on site. As a result, there is no difference in construction quality due to differences in skill of the field operator, and the quality of the insulated duct 10 can be ensured. Moreover, since it is not placed on the site before the test operation, it is possible to suppress rust such as bolt holes. In addition, there is no need to apply a refractory material or a heat insulating material inside the casing 18, so that there is no such peeling or peeling.

Further, since the outer layer member 34 does not touch the high temperature gas, deterioration of the first and second flange portions 28, 30 or the sealing member can be suppressed. Further, since the outer layer member 34 does not touch the high-temperature gas, the outer layer member 34 does not need to use a high-priced heat-resistant metal such as a stainless steel plate or a molybdenum steel plate, and as a whole, the heat insulating pipe 10 can be manufactured at a low price. Further, since the inner layer member 32 is fastened to the heat insulating material 36 and is coupled to the outer layer member 34 in a relatively movable manner by the heat insulating material 36, it can suppress the thermal stress generated by the inner layer member 32. At the point of contact with the high temperature gas, the weld is broken due to the loss of the welded portion.

At the end portion 32a of the inner layer member 32 of FIG. 5, a snap tab 44 is provided. The snap tab 44 has an overlapping portion 50 which is folded and overlapped, and the outer side portion of the snap tab 44 is fixed to the outer layer member 34. Thereby, the inner layer member 32 is coupled to the outer layer member 34 in a relatively movable manner by the heat insulating material 36 without using a welded portion by a simple structure. Moreover, by providing the overlapping portion 50, the thermal elongation of the inner layer member 32 can be absorbed. Further, since the walls 20, 22, and 24 of the casing 18 have a flat shape, the manufacturing becomes easy.

Further, since the outer side portion of the snap tab 44 is fixed to the outer layer member 34, the high-temperature exhaust gas E can be prevented from flowing into the heat insulating material 36 from the gap between the heat insulating pipe 10 and the gas turbine GT or the waste heat boiler 12. Thereby, it is possible to prevent the temperature of the outer layer member 34 from rising due to the exhaust gas E flowing into the heat insulating material 36, so that the heat insulating effect can be enhanced.

As shown in FIG. 7, in the first gap S1 between the adjacent walls 20, 22, and 24 in the casing 18, the overlapping portion 50 and the heat insulating cushion member 68 located outside thereof are disposed, so that the overlapping portion 50 can absorb the inside. The deformation of the layer member 32 and the use of the thermal barrier material 68 absorbs the thermal elongation of the walls 20, 22, 24 and resists heat transfer.

Further, since the pressing member 70 is fitted to the outside of the overlapping portion 50 in the first gap S1 and inside the heat insulating cushion member 68, the blocking of the high-temperature gas and the position of the heat insulating cushion member 68 can be achieved.

The inner layer member 32 of Fig. 4 is fastened to the outer layer member 34 at the intermediate portion 32b between the end portions 32a and 32a, so that the inner layer member 32 can be effectively suppressed from expanding inward due to thermal expansion. Further, by using the fastening portion as one of the intermediate portions 32b, heat transfer to the outer layer member 34 via the fastening member 52 can be suppressed to a minimum. Further, by the fastening, the inner layer member 32 can be prevented from being deformed by the thickness of the heat insulating material 36 which becomes the top surface of the top surface 20, and the heat insulating material 36 can be prevented from shifting obliquely. Move below (on the right side of Figure 2).

The present invention is not limited to the above embodiments, and various additions, changes, or deletions may be made without departing from the scope of the invention. For example, in the above embodiment, in each of the walls 20, 22, and 24, the inner layer member 32 is coupled to the outer layer member 34 by the heat insulating material 36 so as to be relatively movable, as long as at least the walls 20, 22, and 24 are provided. In the first embodiment, the inner layer member 32 may be coupled to the outer layer member 34 by the heat insulating material 36 so as to be relatively movable. Therefore, such a design is also included in the scope of the present invention.

2‧‧‧Compressor
4‧‧‧ burner
6‧‧‧ Turbine
7‧‧‧
8‧‧‧High temperature gas path
10‧‧‧Insulation catheter
12‧‧‧Waste heat boiler
12a‧‧‧ upstream end face
14‧‧‧heater
16‧‧‧Exhaust pipe
18‧‧‧Shell
20‧‧‧Upper wall
20a‧‧‧ downstream end face
22‧‧‧ Lower wall
22a‧‧‧above
22b‧‧‧Outside end face
22c‧‧‧ upstream end face
24‧‧‧ side wall
24a‧‧‧ lower end
26‧‧‧Inlet pipe
26a‧‧‧ downstream end face
28‧‧‧1st flange
30‧‧‧2nd flange
32‧‧‧ Inner structural components
32a‧‧‧End
32b‧‧‧Intermediate
34‧‧‧ outer members
36‧‧‧Insulation
36a‧‧‧ end face
38‧‧‧1st insulation layer
40‧‧‧2nd insulation layer
42‧‧‧3rd insulation layer
44‧‧‧Snap pieces
44a‧‧‧Outer end
50‧‧‧ overlap
52‧‧‧Snap members
54‧‧‧ openings
56‧‧‧ liner board
58‧‧‧Full threaded bolt
60‧‧‧ nuts
64‧‧‧Extension
66‧‧‧ reinforcing plate
68‧‧‧Insulation cushioning material
69‧‧‧Snap members
70‧‧‧ Pushing members
72‧‧‧ Inner structural components
74‧‧‧ outer members
74a‧‧‧ upstream side
76‧‧‧Insulation
78‧‧‧ protrusion
80‧‧‧Extension
82‧‧‧Reinforcing components
84‧‧‧Reinforcing components
E‧‧‧Exhaust
G‧‧‧Generator
GT‧‧‧ gas turbine
R/G‧‧‧ reducer
S1‧‧‧ first gap
S2‧‧‧ second gap
S3‧‧‧3rd gap
S4‧‧‧4th gap
W‧‧‧Welding

The invention will be apparent from the following description of the preferred embodiments. However, the embodiments and the drawings are only intended to be illustrative and illustrative, and not to limit the scope of the invention. The scope of the invention is defined by the scope of the appended claims. In the drawings, the same component numbers in the plural figures show the same or equivalent parts. Fig. 1 is a schematic configuration diagram of a gas turbine system including a heat-insulating conduit for a high-temperature gas according to a first embodiment of the present invention. [Fig. 2] A side view of the same insulated pipe. [Fig. 3] A longitudinal sectional view of the same insulated pipe. Fig. 4 is a sectional view taken along line IV-IV of Fig. 2; Fig. 5 is an enlarged cross-sectional view showing the vicinity of an end portion of the upper wall of the casing of Fig. 4. Fig. 6 is an enlarged cross-sectional view showing a portion VI of Fig. 4. Fig. 7 is a sectional view taken along line VII-VII of Fig. 2; Fig. 8 is an enlarged cross-sectional view showing a portion VIII of Fig. 3. Fig. 9 is an enlarged cross-sectional view showing the IX portion of Fig. 3.

18‧‧‧Shell

20‧‧‧Upper wall

32‧‧‧ Inner structural components

32a‧‧‧End

34‧‧‧ outer members

36‧‧‧Insulation

36a‧‧‧ end face

38‧‧‧1st insulation layer

40‧‧‧2nd insulation layer

42‧‧‧3rd insulation layer

44‧‧‧Snap pieces

44a‧‧‧Outer end

50‧‧‧ overlap

Claims (6)

A heat-insulating conduit for forming a high-temperature gas, wherein a casing for forming a high-temperature gas passage has an inner layer member made of a metal plate exposed to the high-temperature gas passage, an outer layer member made of a metal plate, and an outer layer member and the outer layer interposed therebetween a heat insulating material between the members; the inner layer member is fastened to the heat insulating material, and the heat insulating material is coupled to the outer layer member in a relatively movable manner; at an end portion of the inner layer member, a snap tab that protrudes outward and is fastened to the end surface of the heat insulating material. The heat-insulating conduit of the high-temperature gas of the first aspect of the invention, wherein the inner portion of the fastening piece of the inner layer member has an overlapping portion which is folded and overlapped, and the outer side portion of the fastening piece is fixed to the outer layer member. The heat insulating pipe of the high temperature gas of claim 1 or 2, wherein the casing is connected by a flat upper wall, a lower wall and a pair of side walls, and the high temperature gas passage having a rectangular cross section is formed; The inner layer member in the wall is joined to the outer layer member in a relatively movable manner by the heat insulating material. The heat-insulating conduit of the high-temperature gas of the third aspect of the invention, wherein the inner portion of the fastening piece of the inner layer member has an overlapping portion formed by bending and overlapping, and the overlapping is disposed in a gap between adjacent walls. And an insulation cushioning material located on the outside. The heat insulating pipe of the high temperature gas of the fourth aspect of the patent application, further comprising a pressing member attached to the inner side of the heat insulating cushioning material, elastically embedded in the gap, and blocking the high temperature gas and defining the heat insulating cushioning material The location. The heat-insulating conduit for a high-temperature gas according to any one of claims 1 to 5, wherein the inner layer member is fastened to the outer layer member at an intermediate portion between the opposite ends.