WO2019013150A1

WO2019013150A1 - Boiler furnace wall replacing method and boiler furnace wall temporary holding structure

Info

Publication number: WO2019013150A1
Application number: PCT/JP2018/025825
Authority: WO
Inventors: 悠一郎安島; 誠坂本
Original assignee: 三菱日立パワーシステムズ株式会社
Priority date: 2017-07-10
Filing date: 2018-07-09
Publication date: 2019-01-17
Also published as: KR20200028384A; PH12020500071A1; JP2019015481A; JP6687566B2

Abstract

According to the present invention, a boiler device is provided with: a boiler furnace wall that has a vertical tube wall located in the upper part and a spiral tube wall 3 located in the lower part; a back stay that is disposed so as to surround the spiral tube wall 3 and holds the furnace pressure; and a support member 8 that is fixed to the vertical tube wall and supports the back stay. After the spiral tube wall 3 below a portion of a furnace wall section 30 is fixed to the support member 8 and temporarily held, the outer edge of the portion of the furnace wall section 30 is cut and the portion of the furnace wall section 30 is removed from the spiral tube wall 3, and a replacement furnace wall section 31 is joined to the peripheral edge of an opening 35 of the spiral tube wall 3 formed as a result of the removal, so as to close the opening 35.

Description

Replacement method of boiler furnace wall and temporary holding structure of boiler furnace wall

The present invention relates to a method of replacing a boiler furnace wall in a boiler apparatus and a temporary holding structure of the boiler furnace wall.

Patent Document 1 describes a combined water-cooled wall structure in which the upper part of the furnace is formed by vertical water-cooled walls in which water pipes and fins are alternately welded and the lower part of the furnace is formed by inclined water-cooled walls (spiral furnace wall structure) There is. The inclined water-cooled wall is a membrane wall in which water pipes and fins are alternately welded in the same manner as the vertical water-cooled wall, and is supported by being suspended from the vertical water-cooled wall.

Further, the support member is disposed vertically to the inclined water-cooling wall, and the panel-side support fitting is joined to the inclined water-cooling wall. Holes on the panel side support bracket pass through the presser pin, and the panel side support bracket and the presser pin extend in the lateral direction of the inclined water-cooled wall and the vertical direction of the support member in the space defined by the panel side support bracket and the presser pin. It functions as a support fitting that can absorb elongation.

Japanese Patent Application Laid-Open No. 60-164103

In a large coal-fired large variable flow once-through boiler, the progress of NOx reduction significantly reduces the vicinity of the furnace wall of the furnace to a reducing atmosphere and causes sulfidation corrosion in the water pipes (heat transfer pipes) that constitute the furnace wall. Such sulfidation corrosion has become remarkable in recent years, and in order to prevent leaks (water leakage, leaked water vapor) from water pipes, partially cut out the corroded furnace wall using the time of inspection conducted regularly. It will be necessary to replace it with an uncorroded furnace wall.

However, in the boiler apparatus of Patent Document 1, the spiral pipe wall (inclined water-cooled wall) is formed by the membrane wall in which the water pipe extending obliquely with respect to the direction of gravity and the fins are welded and joined. It is inevitable that the strength is lower than that of the pipe wall (vertical water-cooled wall). Also, the load of the spiral pipe wall is transmitted to the vertical pipe wall by the spiral pipe wall itself without being transmitted to the upper vertical pipe wall by the support member. For this reason, when the corroded furnace wall portion of the spiral pipe wall is cut out to provide a wide opening in the spiral pipe wall, there is no part transmitting the load under the opening to the upper side of the boiler, so that the load is on both sides of the opening. By acting on the portion, stress concentration occurs, and there is a possibility that the spiral tube wall may be deformed or damaged.

Therefore, in the present invention, when replacing a part of the furnace wall part of the spiral pipe wall with a furnace wall part for replacement, it is possible to prevent the generation of deformation and damage of the spiral pipe wall. The purpose is to provide a replacement method and a temporary holding structure for the boiler furnace wall.

In order to achieve the above object, according to a first aspect of the present invention, a boiler furnace wall having an upper vertical pipe wall and a lower spiral pipe wall suspended from the vertical pipe wall is disposed around the spiral pipe wall. Boiler apparatus including a back stay for supporting the furnace pressure and a support member fixed to the vertical pipe wall and supporting the back stay, the support member hanging near the outer surface of the spiral pipe wall without being fixed to the spiral pipe wall A boiler furnace wall replacement method in which a furnace wall portion of a portion of the spiral pipe wall is replaced with a furnace wall portion for replacement, including a temporary holding step, a cutting-out step, and an attaching step.

In the temporary holding step, the spiral pipe wall below the part of the furnace wall portion is fixed to the support member and temporarily held. In the cutout step, after the temporary holding step, the outer edge of the portion of the furnace wall portion is cut to extract the portion of the furnace wall portion from the spiral pipe wall. In the mounting step, the replacement furnace wall portion is joined to the peripheral portion of the opening so as to close the opening of the spiral pipe wall formed in the cutting step.

In the above-mentioned construction method, when partially cutting out a part of the furnace wall portion of the spiral furnace wall and replacing it with a replacement furnace wall portion, before cutting out a part of the furnace wall portion, the partial furnace wall portion Since the spiral pipe wall below the wall portion is fixed and temporarily held to the support member, the spiral below the opening is formed in a state where a wide opening is formed in the spiral pipe wall by cutting out a part of the furnace wall portion The load of the tube wall is transmitted to the vertical tube wall via the support member. Therefore, stress concentration on both sides of the opening can be alleviated, and deformation and damage of the spiral tube wall can be prevented.

A second aspect of the present invention is the boiler furnace wall replacement method according to the first aspect, further including a temporary holding releasing step of releasing temporary holding of the spiral pipe wall with respect to the support member after the attaching step.

In the above construction method, after the furnace wall portion for replacement is joined to the peripheral portion of the opening so as to close the opening of the spiral pipe wall, the temporary holding of the spiral pipe wall with respect to the support member is released. Unnecessary interference between the spiral tube wall and the support member can be prevented, and the support member can be functioned as well as before replacement even after replacement of the furnace wall portion.

A third aspect of the present invention is the boiler furnace wall replacement method according to the second aspect, wherein in the temporary holding step, the first temporary holding member is fixed to the spiral pipe wall, and the second temporary holding member is fixed to the support member. The spiral pipe wall is temporarily held by welding and fixing the holding member and welding and fixing the first temporary holding member to the second temporary holding member. In the temporary holding release step, the weld between the support member and the second temporary holding member and the weld between the first temporary holding member and the second temporary holding member are cut off, and the support member and the first temporary holding member The temporary holding of the spiral pipe wall is released by removing the second temporary holding member from the above.

In the above construction method, in the temporary holding step, the first temporary holding member fixed to the spiral pipe wall is welded and fixed to the second temporary holding member fixed by welding to the support member, and in the temporary holding releasing step Cutting the welded portion between the support member and the second temporary holding member and the welded portion between the first temporary holding member and the second temporary holding member, and from the support member and the first temporary holding member to the second temporary holding Since the temporary holding of the spiral pipe wall is released by removing the member, the temporary holding of the spiral pipe wall can be released by a simple operation. Further, since the first temporary holding member is left on the spiral pipe wall side, damage to the spiral pipe wall due to temporary holding release can be reliably prevented. Furthermore, since the second temporary holding member is removed, unnecessary interference between the spiral pipe wall and the support member during operation of the boiler apparatus can be reliably prevented.

A fourth aspect of the present invention is a boiler furnace wall having an upper vertical pipe wall and a lower spiral pipe wall suspended from the vertical pipe wall, and a back disposed around the spiral pipe wall to support furnace pressure In a boiler apparatus including a stay and a support member fixed to the vertical pipe wall and supporting the back stay, the support member hanging near the outer surface of the spiral pipe wall without being fixed to the spiral pipe wall, the spiral pipe wall A temporary holding structure of a boiler furnace wall in which a spiral pipe wall is temporarily held by a support member when replacing a part of the furnace wall portion with a furnace wall portion for replacement, the first holding structure fixed to the spiral pipe wall A temporary holding member and a second temporary holding member fixed to the support member by welding are provided. The first temporary holding member is fixed to the second temporary holding member by welding.

In the above configuration, when partially cutting out the furnace wall portion of the spiral furnace wall and replacing it with a replacement furnace wall portion, before cutting out the partial furnace wall portion, the partial furnace wall portion Since the lower spiral pipe wall of the wall portion is fixed to and temporarily held by the support member, the cutout of a part of the furnace wall portion lowers the opening in a state where a wide opening is formed in the spiral pipe wall. The load on the spiral tube wall is transmitted to the vertical tube wall via the support member. Therefore, stress concentration on both sides of the opening can be alleviated, and deformation and damage of the spiral tube wall can be prevented.

In addition, the first temporary holding member is fixed to the spiral pipe wall, the second temporary holding member is fixed to the support member by welding, and the first temporary holding member is fixed to the second temporary holding member by welding. After completion of the replacement work, the weld between the support member and the second temporary holding member and the weld between the first temporary holding member and the second temporary holding member are cut off, and the support member and the first temporary hold By removing the second temporary holding member from the member, temporary holding of the spiral pipe wall can be released by a simple operation. In addition, since the second temporary holding member may be removed while the first temporary holding member remains on the spiral pipe wall side, damage to the spiral pipe wall due to temporary holding release can be reliably prevented. Furthermore, by removing the second temporary holding member, unnecessary interference between the spiral pipe wall and the support member at the time of operation of the boiler apparatus can be reliably prevented.

According to the present invention, when replacing a part of the furnace wall part of the spiral pipe wall with a furnace wall part for replacement, it is possible to prevent the generation of deformation and damage of the spiral pipe wall.

It is a figure which shows the water-cooled wall structure of the boiler furnace which concerns on one Embodiment of this invention, (a) is a side view, (b) is a top view. It is a principal part enlarged view of a spiral pipe wall, (a) is a side view of a portion including a panel side support bracket, (b) is a IIb direction arrow view of Drawing 2 (a). It is III direction arrow line view of Fig.2 (a). It is a perspective view showing an example of a back stay. It is a side view which shows the state which hold | maintained the downward direction of the furnace wall part of exchange object temporarily. It is the top view which looked the temporary holding state of the spiral tube wall with respect to a vertical strap from upper direction. It is a VII direction arrow line view of FIG. It is a side view which shows the state which cancelled | released temporary holding of FIG.

A furnace wall structure of a boiler apparatus according to an embodiment of the present invention will be described with reference to FIGS. 1 to 4.

As shown in FIG. 1, the furnace wall structure of this embodiment includes a vertical pipe wall (vertical water wall) 2 formed in the upper part of the boiler furnace 1 and a lower part of the vertical pipe wall 2 formed in the lower part of the boiler furnace 1. It is a combination water-wall structure provided with a spiral pipe wall (spiral water wall) 3 suspended continuously from the lower end. The boiler main body including the vertical pipe wall 2 and the spiral pipe wall 3 is suspended and installed on a ceiling girder in a structure (boiler building) composed of steel columns and beams (not shown).

The vertical pipe wall 2 and the spiral pipe wall 3 are membrane walls formed by welding and arranging water pipes (steel pipes, heat transfer pipes) 4 and 6 and fins (steel plates, membrane bars) 5 and 7 alternately. In the vertical pipe wall 2, the membrane wall is disposed at a vertical position along the boiler furnace 1 so that the water pipe 4 extends in the substantially vertical direction to form the boiler furnace 1. On the other hand, in the spiral pipe wall 3, the membrane wall is disposed at an inclined lateral position so that the water pipe 6 extends in the oblique direction to form the boiler furnace 1, and each water pipe 6 spirals around the boiler furnace 1. Roll around.

In the spiral pipe wall 3, the feed water in the water pipe 6 ascends while swirling around the boiler furnace 1, so the heat absorption amount does not differ depending on the position in the horizontal direction as in the vertical pipe wall 2. It is possible to perform uniform heating of the feed water with radiant heat from the Further, since the spiral tube wall 3 surrounds the boiler furnace 1 with a smaller number of water tubes 6 than the vertical tube wall 2, the flow velocity of the internal fluid can be increased and there is an advantage that there is little risk of nuclear boiling and film boiling. .

In the vicinity of each outer surface of the spiral pipe wall 3, a plurality of vertical straps (support members, U straps) 8 extending in a substantially vertical direction are arranged at substantially equal intervals in the horizontal direction. Each vertical strap 8 is a U-shaped cross section that opens toward the outside of the furnace, and the upper portion thereof is fixed to the vertical pipe wall 2 by welding and vertically descends. The spiral tube wall 3 is not fixed to the vertical strap 8, and the load of the spiral tube wall 3 is transferred to the vertical tube wall 2 by the spiral tube wall 3 itself without being transferred to the upper vertical tube wall 2 by the vertical strap 8. Ru.

Since the spiral pipe wall 3 is a membrane wall in which the water pipe 6 extending obliquely with respect to the direction of gravity and the fins 7 are welded and joined, the strength of the spiral pipe wall 3 itself is lower than that of the vertical pipe wall 2 Inevitably, since combustion is carried out in the furnace wall, it is necessary to take measures against deformation in the width direction due to the internal pressure of the furnace and measures against thermal expansion absorption in the height direction due to thermal expansion. For such measures, a backstay (a beam for supporting the furnace pressure inside the spiral pipe wall 3 etc.) 10 is arranged around the spiral pipe wall 3 so as to surround the outside of the spiral pipe wall 3 (See Figure 4). The backstay 10 is supported by a vertical strap 8, and the load of the backstay 10 is transmitted to the vertical pipe wall 2 via the vertical strap 8.

An example of the back stay 10 is shown in FIG. The back stay 10 shown in FIG. 4 includes a vertical back stay 11 disposed substantially parallel to the vertical strap 8 and extending substantially vertically, and a horizontal back stay 12 extending substantially horizontally, the vertical back stay 11 and the horizontal back stay 12. And are mutually connected crosswise. Vertical back stay 11 and horizontal back stay 12 are connected to vertical strap 8 by measure link (swing link) 13 and minor link (swing link) 14, and are connected to vertical strap 8 through measure link 13 and minor link 14. Be supported.

As shown in FIG. 1A, a plurality of panel side support fittings 20 are fixed to the outer surface of the spiral pipe wall 3. The plurality of panel support brackets 20 are provided at different positions with respect to each vertical strap 8.

As shown in FIGS. 2 and 3, the panel-side support fitting 20 is composed of a pair of left and right support plates 21 and a single presser pin 22, and the presser pins 22 are inserted through the left and right support plates 21. The pin insertion hole 23 is formed. The left and right support plates 21 are disposed on the left and right of the vertical strap 8 and welded to a base plate 24 welded to the outer surface of the spiral pipe wall 3. The presser pin 22 is disposed on the furnace outside of the vertical strap 8 with its both ends inserted through the pin insertion holes 23 of the left and right support plates 21 and is welded to one of the left and right support plates 21. The left and right support plates 21 and the presser pin 22 define a space 25 surrounding the vertical strap 8 between the outer surface of the spiral tube wall 3. The panel-side support fitting 20 functions as a support fitting capable of absorbing the lateral extension of the spiral pipe wall 3 and the longitudinal extension of the vertical strap 8 in the space 25.

Next, a new uncorroded furnace wall for replacing a part of the furnace wall part (the furnace wall part to be replaced) 30 due to the corrosion of a part of the spiral pipe wall 3 due to long-term use etc. The method of replacing the portion 31 will be described with reference to FIGS. 5 to 8.

The furnace wall portion 31 for replacement has the same shape and configuration as the furnace wall portion 30 to be replaced, and is manufactured at a factory or the like according to the furnace wall portion 30 to be replaced. Further, the upper edge (upper side) and the lower edge (lower side) of the outer peripheral edge of the furnace wall portion 30 to be replaced are set in the fins 7 along the inclination direction of the water pipe 6. The left and right side edges (left side and right side) are linearly continuous along the vertical direction between the left edge of the upper edge and the left edge of the lower edge and between the right edge of the upper edge and the right edge of the lower edge You may set, and you may set in step shape so that it may be substantially orthogonal to each axial direction (inclination direction) with respect to the several water pipe 6 located in a line up and down.

In FIG. 5, the furnace wall portion 31 for replacement and the furnace wall portion 30 to be replaced represent one large furnace wall portion, but in the following cutting process and mounting process, the furnace wall portion 31 for replacement And / or the furnace wall portion 30 to be replaced may be divided and divided into a plurality of left, right, upper and lower parts, and cutting and mounting may be sequentially performed. At this time, the number and size of the divisions / divisions are not particularly limited.

When replacing the furnace wall portion 30 to be replaced with the furnace wall portion 31 for replacement, first, the spiral pipe wall 3 below the furnace wall portion 30 to be replaced is fixed to the vertical strap 8 and temporarily held (provisionally Holding process). The vertical straps 8 temporarily holding the spiral tube wall 3 include vertical straps 8 passing on the outer surface of the furnace wall portion 30 to be replaced, and vertical straps 8 passing on the left and right outsides of the furnace wall portion 30 to be replaced. included.

Specifically, on the left and right sides of the vertical strap 8, a plurality of flat plate-like filler plates 32 are fixed by welding to the outer surface of the spiral pipe wall 3 (for example, the outer surface of the water pipe 6 and / or the outer surface of the fins 7) A flat support plate (first temporary holding member) 33 is fixed to the outer surface of the plate 32 by welding, and a prismatic prismatic support (second temporary holding member, support post) 34 is welded to the outer surface of the vertical strap 8 by welding. Fix and fix the support plate 33 to the prismatic support 34 by welding.

The plurality of filler plates 32 are adjusted and fixed such that the outer surfaces thereof are disposed on the same plane. The support plate 33 is, for example, a rectangular steel plate whose desired thickness and length are selected from the range of 15 mm to 50 mm and the length of one side of 150 mm to 400 mm. In addition, the prismatic support 34 is a prismatic steel material having a rectangular cross section (a square or a rectangle close to a square) whose desired length is selected from the range of 20 mm to 50 mm on one side. The total length in the longitudinal direction (vertical direction) of the prismatic support 34 is set to be substantially the same as the total length in the longitudinal direction (vertical direction) of the support plate 33 or slightly shorter than the total length of the support plate 33.

The filler plate 32 may be omitted, and the support plate 33 may be directly welded and fixed to the outer surface of the spiral pipe wall 3. Moreover, it is preferable to set the furnace wall portion 30 to be replaced so that the outer edge thereof does not pass through the panel side support fitting 20 (it passes through the area away from the panel side support fitting 20).

Next, the outer edge (outer peripheral edge) of the furnace wall portion 30 to be replaced is cut, and the furnace wall portion 30 to be replaced is suspended by a wire rope (not shown) and removed from the spiral pipe wall 3 (cutout process). By such removal, a wide range of openings 35 are formed in the spiral tube wall 3.

Next, the furnace wall portion 31 for replacement is lifted with a wire rope and joined to the peripheral portion of the opening 35 so as to close the opening 35 of the spiral pipe wall 3 formed by the removal of the furnace wall portion 30 to be replaced. (Mounting process). At this time, the end edges of the water pipe 6 are joined by welding so that the water pipe 6 remaining on the left and right of the opening 35 and the water pipe 6 of the furnace wall portion 31 for replacement communicate in a watertight manner.

Finally, temporary holding of the spiral tube wall 3 with respect to the vertical strap 8 is released (temporary holding release step).

Specifically, the welds 36 between the vertical strap 8 and the prismatic support 34 and the welds 37 between the support plate 33 and the prismatic support 34 are cut out with a sander or the like, and the vertical strap 8 and the support plate 33 By removing the support 34, the temporary holding of the spiral tube wall 3 is released as shown in FIG.

According to the present embodiment, when partially cutting out the furnace wall portion 30 to be replaced of a part of the spiral pipe wall 3 and replacing it with the furnace wall portion 31 for replacement, the furnace wall portion 30 to be replaced is Since the lower spiral pipe wall 3 of the furnace wall portion 30 to be replaced is fixed to the vertical strap 8 and temporarily held before cutting out, cutting out of the furnace wall portion 30 to be replaced widens a wide area on the spiral pipe wall 3 In the state in which the opening 35 is formed, the load of the spiral pipe wall 3 below the opening 35 is temporarily deposited on the vertical strap 8 and transmitted to the vertical pipe wall 2 via the vertical strap 8. Therefore, stress concentration on both sides of the opening 35 is alleviated, and deformation and damage of the spiral pipe wall 3 can be prevented.

Also, after joining the replacement wall portion 31 to the peripheral edge of the opening 35 so as to close the opening 35 of the spiral tube wall 3, the temporary holding of the spiral tube wall 3 with respect to the vertical strap 8 is released. Unnecessary interference between the spiral pipe wall 3 and the vertical strap 8 at the time of operation can be prevented, and even after the furnace wall portion 30 is replaced, the vertical strap 8 can be functioned in the same manner as before replacement.

Further, the support plate 33 fixed to the spiral pipe wall 3 is welded and fixed to the prismatic support 34 fixed to the vertical strap 8 by welding, and in the temporary holding release step, the vertical strap 8 and the prismatic support 34 The temporary holding of the spiral tube wall 3 is released by cutting the welds 36 between the two and the welds 37 between the support plate 33 and the prismatic support 34 and removing the prismatic supports 34 from the vertical straps 8 and the support plate 33 Therefore, temporary holding of the spiral pipe wall 3 can be released by a simple operation.

Further, since the support plate 33 is left on the spiral pipe wall 3 side, damage to the spiral pipe wall 3 due to release of temporary holding can be reliably prevented. Furthermore, since the prismatic column support 34 is removed, unnecessary interference between the spiral pipe wall 3 and the vertical strap 8 can be reliably prevented during operation of the boiler apparatus.

The present invention is not limited to the above-described embodiment described above as an example and the examples thereof, and even if it is other than the above-described embodiment and the like, it does not deviate from the technical concept of the present invention. If it is, various changes are possible according to design etc.

1: Boiler furnace 2: Vertical pipe wall (vertical water wall)
3: Spiral tube wall (spiral water wall)
4, 6: Water pipe (steel pipe, heat transfer pipe)
5,7: Fins (Steel plate, membrane bar)
8: Vertical strap (support member, U strap)
10: back stay 11: vertical back stay 12: horizontal back stay 20: panel side support bracket 21: support plate 22: press pin 23: pin insertion hole 24: base plate 25: space 30: partial furnace wall portion (replacement target Of the furnace wall)
31: furnace wall portion 32 for replacement: filler plate 33: support plate (first temporary holding member)
34: Square column support (second temporary holding member, support post)
35: Opening 36: Weld 37 between vertical strap and prismatic support 37: Weld between support plate and prismatic support

Claims

A boiler furnace wall having an upper vertical pipe wall and a lower spiral pipe wall suspended from the vertical pipe wall, a back stay disposed around the spiral pipe wall to support furnace pressure, and the vertical pipe wall And a supporting member fixed to the support member for supporting the back stay, the supporting member hanging near the outer surface of the spiral pipe wall without being fixed to the spiral pipe wall, one of the spiral pipe walls A boiler furnace wall replacement method in which the furnace wall portion of the section is replaced with a furnace wall portion for replacement,
A temporary holding step of fixing and temporarily holding the spiral pipe wall below the partial furnace wall portion with respect to the support member;
After the temporary holding step, cutting out the outer edge of the portion of the furnace wall portion to extract the portion of the furnace wall portion from the spiral pipe wall;
And a mounting step of joining the replacement furnace wall portion to the peripheral edge portion of the opening so as to close the opening of the spiral pipe wall formed by the cutout step. Construction method.
The boiler furnace wall replacement method according to claim 1, wherein
The boiler furnace wall replacement method according to claim 1, further comprising: a temporary holding releasing step for releasing temporary holding of the spiral pipe wall with respect to the support member after the attaching step.
The boiler furnace wall replacement method according to claim 2, wherein
In the temporary holding step, the first temporary holding member is fixed to the spiral pipe wall, and the second temporary holding member is welded and fixed to the support member, and the first temporary holding member is fixed to the second temporary holding member. Temporarily holding the spiral pipe wall by welding and fixing the holding member;
In the temporary holding releasing step, a weld between the support member and the second temporary holding member and a weld between the first temporary holding member and the second temporary holding member are cut off, and the support member is removed. And removing the temporary holding of the spiral pipe wall by removing the second temporary holding member from the first temporary holding member.
A boiler furnace wall having an upper vertical pipe wall and a lower spiral pipe wall suspended from the vertical pipe wall, a back stay disposed around the spiral pipe wall to support furnace pressure, and the vertical pipe wall And a supporting member fixed to the support member for supporting the back stay, the supporting member hanging near the outer surface of the spiral pipe wall without being fixed to the spiral pipe wall, one of the spiral pipe walls A temporary holding structure of a boiler furnace wall in which the spiral pipe wall is temporarily held by the support member when replacing the furnace wall portion of the section with a furnace wall portion for replacement.
A first temporary holding member fixed to the spiral pipe wall;
And a second temporary holding member fixed to the support member by welding.
The temporary holding structure for a boiler furnace wall, wherein the first temporary holding member is fixed to the second temporary holding member by welding.