JP6335380B1 - Furnace wall repair method - Google Patents

Abstract

An object of the present invention is to reduce the residual stress of a repair pipe attached by welding to a furnace wall of a gasifier or a boiler. A furnace wall repair method according to at least one embodiment of the present invention is a furnace wall repair method constituted by a plurality of pipes, the step of selecting a repair target portion in the plurality of pipes; Cutting a predetermined section of the pipe including the repair target portion, and attaching both ends of a repair pipe having a curved portion to the furnace wall from which the predetermined section has been cut by welding. [Selection] Figure 2

Description

  The present disclosure relates to a method for repairing a furnace wall.

  In gasifiers that partially burn and gasify carbon-containing solid fuels such as boilers and coal, in order to suppress heating of the furnace wall, the furnace wall includes a plurality of pipes through which a cooling medium passes and each pipe. It has a plurality of fins provided therebetween, and the pipe and the fin are joined to each other by welding or the like (see Patent Document 1).

JP 2010-254727 A

  The piping that constitutes the furnace wall may be damaged, such as thinning or cracking, due to the passage of operating time of a gasifier or a boiler. In such a case, instead of renewing the entire pipe where the thinning or cracking has occurred, the predetermined section including the thinning or cracking is excised, and the repair pipe is attached to the furnace wall from which the predetermined section has been excised. Repair may be performed by welding.

However, the inventors have noticed that when a repair pipe is attached to a furnace wall with a predetermined section removed by welding, the life of the repair pipe may be shorter than originally predicted.
As a result of intensive studies, the inventors of the present invention have found that when a repair pipe is attached to a furnace wall with a predetermined section removed by welding, a tensile stress occurs in the repair pipe due to shrinkage of the weld due to a decrease in temperature after welding. It has been found that the life of the repair pipe may be shortened if the gasifier or the boiler is operated in a state where the tensile stress generated as described above remains as a residual stress.

  In view of the above circumstances, at least one embodiment of the present invention aims to reduce the residual stress of a repair pipe attached to a furnace wall by welding.

(1) A method for repairing a furnace wall according to at least one embodiment of the present invention includes:
A method for repairing a furnace wall composed of a plurality of pipes,
Selecting a repair target location in the plurality of pipes;
Cutting out a predetermined section of the pipe including the repair target portion;
Attaching both ends of a repair pipe having a curved portion to the furnace wall from which the predetermined section has been cut by welding;
Is provided.

  According to the method of (1) above, both ends of the repair pipe having a curved portion are attached by welding to the furnace wall from which a predetermined section has been cut. Therefore, when the temperature of the welded portion at both ends decreases after the repair pipe is attached and the welded portion contracts, the curved portion is pulled from both ends. Thereby, it deform | transforms so that the bending of a music part may be extended. Thus, the residual stress which arises in a repair pipe | tube can be reduced by deform | transforming so that a curved part may be extended.

(2) In some embodiments, in the method of (1), the predetermined section is a straight pipe portion in the plurality of pipes.

  According to the method (2), the straight pipe portion is excised as a predetermined section from the pipe including the repair target portion. And as shown in said (1), the both ends of the repair pipe which has a curved part are attached to the furnace wall by which this predetermined area was excised by welding. Therefore, even if the temperature of the welded portion at both ends decreases after the repair tube is attached and the welded portion contracts, the residual stress generated in the repaired tube can be reduced by deforming so that the bending of the curved portion is extended.

(3) In some embodiments, in the method of (1) or (2) above,
The repair pipe is
One end side bend formed on one end side of the repair pipe,
Including a first repair pipe having the other end side bent portion formed on the other end side of the repair pipe, and an intermediate portion formed between the one end side bent portion and the other end side bent portion,
In the step of attaching both ends of the repair pipe by welding, the first repair pipe is attached to the furnace wall from which the predetermined section has been cut so that the intermediate portion protrudes toward the outside of the furnace.

  According to the method of (3) above, the first repair pipe having the one end side bend and the other end bend is attached to the furnace wall from which a predetermined section has been cut. Even if the temperature is lowered and the welded portion contracts, the residual stress generated in the first repair pipe can be reduced by deforming so that the bending of the one end side bent portion and the other end side bent portion is extended. Also, according to the method (3), the first repair pipe is attached to the furnace wall whose predetermined section has been cut so that the intermediate portion protrudes toward the outside of the furnace, so that the intermediate portion has an influence on the temperature of the furnace. It becomes difficult to receive. Further, according to the method (3), the first repair pipe is attached to the furnace wall whose predetermined section is cut so that the intermediate portion protrudes toward the outside of the furnace. Even so, the other pipe adjacent to the cut out predetermined section does not interfere with the first repair pipe having the one end side curved portion and the other end side curved portion.

(4) In some embodiments, in the method of (1) above,
In the step of selecting the repair target location, a location where the degree of wear in the pipe is greater than or equal to a specified wear level is selected as the repair target location,
In the step of cutting out the predetermined section of the pipe, if the pipe including the repair target portion is a pipe including a curved pipe part, even if the degree of wear of the curved pipe part is less than the specified wear degree A section including at least a part of the curved pipe portion is set as the predetermined section, and the predetermined section is excised.

  According to the method of (4) above, by including at least a part of the curved pipe portion in the predetermined section to be excised, the curved portion corresponding to the portion included in the predetermined section of the curved pipe portion is used as a repair pipe. Can be provided. As a result, even if the temperature of the welded part at both ends drops after the repair pipe is attached and the welded part shrinks, the bending of the curved part is deformed to be extended, thereby reducing the residual stress generated in the repaired pipe. it can.

(5) In some embodiments, in any of the above methods (1) to (4),
In order to reduce the tensile stress generated in the repair pipe due to the shrinkage after the welding at both ends of the repair pipe after the repair pipe is attached to the furnace wall where the predetermined section is cut by welding, The method further includes the step of implementing a stress relaxation measure for performing at least one of cooling and heating the furnace wall from which the predetermined section is cut.

  According to the above method (5), since the stress relaxation measure described later is further implemented, the residual stress generated in the repair pipe can be further reduced.

(6) A method for repairing a furnace wall according to at least one embodiment of the present invention includes:
A method for repairing a furnace wall composed of a plurality of pipes,
Selecting a repair target location in the plurality of pipes;
Cutting out a predetermined section of the pipe including the repair target portion;
Attaching both ends of the repair pipe to the furnace wall from which the predetermined section has been removed by welding;
At least one of cooling of the repair pipe and heating of the furnace wall from which the predetermined section has been cut in order to reduce tensile stress generated in the repair pipe due to shrinkage after welding at both ends of the repair pipe Implementing stress relief measures to do one of the following;
Is provided.

  According to the above method (6), since the stress relaxation measures described later are implemented, the residual stress generated in the repair pipe can be reduced.

(7) In some embodiments, in the method of (6) above,
In the step of implementing the stress relaxation measure, the repair pipe is cooled,
In the step of attaching both ends of the repair pipe by welding, the repair pipe that has been cooled in the step of implementing the stress relaxation measure is attached by welding.

  According to the above method (7), the repaired pipe in a cooled state is attached by welding, so that the repair pipe is thermally stretched when the temperature of the repaired pipe that has been cooled after the attachment rises. Thereby, since the shrinkage | contraction after welding in the both ends of a repair pipe | tube can be reduced, the residual stress which arises in a repair pipe | tube can be reduced.

(8) In some embodiments, in the method of (6) above,
The furnace wall includes fins connecting adjacent pipes,
In the step of implementing the stress relaxation measure, a predetermined range of the furnace wall including an adjacent pipe adjacent to the pipe including the repair target portion is heated,
In the step of attaching both ends of the repair pipe by welding, the repair pipe is welded to the furnace wall from which the predetermined section is cut in a state where the predetermined range of the furnace wall is heated in the step of implementing the stress relaxation measure. Attach with.

  According to the above method (8), since adjacent pipes are connected by fins, the adjacent pipes are heated by heating a predetermined range of the furnace wall including the adjacent pipes adjacent to the pipe including the repair target part. When extended, the distance between the ends of the pipes remaining on the furnace wall from which the predetermined section has been cut becomes longer. In this state, after attaching both ends of the repair pipe by welding, when the temperature of the predetermined range that was heated decreases, the adjacent pipe contracts, so the end of the pipe remaining on the furnace wall where the predetermined section was cut The distance between them becomes shorter. Thereby, since the shrinkage | contraction after welding in the both ends of a repair pipe | tube can be reduced, the residual stress which arises in a repair pipe | tube can be reduced.

(9) In some embodiments, in the method of (6), in the step of implementing the stress relaxation measure, the repair pipe is attached to the furnace wall from which the predetermined section is cut by welding. The repair pipe is cooled, and the repair pipe is yielded by applying a tensile force by thermal stress.

  According to the method (9) above, the repair pipe after welding is cooled, and the repair pipe is yielded by applying a tensile force due to thermal stress. Therefore, when the temperature of the repair pipe returns to room temperature, the repair pipe The residual stress of the repair pipe is lower than before yielding. Thereby, the residual stress which arises in a repair pipe can be reduced.

(10) In some embodiments, in the method of (6) above, in the step of implementing the stress relaxation measure, after the repair pipe is attached to the furnace wall from which the predetermined section is cut by welding, A predetermined range of the furnace wall including the adjacent pipe adjacent to the pipe including the repair target portion is heated, and a tensile force is applied to the repair pipe to yield the repair pipe.

  According to the method of (10) above, after attaching the repair pipe by welding, the adjacent pipe adjacent to the pipe including the repair target portion, that is, the predetermined range of the furnace wall including the adjacent pipe adjacent to the repair pipe is heated, Since the repair pipe is yielded by applying a tensile force to the repair pipe by the thermal elongation of the predetermined range, when the temperature of the predetermined range returns to room temperature, the residual stress of the repair pipe is lower than before the yield of the repair pipe To do. Thereby, the residual stress which arises in a repair pipe can be reduced.

  According to at least one embodiment of the present invention, the residual stress of the repair pipe attached to the furnace wall by welding can be reduced.

It is a figure which shows typically a part of furnace wall in gasification apparatuses, such as a coal gasification furnace, and a boiler to which the repair method of the furnace wall concerning some embodiments is applied, (a) It is the figure seen from the furnace inner side, (b) is B1-B1 arrow sectional drawing of (a). It is a flowchart which shows the general | schematic flow in the repair method of the furnace wall which concerns on some embodiment. It is a figure which shows typically a part of furnace wall after excising a cutting section from repair object piping, (a) is the figure which looked at the furnace wall from the furnace inner side, (b) is B3 of (a). -B3 arrow sectional drawing. It is a figure which shows a part of furnace wall after attaching a repair pipe, (a) is the figure which looked at the furnace wall from the furnace inner side, (b) is B4-B4 arrow view of (a) It is sectional drawing. It is the figure which shows a part of the furnace wall after connecting a repair pipe and piping of the both sides of a repair pipe with a seal plate, (a) is the figure which looked at the furnace wall from the furnace inside, b) is a B5-B5 arrow sectional view of (a), and (c) is a C5-C5 arrow sectional view of (a). It is a typical figure when a part of furnace wall which has an opening part is seen from the furnace inner side. It is a flowchart which shows the general flow in the repair method of the furnace wall which concerns on other embodiment. It is a schematic diagram for demonstrating the thermal contraction of a repair pipe. It is a figure explaining a heating range. It is a figure which shows a mode that a repair pipe | tube is cooled. Schematic flow when applying stress relaxation measures implemented in step S20 in another embodiment of the furnace wall repair method to the furnace wall repair method according to some embodiments shown in FIGS. It is a flowchart which shows.

Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described in the embodiments or shown in the drawings are not intended to limit the scope of the present invention, but are merely illustrative examples. Absent.
For example, expressions expressing relative or absolute arrangements such as “in a certain direction”, “along a certain direction”, “parallel”, “orthogonal”, “center”, “concentric” or “coaxial” are strictly In addition to such an arrangement, it is also possible to represent a state of relative displacement with an angle or a distance such that tolerance or the same function can be obtained.
For example, an expression indicating that things such as “identical”, “equal”, and “homogeneous” are in an equal state not only represents an exactly equal state, but also has a tolerance or a difference that can provide the same function. It also represents the existing state.
For example, expressions representing shapes such as quadrangular shapes and cylindrical shapes represent not only geometrically strict shapes such as quadrangular shapes and cylindrical shapes, but also irregularities and chamfers as long as the same effects can be obtained. A shape including a part or the like is also expressed.
On the other hand, the expressions “comprising”, “comprising”, “comprising”, “including”, or “having” one constituent element are not exclusive expressions for excluding the existence of the other constituent elements.

FIG. 1 is a diagram schematically showing a part of a furnace wall in a gasifier such as a coal gasifier or a boiler to which a method for repairing a furnace wall according to some embodiments is applied. a) is a view of the furnace wall viewed from the inside of the furnace, and FIG. 1B is a cross-sectional view taken along arrow B1-B1 in FIG.
The furnace wall 10 includes a plurality of pipes 11 through which coolant such as water supply or steam as cooling water flows, and fins 12 that connect adjacent pipes 11 to each other.

  The piping 11 constituting the furnace wall 10 may be damaged such as thinning or cracking with the passage of operation time of a gasifier or a boiler. In such a case, instead of renewing the entire pipe 11 in which the thinning or cracking has occurred, the predetermined section including the thinning or cracking is excised as described below, and the predetermined section is cut off. Repair may be performed in which a repair pipe is welded to the furnace wall 10 that has been welded.

FIG. 2 is a flowchart showing a schematic flow in a method for repairing a furnace wall according to some embodiments. The furnace wall repair method according to some embodiments includes a step S1 for selecting a repair target portion in the plurality of pipes 11, a step S3 for cutting a predetermined section of the pipe 11 including the repair target portions, and a predetermined section being cut. Step S5 which attaches the both ends of the repair pipe which has a curved part to welding furnace wall 10 made by welding.
That is, according to the furnace wall repair method according to some embodiments, both ends of a repair pipe having a curved portion are attached to the furnace wall 10 from which a predetermined section is cut by welding. Therefore, when the temperature of the welded portion at both ends decreases after the repair pipe is attached and the welded portion contracts, the curved portion is pulled from both ends. Thereby, it deform | transforms so that the bending of a music part may be extended. Thus, the residual stress which arises in a repair pipe | tube can be reduced by deform | transforming so that a curved part may be extended. Details will be described below.

  In the following description, step S1 for selecting a repair target portion in a plurality of pipes 11 is also called step S1 for selecting a repair target portion, and a predetermined section of the pipe 11 including the repair target portion is excised. This is also called step S3 for excising a predetermined section, and step S5 for attaching both ends of a repair pipe having a curved portion to the furnace wall 10 from which the predetermined section has been excised is attached to both ends of the repair pipe by welding. Also referred to as step S5.

In step S1 of selecting a repair target location, a repair target location is selected based on, for example, an inspection result such as a flaw detection test performed in advance. For example, by ultrasonic inspection or the like, a portion where the degree of wear in the pipe 11 is equal to or higher than a specified wear degree, for example, a place where the pipe 11 is thinned or cracked to the extent that repair is determined to be necessary, is to be repaired. Select as the location. For convenience of explanation, in the following explanation, the pipe 11 in which the repair target portion exists among the plurality of pipes 11 is referred to as a repair target pipe 13.
For example, in FIG. 1A showing a part of the furnace wall 10, it is assumed that the repair target portion 14 exists in the central pipe 11 among the five pipes 11 arranged in parallel. That is, in FIG. 1A, the central pipe 11 among the five pipes 11 is the repair target pipe 13.

In step S3 for excising the predetermined section, first, the predetermined section including the repair target portion 14 in the repair target pipe 13 is set as a section to be excised. A predetermined section including the repair target portion 14 is also referred to as an excision section 15.
For example, in the embodiment shown in FIGS. 1 and 3, the predetermined section including the repair target portion 14 is a straight pipe portion in the pipe 11.

And in step S3 which excises a predetermined area, as shown in FIG. 3, the excision area 15 is excised from the piping 13 for repair. FIG. 3 is a diagram schematically showing a part of the furnace wall 10 after the excision section 15 has been excised from the pipe 13 to be repaired, and FIG. 3A is a diagram of the furnace wall 10 viewed from the inside of the furnace. FIG. 3B is a cross-sectional view taken along arrow B3-B3 in FIG.
In step S3 for cutting a predetermined section, the fins 12 around the cutting section 15 are also cut.

  In step S5 where both ends are attached by welding, as shown in FIG. 4, the repair pipe 20 is attached to the furnace wall 10 from which a predetermined section has been cut. FIG. 4 is a view schematically showing a part of the furnace wall 10 after the repair pipe 20 is attached, and FIG. 4A is a view of the furnace wall 10 as seen from the inside of the furnace. b) is a B4-B4 arrow sectional view of FIG.

The repair pipe 20 has a bent pipe portion 24 including a plurality of bent portions 22 and a straight portion 23 between both end portions 21. In the following description, a section that is curved in the pipe is referred to as a curved section, and a section that extends linearly in the pipe is referred to as a straight section. Further, a section including at least one curved portion is referred to as a curved pipe portion, and the curved pipe portion may include at least one straight portion. For example, the repair pipe 20 shown in FIG. 4B is a curved pipe portion including a plurality of curved portions and a plurality of straight portions. That is, in the repair pipe 20 shown in FIG. 4B, the first straight part 23a having one end of the upper end part 21a in FIG. 4B among the both end parts 21 and the other end of the first straight part 23a. One end is connected to the other end of the first straight portion 22a, the second straight portion 23b having one end connected to the other end of the first curved portion 22a, and the other end of the second straight portion 23b. And a third straight portion 23c having one end connected to the other end of the second curved portion 22b. 4B, one end is connected to the other end of the third curved portion 22c, and the third curved portion 22c has one end connected to the other end of the third straight portion 23c. The fourth straight portion 23d, one end connected to the other end of the fourth straight portion 23d, and one end connected to the other end of the fourth curved portion 22d. A fifth straight part 23e having the lower end part 21b in FIG. 4B as the other end is included.
Moreover, the section which consists of a straight part in piping is called a straight pipe part. The straight pipe portion does not include a curved portion.
In the following description, when any one of the first music part 22a to the fourth music part 22d is not specified, the description of the alphabet at the end of the code is omitted, and is simply referred to as the music part 22. Similarly, in the case where any one of the first straight part 23a to the fifth straight part 23e is not specified, the description of the alphabet at the end of the code is omitted, and is simply referred to as the straight part 23.

Therefore, in the embodiment shown in FIG. 4, the upper end portion 13 a of the repair target pipe 13 left on the furnace wall 10 and the upper end portion 21 a of the repair pipe 20 are left in step S <b> 5 where both ends of the repair pipe are attached by welding. Are connected by welding, and the lower end 13b of the repair target pipe 13 left on the furnace wall 10 and the lower end 21b of the repair pipe 20 are connected by welding.
That is, in the embodiment shown in FIGS. 1, 3, and 4, a straight pipe portion is cut out as a cut section 15 as a predetermined section from the repair target pipe 13 including the repair target portion 14. And the both ends 21 of the repair pipe | tube 20 which has a curved part are attached to the furnace wall 10 by which this predetermined area was excised by welding. Therefore, after the repair pipe 20 is attached, the welded portions at both ends 21, more specifically, the welded portion 5 a between the upper end portion 13 a of the repair target pipe 13 and the upper end portion 21 a of the repair pipe 20, and repair Even if the temperature of the welded portion 5b between the lower end portion 13b of the target pipe 13 and the lower end portion 21b of the repair pipe 20 decreases and the welded portion contracts, the bending of the bent portion 22 is extended. By deforming, the residual stress generated in the repair pipe 20 can be reduced.

In one embodiment shown in FIG. 4, the repair pipe 20 includes one end side bent portion 25 a formed on one end side of the repair pipe 20, and the other end side bent portion 25 b formed on the other end side of the repair pipe 20. And it has the intermediate part 26 formed between the one end side curved part 25a and the other end side curved part 25b. The repair pipe 20 shown in FIG. 4 is also referred to as a first repair pipe 20A. The one end side bent portion 25a of the first repair pipe 20A is, for example, the first bent portion 22a, and the other end side bent portion 25b is, for example, the fourth bent portion 22d. The intermediate portion 26 of the first repair pipe 20A includes, for example, a second straight portion 23b, a second curved portion 22b, a third straight portion 23c, a third curved portion 22c, and a fourth straight portion 23d. It is.
In the embodiment shown in FIG. 4, in step S <b> 5 in which both ends of the repair pipe are attached by welding, the first repair pipe 20 </ b> A is attached to the furnace wall 10 whose predetermined section is cut so that the intermediate portion 26 protrudes toward the outside of the furnace. Install.

Thus, since the 1st repair pipe 20A which has the one end side curved part 25a and the other end side curved part 25b is attached to the furnace wall 10 by which the predetermined area was excised, after welding of the 1st repair pipe 20A, the welding part 5a, Even when the temperature of 5b decreases and the welded portions 5a and 5b contract, the first curved portion 22 including the one end side bent portion 25a and the other end side bent portion 25b are deformed so that the bend is extended. Residual stress generated in the repair pipe 20A can be reduced.
In the embodiment shown in FIG. 4, the first repair pipe 20A is attached to the furnace wall 10 whose predetermined section is cut so that the intermediate part 26 protrudes toward the outside of the furnace. It becomes difficult to be affected. Further, in the embodiment shown in FIG. 4, the first repair pipe 20A is attached to the furnace wall 10 whose predetermined section is cut so that the intermediate portion 26 protrudes toward the outside of the furnace. Even if it is a part, it has the other piping 11 adjacent to the cut-out predetermined section, the 1st repair pipe 20A which has the one end side curved part 25a and the other end side curved part 25b, and the intermediate part 26 protrudes from Does not interfere.

In addition, in step S5 which attaches the both ends of a repair pipe | tube with welding, after the repair pipe | tube 20 is attached, the excised fin 12 is restored. Specifically, for example, as shown in FIG. 5, the repair pipe 20 and the pipe 11 adjacent to the repair pipe 20 are connected by a seal plate 16. Thereby, airtightness inside a furnace is maintained. 5 is a diagram schematically showing a part of the furnace wall 10 after the repair pipe 20 and the pipe 11 adjacent to the repair pipe 20 are connected by the seal plate 16, and FIG. FIG. 5 (b) is a cross-sectional view taken along the line B5-B5 in FIG. 5 (a), and FIG. 5 (c) is a view of C5 in FIG. 5 (a). -C5 arrow sectional drawing.
The furnace inner surface of the seal plate 16 and the outer surface of the repair pipe 20 inside the furnace may be covered with a refractory material.

Further, for example, as shown in FIG. 6, when the repair target pipe 13 has a curved pipe portion due to the provision of an opening 17 for arranging a burner or the like (not shown) on the furnace wall 10, a predetermined section is cut off. In step S3, even when the degree of wear of the bent pipe portion is less than a predetermined wear degree, a section including at least a part of the bent pipe portion is set as the cut section 15, and the cut section 15 is cut off. To do.
FIG. 6 is a schematic view when a part of the furnace wall 10 having the opening 17 for arranging a burner or the like (not shown) is viewed from the inside of the furnace.

For example, as shown in FIG. 6, when the repair target portion 14 is present in the straight pipe portion 11 d of the pipe 11 having the curved pipe portion 11 c, the wear degree of the bent pipe portion 11 c is less than a specified wear degree. Also, a section including at least a part of the curved pipe portion 11c is set as the cutting section 15. In the example shown in FIG. 6, the repair target location 14 exists in the straight pipe portion 11d below the curved pipe portion 11c. The lower end 15 b of the excision section 15 is set below the repair target location 14. An upper end 15a of the excision section 15 in the drawing is set above the repair target portion 14 and includes at least one bent portion 22 of the bent tube portion 11c.
By setting the excision section 15 in this way, by including at least a part of the curved pipe portion 11c in the excision section 15, a curved portion corresponding to the curved portion 22 included in the excised section 15 in the curved pipe portion 11c. The repair pipe 20 can be provided. As a result, even if the temperature of the welded portion 5a at both ends 21 (see FIG. 5) drops and the welded portion 5a contracts after the repair pipe 20 is attached, the bent portion of the bent portion is deformed to be extended. The residual stress generated in the repair pipe 20 can be reduced.
If the shape of the repair pipe 20 is the same as that of the excision section 15, the repair pipe 20 can be prevented from interfering with the pipe 11 adjacent to the repair pipe 20.

(About other embodiment of the repair method of a furnace wall)
Another embodiment of the furnace wall repair method will be described.
FIG. 7 is a flowchart showing a schematic flow in a furnace wall repair method according to another embodiment. In the furnace wall repair method according to another embodiment, a step S1 for selecting a repair target portion in the plurality of pipes 11, a step S3 for cutting a predetermined section of the pipe 11 including the repair target portion, and a predetermined section are cut off. Step S11 for attaching both ends of the repair pipe to the furnace wall 10 by welding, and cooling of the repair pipe and a predetermined section to reduce tensile stress generated in the repair pipe due to shrinkage after welding at both ends of the repair pipe. Step S20 for implementing a stress relaxation measure for performing at least one of heating of the cut furnace wall 10.
In another embodiment of the method for repairing a furnace wall, it is assumed that the excision section 15 is a straight pipe portion and the repair pipe 20 does not have a curved portion 22.

  In the furnace wall repairing method according to another embodiment, the step S1 for selecting a repair target portion in the plurality of pipes 11 shown in FIG. 7 and the step S3 for excising a predetermined section of the pipe 11 including the repair target portions are as follows: 2 is the same as step S1 for selecting a repair target portion in the plurality of pipes 11 shown in FIG. 2 and step S3 for cutting out a predetermined section of the pipe 11 including the repair target portion.

In the following description, step S11 in which both ends of the repair pipe are attached to the furnace wall 10 from which a predetermined section has been removed by welding is also referred to as step S11 in which both ends of the repair pipe are attached by welding. Further, in the following description, in order to reduce the tensile stress generated in the repair pipe due to shrinkage after welding at both ends of the repair pipe, at least cooling of the repair pipe and heating of the furnace wall 10 from which a predetermined section is cut off are performed. Step S20 for implementing either one of the stress relaxation measures is also referred to as step S20 for implementing stress relaxation measures, or simply as step S20.
For convenience of illustration, in the flowchart of FIG. 7, it is described as if step S <b> 20 for performing stress relaxation measures is performed after step S <b> 11 for attaching both ends of the repair pipe by welding, as described later. In addition, step S20 for performing stress relaxation measures may be performed before step S11 for attaching both ends of the repair pipe by welding, and stress relaxation measures may be performed in parallel with the execution of step S11 for attaching both ends of the repair pipe by welding. You may implement step S20 which implements.

  In the method for repairing a furnace wall according to another embodiment, a stress relaxation measure described later is performed, so that residual stress generated in the repair pipe 20 can be reduced.

(About the stress relaxation measure implemented by step S20 of one Embodiment)
Hereinafter, the stress relaxation measure implemented by step S20 which implements a stress relaxation measure is demonstrated.
The stress relaxation measure implemented in step S <b> 20 of one embodiment is to cool the repair pipe 20 before being attached to the furnace wall 10. For example, as shown in FIG. 8, when the repair pipe 20 before being attached to the furnace wall 10 is cooled, the entire length of the repair pipe 20 is shortened. FIG. 8 is a schematic diagram for explaining the thermal contraction of the repair pipe 20, the broken line shows the state of the repair pipe 20 before cooling, and the solid line shows the state of the repair pipe 20 after cooling. .
Considering the shrinkage of the welded parts 5a and 5b after welding, the length of the repair pipe 20 is previously increased by a predetermined length. And in step S20, this repair pipe | tube 20 is heat-shrinked by cooling before the attachment to the furnace wall 10. FIG.
When the linear expansion coefficient is α, the length of the repair pipe 20 before cooling is L1, and the temperature difference before and after cooling is ΔT1, the heat shrinkage amount ΔL1 of the repair pipe 20 is expressed by the following equation (1). The
ΔL1 = L1 × α × ΔT1 (1)
For example, if the linear expansion coefficient is α = 1.33 × 10 ⁻⁵ (1 / K) and the heat shrinkage ΔL1 is 0.1% of the length L1 of the repair pipe, the temperature difference ΔT1 before and after cooling. Is 75 (K).

And in step S11 which attaches the both ends of a repair pipe by welding, the repair pipe 20 in the state cooled by step S20 which implements a stress relaxation measure is attached by welding.
Thus, since the repair pipe 20 in the cooled state is attached by welding, when the temperature of the repair pipe 20 cooled after the attachment rises, the repair pipe 20 is thermally expanded. Thereby, since the shrinkage | contraction after welding in the both ends 21 of the repair pipe | tube 20 can be reduced, the residual stress which arises in the repair pipe | tube 20 can be reduced.
In step S11 where both ends of the repair pipe are attached by welding, the cut fins 12 are repaired after the repair pipe 20 is attached. The same applies to step S11 where both ends of the repair pipe described below are attached by welding.

(Regarding stress relaxation measures implemented in step S20 of other embodiments)
Moreover, the stress relaxation measure implemented by step S20 of other embodiment heats the predetermined range of the furnace wall 10 containing 11 A of adjacent piping which is the piping 11 adjacent to the repair object piping 13 containing the repair object location 14. FIG. It is. In step S20 of another embodiment, for example, as shown in FIG. 9, a predetermined range of the furnace wall 10 including the adjacent pipe 11A is heated. The predetermined range is also called a heating range 18. FIG. 9 is a diagram illustrating the heating range 18. The heating range 18 will be described later.

As described above, since the adjacent pipes 11 are connected to each other by the fins 12, when the heating range 18 is thermally expanded by heating the heating range 18, the upper side of the pipe 13 to be repaired left on the furnace wall 10. The distance between the end portion 13a and the lower end portion 13b is increased.
The thermal expansion amount ΔL2 of the heating range 18 is α, where the linear expansion coefficient is α, the length of the heating range 18 along the extending direction of the pipe 11 is L2, and the temperature difference before and after heating is ΔT2. It is represented by the following formula (2).
ΔL2 = L2 × α × ΔT2 (2)
For example, the linear expansion coefficient is α = 1.33 × 10 ⁻⁵ (1 / K), and the thermal elongation amount ΔL2 is 0.1% of the length L2 of the heating range 18 along the extending direction of the pipe 11. Then, the temperature difference ΔT before and after heating is 75 (K).

The range along the extending direction of the pipe 11 in the heating range 18 is, for example, the position in the vertical direction in FIG. 9, and the lower end 13b from the same position as the upper end 13a of the pipe 13 to be repaired. And the same range. In this case, the length L2 of the heating range 18 along the extending direction of the pipe 11 is equal to the distance between the upper end 13a and the lower end 13b of the pipe 13 to be repaired.
In addition, since adjacent piping 11 is connected by the fin 12, if heat is applied to a part of the heating range 18, the periphery will also be heated by heat transfer. For example, even if the adjacent pipe 11A is not directly heated, the heat is transmitted to the adjacent pipe 11A through the fins 12 by heating the pipe 11 adjacent to the adjacent pipe 11A.

  Considering the shrinkage of the welded parts 5a and 5b after welding, the length of the repair pipe 20 is previously increased by a predetermined length. And in the state which heated the heating range 18, step S11 which attaches the both ends of a repair pipe by welding is implemented, and the both ends 21 of the repair pipe 20 are attached by welding. After that, when the heating of the heating range 18 is stopped and the temperature of the heating range 18 decreases, the heating range 18 contracts, so the distance between the upper end 13a and the lower end 13b of the repair target pipe 13 is also short. Become. Thereby, since the shrinkage | contraction after welding in the both ends 21 of the repair pipe | tube 20 can be reduced, the residual stress which arises in the repair pipe | tube 20 can be reduced.

(About the stress relaxation measure implemented by step S20 of other embodiment)
In addition, the stress relaxation measure implemented in step S20 of still another embodiment is to cool the repair pipe 20 after being welded to the furnace wall 10 from which a predetermined section has been cut, and to give a tensile force due to thermal stress. This is to yield the repair pipe 20.
After performing step S11 of attaching both ends of the repair pipe by welding and attaching both ends 21 of the repair pipe 20 by welding, the repair pipe 20 is cooled, for example, as shown in FIG. FIG. 10 is a diagram schematically illustrating the cooling of the cooling region 31 including the repair pipe 20. The cooling area 31 is an area cooled by a refrigerant such as dry ice. The cooling region 31 may be a region that does not include the end portions 13a and 13b.

  As described above, when the repair pipe 20 is cooled, the repair pipe 20 tends to shrink due to heat shrinkage, but both ends 21 of the repair pipe 20 are constrained by the pipes 11 connected to the upper and lower sides thereof. Therefore, a tensile force is given to the repair pipe 20 along the extending direction of the repair pipe 20 due to thermal stress. When the tensile stress acting on the repair pipe 20 exceeds the yield point of the repair pipe 20 in this way, the repair pipe 20 yields, so the residual stress of the repair pipe 20 when the temperature of the repair pipe 20 returns to room temperature. Compared to before the repair pipe 20 yields. Thereby, the residual stress generated in the repair pipe 20 can be reduced.

In the above case, an example in which the repair pipe 20 is cooled has been shown. However, when the periphery of the repair pipe 20 is heated, the repair pipe 20 is yielded and the temperature around the repair pipe 20 returns to room temperature. The residual stress of the repair pipe 20 can be reduced.
That is, as a stress relaxation measure, after the repair pipe 20 is attached to the furnace wall 10 with a predetermined section removed by welding, an adjacent pipe 11A (see FIG. 9) adjacent to the repair target pipe 13 including the repair target portion 14 is included. The repair tube 20 may be yielded by heating a predetermined range of the furnace wall 10 and applying a tensile force to the repair tube 20. The predetermined range is, for example, the heating range 18 shown in FIG.
As described above, after the repair pipe 20 is attached by welding, the predetermined range (heating range 18) of the furnace wall 10 including the adjacent pipe 11A adjacent to the repair pipe 20 is heated, so that the repair is performed by the thermal elongation of the heating range 18. The repair pipe 20 can be yielded by applying a pulling force to the pipe 20. When the temperature of the heating range 18 returns to room temperature, the residual stress of the repair pipe 20 is reduced as compared to before the repair pipe 20 is yielded. Thereby, the residual stress generated in the repair pipe 20 can be reduced.

  As mentioned above, about other embodiment of the repair method of the furnace wall, the excision area 15 was demonstrated as what is a straight pipe | tube part, and the repair pipe | tube 20 does not have the curved part 22. FIG. However, the cut section 15 may include the curved portion 22, and the repair pipe 20 may have the curved portion 22. That is, the stress relaxation measure implemented in step S20 in another embodiment of the furnace wall repair method can also be applied to the furnace wall repair methods according to some embodiments shown in FIGS. FIG. 11 shows a case where the stress relaxation measure implemented in step S20 in another embodiment of the furnace wall repair method is applied to the furnace wall repair method according to some embodiments shown in FIGS. It is a flowchart which shows the outline flow of. This furnace wall repair method includes a stress relaxation measure in addition to step S1 for selecting a repair target location shown in FIG. 2, step S3 for cutting a predetermined section, and step S5 for attaching both ends of the repair pipe by welding. Step S30 is provided.

  In step S30 in which stress relaxation measures are implemented, the tensile stress generated in the repair pipe 20 due to shrinkage after welding at both ends 21 of the repair pipe 20 after the repair pipe 20 is attached to the furnace wall 10 with a predetermined section removed by welding. In order to reduce the stress, a stress relaxation measure is performed in which at least one of cooling of the repair pipe 20 and heating of the furnace wall 10 from which a predetermined section is cut is performed.

  For convenience of illustration, in the flowchart of FIG. 11, it is described as if step S <b> 30 for implementing stress relaxation measures is performed after step S <b> 5 for attaching both ends of the repair pipe by welding. As in the embodiment according to the flowchart, step S30 of implementing stress relaxation measures may be performed before step S5 of attaching both ends of the repair pipe by welding, and step S5 of attaching both ends of the repair pipe by welding. In parallel with the implementation of step S30, step S30 of implementing a stress relaxation measure may be performed.

That is, in step S30 for implementing the stress relaxation measure, the repair pipe 20 before being attached to the furnace wall 10 may be cooled as described above. And in step S5 which attaches the both ends of a repair pipe by welding, you may make it attach the repair pipe 20 in the state cooled by step S30 which implements a stress relaxation measure by welding.
Further, in step S30 for implementing the stress relaxation measure, the heating range 18 may be heated as described above. And in the state which heated the heating range 18, step S5 which attaches the both ends of a repair pipe by welding may be implemented, and you may make it attach the both ends 21 of the repair pipe 20 by welding.
Moreover, in step S30 which implements a stress relaxation measure, as mentioned above, the repair pipe 20 after being welded to the furnace wall 10 from which a predetermined section has been cut is cooled and repaired by applying a tensile force due to thermal stress. The tube 20 may yield.
Thus, the residual stress which arises in the repair pipe | tube 20 can further be reduced by implementing step S30 which implements a stress relaxation measure.

The present invention is not limited to the above-described embodiments, and includes forms obtained by modifying the above-described embodiments and forms obtained by appropriately combining these forms.
For example, the repair pipe 20 shown in FIG. 4B has a first curved portion 22a to a fourth curved portion 22d and a first straight portion 23a to a fifth straight portion 23e, but the first straight portion 23a to the second straight portion 23e. At least one of the five straight portions 23e may not be provided.
Further, for example, in FIG. 6, the excision section 15 is set so as to include one curved portion 22 of the curved pipe portion 11c, but the excision section 15 may be set so as to include the entire curved pipe portion 11c.

5a, 5b Welded part 10 Furnace wall 11 Pipe 12 Fin 13 Repair target pipe 14 Repair target part 15 Cutting section 20 Repair pipe 21 Both ends 20A First repair pipe 25a One end side bent part 25b The other end side bent part 26 Middle part

Claims (10)

A method for repairing a furnace wall composed of a plurality of pipes,
Selecting a repair target location in the plurality of pipes;
Excising a predetermined section of the pipe to be repaired, which is the pipe including the repair target part;
Attaching the both ends of the repair pipe having a curved portion to the repair target pipe from which the predetermined section has been removed by welding; and
Equipped with a,
The predetermined section is a part of a straight pipe portion in the repair target pipe,
The repair pipe is
An upper straight portion having an end attached to an upper end portion of the pipe to be repaired as one end, and an upper straight portion extending along a longitudinal direction of the straight pipe portion in the pipe to be repaired;
A lower straight part having an end attached to the lower end of the pipe to be repaired as the other end, and extending along a longitudinal direction of the straight pipe part in the pipe to be repaired When,
A plurality of curved portions formed integrally with the upper straight portion and the lower straight portion between the other end of the upper straight portion and one end of the lower straight portion;
How to repair the furnace wall. A method for repairing a furnace wall composed of a plurality of pipes,
Selecting a repair target location in the plurality of pipes;
Cutting out a predetermined section of the pipe including the repair target portion;
Attaching both ends of a repair pipe having a curved portion to the furnace wall from which the predetermined section has been cut by welding;
Equipped with a,
In the step of selecting the repair target location, a location where the degree of wear in the pipe is greater than or equal to a specified wear level is selected as the repair target location,
In the step of cutting out the predetermined section of the pipe, if the pipe including the repair target portion is a pipe including a curved pipe part, even if the degree of wear of the curved pipe part is less than the specified wear degree A method for repairing a furnace wall, wherein a section including at least a part of the curved pipe portion is set as the predetermined section, and the predetermined section is excised . A method for repairing a furnace wall composed of a plurality of pipes,
Selecting a repair target location in the plurality of pipes;
Cutting out a predetermined section of the pipe including the repair target portion;
Attaching both ends of a repair pipe having a curved portion to the furnace wall from which the predetermined section has been cut by welding;
Equipped with a,
In order to reduce the tensile stress generated in the repair pipe due to the shrinkage after the welding at both ends of the repair pipe after the repair pipe is attached to the furnace wall where the predetermined section is cut by welding, The furnace wall repairing method further comprising the step of implementing a stress relaxation measure for performing at least one of cooling and heating the furnace wall from which the predetermined section has been cut . The predetermined section is a straight pipe portion in the plurality of pipes.
The method for repairing a furnace wall according to claim 3 . The repair pipe is
One end side bend formed on one end side of the repair pipe,
Including a first repair pipe having the other end side bent portion formed on the other end side of the repair pipe, and an intermediate portion formed between the one end side bent portion and the other end side bent portion,
In the step of attaching both ends of the repair pipe by welding, the first repair pipe is attached to the furnace wall from which the predetermined section has been cut so that the intermediate portion protrudes toward the outside of the furnace.
The method for repairing a furnace wall according to claim 3 or 4 . A method for repairing a furnace wall composed of a plurality of pipes,
Selecting a repair target location in the plurality of pipes;
Cutting out a predetermined section of the pipe including the repair target portion;
Attaching both ends of the repair pipe to the furnace wall from which the predetermined section has been removed by welding;
At least one of cooling of the repair pipe and heating of the furnace wall from which the predetermined section has been cut in order to reduce tensile stress generated in the repair pipe due to shrinkage after welding at both ends of the repair pipe Implementing stress relief measures to do one of the following;
A method for repairing a furnace wall. In the step of implementing the stress relaxation measure, the repair pipe is cooled,
The method for repairing a furnace wall according to claim 6, wherein in the step of attaching both ends of the repair pipe by welding, the repair pipe that has been cooled in the step of implementing the stress relaxation measure is attached by welding. The furnace wall includes fins connecting adjacent pipes,
In the step of implementing the stress relaxation measure, a predetermined range of the furnace wall including an adjacent pipe adjacent to the pipe including the repair target portion is heated,
In the step of attaching both ends of the repair pipe by welding, the repair pipe is welded to the furnace wall from which the predetermined section is cut in a state where the predetermined range of the furnace wall is heated in the step of implementing the stress relaxation measure. The method for repairing a furnace wall according to claim 6, wherein the furnace wall is attached at a step. In the step of implementing the stress relaxation measure, the repair pipe is cooled by attaching the repair pipe to the furnace wall from which the predetermined section has been cut, and a tensile force is applied by thermal stress to thereby provide the repair pipe. The method for repairing a furnace wall according to claim 6, wherein In the step of implementing the stress relaxation measure, after the repair pipe is attached to the furnace wall where the predetermined section is cut by welding, the furnace wall including the adjacent pipe adjacent to the pipe including the repair target portion The furnace wall repair method according to claim 6, wherein the repair pipe is yielded by heating a predetermined range and applying a tensile force to the repair pipe.

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