WO2019176641A1

WO2019176641A1 - Method for replacing furnace wall tube

Info

Publication number: WO2019176641A1
Application number: PCT/JP2019/008561
Authority: WO
Inventors: 正数松井
Original assignee: 三菱日立パワーシステムズ株式会社
Priority date: 2018-03-12
Filing date: 2019-03-05
Publication date: 2019-09-19
Also published as: JP2019158220A; CN111919060B; CN111919060A; JP7164310B2; PH12020551414A1

Abstract

This method for replacing a furnace wall tube of a furnace wall of a boiler comprises: an identification step for identifying a furnace wall replacement portion which contains a furnace wall tube replacement portion, which is a portion of the length direction of at least one of a plurality of furnace wall tubes; a cutting step for cutting the furnace wall replacement portion from the outside of the furnace of the boiler; a removal step for removing the cut furnace wall replacement portion from the furnace wall to the outside of the furnace of the boiler; a first welding step for circumferentially welding, from the outside of the furnace of the boiler, a furnace wall tube renewal portion which corresponds to the furnace wall replacement portion which was removed from the furnace wall, and the furnace wall tube from which the furnace wall replacement portion was removed; and a second welding step for fitting a fin part renewal portion, which corresponds to a portion of a fin part contained in the furnace wall replacement portion removed from the furnace wall, from the outside of the furnace of the boiler into the furnace wall and welding the result after the first welding step.

Description

How to replace a furnace wall tube

The present disclosure relates to a method for replacing a furnace wall tube of a furnace wall of a boiler.

If the furnace wall tube of the boiler wall of the boiler deteriorates or damages such as cracks occur in the furnace wall tube, it is necessary to replace the relevant part of the furnace wall tube. As shown in FIG. 12, the furnace wall tube replacement work is usually performed after the boiler operation is stopped, a scaffold 101 is installed in the furnace furnace 100, and

workers

103 and 104 are respectively connected to the furnace furnace 100 and the furnace outside. From 102, the furnace wall tube 105 is replaced. In this method, since it takes time to install the scaffold 101, the construction period becomes long. As a result, the boiler stop period also becomes long, and the loss due to the boiler stop increases. In order to shorten the construction period, it is necessary to make it unnecessary to install the scaffold 101 in the furnace furnace 100 by performing the work by the worker only from the furnace outside 102 side.

On the other hand, in Patent Document 1, when repairing and welding a damaged boiler furnace wall tube (damaged tube) during boiler operation, the damaged portion of the damaged tube is cut and removed, a new tube is inserted, and the existing tube is inserted. And a method of welding a new pipe from the outside of the furnace wall. In this method, an opening that allows a part of the small automatic TIG welding torch head to be inserted into the inner surface of the pipe is formed on the outer wall side of the circumferential groove around the circumferential joint of the existing pipe and the new pipe. First, from the inner surface of the pipe excluding the opening, automatic TIG welding is performed with the inserted welding torch from the inner surface of the pipe, and then the insertion pipe that fits the opening is temporarily attached to the opening, and then the outer circumference of the temporary attachment part of the insertion pipe Describes that manual TIG welding is performed.

Japanese Patent No. 3615826

However, in the method described in Patent Document 1, after opening an opening for inserting the automatic TIG welding torch head into the pipe and performing welding, an insertion tube that fits the opening is temporarily attached to the opening. It is necessary to perform manual TIG welding on the outer periphery of the temporary attachment portion of the insertion tube.

In view of the above circumstances, at least one embodiment of the present disclosure aims to provide a method of replacing a furnace wall tube that can shorten the work period.

(1) A method of replacing a furnace wall tube according to at least one embodiment of the present invention includes:
A method of replacing a furnace wall tube of a boiler furnace wall,
The furnace wall is
A plurality of furnace wall pipes spaced from each other;
A plate-like fin portion connecting adjacent furnace wall tubes,
The method
Identifying a furnace wall replacement portion including a furnace wall tube replacement portion that is a portion of at least one length of the plurality of furnace wall tubes;
A cutting step of cutting the furnace wall replacement part from the furnace outside of the boiler,
A removal step of removing the cut furnace wall replacement part from the furnace wall to the outside of the furnace of the boiler;
First welding that circumferentially welds a furnace wall tube renewal portion corresponding to the furnace wall tube replacement portion removed from the furnace wall and a furnace wall tube from which the furnace wall replacement portion has been removed from the outside of the furnace of the boiler. Steps,
After the first welding step, a fin portion update portion corresponding to a part of the fin portion included in the furnace wall replacement portion removed from the furnace wall is fitted into the furnace wall from the furnace outer side of the boiler. And a second welding step for welding.

According to the above method (1), the furnace wall tube can be exchanged only from the outside of the boiler, and there is no need to install a scaffold inside the boiler furnace. It can be shortened.

(2) In some embodiments, in the method of (1) above,
A part of the fin portion included in the furnace wall replacement portion extends so as to protrude in the length direction of the furnace wall tube replacement portion from both ends of the furnace wall tube replacement portion.

When the furnace wall tube renewal part and the furnace wall tube are circumferentially welded from the outside of the boiler furnace, a welding device equipped with a welding head inserted between adjacent furnace wall tubes is used. It is necessary to insert a part of the welding apparatus between the adjacent furnace wall pipes located on the opposite side of the furnace wall pipe renewal part with respect to the welding part in the length direction of the wall pipe. According to the method of (2) above, a part of the fin portion extending so as to protrude in the length direction of the furnace wall tube replacement portion is removed from both ends of the furnace wall tube replacement portion, whereby the furnace wall tube Since a gap in which a part of the welding apparatus can be inserted is formed between adjacent furnace wall pipes located on the opposite side of the furnace wall pipe renewal part with respect to the welding part in the length direction of the welding apparatus, It can be installed so that it can be circumferentially welded.

(3) In some embodiments, in the method of (1) or (2) above,
In each of the first welding step and the second welding step, the furnace wall tube update part and the fin part update part are covered with a covering member from at least one of the inside of the furnace of the boiler or the outside of the furnace of the boiler. Welding is performed.

When replacing the furnace wall tube, wind may blow from the inside of the boiler to the outside of the furnace or from the outside of the furnace to the inside of the furnace. When such a wind blows, the shielding gas is disturbed and welding cannot be performed properly. According to the method of (3) above, by performing welding in a state where the furnace wall tube renewal part and the fin part renewal part are covered with a covering member from at least one of the inside of the boiler or the outside of the boiler, the inside of the boiler Even if wind blows from the outside of the furnace to the outside of the furnace or from the outside of the furnace to the inside of the furnace, the disturbance of the shield gas can be suppressed by the covering member, so that welding can be performed appropriately.

(4) In some embodiments, in any of the above methods (1) to (3),
In the first welding step, circumferential welding is performed in a state in which foam foam is inserted into the furnace wall tube from the cut end portion of the furnace wall tube from which the furnace wall tube replacement part has been removed.

During the furnace wall tube replacement work, the air that has circulated inside the furnace wall tube may blow as wind from the cut end. When such a wind blows, the shielding gas is disturbed and welding cannot be performed properly. According to the method of (4) above, the wind blown from the cut end is suppressed by inserting the foam foam into the furnace wall tube from the cut end, so that the turbulence of the shield gas is suppressed and the welding is appropriately performed. Can be done.

(5) In some embodiments, in any of the above methods (1) to (4),
Further comprising a groove processing step before the first welding step;
The groove processing step includes
Performing groove processing on the cut end portion of the furnace wall tube from which the furnace wall tube replacement part has been cut;
And performing a groove process on both ends of the furnace wall tube renewal portion.

According to the method of (5) above, the furnace wall tube renewal portion and the furnace wall tube are welded by performing groove processing on both the cut end portion of the furnace wall tube and the end portion of the furnace wall tube renewal portion. It is possible to increase the welding strength.

(6) In some embodiments, in the method of (5) above,
A V-shaped groove is grooved on one of the cut end and the end of the furnace wall tube renewal portion welded to the cut end, and a U-shaped groove is grooved on the other. Is done.

According to the method of (6) above, the tolerance of the groove gap compared to the case where both the cut end portion and the end portion of the furnace wall tube renewal portion are grooved into a V-shaped groove or a U-shaped groove. The back wave can be formed satisfactorily while increasing the thickness.

(7) In some embodiments, in the method of (5) or (6) above,
After the groove processing step, tack welding is performed in which the groove processed at the cut end and the groove processed at the end of the furnace wall tube update portion are tack-welded in a state of facing each other. The method further includes a step.

According to the method of (7) above, the furnace wall is obtained by tack welding with the groove processed at the cut end and the groove processed at the end of the furnace wall tube renewal portion facing each other. Prior to the circumferential welding of the tube renewal portion and the furnace wall tube, it is possible to reduce the gap and the groove gap in the circumferential direction of the furnace wall tube.

According to at least one embodiment of the present disclosure, the furnace wall tube can be exchanged only from the outside of the furnace of the boiler, and there is no need to install a scaffold inside the furnace of the boiler. The work period can be shortened.

It is the front view which looked at some furnace wall of the boiler containing the furnace wall pipe exchanged by the method of replacing the furnace wall pipe which concerns on Embodiment 1 of this indication from the furnace outer side of the boiler. It is a flowchart for demonstrating the method to replace | exchange the furnace wall pipe which concerns on Embodiment 1 of this indication. A portion of the boiler wall tube replacement portion and the fin portion replacement portion removed from the furnace wall of the boiler including the furnace wall tube replaced by the furnace wall tube replacement method according to the first embodiment of the present disclosure is the boiler furnace. It is the front view seen from the outside. A front view of a part of the state in which the furnace wall tube update part is welded to the furnace wall of the boiler including the furnace wall tube replaced by the method of replacing the furnace wall tube according to Embodiment 1 of the present disclosure as viewed from the outside of the boiler furnace. FIG. In the method of replacing | exchanging the furnace wall tube which concerns on Embodiment 1 of this indication, it is a figure which shows the state which carries out the circumference welding of the furnace wall tube replacement | exchange part from the furnace outer side of a boiler to the furnace wall of a boiler. It is a figure for demonstrating operation | movement of the torch part of the circumference welding apparatus used for the method of replacing | exchanging the furnace wall pipe which concerns on Embodiment 1 of this indication. A portion of the boiler wall tube in which the furnace wall tube renewal portion and the fin portion renewal portion are welded to the furnace wall of the boiler including the furnace wall tube to be replaced by the method for replacing the furnace wall tube according to the first embodiment of the present disclosure is used. It is the front view seen from the outside. It is a flowchart for demonstrating the method to replace | exchange the furnace wall pipe which concerns on Embodiment 2 of this indication. It is a figure which shows the example of the groove shape which can be formed in the cutting | disconnection edge part of a furnace wall pipe, and the edge part of a furnace wall pipe update part in the method to replace the furnace wall pipe which concerns on Embodiment 2 of this indication. It is a figure which shows the example of the groove shape which can be formed in the cutting | disconnection edge part of a furnace wall pipe, and the edge part of a furnace wall pipe update part in the method to replace the furnace wall pipe which concerns on Embodiment 2 of this indication. It is a figure which shows the example of the groove shape which can be formed in the cutting | disconnection edge part of a furnace wall pipe, and the edge part of a furnace wall pipe update part in the method to replace the furnace wall pipe which concerns on Embodiment 2 of this indication. It is a figure for demonstrating operation | movement of tack welding in the method of replacing | exchanging the furnace wall pipe which concerns on Embodiment 2 of this indication. It is sectional drawing which shows an example of the operation | movement which performs circumferential welding in the method of replacing | exchanging the furnace wall pipe which concerns on Embodiment 2 of this indication. It is a figure for demonstrating the conventional method of replacing | exchanging a furnace wall pipe.

Hereinafter, some embodiments of the present invention will be described with reference to the drawings. However, the scope of the present invention is not limited to the following embodiments. The dimensions, materials, shapes, relative arrangements, and the like of the component parts described in the following embodiments are not merely intended to limit the scope of the present invention, but are merely illustrative examples.

(Embodiment 1)
FIG. 1 is a front view of a part of a furnace wall 1 of a boiler including a furnace wall pipe 2 to be replaced by the method for replacing a furnace wall pipe according to Embodiment 1 of the present disclosure as viewed from the outside of the boiler. Has been. The furnace wall 1 includes a plurality of furnace wall tubes 2 that extend in the vertical direction and are spaced from each other, and plate-like fin portions 3 that connect adjacent furnace wall tubes 2.

Next, a method for replacing the furnace wall tube according to the first embodiment will be described based on the flowchart of FIG.
First, the furnace wall replacement part 8 (see FIG. 1), which is the part to be replaced, is specified, and the furnace wall replacement part 8 is marked (step S1 (specific step)). In FIG. 1, the marking 6 indicating the range of the furnace wall replacement portion 8 is exemplarily drawn by a broken line. However, the marking 6 does not necessarily have to be a broken line. It may be a form.

In the furnace wall 1, the furnace wall replacement portion 8 is a furnace wall tube replacement portion 4 that is a part of the length of the furnace wall tube 2 and a part of the fin portion 3 that is connected to the furnace wall tube replacement portion 4. The fin part replacement part 5 is included. In FIG. 1, the number of furnace wall tubes 2 including the furnace wall tube replacement part 4 is two. However, the number of the furnace wall tubes 2 is not limited to two. Also good. The fin portion replacement portion 5 is provided between the furnace wall tube 2 including the furnace wall tube replacement portion 4 and the furnace wall tube 2 ′ adjacent to the furnace wall tube 2 and not including the furnace wall tube replacement portion 4. It extends so as to protrude in the length direction of the furnace wall tube replacement portion 4 from both

end portions

4 a and 4 a of the wall tube replacement portion 4. When there are two or more furnace wall tubes 2 including the furnace wall tube replacement portion 4, the fin portion replacement portion 5 is disposed between the adjacent

furnace wall tubes

2 and 2 at both ends 4 a of the furnace wall tube replacement portion 4. , 4a extends so as to protrude in the length direction of the furnace wall tube replacement part 4.

As shown in FIG. 2, after marking 6 in step S 1, the furnace wall replacement portion 8 is cut along the marking 6 from the outside of the boiler using an arbitrary cutting device (step S 2 (cutting step )). After cutting along the marking 6, the cut furnace wall replacement part 8 is removed to the outside of the boiler (step S3 (removal step)).

As shown in Fig. 3, through the operations of steps S2 and S3, the furnace wall 1 is formed with an opening hole 7 that communicates the furnace outside and the furnace inside of the boiler. When the furnace wall tube replacement part 4 (see FIG. 1) is removed, the interior of the furnace wall tube 2 is opened at the end of the furnace wall tube 2 from which the furnace wall tube replacement part 4 (see FIG. 1) has been removed. A cut end 12 is formed. Further, by removing the fin portion replacement portion 5 (see FIG. 1), the furnace wall tube 2 including the furnace wall tube replacement portion 4 and the furnace wall tube replacement portion 4 are not included while adjacent to the furnace wall tube 2. Between the furnace wall pipes 2 ′, gaps 10 extending in the vertical direction upward and downward from the respective cut ends 12 are formed. When there are two or more furnace wall tubes 2 including the furnace wall tube replacement part 4, there are gaps 10 extending between the adjacent

furnace wall tubes

2 and 2 in the vertical direction above and below the respective cut ends 12. Composed. Each gap 10 is a part of the opening hole 7.

As shown in FIG. 2, after step S 3, a furnace wall tube renewal portion 14 (see FIG. 4) corresponding to the furnace wall tube replacement portion 4 and the furnace wall tube 2 from which the furnace wall tube replacement portion 4 has been removed. Welding from the outside of the furnace of the boiler (step S4 (first welding step)). As shown in FIG. 4, the furnace wall tube renewal portion 14 and the furnace wall tube 2 are opposed to the end portion of the furnace wall tube renewal portion 14 and the cut end portion 12 (see FIG. 3) of the furnace wall tube 2. In this way, circumferential welding is performed, and the welded portion 15 is formed along the outer peripheral surface of the furnace wall tube renewal portion 14 and the furnace wall tube 2.

FIG. 5 shows a circumferential welding device 20 for circumferential welding of the furnace wall tube renewal portion 14 and the furnace wall tube 2. The circumferential welding device 20 is electrically connected to the power source 21 and the operation panel 22 installed on the outside of the furnace of the boiler, the power source 21 via the wiring 23, and from the outside of the boiler to the furnace wall tube renewal portion 14 and And a welding head portion 24 configured to be installed on the furnace wall tube 2. For example, an apparatus disclosed in Japanese Patent No. 4442763 can be used as the circumferential welding apparatus 20.

Since the welding head portion 24 is installed so as to surround the outer peripheral surface of the furnace wall tube renewal portion 14 and the furnace wall tube 2, a part of the welding head portion 24 is located in the gap 10. As described above, by removing the fin portion replacement portion 5 (see FIG. 1) that is removed from the furnace wall 1, it is more vertical than the cut end 12 between the

adjacent furnace walls

2, 2 and between the

furnace walls

2, 2 ′. Since the gap 10 is configured to extend upward and downward in the direction, the welding head portion 24 can be installed so as to be capable of circumferential welding.

As shown in FIG. 6, the welding head portion 24 includes a furnace wall tube renewal portion 14 and a torch portion 30 that can rotate along the outer peripheral surface of the furnace wall tube 2 (see FIG. 5). The torch part 30 includes a torch body 31, a ceramic plate 32 provided on the torch body 31, and an electrode 33 provided so as to protrude from the ceramic plate 32. The torch portion 30 moves from the gap 10 to the inside of the boiler along the outer peripheral surface of the furnace wall tube renewal portion 14 and the furnace wall tube 2 and welds while moving to the outside of the boiler through the adjacent gap 10. By doing so, circumferential welding is performed.

As shown in FIG. 2, after step S 4, the fin portion update portion 16 (see FIG. 7) corresponding to the fin portion replacement portion 5 is fitted into the portion where the fin portion replacement portion 5 is removed from the outside of the furnace of the boiler. (Step S5 (second welding step)). As shown in FIG. 7, the fin update portion 16 includes a furnace wall tube update portion 14, a furnace wall tube 2 to which the furnace wall tube update portion 14 is welded, a fin portion 3, and a furnace wall tube 2 ′. By welding, a welded portion 17 is formed along the outer edge of the fin update portion 16. Since the function of the fin portion 3 is to prevent gas leakage from the inside of the furnace of the boiler, it is sufficient to weld the fin portion update portion 16 only from the outside of the furnace wall 1.

During the welding operation in steps S3 and S4, wind may blow from the inside of the boiler to the outside of the furnace or from the outside of the furnace to the inside of the furnace. When such a wind blows, the shielding gas is disturbed and welding cannot be performed properly. For this reason, in order to suppress the disturbance of the shield gas due to such wind, welding can be performed in a state where the furnace wall tube renewal portion 14 and the fin portion renewal portion 16 are covered with the covering member. The covering member may be installed inside the boiler furnace, outside the boiler furnace, or both inside and outside the boiler furnace.

When installing a covering member inside the furnace of the boiler, in order to recover the covering member to the outside of the boiler after the furnace wall tube renewal portion 14 is welded, a narrow gap 10 must be interposed. For this reason, it is preferable to use a sheet-like covering member (for example, a curtain disclosed in Japanese Utility Model Laid-Open No. 7-15162) that can be folded so as to be able to pass through the gap 10. In this case, since circumferential welding cannot be performed unless a certain distance is left between the sheet-like covering member and the furnace wall tube update part 14 and the fin part update part 16, in order to ensure such a distance, Arbitrary spacers are preferably arranged between the sheet-like covering member and the furnace wall tube update part 14 and the fin part update part 16.

On the other hand, when the cover member is installed outside the furnace of the boiler, a sheet-like cover member and a spacer provided inside the boiler furnace may be used. However, when the cover member is provided outside the boiler furnace, the installation space is limited by the furnace. Since it is often less than the inside, a box-shaped covering member (for example, a shield box disclosed in Japanese Patent Laid-Open No. 11-277238) can be used.

Thus, welding is performed in a state in which the furnace wall tube renewal portion 14 and the fin portion renewal portion 16 are covered with the covering member from at least one of the inside of the furnace of the boiler or the outside of the furnace of the boiler. Even if wind blows from the outside of the furnace to the inside of the furnace, the shielding gas can be prevented from being disturbed by the covering member, so that welding can be appropriately performed.

Also, during the welding operations in steps S3 and S4, the air that has circulated through the furnace wall tube 2 may blow from the cut end 12 as wind. Even when such a wind blows, the shield gas is disturbed and welding cannot be performed properly. Therefore, circumferential welding is performed with a foam foam (for example, a gas shielding foaming agent, Sunfoam P-30, Sugimura Chemical Co., Ltd.) inserted from the cut end 12 of the furnace wall tube 2 into the furnace wall tube 2. Preferably it is done. By inserting the foam foam from the cut end 12 into the furnace wall tube 2, the wind blown from the cut end 12 is suppressed, so that the disturbance of the shield gas is suppressed and welding can be performed appropriately.

In this way, the furnace wall tube 2 can be replaced only from the outside of the boiler furnace, and there is no need to install a scaffold inside the boiler furnace, thereby shortening the work period for replacing the furnace wall tube 2. Can do.

(Embodiment 2)
Next, a method for replacing the furnace wall tube according to the second embodiment will be described. The method for exchanging the furnace wall tube according to the second embodiment is the same as that of the first embodiment except that a step of performing groove processing on the furnace wall tube 2 and the furnace wall tube update portion 14 is added before circumferential welding. . In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

As shown in the flowchart of FIG. 8, the method for exchanging the furnace wall tube according to the second embodiment is the same as that of the first embodiment in steps S1 to S3. In the second embodiment, after step S3 is finished, groove processing is performed on the cut end portion 12 (see FIG. 3) of the furnace wall tube 2 and the end portion of the furnace wall tube update portion 14 (step S11 (groove processing step)). ).

As shown in FIG. 9A, a V-shaped groove may be grooved at each of the cut end portion 12 of the furnace wall tube 2 and the end portion of the furnace wall tube update portion 14, or as shown in FIG. 9B. In addition, a U-shaped groove may be grooved on each of the cut end portion 12 of the furnace wall tube 2 and the end portion of the furnace wall tube update portion 14. In general, a V-shaped groove has a wide tolerance for a groove gap, but there is a tendency that a back wave is not easily generated. On the other hand, the U-shaped groove can generally form a back wave well, but the tolerance for the groove gap tends to be narrow. Therefore, in order to obtain the advantages of both the V-shaped groove and the U-shaped groove, as shown in FIG. 9C, one of the cut end portion 12 of the furnace wall tube 2 or the end portion of the furnace wall tube renewal portion 14 is provided. It is preferable to groove the V-shaped groove and groove the U-shaped groove on the other side. As a result, both the cutting end 12 and the end of the furnace wall tube renewal portion 14 are improved while increasing the tolerance of the groove gap as compared with the case where the groove is processed into a V-shaped groove or a U-shaped groove. Waves can be formed well.

As shown in FIG. 8, after step S 11 is completed, the groove processed in the cut end portion 12 and the groove processed in the end portion of the furnace wall tube update portion 14 are temporarily attached to each other. Welding is performed (step S12 (tack welding step)). As shown in FIG. 10, using the groove aligning tool 40, the groove 12 a processed into the cut end 12 and the groove 14 a processed into the end of the furnace wall tube renewal portion 14 face each other. Match the condition.

The groove aligning device 40 includes a plate-like main body 41 having a recessed groove portion 42 into which the furnace wall tube 2 and the furnace wall tube renewal portion 14 can be fitted, and two

position adjusting members

43 and 44. Yes. A rectangular opening hole 45 is formed in the main body 41, and when the furnace wall tube 2 and the furnace wall tube renewal portion 14 are fitted in the recessed groove portion 42, a groove is formed from the outside of the boiler through the opening hole 45. 12a and 14a can be seen. The shape of the opening hole 45 is not limited to a rectangular shape, and may be an arbitrary shape as long as it does not hinder the tack welding work described later.

The

position adjusting members

43 and 44 have

U-shaped bolts

43a and 44a and nuts 43b, 43c and 44b, 44c that are screwed into the

U-shaped bolts

43a and 44a, respectively. The

U-shaped bolts

43a and 44a hook the furnace wall tube 2 and the furnace wall tube renewal portion 14 from the inside of the boiler furnace at their curved portions, respectively, and the two linear portions pass through the gap 10 to move the main body portion 41. The nuts 43b, 43c and 44b, 44c are screwed into the two linear portions from the outside of the boiler, and each nut is connected to the boiler of the main body 41. It is in contact with the outer surface 41a of the furnace. Circular plate-shaped

retaining portions

43d and 44d are provided at the ends of one of the linear portions of the

U-shaped bolts

43a and 44a, respectively. Thereby, even if the

U-shaped bolts

43a and 44a move to the inside of the boiler, it is possible to prevent the retaining

portions

43d and 44d from hitting the main body 41 and falling to the inside of the boiler.

When the tightening of each nut is adjusted, the relative values of the furnace wall tube 2 and the furnace wall tube renewal portion 14 with respect to each other are adjusted, so that the groove 12a and the groove 14a can be fixed to face each other. In this state, the groove 12a and the groove 14a are tack-welded through the opening hole 45 by TIG welding. By this tack welding, it is possible to reduce misalignments and groove gaps in the circumferential direction, and to keep the misalignments and groove gaps within the allowable values for the subsequent first welding step (see FIG. 8). it can. After the tack welding, the nuts 43b, 43c and 44b, 44c are loosened, and the groove aligning device 40 is removed from the furnace wall tube 2 and the furnace wall tube update portion 14.

As shown in FIG. 8, after step S12, steps S4 and S5 are performed in the same manner as in the first embodiment, and the replacement work of the furnace wall tube 2 is completed. In step S5, as shown in FIG. 11, circumferential welding may be performed by applying an annular insert ring 50 between the groove 12a and the groove 14a. By performing the circumferential welding by applying the insert ring 50, the back surface of the inner surface of the furnace wall tube 2 becomes smooth and uniform.

In the second embodiment, the same effects as those of the first embodiment can be obtained, and the furnace wall can be obtained by performing groove processing on both the cut end portion 12 of the furnace wall tube 2 and the both ends of the furnace wall tube renewal portion 14. The tube renewal portion 14 and the furnace wall tube 2 can be easily welded and the welding strength can be increased.

DESCRIPTION OF SYMBOLS 1 Furnace wall 2 Furnace wall pipe 3 Fin part 4 Furnace wall pipe exchange part 4a End part (furnace wall pipe exchange part) 5 Fin part exchange part 6 Marking 7 Open hole 8 Furnace wall exchange part 10 Crevice 12 Cutting edge part 12a Open Tip 14 Furnace wall tube renewal portion 14a Groove 15 Welding portion 16 Fin portion renewal portion 17 Welding portion 20 Circumferential welding device 21 Power supply 22 Operation panel 23 Wiring 24 Welding head portion 30 Torch portion 31 Torch body 32 Ceramic plate 33 Electrode 40 Open Pointing tool 41 Main body part 42 Groove part 43 Position adjustment member 43a U-type bolt 43b Nut 43c Nut 43d Retaining part 44 Position adjusting member 44a U-type bolt 44b Nut 44c Nut 44d Retaining part 45 Opening hole 50 Insert ring

Claims

A method of replacing a furnace wall tube of a boiler furnace wall,
The furnace wall is
A plurality of furnace wall pipes spaced from each other;
A plate-like fin portion connecting adjacent furnace wall tubes,
The method
Identifying a furnace wall replacement portion including a furnace wall tube replacement portion that is a portion of at least one length of the plurality of furnace wall tubes;
A cutting step of cutting the furnace wall replacement part from the furnace outside of the boiler,
A removal step of removing the cut furnace wall replacement part from the furnace wall to the outside of the furnace of the boiler;
First welding that circumferentially welds a furnace wall tube renewal portion corresponding to the furnace wall tube replacement portion removed from the furnace wall and a furnace wall tube from which the furnace wall replacement portion has been removed from the outside of the furnace of the boiler. Steps,
After the first welding step, a fin portion update portion corresponding to a part of the fin portion included in the furnace wall replacement portion removed from the furnace wall is fitted into the furnace wall from the furnace outer side of the boiler. A method of replacing a furnace wall tube, comprising: a second welding step of welding at a.
The part of the fin portion included in the furnace wall replacement portion extends so as to protrude in the length direction of the furnace wall tube replacement portion from both ends of the furnace wall tube replacement portion. 2. A method for exchanging a furnace wall tube according to 1.
In each of the first welding step and the second welding step, the furnace wall tube update part and the fin part update part are covered with a covering member from at least one of the inside of the furnace of the boiler or the outside of the furnace of the boiler. The method for replacing a furnace wall tube according to claim 1 or 2, wherein welding is performed.
In the first welding step, circumferential welding is performed in a state where foam foam is inserted into the furnace wall tube from the cut end portion of the furnace wall tube from which the furnace wall tube replacement part has been removed. 4. A method for exchanging a furnace wall tube according to any one of 3 above.
Further comprising a groove processing step before the first welding step;
The groove processing step includes
Performing groove processing on the cut end portion of the furnace wall tube from which the furnace wall tube replacement part has been cut;
The method of replacing a furnace wall tube according to any one of claims 1 to 4, further comprising a step of performing groove processing on both ends of the furnace wall tube update portion.
A V-shaped groove is grooved on one of the cut end and the end of the furnace wall tube renewal portion welded to the cut end, and a U-shaped groove is grooved on the other. A method for replacing a furnace wall tube according to claim 5.
After the groove processing step, tack welding is performed in which the groove processed at the cut end and the groove processed at the end of the furnace wall tube update portion are tack-welded in a state of facing each other. The method of replacing a furnace wall tube according to claim 5 or 6, further comprising a step.