JP2019015481A - Replacement method for boiler furnace wall, and temporal holding structure of boiler furnace wall - Google Patents

Abstract

To prevent occurrence of deformation or damage of a spiral pipe wall in replacing a part of a furnace wall portion in the spiral pipe wall with a furnace wall portion for replacement.MEANS FOR SOLVING THE PROBLEM: A boiler device comprises: a boiler furnace wall having a vertical pipe wall at its upper part and a spiral pipe wall 3 at its lower part; a back stay arranged around the spiral pipe wall 3, and supporting furnace pressure; a support member 8 fixed to the vertical pipe wall, and supporting the back stay. After the spiral pipe wall 3 below a part of a furnace wall portion 30 is fixed to the support member 8, and temporarily held, an outer edge of the part of the furnace wall portion 30 is cut out to extract the part of the furnace wall portion 30 from the spiral pipe wall 3, and then a furnace wall portion 31 for replacement is connected to a peripheral edge part of an opening 35 of the spiral pipe wall 3 formed by the extraction so as to block the opening 35.SELECTED DRAWING: Figure 5

Description

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

  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). Yes. The inclined water cooling wall is a membrane wall in which water pipes and fins are alternately welded in the same manner as the vertical water cooling wall, and is supported by being suspended from the vertical water cooling wall.

  Further, the support member is arranged in the vertical direction with respect to the inclined water cooling wall, and the panel side support fitting is joined to the inclined water cooling wall. The presser pin penetrates the hole of the panel side support bracket, and the panel side support bracket and the presser pin extend in the horizontal direction of the inclined water cooling 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 the elongation.

JP 60-164103 A

  In a coal-fired large-sized transformer once-through boiler, NOx reduction progresses remarkably, so that the vicinity of the furnace wall becomes a reducing atmosphere, and sulfidation corrosion occurs in the water pipe (heat transfer pipe) that constitutes the furnace wall. In recent years, such sulfidation corrosion has become prominent, and in order to prevent leakage (water leakage, water vapor leakage) from the water pipe, the corroded furnace wall is partially cut out by using a periodic inspection. It is necessary to replace it with an uncorroded furnace wall.

  However, in the boiler apparatus of Patent Document 1, the spiral tube wall (inclined water-cooled wall) is formed by a membrane wall in which a water tube and a fin extending obliquely with respect to the direction of gravity are welded and joined. It is inevitable that the strength is lower than that of the pipe wall (vertical water-cooled wall). Further, the load on the spiral tube wall is not transmitted to the upper vertical tube wall by the support member, but is transmitted to the vertical tube wall by the spiral tube wall itself. For this reason, when the corroded furnace wall portion of the spiral tube wall is cut out and a wide range of openings are provided in the spiral tube wall, there is no portion that transmits the load below the opening to the upper part of the boiler, so the load is on both sides of the opening. There is a possibility that stress concentration occurs by acting on the portion, and the spiral tube wall is deformed or damaged.

  Therefore, the present invention provides a boiler furnace wall that can prevent deformation and damage of the spiral tube wall when replacing a part of the spiral tube wall with a replacement furnace wall part. The purpose is to provide a replacement method and a boiler furnace wall temporary holding structure.

  In order to achieve the above object, a first aspect of the present invention is a boiler furnace wall having an upper vertical tube wall and a lower spiral tube wall suspended from the vertical tube wall, and disposed around the spiral tube wall. The boiler device includes a back stay that supports the furnace pressure and a support member that is fixed to the vertical tube wall and supports the back stay, and the support member is not fixed to the spiral tube wall and hangs in the vicinity of the outer surface of the spiral tube wall 1 is a boiler furnace wall replacement method in which a part of the spiral tube wall is replaced with a replacement furnace wall part, and includes a temporary holding process, a cutting process, and an attaching process.

  In the temporary holding step, the spiral tube wall below the part of the furnace wall portion is fixed to the support member and temporarily held. In the cutting process, after the temporary holding process, the outer edge of the part of the furnace wall part is cut and part of the furnace wall part is extracted from the spiral tube wall. In the attaching step, the replacement furnace wall portion is joined to the peripheral portion of the opening so as to close the opening of the spiral tube wall formed by the cutting step.

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

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

  In the above construction method, since the replacement furnace wall portion is joined to the peripheral edge of the opening so as to close the opening of the spiral tube wall, the temporary holding of the spiral tube wall with respect to the support member is released, so that the boiler apparatus can be operated at the time of operation. Unnecessary interference between the spiral tube wall and the support member can be prevented, and the support member can function in the same manner as before the 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 tube wall, and the second temporary wall is fixed to the support member. The spiral tube 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 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 are excised, and the supporting member and the first temporary holding member The temporary holding of the spiral tube wall is released by removing the second temporary holding member.

  In the construction method, in the temporary holding step, the first temporary holding member fixed to the spiral tube wall is welded and fixed to the second temporary holding member fixed to the support member by welding, and in the temporary holding releasing step, 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 are excised, and the second temporary holding is performed from the supporting member and the first temporary holding member. Since the temporary holding of the spiral tube wall is released by removing the member, the temporary holding of the spiral tube wall can be released by a simple operation. Further, since the first temporary holding member is left on the spiral tube wall side, damage to the spiral tube wall due to temporary holding release can be reliably prevented. Furthermore, since the second temporary holding member is removed, it is possible to reliably prevent unnecessary interference between the spiral tube wall and the support member during operation of the boiler device.

  According to a fourth aspect of the present invention, there is provided 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 the furnace pressure. In a boiler device comprising a stay and a support member that is fixed to the vertical tube wall and supports the back stay, the support member being suspended from the vicinity of the outer surface of the spiral tube wall without being fixed to the spiral tube wall, A boiler furnace wall temporary holding structure in which a spiral tube wall is temporarily held by a support member when a part of the furnace wall portion is replaced with a replacement furnace wall portion, and is fixed to the spiral tube wall. A temporary holding member; and a second temporary holding member fixed to the support member by welding. The first temporary holding member is fixed to the second temporary holding member by welding.

  In the above configuration, when a part of the spiral furnace wall is partially cut out and replaced with a replacement furnace wall part, the partial furnace wall part is cut out before the partial furnace wall part is cut out. Since the spiral tube wall below the wall portion is fixed and temporarily held with respect to the support member, in a state where a wide range of openings are formed in the spiral tube wall by cutting out some of the furnace wall portions, The load on the spiral tube wall is transmitted to the vertical tube wall via the support member. Therefore, the stress concentration on both sides of the opening is alleviated, and deformation and damage of the spiral tube wall can be prevented.

  Further, the first temporary holding member is fixed to the spiral tube 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 the replacement operation is completed, 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 are excised, and the supporting member and the first temporary holding member are removed. By removing the second temporary holding member from the member, the temporary holding of the spiral tube wall can be released by a simple operation. Further, since the second temporary holding member may be removed while the first temporary holding member remains on the spiral tube wall side, damage to the spiral tube wall due to temporary holding release can be reliably prevented. Furthermore, by removing the second temporary holding member, it is possible to reliably prevent unnecessary interference between the spiral tube wall and the support member during operation of the boiler device.

  According to the present invention, it is possible to prevent the spiral tube wall from being deformed or damaged when a part of the spiral tube wall is replaced with a replacement furnace wall portion.

It is a figure which shows the water cooling 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 tube wall, (a) is a side view of the part containing a panel side support metal fitting, (b) is an IIb direction arrow line view of Fig.2 (a). It is a III direction arrow directional view of Drawing 2 (a). It is a perspective view which shows an example of a backstay. It is a side view which shows the state which temporarily hold | maintained the downward direction of the furnace wall part of replacement | exchange object. It is the top view which looked at the temporary holding state of the spiral tube wall with respect to a vertical strap from the upper direction. It is a VII direction arrow line view of FIG. It is a side view which shows the state which cancel | released temporary holding of FIG.

  The furnace wall structure of the boiler apparatus which concerns on one Embodiment of this invention is demonstrated with reference to FIGS.

  As shown in FIG. 1, the furnace wall structure of the present embodiment includes a vertical pipe wall (vertical water wall) 2 formed at the upper part of the boiler furnace 1 and a vertical pipe wall 2 formed at the lower part of the boiler furnace 1. This is a combined water-cooled wall structure including a spiral tube wall (spiral water wall) 3 continuously suspended from the lower end. The boiler body including the vertical pipe wall 2 and the spiral pipe wall 3 is suspended from a ceiling beam in a structure (boiler building) made of steel columns and beams (not shown).

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

  In the spiral pipe wall 3, the water supply in the water pipe 6 rises while swirling around the boiler furnace 1, so that the amount of heat absorption 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 water. In addition, the spiral tube wall 3 has the advantage that the flow rate of the internal fluid can be increased because the number of water tubes 6 is smaller than that of the vertical tube wall 2, and the flow rate of the internal fluid can be increased. .

  In the vicinity of each outer surface of the spiral tube 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 has a U-shaped cross section that opens toward the outside of the furnace, and an upper portion thereof is fixed to the vertical pipe wall 2 by welding and hangs vertically downward. The spiral tube wall 3 is not fixed to the vertical strap 8, and the load of the spiral tube wall 3 is not transmitted to the upper vertical tube wall 2 by the vertical strap 8 but is transmitted to the vertical tube wall 2 by the spiral tube wall 3 itself. The

  Since the spiral tube wall 3 is a membrane wall in which the water tube 6 and the fins 7 extending obliquely with respect to the direction of gravity are welded, the strength of the spiral tube wall 3 itself is lower than that of the vertical tube wall 2. This is unavoidable, and combustion is performed in the furnace wall. Therefore, measures for preventing deformation in the width direction due to the furnace pressure and measures for absorbing heat elongation in the height direction due to thermal elongation are required. As a countermeasure, a backstay (a beam for supporting the furnace pressure inside the spiral tube wall 3) 10 is disposed around the spiral tube wall 3 so as to surround the outside of the spiral tube wall 3. (See FIG. 4). The backstay 10 is supported by the vertical strap 8, and the load of the backstay 10 is transmitted to the vertical pipe wall 2 through the vertical strap 8.

  FIG. 4 shows an example of the backstay 10. The back stay 10 shown in FIG. 4 includes a vertical back stay 11 that is arranged substantially in parallel with the vertical strap 8 and extends substantially vertically, and a horizontal back stay 12 that extends substantially horizontally, and the vertical back stay 11 and the horizontal back stay 12. Are crossed and connected to each other. The vertical back stay 11 and the horizontal back stay 12 are connected to the vertical strap 8 by a major link (swinging link) 13 and a minor link (swinging link) 14, and are connected to the vertical strap 8 through the major link 13 and the minor link 14. Supported.

  As shown in FIG. 1 (a), a plurality of panel-side support fittings 20 are fixed to the outer surface of the spiral tube wall 3. The plurality of panel-side support brackets 20 are provided at different positions with respect to the vertical straps 8.

  As shown in FIGS. 2 and 3, the panel-side support bracket 20 is composed of a pair of left and right support plates 21 and one presser pin 22, and the presser pins 22 are inserted into the left and right support plates 21. A pin insertion hole 23 is formed. The left and right support plates 21 are arranged on the left and right sides of the vertical strap 8 and are welded to a base plate 24 welded to the outer surface of the spiral tube wall 3. The presser pin 22 is arranged on the outer side of the vertical strap 8 with both ends thereof 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 pins 22 define a space 25 that surrounds 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 tube wall 3 and the vertical 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 (furnace wall part to be replaced) 30 due to a part of the spiral tube wall 3 corroded due to long-term use or the like. A method for replacing the portion 31 will be described with reference to FIGS.

  The replacement furnace wall portion 31 has the same shape and configuration as the replacement target furnace wall portion 30 and is manufactured in a factory or the like in accordance with the replacement target furnace wall portion 30. 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. It may be set, or may be set in a step shape so as to be substantially orthogonal to each axial direction (inclination direction) with respect to the plurality of water pipes 6 arranged vertically.

  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. However, in the following cutting process and mounting process, the replacement furnace wall part 31 is shown. In addition, the furnace wall portion 30 to be replaced may be divided and divided into a plurality of parts on the left and right and up and down and cut out and attached sequentially. At that time, the number and size of the partitions / divisions are not particularly limited.

  When exchanging the furnace wall part 30 to be exchanged with the furnace wall part 31 for exchange, first, the spiral tube wall 3 below the furnace wall part 30 to be exchanged is fixed to the vertical strap 8 and temporarily held (temporary). Holding step). The vertical strap 8 that temporarily holds the spiral tube wall 3 includes a vertical strap 8 that passes over the outer surface of the furnace wall portion 30 to be replaced, and a vertical strap 8 that passes through the left and right outer sides of the furnace wall portion 30 to be replaced. included.

  Specifically, on both the left and right sides of the vertical strap 8, a plurality of flat filler plates 32 are fixed to the outer surface of the spiral tube wall 3 (for example, the outer surface of the water tube 6 and / or the outer surface of the fin 7) by welding. A flat support plate (first temporary holding member) 33 is fixed to the outer surface of the plate 32 by welding, and a prismatic prism support (second temporary holding member, support column) 34 is welded to the outer surface of the vertical strap 8. The support plate 33 is fixed to the prism support 34 by welding.

  The plurality of filler plates 32 are adjusted and fixed so that their outer surfaces are arranged on the same plane. The support plate 33 is, for example, a rectangular steel plate having a plate thickness of 15 mm to 50 mm and a desired plate thickness and length selected from the range of a side length of 150 mm to 400 mm. Moreover, the prism support 34 is a prismatic steel material having a rectangular cross section (square or a rectangle close to a square) in which a desired length is selected from the range of one side having a length of 20 mm to 50 mm. The total length in the longitudinal direction (vertical direction) of the prism 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 tube wall 3. Moreover, it is preferable that the furnace wall portion 30 to be replaced is set so that the outer edge thereof does not pass through the panel side support fitting 20 (passes through a region removed 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 from the spiral tube wall 3 by a wire rope (not shown) (a cutting step). By such extraction, a wide range of openings 35 are formed in the spiral tube wall 3.

  Next, the replacement furnace wall portion 31 is lifted by a wire rope and joined to the peripheral portion of the opening 35 so as to close the opening 35 of the spiral tube wall 3 formed by extracting the furnace wall portion 30 to be replaced. (Installation process). At this time, the 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 replacement furnace wall portion 31 communicate in a watertight manner.

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

  Specifically, the welded portion 36 between the vertical strap 8 and the prismatic support 34 and the welded portion 37 between the support plate 33 and the prismatic support 34 are excised with a sander or the like, and the prismatic column 8 and the support plate 33 are removed from the prismatic column 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 a part of the furnace wall part 30 to be exchanged is partially cut out of the spiral tube wall 3 and replaced with the furnace wall part 31 for exchange, the furnace wall part 30 to be exchanged is changed. Prior to cutting, the spiral tube wall 3 below the furnace wall portion 30 to be replaced is fixed and temporarily held with respect to the vertical strap 8, so that the spiral tube wall 3 can be extensively removed by cutting the furnace wall portion 30 to be replaced. In the state in which the opening 35 is formed, the load on the spiral tube wall 3 below the opening 35 is temporarily stored in the vertical strap 8 and transmitted to the vertical tube wall 2 through the vertical strap 8. Therefore, the stress concentration on both side portions of the opening 35 is alleviated, and deformation and damage of the spiral tube wall 3 can be prevented.

  Further, after the replacement furnace wall portion 31 is joined to the peripheral portion 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 tube wall 3 and the vertical strap 8 at the time of the operation can be prevented, and the vertical strap 8 can be functioned even after the furnace wall portion 30 is replaced, as before the replacement.

  Further, the support plate 33 fixed to the spiral tube wall 3 is welded and fixed to the prism support 34 fixed to the vertical strap 8 by welding. In the temporary holding release process, the vertical strap 8 and the prism support 34 are fixed. The temporary holding of the spiral tube wall 3 is released by cutting the welded portion 36 between the support plate 33 and the welded portion 37 between the support plate 33 and the prism support 34 and removing the prism support 34 from the vertical strap 8 and the support plate 33. Therefore, the temporary holding of the spiral tube wall 3 can be released by a simple operation.

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

  In addition, this invention is not limited to the above-mentioned embodiment described as an example, and its Example, In the range which does not deviate from the technical idea which concerns on this invention even if it is other than the above-mentioned embodiment etc. If so, various changes can be made according to the design and the like.

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: Presser pin 23: Pin insertion hole 24: Base plate 25: Space 30: Part of the furnace wall (replacement object) Furnace wall part)
31: Replacement furnace wall portion 32: Filler plate 33: Support plate (first temporary holding member)
34: prism support (second temporary holding member, support column)
35: Opening 36: Welded portion between vertical strap and prism support 37: Welded portion between support plate and prism support

Claims (4)

A boiler furnace wall having an upper vertical pipe wall and a lower spiral pipe wall suspended from the vertical pipe wall; a backstay disposed around the spiral pipe wall to support furnace pressure; and the vertical pipe wall And a support member that supports the backstay, and the support member is not fixed to the spiral tube wall and hangs in the vicinity of the outer surface of the spiral tube wall. A boiler furnace wall replacement method for replacing the furnace wall part of the part with a replacement furnace wall part,
A temporary holding step of temporarily holding the spiral tube wall below the part of the furnace wall portion fixed to the support member;
After the temporary holding step, a cutting step of cutting an outer edge of the part of the furnace wall part and extracting the part of the furnace wall part from the spiral tube wall;
A boiler furnace wall replacement comprising: an attachment step of joining the replacement furnace wall portion to a peripheral edge portion of the opening so as to close the opening of the spiral tube wall formed by the cutting step. Construction method. The boiler furnace wall replacement method according to claim 1,
A boiler furnace wall replacement method, further comprising a temporary holding releasing step of releasing temporary holding of the spiral tube wall with respect to the support member after the attaching step. The boiler furnace wall replacement method according to claim 2,
In the temporary holding step, the first temporary holding member is fixed to the spiral tube 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 temporarily holding the spiral tube wall by welding and fixing the holding member;
In the temporary holding release step, 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 are cut out, and the supporting member And the temporary holding | maintenance of the said spiral tube wall is cancelled | released by removing the said 2nd temporary holding member from the said 1st temporary holding member. The replacement method of the boiler furnace wall characterized by the above-mentioned. A boiler furnace wall having an upper vertical pipe wall and a lower spiral pipe wall suspended from the vertical pipe wall; a backstay disposed around the spiral pipe wall to support furnace pressure; and the vertical pipe wall And a support member that supports the backstay, and the support member is not fixed to the spiral tube wall and hangs in the vicinity of the outer surface of the spiral tube wall. A boiler furnace wall temporary holding structure that temporarily holds the spiral tube wall by the support member when the furnace wall part of the part is replaced with a replacement furnace wall part,
A first temporary holding member fixed to the spiral tube wall;
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.

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