heat recovery boiler

Abstract

To reduce the manufacturing cost of heat recovery boilers. [Solution] The system comprises a water-cooled wall arranged around a gas flow path extending vertically and defining the gas flow path, and heat transfer tubes extending in the direction of tube extension having a horizontal component. The water-cooled wall has a plurality of water-cooled tubes extending vertically and spaced apart from each other, arranged horizontally along the edge of the gas flow path, and fins arranged between the plurality of water-cooled tubes. The fins are fixed to at least one of the water-cooled tubes which are adjacent to each other on both sides with respect to the fins. The fins have openings that penetrate in the direction of tube extension. The heat transfer tubes extend from the inside in the direction of extension, through the openings of the fins, to the outside in the direction of extension, and are supported in the fins at the lower edge portion of the openings.

Description

Technical Field

[0001] The present invention relates to a heat recovery boiler.

Background Art

[0002] A boiler generally includes a boiler casing that defines a gas flow path through which exhaust gas flows, and heat transfer tubes disposed in the gas flow path.

[0003] For example, the following Patent Document 1 discloses a heater as a boiler. Inside the gas flow path of this heater, in addition to the heat transfer tubes, a vertical pipe extending in the vertical direction, a first support fitting fixed to the vertical pipe, and a second support fitting fixed to the lower surface of the heat transfer tube are arranged. The second support fitting fixed to the heat transfer tube is supported by the first support fitting so as to be movable relative to the first support fitting fixed to the vertical pipe. That is, in the following Patent Document 1, the heat transfer tubes are supported by a support structure that is disposed in the gas flow path and includes the vertical pipe, the first support fitting, and the second support fitting.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of Invention

Problems to be Solved by the Invention

[0005] In the technique described in the above Patent Document 1, the number of components of the support structure that supports the heat transfer tubes increases, and in addition, this support structure is required to have corrosion resistance under high temperatures. For this reason, the technique described in the above Patent Document 1 increases the manufacturing cost of the boiler.

[0006] Accordingly, the present disclosure aims to provide a heat recovery boiler that can reduce manufacturing costs.

Means for Solving the Problems

[0007] A heat recovery boiler according to one embodiment of the invention for achieving the above objective is: The boiler casing covers the heat transfer tubes and comprises a water-cooled wall that defines a gas flow path through which exhaust gas can flow and which extends vertically; a heat transfer tube through which water can flow and which extends in a direction having a horizontal component, and which exchanges heat between the water and the exhaust gas flowing in the gas flow path; and a cover that is located on the outer side of the extension direction, which is the side of the gas flow path and the inner side of the extension direction with respect to the water-cooled wall, with respect to the water-cooled wall. The boiler casing covering the heat transfer tubes comprises the water-cooled wall and the cover. The water-cooled wall has a plurality of water-cooled tubes that extend vertically and are spaced apart from each other and arranged horizontally along the edge of the gas flow path, and fins arranged between the plurality of water-cooled tubes. The fins are fixed to at least one of the water-cooled tubes that are located adjacent to each of the water-cooled tubes on each side in the lateral direction perpendicular to the extension direction of the tube and where the plurality of water-cooled tubes are lined up, with respect to the fins. The fin has an opening that penetrates in the direction of the extension of the tube. The heat transfer tube extends from the inside in the direction of extension, through the opening in the fin, to the outside in the direction of extension. The cover is attached to the water-cooled wall so as to cover the outer portion of the heat transfer tube, which is the part of the heat transfer tube that is located on the outside in the direction of extension, and the opening. The heat transfer tube is supported in the fin at the lower edge of the opening. [Effects of the Invention]

[0008] According to one aspect of this disclosure, the manufacturing cost of a heat recovery boiler can be reduced. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic overall cross-sectional view of a heat recovery boiler in one embodiment of the present disclosure. [Figure 2] This is a cross-sectional view of the main part of a heat recovery boiler in one embodiment of the present disclosure. [Figure 3]This is a perspective view of the main part of a heat recovery boiler in one embodiment of the present disclosure. [Figure 4] This is a view from arrow IV in Figure 3. [Figure 5] Figure 3 is a cross-sectional view along the VV line. [Figure 6] This is an explanatory diagram showing the repair process of a heat transfer tube in one embodiment of the present disclosure. [Modes for carrying out the invention]

[0010] Hereinafter, embodiments of the heat recovery boiler of this disclosure will be described in detail with reference to the drawings.

[0011] As shown in Figure 1, the heat recovery boiler B in this embodiment is a boiler that generates steam by utilizing the heat of high-temperature exhaust gas G from, for example, a waste incinerator A. This heat recovery boiler B has a boiler casing 10 that defines a gas flow path P through which the high-temperature exhaust gas G flows, and a plurality of heat transfer tubes 40 arranged inside the boiler casing 10. Liquid or gaseous water flows inside the plurality of heat transfer tubes 40, and heat exchange occurs between this water and the exhaust gas G.

[0012] The boiler casing 10 includes a first path delimiting section 11 that extends vertically upward from the waste incinerator A and defines a first path P1 which is part of the gas flow path P; a second path delimiting section 12 that connects to the upper end of the first path P1 in another part of the gas flow path P and defines a second path P2 that extends vertically downward; and a third path delimiting section 13 that connects to the lower end of the second path P2 in yet another part of the gas flow path P and defines a third path P3 that extends vertically upward. The heat transfer tubes 40 are arranged inside the second path delimiting section 12 and the third path delimiting section 13.

[0013] As shown in Figure 2, the third path defining section 13 of the boiler casing 10 includes a water-cooled wall 20 that defines the third path P3, which is part of the gas flow path P, and a cover 30 located outside the water-cooled wall 20.

[0014] The multiple heat transfer tubes 40 arranged in this third path P3 have multiple straight pipe sections 41 that extend linearly in the pipe extension direction De which has a horizontal component, and folded sections 42 that connect the multiple straight pipe sections 41 to each other at the ends of the multiple straight pipe sections 41.

[0015] The heat recovery boiler B further includes a plurality of straight-tube connecting plates 29. The plurality of straight-tube connecting plates 29 are arranged within a third pass P3, which is part of the gas flow path P. Each of the plurality of straight-tube connecting plates 29 has a through hole through which a plurality of straight-tube sections 41 of each of the plurality of heat transfer tubes 40 pass. The straight-tube sections 41 are in contact with the inner circumferential surface of the through hole in the straight-tube connecting plate 29. As a result, the plurality of straight-tube sections 41 of each of the plurality of heat transfer tubes 40 are prevented from moving relative to each other in the vertical direction.

[0016] As shown in Figures 3 to 5, the water-cooled wall 20 has a plurality of water-cooled tubes 21 and a plurality of fins 22. Water can flow through the plurality of water-cooled tubes 21. The plurality of water-cooled tubes 21 extend in the vertical direction Dv and are spaced apart from each other, and are arranged horizontally along the edge of the third path P3, which is part of the gas flow path P. Hereafter, the direction perpendicular to the tube extension direction De in the horizontal direction will be referred to as the lateral direction Ds. The plurality of fins 22 are arranged between the plurality of water-cooled tubes 21. That is, each of the plurality of fins 22 is arranged between any two adjacent water-cooled tubes 21 in the lateral direction Ds. The plurality of fins 22 have a plurality of openings 23 that penetrate in the tube extension direction De.

[0017] The multiple fins 22 have multiple pipe support fins 22a and multiple closure fins 22b. The pipe support fins 22a have the lower edge of the opening 23. As shown in Figure 4, the pipe support fins 22a are connected to and fixed to one of the water cooling pipes 21 that are located adjacent to each other on both sides in the lateral direction Ds relative to the pipe support fins 22a, but are not connected to the other water cooling pipe 21. Therefore, there is a small gap between the pipe support fins 22a and the other water cooling pipe 21. The closure fins 22b are connected to each of the water cooling pipes 21 that are located adjacent to each other on both sides in the lateral direction Ds relative to the closure fins 22b, and close the gap between the two water cooling pipes 21.

[0018] Here, in the tube extension direction De, with the water wall 20 as a reference, the side of the gas flow path P is defined as the extension direction inner side Dei, and the opposite side is defined as the extension direction outer side Deo.

[0019] The heat transfer tube 40 extends from the extension direction inner side Dei, through the opening 23 of the fin 22, to the extension direction outer side Deo of the water wall 20. In the heat transfer tube 40, the portion arranged in the third pass P3 that is part of the gas flow path P is the aforementioned straight tube portion 41. Further, in the heat transfer tube 40, the portion extending to the extension direction outer side Deo of the water wall 20 is the aforementioned turn-back portion 42. For this reason, this turn-back portion 42 constitutes the heat transfer tube outer portion 43. The heat transfer tube 40 is supported in the fin 22 at the lower edge portion of the opening 23.

[0020] The cover 30 is disposed on the extension direction outer side Deo of the water wall 20, and is attached to the water wall 20 so as to cover the heat transfer tube outer portion 43 for each of the plurality of heat transfer tubes 40 and the plurality of openings 23. As shown in FIG. 5, the cover 30 includes a plurality of cover plates 31 forming the outer surface of the cover 30, a plurality of connectors 32 connecting the plurality of cover plates 31 to each other, and a heat insulating material 33 forming the inner surface of the cover 30. The connectors 32 in the present embodiment are, for example, bolts and nuts.

[0021] A support 25 is positioned at each of the multiple openings 23. The support 25 is positioned between the heat transfer tube 40, which penetrates the opening 23, and the lower edge of the opening 23. The support 25 has a sliding contact surface 26, a heat transfer tube contact surface 27, and a tube fixing portion 28. The sliding contact surface 26 is the surface that contacts the lower edge of the opening 23 so that the support 25 is movable relative to the tube support fin 22a. This sliding contact surface 26 is a plane that faces downward and extends in the lateral direction Ds and the tube extension direction De. The width of the sliding contact surface 26 in the tube extension direction De is wider than the thickness of the tube support fin 22a in the tube extension direction De. The heat transfer tube contact surface 27 is a semi-circular surface that matches the shape of the outer surface of the heat transfer tube 40. The heat transfer tube 40 is joined, for example, by spot welding to the outer surface of the heat transfer tube 40 and the edge of the semi-circular heat transfer tube contact surface 27 of the support 25. The joint between the heat transfer tube 40 and the support 25 is the tube fixing portion 28.

[0022] In this embodiment, the fins 22, which constitute a part of the water-cooled wall 20, support the heat transfer tubes 40. Therefore, in this embodiment, the number of components of the heat recovery boiler B can be reduced compared to the case where a separate support structure is provided, such as when a support structure for the heat transfer tubes 40 is placed in the gas flow path P. Moreover, in this embodiment, since the fins 22 are cooled by the water-cooled tubes 21 during the operation of the heat recovery boiler B, the temperature of the fins 22 is lower than the temperature of the central part of the gas flow path P. Therefore, the high-temperature durability of the fins 22 in this embodiment can be lower than the high-temperature durability of the support structure placed in the gas flow path P. In other words, the material cost of the fins 22 in this embodiment can be lower than the material cost of the support structure placed in the gas flow path P. Thus, in this embodiment, the manufacturing cost of the heat recovery boiler B can be reduced.

[0023] During the process in which the temperature of the exhaust gas G changes or the flow rate of the exhaust gas G changes, the heat transfer tube 40 expands or contracts due to thermal expansion and contraction, and moves relative to the water-cooled wall 20. In this embodiment, the heat transfer tube 40 does not come into contact with the fins 22, and the sliding contact surface 26 of the support 25 fixed to the heat transfer tube 40 comes into contact with the edge of the opening 23 of the fins 22. Therefore, in this embodiment, even if the heat transfer tube 40 moves relative to the water-cooled wall 20, damage to the fins 22 caused by this relative movement can be suppressed.

[0024] In this embodiment, the width of the sliding contact surface 26 in the pipe extension direction De is wider than the thickness of the fin 22 in the pipe extension direction De. Therefore, in this embodiment, even when the relative movement of the heat transfer tube 40 with respect to the water-cooled wall 20 in the pipe extension direction De becomes large, contact between the sliding contact surface 26 of the support 25 and the edge of the opening 23 of the fin 22 can be maintained.

[0025] In this embodiment, when inspecting or repairing the heat transfer tube 40, the connector 32 of the cover 30 is removed. In this embodiment, the cover 30 can be disassembled by removing the connector 32. Therefore, in this embodiment, the heat transfer tube 40, water cooling tube 21, fins 22, etc. inside the cover 30 can be easily inspected or repaired. It is preferable that the heat insulating material 33 is formed from the cover plate 31 to the vicinity of the folded portion 42 of the heat transfer tube 40. By keeping the space between the cover 30 and the folded portion 42 narrow, even if the fins 22 thin due to corrosion or the like and the opening 23 becomes larger, it is possible to prevent exhaust gas G from short-circuiting and escaping inside the cover 30.

[0026] In this embodiment, the pipe support fin 22a is connected to and fixed to one of the water cooling pipes 21 that are adjacent to the pipe support fin 22a on both sides in the lateral direction Ds, but is not connected to the other water cooling pipe 21. Therefore, in this embodiment, by cutting one of the water cooling pipes 21 at the upper and lower positions of the pipe support fin 22a, the cut portion of the water cooling pipe 21 can be rotated around the central axis C of the water cooling pipe 21. If damage to the heat transfer tube 40 is found, as shown in Figure 6, the water cooling pipe 21 is cut at the upper and lower positions of the pipe support fin 22a connected to the water cooling pipe 21, and the cut portion 21a of the water cooling pipe 21 is rotated, for example, 90° around the central axis C of the water cooling pipe 21. Due to this rotation, the pipe support fin 22a connected to the cut portion 21a of the water cooling pipe 21 also rotates 90° integrally with the cut portion 21a of the water cooling pipe 21. As a result, the opening 23 through which the damaged heat transfer tube 40 passes widens in the vertical direction Dv. Therefore, in this embodiment, the damaged portion of the heat transfer tube 40 can be easily removed or repaired.

[0027] "Variations" In the above embodiment, exhaust gas G flows into the heat recovery boiler B from the waste incinerator A. However, the exhaust gas G flowing into the heat recovery boiler B does not have to be exhaust gas G from the waste incinerator A, as long as it is a high-temperature exhaust gas G capable of generating steam. For example, it may be exhaust gas G from a gasification melting furnace or the like.

[0028] In the above embodiment, the heat recovery boiler B is a boiler with a 3-pass exhaust gas flow path. However, the heat recovery boiler B may also be a boiler with a 1-pass or 2-pass exhaust gas flow path, or a boiler with 4 or more passes.

[0029] The heat recovery boiler B in the above embodiment has a characteristic structure in the third pass delimiter 13. However, other pass delimiters may also have characteristic structures.

[0030] The heat recovery boiler B in the above embodiment has a support 25. However, this support 25 is not required. However, it is preferable to provide the support 25 from the viewpoint of suppressing damage to the fins 22. It is preferable that the maximum width of the support 25 in the lateral direction Ds is greater than the outer diameter of the heat transfer tube 40. By having the maximum width of the support 25 in the lateral direction Ds greater than the outer diameter of the heat transfer tube 40, the possibility of the heat transfer tube 40 coming into contact with the water cooling tube 21 can be reduced.

[0031] In the above embodiment, the pipe support fin 22a is connected to and fixed to one of the water cooling pipes 21 that are adjacent to the pipe support fin 22a on both sides in the lateral direction Ds, but is not connected to the other water cooling pipe 21. However, the pipe support fin 22a may be connected to and fixed to one of the water cooling pipes 21 that are adjacent to the pipe support fin 22a on both sides in the lateral direction Ds, and also connected to and fixed to the other water cooling pipe 21. In this case, since no gap is formed between the pipe support fin 22a and one water cooling pipe 21, and between the pipe support fin 22a and the other water cooling pipe 21, the flow rate of exhaust gas G in the gas flow path P into the cover 30 can be reduced. However, in this case, the repairability of the heat transfer tube 40 deteriorates.

[0032] In the above embodiment, the heat recovery boiler B is provided with a plurality of straight-tube connecting plates 29. However, these straight-tube connecting plates 29 are not required. However, it is preferable to provide the straight-tube connecting plates 29 from the viewpoint of suppressing the relative vertical movement of the straight-tube sections 41 of the heat transfer tubes 40.

[0033] This disclosure is not limited to the embodiments described above. Various additions, modifications, substitutions, partial deletions, etc., are possible without departing from the conceptual idea and spirit of the present invention derived from the claims and their equivalents.

[0034] "Addendum" The heat recovery boiler B in the above embodiments can be understood, for example, as follows.

[0035] (1) The heat recovery boiler B in the first embodiment is The boiler casing 10 covering the heat transfer tubes 40 comprises a water-cooled wall 20 that is arranged around a gas passage P extending in the vertical direction Dv through which exhaust gas G can flow and defines the gas passage P; a heat transfer tube 40 through which water can flow and which extends in the pipe extension direction De having a horizontal component, and which exchanges heat between the water and the exhaust gas G flowing in the gas passage P; and a cover 30 located in the pipe extension direction De, on the outer side of the extension direction Deo, which is on the side of the gas passage P with respect to the water-cooled wall 20, and the inner side of the extension direction Deo which is on the opposite side of the inner side of the extension direction Dei. The boiler casing 10 covering the heat transfer tubes 40 is composed of the water-cooled wall 20 and the cover 30. The water-cooled wall 20 has a plurality of water-cooled tubes 21 that extend in the vertical direction Dv, are spaced apart from each other and arranged horizontally along the edge of the gas passage P, and fins 22 arranged between the plurality of water-cooled tubes 21. The fin 22 is fixed to at least one of the water-cooling tubes 21 that are adjacent to each other on both sides of the lateral direction Ds, perpendicular to the tube extending direction De and where a plurality of water-cooling tubes 21 are lined up, with respect to the fin 22. The fin 22 has an opening 23 that penetrates in the tube extending direction De. The heat transfer tube 40 extends from the inner side Dei in the extending direction, through the opening 23 of the fin 22, to the outer side Deo in the extending direction. The cover 30 is attached to the water-cooling wall 20 so as to cover the outer portion 43 of the heat transfer tube 40, which is the portion located in the outer side Deo in the extending direction, and the opening 23. The heat transfer tube 40 is supported in the fin 22 at the lower edge portion of the opening 23.

[0036] In this embodiment, the fins 22, which constitute a part of the water-cooled wall 20, support the heat transfer tubes 40. Therefore, in this embodiment, the number of components of the heat recovery boiler B can be reduced compared to the case where a separate support structure is provided, such as when a support structure for the heat transfer tubes 40 is placed within the gas flow path P. Moreover, in this embodiment, since the fins 22 are cooled by the water-cooled tubes 21 during the operation of the heat recovery boiler B, the temperature of the fins 22 is lower than the temperature of the central part of the gas flow path P. Therefore, the high-temperature durability of the fins 22 in this embodiment can be lower than the high-temperature durability of the support structure placed within the gas flow path P. In other words, the material cost of the fins 22 in this embodiment can be lower than the material cost of the support structure placed within the gas flow path P. Thus, in this embodiment, the manufacturing cost of the heat recovery boiler B can be reduced.

[0037] (2) The heat recovery boiler B in the second embodiment is The heat recovery boiler B in the first embodiment is provided with a support 25 positioned in the opening 23. The support 25 has a sliding contact surface 26 that contacts the lower edge of the opening 23 so as to be movable relative to the fins 22, and a pipe fixing portion 28 that is fixed to the heat transfer tube 40.

[0038] During the process in which the temperature of the exhaust gas G changes or the flow rate of the exhaust gas G changes, the heat transfer tube 40 expands or contracts due to thermal expansion or contraction and moves relative to the water-cooled wall 20. In this embodiment, the heat transfer tube 40 does not come into contact with the fins 22, and the sliding contact surface 26 of the support 25 fixed to the heat transfer tube 40 comes into contact with the edge of the opening 23 of the fins 22. Therefore, in this embodiment, even if the heat transfer tube 40 moves relative to the water-cooled wall 20, damage to the fins 22 caused by this relative movement can be suppressed.

[0039] (3) The heat recovery boiler B in the third embodiment is In the heat recovery boiler B of the second embodiment described above, the width of the sliding contact surface 26 in the pipe extension direction De is wider than the thickness of the fin 22 in the pipe extension direction De.

[0040] In this embodiment, even when the relative movement of the heat transfer tube 40 with respect to the water-cooled wall 20 in the tube extension direction De becomes large, contact between the sliding surface 26 of the support 25 and the edge of the opening 23 of the fin 22 can be maintained.

[0041] (4) The heat recovery boiler B in the fourth embodiment is In the heat recovery boiler B according to any one of the first to third embodiments described above, the fin 22 is connected to one of the water cooling tubes 21 that are adjacent to each other on both sides in the lateral direction Ds with respect to the fin 22, but is not connected to the other water cooling tube 21.

[0042] In this embodiment, the fin 22 is connected to one water cooling tube 21 but not to the other water cooling tube 21. Therefore, in this embodiment, by cutting one water cooling tube 21 at both the upper and lower positions of the fin 22 to which one water cooling tube 21 is connected, the cut portion of the water cooling tube 21 can be rotated around the central axis C of the water cooling tube 21. If damage to the heat transfer tube 40 is found, as described above, one water cooling tube 21 is cut at both the upper and lower positions of the fin 22 to which one water cooling tube 21 is connected, and the cut portion 21a of the water cooling tube 21 is rotated, for example, 90° around the central axis C of the water cooling tube 21. Due to this rotation, the fin 22 connected to the cut portion 21a of the water cooling tube 21 also rotates 90° integrally with the cut portion 21a of the water cooling tube 21. As a result, the opening 23 through which the damaged heat transfer tube 40 passes widens in the vertical direction Dv. Therefore, in this embodiment, the damaged portion of the damaged heat transfer tube 40 can be easily removed or repaired.

[0043] (5) The heat recovery boiler B in the fifth embodiment is In the heat recovery boiler B according to any one of the first to fourth embodiments described above, the cover 30 has a plurality of cover plates 31 and a plurality of connectors 32 that connect the plurality of cover plates 31 to each other.

[0044] In this embodiment, the cover 30 can be disassembled by removing the connector 32. Therefore, in this embodiment, the heat transfer tubes 40, water cooling tubes 21, fins 22, etc. inside the cover 30 can be easily inspected or repaired.

[0045] (6) The heat recovery boiler B in the sixth embodiment is In the heat recovery boiler B according to any one of the first to fifth embodiments described above, the heat transfer tube 40 has a plurality of straight tube sections 41 that extend linearly in the direction De of the tube extension within the gas flow path P, and a folded portion 42 that connects the plurality of straight tube sections 41 to each other at the ends of the plurality of straight tube sections 41. The folded portion 42 is the outer portion 43 of the heat transfer tube.

[0046] (7) The heat recovery boiler B in the seventh embodiment is In the heat recovery boiler B of the sixth embodiment, a straight pipe connecting plate 29 is provided, which is arranged in the gas flow path P and is in contact with each of the plurality of straight pipe sections 41, thereby suppressing the relative movement of the plurality of straight pipe sections 41 in the vertical direction Dv. [Explanation of Symbols]

[0047] A: Garbage incinerator B: Heat recovery boiler G: Exhaust gas P: Gas flow path P1: First Pass P2: Second Pass P3: Third Pass 10: Boiler casing 11: First path drawing section 12: Second path drawing section 13: Third path drawing section 20:Water cooling wall 21: Water cooling pipe 21a: Water cooling pipe section 22: Finn 22a: Pipe support fins 22b: Occlusion fin 23:Aperture 25: Support 26: Sliding surface 27: Heat transfer tube contact surface 28: Pipe fixing part 29: Straight pipe connection plate 30: Cover 31: Cover plate 32: Connector 33: Heat insulating material 40: Heat transfer tube 41: Straight pipe portion 42: Turnback portion 43: Heat transfer tube outer portion C: Central axis De: Tube extending direction Dei: Extending direction inner side Deo: Extending direction outer side Ds: Lateral direction Dv: Vertical direction

Claims

1. A water-cooled wall is arranged around a gas passage that extends vertically and through which exhaust gas can flow, and which defines the gas passage. A heat transfer tube through which water can flow, extending in the direction of the tube having a horizontal component, and exchanging heat between the water and the exhaust gas flowing in the gas passage, In the direction of extension of the pipe, with reference to the water-cooled wall, the cover is located on the outer side of the extension direction, which is the side of the gas flow path and the inner side of the extension direction, and the opposite side of the inner side of the extension direction. Equipped with, The boiler casing covering the heat transfer tubes is configured to have the water-cooled wall and the cover, The water-cooled wall has a plurality of water-cooling tubes that extend vertically, are spaced apart from each other and arranged horizontally along the edge of the gas flow path, and fins arranged between the plurality of water-cooling tubes. The fin is fixed to at least one of the water cooling tubes that are adjacent to each of the water cooling tubes arranged on each side in the lateral direction perpendicular to the extension direction of the tube and with respect to the fin, The fin has an opening that penetrates in the direction of the extension of the pipe. The heat transfer tube extends from the inside in the direction of extension, through the opening of the fin, to the outside in the direction of extension. The cover is attached to the water-cooled wall so as to cover the outer portion of the heat transfer tube, which is the portion located on the outer side in the direction of extension of the heat transfer tube, and the opening. The heat transfer tube is supported in the fin at the lower edge of the opening. Heat recovery boiler.

2. In the heat recovery boiler according to claim 1, The opening is provided with a support, The support comprises a sliding contact surface that contacts the lower edge of the opening so as to be movable relative to the fin, and a tube fixing portion that is fixed to the heat transfer tube. Heat recovery boiler.

3. In the heat recovery boiler according to claim 2, The width of the sliding contact surface in the direction of pipe extension is wider than the thickness of the fin in the direction of pipe extension. Heat recovery boiler.

4. In a heat recovery boiler according to any one of claims 1 to 3, The fin is connected to one of the water cooling pipes, which are arranged adjacent to each of the water cooling pipes on both sides in the lateral direction relative to the fin, but is not connected to the other water cooling pipe. Heat recovery boiler.

5. In a heat recovery boiler according to any one of claims 1 to 3, The cover comprises a plurality of cover plates and a plurality of connectors that connect the plurality of cover plates to each other. Heat recovery boiler.

6. In a heat recovery boiler according to any one of claims 1 to 3, The heat transfer tube has a plurality of straight sections extending linearly in the direction of the tube's extension within the gas flow path, and folded sections connecting the plurality of straight sections at their ends. The aforementioned folded portion is the outer portion of the heat transfer tube. Heat recovery boiler.

7. In the heat recovery boiler according to claim 6, The gas flow path is provided with a straight pipe connecting plate that is in contact with each of the multiple straight pipe sections and suppresses the relative vertical movement of the multiple straight pipe sections. Heat recovery boiler.

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