JP2017089909A - Economizer, boiler, and repair method of heat exchanger tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the workability of repair operations of heat exchanger tubes in an economizer, a boiler, and a repair method of heat exchanger tube.SOLUTION: An economizer comprises: a first economizer 47 in which a plurality of waveform-shaped first heat exchanger tubes 101 are juxtaposed in a horizontal direction at predetermined intervals; an inlet header 65 connected to a vertical lower end part of the plurality of first heat exchanger tubes 101; a second economizer 46 which is disposed vertically above the first economizer 47 and in which a plurality of second heat exchanger tubes 102 along the vertical direction are juxtaposed in the horizontal direction at predetermined intervals; an outlet header 68 connected to a vertical upper end part of the plurality of second heat exchanger tubes 102; and an intermediate header 67 which can be connected to a vertical upper end part of the plurality of first all heat exchanger tubes 101 as well as connected to a vertical lower end part of the plurality of second all heat exchanger tubes 102. The first economizer 47 and the second economizer 46 are individually managed via the intermediate header 67.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a economizer provided in a boiler for generating steam, a boiler provided with the economizer, and a heat transfer pipe repair method.

  A large-sized boiler such as a conventional coal-fired boiler has a furnace that has a hollow shape and is installed in a vertical direction, and a plurality of combustion burners are arranged on the furnace wall along the circumferential direction. The coal fired boiler is connected to a flue vertically above the furnace, and a heat exchanger for generating steam is disposed in the flue. Therefore, a flame is formed when the combustion burner injects a mixture of fuel and air into the furnace, and combustion gas is generated and flows into the flue. Then, steam is generated by heating the boiler feed water flowing through the heat exchanger with the combustion gas generated by the combustion.

  In such a coal fired boiler, the heat exchanger arranged in the flue is composed of a superheater, a reheater, and a economizer. The boiler feedwater supplied from the feedwater pump to the heat exchanger is preheated by the economizer, then heated while being supplied to the water pipe on the furnace wall, becomes saturated steam, and is superheated by the combustion gas in the superheater. The superheated steam generated by the superheater is supplied to the high-pressure steam turbine and used for rotational driving. The steam after the rotational driving is reheated by the reheater and supplied to the low-pressure steam turbine for rotational driving. In addition, there exists a thing described in the following patent document 1 as a boiler provided with such a heat exchanger.

Japanese Patent Laid-Open No. 03-117801

  By the way, when the heat transfer tube used in a coal-fired boiler economizer that burns coal as fuel is used over a long period of time, solid ash (fly ash) generated by the combustion of coal flows through the flue along with the combustion gas, The solid ash collides with the heat transfer tube of a heat exchanger such as a superheater or a economizer installed in the flue and wears the surface of the heat transfer tube. Leakage of boiler feed water may occur due to wear due to coal solid ash contained in the combustion gas, corrosion due to boiler feed water that circulates inside the heat transfer tube, and the like. Conventionally, when a boiler feedwater leak occurs in a heat transfer tube, the operation of the boiler must be stopped, and the heat transfer tube in which the boiler feedwater leak occurs must be closed or replaced with a healthy one. In this case, the economizer needs to block the entire heat transfer tube where the boiler feedwater leaks or replace the entire heat transfer tube with a healthy one. There is a problem that it takes a long time. In addition, Patent Document 1 below describes a heat exchanger in which an intermediate header is provided between two divided heat transfer tubes. However, in Patent Document 1, two divided heat transfer tubes are adjacent to each other in the horizontal direction. It is difficult to apply to a combustion gas passage where combustion gas flows from the upper part to the lower part.

  This invention solves the subject mentioned above, and it aims at providing the repair method of the economizer and boiler which aim at the workability | operativity improvement in the repair work of a heat exchanger tube, and a heat exchanger tube.

  In order to achieve the above object, a economizer of the present invention is a economizer provided in a combustion gas passage through which combustion gas flows from the upper part to the lower part in the vertical direction, and a plurality of first heat transfer tubes having a corrugated shape. Are arranged in a horizontal direction at a predetermined interval, an inlet header connected to a lower end portion in a vertical direction of the plurality of first heat transfer tubes, and a vertical direction from the first economizer. A plurality of second heat transfer tubes arranged in the vertical direction and arranged in parallel in the horizontal direction at predetermined intervals, and a vertical upper end portion of the plurality of second heat transfer tubes It is possible to connect to the outlet header to be connected to the upper end portions in the vertical direction of all the plurality of first heat transfer tubes, and to be connected to the lower end portions in the vertical direction of all of the plurality of second heat transfer tubes. An intermediate header, wherein the first economizer and the second economizer Vessel A, through said intermediate header is managed separately, it is characterized in.

  Therefore, the 2nd economizer which consists of a plurality of 2nd heat exchanger tubes which follow the perpendicular direction is arranged above the 1st economizer which consists of a plurality of 1st heat exchanger tubes which make a waveform shape, and the upper end of each 1st heat exchanger tube An intermediate header is connected between the first heat transfer tube and the lower end of each second heat transfer tube, and the first and second economizers are individually managed via the intermediate header, The second heat transfer tube can function independently. For example, when a leak point occurs in a part of the first heat transfer tube, it is not necessary to close the second heat transfer tube by simply closing the inlet header and the intermediate header tube in the first heat transfer tube. The heat transfer tube can be repaired at an early stage, and the workability in the heat transfer tube repair work can be improved.

  In the economizer of the present invention, the second heat transfer tube has an upper portion in the vertical direction penetrating the support beam and is prevented from moving downward in the vertical direction with respect to the support beam by a locking member, and the intermediate header is provided at the lower end portion. It is connected and supported by suspension.

  Therefore, since the intermediate header is suspended and supported by the support beam via the second heat transfer tube, a hanging tool for supporting the intermediate header is not necessary, and the structure can be prevented from becoming complicated.

  In the economizer of the present invention, the first heat transfer tube is suspended and supported by the intermediate header by a lifting tool, and an upper end portion is connected to the intermediate header.

  Accordingly, the first heat transfer tube is connected to the intermediate header in a state of being supported by being suspended from the intermediate header by the hanger, so that a hanger for supporting the first heat transfer tube becomes unnecessary, and the first heat transfer tube And the intermediate header can be easily connected, and the complexity of the structure can be suppressed.

  In the economizer of the present invention, the intermediate header is disposed in the combustion gas passage.

  Therefore, by arranging the intermediate header in the combustion gas passage, the first heat transfer tube, the intermediate header, and the second heat transfer tube can be easily connected, and the structure can be simplified.

  In the economizer of the present invention, the intermediate header is provided along a parallel direction of the plurality of first heat transfer tubes and the plurality of second heat transfer tubes, and the plurality of first heat transfer tubes and the plurality of the plurality of first heat transfer tubes. A plurality of the heat transfer tubes are arranged in parallel in a horizontal direction perpendicular to the direction in which the second heat transfer tubes are arranged.

  Therefore, a plurality of first intermediate heat transfer tubes, a plurality of intermediate headers, and a plurality of second heat transfer tubes are connected by arranging a plurality of intermediate headers along the horizontal direction at predetermined intervals. By shortening the length, the structure can be simplified and the cost can be reduced.

  The economizer of the present invention is characterized in that the number of the plurality of first heat transfer tubes is greater than the number of the plurality of second heat transfer tubes.

  Therefore, the number of the first heat transfer tubes can be provided by the intermediate header more than the number of the second heat transfer tubes, the degree of design freedom can be expanded, and the number of the first heat transfer tubes in the low temperature region can be increased. The heat exchange efficiency can be improved.

  In the economizer of the present invention, the plurality of second heat transfer tubes are provided with a support portion that supports a heat transfer tube of another heat exchanger.

  Therefore, by providing a support portion for supporting the heat transfer tube of another heat exchanger in the second heat transfer tube, a support member for supporting the heat transfer tube of another heat exchanger is not required, and the complexity of the structure is suppressed. can do.

  In the economizer of the present invention, the nozzle of the intermediate header to which one end portions of the plurality of first heat transfer tubes having a leakage portion are connected and the other end portion of the first heat transfer tube having the leakage portion are connected. The nozzle of the inlet header is closed.

  Therefore, the boiler can be continuously used without impairing the function of the second economizer by closing the nozzle of the intermediate header and the nozzle of the inlet header in the first heat transfer tube having the leakage portion. .

  The economizer of the present invention is characterized in that the length of the nozzle pedestal remaining on the intermediate header by cutting the first heat transfer tube having the leakage portion is in the range of 5 mm to 25 mm.

  If the length of the nozzle head remaining in the intermediate header exceeds 25 mm, the temperature of the nozzle rises due to the exhaust gas temperature in the vicinity and the strength decreases. If the length is less than 5 mm, the cutting work, the closing work and the reconnection welding work are performed. Workability becomes difficult. Therefore, by setting the length of the nozzle stub remaining in the intermediate header within this range, the nozzle is soundly blocked and can be repaired.

  Further, the boiler of the present invention has a hollow furnace that is installed along the vertical direction, a combustion device that is disposed in the furnace, a flue that is connected to the upper part of the furnace and flows combustion gas, A heat exchanger disposed in the flue, wherein the economizer is provided as one of the heat exchangers.

  Therefore, the upper end part of each 1st heat exchanger tube of the 1st economizer arrange | positioned below and the lower end part of each 2nd heat exchanger tube of the 2nd economizer arranged above are connected by the intermediate header. By configuring the economizer, the first heat transfer tube and the second heat transfer tube can function independently. For example, when a leak point occurs in a part of the first heat transfer tube, it is not necessary to close the second heat transfer tube by simply closing the inlet header and the intermediate header tube in the first heat transfer tube. The heat transfer tube can be repaired at an early stage, and the workability in the heat transfer tube repair work can be improved.

  In the boiler according to the present invention, a superheater or a reheater is provided as one of the heat exchangers, and a heat transfer tube of the superheater or the reheater is supported by the second heat transfer tube. .

  Therefore, by supporting the heat transfer tube of the superheater or the reheater with the second heat transfer tube, a support member for supporting the heat transfer tube of the superheater or the reheater becomes unnecessary, and the complexity of the structure is suppressed. Can do.

  Further, the heat transfer tube repair method of the present invention is a heat transfer tube repair method in a economizer, and is provided in a combustion gas passage in which the combustion gas flows from the upper part to the lower part in the vertical direction and has a plurality of corrugated shapes. A first economizer in which one heat transfer tube is arranged in a horizontal direction at a predetermined interval; an inlet header connected to a lower end portion in a vertical direction of the plurality of first heat transfer tubes; and the first economizer A plurality of second heat transfer tubes that are arranged above the vertical direction and have a plurality of second heat transfer tubes along the vertical direction arranged in parallel in a horizontal direction, and a vertical direction in the plurality of second heat transfer tubes; An outlet header connected to the upper end, and a lower end of the plurality of second heat transfer tubes in the vertical direction that can be connected to the upper end of the plurality of first heat transfer tubes in the vertical direction. An intermediate header coupled to the first charcoal And the second economizer are individually managed via the intermediate header, and the nozzle of the intermediate header to which the first heat transfer pipe having the leaking portion is connected is cut leaving a predetermined length. Cutting the nozzle of the inlet header to which the first heat transfer tube having the leakage portion is connected, leaving a predetermined length, and closing the nozzle of the cut intermediate header; And a step of closing the cut nozzle of the inlet header.

  Therefore, for example, when a leak location occurs in a part of the first heat transfer tube, it is necessary to close the second heat transfer tube by simply closing the inlet header and the intermediate header in the first heat transfer tube. However, early repair of the heat transfer tube is possible, and workability in the heat transfer tube repair work can be improved.

  According to the economizer, the boiler, and the heat transfer tube repair method of the present invention, the second heat transfer tube including the plurality of second heat transfer tubes along the vertical direction on the upper side in the vertical direction of the first economizer including the plurality of first heat transfer tubes. Since the two economizers are arranged and the intermediate header is connected between the vertical upper end of each first heat transfer tube and the vertical lower end of each second heat transfer tube, the first heat transfer tube and the second heat transfer tube Can be made to function independently, workability in the heat transfer tube repair work can be improved, and the operating rate of the boiler can be improved.

FIG. 1 is a schematic configuration diagram illustrating a coal fired boiler according to the present embodiment. FIG. 2 is a schematic diagram showing a heat exchanger provided in a coal fired boiler. FIG. 3 is a side view showing the economizer of the present embodiment. FIG. 4 is a front view illustrating the economizer of the present embodiment. FIG. 5 is a perspective view showing a connecting portion between the support beam and the second economizer. FIG. 6 is a perspective view showing the first economizer and the intermediate header. FIG. 7 is a schematic diagram showing a heat transfer tube repair method in a economizer. FIG. 8 is a schematic diagram showing a heat transfer tube repair method in a economizer. FIG. 9 is a cross-sectional view illustrating a method for closing a nozzle for a heat transfer tube. FIG. 10 is a cross-sectional view illustrating a method for closing a nozzle for a heat transfer tube. FIG. 11 is a cross-sectional view illustrating a method for closing a nozzle for a heat transfer tube. FIG. 12 is a cross-sectional view illustrating another method for closing the nozzle for heat transfer tubes.

  Exemplary embodiments of a economizer, a boiler, and a heat transfer tube repair method according to the present invention will be described below in detail with reference to the accompanying drawings. In addition, this invention is not limited by this embodiment, and when there are two or more embodiments, what comprises combining each embodiment is also included.

  FIG. 1 is a schematic configuration diagram illustrating a coal fired boiler according to the present embodiment.

  The boiler of this embodiment uses pulverized coal obtained by pulverizing coal as pulverized fuel (solid fuel), burns the pulverized coal with a combustion burner, and recovers the heat generated by the combustion. It is.

  In the present embodiment, as shown in FIG. 1, the coal fired boiler 10 is a conventional boiler, and includes a furnace 11, a combustion device 12, and a flue 13. The furnace 11 has a rectangular hollow shape and is installed along the vertical direction. The furnace wall constituting the furnace 11 is constituted by a heat transfer tube. 1 and 6, the left side of the drawing shows the vertical upward direction, and in FIGS. 2 to 5, 8, and 9, the upward direction of the drawing shows the vertical upward direction. In the following description, “upper” and “upper” indicate the upper side in the vertical direction, and “lower” and “lower” indicate the lower side in the vertical direction.

  The combustion device 12 is provided in a lower part of a furnace wall (heat transfer tube) constituting the furnace 11. This combustion apparatus 12 has a plurality of combustion burners 21, 22, 23, 24, 25 mounted on the furnace wall. In this embodiment, the combustion burners 21, 22, 23, 24, and 25 are arranged as four sets at equal intervals along the circumferential direction, and five sets along the vertical direction. Five stages are arranged. However, the shape of the furnace, the number of combustion burners in one stage, and the number of stages are not limited to this embodiment.

  The combustion burners 21, 22, 23, 24, 25 are fed to pulverizers (pulverized coal machines / mills) 31, 32, 33, 34, 35 via pulverized coal supply pipes 26, 27, 28, 29, 30. It is connected. Therefore, when coal is put into the pulverizers 31, 32, 33, 34, and 35, the pulverized coal pulverized to a predetermined size and classified by the conveying air (primary air) is supplied to the pulverized coal supply pipe 26. , 27, 28, 29, 30 can be supplied to the combustion burners 21, 22, 23, 24, 25.

  The flue 13 is connected to the upper part of the furnace 11. This flue 13 is used as a heat exchanger for recovering the heat of the combustion gas, such as superheaters (superheaters) 41, 42, 43, reheaters (reheaters) 44, 45, economizers 46, 47 is provided, and heat exchange is performed between the combustion gas generated by the combustion in the furnace 11 and water.

  The flue 13 is connected to a gas duct 48 through which the combustion gas that has exchanged heat is discharged downstream. This gas duct 48 is provided with an air heater 49 between the air duct 37 and performs heat exchange between the air flowing through the air duct 37 and the combustion gas flowing through the gas duct 48, and the combustion burners 21, 22, 23, 24. , 25 can raise the temperature of combustion air.

  The flue 13 is provided with a selective reduction catalyst (denitration catalyst) 50 at a position upstream of the air heater 49. The selective catalytic reduction catalyst 50 supplies a reducing agent having an action of reducing nitrogen oxides such as ammonia and urea water into the flue 13, and the combustion gas supplied with the reducing agent is mixed with the nitrogen oxides and the reducing agent. By promoting the reaction, nitrogen oxides in the combustion gas are removed and reduced. The gas duct 48 connected to the flue 13 is provided with a dust treatment device (electric dust collector, desulfurization device) 51 and an induction blower 52 at a position downstream of the air heater 49, and with a chimney 53 at the downstream end. Yes.

  Therefore, when the pulverizers 31, 32, 33, 34, and 35 are driven, the generated pulverized coal together with the carrier air passes through the pulverized coal supply pipes 26, 27, 28, 29, 30 and the combustion burners 21, 22, 23, 24. , 25. Also, heated combustion air is supplied from the air duct 37 to the combustion burners 21, 22, 23, 24, 25 via the wind box 36. Then, the combustion burners 21, 22, 23, 24, and 25 blow the pulverized fuel mixture mixed with the pulverized coal and the carrier air into the furnace 11 and blow the combustion air into the furnace 11 and ignite at this time. Can form a flame. In the furnace 11, in the region A, the pulverized fuel mixture and the combustion air are burned to generate a flame. When a flame is generated in the lower part of the furnace 11, a combustion gas (hereinafter referred to as exhaust gas) is generated. The furnace 11 rises and is discharged to the flue 13.

  Thereafter, the exhaust gas is heat-exchanged by the superheaters 41, 42, 43, the reheaters 44, 45, and the economizers 46, 47 arranged in the flue 13, and then the nitrogen oxides are reduced by the selective reduction catalyst 50. After being removed and the particulate matter removed by the dust treatment device 51 and the sulfur content removed, it is discharged from the chimney 53 to the atmosphere.

  Here, the superheaters 41, 42, 43, the reheaters 44, 45, and the economizers 46, 47 provided in the flue 13 will be described in detail as heat exchangers. FIG. 2 is a schematic diagram showing a heat exchanger provided in a coal fired boiler.

  In the present embodiment, as shown in FIG. 2, the flue 13 is provided with a combustion gas passage 60 therein, and in the combustion gas passage 60, superheaters 41, 42, 43, reheaters 44, 45, The economizers 46 and 47 are arranged. In addition, since the superheaters 41, 42, and 43 are provided in series via a header, this header is omitted in FIG.

  A steam turbine 61 that is operated by steam generated in the coal-fired boiler 10 includes, for example, a high-pressure turbine 62 and a low-pressure turbine 63. A condenser 64 is connected to the low-pressure turbine 63, and the steam that rotationally drives the low-pressure turbine 63 is cooled by cooling water (for example, seawater) in the condenser 64 to become condensed water. The condenser 64 is connected to the inlet header 65 of the first economizer 47 through the water supply line L1. The inlet header 65 is provided in the combustion gas passage 60, and the water supply line L <b> 1 is provided with a water supply pump 66 outside the combustion gas passage 60. The second economizer 46 is disposed vertically above the first economizer 47, and an intermediate header 67 is provided between the economizers 46 and 47. The second economizer 46 has an outlet header 68 connected to the top thereof, and the outlet header 68 is disposed outside the combustion gas passage 60.

  The outlet header 68 is connected to a steam drum 69 disposed outside the combustion gas passage 60 via a water supply line L2. The steam drum 69 is connected to each heat transfer tube (not shown) on the furnace wall, and is connected to superheaters 41, 42, and 43. The superheaters 41, 42, and 43 are high-pressure via a steam line L3. The turbine 62 is connected. And the steam which rotationally driven the high pressure turbine 62 is connected with the inlet header 70 of the 1st reheater 45 via the steam line L4. The inlet header 70 is provided in the combustion gas passage 60, the first reheater 45 is connected to the second reheater 44 via the intermediate header 71, and the second reheater 44 is connected to the upper outlet. A header 72 is connected, and the intermediate header 71 and the outlet header 72 are disposed outside the combustion gas passage 60. The outlet header 72 is connected to the low-pressure turbine 63 via the steam line L5 and rotationally drives the low-pressure turbine 63.

  Therefore, when the exhaust gas flows through the combustion gas passage 60 of the flue 13, the exhaust gas is heat recovered in the order of the superheaters 41, 42, 43, the reheaters 44, 45, and the economizers 46, 47. On the other hand, the boiler feed water supplied from the feed water pump 66 is preheated by the economizers 47 and 46, then supplied to the steam drum 69, and heated and saturated while being supplied to each heat transfer tube on the furnace wall (not shown). Steam is returned to the steam drum 69. The saturated steam of the steam drum 69 is introduced into the superheaters 41, 42, 43 and is superheated by the exhaust gas. The superheated steam generated by the superheaters 41, 42, 43 is supplied to the high pressure turbine 62 and rotationally drives the high pressure turbine 62. The steam discharged from the high-pressure turbine 62 is introduced into the reheaters 45 and 44 and heated again, and then supplied to the low-pressure turbine 63 to drive the low-pressure turbine 63. The steam discharged from the low-pressure turbine 63 is cooled by the condenser 64 to become condensed water, and is sent to the economizers 47 and 46 again.

  Hereinafter, the economizer of this embodiment will be described in detail. FIG. 3 is a side view showing the economizer of the present embodiment, FIG. 4 is a front view showing the economizer of the present embodiment, and FIG. 5 shows a connecting portion between the support beam and the second economizer. FIG. 6 is a perspective view showing a first economizer and an intermediate header. 3 and 4, the heat transfer tube 103 of the first reheater 45 is omitted.

  The economizer of this embodiment is comprised from the 1st economizer 47 and the 2nd economizer 46 which were arrange | positioned along the vertical direction within the combustion gas channel | path 60, as shown in FIG.3 and FIG.4. The first economizer 47 is disposed below the second economizer 46. The first economizer 47 is configured by arranging a plurality of first heat transfer tubes 101 having a waveform shape in parallel in the horizontal direction with a predetermined interval therebetween. The second charcoal portion 46 is configured by arranging a plurality of second heat transfer tubes 102 along the vertical direction in parallel in the horizontal direction with a predetermined interval. The lower ends of the plurality of first heat transfer tubes 101 are connected to the inlet header 65, and the upper ends of the plurality of second heat transfer tubes 102 are connected to the outlet header 68. The upper ends of the plurality of first heat transfer tubes 101 are connected to the intermediate header 67, and the lower ends of the plurality of second heat transfer tubes 102 are connected to the intermediate header 67.

Here, all the plurality of first heat transfer tubes 101 of the first economizer 47 can be connected to the intermediate header 67. For this reason, it is possible to equalize the boiler feed water flowing into the plurality of first heat transfer tubes 101, which is preferable in order to equalize the heat transfer performance of the plurality of first heat transfer tubes 101.
Moreover, since the 1st economizer and the 2nd economizer 46 can be managed individually via the intermediate header 67, the design freedom can be expanded and the operation becomes easy.

  In the flue 13 (see FIG. 1), a plurality of upper support beams 111 extending in the horizontal direction are arranged on the upper portion at a predetermined interval, and each upper support beam 111 has a plurality of support beams along a vertical direction (not shown). Is supported by In each upper support beam 111, a plurality of lower support beams 113 are suspended and supported by a plurality of suspension bars 112. Each lower support beam 113 is positioned below each upper support beam 111 and is arranged at a predetermined interval in the horizontal direction. Further, as will be described later (FIG. 6), a plurality of first heat transfer tubes 101 bent into the corrugated shape of the first economizer 47 are bundled by a support 117 and supported by being suspended from an intermediate header 67 by a suspension 116. Has been.

  As shown in detail in FIG. 5, the plurality of second heat transfer tubes 102 of the second economizer 46 pass through the lower support beam 113 in the vertical direction, and a pair of second heat transfer tubes 102 on the upper side of the penetrated second heat transfer tube 102. Since the locking piece (locking member) 114 is fixed, the second heat transfer tube 102 is prevented from moving vertically downward relative to the lower support beam 113 by the locking piece 114. That is, the second heat transfer tube 102 is suspended and supported by the lower support beam 113 via the locking piece 114. The plurality of second heat transfer tubes 102 are gathered by bending the upper part toward the horizontal center position, and the upper end part is connected to the outlet header 68.

  In addition, a ceiling wall 115 is disposed below each lower support beam 113, and the ceiling wall 115 is formed by connecting a large number of heat transfer tubes with fins to constitute a ceiling portion of the flue 13. The plurality of second heat transfer tubes 102 extend downward through the fins of the ceiling wall 115, and the lower end portion is connected to the intermediate header 67, so that the intermediate header 67 is connected to the plurality of second heat transfer tubes 102. The suspension is supported. In the present embodiment, the intermediate header 67 is provided along the direction in which the plurality of first heat transfer tubes 101 and the plurality of second heat transfer tubes 102 are juxtaposed (the left-right direction in FIG. 4), and the plurality of first heat transfer tubes 101. A plurality (three in this embodiment) are arranged in parallel in the horizontal direction (left and right in FIG. 3) perpendicular to the direction in which the heat transfer tubes 101 and the plurality of second heat transfer tubes 102 are arranged. .

  In this case, the three intermediate headers 67 are arranged at equal intervals in the longitudinal direction of the plurality of first heat transfer tubes 101 (left and right direction in FIG. 3). However, the number of intermediate headers 67 is not limited to three, and may be set as appropriate according to the width of the flue 13 (combustion gas passage 60), and arranged at equal intervals as necessary. You don't have to.

  As shown in detail in FIG. 6, the supporting form of the plurality of first heat transfer tubes 101 by the intermediate headers 67 is supported by the supporting parts 117 suspended by ring-shaped hanging parts 116. Each support tool 117 has a ladder shape, and a plurality of first heat transfer tubes 101 bent in a corrugated shape are horizontally inserted. Therefore, the plurality of first heat transfer tubes 101 are supported by the respective support tools 117, supported by being suspended from the respective intermediate headers 67 by the suspension tools 116, and the upper end portions thereof are coupled to the respective intermediate headers 67. The plurality of first heat transfer tubes 101 are coupled to the inlet header 65 with the lower ends gathered in the middle.

  In the present embodiment, the first economizer 47 is configured by a plurality of first heat transfer tubes 101, and the second economizer 46 is configured by a plurality of second heat transfer tubes 102, and the plurality of first heat transfer tubes. 101 and a plurality of second heat transfer tubes 102 are connected to the intermediate header 67. Therefore, the number of the plurality of first heat transfer tubes 101 and the number of the plurality of second heat transfer tubes 102 can be made different. In the present embodiment, the number of the plurality of first heat transfer tubes 101 is larger than the number of the plurality of second heat transfer tubes 102. Further, the plurality of first heat transfer tubes 101 of the first economizer 47 can all be connected to the intermediate header 67. For this reason, it is possible to equalize the boiler feed water flowing into the plurality of first heat transfer tubes 101, which is preferable in order to equalize the heat transfer performance of the plurality of first heat transfer tubes 101.

  Further, since the first reheater 45 is disposed adjacent to the second economizer 46, the plurality of heat transfer tubes 103 of the first reheater 45 are supported by the plurality of second heat transfer tubes 102. Yes. That is, the plurality of second heat transfer tubes 102 are provided with a plurality of support portions, and the plurality of heat transfer tubes 103 in the first reheater 45 are supported by the plurality of support portions. In the present embodiment, the first reheater 45 is disposed adjacent to the second economizer 46, but the superheaters 41, 42, and 43 are disposed adjacent to the second economizer 46. In this case, the plurality of heat transfer tubes 103 in the superheaters 41, 42, and 43 are supported by the plurality of support portions. Therefore, in this embodiment, the plurality of second heat transfer tubes 102 of the second economizer 46 supports the plurality of heat transfer tubes 103 of the adjacent first reheater 45, and further supports the intermediate header 67, A plurality of first heat transfer tubes 101 of the first economizer 47 are suspended and supported by the intermediate header 67.

  Here, the repair method of the heat exchanger tube in the economizer of this embodiment is demonstrated. 7 and 8 are schematic views showing a heat transfer tube repair method in the economizer, FIGS. 9 and 10 are cross-sectional views showing a heat transfer tube nozzle blockage method, and FIG. 11 is for a heat transfer tube. FIG. 12 is a cross-sectional view illustrating another method for closing the nozzle for heat transfer tubes.

  The repair method of the heat transfer tube in the economizer of the present embodiment includes a step of cutting a nozzle base of the intermediate header 67 to which the first heat transfer tube 101 having a leakage portion is connected, and a first heat transfer tube 101 having the leakage portion. There are a step of cutting a nozzle of the inlet header 65 to be connected, a step of closing the nozzle of the cut intermediate header 67, and a step of closing the nozzle of the cut inlet header 65.

  Moreover, the repair method of the heat exchanger tube in the economizer of the present embodiment includes a step of cutting the nozzle base of the blocked intermediate header 67, a step of cutting the nozzle header of the blocked inlet header 65, and a new first heat transfer tube. A step of connecting one end of 101 to the nozzle of the intermediate header 67, and a step of connecting the other end of the new first heat transfer tube 101 to the nozzle of the inlet header 65.

  More specifically, when leakage occurs in the economizer, the operation of the coal fired boiler 10 is stopped, and each heat transfer of the superheaters 41, 42, 43, the reheaters 44, 45, and the economizers 46, 47 is performed. Drain the inside of the pipe. As shown in FIG. 7, when the first heat transfer tube 101 of the first economizer 47 is leaking, the first heat transfer tube 101 in which the leakage portion D is generated from the plurality of first heat transfer tubes 101 is specified. When the first heat transfer tube 101 with the leakage portion D is specified, first, the connection portion with the intermediate header 67 to which the upper end portion of the first heat transfer tube 101 with the leakage portion D is connected, and the lower end portion are connected. Each connecting portion with the inlet header 65 is cut.

That is, as shown in FIG. 9, the inlet header 65 has a heat transfer tube connecting nozzle 121 fixed by welding, and the lower end portion of the first heat transfer tube 101 is connected to the nozzle 121 by welding. Thus, the first heat transfer tube 101 is connected to the inlet header 65. Therefore, here, as shown in FIG. 10, by cutting the nozzle base 121 of the inlet header 65 to which the lower end portion of the first heat transfer tube 101 having the leaking portion D is connected, two parts (cut portions) ) 121a is removed.
In this case, the length of the residual nozzle 121b after the cutting is left to be a predetermined length, and the predetermined length is preferably set in a range of 5 mm to 25 mm.

  This is because the exhaust gas temperature in the vicinity of the intermediate header 65 in this embodiment is in an atmosphere as high as about 500 ° C. to about 550 ° C. For this reason, the length of the remaining nozzle 121b protruding from the cut intermediate header 65 increases as the length of the nozzle rises, and there is a concern that the strength may decrease. There is a need. On the other hand, considering the workability of the cutting operation, the closing operation, and the reconnection welding operation, it is desirable that the length of the residual nozzle 121b is as long as possible. The length of the cutting part 121a of the nozzle 121 is set in consideration of the workability of the cutting work and the closing work, but if the cutting nozzle 121c does not interfere with various works, the nozzle It is not necessary to secure the cutting part 121a by cutting 121 at one place.

  Although not shown, the intermediate header 67 has a heat transfer tube connecting nozzle fixed by welding in the same manner as the inlet header 65, and the upper end of the first heat transfer tube 101 is connected to the nozzle by welding. Thus, the first heat transfer tube 101 is connected to the intermediate header 67. Therefore, similarly to the nozzle 121 of the inlet header 65, the nozzle of the intermediate header 67 to which the upper end of the first heat transfer tube 101 having the leaking part D is connected is cut.

  When the connecting portion between the first heat transfer tube 101 having the leaking portion D, the intermediate header 67, and the inlet header 65 is cut, the cut base of the intermediate header 67 and the nozzle 121 of the inlet header 65 are closed. That is, as shown in FIG. 11, the stopper plug 122 is fitted into the end opening of the residual nozzle 121b of the inlet header 65, and the periphery thereof is welded W so that the stopper plug 122 is attached to the end opening of the residual nozzle 121b. Fix it. Note that the closing structure of the nozzle 121 of the inlet header 65 is not limited to this structure. As shown in FIG. 13, the stopper plug 123 is arranged at the end opening of the residual nozzle 121b of the inlet header 65, and the stopper plug 123 is fixed to the end opening of the residual nozzle 121b by welding the periphery. But you can. Although not shown, the end opening of the residual nozzle of the intermediate header 67 is also closed by fixing the closing plugs 122, 123 and the like.

  Then, as shown in FIG. 8, the first heat transfer tube 101 having the leakage portion D is cut off at the upper end portion and the lower end portion, and the use is stopped. By closing the nozzle of the inlet header 65 of the first heat transfer pipe 101 where the leakage of boiler feed water has occurred, the heat recovery amount of the first economizer 47 is reduced, and the boiler exhaust gas temperature rise is very small. This is because the number of first heat transfer tubes 101 provided in a general first economizer such as this embodiment is about 1000, and even if one of the first heat transfer tubes 101 is closed, the boiler outlet The effect of the heat transfer amount on the gas temperature rise is 1/1000, and the temperature rise is 0. This is because the temperature is a few degrees C or less and can be ignored.

  Furthermore, since there is the intermediate header 67, it is not necessary to close the plurality of second heat transfer tubes 102 of the second economizer 46, and even if the exhaust gas temperature is as high as about 1000 ° C., the second heat transfer tubes 102 Since boiler feed water passes through the inside, the temperature of the second heat transfer tube 102 does not rise abnormally and the strength does not decrease. Therefore, the plurality of heat transfer tubes 103 of the adjacent first reheaters 45 are supported, and further the intermediate header 67 is supported. The intermediate header 67 includes a plurality of first heat transfer tubes of the first economizer 47. 101 can continue the suspension support.

  In this case, the first heat transfer tube 101 that has been cut due to the leakage portion D is supported by the support 117 and is supported by the intermediate header 67 by the suspension 116 so that it does not fall off. . At this time, the first economizer 47 after the first heat transfer tube 101 is repaired includes a nozzle base of the intermediate header 67 to which the upper end portion of the first heat transfer tube 101 having the leakage portion D is connected, and a lower end. The nozzle of the inlet header 65 to which the sections are connected is closed. Then, after supplying water into the heat transfer tubes of the superheaters 41, 42, 43, the reheaters 44, 45, and the economizers 46, 47, the operation of the coal fired boiler 10 can be started at an early stage.

  When the maintenance time of the coal fired boiler 10 is reached, the first heat transfer tube 101 that has been cut due to the leakage portion D is removed and the new first heat transfer tube 101 is supported, and each end of the new first heat transfer tube 101 is then removed. Are connected to the inlet header 65 and the intermediate header 67. That is, the remaining nozzle of the closed intermediate header 67 is cut to remove the closing plugs 122 and 123, and the remaining nozzle of the closed inlet header 65 is cut to remove the closing plugs 122 and 123. And while connecting the upper end part of the new 1st heat exchanger tube 101 to the cutting part of the residual pipe base of the intermediate header 67, the lower end part of the new 1st heat transfer pipe 101 is connected to the cutting part of the residual pipe stage of the inlet header 65. . Then, the first economizer 47 can use all the first heat transfer tubes 101.

  Thus, in the economizer of the present embodiment, the first economizer 47 in which the plurality of first heat transfer tubes 101 having a waveform shape are arranged in parallel in the horizontal direction with a predetermined interval, and the plurality of first economizers. An inlet header 65 connected to the lower end portion in the vertical direction of the first heat transfer tube 101 and a plurality of second heat transfer tubes 102 arranged in the vertical direction above the first economizer 47 and extending along the vertical direction are spaced apart from each other by a predetermined interval. The second economizer 46 arranged in parallel in the horizontal direction, the outlet header 68 connected to the upper end of the plurality of second heat transfer tubes 102 in the vertical direction, and the vertical direction of all the plurality of first heat transfer tubes 101 And an intermediate header 67 that is connected to the lower ends in the vertical direction of all of the plurality of second heat transfer tubes 102.

  Therefore, the 2nd economizer 46 which consists of a plurality of 2nd heat exchanger tubes 102 along the perpendicular direction is arranged above the 1st economizer 47 which consists of a plurality of 1st heat exchanger tubes 101 which make a waveform shape, and each 1st By connecting the intermediate header 67 between the upper end portion of the heat transfer tube 101 and the lower end portion of each second heat transfer tube 102, the first heat transfer tube 101 and the second heat transfer tube 102 can function independently. . Further, all the water supply flowing through each first heat transfer tube 101 can be once collected in the intermediate header 67, and from there, it flows into each second heat transfer tube 102, and the boiler water supply flowing through each second heat transfer tube 102 is averaged. Can be compressed. Moreover, since the 1st economizer and the 2nd economizer 46 can be managed individually via the intermediate header 67, the design freedom can be expanded and the operation becomes easy.

  For example, when a leak location occurs in a part of the first heat transfer tube 101, the first economizer 47 can be obtained by simply closing the nozzle header 65 and the intermediate header 67 in the first heat transfer tube 101. Can function. Even if one of the headers of the inlet header 65 of the first heat transfer tube 101 where the boiler feed water leaks is closed, the influence of the heat transfer amount on the rise of the boiler outlet gas temperature is so small that it can be ignored. At this time, it is not necessary to close the second heat transfer tubes 102, and the function of the second economizer 46, which is a high-temperature exhaust gas atmosphere, does not deteriorate from the first economizer 47. Can be sufficiently cooled, and damage can be prevented. As a result, it is possible to quickly repair the leakage of the first heat transfer tube 101, improve workability in the repair work of the first heat transfer tube 101, restart the coal fired boiler 10 early, and improve the operating rate of the boiler. Can be achieved. In this case, in the plurality of first heat transfer tubes 101, the closed first heat transfer tubes 101 are not connected to the intermediate header 67.

  Moreover, here, managing the 1st economizer and the 2nd economizer 46 individually means determining the presence or absence of leakage in each of the heat transfer tubes 101 and 102 independently. At the time of regular inspection of the boiler, water is allowed to flow through each of the heat transfer tubes 101, 102, or pressure drop is monitored visually during operation to determine whether or not each heat transfer tube 101, 102 is leaking. Is called management.

  In the economizer of the present embodiment, the second heat transfer tube 102 has an upper portion that penetrates the lower support beam 113 and is prevented from moving downward with respect to the lower support beam 113 by the locking piece 114, and an intermediate header 67 is connected to the lower end portion. doing. Therefore, since the intermediate header 67 is suspended and supported by the lower support beam 113 via the second heat transfer tube 102, a lifting tool for supporting the intermediate header 67 on the lower support beam 113 becomes unnecessary, and the structure is complicated. And an increase in manufacturing cost can be suppressed.

  In the economizer of the present embodiment, the first heat transfer tube 101 is suspended and supported by the intermediate header 67 by the hanger 116, and the upper end portion is connected to the intermediate header 67. Accordingly, the first heat transfer tube 101 is connected to the intermediate header 67 in a state of being supported by being suspended from the intermediate header 67 by the lifting tool 116, so that the first heat transfer tube 101 is supported by the lower support beam 113. A tool becomes unnecessary and the 1st heat exchanger tube 101 and the intermediate header 67 can be connected easily, and complication of a structure and an increase in manufacturing cost can be controlled.

  In the economizer of the present embodiment, the intermediate header 67 is disposed in the combustion gas passage 60. Therefore, by arranging the intermediate header 67 in the combustion gas passage 60, the first heat transfer tube 101, the intermediate header 67, and the second heat transfer tube 102 can be easily connected, and the structure can be simplified. it can.

  In the economizer of the present embodiment, the intermediate header 67 is provided along the direction in which the heat transfer tubes 101 and 102 are juxtaposed, and at a predetermined interval in the horizontal direction perpendicular to the direction in which the heat transfer tubes 101 and 102 are juxtaposed. It is installed side by side. Therefore, by arranging a plurality of intermediate headers 67 at predetermined intervals, the plurality of first heat transfer tubes 101, the plurality of intermediate headers 67, and the plurality of second heat transfer tubes 102 are connected, and the heat transfer tubes 101, 102 are connected. The piping length can be shortened to simplify the structure and reduce the cost.

  In the economizer of the present embodiment, the number of first heat transfer tubes 101 is greater than the number of second heat transfer tubes 102. Accordingly, since the plurality of first heat transfer tubes 101 and the plurality of second heat transfer tubes 102 are connected by the intermediate header 67, the number of the first heat transfer tubes 101 and the second heat transfer tubes 102 can be made different, and the degree of freedom in design. Can be spread. In addition, by providing a greater number of first heat transfer tubes 101 than the number of second heat transfer tubes 102, the number of first heat transfer tubes 101 arranged in the low temperature region can be increased to increase the amount of heat absorption, thereby improving the heat exchange efficiency. Can be improved.

  In the economizer of the present embodiment, the plurality of second heat transfer tubes 102 are provided with support portions 118 that support the heat transfer tubes 103 of the first reheater 45. Therefore, by supporting the heat transfer tube 103 of the first reheater 45 by the support portion 118 of the second heat transfer tube 102, a support member for supporting the heat transfer tube 103 of the first reheater 45 is unnecessary, and the structure The increase in complexity and the manufacturing cost can be suppressed.

  In the economizer of this embodiment, the nozzle base of the intermediate header 67 to which the upper end portion of the first heat transfer tube 101 having the leakage portion D is connected and the lower end portion of the first heat transfer tube 101 having the leakage portion D are connected. The nozzle of the inlet header 65 is closed. Therefore, the economizers 46 and 47 can be used continuously by closing the nozzles of the intermediate header 67 and the inlet header 65 in the first heat transfer tube 101 having the leakage portion D.

  Further, the length of the residual nozzle 121b protruding from the intermediate header 65 after cutting the nozzle 121 of the inlet header 65 to which the lower end of the first heat transfer tube 101 having the leakage portion D is connected is 5 mm to It is preferable to set in the range of 25 mm. This is because if it exceeds 25 mm, the temperature of the nozzle rises due to the exhaust gas temperature in the vicinity, the strength decreases, and if it is less than 5 mm, the workability of the cutting operation, the closing operation, and the reconnection welding operation becomes difficult. By setting the length of the residual nozzle 121b within this range, the remaining nozzle 121b can be soundly closed and repaired.

  Further, in the boiler of the present embodiment, a furnace 11 that is hollow and installed along the vertical direction, a combustion device 12 that is disposed in the furnace 11, and an upper part of the furnace 11 are connected to exhaust gas. The flue 13 to flow, the superheaters 41, 42, and 43, the reheaters 44 and 45, and the economizers 46 and 47 arranged in the flue 13 are provided.

  Accordingly, the upper end portion of each first heat transfer tube 101 of the first economizer 47 disposed below and the lower end portion of each second heat transfer tube 102 of the second economizer 46 disposed above are intermediate headers. By connecting by 67 and comprising a economizer, the 1st heat exchanger tube 101 and the 2nd heat exchanger tube 102 can be functioned independently. For example, when a leak location occurs in a part of the first heat transfer tube 101, the first economizer 47 can be obtained by simply closing the nozzle header 65 and the intermediate header 67 in the first heat transfer tube 101. Can function.

  At this time, since there is the intermediate header 67, it is not necessary to close the second heat transfer tube 102, and the temperature of the second heat transfer tube 102 does not rise abnormally and the strength does not decrease. The heat transfer tubes 103 and the intermediate header 67 are supported. The plurality of first heat transfer tubes 101 of the first economizer 47 can continue to be suspended and supported on the intermediate header 67. Moreover, the function of the 2nd economizer 46 which is a high temperature exhaust gas atmosphere does not fall by the 1st economizer 47, each 2nd heat exchanger tube 102 can fully be cooled, and damage can be prevented. it can. As a result, the first heat transfer tube 101 can be repaired at an early stage, the workability in the repair work of the first heat transfer tube 101 can be improved, the coal-fired boiler 10 is restarted early, and the boiler operating rate Can be improved.

  In the boiler of this embodiment, superheaters 41, 42, 43 and reheaters 44, 45 are provided as one of the heat exchangers, and the heat transfer tube 103 of the first reheater 45 is supported by the second heat transfer tube 102. doing. Therefore, by supporting the heat transfer tube 103 of the first reheater 45 by the second heat transfer tube 102, a support member for supporting the heat transfer tube 103 of the first reheater 45 is unnecessary, and the structure is complicated. An increase in manufacturing cost can be suppressed.

  Further, in the heat transfer tube repairing method of the present embodiment, the step of cutting the nozzle of the intermediate header 67 to which the first heat transfer tube 101 having the leakage portion D is connected, and the first transfer having the leakage portion D are performed. A step of cutting the nozzle base of the inlet header 65 to which the heat pipe 101 is connected, a step of closing the nozzle base of the cut intermediate header 67, and a step of closing the nozzle base of the cut inlet header 65. ing.

  Therefore, for example, when a leak location occurs in a part of the first heat transfer tube 101, the second heat transfer tube can be obtained by simply closing the nozzle header 65 and the intermediate header 67 in the first heat transfer tube 101. There is no need to block 102, and the first heat transfer tube 101 can be repaired at an early stage, and the workability in the repair work of the first heat transfer tube can be improved.

  In the heat transfer tube repairing method of the present embodiment, the step of cutting the nozzle base of the closed intermediate header 67, the step of cutting the nozzle base of the closed inlet header 65, and one end of the new first heat transfer tube 101 are intermediate. It has the process of connecting with the nozzle of the header 67, and the process of connecting the other end part of the new 1st heat exchanger tube 101 with the nozzle of the inlet header 65. Therefore, at the time of maintenance of the economizers 46 and 47, the first economizer 47 can be easily returned to the initial state by connecting the new first heat transfer tube 101 to the nozzle block temporarily closed. it can. The coal-fired boiler 10 can be restarted at an early stage to improve the operating rate of the boiler.

  In the above-described embodiment, the shape, arrangement, and number of the first heat transfer tubes 101 in the first economizer 47 and the shape, arrangement, and number of the second heat transfer tubes 102 in the second economizer 46 are as described above. It is not limited to the above, but may be appropriately set according to the shape and size of the flue 13.

  In the above-described embodiment, the boiler according to the present invention is a coal-fired boiler. However, the solid fuel may be a boiler using biomass, petroleum coke, petroleum residue, or the like. Further, the fuel can be used not only for solid fuel but also for oil-fired boilers such as heavy oil, and further, gas (by-product gas) can also be used as fuel. And it can apply also to the mixed combustion sowing of these fuels.

10 Coal-fired boiler (boiler)
DESCRIPTION OF SYMBOLS 11 Furnace 12 Combustion apparatus 13 Flue 21, 22, 23, 24, 25 Combustion burner 41, 42, 43 Superheater (heat exchanger)
44 Second reheater (heat exchanger)
45 1st reheater (heat exchanger)
46 Second economizer (heat exchanger)
47 First economizer (heat exchanger)
60 Combustion gas passage 61 Steam turbine 65 Inlet header 67 Intermediate header 68 Outlet header 101 First heat transfer tube 102 Second heat transfer tube 111 Upper support beam 112 Suspension rod 113 Lower support beam (support beam)
114 Locking piece (locking member)
115 Ceiling wall 121 Tubular 122,123 Closing stopper D Leakage part

Claims (12)

A economizer provided in a combustion gas passage in which combustion gas flows from the upper part to the lower part in the vertical direction,
A first economizer in which a plurality of first heat transfer tubes having a corrugated shape are arranged in parallel in a horizontal direction at a predetermined interval;
An inlet header connected to the lower end portion in the vertical direction of the plurality of first heat transfer tubes;
A second economizer that is arranged above the first economizer in the vertical direction and in which a plurality of second heat transfer tubes along the vertical direction are arranged in parallel in a horizontal direction with a predetermined interval;
An outlet header connected to an upper end portion in a vertical direction of the plurality of second heat transfer tubes;
An intermediate header that can be connected to the upper ends of the plurality of first heat transfer tubes in the vertical direction and is connected to the lower ends of the plurality of second heat transfer tubes in the vertical direction;
Have
The first economizer and the second economizer are individually managed through the intermediate header.   In the second heat transfer tube, the upper part in the vertical direction penetrates the support beam, and the downward movement in the vertical direction with respect to the support beam is prevented by the locking member, and the intermediate header is connected to the lower end part and supported by being suspended. The economizer according to claim 1.   3. The economizer according to claim 2, wherein the first heat transfer tube is suspended and supported by the intermediate header by a lifting tool, and an upper end portion is coupled to the intermediate header.   The economizer according to any one of claims 1 to 3, wherein the intermediate header is disposed in the combustion gas passage.   The intermediate header is provided along a parallel arrangement direction of the plurality of first heat transfer tubes and the plurality of second heat transfer tubes, and a parallel arrangement direction of the plurality of first heat transfer tubes and the plurality of second heat transfer tubes. 5. The economizer according to claim 1, wherein a plurality of the economizers are arranged in parallel in a horizontal direction orthogonal to each other at a predetermined interval.   The economizer according to any one of claims 1 to 5, wherein the number of the plurality of first heat transfer tubes is larger than the number of the plurality of second heat transfer tubes.   The economizer according to any one of claims 1 to 6, wherein the plurality of second heat transfer tubes are provided with a support portion that supports a heat transfer tube of another heat exchanger.   The intermediate header tube base to which one end portions of the plurality of first heat transfer tubes having the leaking portion are connected, and the inlet header nozzle base to which the other end portion of the first heat transfer tube having the leaking portion is connected. The economizer according to any one of claims 1 to 7, characterized in that is closed.   9. The length of the nozzle base remaining on the intermediate header after cutting the first heat transfer tube having the leakage portion is in a range of 5 mm to 25 mm. The economizer described in the paragraph. A furnace that is hollow and installed along the vertical direction;
A combustion device disposed in the furnace;
A flue connected to the upper part of the furnace for flowing combustion gas;
A heat exchanger disposed in the flue;
With
The economizer according to any one of claims 1 to 9 is provided as one of the heat exchangers.
A boiler characterized by that.   The superheater or the reheater is provided as one of the heat exchangers, and the heat transfer tube of the superheater or the reheater is supported by the second heat transfer tube. boiler. A method of repairing a heat transfer tube in a economizer,
A first economizer in which a plurality of first heat transfer tubes having a corrugated shape provided in a combustion gas passage through which combustion gas flows from the upper part to the lower part in the vertical direction are arranged in parallel in a horizontal direction at a predetermined interval;
An inlet header connected to the lower end portion in the vertical direction of the plurality of first heat transfer tubes;
A second economizer that is arranged above the first economizer in the vertical direction and in which a plurality of second heat transfer tubes along the vertical direction are arranged in parallel in a horizontal direction with a predetermined interval;
An outlet header connected to an upper end portion in a vertical direction of the plurality of second heat transfer tubes;
An intermediate header that can be connected to the upper ends in the vertical direction of all of the plurality of first heat transfer tubes and connected to the lower ends of the plurality of second heat transfer tubes in the vertical direction. And
The first economizer and the second economizer are individually managed via the intermediate header,
Cutting the nozzle of the intermediate header to which the first heat transfer tube having a leakage portion is connected, leaving a predetermined length;
Cutting the nozzle of the inlet header to which the first heat transfer tube having the leakage portion is connected, leaving the predetermined length;
Closing the cut nozzle of the intermediate header;
Clogging the nozzle of the cut inlet header;
A method of repairing a heat transfer tube, characterized by comprising:

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