JP7221438B1 - Heat exchanger, flue gas treatment device, and method for manufacturing heat exchanger - Google Patents

Abstract

An object of the present invention is to improve heat exchange efficiency in a bundle, a heat exchanger, a flue gas treatment apparatus, and a method for manufacturing the bundle. A duct casing, a plurality of heat transfer tubes arranged in a zigzag pattern inside the duct casing, and a guide extending from the duct casing toward the heat transfer tubes on the most upstream side in the direction of gas flow from the plurality of heat transfer tubes. and a member. [Selection drawing] Fig. 1

Description

The present disclosure relates to bundles, heat exchangers, flue gas treatment devices, and methods of manufacturing bundles.

A flue gas treatment device installed in a thermal power plant or the like is composed of a heat recovery device, an electrostatic precipitator, a desulfurization device, a reheating device, and the like. Exhaust gas discharged from the boiler is freed of dust contained in the exhaust gas by an electrostatic precipitator, and is freed of sulfurous acid gas by a desulfurization device. At this time, the heat recovery device recovers heat from the exhaust gas. The reheating device reheats the exhaust gas after desulfurization with the heat recovered by the heat recovery device, thereby suppressing emission of white smoke.

The reheating device has a plurality of heat transfer tubes arranged in the exhaust gas passage. The reheating device heats and raises the temperature of the exhaust gas by causing a high-temperature heat medium to flow through the plurality of heat transfer tubes and exchanging heat between the heat medium and the exhaust gas flowing through the exhaust gas passage. As a conventional reheating device, for example, there is one described in Patent Document 1 below.

JP-A-2001-99418

The reheater is configured by connecting an inlet header and an outlet header with a plurality of heat transfer tubes. In this case, the plurality of heat transfer tubes are configured by connecting a plurality of straight portions with a U-shaped portion. In the conventional reheater, a plurality of linear portions are arranged in a zigzag pattern.

The exhaust gas flowing into the reheating device is heated by the high-temperature heat medium flowing through the plurality of heat transfer tubes by coming into contact with the plurality of heat transfer tubes. In this case, since the plurality of heat transfer tubes are arranged in a zigzag pattern inside the duct casing, some of the heat transfer tubes are positioned apart from the inner wall surface of the duct casing. As a result, the exhaust gas passes through the gap between the duct casing and the heat transfer tube, resulting in a problem of reduced heat exchange efficiency.

An object of the present disclosure is to solve the above-described problems, and to provide a bundle, a heat exchanger, a flue gas treatment apparatus, and a method for manufacturing the bundle that improve heat exchange efficiency.

The bundle of the present disclosure for achieving the above object comprises a duct casing, a plurality of heat transfer tubes arranged in a staggered manner inside the duct casing, and the most upstream side of the plurality of heat transfer tubes in the direction of gas flow. and a guide member extending from the duct casing toward the heat transfer tube.

Further, the heat exchanger of the present disclosure includes an exhaust gas passage defined by the duct casing, and the bundle arranged in the exhaust gas passage.

Further, the flue gas treatment apparatus of the present disclosure includes a heat recovery device that recovers part of the heat of exhaust gas, a dust collector that removes soot and dust contained in the exhaust gas after heat recovery, and a A desulfurization device for removing contained sulfur oxides, and a reheating device to which the heat exchanger for reheating the exhaust gas after desulfurization is applied.

In addition, in the bundle manufacturing method of the present disclosure, in a bundle in which one longitudinal end of a plurality of heat transfer tubes is connected to a header and arranged inside a duct casing, the heat transfer tubes are arranged at the maximum in the flow direction of the exhaust gas from the plurality of heat transfer tubes. A guide member extending from the duct casing toward the heat transfer tube is fixed by welding on the upstream side.

According to the bundle, the heat exchanger, the flue gas treatment device, and the method for manufacturing the bundle of the present disclosure, it is possible to improve the heat exchange efficiency.

FIG. 1 is a schematic configuration diagram showing the flue gas treatment apparatus of this embodiment. FIG. 2 is a schematic configuration diagram showing the reheating device of this embodiment. FIG. 3 is a schematic side view of the reheating device. FIG. 4 is a schematic plan view showing the reheating device. FIG. 5 is a schematic diagram showing the heat transfer tube of this embodiment. FIG. 6 is a table showing the configuration of the heat transfer tubes in the reheating device of this embodiment. FIG. 7 is a schematic side view showing the high temperature preheating section. FIG. 8 is a schematic front view showing the high temperature preheating section. FIG. 9 is a cross-sectional view showing the relationship between the header and heat transfer tubes before connection. FIG. 10 is a cross-sectional view showing the connecting portion between the header and the heat transfer tube after connection. FIG. 11 is a cross-sectional view showing the upper ends of the heat transfer tubes connected to the header. FIG. 12 is a cross-sectional view showing a connecting portion at the lower ends of adjacent heat transfer tubes. FIG. 13 is a cross-sectional view of the periphery of the header showing the relationship between the flange joints and the heat transfer tubes. FIG. 14 is a cross-sectional view of the periphery of the header showing the relationship between the flange joints and the heat transfer tubes. FIG. 15 is a schematic diagram showing the relationship between the header and the heat transfer tubes in the high temperature preheating section. FIG. 16 is a schematic diagram showing a water-filled state for the high-temperature preheating section. FIG. 17 is a schematic cross-sectional view for explaining a method of filling the heat transfer tubes with water. FIG. 18 is a schematic front view showing the essential parts of the high-temperature preheating section. FIG. 19 is a horizontal cross-sectional view showing the essential parts of the high-temperature preheating section. FIG. 20 is a vertical cross-sectional view showing support portions for heat transfer tubes in the high-temperature preheating section. FIG. 21 is a horizontal cross-sectional view showing support portions for heat transfer tubes in the high-temperature preheating section.

Preferred embodiments of the present disclosure will be described in detail below with reference to the drawings. It should be noted that the present disclosure is not limited by this embodiment, and when there are a plurality of embodiments, the present disclosure also includes a combination of each embodiment. In addition, components in the embodiments include those that can be easily assumed by those skilled in the art, those that are substantially the same, and those that are within the so-called equivalent range.

[Smoke exhaust treatment equipment]
FIG. 1 is a schematic configuration diagram showing the flue gas treatment apparatus of this embodiment.

As shown in FIG. 1, the flue gas treatment apparatus 100 is used in various power plants, factories, etc., in the process in which the flue gas (flue gas) G emitted from a boiler 111 is emitted from a stack 112. It removes dust and sulfur oxides (SOx).

The flue gas treatment device 100 includes a heat recovery device 101, an electric dust collector 102, a blower (induced draft fan) 103, a desulfurization device 104, a reheating device 105, and a blower (desulfurization fan) 106. Prepare. By driving the blowers 103 and 106 , the exhaust gas G discharged from the boiler 111 is sent to the stack 112 through the heat recovery device 101 , the electrostatic precipitator 102 , the desulfurization device 104 and the reheating device 105 . A denitration device may be provided upstream of the heat recovery device 101 .

The boiler 111 is provided with two exhaust gas passages 121a and 121b. The exhaust gas passage 121a is provided with a heat recovery device 101a, an electrostatic precipitator 102a and a blower 103a, and the exhaust gas passage 121b is provided with a heat recovery device 101b, an electrostatic precipitator 102b and a blower 103b. The two exhaust gas passages 121a and 121b join the exhaust gas passage 121c on the downstream side. A desulfurization device 104 and a reheating device 105 are provided in the exhaust gas passage 121c. The exhaust gas passage 121c branches downstream into two exhaust gas passages 121d and 121e. The exhaust gas passage 121d is provided with a blower 106a, and the exhaust gas passage 121e is provided with a blower 106b. The two exhaust gas passages 121d and 121e join the exhaust gas passage 121f on the downstream side. The flue gas passage 121f is connected to the chimney 112 . Further, an exhaust gas passage 121g is provided that connects the upstream side of the desulfurization device 104 in the exhaust gas passage 121c and the exhaust gas passage 121f. An on-off valve 122 is provided in the exhaust gas passage 121g.

The heat recovery device 101 (101a, 101b) recovers heat from the exhaust gas G (about 140° C.) discharged from the boiler 111 by exchanging heat between the exhaust gas G (about 140° C.) and a heat medium (such as water). The exhaust gas G (approximately 90° C.) heat-recovered by the heat recovery device 101 is introduced into the electrostatic precipitator 102 (102a, 102b). The electrostatic precipitator 102 removes dust from the exhaust gas G.

The exhaust gas G from which dust has been removed by the electrostatic precipitator 102 is introduced into the desulfurization device 104 . The desulfurization device 104 absorbs and removes sulfur oxides in the exhaust gas G with limestone (CaCO ₃ ) and produces gypsum (CaSO ₄ .2H ₂ O) as a by-product. The desulfurization device 104 has a mist eliminator 123 . The mist eliminator 123 removes mist from the exhaust gas G after desulfurization.

The exhaust gas G (about 50° C.) desulfurized by the desulfurization device 104 is introduced into the reheating device 105 of the gas gas heater. The reheating device 105 reheats the exhaust gas G with the heat recovered by the heat recovery device 101 in the process of circulating the heat medium with the heat recovery device 101 . The heat recovery device 101 and the reheating device 105 are connected by a first heat medium circulation line L11 and a second heat medium circulation line L12. A circulation pump 131 is provided in the first heat medium circulation line L11. By driving the circulation pump 131, the heat medium in the reheating device 105 is returned to the heat recovery device 101 through the first heat medium circulation line L11. A heater 132 is provided in the second heat medium circulation line L12. The circulation pump 131 supplies the heat medium in the heat recovery device 101 to the reheating device 105 through the second heat medium circulation line L12. In this process, the heat medium is heated by operating the heater 132 as necessary.

The flue gas G is desulfurized by the desulfurization device 104, and the temperature of the flue gas G is lowered. The reheating device 105 reheats the exhaust gas G to increase its temperature (approximately 90° C.) for the purpose of diffusion and reduction of white smoke, and discharges the exhaust gas into the atmosphere from the chimney 112 .

[Outline of reheating device]
FIG. 2 is a schematic configuration diagram showing the reheating device of this embodiment. In this embodiment, the heat exchanger is applied to the reheating device 105 in the flue gas treatment apparatus 100 described above.

As shown in FIG. 2, the reheating device 105 is a high temperature preheating countercurrent heat exchanger. However, the reheating device 105 may be a heat exchanger of another system such as a complete countercurrent system, a high temperature preheating cocurrent system, or a medium temperature preheating system.

The reheating device 105 has a high temperature heating section 11 , a low temperature heating section 12 and a high temperature preheating section 13 . The high-temperature heating section 11, the low-temperature heating section 12, and the high-temperature preheating section 13 are arranged in an exhaust gas passage (gas path) 121c. The high-temperature heating section 11, the low-temperature heating section 12, and the high-temperature preheating section 13 are arranged in order from the downstream side in the flow direction of the exhaust gas G. That is, the high-temperature heating section 11 is located on the most downstream side in the flow direction of the exhaust gas G, the high-temperature preheating section 13 is located on the most upstream side in the flow direction of the exhaust gas G, and the low-temperature heating section 12 is located on the high-temperature heating section 11 and the high temperature preheating section 13 .

The high temperature heating section 11 has a plurality of first heat transfer tubes 21 , a first header 22 and a second header 23 . The first heat transfer pipes 21 are arranged along the direction intersecting the flow direction of the exhaust gas G in the exhaust gas passage 121c. The first header 22 is located on the most downstream side in the flow direction of the exhaust gas G, and the second header 23 is located on the upstream side in the flow direction of the exhaust gas G from the first header 22 . The first header 22 is an inlet header and the second header 23 is an outlet header. The first heat transfer tubes 21 have one longitudinal end connected to the first header 22 and the other longitudinal end connected to the second header 23 .

The low temperature heating section 12 has a plurality of second heat transfer tubes 31 , a first header 32 and a second header 33 . The second heat transfer pipes 31 are arranged along the direction intersecting the flow direction of the exhaust gas G in the exhaust gas passage 121c. The first header 32 is located upstream of the second header 23 of the high-temperature heating unit 11 in the flow direction of the exhaust gas G, and the second header 33 is located upstream of the first header 32 in the flow direction of the exhaust gas G. . The first header 32 is an inlet header and the second header 33 is an outlet header. The second heat transfer tubes 31 have one longitudinal end connected to the first header 32 and the other longitudinal end connected to the second header 33 .

The high temperature preheating section 13 has a plurality of third heat transfer tubes 41 , a first header 42 and a second header 43 . The third heat transfer pipe 41 is arranged along the direction intersecting the flow direction of the exhaust gas G in the exhaust gas passage 121c. The first header 42 is located upstream of the second header 33 of the low-temperature heating unit 12 in the flow direction of the exhaust gas G, and the second header 43 is located upstream of the first header 42 in the flow direction of the exhaust gas G. . The first header 42 is an outlet header and the second header 43 is an inlet header. The third heat transfer tube 41 has one longitudinal end connected to the first header 42 and the other longitudinal end connected to the second header 43 .

The second heat medium circulation line L<b>12 has an upstream end in the flow direction connected to the heat recovery device 101 (see FIG. 1 ), and a downstream end connected to the second header 43 of the high-temperature preheating section 13 . . The first heat medium circulation line L<b>11 has a downstream end connected to the heat recovery device 101 (see FIG. 1 ) and an upstream end connected to the second header 33 of the low-temperature heating unit 12 . The first header 42 of the high temperature preheating section 13 and the first header 22 of the high temperature heating section 11 are connected by a first connection line L21. The second header 23 of the high temperature heating section 11 and the first header 32 of the low temperature heating section 12 are connected by a second connection line L22.

A circulation pump 131 and a drain tank 133 are provided in the first heat medium circulation line L11, and a heater 132 is provided in the second heat medium circulation line L12. A steam line L13 is provided from a steam supply source (not shown) to the heater 132 and the drain tank 133, and the drain tank 133 is provided with a steam drain line L14. An on-off valve 134 is provided in the steam line L13.

Therefore, the heat-recovered high-temperature heat medium is supplied to the second header 43 of the high-temperature preheating section 13 from the second heat medium circulation line L12. The heat medium supplied to the second header 43 flows through the plurality of third heat transfer tubes 41 to the first header 42 . At this time, the heat medium flowing through the third heat transfer pipe 41 preheats the exhaust gas G at a high temperature. The heat medium that has flowed through the first header 42 is supplied to the first header 22 of the high-temperature heating section 11 through the first connection line L21. The heat medium supplied to the first header 22 flows through the plurality of first heat transfer tubes 21 to the second header 23 . At this time, the heat medium flowing through the first heat transfer tube 21 heats the exhaust gas G to a high temperature. The heat medium that has flowed through the second header 23 is supplied to the first header 32 of the low-temperature heating section 12 through the second connection line L22. The heat medium supplied to the first header 32 flows through the plurality of second heat transfer tubes 31 to the second header 33 . At this time, the heat medium flowing through the second heat transfer pipe 31 heats the exhaust gas G at a low temperature. The heat medium that has flowed through the second header 33 is discharged to the first heat medium circulation line L11.

[Configuration of reheating device]
3 is a schematic side view showing the reheating device, and FIG. 4 is a schematic plan view showing the reheating device.

As shown in FIGS. 3 and 4 , the reheating device 105 has a high temperature heating section 11 , a low temperature heating section 12 and a high temperature preheating section 13 . The high temperature heating section 11 has a first bundle 51 , the high temperature heating section 11 has a second bundle 52 , and the low temperature heating section 12 has a third bundle 53 . The exhaust gas passage 121c is defined by the duct casing 60. As shown in FIG. The duct casing 60 has a rectangular tubular shape along the horizontal direction, and an exhaust gas passage 121c is defined therein, through which the exhaust gas G flows along the horizontal direction.

The first bundle 51 , the second bundle 52 and the third bundle 53 are connected to the upper wall portion 60 a of the duct casing 60 . The first bundle 51, the second bundle 52, and the third bundle 53 are arranged inside the duct casing 60 with a space therebetween from the upstream side toward the downstream side in the flow direction of the exhaust gas G.

That is, the first bundle 51 has the first header 22 and the second header 23 fixed to the upper wall portion 60 a of the duct casing 60 . A plurality of first heat transfer tubes 21 extend downward from the first header 22 and the second header 23 . In the first bundle 51, lower portions of the first header 22 and the second header 23 and the plurality of first heat transfer tubes 21 are positioned in the exhaust gas passage 121c. A first casing 54 is arranged on the outside of the first bundle 51 . The first casing 54 has its upper end fixed to the first header 22 and the second header 23 . The first casing 54 is arranged on both sides of at least the plurality of first heat transfer tubes 21, and is open upstream and downstream in the direction in which the exhaust gas G flows. In the first bundle 51, the upper portions of the first header 22 and the second header 23 are exposed outside the duct casing 60 and are not located in the exhaust gas passage 121c.

Also, the second bundle 52 has the first header 32 and the second header 33 fixed to the upper wall portion 60 a of the duct casing 60 . A plurality of second heat transfer tubes 31 extend downward from the first header 32 and the second header 33 . In the second bundle 52, the lower portions of the first header 32 and the second header 33 and the plurality of second heat transfer tubes 31 are positioned in the exhaust gas passage 121c. A second casing 55 is arranged on the outside of the second bundle 52 . The second casing 55 has its upper end fixed to the first header 32 and the second header 33 . The second casing 55 is arranged on both sides of at least the plurality of second heat transfer tubes 31, and is open upstream and downstream in the flow direction of the exhaust gas G. The upper portions of the first header 32 and the second header 33 of the second bundle 52 are exposed to the outside of the duct casing 60 and are not located in the exhaust gas passage 121c.

Also, the third bundle 53 has the first header 42 and the second header 43 fixed to the upper wall portion 60 a of the duct casing 60 . A plurality of third heat transfer tubes 41 extend downward from the first header 42 and the second header 43 . In the third bundle 53, lower portions of the first header 42 and the second header 43 and the plurality of third heat transfer tubes 41 are positioned in the exhaust gas passage 121c. A third casing 56 is arranged on the outside of the third bundle 53 . The third casing 56 has its upper end fixed to the first header 42 and the second header 43 . The third casing 56 is arranged on both sides of at least the plurality of third heat transfer tubes 41 and is open upstream and downstream in the flow direction of the exhaust gas G. The upper portions of the first header 42 and the second header 43 of the third bundle 53 are exposed to the outside of the duct casing 60 and are not located in the exhaust gas passage 121c.

In the first bundle 51 , the first header 22 has the flange joint 24 fixed to the top, and the second header 23 has the flange joint 25 fixed to the top. The flange joint 24 has a cylindrical shape and communicates with the inside of the first header 22 . The flange joint 25 has a cylindrical shape and communicates with the inside of the second header 23 . The flange joint 24 is arranged at one longitudinal end of the first header 22 , and the flange joint 25 is arranged at the other longitudinal end of the second header 23 . That is, the flange joint 24 and the flange joint 25 do not face each other in the flow direction of the exhaust gas G.

The first heat transfer tube 21 has a plurality of straight portions 21a, a plurality of upper curved portions 21b, and a plurality of lower curved portions 21c. The upper portions of adjacent linear portions 21a are connected to upper curved portions 21b, and the lower portions of adjacent linear portions 21a are connected to lower curved portions 21c. The first heat transfer tubes 21 are connected to the first header 22 at the upper end of the straight portion 21a on the downstream side in the flow direction of the exhaust gas G, and are connected to the second header at the upper end of the straight portion 21a on the upstream side in the flow direction of the exhaust gas G. 23. The first heat transfer tubes 21 are arranged along the surface direction along the flow direction of the exhaust gas G. As shown in FIG. The plurality of first heat transfer tubes 21 are arranged at intervals in the horizontal direction orthogonal to the flow direction of the exhaust gas G, thereby forming a first heat transfer tube group.

In the second bundle 52 , the first header 32 has the flange joint 34 fixed to the top, and the second header 33 has the flange joint 35 fixed to the top. The flange joint 34 has a cylindrical shape and communicates with the inside of the first header 32 . The flange joint 35 has a cylindrical shape and communicates with the inside of the second header 33 . The flange joint 34 is arranged at one longitudinal end of the first header 32 , and the flange joint 35 is arranged at the other longitudinal end of the second header 33 . That is, the flange joint 34 and the flange joint 35 do not face each other in the flow direction of the exhaust gas G.

The second heat transfer tube 31 has a plurality of straight portions 31a, a plurality of upper curved portions 31b, and a plurality of lower curved portions 31c. The upper portions of adjacent linear portions 31a are connected to upper curved portions 31b, and the lower portions of adjacent linear portions 31a are connected to lower curved portions 31c. The upper end of the straight portion 31a on the downstream side in the flow direction of the exhaust gas G is connected to the first header 32, and the upper end of the straight portion 31a on the upstream side in the flow direction of the exhaust gas G is connected to the second header. 33. The second heat transfer tubes 31 are arranged along the surface direction along the flow direction of the exhaust gas G. As shown in FIG. The plurality of second heat transfer tubes 31 are arranged at intervals in the horizontal direction perpendicular to the flow direction of the exhaust gas G, thereby forming a second heat transfer tube group.

In the third bundle 53 , the first header 42 has a flange joint 44 fixed to its upper portion, and the second header 43 has a flange joint 45 fixed to its upper portion. The flange joint 44 has a cylindrical shape and communicates with the inside of the first header 42 . The flange joint 45 has a cylindrical shape and communicates with the inside of the second header 43 . The flange joint 44 is arranged at one longitudinal end of the first header 42 , and the flange joint 45 is arranged at the other longitudinal end of the second header 43 . That is, the flange joint 44 and the flange joint 45 do not face each other in the flow direction of the exhaust gas G.

The third heat transfer tube 41 has a plurality of straight portions 41a, a plurality of upper curved portions 41b, and a plurality of lower curved portions 41c. The upper portions of adjacent linear portions 41a are connected to upper curved portions 41b, and the lower portions of adjacent linear portions 41a are connected to lower curved portions 41c. The upper end of the straight portion 41a on the downstream side in the flow direction of the exhaust gas G is connected to the first header 42, and the upper end of the straight portion 41a on the upstream side in the flow direction of the exhaust gas G is connected to the second header. 43. The third heat transfer pipes 41 are arranged along the surface direction along the flow direction of the exhaust gas G. As shown in FIG. The plurality of third heat transfer tubes 41 are arranged at intervals in the horizontal direction orthogonal to the flow direction of the exhaust gas G, thereby forming a second heat transfer tube group.

The second heat medium circulation line L12 is configured by piping and has a flange joint at the end. A pipe flange joint of the second heat medium circulation line L12 is connected to the flange joint 45 of the second header 43 of the third bundle 53 . The first connection line L21 is configured by piping and has flange joints at both ends. The first connection line L21 has a flange joint at one end of the pipe connected to the flange joint 44 of the first header 42 in the third bundle 53, and a flange joint at the other end of the pipe connected to the first header 22 in the first bundle 51. It is connected to the flange joint 24 . The second connection line L22 is configured by piping and has flange joints at both ends. The second connection line L22 connects the flange joint of one end of the pipe to the flange joint 25 of the second header 23 of the first bundle 51, and the flange joint of the other part of the pipe to the first header 32 of the second bundle 52. It is connected to the flange joint 34 . The first heat medium circulation line L11 is configured by piping and has a flange joint at its end. The first heat medium circulation line L<b>11 is connected to the flange joint 35 of the second header 33 of the second bundle 52 at the pipe flange joint.

[Operation of reheating device]
As shown in FIGS. 1 and 2, the heat recovery device 101 (101a, 101b) recovers heat from the exhaust gas G by exchanging heat between the exhaust gas G and a heat medium. The exhaust gas G from which heat has been recovered flows to the reheating device 105 through the electrostatic precipitator 102 and the desulfurization device 104 . On the other hand, the heat medium that has recovered the heat is sent to the reheating device 105 through the second heat medium circulation line L12.

The heat medium is supplied from the second heat medium circulation line L<b>12 to the high temperature preheating section 13 and flows from the second header 43 to the plurality of third heat transfer tubes 41 . The high-temperature preheating section 13 preheats the exhaust gas G by exchanging heat between the heat medium and the exhaust gas G flowing through the exhaust gas passage 121 c when the heat medium flows through the plurality of third heat transfer tubes 41 . The heat medium obtained by preheating the exhaust gas in the high-temperature preheating section 13 is supplied from the first header 42 to the high-temperature heating section 11 through the first connection line L21 and flows from the first header 22 to the plurality of first heat transfer tubes 21 . When the heat medium flows through the plurality of first heat transfer tubes 21, the high-temperature heating section 11 heats the exhaust gas G by exchanging heat between the heat medium and the exhaust gas G flowing through the exhaust gas passage 121c.

The heat medium heated by the high-temperature heating section 11 is supplied from the second header 23 to the low-temperature heating section 12 through the second connection line L22 and flows from the first header 32 to the plurality of second heat transfer tubes 31 . When the heat medium flows through the plurality of second heat transfer tubes 31, the low-temperature heating unit 12 heats the exhaust gas G by exchanging heat between the heat medium and the exhaust gas G flowing through the exhaust gas passage 121c. The heat medium heated by the low-temperature heating unit 12 is discharged from the second header 33 to the first heat medium circulation line L11 and sent to the heat recovery device 101 through the first heat medium circulation line L11.

[Configuration of heat transfer tube]
FIG. 5 is a schematic diagram showing the heat transfer tube of this embodiment, and FIG. 6 is a table showing the configuration of the heat transfer tube in the reheating device of this embodiment.

As shown in FIG. 5A, the third heat transfer tube 41 applied to the third bundle 53 constituting the high temperature preheating section 13 is a bare tube without fins. The third heat transfer tube 41 has a straight portion 41a, an upper curved portion 41b, and a lower curved portion 41c (see FIG. 3 for all). The straight portion 41a has a blank tube 41a1. The base pipe 41a1 is a pipe having a cylindrical shape. The heat medium W flows inside the third heat transfer tube 41, and the exhaust gas G flows outside so as to be perpendicular to the straight portion 41a.

In the high-temperature preheating section 13, a plurality of third heat transfer tubes 41 are arranged in a zigzag pattern. The exhaust gas G flowing into the reheating device 105 contains corrosive impurity-containing mist and the like. Since the high-temperature preheating section 13 is arranged on the most upstream side of the reheating device 105, the corrosive impurity-containing mist contained in the exhaust gas G passes first, so the corrosive environment is not good. Therefore, the third heat transfer tubes 41 are bare tubes without fins, and the plurality of third heat transfer tubes 41 are arranged in a staggered manner to ensure heat transfer performance.

As shown in FIG. 5B, the first heat transfer tube 21 and the second heat transfer tube 31 applied to the first bundle 51 and the second bundle 52 constituting the high temperature heating section 11 and the low temperature heating section 12 have fins. It is a fin tube provided. Since the first heat transfer tube 21 and the second heat transfer tube 31 have substantially the same shape, the second heat transfer tube 31 will be described, and the description of the first heat transfer tube 21 will be omitted. The heat medium W flows inside the second heat transfer tube 31, and the exhaust gas G flows outside so as to be perpendicular to the straight portion 31a.

The second heat transfer tube 31 has a straight portion 31a, an upper curved portion 31b, and a lower curved portion 31c (see FIG. 3 for all). The straight portion 31a has a base tube 31a1 and fins 31a2. The base pipe 31a1 is a pipe having a cylindrical shape. Fins 31a2 are fixed to the outer peripheral surface of the base pipe 31a1. The fins 31a2 are fixed to the outer peripheral surface of the base pipe 31a1 so as to form a spiral shape. Therefore, the second heat transfer tubes 31 are configured as finned tubes. A finned tube as the second heat transfer tube 31 has fins 31a2 fixed only to the raw tube 31a1 of the straight portion 31a.

In the low-temperature heating unit 12, a plurality of second heat transfer tubes 31 are arranged in a grid pattern. Since the low-temperature heating section 12 is arranged in the middle stage of the reheating device 105 , the corrosion environment is better than that of the high-temperature preheating section 13 . Therefore, the second heat transfer tubes 31 are finned tubes, and the plurality of second heat transfer tubes 31 are arranged in a grid pattern. In the high-temperature heating section 11, similarly to the low-temperature heating section 12, the first heat transfer tubes 21 are finned tubes and are arranged in a grid pattern.

Further, as described above, the high-temperature heating section 11, the low-temperature heating section 12, and the high-temperature preheating section 13 are different in temperature and corrosive environment, so that the raw pipes and fins are made of different materials.

As shown in FIG. 6, the high-temperature preheating section 13 has the worst corrosive environment because the exhaust gas G first flows thereinto. Therefore, a bare tube is used as the third heat transfer tube 41, and six straight portions 41a are arranged. In the third heat transfer tube 41, the blank tube 41a1 of the straight portion 41a is made of duplex stainless steel. The base pipe 41a1 is preferably made of general-purpose duplex stainless steel. Duplex stainless steels are classified into lean duplex steels, general-purpose duplex steels, super duplex steels, and the like. General-purpose duplex steel has excellent seawater corrosion resistance. As general-purpose duplex steel, for example, SUS329J4L is most preferable, but SUS329J1, SUS329J3L, etc. may also be used. Moreover, as a super duplex steel, there exists SUS327L1 etc., for example.

In the third heat transfer tube 41, the upper curved portion 41b and the lower curved portion 41c are made of austenitic stainless steel. As the austenitic stainless steel, for example, SUS316L is preferable.

Since the exhaust gas G flows into the low-temperature heating section 12 after the high-temperature preheating section 13 , the corrosion environment is better than that of the high-temperature preheating section 13 . Therefore, the second heat transfer tube 31 is a finned tube, and 12 straight portions 31a are arranged. The low-temperature heating section 12 is divided into three stages in the flow direction of the exhaust gas G into an upstream stage, a midstream stage, and a downstream stage. However, the number of divisions is not limited to three, and may be two or four or more. The upstream stage, the midstream stage and the downstream stage have the same number of stages. However, the upstream stage, the midstream stage, and the downstream stage may have different numbers of stages. The second bundle 52 that constitutes the low-temperature heating section 12 has a height in the Z direction and a width in the Y direction of 3.3 m to 3.5 m when viewed from the upstream side in the flow direction of the exhaust gas G.

At the upstream stage (1st to 3rd stages) of the second heat transfer tube 31, the raw tube 31a1 of the straight portion 31a is made of duplex stainless steel such as SUS329J4L, SUS329J1, SUS329J3L, or the like. The raw tube 31a1 of the straight portion 31a may be made of carbon steel STB340. On the other hand, in the upstream stage of the second heat transfer tube 31, the fins 31a2 of the straight portion 31a are made of austenitic stainless steel. As the austenitic stainless steel, for example, SUS316L is preferable. Also, in the upstream stage of the second heat transfer tube 31, the upper curved portion 31b and the lower curved portion 31c are made of austenitic stainless steel. As the austenitic stainless steel, for example, SUS316L is preferable.

In the middle stage (4th to 8th stages) of the second heat transfer tube 31, the raw tube 31a1 of the straight portion 31a is made of carbon steel such as STB340. On the other hand, in the middle stage of the second heat transfer tube 31, the fins 31a2 of the straight portion 31a are made of austenitic stainless steel such as SUS316L. In the middle stage of the second heat transfer tube 31, the upper curved portion 31b and the lower curved portion 31c are made of carbon steel such as STB340.

Furthermore, at the downstream stage (9th to 12th stages) of the second heat transfer tube 31, the raw tube 31a1 of the straight portion 31a is made of carbon steel such as STB340. On the other hand, at the downstream stage of the second heat transfer tube 31, the fins 31a2 of the straight portion 31a are made of carbon steel such as S-TEN1. Further, in the downstream stage of the second heat transfer tube 31, the upper curved portion 31b and the lower curved portion 31c are made of carbon steel such as STB340.

Since the heat medium flows into the high-temperature heating section 11 from the high-temperature preheating section 13, the temperature of the heat medium is medium, and since the exhaust gas G flows last, the corrosion environment is the best. Therefore, the first heat transfer tube 21 is a finned tube, and 14 straight portions 21a are arranged. In the high-temperature heating section 11, the raw tube 21a1 of the straight portion 21a is made of carbon steel such as STB340. On the other hand, in the first heat transfer tube 21, the fins 21a2 of the straight portion 21a are made of carbon steel such as S-TEN1. In the first heat transfer tube 21, the upper curved portion 21b and the lower curved portion 21c are made of carbon steel such as STB340.

In recent years, in the flue gas treatment apparatus 100 (see FIG. 1), the amount of flue gas to be treated has increased, and the temperature of the flue gas has also risen. However, since the exhaust gas contains mist containing corrosive impurities downstream of the desulfurization device 104, early corrosion of the heat transfer tubes used in the reheating device 105 poses a problem. Further, the reheating device 105 is required to have improved durability. In order to suppress early corrosion of the heat transfer tubes, it is conceivable to form the heat transfer tubes from a highly corrosion-resistant material. However, if the heat transfer tubes are made of a highly corrosion-resistant material, the material cost will increase.

Therefore, in the present embodiment, the base tube 13a1 of the third heat transfer tube 41 is made of duplex stainless steel in the high-temperature preheating section 13 where the corrosive environment is the worst. SUS329J4L is particularly suitable as the duplex stainless steel.

Further, since the low-temperature heating section 12 is arranged between the high-temperature preheating section 13 with the worst corrosive environment and the high-temperature heating section 11 with the best corrosive environment, the corrosive environment differs depending on the direction in which the exhaust gas G escapes. Therefore, the tube group composed of the plurality of second heat transfer tubes 31 constituting the low-temperature heating section 12 is divided into the first tube group constituting the upstream stage, the second tube group constituting the midstream stage, and the downstream stage. The second heat transfer tubes 31 in each tube group are made of different materials for the base tubes 31a1 and the fins 31a2.

In the low-temperature heating section 12, the second heat transfer tubes 31 of the first tube group are made of a material having higher corrosion resistance in the base tube 31a1 than in the fins 31a2. Further, in the second heat transfer tubes 31 of the second tube group, the fins 31a2 are made of a material having higher corrosion resistance than the base tube 31a1. Further, the fins 31a2 of the second heat transfer tubes 31 in the third tube group are made of a material having lower corrosion resistance than the fins 31a2 of the second heat transfer tubes 31 in the second tube group. In the second heat transfer tubes 31 of the third tube group, the fins 31a2 are made of a material having higher corrosion resistance than the base tube 31a1.

Specifically, as described above, in the second heat transfer tubes 31 of the first tube group, the mother tubes 31a1 are made of duplex stainless steel, and the fins 31a2 are made of austenitic stainless steel. In the second heat transfer tubes 31 of the second tube group, the raw tubes 31a1 are made of carbon steel, and in the second heat transfer tubes 31 of the second tube group, the fins 31a2 are made of austenitic stainless steel.

Corrosion such as rust occurs and progresses in general steel materials in a corrosive environment. On the other hand, stainless steel or the like suppresses the progress of corrosion by forming an extremely thin corrosion film on the surface. Cracks occur in steel materials due to the interaction of tensile stress and corrosive environment, and the cracks progress over time. Such a phenomenon is called stress corrosion cracking (SCC). Here, corrosion resistance can be rephrased as SCC resistance.

That is, in the low-temperature heating unit 12, the corrosion resistance of the base pipes 31a1 of the second heat transfer pipes 31 of the first pipe group, which is not in a corrosive environment, is made higher than that of the fins 31a2 in consideration of water leakage due to corrosion of the base pipes 31a1. On the other hand, the second heat transfer tubes 31 of the second tube group, which has a better corrosive environment than the first tube group, have higher corrosion resistance of the fins 31a2 than the mother tubes 31a1, considering the heat transfer of the fins 31a2 from water leakage due to corrosion of the mother tubes 31a1. do. Further, the fins 31a2 of the second heat transfer tubes 31 of the third tube group, which have a better corrosive environment than the first tube group and the second tube group, have lower corrosion resistance than the fins 31a2 of the second heat transfer tubes 31 of the second tube group. In the second heat transfer tubes 31 of the third tube group, the corrosion resistance of the fins 31a2 is made higher than that of the base tubes 31a1.

[Configuration of high-temperature preheating section]
7 is a schematic side view showing the high temperature preheating section, and FIG. 8 is a schematic front view showing the high temperature preheating section. In the following description, the vertical direction is the Z direction, the flow direction of the exhaust gas G is the horizontal direction orthogonal to the Z direction, and the width of the flow of the exhaust gas G is the horizontal direction orthogonal to the Z direction and the X direction. The direction will be described as the Y direction.

As shown in FIGS. 7 and 8 , the high temperature preheating section 13 has a third bundle 53 . A third casing 56 is arranged on the outside of the third bundle 53 . The third casing 56 has multiple first support members 61 and multiple second support members 62 . Four first support members 61 are arranged along the Z direction, which is the vertical direction, so as to face the third heat transfer tubes 41 on both sides of the first header 42 and the second header 43 in the Y direction, which is the longitudinal direction. . The four first support members 61 have a plate shape elongated in the Z direction. The two first support members 61 are arranged on one side of the first header 42 and the second header 43 in the Y direction, and their upper ends are fixed to the lower portions of the first header 42 and the second header 43 on the one end side. be. The two first support members 61 are spaced apart in the X direction and connected by connecting members 63 at a plurality of positions in the Z direction. Also, the two first support members 61 are covered with a cover (not shown) in the X direction.

The two first support members 61 are arranged on the other side of the first header 42 and the second header 43 in the Y direction, and the upper ends of the two first support members 61 fixed to The two first support members 61 are spaced apart in the X direction and connected by connecting members 63 at a plurality of positions in the Z direction. Also, the two first support members 61 are covered with a cover (not shown) in the X direction.

The second support member 62 is arranged on one side of the first header 42 and the second header 43 in the Y direction, and on the other side of the first header 42 and the second header 43 in the Y direction. The first supporting member 61 is connected. The first support members 61 are arranged along the Y direction, and are arranged in plurality at intervals in the X direction. The second support member 62 connects the pair of first support members 61 on the upstream side and the downstream side in the flow direction of the exhaust gas G (X direction). Therefore, the third casing 56 has a frame shape with openings on the upstream side and the downstream side in the flow direction of the exhaust gas G. As shown in FIG.

Further, the duct casing 60 is provided with a pair of frame beams 64 along the Y direction outside each of the first support members 61 in the third casing 56 . Both ends of the first header 42 and the second header 43 in the Y direction of the third bundle 53 are placed on a pair of structural beams 64 to be suspended and supported.

The first header 42 and the second header 43 are connected by horizontal connecting flanges 65 along the X and Y directions. One side of the first header 42 in the X direction and one side of the second header 43 in the X direction are connected by a connecting flange 65 . The first header 42 is fixed to the other side in the X direction with a horizontal mounting flange 66a along the X and Y directions. A horizontal mounting flange 66b extending in the X and Y directions is fixed to the other side of the second header 43 in the X direction.

The duct casing 60 has a mounting opening 60b formed at a predetermined position of the upper wall portion 60a. The third bundle 53 is inserted inside the duct casing 60 through the mounting opening 60b. In the third bundle 53, the Y-direction ends of the first header 42 and the second header 43 are welded to the inner periphery of the mounting opening 60b, and the connecting flange 65 and the mounting flanges 66a, 66a and 66a 66b is welded to the inner circumference of the mounting opening 60b.

In this case, the first header 42 and the second header 43 have a cylindrical shape, and a connecting flange 65 and mounting flanges 66a and 66b are fixed at intermediate positions in the Z direction. The connecting flange 65 and the mounting flanges 66a and 66b may be fixed to the top or bottom of the first header 42 and the second header 43 in the Z direction. Therefore, the lower part of the first header 42 and the second header 43 is positioned in the exhaust gas passage 121c inside the duct casing 60, and the upper part is exposed outside the duct casing 60 and is not positioned in the exhaust gas passage 121c.

A flange joint 44 is fixed to the top of the first header 42 , and a flange joint 45 is fixed to the top of the second header 43 . The flange joint 44 has a cylindrical portion 44 a and a flange portion 44 b , and the cylindrical portion 44 a communicates with the inside of the first header 42 . The flange joint 45 has a cylindrical portion 45 a and a flange portion 45 b , and the cylindrical portion 45 a communicates with the inside of the second header 43 . The second heat medium circulation line L12 is configured by piping and has a flange joint at the end. The piping of the second heat medium circulation line L12 has a flange joint fastened to the flange joint 45 of the second header 43 by bolts 45c. Also, the first connection line L21 is configured by a pipe and has a flange joint at its end. The piping of the first connection line L21 has a flange joint fastened to the flange joint 44 of the first header 42 by bolts 44c.

Moreover, the first header 42 and the second header 43 are fixed with hangers 67 at one end portion and the other step portion in the Y direction, respectively. The hanger 67 is fixed to the first header 42 and the second header 43 and the connecting flange 65 at its lower end on one end side of the first header 42 and the second header 43 in the Y direction. The lower end of the hanger 67 is fixed to the first header 42 and the second header 43 and the connection flange 65 on the other end side of the first header 42 and the second header 43 in the Y direction.

Although the configuration of the third bundle 53 of the high-temperature preheating section 13 has been described here, the first bundle 51 of the high-temperature heating section 11 and the second bundle 52 of the low-temperature heating section 12 are also different except for the number of stages of the heat transfer tubes. has almost the same configuration.

[Double tube expansion structure]
9 is a cross-sectional view showing the relationship between the header and the heat transfer tubes before connection, and FIG. 10 is a cross-sectional view showing the connection portion between the header and the heat transfer tubes after connection.

The third bundle 53 of the high temperature preheating section 13 has a plurality of third heat transfer tubes 41 . Each longitudinal end of the third heat transfer tube 41 is fixed to the first header 42 and the second header 43 . At this time, each end of the third heat transfer tube 41 is fixed to the first header 42 and the second header 43 by tube expansion. The connection structure between each end of the third heat transfer tube 41 and the first header 42 and the second header 43 is substantially the same. The connection structure will be described, and the description of the connection structure between the other end portion of the third heat transfer tube 41 and the second header 43 will be omitted.

As shown in FIG. 9, one end of the third heat transfer tube 41 is connected to the first header 42 by double expansion. The first header 42 has a connecting hole 42a at its lower portion, and the third heat transfer tube 41 has an enlarged tube portion 46 at its upper end portion. The third heat transfer tubes 41 are connected to the connecting holes 42 a of the first header 42 by the expanded tube portions 46 .

That is, the first header 42 has a horizontal cylindrical shape, and a connecting hole 42a is formed along the Z direction at the bottom in the Z direction. The connecting hole 42a has a cylindrical shape, and a plurality of (two in this embodiment) grooves 42b and 42c are formed on the inner peripheral surface. The plurality of grooves 42b and 42c form a ring shape continuous in the circumferential direction of the connecting hole 42a and have the same shape. The plurality of grooves 42b and 42c are spaced apart in the axial direction of the connecting hole 42a, that is, in the Z direction. The first groove portion 42b is formed on the inner peripheral surface side of the first header 42 with respect to the center of the first header 42 in the thickness direction, and the second groove portion 42c is formed on the center of the first header 42 in the thickness direction. On the other hand, it is formed on the outer peripheral surface side of the first header 42 .

Here, in the grooves 42b and 42c, lengths G1 and G2 in the axial direction (Z direction) of the connecting hole 42a are shorter than the length S1 of the interval between the grooves 42b and 42c. In addition, the axial lengths G1 and G2 of the connecting hole 42a of the grooves 42b and 42c are shorter than the length S1 of the gap between the grooves 42b and 42c and the inner surface of the first header 42 . The axial lengths G1 and G2 of the connecting hole 42a of the grooves 42b and 42c are shorter than the distance S2 between the grooves 42b and 42c and the outer surface of the first header 42 . The interval length S0, the interval length S1, and the interval length S2 are the same length. The axial lengths G1 and G2 of the connecting hole 42a of the grooves 42b and 42c are 0.9 to 1.1 times the thickness of the third heat transfer tube 41 .

Also, the first groove portion 42b forms a concave shape with respect to the inner peripheral surface of the connecting hole 42a. The first groove portion 42b includes a bottom surface 42b1 parallel to the axial direction of the connecting hole 42a, a pair of side surfaces 42b2 and 42b3 parallel to the radial direction of the connecting hole 42a, and a pair of grooves connecting the bottom surface 42b1 and the pair of side surfaces 42b2 and 42b3. curved surfaces 42b4 and 42b5. The second groove portion 42c also has the same shape as the first groove portion 42b.

The third heat transfer tube 41 has an outer diameter slightly smaller than the inner diameter of the connecting hole 42 a of the first header 42 . One end of the third heat transfer tube 41 is inserted into the connecting hole 42a. At this time, it is preferable that the end surface of the third heat transfer tube 41 is continuous with the inner peripheral surface of the first header 42 without a step. Here, in the first header 42 , the grooves 42 b and 42 c of the connecting hole 42 a are covered with the outer peripheral surface of the third heat transfer tube 41 . In this state, a tube expansion tool (not shown) is inserted into the third heat transfer tube 41 to position the pressurizing portion inside the end of the third heat transfer tube 41 inserted into the connecting hole 42a. Here, the enlarged diameter portion 46 is formed at the end of the third heat transfer tube 41 by increasing the diameter of the end of the third heat transfer tube 41 with the pressurizing portion.

As shown in FIG. 10, the third heat transfer tube 41 has a part of its end projecting outward, and projecting portions 46a and 46b as the enlarged diameter portion 46 at positions facing the groove portions 42b and 42c of the connecting hole 42a. is formed. That is, the portion of the third heat transfer tube 41 facing the first groove portion 42b expands outward to form a first protrusion 46a that engages with the first groove portion 42b. In addition, the third heat transfer tube 41 expands outward at the end facing the second groove 42c to form a second protrusion 46b that engages with the second groove 42c. The first protrusion 46a and the second protrusion 46b have substantially the same shape as the first groove 42b and the second groove 42c. The third heat transfer tube 41 is attached to the first header 42 by engaging the first protrusion 46a and the second protrusion 46b formed at the end with the first groove 42b and the second groove 42c of the connecting hole 42a. concatenated. After that, the ends of the third heat transfer tubes 41 are seal-welded 42 d to the inner peripheral surface of the first header 42 .

Although two grooves 42b and 42c are provided in the connecting hole 42a of the first header 42, three or more grooves may be provided. Further, the grooves 42b and 42c formed in the connecting hole 42a of the first header 42 and the projections 46a and 46b formed at the end of the third heat transfer tube 41 are formed in a ring shape continuous in the circumferential direction. It may have a ring shape that is intermittent in the circumferential direction, or it may not have a ring shape.

Although the double tube expansion structure of the third heat transfer tube 41 has been described here with the third bundle 53 of the high temperature preheating section 13, the first bundle 51 of the high temperature heating section 11 and the second bundle of the low temperature heating section 12 In 52, the first heat transfer tube 21 and the second heat transfer tube 31 have substantially the same double expanded tube structure.

[Connection structure of heat transfer tubes]
11 is a cross-sectional view showing upper end portions of heat transfer tubes connected to a header, and FIG. 12 is a cross-sectional view showing connecting portions of lower end portions of adjacent heat transfer tubes.

As shown in FIG. 11 , the third heat transfer tubes 41 are fixed to the first header 42 at one end (upper end) in the longitudinal direction (Z direction) by tube expansion. In this case, the third heat transfer tube 41 is a bare tube without fins and is made of duplex stainless steel such as SUS329J4L. On the other hand, the first header 42 is made of carbon steel. The connection between the third heat transfer tube 41 made of duplex stainless steel and the first header 42 made of carbon steel is dissimilar material connection.

Therefore, the third heat transfer tube 41 has a straight portion (heat transfer tube main body) 41a and a connecting portion (connecting pipe) 41d provided at the upper end of the straight portion 41a, and the straight portion 41a is made of duplex stainless steel, The connecting portion 41d is made of the same carbon steel as the first header 42, and the straight portion 41a made of duplex stainless steel and the connecting portion 41d made of carbon steel are connected by dissimilar material welding. Then, the outer side of the welded portion 71 between the linear portion 41a and the connecting portion 41d is covered with the covering portion 72. As shown in FIG.

The connecting portion 41d is a cylindrical stub whose upper end portion is directly connected to the first header 42, and is made of carbon steel. That is, the connecting portion 41d is connected to the first header 42 by the double tube expansion structure at the upper end portion. The straight portion 41a is made of duplex stainless steel (eg, SUS329J4L). The linear portion 41a and the connecting portion 41d have a cylindrical shape with the same outer diameter and inner diameter. The upper end surface of the straight portion 41a and the lower end surface of the connecting portion 41d are connected by welding while being in contact with each other. In this case, the upper end surface of the straight portion 41a and the lower end surface of the connecting portion 41d are welded all around while being in direct contact with each other without interposing an alloy material or the like.

The covering portion 72 protects the welded portion 71 between the straight portion 41a and the connecting portion 41d from the surrounding corrosive environment. The covering portion 72 covers the entire circumference of the welding portion 71 without gaps. The covering portion 72 is a lining, and in order to protect the outer surface of the welding portion 71 from potential difference corrosion, the outer surface of the welding portion 71 is covered with a predetermined thickness of a material different from that of the linear portion 41a and the connecting portion 41d. be. A method of providing the lining as the covering portion 72 is, for example, coating. Examples of materials for the lining include corrosion-resistant FRP (reinforced plastic), resin (eg, HF281 manufactured by Oji Rubber & Chemicals Co., Ltd.), rubber sheet (hard rubber, chloroprene, etc.), glass, and fluororesin.

The covering portion 72 covers not only the welded portion 71 between the straight portion 41a and the connecting portion 41d, but also covers a predetermined length from the welded portion 71 to the straight portion 41a, and also covers a predetermined length from the welded portion 71 to the connecting portion 41d. , for example, the connecting portion between the connecting portion 41 d and the first header 42 . The thickness of the coating is preferably 400 μm or more.

The upper end portions of adjacent third heat transfer tubes 41 are connected by upper curved portions 41b, and the lower end portions thereof are connected by lower curved portions 41c. At this time, when the straight portion 41a and the upper curved portion 41b are made of different materials, and when the straight portion 41a and the lower curved portion 41c are made of different materials, the welded portion between the straight portion 41a and the upper curved portion 41b, and It is preferable to provide a covering portion for the welded portion between the straight portion 41a and the lower curved portion 41c.

As shown in FIG. 12, the third heat transfer tube 41 has a straight portion 41a and a lower curved portion 41c provided at the lower end of the straight portion 41a, and the straight portion 41a and the lower curved portion 41c are made of different materials, Connect by dissimilar material welding. At this time, the outer side of the welded portion 73 between the straight portion 41 a and the lower curved portion 41 c is covered with the covering portion 74 . The straight portion 41a and the lower curved portion 41c have a cylindrical shape with the same outer diameter and inner diameter. The lower end surface of the straight portion 41a and the upper end surface of the lower curved portion 41c are connected by welding while being in contact with each other.

The covering portion 74 protects the welded portion 73 between the straight portion 41a and the lower curved portion 41c from the surrounding corrosive environment. The covering portion 74 covers the entire circumference of the welding portion 71 without gaps. The covering portion 74 is a lining, and in order to protect the outer surface of the welding portion 71 from potential difference corrosion, the outer surface of the welding portion 73 is covered with a predetermined thickness of a material different from that of the straight portion 41a and the lower curved portion 41c. is.

In the third heat transfer tube 41, mainly only the linear portion 41a is the heat transfer area range, and the area above and below the linear portion 41a in the Z direction is the non-heat transfer area. That is, the third bundle 53 has an exhaust gas passage 121c defined by the third casing 56, and the upper curved portion 41b, the lower curved portion 41c, and the connecting portion 41d of the third heat transfer tube 41 extend outward from the exhaust gas passage 121c. placed. Therefore, a coating portion 72 provided at a welded portion 71 between the straight portion 41a and the connecting portion 41d, a welded portion (not shown) between the straight portion 41a and the upper curved portion 41b, and a welded portion between the straight portion 41a and the lower curved portion 41c. The welded portion 73 is positioned outside the exhaust gas passage 121c. Even if the coating portions 72 and 74 are provided on the welded portions 71 and 73, the heat transfer performance of the third heat transfer tube 41 is hardly affected.

Although the connection structure of the third heat transfer tubes 41 has been described here with respect to the third bundle 53 of the high-temperature preheating section 13, the first bundle 51 of the high-temperature heating section 11 and the second bundle 52 of the low-temperature heating section 12 are also , the portions of the heat transfer tubes 21 and 31 that require dissimilar material welding have substantially the same connecting structure.

[Header maintenance structure]
13 is a cross-sectional view of the periphery of the header showing the relationship between the flange joint and the heat transfer tubes, and FIG. 14 is a cross-sectional view of the periphery of the header showing the relationship between the flange joint and the heat transfer tubes.

As shown in FIGS. 13 and 14 , in the third bundle 53 , maintenance can be performed on connecting portions of the plurality of third heat transfer tubes 41 from the first header 42 and the second header 43 . In this case, since the first header 42 and the second header 43 have the same maintenance structure for the connecting portions of the plurality of third heat transfer tubes 41, the maintenance structure of the first header 42 will be described, and the maintenance structure of the second header 43 will be described. A description of the maintenance structure is omitted.

The first header 42 has a flange joint 44 on the top thereof, to which the flange joint of the pipe of the first connection line L21 is fastened with bolts 44c. Upper ends of straight portions 41a of the plurality of third heat transfer tubes 41 are fixed to the plurality of connecting holes 42a in the lower portion of the first header 42, respectively. The first header 42 is provided with connecting portions 81 between the connecting holes 42a and the straight portions 41a of the third heat transfer tubes 41 at intervals in the Y direction, which is the longitudinal direction.

The first header 42 is provided with a plurality of working holes 82 in its upper portion, and the plurality of working holes 82 are provided with a plurality of plugs 83, respectively, and can be opened and closed. A plurality of working holes 82 are provided at positions other than the flange joint 44 at intervals in the Y direction, which is the longitudinal direction. In the first header 42, the plurality of working holes 82 and the plurality of connecting portions 81 face each other in the Z direction. The plurality of plugs 83 can be attached to and detached from the plurality of working holes 82 by screws, for example.

Therefore, by removing the plug 83 from the work hole 82 of the first header 42 , the worker can access the connecting portion 81 of the third heat transfer tube 41 through the work hole 82 using a repair jig.

In the high-temperature preheating section 13 , the exhaust gas G contacts the plurality of third heat transfer tubes 41 in the third bundle 51 . Then, the third heat transfer tube 41 may be corroded and damaged due to long-term use, and the heat medium may leak. Therefore, for example, a leak inspection of the plurality of third heat transfer tubes 41 is performed during a periodic inspection when the operation of the reheating device 105 is stopped. Then, in the leak test, the heat medium is discharged from the first header 42 , the second header 43 and the plurality of third heat transfer tubes 41 . Then, the plugs 83 are removed from the working holes 82 of the first header 42 and the second header 43 , and the leakage inspection is performed for each third heat transfer tube 41 .

A predetermined region of the third heat transfer tube 41 determined to have a leak in the leak inspection is isolated and made unusable. That is, for the third heat transfer tube 41 having a leak, the operator uses a tool (not shown) to fix a stopcock from the work hole 82 of the first header 42 to the connecting portion 81 of the third heat transfer tube 41, A plug is fixed to the connecting portion of the third heat transfer tube 41 through the working hole of the second header 43 .

The work hole 82 and the plug 83 are not provided in the portion of the first header 42 where the flange joint 44 is provided. Therefore, by removing the flange joint of the pipe of the first connection line L21 from the flange joint 44, the worker can remove the flange joint 44 The connection portion 81 of the third heat transfer tube 41 can be accessed from the .

Although the maintenance structure of the third bundle 53 of the high-temperature preheating section 13 has been described here, the first bundle 51 of the high-temperature heating section 11 and the second bundle 52 of the low-temperature heating section 12 also have the same maintenance structure. there is

[Hydrofilling method of heat transfer tubes]
FIG. 15 is a schematic diagram showing the relationship between the header and the heat transfer tubes in the high temperature preheating section, FIG. 16 is a schematic diagram showing the state of water filling in the high temperature preheating section, and FIG. is a schematic cross-sectional view of.

As described above, the reheating device 105 discharges the heat medium from the high-temperature heating section 11, the low-temperature heating section 12, and the high-temperature preheating section 13 during the periodic inspection. Then, when the periodic inspection is finished, the heat medium is supplied from the high temperature heating section 11, the low temperature heating section 12, and the high temperature preheating section 13, and the water filling work is carried out. In the reheating device 105, the heat medium flows through the high temperature preheating section 13, the high temperature heating section 11, and the low temperature heating section 12 in this order. 12 are supplied in order.

For example, as shown in FIG. 15 , the high-temperature preheating section 13 is configured by connecting a plurality of third heat transfer tubes 41 between a first header 42 and a second header 43 . The second header 43 has a flange joint 45 for supplying the heat medium located at one end in the longitudinal direction, and the first header 42 has a flange joint 44 for discharging the heat medium located at the other longitudinal end. . When the heat medium is supplied to the flange joint 45 of the second header 43, the heat medium flows longitudinally through the second header 43 and into the third heat transfer tubes 41 in sequence. Then, the heat medium reaches the first header 42 via the plurality of third heat transfer tubes 41, and the water filling is completed.

However, since the heat medium supplied to the second header 43 flows in the longitudinal direction of the second header 43 and then sequentially flows into each third heat transfer tube 41, each third heat transfer tube 41 is supplied to the end portion. The pressure of the heat medium fluctuates. Then, among the plurality of third heat transfer tubes 41 , it becomes difficult for the heat medium to reach the first header 42 in the third heat transfer tube 41 having a large flow resistance of the heat medium. For example, as shown in FIG. 16 , the heat medium is supplied from the flange joint 45 to the second header 43 , flows through the second header 43 , and then flows into the third heat transfer tubes 41 . At this time, since the straight portion 41a of the third heat transfer tube 41 is arranged along the vertical direction (the Z direction), even if the supply pressure of the heat medium is low, the heat medium flows through the straight portion 41a and the lower curved portion. It flows to the portion 41c. However, the heat medium that has flowed to the lower curved portion 41c cannot move up the next straight portion 41a following the lower curved portion 41c, making it difficult to fill all the third heat transfer tubes 41 with water. Become.

Therefore, in the present embodiment, among the plurality of third heat transfer tubes 41, the work of the second header 43 is performed for the third heat transfer tube 41, which has a large resistance to the flow of the supply pressure of the heat medium and the supply of the heat medium is insufficient. The heat transfer medium is supplied directly through the holes. That is, the heat medium is directly supplied to the third heat transfer tubes 41 that are in short supply using a water-filling jig.

As shown in FIG. 17, the water filling jig 201 has a main body 202, a nozzle 203, and a hose 204. As shown in FIG. The main body 202 has an on-off valve inside, for example, and can be mounted on the upper portion of the second header 43 . A nozzle 203 is connected to the bottom of the body 202 . The tip of the nozzle 203 can be inserted into the upper end of the straight portion 41 a of the third heat transfer tube 41 . A hose 204 is connected to the upper portion of the main body 202 . The hose 204 is connected to a source of heat transfer medium (eg, a pump, etc.).

Therefore, the operator first removes the plug 83 (see FIG. 14) of the work hole 82 facing the connecting portion 81 of the third heat transfer tube 41 to which the heat medium is insufficiently supplied. Next, the water filling jig 201 is placed in the work hole 82 . Then, the tip of the nozzle 203 is inserted into the upper end of the straight portion 41 a of the third heat transfer tube 41 . Here, the heat medium is supplied from the tip of the nozzle 203 to the straight portion 41a of the third heat transfer tube 41 at a predetermined pressure. Then, the heat medium is supplied to the entire third heat transfer tubes 41 and reaches the first header 42 . When the heat medium is supplied to the entire area of the third heat transfer tube 41, the water filling jig 201 is removed and the work hole 82 is closed with the plug 83 to complete the work.

Although the water-filling operation for the high-temperature preheating section 13 has been described here, the water-filling work for the high-temperature heating section 11 and the low-temperature heating section 12 is the same.

[Configuration of guide member]
FIG. 18 is a schematic front view showing the main part of the high temperature preheating section, and FIG. 19 is a horizontal sectional view showing the main part of the high temperature preheating section.

As shown in FIGS. 18 and 19, in the third bundle 53 of the high-temperature preheating section 13, the linear portions 41a of the plurality of third heat transfer tubes 41 are arranged in a staggered manner. That is, the plurality of straight portions 41a-1 in the most upstream row (first row) of the plurality of third heat transfer tubes 41 are closer to one side in the Y direction (right side in FIG. 19), and the second row from the most upstream. The plurality of linear portions 41a-2 of 1 are closer to the other side in the Y direction (the left side in FIG. 19), and the plurality of linear portions 41a-3 in the third row from the most upstream are closer to the other side in the Y direction (the left side in FIG. 19). right side).

Then, the plurality of straight portions 41a-1 in the most upstream row (first row) of the plurality of third heat transfer tubes 41 are located on the other side in the Y direction (left side in FIG. 19), the first A large gap is formed with the support member 61 . This gap is larger than the gap between the linear portions 41a adjacent to each other in the Y direction. Then, the exhaust gas G flowing in the X direction flows into the gap between the first support member 61 having a small resistance and the straight portion 41a-1 in the most upstream row, thereby reducing the heat exchange efficiency.

Therefore, a guide member 91 is provided to block the gap between the first support member 61 and the most upstream linear portion 41a-1 and to guide the exhaust gas G toward the linear portion 41a-1. The guide member 91 is located on the most upstream side in the flow direction of the exhaust gas G from the plurality of third heat transfer tubes 41, and on the straight portion 41a-1 side of the most upstream row of the third heat transfer tubes 41 from the third casing 56 (duct casing 60). extended to

The guide member 91 has a plate-shaped guide plate 92 . The guide plate 92 is arranged along the Y direction (arrangement direction), which is the in-plane direction facing the flow direction (X direction) of the exhaust gas G, and the Z direction, which is the vertical direction. One end of the guide plate 92 in the Y direction is fixed to the first support member 61, and the other end in the Y direction extends toward the most upstream linear portion 41a-1. The guide plate 92 has its upper end in the Z direction fixed to the third support member 66 and its other end in the Z direction also fixed to the third support member 66 . The guide plate 92 is longer in the Z direction than in the Y direction. The guide plate 92 preferably has an aspect ratio of, for example, 50:550 to 50:1400.

The guide plate 92 faces the flow of the exhaust gas G at the surface portion 92a. The guide plate 92 is fixed by welding, for example, so that the back surface portion 92b at one end in the Y direction is in contact with the front surface portion 61a of the first support member 61 . The guide plate 92 has a length L1 in the Y direction from the third casing 56 that is shorter than or equal to a length L2 from the third casing 56 to the center of the most upstream linear portion 41a-1 adjacent in the Y direction. become. That is, when the third bundle 53 is viewed from the upstream side in the flow direction of the exhaust gas G, the guide plate 92 and the most upstream linear portion 41a-1 may overlap.

Further, the distance L3 between the guide plate 92 and the most upstream linear portion 41a-1 in the flow direction of the exhaust gas G is 0 mm to 50 mm.

The guide member 91 (guide plate 92) is arranged in the flow direction of the exhaust gas G from the first support member 61 and the straight line portion 41a-1 so as to close the gap between the first support member 61 and the straight line portion 41a-1 in the most upstream row. placed upstream of The exhaust gas G flowing into the third bundle 53 of the high-temperature preheating section 13 contacts the plurality of third heat transfer tubes 41 . At this time, on the other side in the Y direction, the exhaust gas G flowing on the side of the first support member 61 abuts against the guide member 91 and is guided toward the straight portion 41 a - 1 , and contacts the plurality of third heat transfer tubes 41 . That is, although a large gap is formed between the first support member 61 and the most upstream linear portion 41a-1, the guide member 91 is positioned upstream of this gap, so that the exhaust gas G passes through this gap. flow is suppressed. Therefore, deterioration in heat exchange efficiency due to the plurality of third heat transfer tubes 41 is suppressed.

In the above description, the guide member 91 is fixed to the third casing 56 and extends from the third casing 56 toward the straight portion 41a-1 of the most upstream row of the third heat transfer tubes 41. It is not limited. That is, the guide member 91 may be fixed to the duct casing 60 and extended from the duct casing 60 toward the straight portion 41 a - 1 of the most upstream row of the third heat transfer tubes 41 . That is, when the third bundle 53 is fixed to the duct casing 60, the duct casing 60 and the third casing 56 form a substantially integrated structure. Therefore, the guide member 91 may be fixed to either the third bundle 53 or the duct casing 60 .

Further, the guide member 91 is positioned closest to the third casing 56 (duct casing 60) of the straight portions 41a-1 of the third heat transfer tubes positioned in the most upstream row in the flow direction of the exhaust gas G in the high-temperature preheating section 13. It is provided only for the straight portion 41a-1 of the nearest third heat transfer tube. With respect to the straight portion 41a of the third heat transfer tube closest to the third casing 56 (duct casing 60) among the straight portions 41a of the third heat transfer tube positioned on the second and subsequent rows from the most upstream in the flow direction of the exhaust gas G The guide member 91 need not be provided.

Further, in the high-temperature heating section 11 and the low-temperature heating section 12, the heat transfer tubes 21 and 31 are arranged not in a zigzag pattern, but in a grid pattern, so that there is no need to provide a guide member. However, when the heat transfer tubes 21 and 31 are arranged in a staggered manner in the high temperature heating section 11 and the low temperature heating section 12, a guide member may be provided.

[Configuration of heat transfer tube supporting member]
FIG. 20 is a vertical cross-sectional view showing support portions for the heat transfer tubes in the high-temperature preheating section, and FIG. 21 is a horizontal cross-sectional view showing support portions for the heat transfer tubes in the high-temperature preheating section.

As shown in FIGS. 20 and 21, the third bundle 53 has a third casing 56 arranged outside, and the upper end of the third casing 56 is connected to the first header 42 and the second header 43 (see FIG. 8). Supported. The third casing 56 has a plurality of first support members 61 arranged on both sides in the Y direction and elongated in the Z direction, and a plurality of second support members 62 arranged on both sides in the X direction and elongated in the Y direction. The third casing 56 is configured by assembling a plurality of first support members 61 and a plurality of second support members 62 to form a frame shape.

A plurality of third heat transfer tubes 41 are suspended from the first header 42 and the second header 43 and arranged inside the third casing 56 . Since the longitudinal upper ends of the plurality of third heat transfer tubes 41 are connected to the first header 42 and the second header 43, they are cantilevered and unstable. Therefore, a plurality of support plates 96 that support the plurality of third heat transfer tubes 41 are arranged inside the third casing 56 .

The support plate 96 is supported by the first support member 61 and the second support member 62 that form the third casing 56 at its outer edge. The support plate 96 is a plate member that is horizontal in the X and Y directions and has a predetermined thickness. The support plate 96 is formed with a plurality of through holes 97 through which the straight portions 41a of the third heat transfer tubes 41 are inserted. The support plate 96 has a rectangular shape in a plan view, and a pair of outer edge portions 96a opposed in the X direction are fixed to the upper surface portion 62a of the second support member 62 in the Z direction. A pair of outer edge portions 96b of the support plate 96 facing each other in the Y direction are fixed to the inner wall portion 61b of the first support member 61 in the Y direction. That is, the support plate 96 is fixed by welding while the lower surface of the outer edge portion 96a is placed on the upper surface portion 62a of the second support member 62 . The support plate 96 is fixed by welding with the end surface of the outer edge portion 96 b in contact with the inner wall portion 61 b of the first support member 61 . The support plate 96 has a rectangular shape, and the length in the X direction and the Y direction is in the range of 2.5 m to 2.7 m.

Also, the support plate 96 is provided with a plurality of drain holes 98 adjacent to the plurality of through holes 97 . The plurality of drain holes 98 are smaller in diameter than the plurality of through holes 97 . Also, the plurality of drain holes 98 are formed at appropriate positions with respect to the support plate 96 .

A plurality of support plates 96 are arranged inside the third casing 56 at intervals in the Z direction. The plurality of support plates 96 have substantially the same shape. However, the support plates 96 adjacent in the Z direction are formed such that the positions of the through holes 97 are shifted by a predetermined distance in at least one of the X direction and the Y direction. That is, since the straight portion 41a of the third heat transfer tube 41 is inserted through the through hole 97, the inner diameter of the through hole 97 is slightly larger than the outer diameter of the straight portion 41a. When the through-holes 97 of the support plate 96 adjacent in the Z-direction are shifted in the X-direction or the Y-direction, the outer peripheral surface of the straight-line portion 41a of the third heat transfer tube 41 is inserted through the through-hole 97. It becomes easier to contact the inner peripheral surface of the hole 97 . Then, the linear portion 41 a of the third heat transfer tube 41 comes into contact with the through hole 97 , thereby suppressing vibration. It is preferable that the displacement amount (predetermined distance) between the through holes 97 of the support plates 96 adjacent in the Z direction is equal to or less than the difference between the inner diameter of the through holes 97 and the outer diameter of the linear portion 41a.

The support plate 96 has a pair of outer edge portions 96a that face each other in the X direction and is fixed to the upper surface portion 62a of the second support member 62 in the Z direction. The exhaust gas G flowing into the third bundle 53 of the high-temperature preheating section 13 contains corrosive impurity-containing mist and the like. When the exhaust gas G collides with the plurality of third heat transfer tubes 41 , it liquefies and falls, and accumulates on the support plate 96 . At this time, the corrosive impurity-containing fluid on the support plate 96 flows over the support plate 96 and falls over the second support member 62 from the outer edge portion 96a side. Also, the fluid containing corrosive impurities on the support plate 96 flows over the support plate 96 and drops from the drain holes 98 . Therefore, the corrosive impurity-containing fluid does not stay on the support plate 96, and corrosion of the support plate 96 is suppressed.

Although the third bundle 53 of the high-temperature preheating section 13 has been described here, the first bundle 51 of the high-temperature heating section 11 and the second bundle 52 of the low-temperature heating section 12 have the same configuration.

In the reheating device 105 of the present embodiment described above, the first bundle 51, the second bundle 52, and the third bundle 53 that constitute the high-temperature heating unit 11, the low-temperature heating unit 12, and the high-temperature preheating unit 13 are attached to the existing bundles. are interchangeable with respect to In a conventional reheating device, for example, a bundle forming a high-temperature preheating section is arranged inside a duct casing. In other words, conventionally, an inlet header, an outlet header, and a plurality of heat transfer tubes were arranged inside the duct casing. Therefore, in this embodiment, the existing bundle arranged inside the duct casing is taken out, and a new bundle of this embodiment is inserted and fixed.

A method for replacing the bundle in the high-temperature preheating section 13 will be described below. The same applies to the high-temperature heating section 11 and the low-temperature heating section 12 .

As shown in FIGS. 7 and 8, first, in the duct casing 60, the existing bundle arranged in the exhaust gas passage 121c is cut at a predetermined portion of the upper wall portion 60a facing upward, and attached to the upper wall portion 60a. An opening 60b is formed. Next, the existing bundle arranged in the exhaust gas passage 121c is lifted up and pulled out of the duct casing 60 through the mounting opening 60b. In addition, various pipes of the heat medium connected to the existing bundle are removed in advance.

Subsequently, the new third bundle 53 of this embodiment is lifted and moved above the mounting opening 60b. Then, by hanging the new third bundle 53, it is inserted into the exhaust gas passage 121c in the duct casing 60 from the mounting opening 60b. At this time, the headers 42 and 43 of the third bundle 53 are placed on the structural beams 64 of the duct casing 60 . Then, the position of the third bundle 53 is adjusted with respect to the duct casing 60 .

After that, the mounting opening 60b is closed by welding the headers 42, 43 of the third bundle 53 to the peripheral edge of the mounting opening 60b and connecting the mounting flanges 66a, 66b to the peripheral edge of the mounting opening 60b. Various pipes for the heat medium are connected to the headers 42 and 43 of the third bundle 53 .

[Action and effect of the present embodiment]
The bundle according to the first aspect includes a duct casing 60, a plurality of heat transfer tubes 21, 31, 41 arranged in a zigzag pattern inside the duct casing 60, and a plurality of heat transfer tubes 21, 31, 41 for exhaust gas G. and a guide member 91 extending from the duct casing 60 toward the heat transfer tubes 21, 31, 41 on the most upstream side in the flow direction.

According to the bundle according to the first aspect, the exhaust gas G flowing near the duct casing 60 is guided by the guide member 91 and flows toward the heat transfer tubes 21, 31, 41 on the most upstream side. Therefore, even if the heat transfer tubes 21, 31, 41 are arranged in a zigzag pattern and there are gaps between the duct casing 60 and the heat transfer tubes 21, 31, 41 on the most upstream side, the exhaust gas G does not flow through the gaps. is suppressed, and the heat exchange efficiency of the heat transfer tubes 21, 31, 41 can be improved.

The bundle according to the second aspect is the bundle according to the first aspect, and the guide member 91 has a plate shape and is arranged along an arrangement direction intersecting the flow direction of the exhaust gas G. As a result, the guide member 91 can be shaped like a plate because it only guides the exhaust gas G, and the structure can be simplified.

The bundle according to the third aspect is the bundle according to the first aspect or the second aspect, and further, the guide member 91 has a length in the arrangement direction from the duct casing 60 and is adjacent to the duct casing 60 in the arrangement direction. Shorter than the length up to the heat transfer tubes 21 , 31 , 41 . As a result, the guide member 91 causes the exhaust gas G to flow toward the heat transfer tubes 21, 31, 41, so that the heat exchange efficiency of the heat transfer tubes 21, 31, 41 can be further improved.

The bundle according to the fourth aspect is the bundle according to any one of the first to third aspects, and the guide member 91 has an aspect ratio of 50:550 to 50:1400. Thereby, the guide member 91 can be defined to have an appropriate size.

The bundle according to the fifth aspect is the bundle according to any one of the first aspect to the fourth aspect, and furthermore, the guide member 91 and the heat transfer tube 21 positioned most upstream in the flow direction of the exhaust gas G , 31 and 41 are from 0 mm to 50 mm. As a result, the guide member 91 causes the exhaust gas G to flow toward the heat transfer tubes 21 , 31 , 41 , thereby further improving the heat exchange efficiency of the heat transfer tubes 21 , 31 , 41 .

A bundle according to a sixth aspect is the bundle according to any one of the first aspect to the fifth aspect, and the guide member 91 is positioned on the most upstream side in the flow direction of the exhaust gas G. Of the heat pipes 21 , 31 , 41 , only the heat transfer pipes 21 , 31 , 41 closest to the duct casing 60 are provided. Thereby, the simplification of the structure can be achieved.

The heat exchanger according to the seventh aspect includes an exhaust gas passage 121c partitioned by a duct casing 60, and bundles 51, 52, 53 arranged in the exhaust gas passage 121c. As a result, the exhaust gas G flowing in the vicinity of the duct casing 60 is guided by the guide member 91 and flows toward the heat transfer tubes 21, 31, 41 on the most upstream side. Therefore, the exhaust gas G is suppressed from flowing into the gaps between the duct casing 60 and the heat transfer tubes 21, 31, 41 on the most upstream side, and the heat exchange efficiency of the heat transfer tubes 21, 31, 41 can be improved.

The flue gas treatment apparatus according to the eighth aspect includes a heat recovery device 101 that recovers part of the heat of the exhaust gas G, an electric dust collector 102 that removes dust contained in the exhaust gas G after heat recovery, and a dust collector. A desulfurization device 104 for removing sulfur oxides contained in the later exhaust gas G and a reheating device 105 for reheating the exhaust gas G after desulfurization are provided. As a result, in the reheating device 105, the exhaust gas G flowing in the vicinity of the duct casing 60 is guided by the guide member 91 and flows toward the heat transfer tubes 21, 31, 41 on the most upstream side. Therefore, the exhaust gas G is suppressed from flowing into the gaps between the duct casing 60 and the heat transfer tubes 21, 31, 41 on the most upstream side, and the heat exchange efficiency of the heat transfer tubes 21, 31, 41 can be improved.

The method for manufacturing a bundle according to the ninth aspect includes a guide member extending from the duct casing 60 toward the heat transfer tubes 21, 31, and 41 on the most upstream side in the flow direction of the exhaust gas G from the plurality of heat transfer tubes 21, 31, and 41. 91 is fixed by welding. As a result, the exhaust gas G flowing in the vicinity of the duct casing 60 is guided by the guide member 91 and flows toward the heat transfer tubes 21, 31, 41 on the most upstream side. Therefore, the exhaust gas G is suppressed from flowing into the gaps between the duct casing 60 and the heat transfer tubes 21, 31, 41 on the most upstream side, and the heat exchange efficiency of the heat transfer tubes 21, 31, 41 can be improved. Further, it is only necessary to fix the guide member 91 to the duct casing 60, so that the manufacturing work can be simplified.

In addition, in the embodiment described above, the reheating device 105 includes the high temperature heating section 11 , the low temperature heating section 12 and the high temperature preheating section 13 . In this case, the length and number of the first heat transfer tube 21, the second heat transfer tube 31, and the third heat transfer tube 41 may be appropriately set according to the usage pattern. Further, the reheating device 105 may be composed of the high temperature heating section 11 and the high temperature preheating section 13 .

Further, in the above-described embodiment, the reheating device 105 includes the first bundle 51, the second bundle 52, and the third bundle 53, the high-temperature heating unit 11 constitutes the first bundle 51, and the low-temperature heating unit 12 constitutes the third bundle. Although two bundles 52 are configured and the third bundle 53 is configured by the high-temperature preheating section 13, the configuration is not limited to this. For example, the low-temperature heating section 12 and the high-temperature preheating section 13 may be configured by a common bundle.

Further, in the above-described embodiment, the heat exchanger of the present invention is applied to the reheating device 105 of the flue gas treatment apparatus 100, but it may be applied to another heat exchanger.

11 high temperature heating section 12 low temperature heating section 13 high temperature preheating section 21 first heat transfer tube 22 first header 23 second header 24, 25 flange joint 31 second heat transfer tube 32 first header 33 second header 34, 35 flange joint 41 second 3 Heat Transfer Tubes 42 First Header 43 Second Header 44, 45 Flange Joint 46 Expanded Diameter Portion 51 First Bundle 52 Second Bundle 53 Third Bundle 54 First Casing 55 Second Casing 56 Third Casing 60 Duct Casing 61 First First Supporting member 62 Second supporting member 63 Connecting member 64 Frame beam 65 Connecting flange 66a, 66b Mounting flange 67 Hanging tool 71, 73 Welding part 72, 74 Coating part 81 Connecting part 82 Work hole 83 Plug 91 Guide member 92 Guide plate 96 Support Plate 97 Through hole 98 Drain hole 100 Flue gas treatment device 101, 101a, 101b Heat recovery device 102, 102a, 102b Electrostatic precipitator 103, 103a, 103b Air blower 104 Desulfurization device 105 Reheating device 106, 106a, 106b Air blower Apparatus 111 Boiler 112 Chimney 121a, 121b, 121c, 121d, 121e, 121f, 121g Exhaust gas passage 122 On-off valve 123 Mist eliminator 131 Circulation pump 132 Heater 133 Drain tank 134 On-off valve L11 First heat medium circulation line L12 Second heat medium circulation Line L13 Steam line L14 Steam drain line L21 First connection line L22 Second connection line G Exhaust gas W Heat medium

Claims (8)

a plurality of heat transfer tubes arranged in a zigzag pattern inside the duct casing ;
a bundle casing arranged outside the plurality of heat transfer tubes inside the duct casing;
a guide member extending from the bundle casing toward the heat transfer tubes on the most upstream side of the plurality of heat transfer tubes in the gas flow direction;
A heat exchanger with The guide member has a plate shape and is arranged along an arrangement direction that intersects the gas flow direction.
A heat exchanger according to claim 1. The guide member has a length from the duct casing in the arrangement direction that is shorter than a length from the duct casing to the heat transfer tube adjacent in the arrangement direction.
A heat exchanger according to claim 2. The guide member has an aspect ratio of 50:550 to 50:1400.
A heat exchanger according to claim 1. The distance between the guide member and the heat transfer tube positioned most upstream in the gas flow direction is 0 mm to 50 mm.
A heat exchanger according to claim 1. The guide member is provided only for the heat transfer tube closest to the duct casing, among the heat transfer tubes located on the most upstream side in the gas flow direction.
A heat exchanger according to claim 1. a heat recovery device that recovers part of the heat of the exhaust gas;
a dust collector for removing dust contained in the exhaust gas after heat recovery;
a desulfurization device for removing sulfur oxides contained in the exhaust gas after dust collection;
A reheater to which the heat exchanger according to claim 1 is applied for reheating the exhaust gas after desulfurization;
A flue gas treatment device. In a heat exchanger in which one longitudinal end of a plurality of heat transfer tubes is connected to a header and arranged inside a duct casing,
disposing a bundle casing outside the plurality of heat transfer tubes inside the duct casing;
A guide member extending from the bundle casing to the heat transfer tube side is fixed by welding to the most upstream side of the plurality of heat transfer tubes in the flow direction of the exhaust gas.
A method for manufacturing a heat exchanger .

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