Bundle and heat exchanger, and flue gas treatment device

Abstract

The bundle, heat exchanger, and flue gas treatment device are designed to be compact. [Solution] The system comprises an inlet header to which a heat transfer medium is supplied, an outlet header from which the heat transfer medium is discharged, and a plurality of heat transfer tubes formed by connecting the inlet header and the outlet header, and of the connection parts of the plurality of heat transfer tubes connected to the inlet header and the outlet header, at least the connection parts of the heat transfer tubes connected to the longitudinally furthest ends of the inlet header and the outlet header are connected offset toward the connection parts of the adjacent heat transfer tubes.

Description

[Technical Field]

[0001] The present disclosure relates to a bundle, a heat exchanger, and a flue gas treatment device. [Background technology]

[0002] Flue gas treatment equipment installed in thermal power plants and the like is composed of a heat recovery unit, an electrostatic precipitator, a desulfurization unit, a reheating unit, and other components. The soot and dust contained in the flue gas discharged from the boiler is removed by the electrostatic precipitator, and the sulfur dioxide gas contained in the flue gas is removed by the desulfurization unit. The heat recovery unit recovers heat from the flue gas. The reheating unit reheats the desulfurized flue gas using the heat recovered by the heat recovery unit, thereby suppressing the emission of white smoke.

[0003] A heat exchanger serving as a heat recovery device or a reheating device includes an inlet header, an outlet header, and a plurality of heat transfer tubes. One end of each of the heat transfer tubes is connected to the inlet header, and the other end is connected to the outlet header. A heat medium supplied to the inlet header flows through the heat transfer tubes and exchanges heat with exhaust gas flowing through an exhaust gas passage when it is discharged to the outlet header. An example of such a heat exchanger is described in Patent Document 1. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 7221437 Summary of the Invention [Problem to be solved by the invention]

[0005] The inlet header and outlet header are arranged vertically or horizontally, and the ends of the heat transfer tubes are connected to each other. The heat transfer tubes are arranged at equal intervals along the length of the inlet header and outlet header, with gaps between them. This means that the inlet header and outlet header must be longer than the length of the arrangement of the heat transfer tubes, which creates a problem of large size.

[0006] The present disclosure is intended to solve the above-mentioned problems, and aims to provide a bundle, a heat exchanger, and an exhaust gas treatment device that enable miniaturization of the device and improvement of heat exchange performance. [Means for solving the problem]

[0007] In order to achieve the above object, the bundle of the present disclosure comprises an inlet header to which a heat medium is supplied, an outlet header from which the heat medium is discharged, and a plurality of heat transfer tubes connecting the inlet header and the outlet header, and of the connection portions of the plurality of heat transfer tubes connected to the inlet header and the outlet header, at least the connection portions of the heat transfer tubes connected to the longitudinally furthest ends of the inlet header and the outlet header are connected offset toward the connection portions of the adjacent heat transfer tubes.

[0008] The heat exchanger of the present disclosure also includes a duct casing that forms an exhaust gas passage, and the bundle that is disposed inside the duct casing.

[0009] The flue gas treatment device of the present disclosure also includes a heat recovery device that recovers a portion of the heat of the exhaust gas, a dust collection device that removes soot and dust contained in the exhaust gas after heat recovery, a desulfurization device that removes sulfur oxides contained in the exhaust gas after dust collection, and a reheating device to which the heat exchanger is applied that reheats the exhaust gas after desulfurization. [Effects of the Invention]

[0010] According to the heat transfer tube, heat exchanger, and flue gas treatment device of the present disclosure, it is possible to reduce the size of the device and improve the heat exchange performance. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of the flue gas treatment device of this embodiment. [Figure 2] FIG. 2 is a schematic diagram showing the heat recovery device and the reheating device of this embodiment. [Figure 3]FIG. 3 is a schematic plan view showing the heat exchanger of this embodiment. [Figure 4] FIG. 4 is a schematic side view showing the heat exchanger of this embodiment. [Figure 5] FIG. 5 is a schematic side view showing the main part of the bundle of this embodiment. [Figure 6] FIG. 6 is a schematic side view showing the main part of a conventional bundle. [Figure 7] FIG. 7 is a cross-sectional view showing the upper part of the bundle of this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Preferred embodiments of the present disclosure will be described in detail below with reference to the drawings. Note that the present disclosure is not limited to these embodiments, and when there are multiple embodiments, the present disclosure also includes configurations that combine the embodiments. Furthermore, the components in the embodiments include those that can be easily imagined by a person skilled in the art, those that are substantially identical, and those that are within the so-called equivalent range.

[0013] [Smoke exhaust treatment device] FIG. 1 is a schematic diagram showing the configuration of the flue gas treatment device of this embodiment.

[0014] As shown in FIG. 1, the flue gas treatment device 100 removes harmful substances such as soot and sulfur oxides (SOx) contained in flue gas (flue gas) G discharged from a boiler 111 in various power plants, factories, etc., as the flue gas G is released from a chimney 112.

[0015] The flue gas treatment device 100 includes a heat recovery device 101, an electrostatic precipitator 102, a blower (induced draft fan) 103, a desulfurization device 104, a reheating device 105, and a blower (desulfurization fan) 106. The flue gas treatment device 100 includes a first treatment system that sends flue gas G discharged from a boiler 111 to a chimney 112 through the heat recovery device 101, the electrostatic precipitator 102, and the blower 103, and a second treatment system that sends flue gas G discharged from the boiler 111 to the chimney 112 through the heat recovery device 101, the electrostatic precipitator 102, the blower 103, the desulfurization device 104, the reheating device 105, and the blower (desulfurization fan) 106.

[0016] In the case of the first treatment system, the blower 103 is driven, causing the exhaust gas G discharged from the boiler 111 to pass through the heat recovery device 101 and the electrostatic precipitator 102 and be sent to the chimney 112. In the case of the second treatment system, the blowers 103 and 106 are driven, causing the exhaust gas G discharged from the boiler 111 to pass through the heat recovery device 101, the electrostatic precipitator 102, the desulfurization device 104, and the reheating device 105 and be sent to the chimney 112. The arrangement of the devices is not limited to the arrangement described above.

[0017] 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, while 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 merge into an exhaust gas passage 121c on the downstream side. The exhaust gas passage 121c branches into two exhaust gas passages 121d and 121e. The exhaust gas passage 121d constitutes part of the first treatment system, has an on-off valve 122 provided midway, and is connected to the chimney 112 on the downstream side.

[0018] The exhaust gas passage 121e constitutes a second treatment system, and is provided with a desulfurization device 104 and a reheating device 105. The exhaust gas passage 121e branches into two exhaust gas passages 121f and 121g on the downstream side. The exhaust gas passage 121f is provided with a blower 106a, and the exhaust gas passage 121g is provided with a blower 106b. The two exhaust gas passages 121f and 121g merge into an exhaust gas passage 121h on the downstream side. The exhaust gas passage 121d, which constitutes a part of the first treatment system, and the exhaust gas passage 121h, which constitutes a part of the second treatment system, merge into an exhaust gas passage 121i on the downstream side. The exhaust gas passage 121i is connected to the chimney 112.

[0019] The heat recovery device 101 (101a, 101b) recovers heat from the exhaust gas G (approximately 140°C) discharged from the boiler 111 by exchanging heat between the exhaust gas G and a heat medium (such as water). The exhaust gas G (approximately 90°C) whose heat has been recovered by the heat recovery device 101 is introduced into the electrostatic precipitator 102 (102a, 102b). The electrostatic precipitator 102 removes soot and dust from the exhaust gas G.

[0020] The flue gas G from which soot and dust have 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 flue gas G using limestone (CaCO3) and produces gypsum (CaSO4.2H2O) as a by-product. The desulfurization device 104 has a mist eliminator 123. The mist eliminator 123 removes mist from the flue gas G after desulfurization.

[0021] The flue gas G (approximately 50°C) desulfurized by the desulfurization device 104 is introduced into the reheating device 105, which is a gas-gas heater. The reheating device 105 reheats the flue gas G using heat recovered by the heat recovery device 101 during the process of circulating the heat medium between the reheating device 105 and 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. The first heat medium circulation line L11 is provided with a circulation pump 131. When the circulation pump 131 is driven, the heat medium from the reheating device 105 is returned to the heat recovery device 101 via the first heat medium circulation line L11. The second heat medium circulation line L12 is provided with a heater 132. The circulation pump 131 supplies the heat medium from the heat recovery device 101 to the reheating device 105 via the second heat medium circulation line L12. During this process, the heater 132 is operated as needed to heat the heat medium.

[0022] The temperature of the exhaust gas G drops as a result of being desulfurized in the desulfurization device 104, and if the temperature remains low, it will be difficult to diffuse and may turn into white smoke. The reheating device 105 reheats the exhaust gas G to raise its temperature (to about 90°C) for the purpose of diffusion and reducing white smoke, and then releases the exhaust gas G into the atmosphere from the chimney 112. Note that the temperature of the exhaust gas G described above is an example and is not limited thereto.

[0023] [Configuration of heat recovery equipment and reheating equipment] FIG. 2 is a schematic diagram showing the heat recovery device and the reheating device of this embodiment.

[0024] 2, the heat recovery unit 101 and the reheating unit 105 are complete countercurrent heat exchangers. However, the heat recovery unit 101 and the reheating unit 105 may be heat exchangers of other types, such as high-temperature preheating countercurrent type, high-temperature preheating parallel type, or medium-temperature preheating type.

[0025] The heat recovery device 101 includes a high-temperature heat recovery section 141, a medium-temperature heat recovery section 142, and a low-temperature heat recovery section 143. The high-temperature heat recovery section 141, the medium-temperature heat recovery section 142, and the low-temperature heat recovery section 143 are arranged in the exhaust gas passage 121a (121b). However, the heat recovery device 101 is not limited to this configuration. The heat recovery device 101 may be configured with one heat recovery section or multiple heat recovery sections.

[0026] The high-temperature heat recovery section 141 has a plurality of first heat transfer pipes 151. The first heat transfer pipes 151 are arranged in the exhaust gas passage 121a (121b) along the flow direction of the exhaust gas G. An end 151a of the first heat transfer pipe 151 located on the upstream side in the flow direction of the exhaust gas G is connected to a first header 152, and an end 151b located on the downstream side in the flow direction of the exhaust gas G is connected to a second header 153.

[0027] The medium-temperature heat recovery section 142 is arranged downstream of the high-temperature heat recovery section 141 in the flow direction of the exhaust gas G. The medium-temperature heat recovery section 142 has a plurality of second heat transfer pipes 154. The second heat transfer pipes 154 are arranged in the exhaust gas passage 121a (121b) along the flow direction of the exhaust gas G. An end 154a of the second heat transfer pipe 154 located on the upstream side in the flow direction of the exhaust gas G is connected to the first header 155, and an end 154b located on the downstream side in the flow direction of the exhaust gas G is connected to the second header 156.

[0028] The low-temperature heat recovery section 143 is arranged downstream of the medium-temperature heat recovery section 142 in the flow direction of the exhaust gas G. The low-temperature heat recovery section 143 has a plurality of third heat transfer pipes 157. The third heat transfer pipes 157 are arranged in the exhaust gas passage 121a (121b) along the flow direction of the exhaust gas G. An end 157a of the third heat transfer pipe 157 located on the upstream side in the flow direction of the exhaust gas G is connected to the first header 158, and an end 157b located on the downstream side in the flow direction of the exhaust gas G is connected to the second header 159.

[0029] The reheating device 105 includes a high-temperature heating section 161, a medium-temperature heating section 162, and a low-temperature heating section 163. The high-temperature heating section 161, the medium-temperature heating section 162, and the low-temperature heating section 163 are arranged in the exhaust gas passage 121e. The reheating device 105 is not limited to this configuration. The reheating device 105 may be configured with one heating section or multiple heating sections.

[0030] The high-temperature heating unit 161 has a plurality of first heat transfer pipes 171. The first heat transfer pipes 171 are arranged in the exhaust gas passage 121e along the flow direction of the exhaust gas G. An end 171a of the first heat transfer pipe 171 located downstream in the flow direction of the exhaust gas G is connected to a first header 172, and an end 171b located upstream in the flow direction of the exhaust gas G is connected to a second header 173.

[0031] The medium-temperature heating section 162 is arranged upstream of the high-temperature heating section 161 in the flow direction of the exhaust gas G. The medium-temperature heating section 162 has a plurality of second heat transfer pipes 174. The second heat transfer pipes 174 are arranged in the exhaust gas passage 121e along the flow direction of the exhaust gas G. An end 174a of the second heat transfer pipe 174 located downstream in the flow direction of the exhaust gas G is connected to the first header 175, and an end 174b located upstream in the flow direction of the exhaust gas G is connected to the second header 176.

[0032] The low-temperature heating section 163 is arranged upstream of the medium-temperature heating section 162 in the flow direction of the exhaust gas G. The low-temperature heating section 163 has a plurality of third heat transfer pipes 177. The third heat transfer pipes 177 are arranged in the exhaust gas passage 121e along the flow direction of the exhaust gas G. An end 177a of the third heat transfer pipe 177 located downstream in the flow direction of the exhaust gas G is connected to the first header 178, and an end 177b located upstream in the flow direction of the exhaust gas G is connected to the second header 179.

[0033] The first heat medium circulation line L11 has an upstream end connected to the second header 179 of the low-temperature heating section 163 in the reheating device 105, and a downstream end connected to the second header 159 of the low-temperature heat recovery section 143 in the heat recovery device 101. In addition, the second heat medium circulation line L12 has an upstream end connected to the first header 152 of the high-temperature heat recovery section 141 in the heat recovery device 101, and a downstream end connected to the first header 172 of the high-temperature heating section 161.

[0034] The second header 153 of the high-temperature heat recovery section 141 and the first header 155 of the medium-temperature heat recovery section 142 are connected via a first connection line L21. The second header 156 of the medium-temperature heat recovery section 142 and the first header 158 of the low-temperature heat recovery section 143 are connected via a second connection line L22. Furthermore, the second header 173 of the high-temperature heating section 161 and the first header 65 of the medium-temperature heating section 162 are connected via a first connection line L23. The second header 156 of the medium-temperature heating section 162 and the first header 178 of the low-temperature heating section 163 are connected via a second connection line L24.

[0035] The first heat medium circulation line L11 is provided with a circulation pump 131 and a drain tank 133, and the second heat medium circulation line L12 is provided with a heater 132. A steam line L13 is provided from a steam supply source (not shown) to the heater 132 and the drain tank 133, and a steam drain line L14 is provided to the drain tank 133. An on-off valve 134 is provided on the steam line L13.

[0036] Therefore, the reheated low-temperature heat medium is supplied to the heat recovery unit 101 from the first heat medium circulation line L11. In the heat recovery unit 101, the heat medium flows through the low-temperature heat recovery unit 143, the medium-temperature heat recovery unit 142, and the high-temperature heat recovery unit 141 in this order, and recovers heat from the exhaust gas G as it flows through the heat transfer tubes 151, 154, and 157. The heat medium from which the heat of the exhaust gas G has been recovered is discharged to the second heat medium circulation line L12. The high-temperature heat medium from which the heat has been recovered is supplied to the reheating unit 105 from the second heat medium circulation line L12. In the reheating unit 105, the heat medium flows through the high-temperature heating unit 161, the medium-temperature heating unit 162, and the low-temperature heating unit 163 in this order, and reheats the exhaust gas G as it flows through the heat transfer tubes 171, 174, and 177. The heat medium that has reheated the exhaust gas G is discharged to the first heat medium circulation line L11.

[0037] [Heat exchanger configuration] In this embodiment, the heat exchanger is described as being applied to the reheating device 105 (high-temperature heating section 161, medium-temperature heating section 162, low-temperature heating section 163) in the above-mentioned flue gas treatment device 100. However, the heat exchanger is not limited to the reheating device 105 in the flue gas treatment device 100. The heat exchanger may also be applied to the heat recovery device 101 in the flue gas treatment device 100 or a heat exchanger other than that in the flue gas treatment device 100.

[0038] Fig. 3 is a schematic plan view showing the heat exchanger of this embodiment, and Fig. 4 is a schematic side view showing the heat exchanger of this embodiment. The heat exchanger of this embodiment is of a horizontal type in which exhaust gas G flows horizontally and heat transfer tubes are arranged along a horizontal direction that intersects with the flow direction of the exhaust gas G. However, the heat exchanger is not limited to this type, and may be, for example, of a vertical type in which exhaust gas G flows horizontally and heat transfer tubes are arranged along a vertical direction that intersects with the flow direction of the exhaust gas G. Alternatively, the heat exchanger may be configured so that exhaust gas G flows along the vertical direction.

[0039] 3 and 4, the heat exchanger 11 (reheating device 105) includes one bundle 12. However, the heat exchanger 11 may include multiple bundles 12. That is, the bundle 12 corresponds to, for example, the high-temperature heating section 161, the medium-temperature heating section 162, and the low-temperature heating section 163 (all of which are shown in FIG. 1) that constitute the reheating device 105.

[0040] The bundle 12 is disposed inside a duct casing 13. The duct casing 13 has a rectangular cylindrical shape that is aligned in the horizontal direction, and an exhaust gas passage (gas path) 14 is defined inside the duct casing 13. The exhaust gas passage 14 is provided in the horizontal direction, and the exhaust gas G flows along the horizontal direction. The bundle 12 has a casing 21, an inlet header 22, an outlet header 23, and a plurality of heat transfer tubes 24. The bundle 12 is disposed inside the duct casing 13 and is supported by the inner wall portion of the duct casing 13.

[0041] The inlet header 22 and the outlet header 23 are fixed to and supported by the side wall portion 13a of the duct casing 13. The inlet header 22 and the outlet header 23 have a cylindrical tubular shape and are closed at each longitudinal end. The inlet header 22 and the outlet header 23 are arranged vertically and spaced apart horizontally. The inlet header 22 and the outlet header 23 are arranged in openings formed in the side wall portion 13a of the duct casing 13 and are fixed to and supported. One horizontal side of the inlet header 22 and the outlet header 23 faces the exhaust gas passage 14 defined in the duct casing 13, and the other horizontal side faces the outside of the duct casing 13 (exhaust gas passage 14).

[0042] The heat transfer tubes 24 are arranged partially horizontally. The heat transfer tubes 24 are arranged horizontally intersecting the longitudinal directions of the inlet header 22 and the outlet header 23. One longitudinal end of each of the heat transfer tubes 24 is connected to the inlet header 22, and the other longitudinal end of each of the heat transfer tubes 24 is connected to the outlet header 23. The heat transfer tubes 24 are located in the exhaust gas passage 14. That is, one end of each of the heat transfer tubes 24 is connected to the side of the inlet header 22 that faces the exhaust gas passage 14, and the interior of each of the heat transfer tubes 24 communicates with the interior of the inlet header 22. The other end of each of the heat transfer tubes 24 is connected to the side of the outlet header 23 that faces the exhaust gas passage 14, and the interior of each of the heat transfer tubes 24 communicates with the interior of the outlet header 23.

[0043] A casing 21 is disposed on the outside of the bundle 12. The casing 21 is disposed so as to surround the plurality of heat transfer tubes 24, and its longitudinal ends are connected to the inlet header 22 and the outlet header 23, and is supported on the inner wall of the duct casing 13. The casing 21 has openings on the upstream and downstream sides in the flow direction (horizontal direction) of the exhaust gas G.

[0044] A flange joint 32 having a connecting flange 31 on its side is fixed to the inlet header 22. The flange joint 32 is cylindrical and is connected to the side of the inlet header 22 that does not face the exhaust gas passage 14, with its interior communicating with the interior of the inlet header 22. The flange joint 32 is arranged at one end of the inlet header 22 in the longitudinal direction. A flange joint 34 having a connecting flange 33 on its side is fixed to the outlet header 23. The flange joint 34 is cylindrical and is connected to the side of the outlet header 23 that does not face the exhaust gas passage 14, with its interior communicating with the interior of the outlet header 23. The flange joint 34 is arranged at the other end of the outlet header 23 in the longitudinal direction.

[0045] The heat transfer tubes 24 have a plurality of straight portions 24a, a plurality of first curved portions 24b, and a plurality of second curved portions 24c. The plurality of straight portions 24a are formed by a base tube with spiral fins fixed around the periphery thereof. The plurality of first curved portions 24b and the plurality of second curved portions 24c are formed only by base tubes and are not provided with fins. Adjacent straight portions 24a are connected at one end by a first curved portion 24b, and adjacent straight portions 24a are connected at the other end by a second curved portion 24c. One end of the straight portion 24a of the heat transfer tube 24 located downstream in the flow direction of the exhaust gas G is connected to the inlet header 22, and one end of the straight portion 24a located upstream in the flow direction of the exhaust gas G is connected to the outlet header 23.

[0046] In one heat transfer tube 24, the straight portion 24a, the first curved portion 24b, and the second curved portion 24c are arranged at intervals in the horizontal direction, which is the flow direction of the exhaust gas G. A plurality of heat transfer tubes 24 form a heat transfer tube group by being arranged at intervals in the vertical direction perpendicular to the flow direction of the exhaust gas G. That is, one ends of the plurality of heat transfer tubes 24 are connected to the inlet header 22 at intervals in the longitudinal direction (vertical direction), and the other ends are connected to the outlet header 23 at intervals in the longitudinal direction (vertical direction).

[0047] The heat medium supply line L31 is made of piping and has a flange joint at its end. The flange joint of the piping of the heat medium supply line L31 is connected to a flange joint 32 of the inlet header 22 of the bundle 12. The heat medium discharge line L32 is made of piping and has a flange joint at its end. The flange joint of the piping of the heat medium discharge line L32 is connected to a flange joint 34 of the outlet header 23 of the bundle 12.

[0048] A plurality of support plates 41 are arranged inside the casing 21. The plurality of support plates 41 are arranged at intervals in the longitudinal direction (horizontal direction) of the casing 21 and fixed to the casing 21. A plurality of support holes are formed in the support plate 41, and the heat transfer tubes 24 are supported by inserting their straight portions 24a into the support holes. Furthermore, a resonance prevention plate 42 is arranged inside the casing 21. The resonance prevention plate 42 is arranged along the horizontal direction, is located between the plurality of heat transfer tubes 24, and is fixed around its periphery to the casing 21. The resonance prevention plate 42 divides the interior of the casing 21, in which the plurality of heat transfer tubes 24 are arranged, into two space sections. The resonance prevention plate 42 suppresses resonance of sound generated by the vibration of the plurality of heat transfer tubes 24.

[0049] [Heat exchanger operation] The heat exchanger 11 exchanges heat between the exhaust gas G and the heat medium, thereby heating the exhaust gas G with the heat of the heat medium.

[0050] That is, the heat medium is supplied to the bundle 12 from the heat medium supply line L31, and flows from the inlet header 22 to the multiple heat transfer tubes 24. When the heat medium flows through the multiple heat transfer tubes 24, the bundle 12 exchanges heat between the heat medium and the exhaust gas G flowing through the exhaust gas passage 14. That is, the heat medium flowing through the heat transfer tubes 24 heats the exhaust gas G flowing through the exhaust gas passage 14 outside the heat transfer tubes 24. The heat medium that has exchanged heat with the exhaust gas G flows from the multiple heat transfer tubes 24 to the outlet header 23 and is discharged to the heat medium discharge line L32.

[0051] [bundle] 4, the bundle 12 includes a casing 21, an inlet header 22, an outlet header 23, and a plurality of heat transfer tubes 24. The inlet header 22 and the outlet header 23 are arranged vertically, and the plurality of heat transfer tubes 24 are arranged horizontally, with one end connected to the inlet header 22 and the other end connected to the outlet header 23.

[0052] In the bundle 12, each end of a plurality of heat transfer tubes 24 arranged in a horizontal direction is connected to an inlet header 22 and an outlet header 23 arranged in a vertical direction. In this case, the plurality of heat transfer tubes 24 are arranged at intervals in the vertical direction, which is the longitudinal direction of the inlet header 22 and the outlet header 23. In the bundle 12, of the connection portions 24d, 24e of the plurality of heat transfer tubes 24 connected to the inlet header 22 and the outlet header 23, at least the connection portions 24e of the heat transfer tubes 24 connected to the ends (uppermost end and lowermost end) of the inlet header 22 and the outlet header 23 in the longitudinal direction are connected shifted toward the connection portion 24d of the adjacent heat transfer tube 24.

[0053] That is, at least the connecting portions 24e of the heat transfer tubes 24 connected to the longitudinal ends of the inlet header 22 and the outlet header 23 are bent connecting portions. Hereinafter, the connecting portions 24e having a bent shape will be referred to as bent connecting portions 24e.

[0054] The following provides a detailed description of the bent connecting portion 24e of the heat transfer tube 24. Fig. 5 is a schematic side view showing the main part of the bundle of this embodiment.

[0055] 5, the heat transfer tubes 24 have straight portions 24a with spiral fins on the outer periphery, and are arranged at equal intervals with gaps in the longitudinal direction (vertical direction) of the inlet header 22 (outlet header 23). That is, the pitch P1 of the straight portions 24a of the heat transfer tubes 24 is the same for all of them. The pitch is the distance between the centers.

[0056] Of the plurality of heat transfer tubes 24, the plurality of heat transfer tubes 24, excluding the two upper heat transfer tubes 24 and the two lower heat transfer tubes 24, have connecting portions 24d that are linearly connected to the straight portions 24a. Hereinafter, the connecting portions 24d that are linearly connected will be referred to as straight connecting portions 24d.

[0057] Of the multiple heat transfer tubes 24, the two upper heat transfer tubes 24 and the two lower heat transfer tubes 24 have bent connecting portions 24e. In the description of Fig. 4, the connecting portion between one upper heat transfer tube 24 and one lower heat transfer tube 24 is referred to as the bent connecting portion 24e, and in the description of Fig. 5, the connecting portion between the two upper heat transfer tubes 24 and the two lower heat transfer tubes 24 is referred to as the bent connecting portion 24e, but the number of bent connecting portions 24e is not limited. It is sufficient that at least the connecting portion between the uppermost heat transfer tube 24 and the lowermost heat transfer tube 24 is the bent connecting portion 24e.

[0058] The bent connecting portion 24e includes a first straight connecting portion 24e1 that is linearly connected to the straight portion 24a of the heat transfer tube 24, a second straight connecting portion 24e2 that is parallel to the straight portion 24a and connected to the inlet header 22, and a curved connecting portion 24e3 that connects the first straight connecting portion 24e1 and the second straight connecting portion 24e2. The curved connecting portion 24e3 is S-shaped. However, the curved connecting portion 24e3 is not limited to an S-shape and may have any shape as long as it smoothly connects the ends of the first straight connecting portion 24e1 and the second straight connecting portion 24e2.

[0059] The heat transfer tubes 24 connected to the inlet header 22 by the straight connection portions 24d are arranged at equal intervals with gaps between the straight connection portions 24d in the longitudinal direction (vertical direction) of the inlet header 22. That is, the pitch P2 between the straight connection portions 24d is the same. The pitch P1 between the straight portions 24a and the pitch P2 between the straight connection portions 24d are the same. Furthermore, the heat transfer tubes 24 connected to the inlet header 22 by the bent connection portions 24e are arranged with gaps between the bent connection portions 24e in the longitudinal direction (vertical direction) of the inlet header 22. That is, the pitch P3 between the bent connection portions 24e.

[0060] On the other hand, when the straight connection portions 24d and the bent connection portions 24e of the multiple heat transfer tubes 24 are arranged adjacent to each other vertically, the pitch P4 between the straight connection portions 24d and the bent connection portions 24e is smaller than the pitches P1 and P2. Here, the pitch P3 between the bent connection portions 24e may be the same as the pitch P2 between the straight connection portions 24d, or may be smaller than the pitch P2 between the straight connection portions 24d and may be the same as or smaller than the pitch P4 between the straight connection portions 24d and the bent connection portions 24e.

[0061] In the above-described embodiment, the connecting portions of one or two heat transfer tubes 24 connected to each longitudinal end of the inlet header 22 and the outlet header 23 are defined as bent connecting portions 24e, but the number is not limited thereto. The number of bent connecting portions 24e may be set appropriately depending on the lengths of the inlet header 22 and the outlet header 23, and may be one or more. Furthermore, only the connecting portions of the heat transfer tubes 24 connected to either one longitudinal end (upper end) or the other longitudinal end (lower end) of the inlet header 22 and the outlet header 23 may be defined as bent connecting portions 24e. Furthermore, only the connecting portions of the heat transfer tubes 24 connected to the longitudinal ends of the inlet header 22 or the outlet header 23 may be defined as bent connecting portions 24e.

[0062] [Comparison of the bundle of this embodiment with the conventional bundle] 5, in the bundle 12 of this embodiment, the two heat transfer tubes 24 at the upper end and the two heat transfer tubes 24 at the lower end are connected to the inlet header 22 by bent connection portions 24e. As a result, the pitch P4 between the straight connection portions 24d and the bent connection portions 24e is smaller than the pitch P2 between the straight connection portions 24d, and the total width of the spacing between the connection portions and the inlet header 22 is reduced. As a result, the overall length L1 of the inlet header 22 to which the multiple heat transfer tubes 24 are connected can be shortened, and the overall length L2 of the bundle 12 can also be shortened. As a result, the height of the bundle 12 is reduced, allowing for a more compact size.

[0063] In this case, although the arrangement region (arrangement height) L3 of the plurality of heat transfer tubes 24 (straight portions 24a) remains unchanged, the overall length L1 of the inlet header 22 is shortened, and therefore the upper wall portion 21a and the lower wall portion 21b of the casing 21 can be arranged closer to the heat transfer tubes 24 (straight portions 24a). This makes it possible to shorten the overall height of the casing 21, i.e., the overall length L2 of the bundle 12. Note that the overall length L1 of the inlet header 22 is preferably equal to or less than the arrangement region (arrangement height) L3 of the heat transfer tubes 24 (straight portions 24a).

[0064] Furthermore, the area where the straight sections 24a of the multiple heat transfer tubes 24 are arranged is the heat exchange area, and the upper wall section 21a and the lower wall section 21b of the casing 21 can be arranged close to the heat transfer tubes 24. This reduces the amount of exhaust gas passing between the heat transfer tubes 24 and the respective wall sections of the upper wall section 21a and the lower wall section 21b of the heat transfer tubes, and allows more exhaust gas to flow in the area where the straight sections 24a are arranged, thereby increasing the heat exchange efficiency.

[0065] FIG. 6 is a schematic side view showing the main part of a conventional bundle.

[0066] 6, in the conventional bundle, all of the heat transfer tubes 24 are connected to the inlet header 22 via straight connection portions 24d, and the straight connection portions 24d are spaced apart at a pitch of P2, so the total width of the spacing between the connection portions and the inlet header 22 cannot be reduced. As a result, the total length L1 of the inlet header 22 to which multiple heat transfer tubes 24 are connected is longer than that of the bundle 12 of this embodiment, and the total length L2 of the bundle 12 is also longer. As a result, the height of the bundle increases, resulting in a larger size.

[0067] In this case, because the lowermost heat transfer tube 24 is connected to the inlet header 22 by the straight connection portion 24d, the overall length L1 of the inlet header 22 becomes long, and the lower wall portion 21b of the casing 21 must be spaced apart from the heat transfer tube 24 (straight portion 24a) by a distance S. This increases the overall height of the casing 21, i.e., the overall length L2 of the bundle. Furthermore, because the lower wall portion 21b of the casing 21 is spaced apart from the heat transfer tube 24, exhaust gas flows through this area, reducing heat exchange efficiency.

[0068] FIG. 7 is a cross-sectional view showing the upper part of the bundle of this embodiment.

[0069] As shown in Figure 7, the inlet header 22 is configured by fixing a disk member 52 to the longitudinal end of a cylindrical pipe 51. The cylindrical pipe 51 has a tapered portion 51a formed around the entire inner periphery of the end, and a fitted portion 51b formed thereon. The tapered portion 51a has an inner diameter that increases toward the end, and the fitted portion 51b has a constant inner diameter in the axial direction. On the other hand, the disk member 52 has a tapered portion 52a formed around the entire outer periphery, and a fitting portion 52b formed thereon. The inner diameter of the tapered portion 52a decreases toward the fitting portion 52b, and the fitting portion 52b has a constant outer diameter in the axial direction.

[0070] The fitting portion 52b of the disk member 52 fits into the fitted portion 51b of the cylindrical pipe 51. The cylindrical pipe 51 and the disk member 52 are joined by providing a groove weld portion 53 between the tapered portion 52a of the disk member 52 and the end face 51c of the cylindrical pipe 51 by groove welding.

[0071] In the bundle 12 of this embodiment, the bent connecting portions 24e of the heat transfer tubes 24 are connected to the ends of the inlet header 22. That is, the inlet header 22 has connecting holes 51d and work holes 51e formed at the ends of the cylindrical tubes 51. The ends of the bent connecting portions 24e of the heat transfer tubes 24 are inserted into the connecting holes 51d of the inlet header 22 and fixed therein. A plug (not shown) is also fitted into the work hole 51e. In this case, because the heat transfer tubes 24 are connected to the inlet header 22 by the bent connecting portions 24e, the connecting holes 51d and the work hole 51e should be located as far away as possible from the tapered portions 51a of the cylindrical tubes 51 to minimize the effects of seal welding.

[0072] On the other hand, in a conventional bundle, the straight connection portion 24d of the heat transfer tube 24 is connected to the end of the inlet header 22. In this case, because the straight connection portion 24d is not bent, the connection position of the straight connection portion 24d to the inlet header 22 is closer to the end (disk member 52) than the connection position of the bent connection portion 24e. In other words, the inlet header 22 needs to have the connection hole 51d and the work hole 51e on the disk member 52 side of the cylindrical tube 51. In this case, the connection hole 51d and the work hole 51e are close to the tapered portion 51a of the cylindrical tube 51. If the connection hole 51d is close to the tapered portion 51a, it becomes difficult to seal weld the straight connection portion 24d when it is inserted into the connection hole 51d and fixed. Furthermore, if the work hole 51e interferes with the tapered portion 51a, heat is more likely to be transferred to the work hole 51e when groove welding the disk member 52 to the cylindrical pipe 51, which may result in deformation of the work hole 51e. As a result, the end of the inlet header 22 must be extended upward, which increases the overall length of the inlet header 22.

[0073] [Effects of this embodiment] The bundle according to the first embodiment comprises an inlet header 22 to which a heat transfer medium is supplied, an outlet header 23 from which the heat transfer medium is discharged, and a plurality of heat transfer tubes 24 connecting the inlet header 22 and the outlet header 23, and among the connection portions of the plurality of heat transfer tubes 24 connected to the inlet header 22 and the outlet header 23, at least the connection portion 24e of the heat transfer tube 24 connected to the longitudinal end portion side of the inlet header 22 and the outlet header 23 is shifted toward the connection portion 24d of the adjacent heat transfer tube 24 and connected to the inlet header 22 and the outlet header 23.

[0074] According to the bundle of the first aspect, the connecting portions 24e of the heat transfer tubes 24 connected to the longitudinal ends of the inlet header 22 and the outlet header 23 are shifted toward the connecting portion 24d of the adjacent heat transfer tube 24, thereby shortening the overall length of the inlet header 22 and the outlet header 23. As a result, the bundle 12 can be made smaller and heat exchange performance can be improved.

[0075] The bundle according to the second embodiment is the bundle according to the first embodiment, and further includes a bent connecting portion 24e as the connecting portion of the heat transfer tubes 24 connected to at least the longitudinal ends of the inlet header 22 and the outlet header 23. This allows the heat transfer tubes 24 to be appropriately connected at offset positions relative to the inlet header 22 and the outlet header 23 by the bent connecting portion 24e.

[0076] The bundle according to the third embodiment is the bundle according to the second embodiment, further comprising: a first straight connection portion 24e1 linearly continuing from the straight portion 24a of the heat transfer tube 24; a second straight connection portion 24e2 parallel to the straight portion 24a and connected to the inlet header 22 or the outlet header 23; and a curved connection portion 24e3 connecting the first straight connection portion 24e1 and the second straight connection portion 24e2. This allows the heat transfer tube 24 to be smoothly connected to the inlet header 22 or the outlet header 23 by the curved connection portion 24e.

[0077] The bundle according to the fourth aspect is the bundle according to the third aspect, further including curved connecting portion 24e3 having an S-shape, thereby enabling first straight connecting portion 24e1 and second straight connecting portion 24e2 to be smoothly connected by curved connecting portion 24e3.

[0078] A bundle according to a fifth aspect is the bundle according to any one of the second to fourth aspects, wherein the finned straight portions 24a of the plurality of heat transfer tubes 24 are equally spaced apart with gaps in the longitudinal direction of the inlet header 22 and the outlet header 23, and among the connection portions of the plurality of heat transfer tubes 24 connected to the inlet header 22 and the outlet header 23, the connection portions of the heat transfer tubes 24 connected to the longitudinally intermediate portions of the inlet header 22 and the outlet header 23 are straight connection portions 24d that linearly continue from the straight portions, and the distance between the bent connection portions 24e and the straight connection portions 24d is shorter than the distance between the straight connection portions 24d themselves. This allows the overall length of the inlet header 22 and the outlet header 23 to be shortened.

[0079] The heat exchanger according to the sixth aspect includes a duct casing 13 that forms an exhaust gas passage 14, and a bundle 12 that is disposed inside the duct casing 13. This allows the bundle 12 to be made smaller, and also allows the heat exchange performance to be improved.

[0080] The flue gas treatment device according to the seventh aspect includes a heat recovery device 101 that recovers a portion of the heat of the flue gas G, an electrostatic precipitator 102 that removes soot and dust contained in the flue gas G after the heat recovery, a desulfurization device 104 that removes sulfur oxides contained in the flue gas G after the dust collection, and a reheating device 105 that employs a heat exchanger 11 that reheats the desulfurized flue gas G. This allows the bundle 12 to be made smaller and the heat exchange performance to be improved. [Explanation of symbols]

[0081] 11 Heat exchanger 12 bundles 13 Duct casing 14 Exhaust gas passage 21 Casing 22 Inlet Header 23 Exit Header 24 Heat transfer tube 24a Straight section 24b First curved section 24c Second curved section 24d Straight connection 24e Bend connection 31,33 Connecting flange 32,34 Flange joint 41 Support plate 42 Resonance prevention plate 100 Smoke treatment equipment 101 Heat recovery device 102 Electrostatic Precipitator 103 Blower 104 Desulfurization equipment 105 Reheating device 106 Blower 111 Boiler 112 Chimney 121a, 121b, 121c, 121d, 121e, 121f, 121g, 121h, 121i 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, L23 First connection line L22, L24 Second connection line L31 Heat medium supply line L32 Heat transfer medium discharge line G. Exhaust gas

Claims

1. an inlet header to which the heat transfer medium is supplied; an outlet header through which the heat transfer medium is discharged; a plurality of heat transfer tubes connecting the inlet header and the outlet header; a casing disposed to surround the plurality of heat transfer tubes, the casing having longitudinal ends connected to the inlet header and the outlet header; Equipped with Among the connection portions of the heat transfer tubes connected to the inlet header and the outlet header, at least the connection portions of the heat transfer tubes connected to the end portions of the inlet header and the outlet header in the longitudinal direction adjacent to the wall portion of the casing are connected to the inlet header and the outlet header while being shifted toward the connection portions of the adjacent heat transfer tubes. bundle.

2. At least the connection portions of the heat transfer tubes connected to the ends of the inlet header and the outlet header in the longitudinal direction are bent connection portions. The bundle of claim 1 .

3. The bent connecting portion includes a first straight connecting portion linearly continuing to the straight portion of the heat transfer tube, a second straight connecting portion parallel to the straight portion and connected to the inlet header or the outlet header, and a curved connecting portion connecting the first straight connecting portion and the second straight connecting portion. The bundle of claim 2 .

4. The curved connecting portion has an S-shape. The bundle of claim 3 .

5. The plurality of heat transfer tubes have finned straight portions arranged at equal intervals with gaps in the longitudinal direction of the inlet header and the outlet header, Among the connection portions of the heat transfer tubes connected to the inlet header and the outlet header, the connection portions of the heat transfer tubes connected to the inlet header and the outlet header at intermediate portions in the longitudinal direction are straight connection portions that are linearly continued from straight portions, and a distance between the bent connection portion and the straight connection portion is shorter than a distance between the straight connection portions. The bundle of claim 2 .

6. The inlet header and the outlet header are closed at their respective longitudinal ends and are arranged side by side, The heat transfer tube has at least two straight sections arranged adjacent to each other and a curved section connecting one end of the two straight sections in the longitudinal direction, and the other end of one of the two straight sections in the longitudinal direction is connected to the inlet header, and the other end of the other of the two straight sections in the longitudinal direction is connected to the outlet header. The bundle of claim 1 .

7. a duct casing that forms an exhaust gas passage; The bundle of claim 1 disposed inside the duct casing; A heat exchanger comprising:

8. a heat recovery device that recovers a portion of the heat of the exhaust gas; a dust collector that removes soot and 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 reheating device to which the heat exchanger according to claim 7 is applied, which reheats the exhaust gas after desulfurization; A smoke treatment device comprising:

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