Bundles and heat exchangers and flue gas treatment equipment

Abstract

The goal is to miniaturize the bundles, heat exchangers, and flue gas treatment systems. [Solution] The system comprises an inlet header to which a heat transfer medium is supplied, an outlet header to which the heat transfer medium is discharged, and a plurality of heat transfer tubes connected to the inlet header and the outlet header. At least the connection points of the heat transfer tubes connected to the longitudinal end of the inlet header and the outlet header are offset from the connection points 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 Art

[0002] A flue gas treatment device provided in a thermal power generation facility or the like includes a heat recovery device, an electrostatic precipitator, a desulfurization device, a reheating device, and the like. The flue gas discharged from the boiler is subjected to removal of dust contained therein by an electrostatic precipitator and removal of sulfurous acid gas contained therein by a desulfurization device. At this time, the heat recovery device recovers heat from the flue gas. The reheating device reheats the flue gas after desulfurization by the heat recovered by the heat recovery device to suppress the discharge of white smoke.

[0003] A heat exchanger as a heat recovery device or a reheating device includes an inlet header, an outlet header, and a plurality of heat transfer tubes. One ends of the plurality of heat transfer tubes are connected to the inlet header, and the other ends are connected to the outlet header. When the heat medium supplied to the inlet header flows through the plurality of heat transfer tubes and is discharged to the outlet header, it exchanges heat with the flue gas flowing through the flue gas passage. As such a heat exchanger, for example, there is one described in Patent Document 1.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The inlet header and the outlet header are arranged along the vertical direction or the horizontal direction, and the ends of the plurality of heat transfer tubes are respectively connected thereto. The plurality of heat transfer tubes are arranged at equal intervals with a gap in the longitudinal direction of the inlet header and the outlet header. Therefore, there is a problem that the inlet header and the outlet header require a length equal to or greater than the array length of the plurality of heat transfer tubes, resulting in an increase in size.

[0006] This disclosure aims to solve the aforementioned problems and to provide bundles, heat exchangers, and flue gas treatment devices that enable miniaturization of the device and improvement of heat exchange performance. [Means for solving the problem]

[0007] To achieve the above objective, the bundle of the present disclosure 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 connecting the inlet header and the outlet header, wherein at least the connection portion of the heat transfer tubes connected to the longitudinal end of the inlet header and the outlet header is offset towards the connection portion of the adjacent heat transfer tube.

[0008] Furthermore, the heat exchanger of this disclosure comprises a duct casing that forms an exhaust gas passage, and the bundle disposed inside the duct casing.

[0009] Furthermore, the flue gas treatment device of this disclosure includes a heat recovery device for recovering a portion of the heat from the exhaust gas, a dust collector for removing soot contained in the exhaust gas after heat recovery, a desulfurization device for removing sulfur oxides contained in the exhaust gas after dust collection, and a reheating device to which the heat exchanger is applied for reheating the exhaust gas after desulfurization. [Effects of the Invention]

[0010] The heat transfer tubes, heat exchangers, and flue gas treatment devices of this disclosure can be miniaturized and their heat exchange performance improved. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a schematic diagram showing the flue gas treatment apparatus of this embodiment. [Figure 2] Figure 2 is a schematic diagram showing the heat recovery device and reheating device of this embodiment. [Figure 3]Figure 3 is a schematic plan view of the heat exchanger of this embodiment. [Figure 4] Figure 4 is a schematic side view of the heat exchanger of this embodiment. [Figure 5] Figure 5 is a schematic side view showing the main parts of the bundle in this embodiment. [Figure 6] Figure 6 is a schematic side view showing the main components of a conventional bundle. [Figure 7] Figure 7 is a cross-sectional view showing the top of the bundle in this embodiment. [Modes for carrying out the invention]

[0012] Preferred embodiments of the present disclosure will be described in detail below with reference to the drawings. However, these embodiments do not limit the present disclosure, and where there are multiple embodiments, they may be combinations of these embodiments. Furthermore, the components in the embodiments include those readily conceivable by those skilled in the art, those that are substantially identical, and those that are equivalent.

[0013] [Smoke exhaust treatment system] Figure 1 is a schematic diagram showing the flue gas treatment apparatus of this embodiment.

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

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

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

[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 device 103a, and the exhaust gas passage 121b is provided with a heat recovery device 101b, an electrostatic precipitator 102b, and a blower device 103b. The downstream sides of the two exhaust gas passages 121a and 121b merge into an exhaust gas passage 121c. The exhaust gas passage 121c branches into two exhaust gas passages 121d and 121e. The exhaust gas passage 121d forms a part of the first treatment system, and a shut-off valve 122 is provided in the middle, and the downstream side is connected to the chimney 112.

[0018] The exhaust gas passage 121e constitutes the second treatment system, and the desulfurization device 104 and the reheating device 105 are provided. The downstream side of the exhaust gas passage 121e branches into two exhaust gas passages 121f and 121g. The air blower 106a is provided in the exhaust gas passage 121f, and the air blower 106b is provided in the exhaust gas passage 121g. The downstream sides of the two exhaust gas passages 121f and 121g merge into the exhaust gas passage 121h. Then, the exhaust gas passage 121d that constitutes a part of the first treatment system and the exhaust gas passage 121h that constitutes a part of the second treatment system merge into the 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 (about 140 °C) by exchanging heat between the exhaust gas G discharged from the boiler 111 and a heat medium (such as water). The exhaust gas G (about 90 °C) from which heat has been recovered by the heat recovery device 101 is introduced into the electric dust collector 102(102a, 102b). The electric dust collector 102 removes dust from the exhaust gas G.

[0020] The exhaust gas G from which dust has been removed by the electric dust collector 102 is introduced into the desulfurization device 104. The desulfurization device 104 absorbs and removes sulfur oxides in the exhaust gas G with limestone (CaCO3) and generates gypsum (CaSO4·2H2O) 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.

[0021] The exhaust gas G (approximately 50°C) desulfurized by the desulfurization unit 104 is introduced into the gas heater reheating unit 105. The reheating unit 105 reheats the exhaust gas G with the heat recovered by the heat recovery unit 101 during the process of circulating the heat transfer medium between it and the heat recovery unit 101. The heat recovery unit 101 and the reheating unit 105 are connected by a first heat transfer medium circulation line L11 and a second heat transfer medium circulation line L12. The first heat transfer medium circulation line L11 is equipped with a circulation pump 131. When the circulation pump 131 is driven, the heat transfer medium from the reheating unit 105 is returned to the heat recovery unit 101 via the first heat transfer medium circulation line L11. The second heat transfer medium circulation line L12 is equipped with a heater 132. The circulation pump 131 supplies the heat transfer medium from the heat recovery unit 101 to the reheating unit 105 via the second heat transfer medium circulation line L12. During this process, the heat transfer medium is heated by activating the heater 132 as needed.

[0022] The exhaust gas G is desulfurized in the desulfurization unit 104, which lowers its temperature. At low temperatures, it may not diffuse easily and could turn into white smoke. The reheating unit 105 reheats the exhaust gas G to raise its temperature (to approximately 90°C) for the purpose of diffusion and reduction of white smoke, and then releases it into the atmosphere through the chimney 112. The temperature of the exhaust gas G mentioned above is just an example and is not limited to this.

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

[0024] As shown in Figure 2, the heat recovery device 101 and the reheating device 105 are heat exchangers of the fully counterflow type. However, the heat recovery device 101 and the reheating device 105 may be heat exchangers of other types, such as high-temperature preheating counterflow type, high-temperature preheating parallel flow type, or medium-temperature preheating type.

[0025] The heat recovery device 101 comprises a high-temperature heat recovery unit 141, a medium-temperature heat recovery unit 142, and a low-temperature heat recovery unit 143. The high-temperature heat recovery unit 141, the medium-temperature heat recovery unit 142, and the low-temperature heat recovery unit 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 consist of one heat recovery unit or multiple heat recovery units.

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

[0027] The intermediate-temperature heat recovery unit 142 is located downstream of the high-temperature heat recovery unit 141 in the flow direction of the exhaust gas G. The intermediate-temperature heat recovery unit 142 has a plurality of second heat transfer tubes 154. The second heat transfer tubes 154 are arranged in the exhaust gas passage 121a (121b) along the flow direction of the exhaust gas G. The ends 154a of the second heat transfer tubes 154 located upstream in the flow direction of the exhaust gas G are connected to the first header 155, and the ends 154b located downstream in the flow direction of the exhaust gas G are connected to the second header 156.

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

[0029] The reheating device 105 comprises 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 consist of one heating section or multiple heating sections.

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

[0031] The medium-temperature heating section 162 is located 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 tubes 174. The second heat transfer tubes 174 are arranged in the exhaust gas passage 121e along the flow direction of the exhaust gas G. The ends 174a of the second heat transfer tubes 174 located downstream in the flow direction of the exhaust gas G are connected to the first header 175, and the ends 174b located upstream in the flow direction of the exhaust gas G are connected to the second header 176.

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

[0033] The first heat transfer medium circulation line L11 has its upstream end connected to the second header 179 of the low-temperature heating section 163 in the reheating device 105, and its downstream end connected to the second header 159 of the low-temperature heat recovery section 143 in the heat recovery device 101. The second heat transfer medium circulation line L12 has its upstream end connected to the first header 152 of the high-temperature heat recovery section 141 in the heat recovery device 101, and its 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 unit 141 and the first header 155 of the medium-temperature heat recovery unit 142 are connected via the first connection line L21. The second header 156 of the medium-temperature heat recovery unit 142 and the first header 158 of the low-temperature heat recovery unit 143 are connected via the second connection line L22. In addition, the second header 173 of the high-temperature heating unit 161 and the first header 65 of the medium-temperature heating unit 162 are connected via the first connection line L23. The second header 156 of the medium-temperature heating unit 162 and the first header 178 of the low-temperature heating unit 163 are connected via the second connection line L24.

[0035] Furthermore, the first heat transfer medium circulation line L11 is equipped with a circulation pump 131 and a drain tank 133, and the second heat transfer medium circulation line L12 is equipped 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. A shut-off valve 134 is provided for the steam line L13.

[0036] Therefore, the reheated low-temperature heat transfer medium is supplied from the first heat transfer medium circulation line L11 to the heat recovery device 101. In the heat recovery device 101, the heat transfer medium flows in the order of low-temperature heat recovery section 143, medium-temperature heat recovery section 142, and high-temperature heat recovery section 141, recovering heat from the exhaust gas G as it flows through each heat transfer tube 151, 154, and 157. The heat transfer medium from which heat has been recovered from the exhaust gas G is discharged to the second heat transfer medium circulation line L12. The high-temperature heat transfer medium from which heat has been recovered is supplied from the second heat transfer medium circulation line L12 to the reheating device 105. In the reheating device 105, the heat transfer medium flows in the order of high-temperature heating section 161, medium-temperature heating section 162, and low-temperature heating section 163, reheating the exhaust gas G as it flows through each heat transfer tube 171, 174, and 177. The heat transfer medium from which the exhaust gas G has been reheated is discharged to the first heat transfer 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 flue gas treatment device 100 described above. 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 to a heat exchanger other than the flue gas treatment device 100.

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

[0039] As shown in Figures 3 and 4, the heat exchanger 11 (reheating device 105) comprises one bundle 12. However, the heat exchanger 11 may comprise multiple bundles 12. That is, the bundles 12 correspond 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 Figure 1) that constitute the reheating device 105.

[0040] The bundle 12 is positioned inside the duct casing 13. The duct casing 13 has a rectangular cylindrical shape aligned horizontally, and an exhaust gas passage (gas path) 14 is partitioned inside. The exhaust gas passage 14 is provided along 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 positioned inside the duct casing 13 and is supported by the inner wall of the duct casing 13.

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

[0042] Multiple heat transfer tubes 24 are arranged in a manner that partially follows a horizontal direction. Multiple heat transfer tubes 24 are arranged in a horizontal direction that intersects the longitudinal directions of the inlet header 22 and the outlet header 23. The inlet header 22 is connected to one longitudinal end of the multiple heat transfer tubes 24, and the outlet header 23 is connected to the other longitudinal end of the multiple heat transfer tubes 24. Multiple heat transfer tubes 24 are located in the exhaust gas passage 14. That is, one end of the multiple heat transfer tubes 24 is connected to the side of the inlet header 22 facing the exhaust gas passage 14, and the interior of the tubes communicates with the interior of the inlet header 22. The other end of the multiple heat transfer tubes 24 is connected to the side of the outlet header 23 facing the exhaust gas passage 14, and the interior of the tubes communicates with the interior of the outlet header 23.

[0043] The bundle 12 has a casing 21 positioned on the outside. The casing 21 is positioned to surround the multiple heat transfer tubes 24, and its longitudinal ends are connected to the inlet header 22 and outlet header 23, and it is supported by 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] The inlet header 22 is fixed to a flange joint 32 having a connecting flange 31 on its side. The flange joint 32 is cylindrical in shape 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 located at one end of the inlet header 22 in the longitudinal direction. The outlet header 23 is fixed to a flange joint 34 having a connecting flange 33 on its side. The flange joint 34 is cylindrical in shape 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 located at the other end of the outlet header 23 in the longitudinal direction.

[0045] The heat transfer tube 24 has a plurality of straight sections 24a, a plurality of first curved sections 24b, and a plurality of second curved sections 24c. The plurality of straight sections 24a are constructed by fixing spiral-shaped fins around the periphery of the pipe. The plurality of first curved sections 24b and the plurality of second curved sections 24c are constructed only of pipe and do not have fins. The plurality of straight sections 24a are connected at one end of adjacent sections by the first curved section 24b, and at the other end of adjacent sections by the second curved section 24c. The heat transfer tube 24 has one end of the straight section 24a on the downstream side in the direction of exhaust gas G flow connected to the inlet header 22, and one end of the straight section 24a on the upstream side in the direction of exhaust gas G flow connected to the outlet header 23.

[0046] Each heat transfer tube 24 has a straight section 24a, a first curved section 24b, and a second curved section 24c, which are spaced apart in the horizontal direction, which is the flow direction of the exhaust gas G. Multiple heat transfer tubes 24 are spaced apart in the vertical direction, which is perpendicular to the flow direction of the exhaust gas G, thereby forming a heat transfer tube group. That is, one end of each of the multiple heat transfer tubes 24 is connected at a distance in the longitudinal direction (vertical direction) of the inlet header 22, and the other end is connected at a distance in the longitudinal direction (vertical direction) of the outlet header 23.

[0047] The heat transfer medium supply line L31 is made up of piping and has flanged joints at its ends. The flanged joints of the piping in the heat transfer medium supply line L31 are connected to the flanged joints 32 of the inlet header 22 in the bundle 12. The heat transfer medium discharge line L32 is made up of piping and has flanged joints at its ends. The flanged joints of the piping in the heat transfer medium discharge line L32 are connected to the flanged joints 34 of the outlet header 23 in the bundle 12.

[0048] The casing 21 has multiple support plates 41 arranged inside. The multiple support plates 41 are arranged at intervals along the longitudinal direction (horizontal direction) of the casing 21 and are fixed to the casing 21. Multiple support holes are formed in the support plates 41, and the heat transfer tubes 24 are supported by inserting the straight sections 24a into the support holes. The casing 21 also has a resonance prevention plate 42 arranged inside. The resonance prevention plate 42 is arranged along the horizontal direction, positioned between the multiple heat transfer tubes 24, and its periphery is fixed to the casing 21. The resonance prevention plate 42 divides the inside of the casing 21, where the multiple heat transfer tubes 24 are arranged, into two spaces. The resonance prevention plate 42 suppresses sound resonance generated by the vibration of the multiple heat transfer tubes 24.

[0049] [Heat exchanger operation] The heat exchanger 11 heats the exhaust gas G by exchanging heat between the exhaust gas G and the heat transfer medium, thereby heating the exhaust gas G with the heat from the heat transfer medium.

[0050] In other words, the heat transfer medium is supplied from the heat transfer medium supply line L31 to the bundle 12 and flows from the inlet header 22 to the multiple heat transfer tubes 24. As the heat transfer medium flows through the multiple heat transfer tubes 24, the bundle 12 performs heat exchange between the heat transfer medium and the exhaust gas G flowing through the exhaust gas passage 14. That is, the heat transfer 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 transfer 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 transfer medium discharge line L32.

[0051] [bundle] As shown in Figure 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] Bundle 12 connects the ends of multiple heat transfer tubes 24, which are arranged horizontally, to the inlet header 22 and outlet header 23, which are arranged vertically. In this case, the multiple heat transfer tubes 24 are spaced apart in the vertical direction, which is the longitudinal direction of the inlet header 22 and outlet header 23. Of the connection portions 24d and 24e of the multiple heat transfer tubes 24 connected to the inlet header 22 and outlet header 23, at least the connection portion 24e of the heat transfer tube 24 connected to the outermost end (uppermost and lowermost end) in the longitudinal direction of the inlet header 22 and outlet header 23 is offset and connected to the connection portion 24d of the adjacent heat transfer tube 24.

[0053] In other words, the connecting portion 24e of the heat transfer tube 24 connected to the longitudinal end side of at least the inlet header 22 and outlet header 23 is a bent connecting portion. Hereinafter, the bent connecting portion 24e will be referred to as the bent connecting portion 24e.

[0054] The bent connection portion 24e of the heat transfer tube 24 will be described in detail below. Figure 5 is a schematic side view showing the main part of the bundle of this embodiment.

[0055] As shown in Figure 5, the multiple heat transfer tubes 24 have straight sections 24a with spiral-shaped fins on their outer circumference and are arranged at equal intervals with gaps between them in the longitudinal direction (vertical direction) of the inlet header 22 (outlet header 23). That is, the pitch P1 of each straight section 24a in the multiple heat transfer tubes 24 is the same. Note that the pitch is the distance between the centers.

[0056] Of the multiple heat transfer tubes 24, all but the two upper and two lower heat transfer tubes 24 have a linear connection section 24d where the connection section 24d is linearly continuous with respect to the straight section 24a. Hereinafter, the linearly continuous connection section 24d will be referred to as the linear connection section 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 a bent joint 24e at their connection point. In the explanation of Figure 4, the connection point between one upper heat transfer tube 24 and one lower heat transfer tube 24 is described as a bent joint 24e, and in the explanation of Figure 5, the connection points between the two upper heat transfer tubes 24 and the two lower heat transfer tubes 24 are described as bent joints 24e. However, the number of bent joints 24e is not limited. At least the connection point between the uppermost heat transfer tube 24 and the lowermost heat transfer tube 24 must be a bent joint 24e.

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

[0059] Multiple heat transfer tubes 24 connected to the inlet header 22 by linear connecting sections 24d are arranged at equal intervals with gaps between each linear connecting section 24d relative to the longitudinal direction (vertical direction) of the inlet header 22. That is, the pitch P2 between multiple linear connecting sections 24d is the same. Note that the pitch P1 between linear sections 24a and the pitch P2 between linear connecting sections 24d are the same. In addition, multiple heat transfer tubes 24 connected to the inlet header 22 by bent connecting sections 24e are arranged with gaps between each bent connecting section 24e relative to the longitudinal direction (vertical direction) of the inlet header 22. That is, the pitch P3 between multiple bent connecting sections 24e.

[0060] On the other hand, when a linear connecting section 24d and a bent connecting section 24e are arranged adjacent to each other vertically among a plurality of heat transfer tubes 24, the pitch P4 between the linear connecting section 24d and the bent connecting section 24e is smaller than the respective pitches P1 and P2. Here, the pitch P3 between the bent connecting sections 24e may be the same as the pitch P2 between the linear connecting sections 24d, but it may be smaller than the pitch P2 between the linear connecting sections 24d, and may be the same as or smaller than the pitch P4 between the linear connecting section 24d and the bent connecting section 24e.

[0061] In the above-described embodiment, the connection points of one or two heat transfer tubes 24 connected to each longitudinal end of the inlet header 22 and outlet header 23 are designated as bent connection points 24e, but the number is not limited. The number of bent connection points 24e can be set appropriately according to the length of the inlet header 22 and outlet header 23, and may be one or more. Furthermore, the connection points 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 outlet header 23 may be designated as bent connection points 24e. In addition, the connection points of the heat transfer tubes 24 connected to the longitudinal ends of either the inlet header 22 or the outlet header 23 may be designated as bent connection points 24e.

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

[0063] In this case, although the arrangement area (arrangement height) L3 of the multiple heat transfer tubes 24 (straight section 24a) remains unchanged, the total length L1 of the inlet header 22 is shortened, allowing the upper wall 21a and lower wall 21b of the casing 21 to be positioned closer to the heat transfer tubes 24 (straight section 24a). Therefore, the total height of the casing 21, i.e., the total length L2 of the bundle 12, can be shortened. It is preferable that the total length L1 of the inlet header 22 be less than or equal to the arrangement area (arrangement height) L3 of the heat transfer tubes 24 (straight section 24a).

[0064] Furthermore, since the arrangement of the straight sections 24a in the multiple heat transfer tubes 24 is the heat exchange region, and the upper wall 21a and lower wall 21b of the casing 21 can be arranged close to the heat transfer tubes 24, the amount of exhaust gas passing between the respective walls of the upper wall 21a and lower wall 21b of the heat transfer tubes and the heat transfer tubes 24 can be reduced, allowing more exhaust gas to flow into the region where the straight sections 24a are arranged, thereby increasing the heat exchange efficiency.

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

[0066] As shown in Figure 6, in a conventional bundle, all heat transfer tubes 24 have straight connection sections 24d at their connection points to the inlet header 22, and the pitch between these straight connection sections 24d is P2. Therefore, the total width of the spacing between each connection section relative to the inlet header 22 cannot be reduced. Consequently, the total length L1 of the inlet header 22 to which multiple heat transfer tubes 24 are connected becomes longer than that of the bundle 12 in this embodiment, and the total length L2 of the bundle 12 also becomes longer. As a result, the height of the bundle increases, making it larger.

[0067] In this case, since the lowest heat transfer tube 24 is connected to the inlet header 22 by a straight connecting section 24d, the total length L1 of the inlet header 22 becomes longer, and the lower wall section 21b of the casing 21 must be positioned at a distance S from the heat transfer tube 24 (straight section 24a). As a result, the total height of the casing 21, i.e., the total length L2 of the bundle, becomes longer. Also, because the lower wall section 21b of the casing 21 is separated from the heat transfer tube 24, exhaust gas flows through this area, reducing the heat exchange efficiency.

[0068] Figure 7 is a cross-sectional view showing the top of the bundle in this embodiment.

[0069] As shown in Figure 7, the inlet header 22 is constructed by fixing a disc member 52 to the longitudinal end of a cylindrical pipe 51. The cylindrical pipe 51 has a tapered portion 51a formed around the entire circumference of the inner side of the end, as well as a fitting portion 51b. The inner diameter of the tapered portion 51a increases towards the end, while the inner diameter of the fitting portion 51b is constant in the axial direction. On the other hand, the disc member 52 has a tapered portion 52a formed around the entire circumference of the outer side, as well as a fitting portion 52b. The inner diameter of the tapered portion 52a decreases towards the fitting portion 52b, while the outer diameter of the fitting portion 52b is constant in the axial direction.

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

[0071] In this embodiment, the bundle 12 has the bent connection portion 24e of the heat transfer tube 24 connected to the end of the inlet header 22. That is, the inlet header 22 has a connecting hole 51d and a working hole 51e formed at the end of the cylindrical tube 51. The end of the bent connection portion 24e of the heat transfer tube 24 is inserted into the connecting hole 51d of the inlet header 22 and fixed in place. A plug (not shown) is also fitted into the working hole 51e. In this case, since the heat transfer tube 24 is connected to the inlet header 22 by the bent connection portion 24e, the influence of seal welding can be suppressed by positioning the connecting hole 51d and the working hole 51e as far away as possible from the tapered portion 51a of the cylindrical tube 51.

[0072] On the other hand, in conventional bundles, the straight connecting portion 24d of the heat transfer tube 24 is connected to the end of the inlet header 22. In this case, since the straight connecting portion 24d is not bent, the connection position of the straight connecting portion 24d to the inlet header 22 is closer to the end (disc member 52) than the connection position of the bent connecting portion 24e. In other words, the inlet header 22 needs to have the connecting hole 51d and the working hole 51e on the disc member 52 side of the cylindrical tube 51. As a result, the connecting hole 51d and the working hole 51e are close to the tapered portion 51a of the cylindrical tube 51. When the connecting hole 51d is close to the tapered portion 51a, seal welding becomes difficult when the straight connecting portion 24d is inserted into and fixed in the connecting hole 51d. Furthermore, if the working hole 51e interferes with the tapered portion 51a, when the disc member 52 is groove-welded to the cylindrical pipe 51, heat is more easily transferred to the working hole 51e, which may cause the working hole 51e to deform. 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 to 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. Of 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 side of the inlet header 22 and the outlet header 23 is offset 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 embodiment, the connecting portion 24e of the heat transfer tube 24 connected to the longitudinal end side of the inlet header 22 and outlet header 23 is offset and connected to the connecting portion 24d side of the adjacent heat transfer tube 24, thereby shortening the overall length of the inlet header 22 and outlet header 23. As a result, the bundle 12 can be made smaller and the heat exchange performance can be improved.

[0075] The bundle according to the second embodiment is the bundle according to the first embodiment, further comprising a bent connector 24e at the end of the longitudinal direction of at least the inlet header 22 and the outlet header 23. This allows the heat transfer tube 24 to be appropriately connected to the inlet header 22 and the outlet header 23 at a position offset from them by the bent connector 24e.

[0076] The bundle according to the third embodiment is a bundle according to the second embodiment, further comprising: a first linear connecting portion 24e1 that is linearly continuous with the straight portion 24a of the heat transfer tube 24; a second linear connecting portion 24e2 that is parallel to the straight portion 34a and connected to the inlet header 22 or outlet header 23; and a curved connecting portion 24e3 that connects the first linear connecting portion 24e1 and the second linear connecting portion 24e2. This allows the heat transfer tube 24 to be smoothly connected to the inlet header 22 or outlet header 23 by the curved connecting portion 24e.

[0077] The bundle according to the fourth embodiment is the bundle according to the third embodiment, further wherein the curved connecting portion 24e3 has an S-shape. This allows the first straight connecting portion 24e1 and the second straight connecting portion 24e2 to be smoothly connected by the curved connecting portion 24e3.

[0078] The bundle according to the fifth embodiment is a bundle according to any one of the second to fourth embodiments, further comprising a plurality of heat transfer tubes 24, wherein the straight sections 24a having fins are arranged at equal intervals with gaps in the longitudinal direction of the inlet header 22 and the outlet header 23, and 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 longitudinal middle section of the inlet header 22 and the outlet header 23 are straight connection portions 24d that are linearly continuous with the straight sections, and the distance between the bent connection portion 24e and the straight connection portion 24d is shorter than the distance between the straight connection portions 24d. This makes it possible to shorten the overall length of the inlet header 22 and the outlet header 23.

[0079] The heat exchanger according to the sixth embodiment comprises a duct casing 13 that forms an exhaust gas passage 14, and a bundle 12 disposed inside the duct casing 13. This makes it possible to miniaturize the bundle 12 and improve the heat exchange performance.

[0080] The flue gas treatment device according to the seventh embodiment includes a heat recovery device 101 that recovers a portion of the heat from the exhaust gas G, an electrostatic precipitator 102 that removes soot contained in the exhaust gas G after heat recovery, a desulfurization device 104 that removes sulfur oxides contained in the exhaust gas G after dust collection, and a reheating device 105 to which a heat exchanger 11 is applied for reheating the exhaust gas G after desulfurization. This makes it possible to miniaturize the bundle 12 and improve the heat exchange performance. [Explanation of Symbols]

[0081] 11 Heat exchanger 12 bundles 13 Duct casing 14 Exhaust gas passage 21 Casing 22 Entrance Header 23 Exit Header 24 heat transfer tubes 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 Flue gas treatment equipment 101 Heat Recovery System 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 Shut-off valve 123 Mist Eliminator 131 Circulation pump 132 Heater 133 Drain Tank 134 Shut-off valve L11 First heat transfer fluid circulation line L12 Second heat transfer fluid circulation line L13 Steam Line L14 Steam drain line L21, L23 First connection line L22, L24 Second connection line L31 Heat transfer medium supply line L32 Heat transfer fluid discharge line G exhaust gas

Claims

1. An inlet header to which the heat transfer medium is supplied, An outlet header from which the heat transfer fluid is discharged, Multiple heat transfer tubes connecting the inlet header and the outlet header, Equipped with, Of the connection portions of the multiple heat transfer tubes connected to the inlet header and the outlet header, at least the connection portion of the heat transfer tube connected to the longitudinal end side of the inlet header and the outlet header is offset and connected toward the adjacent heat transfer tube connection portion. bundle.

2. At least the connection portion of the heat transfer tube connected to the longitudinal end side of the inlet header and the outlet header is a bent connection portion. The bundle according to claim 1.

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

4. The aforementioned curved connecting portion has an S-shape. The bundle according to claim 3.

5. The plurality of heat transfer tubes are arranged with fins in straight sections, with gaps between them in the longitudinal direction of the inlet header and the outlet header, and are evenly spaced apart. Of the multiple heat transfer tubes connected to the inlet header and the outlet header, the heat transfer tubes connected to the longitudinal middle section of the inlet header and the outlet header are linear connection sections that are linearly continuous with the straight section, and the distance between the bent connection section and the linear connection section is shorter than the distance between the linear connection sections. The bundle according to claim 2.

6. A duct casing that forms an exhaust gas passage, The bundle according to claim 1, which is disposed inside the duct casing, A heat exchanger equipped with [the following features].

7. A heat recovery device that recovers some of the heat from exhaust gases, A dust collector for removing soot 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 described in claim 6 is applied for reheating the exhaust gas after desulfurization, A flue gas treatment device equipped with the following features.

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