Header, bundle, heat exchanger, and smoke exhaust treatment device

Abstract

To provide a header, a bundle, a heat exchanger, and a smoke exhaust treatment device that improve workability of plugging work.SOLUTION: A header comprising a supply / discharge part for a heat medium, and to which a longitudinal end part of a heat transfer tube is connected comprises a work hole provided at a position opposed to a position where the end part of the heat transfer tube is connected, a female screw part formed in an inner peripheral part of the work hole, and a header plug comprising a male screw part screwed to the female screw part of the work hole from the outside. The female screw part and the male screw part are parallel screws.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present disclosure relates to headers, bundles, heat exchangers, and flue gas treatment devices. [Background technology]

[0002] Exhaust 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 exhaust gas discharged from the boiler is removed by the electrostatic precipitator, and the sulfur dioxide gas contained in the exhaust gas is removed by the desulfurization unit. At this time, the heat recovery unit recovers heat from the exhaust gas. The reheating unit reheats the exhaust gas after desulfurization using the heat recovered by the heat recovery unit, suppressing the emission of white smoke.

[0003] A heat exchanger as a heat recovery device or a reheating device includes a casing, an inlet header, an outlet header, and a plurality of heat transfer tubes. The inlet header and the outlet header are fixed to the casing, and the plurality of heat transfer tubes are disposed inside the casing, with one end connected to the inlet header and the other end connected to the outlet header. Therefore, heat exchange occurs between the exhaust gas introduced into the casing from the inlet portion and the heat medium flowing inside the plurality of heat transfer tubes.

[0004] In the above-mentioned heat exchanger, the exhaust gas contains soot and dust, and the heat transfer tubes come into contact with the soot and dust contained in the exhaust gas, causing wear and possible leakage of the heat transfer medium. In addition, the exhaust gas contains sulfur oxides, and the heat transfer tubes are corroded by the influence of the leaked heat transfer medium. When the heat transfer tubes are damaged, the inlet and outlet of the damaged heat transfer tube are plugged to make them unusable. For example, Patent Document 1 describes such a heat exchanger. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-011959 Summary of the Invention [Problem to be solved by the invention]

[0006] When plugging a damaged heat transfer tube, a worker first uses a work tool to insert a plug into the inlet header through a work hole provided in the inlet header (or outlet header) and pushes it into the end of the heat transfer tube. The worker then inserts a welding torch through a work hole adjacent to the work hole through which the work tool has been inserted, and fixes the plug to the end of the heat transfer tube by welding. Since the worker must plug the heat transfer tube in this way in the narrow space inside the inlet header, there is a problem that the work is advanced and difficult. Furthermore, if the welding of the plug to the end of the heat transfer tube is insufficient, it is not possible to prevent leakage of the heat transfer medium.

[0007] The present disclosure is devised to solve the above-mentioned problems, and aims to provide a plugging tool for heat transfer tubes that improves the workability of plugging work, and a method for detecting leaks in heat exchangers, flue gas treatment devices, and heat transfer tubes. [Means for solving the problem]

[0008] In order to achieve the above-mentioned object, the header of the present disclosure has a heat medium supply and discharge section and is connected to a longitudinal end of a heat transfer tube, and comprises a work hole provided at a position opposite to the position where the end of the heat transfer tube is connected, a female thread portion formed on the inner circumference of the work hole, and a header plug having a male thread portion that screws into the female thread portion of the work hole from the outside, and the female thread portion and the male thread portion are parallel threads.

[0009] The bundle of the present disclosure also has the header.

[0010] The heat exchanger of the present disclosure also includes the bundle.

[0011] In addition, the flue gas treatment device of the present disclosure 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 that reheats the exhaust gas after desulfurization, and the heat exchanger is applied to at least one of the heat recovery device and the reheating device. Effect of the Invention

[0012] According to the header and bundle, heat exchanger, and flue gas treatment device of the present disclosure, the workability of plugging work can be improved. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of the flue gas treatment device of this embodiment. [Diagram 2] FIG. 2 is a schematic diagram showing the heat recovery device and the reheating device of this embodiment. [Diagram 3] FIG. 3 is a schematic diagram showing the heat exchanger of the present embodiment. [Figure 4] FIG. 4 is a cross-sectional view of the inlet header. [Diagram 5] FIG. 5 is a cross-sectional view taken along line VV of FIG. 4, illustrating the inlet header. [Figure 6] FIG. 6 is a cross-sectional view showing a plug mounting hole of the inlet header. [Figure 7] FIG. 7 is a cross-sectional view showing an inlet header to which the plugging jig of this embodiment is attached. [Figure 8] FIG. 8 is a cross-sectional view showing a header plug in the plugging jig. [Figure 9] FIG. 9 is a cross-sectional view showing the stopper plug of the stopper jig. [Figure 10] FIG. 10 is a cross-sectional view showing a method for plugging a heat transfer tube. [Figure 11] FIG. 11 is a cross-sectional view showing a method for plugging a heat transfer tube. [Figure 12] FIG. 12 is a cross-sectional view showing a method for plugging a heat transfer tube. [Figure 13]FIG. 13 is a cross-sectional view showing the inlet header with the plugging jig attached thereto. [Figure 14] FIG. 14 is a flowchart showing a method for detecting leakage from a heat transfer tube. [Figure 15] FIG. 15 is a schematic diagram for explaining a method for detecting leakage from a heat transfer tube. [Figure 16] FIG. 16 is a schematic diagram for explaining a method for detecting leakage from a heat transfer tube. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] 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 a configuration in which each embodiment is combined. In addition, the components in the embodiments include those that a person skilled in the art can easily imagine, those that are substantially the same, and those that are within the so-called equivalent range.

[0015] [Exhaust gas treatment equipment] FIG. 1 is a schematic diagram showing the configuration of the flue gas treatment device of this embodiment.

[0016] In this embodiment, as shown in FIG. 1, the flue gas treatment device 100 removes 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.

[0017] The flue gas treatment device 100 includes a heat recovery device 101, an electric dust collector 102, a blower (induced draft fan) 103, a desulfurization device 104, a reheating device 105, and a blower (desulfurization fan) 106. When the blowers 103 and 106 are driven, the exhaust gas G discharged from a boiler 111 is sent to a chimney 112 through the heat recovery device 101, the electric dust collector 102, the desulfurization device 104, and the reheating device 105. Note that a denitration device may be provided upstream of the heat recovery device 101.

[0018] 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 electric dust collector 102a, and a blower 103a, and the exhaust gas passage 121b is provided with a heat recovery device 101b, an electric dust collector 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 is provided with a desulfurization device 104 and a reheating device 105. The exhaust gas passage 121c is branched into two exhaust gas passages 121d and 121e on the downstream side. The exhaust gas passage 121d is provided with a blower 106a, and the exhaust gas passage 121e is provided with a blower 106b. The two exhaust gas passages 121d and 121e merge into an exhaust gas passage 121f at their downstream sides. The exhaust gas passage 121f is connected to the chimney 112. In addition, an exhaust gas passage 121g is provided to connect the upstream side of the desulfurization device 104 in the exhaust gas passage 121c to the exhaust gas passage 121f. An opening / closing valve 122 is provided in the exhaust gas passage 121g.

[0019] The heat recovery device 101 (101a, 101b) recovers heat from the exhaust gas G by exchanging heat between the exhaust gas G (about 140°C) 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 in the heat recovery device 101 is introduced into the electric dust collector 102 (102a, 102b). The electric dust collector 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 is a device for removing sulfur from limestone (CaCO 3 ) absorbs and removes sulfur oxides in exhaust gas G, and produces gypsum (CaSO ) as a by-product. 4 .2H 2 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 (about 50°C) desulfurized by the desulfurization device 104 is introduced into the reheating device 105 of the gas-gas heater. The reheating device 105 reheats the exhaust gas G with the heat recovered by the heat recovery device 101 in the process of circulating the heat medium between the heat recovery device 101 and the reheating device 105. 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. By driving the circulation pump 131, the heat medium of the reheating device 105 is returned to the heat recovery device 101 through the first heat medium circulation line L11. The second heat medium circulation line L12 is provided with a heater 132. The heat medium of the heat recovery device 101 is supplied to the reheating device 105 by the circulation pump 131 through the second heat medium circulation line L12. During this process, the heater 132 is operated as necessary 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 diffusing it and reducing the white smoke, and then releases it into the atmosphere from the chimney 112.

[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 heat exchangers of a complete countercurrent type. However, the heat recovery unit 101 and the reheating unit 105 may be heat exchangers of other types, such as a high-temperature preheating countercurrent type, a high-temperature preheating parallel current type, or a 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 disposed in the exhaust gas passage 121a (121b).

[0026] The high-temperature heat recovery section 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 first heat transfer tubes 151 have an end 151a located on the upstream side in the flow direction of the exhaust gas G connected to a first header 152, and an end 151b located on the downstream side in the flow direction of the exhaust gas G connected to a second header 153.

[0027] The medium temperature heat recovery section 142 is disposed 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 tubes 154. The second heat transfer tubes 154 are disposed in the exhaust gas passage 121a (121b) along the flow direction of the exhaust gas G. The second heat transfer tubes 154 have an end 154a located on the upstream side in the flow direction of the exhaust gas G connected to the first header 155, and an end 154b located on the downstream side in the flow direction of the exhaust gas G connected to the second header 156.

[0028] The low-temperature heat recovery section 143 is disposed 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 tubes 157. The third heat transfer tubes 157 are disposed in the exhaust gas passage 121a (121b) along the flow direction of the exhaust gas G. The third heat transfer tube 157 has an end 157a located on the upstream side in the flow direction of the exhaust gas G connected to the first header 158, and an end 157b located on the downstream side in the flow direction of the exhaust gas G 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 disposed in the exhaust gas passage 121c.

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

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

[0032] The low-temperature heating section 163 is disposed 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 disposed in the exhaust gas passage 121c along the flow direction of the exhaust gas G. The third heat transfer tubes 177 have an end 177a located on the downstream side in the flow direction of the exhaust gas G connected to the first header 178, and an end 177b located on the upstream side in the flow direction of the exhaust gas G 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. 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 the 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 the second connection line L22. In addition, 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 the 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 the 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 opening / closing valve 134 is provided on the steam line L13.

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

[0037] [Heat exchanger configuration] In this embodiment, the heat exchanger of the present invention will be described as being applied to the heat recovery device 101 and the reheating device 105 in the above-mentioned flue gas treatment device 100. However, the heat exchanger of the present invention is not limited to the heat recovery device 101 and the reheating device 105 in the flue gas treatment device 100.

[0038] FIG. 3 is a schematic diagram showing the heat exchanger of the present embodiment.

[0039] 3, the heat exchanger 11 (heat recovery unit 101 or reheating unit 105) includes one bundle 12. However, the heat exchanger 11 may include a plurality of bundles 12. That is, the bundle 12 corresponds to, for example, the high-temperature heat recovery section 141, the medium-temperature heat recovery section 142, and the low-temperature heat recovery section 143 constituting the heat recovery unit 101, or the high-temperature heating section 161, the medium-temperature heating section 162, and the low-temperature heating section 163 constituting the reheating unit 105.

[0040] The bundle 12 is disposed inside a duct casing 13. The duct casing 13 has a horizontally aligned rectangular cylindrical shape, and an exhaust gas passage 14 is defined inside. The exhaust gas passage (gas path) 14 is provided along the vertical direction, and the exhaust gas G flows along the vertical direction. However, the exhaust gas passage 14 is not limited to the vertical direction, and may be provided along the horizontal direction, and the exhaust gas G may flow along the horizontal direction.

[0041] 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 supported by the inner wall portion of the duct casing 13.

[0042] 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 arranged along the horizontal direction. 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 with a gap therebetween in the vertical direction. In this case, one horizontal side (the right side in FIG. 3) of the inlet header 22 and the outlet header 23 faces the exhaust gas passage 14, and the other horizontal side (the left side in FIG. 3) faces the outside of the exhaust gas passage 14.

[0043] The heat transfer tubes 24 are arranged along a horizontal direction. The heat transfer tubes 24 are arranged along a horizontal direction intersecting the longitudinal directions of the inlet header 22 and the outlet header 23. One longitudinal end of the heat transfer tubes 24 is connected to the inlet header 22, and the other longitudinal end 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 the heat transfer tubes 24 is connected to the side of the inlet header 22 facing the exhaust gas passage 14, and the interiors of the heat transfer tubes 24 are in communication with each other. The other end of the heat transfer tubes 24 is connected to the side of the outlet header 23 facing the exhaust gas passage 14, and the interiors of the heat transfer tubes 24 are in communication with each other.

[0044] A casing 21 is disposed on the outside of the bundle 12. The casing 21 is disposed so as to surround a plurality of heat transfer tubes 24, and has longitudinal ends connected to an inlet header 22 and an outlet header 23, and is supported by the inner wall portion of the duct casing 13. The casing 21 is open on the upstream side and downstream side in the flow direction (vertical direction) of the exhaust gas G.

[0045] A flange joint 32 having a connecting flange 31 on a side portion 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, so that the insides are in communication. The flange joint 32 is disposed at one end portion of the inlet header 22 in the longitudinal direction. A flange joint 34 having a connecting flange 33 on a side portion 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, so that the insides are in communication. The flange joint 34 is disposed at the other end portion of the outlet header 23 in the longitudinal direction.

[0046] The heat transfer tube 24 has 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 fixing spiral fins around an element tube. The plurality of first curved portions 24b and the plurality of second curved portions 24c are formed only by element tubes, and no fins are provided. The plurality of straight portions 24a are connected at one end to adjacent ones by the first curved portion 24b, and connected at the other end to adjacent ones by the second curved portion 24c. The heat transfer tube 24 is connected at one end of the straight portion 24a downstream in the flow direction of the exhaust gas G to the inlet header 22, and at one end of the straight portion 24a upstream in the flow direction of the exhaust gas G to the outlet header 23.

[0047] 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 vertical direction, which is the flow direction of the exhaust gas G. The multiple heat transfer tubes 24 form a heat transfer tube group by being arranged at intervals in the horizontal direction (direction perpendicular to the paper surface of FIG. 3) perpendicular to the flow direction of the exhaust gas G. That is, one ends of the multiple heat transfer tubes 24 are connected to the inlet header 22 at intervals in the longitudinal direction (horizontal direction), and the other ends are connected to the outlet header 23 at intervals in the longitudinal direction (horizontal direction).

[0048] The heat medium supply line L31 is made of piping and has a flange joint at one end. The flange joint 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 one end. The flange joint of the heat medium discharge line L32 is connected to a flange joint 34 of the outlet header 23 of the bundle 12.

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

[0050] 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.

[0051] The heat medium that has exchanged heat with the exhaust gas G flows from the heat transfer tubes 24 to the outlet header 23, and is discharged to the heat medium discharge line L32.

[0052] [Header configuration] Fig. 4 is a cross-sectional view of the inlet header, Fig. 5 is a VV cross-sectional view of the inlet header of Fig. 4, and Fig. 6 is a cross-sectional view of the plug mounting hole of the inlet header. Note that, although the inlet header 22 will be described below, the outlet header 23 has almost the same configuration.

[0053] 4 and 5, the inlet header 22 has a cylindrical pipe shape along the horizontal direction, and is fixed to the duct casing 13. The inlet header 22 is connected to the end of the heat transfer tube 24 on the side facing the exhaust gas passage 14. In this case, the inlet header 22 has a mounting hole 41 formed along the horizontal direction perpendicular to the longitudinal direction, and the end of the heat transfer tube 24 is inserted into the mounting hole 41 and fixed. At this time, one end of the heat transfer tube 24 is connected to the mounting hole 41 of the inlet header 22 by an expanded portion 42.

[0054] That is, the header 22 has a ring-shaped groove formed on the inner circumferential surface of the mounting hole 41. The outer diameter of the end of the heat transfer tube 24 is slightly smaller than the inner diameter of the mounting hole 41. The end of the heat transfer tube 24 is inserted into the mounting hole 41. Then, a tube expansion tool (not shown) is inserted into the heat transfer tube 24, and the pressurizing part is positioned inside the end of the heat transfer tube 24 inserted into the mounting hole 41. Here, the diameter of the end of the heat transfer tube 24 is expanded by the pressurizing part, so that a part of the end of the heat transfer tube 24 bulges and enters the groove of the mounting hole 41, and an expanded tube part 42 is formed.

[0055] Furthermore, the inlet header 22 has a working hole 43 formed on the side that does not face the exhaust gas passage 14, and a header plug 44 is detachably attached to the working hole 43. A plurality of working holes 43 and header plugs 44 are provided at intervals in the longitudinal direction of the inlet header 22. The working holes 43 and header plugs 44 are used when plugging the ends of the heat transfer tubes 24. Therefore, the multiple working holes 43 and header plugs 44 are provided radially opposite the ends of the multiple heat transfer tubes 24 connected to the inlet header 22.

[0056] As shown in FIG. 6, the inlet header 22 has a work hole 43 formed therein, penetrating radially through the inlet header 22 on the side not facing the exhaust gas passage 14. A female thread 43a is formed in the inner periphery of the work hole 43. The female thread 43a is a parallel thread with a helical thread. The inlet header 22 also has a recess 43b formed therein, continuous with the work hole 43 (female thread 43a) on the outer periphery. The recess 43b is ring-shaped, and has an inner diameter larger than the inner diameter of the work hole 43. The recess 43b is machined with high precision in the inlet header 22, since the flat portion of the annular shape becomes the sealing surface.

[0057] The header plug 44 has a header plug body 44a, a flange portion 44b, and a male thread portion 44c. The header plug body 44a is, for example, hexagonal in shape. The flange portion 44b is integral with the header plug body 44a and has an outer diameter larger than that of 44a. The male thread portion 44c is integral with 44a and the flange portion 44b and has an outer diameter substantially the same as that of 44a. The male thread portion 44c is a parallel thread having a helical thread. The male thread portion 44c can be screwed into the female thread portion 43a of the working hole 43.

[0058] The female thread 43a of the working hole 43 and the male thread 44c of the header plug 44 are parallel threads. In a tapered thread, the line connecting the crests of adjacent threads is angled with respect to the central axis of the thread. Therefore, in a tapered thread, the outer circumference of the thread gradually becomes thinner toward the tip. On the other hand, in a parallel thread, the line connecting the crests of adjacent threads is parallel to the central axis of the thread. In a parallel thread, the outer circumference of the thread is the same toward the tip. Therefore, by adopting a parallel thread, it is possible to seal with the surface at the position where the male thread and the female thread are screwed together, and the sealing performance can be improved compared to a tapered thread. In addition, if the male thread 44c of the header plug 44 is a tapered thread, a gap will occur between the outer surface of the inlet header 22 and the header plug 44, and there is a risk that the outer surface of the inlet header 22 will corrode.

[0059] The header plug 44 is attached by screwing the male threaded portion 44c into the female threaded portion 43a of the working hole 43, and the working hole 43 is closed to stop water leakage. At this time, a metal gasket (sealing member) 45 is attached between the header plug 44 and the working hole 43. The metal gasket 45 has an annular shape and is attached to the recess 43b of the inlet header 22. When the male threaded portion 44c of the header plug 44 is screwed into the female threaded portion 43a of the working hole 43, the flange portion 44b of the header plug 44 comes into contact with the metal gasket 45, and the metal gasket 45 is pressed against the flat portion (sealing surface) of the recess 43b. Note that the flange portion 44b of the header plug 44 may be eliminated, and the header plug body 44a may come into contact with the metal gasket 45. Then, the flange portion 44b of the header plug 44, the metal gasket 45, and the recess 43b are tightly attached with a predetermined pressure. Therefore, surface friction acts between the flange portion 44b of the header plug 44, the metal gasket 45, and the recess 43b, making it possible to waterproof the working hole 43 and also preventing the header plug 44 from loosening.

[0060] [Stopping tool] FIG. 7 is a cross-sectional view showing an inlet header to which the plugging jig of this embodiment is attached, FIG. 8 is a cross-sectional view showing a header plug in the plugging jig, and FIG. 9 is a cross-sectional view showing a plug in the plugging jig.

[0061] The heat transfer tubes 24 may corrode and become damaged over long-term use due to contact with the exhaust gas G, which may cause leakage of the heat medium. Therefore, during regular inspections in which the operation of the heat exchanger 11 is stopped, a leak inspection of the heat transfer tubes 24 is performed, and any heat transfer tubes 24 that have leaks are plugged to make them unusable.

[0062] 7, the plugging jig 50 for a heat transfer tube is used to close the working hole 43 and the end of the heat transfer tube 24 from the outside of the duct casing 13. The plugging jig 50 for a heat transfer tube includes a plug plug 51, a header plug 52, a connecting shaft 53, and a leak prevention lid 54.

[0063] The stop plug 51 can be fitted into the end of the heat transfer tube 24 to close it. The header plug 52 can be fitted into the working hole 43 to close it. The stop plug 51 is connected to one end of the connecting shaft 53, and the header plug 52 is supported on the other end side so as to be movable axially. In this case, the header plug 52 and the connecting shaft 53 are threadedly engaged with each other and are relatively movable in the axial direction. The leak prevention lid 54 is screwed onto the header plug 52 from the outside of the inlet header 22.

[0064] As shown in Figs. 7 to 9, the stop plug 51 has a stop plug body 61 and a fixing portion 62. The stop plug body 61 is preferably formed of a truncated cone shape and made of silicone rubber. However, the stop plug body 61 is not limited to silicone rubber, and may be made of any material having sealing properties. The stop plug body 61 has a through hole 63 through which one end of the connecting shaft 53 passes. The fixing portion 62 is disposed on the tip side of the stop plug body 61 where the outer diameter is reduced. The fixing portion 62 has an outer diameter smaller than that of the stop plug body 61, and is preferably a hexagonal nut, for example. The fixing portion 62 is fixed by screwing one end of the connecting shaft 53 that passes through the through hole 63 of the stop plug body 61.

[0065] The header plug 52 has a header plug body 71, a flange portion 72, a male thread portion 73, a first female thread portion 74, and a second female thread portion 75. The header plug body 71 has, for example, a hexagonal shape. The flange portion 72 is provided integrally with the header plug body 71, and has an outer diameter larger than the outer diameter of the header plug body 71. The male thread portion 73 is provided integrally with the header plug body 71 and the flange portion 72, and has an outer diameter substantially the same as the outer diameter of the header plug body 71. The male thread portion 73 is a parallel thread whose threads are helical. The male thread portion 73 can be screwed into the female thread portion 43a of the working hole 43 of the inlet header 22.

[0066] The header plug 52 has a cylindrical shape and has a first female thread 74 and a second female thread 75 on the inner periphery. The first female thread 74 is formed on the tip end side of the header plug 52, and the second female thread 75 is formed on the base end side of the header plug 52. The second female thread 75 has an inner diameter larger than the inner diameter of the first female thread 74. The first female thread 74 and the second female thread 75 are parallel threads with helical threads. The first female thread 74 is screwed with the other end of the connecting shaft 53. The first female thread 74 and the second female thread 75 are in communication. The header plug 52 has a flat portion 76 formed at a step between the first female thread 74 and the second female thread 75, which functions as a seal surface. The flat portion 76 is in an annular shape.

[0067] The connecting shaft 53 has a screw shaft 81, a plug retainer 82, and a locking portion 83. The screw shaft 81 has a predetermined length (at least a length longer than the inner diameter of the inlet header 22) and is configured by forming a screw on the outer periphery of a cylindrical shaft. The screw shaft 81 is a parallel screw with a helical thread. The other end of the screw shaft 81 screws into the first female thread portion 74 of the header plug 52. The plug retainer 82 is fixed to one end side of the screw shaft 81. The plug retainer 82 is fixed at a position shifted a predetermined length from one end of the screw shaft 81 toward the other end side. The plug retainer 82 is disc-shaped and has an outer diameter approximately the same as the outer diameter of the stopper plug body 61.

[0068] One end of the connecting shaft 53 passes through the through hole 63 of the stopper plug body 61 of the stopper plug 51 and is screwed into the fixed part 62. At this time, the plug holder 82 holds the stopper plug body 61 in the axial direction together with the fixed part 62. In other words, the plug holder 82 restricts the axial movement of the stopper plug body 61 relative to the connecting shaft 53.

[0069] The locking portion 83 is fixed to the other end side of the screw shaft 81. The locking portion 83 extends a predetermined length from the other end of the screw shaft 81. The locking portion 83 has, for example, a rectangular prism shape. A tool (not shown) can be locked to the locking portion 83 to rotate the connecting shaft 53.

[0070] The leak prevention lid 54 has a lid body 91, a male thread portion 92, and a space portion 93. The lid body 91 has, for example, a hexagonal shape. The male thread portion 92 is provided integrally with the lid body 91, and has an outer diameter smaller than that of the lid body 91. The male thread portion 92 is a parallel screw having a helical thread. The male thread portion 92 can be screwed into the second female thread portion 75 of the header plug 52. The space portion 93 is provided so as to open to the tip end side of the male thread portion 92. In other words, the male thread portion 92 has a cylindrical shape, thereby forming the space portion 93. The space portion 93 prevents contact with the other end (locking portion 83) of the connecting shaft 53 that penetrates the header plug 52.

[0071] 7, when the heat transfer tube plugging jig 50 is attached to the inlet header 22, the plug 51 fits into and closes the end of the heat transfer tube 24, and the header plug 52 screws into and closes the working hole 43 of the inlet header 22. At this time, the plug 51 and the header plug 52 are connected by a connecting shaft 53, which prevents the plug 51 from coming off the end of the heat transfer tube 24.

[0072] In addition, a metal gasket (sealing member) 45 is attached between the header plug 52 and the recess 43b of the inlet header 22. The flange portion 72 of the header plug 52, the metal gasket 45, and the recess 43b are in close contact with each other with a predetermined pressure. Therefore, surface friction acts between the flange portion 72 of the header plug 52, the metal gasket 45, and the recess 43b, preventing the header plug 52 from loosening. The flange portion 72 of the header plug 52 may be eliminated, and the header plug body 71 may contact the metal gasket 45. Furthermore, the leak prevention cover 54 is screwed into the second female thread portion 75 of the header plug 52, and the tip surface is pressed against and in close contact with the flat portion 76 between the first female thread portion 74 and the second female thread portion 75 of the header plug 52, thereby sealing the working hole 43.

[0073] [How to plug heat transfer tubes] 10 to 12 are cross-sectional views showing a plugging method for a heat transfer tube, and FIG. 13 is a cross-sectional view showing an inlet header with a plugging jig attached thereto.

[0074] 10, first, the plugging jig 50 for heat transfer tubes is attached to the inlet header 22. That is, with the plug 51 attached to the tip end of the connecting shaft 53 and the header plug 52 attached to the base end, the plug 51 is inserted into the inlet header 22 from the outside of the inlet header 22 through the working hole 43 using the connecting shaft 53. The header plug 52 is then fitted into the working hole 43 and rotated to screw it into the working hole 43.

[0075] Next, the stop plug 51 is fitted into the end of the heat transfer tube 24. That is, the header plug 52 is attached to the inlet header 22 by screwing into the working hole 43. In this state, a tool (not shown) is engaged with the engaging portion 83 of the connecting shaft 53, and the connecting shaft 53 is rotated relative to the header plug 52, thereby moving the stop plug 51 forward together with the connecting shaft 53, and as shown in Fig. 11, the stop plug 51 is fitted into the end of the heat transfer tube 24. Here, by rotating the connecting shaft 53 up to a preset predetermined load, the stop plug 51 is fitted into the end of the heat transfer tube 24 with a predetermined pressure, and the end of the heat transfer tube 24 can be blocked (sealed).

[0076] 12, finally, the leak prevention lid 54 is attached to the header plug 52. That is, the leak prevention lid 54 is fitted to the header plug 52, and the leak prevention lid 54 is rotated so that the leak prevention lid 54 fits tightly to the header plug 52. By fitting the leak prevention lid 54 to the header plug 52, leakage of water from the working hole 43 is suppressed.

[0077] 13, when the heat transfer tube plugging tool 50 is attached to the inlet header 22 to plug the ends of the heat transfer tubes 24, only the header plug 44 that faces the end of the target heat transfer tube 24 is removed. In other words, there is no need to remove the header plugs 44 adjacent to the header plug 44 that faces the end of the target heat transfer tube 24, making the work easier and shortening the work time.

[0078] [Method of detecting leaks in heat transfer tubes] FIG. 14 is a flowchart showing a method for detecting leakage from a heat transfer tube, and FIGS. 15 and 16 are schematic diagrams for explaining the method for detecting leakage from a heat transfer tube.

[0079] As shown in Figs. 14 and 15, in step S11, water inside the inlet header 22, the outlet header 23, and the heat transfer tubes 24 is discharged from the bundle 12 to be inspected for leaks in the heat exchanger 11. In step S12, all the header plugs 44 attached to the inlet header 22 are removed, and all the header plugs 44 attached to the outlet header 23 are removed. In step S13, a heat transfer tube stopper tool 50 is attached to the working holes 43 of the inlet header 22 and the outlet header 23 from which the header plugs 44 have been removed. That is, the heat transfer tube stopper tool 50 is attached to each header 22, 23, one end and the other end of the heat transfer tube 24 are closed with the stopper plugs 51, and the working hole 43 is closed with the header plug 52 and the leak prevention cover 54. The nozzles 35, 36 provided in the inlet header 22 and the outlet header 23 are also closed.

[0080] The heat exchanger 11 has a plurality of heat transfer tubes 24, and one end and the other end of all the heat transfer tubes 24 are closed by the stop plug 51 of the heat transfer tube stopper jig 50, and all the working holes 43 are closed by the header plug 52 and the leak prevention lid 54, so that the plurality of heat transfer tubes 24 are individually maintained in a closed state. As shown in Figs. 14 and 16, in step S14, from this state, the closing of the end of the heat transfer tube 24 by the stop plug 51 of the heat transfer tube stopper jig 50 attached to the outlet header 23 is released for one of the plurality of heat transfer tubes 24. That is, the leak prevention lid 54 is removed from the header plug 52 by the heat transfer tube stopper jig 50 attached to the outlet header 23, and the connecting shaft 53 is rotated in the reverse direction to remove the stop plug 51 from the end of the heat transfer tube 24. Then, the leak prevention lid 54 is attached to the header plug 52 again. At this time, the tip surface of the leak prevention cover 54 presses against the flat portion 76 and comes into close contact with it, thereby preventing the pressurized air from leaking from the female thread portion 74 during the processing of step S15.

[0081] In step S15, the pressurizing pipe 37 is connected to the nozzle 36, and pressurized air is supplied to one of the heat transfer tubes 24 through the outlet header 23 to pressurize it. Then, the pressure inside one of the heat transfer tubes 24 is continuously measured by the pressure gauge 38 provided in the pressurizing pipe 37. In step S16, based on the measurement result of the pressure gauge 38, it is determined whether or not the pressure inside the heat transfer tube 24 has decreased. Here, if it is determined that the pressure inside the heat transfer tube 24 has not decreased (No), in step S17, it is determined that there is no leak in the heat transfer tube 24. On the other hand, if it is determined that the pressure inside the heat transfer tube 24 has decreased (Yes), in step S18, it is determined that there is a leak in the heat transfer tube 24. After the leak determination is completed, in step S19, the supply of pressurized air from the outlet header 23 to the heat transfer tube 24 is stopped, and the heat transfer tube stopper jig 50 attached to the outlet header 23 is again operated to close the end of the heat transfer tube 24 with the stopper plug 51.

[0082] When the leak test for one heat transfer tube 24 is completed, a leak test for another heat transfer tube 24 is carried out in the same manner.

[0083] [Effects of this embodiment] The header of the first embodiment has a heat medium supply and discharge section and is connected to the longitudinal end of the heat transfer tube 24 in the header 22, 23. The header includes a work hole 43 provided at a position opposite to the position where the end of the heat transfer tube 24 is connected, a female thread portion 43a formed on the inner periphery of the work hole 43, and a header plug 44 having a male thread portion 44c that screws into the female thread portion 43a of the work hole 43 from the outside, and the female thread portion 43a and the male thread portion 44c are parallel threads.

[0084] According to the header of the first aspect, the header plug 44 can be easily attached and detached because the male thread portion 44c screws into the female thread portion 43a of the working hole 43, and because the threads are parallel to each other, fastening is completed when a part of the header plug 44 abuts against the outer periphery of the header. Also, because the female thread portion 43a is formed on the inner periphery of the working hole 43, for example, a heat transfer tube plugging tool 50 can be easily attached. As a result, the plugging work for the heat transfer tube can be facilitated, shortening the work time and improving the workability of the plugging work.

[0085] The header according to the second embodiment is the header according to the first embodiment, further comprising a header plug 44 having a header plug body 44a and a male thread portion 44c whose outer diameter is smaller than that of the header plug body 44a, and the header plug body 44a contacts the outer periphery of the header via a ring-shaped metal gasket (sealing member) 45. Thus, the metal gasket 45 is interposed between the header plug body 44a and the outer periphery of the header, thereby improving water blocking performance.

[0086] The header according to the third embodiment is the header according to the first embodiment, further comprising a header plug 44 having a header plug body 44a, a flange portion 44b whose outer diameter is larger than that of the header plug body 44a, and a male thread portion 44c whose outer diameter is smaller than that of the flange portion 44b, and the flange portion 44b comes into contact with the outer periphery of the header via a ring-shaped metal gasket (sealing member) 45. Thus, the metal gasket 45 is interposed between the flange portion 44b and the outer periphery of the header, thereby improving water blocking performance.

[0087] The header according to the fourth aspect is the header according to the second or third aspect, further comprising a recess 43b located around the working hole 43 on the outer periphery of the header, and a metal gasket 45 is disposed in the recess 43b. This makes it easy to position the metal gasket 45 relative to the outer periphery of the header.

[0088] The header according to the fifth embodiment is the header according to the fourth embodiment, and further, the flat portion of the recess 43b with which the metal gasket 45 comes into contact is a sealing surface that has been machined with high precision. As a result, the metal gasket 45 comes into contact with the sealing surface, thereby further improving the water blocking performance.

[0089] The header according to the seventh aspect is the header according to any one of the first to sixth aspects, and further includes a header plug 52 provided with a stopper plug 51 that closes the end of the heat transfer tube 24 that is connected at a position facing the working hole 43. In this way, by fitting the header plug 52 into the working hole 43, the end of the heat transfer tube 24 can be fitted into the stopper plug 51 to be closed.

[0090] The header according to the eighth aspect is the header according to any one of the first to seventh aspects, and further, the inner diameter of the working hole 43 is larger than the inner diameter of the end of the heat transfer tube 24 that is connected at a position facing the working hole 43. This allows a stopper plug 51 to be attached to the end of the heat transfer tube 24 from the outside through the working hole 43.

[0091] The bundle according to the eighth embodiment has headers 22, 23. This facilitates plugging work for the heat transfer tubes, shortens the work time, and improves the workability of the plugging work.

[0092] The heat exchanger according to the ninth embodiment has the bundle 12. This facilitates plugging work of the heat transfer tubes, shortens the work time, and improves the workability of the plugging work.

[0093] The flue gas treatment device according to the tenth aspect includes a heat recovery device 101 that recovers a portion of the heat of the flue gas G, an electric dust collector 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 reheats the desulfurized flue gas G, and the heat exchanger 11 is applied to at least one of the heat recovery device 101 and the reheating device 105. This makes it possible to facilitate the plugging operation of the heat transfer tubes, shorten the operation time, and improve the workability of the plugging operation.

[0094] In the above-described embodiment, the heat exchanger 11 has the inlet header 22 and the outlet header 23 arranged along the horizontal direction, and the ends of the multiple heat transfer tubes 24 arranged along the horizontal direction intersecting the longitudinal direction of the inlet header 22 and the outlet header 23 are connected to the inlet header 22 and the outlet header 23, respectively. However, the heat exchanger 11 is not limited to such a configuration. The heat exchanger 11 may have a configuration in which the inlet header 22 and the outlet header 23 are arranged along the vertical direction, and the ends of the multiple heat transfer tubes 24 arranged along the horizontal direction are connected to the inlet header 22 and the outlet header 23, respectively. The heat exchanger 11 may also have a configuration in which the inlet header 22 and the outlet header 23 are arranged along the horizontal direction, and the upper ends of the multiple heat transfer tubes 24 arranged along the vertical direction are connected to the inlet header 22 and the outlet header 23, respectively. [Explanation of symbols]

[0095] 11 Heat exchanger 12 Bundles 13 Duct casing 14 Exhaust gas passage 21 Casing 22 Inlet Header 23 Exit Header 24 Heat transfer tube 31,33 Connecting flange 32,34 Flange joint 35,36 Nozzle 41 Mounting hole 42 Expanded section 43 Working hole 44 Header plug 44a Header plug body 44b Flange part 44c Male thread 45 Metal gasket 50 Heat transfer tube stopper jig 51 Stop plug 52 Header plug 53 Connecting shaft 54 Leak-proof lid 61 Stop plug body 62 Fixed part 63 Through hole 71 Header plug body 72 Flange 73 Male thread 74 First female thread 75 Second female thread 76 Plane part 81 Screw shaft 82 Plug holder 83 Locking part 91 Lid body 92 Male thread 93 Space section 100 Smoke treatment equipment 101 Heat recovery equipment 102 Electrostatic Precipitator 103 Blower 104 Desulfurization equipment 105 Reheating device 106 Blower 111 Boiler 112 Chimney 121a, 121b, 121c, 121d, 121e, 121f, 121g Exhaust gas passage 122 On-off valve 123 Mist Eliminator 131 Circulation Pump 132 Heater 133 Drain tank 134 On-off valve L11 First heat medium circulation line L12 Second heat medium circulation line L13 Steam Line L14 Steam drain line L21, 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. A header having a heat transfer medium supply and discharge portion and connected to longitudinal ends of heat transfer tubes, A working hole provided at a position opposite to a position where an end of the heat transfer tube is connected; A female thread portion formed on an inner periphery of the working hole; a header plug having a male thread portion that is screwed into the female thread portion of the work hole from the outside; Equipped with The female thread portion and the male thread portion are parallel threads. header.

2. the header plug has a header plug body and the male thread portion having an outer diameter smaller than the outer diameter of the header plug body, and the header plug body contacts an outer periphery of the header via a seal member having an annular shape; The header of claim 1 .

3. the header plug has a header plug body, a flange portion having an outer diameter larger than that of the header plug body, and the male thread portion having an outer diameter smaller than that of the flange portion, and the front flange portion contacts an outer periphery of the header via a seal member having an annular shape; The header of claim 1 .

4. a recess is provided around the work hole in an outer periphery of the header, and the seal member is disposed in the recess; 4. A header according to claim 2 or claim 3.

5. The flat surface of the recess with which the seal member comes into contact is a seal surface that has been machined with high precision.

5. The header of claim 4.

6. The header plug is provided with a stopper plug that closes an end of a heat transfer tube that is connected to a position facing the work hole. The header of claim 1 .

7. The inner diameter of the working hole is larger than the inner diameter of the end of the heat transfer tube connected to the position opposite the working hole. The header of claim 1 .

8. A bundle comprising the header of claim 1.

9. A heat exchanger comprising the bundle of claim 8.

10. 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 that reheats the exhaust gas after desulfurization; Equipped with The heat exchanger according to claim 9 is applied to at least one of the heat recovery device and the reheating device. Smoke treatment equipment.

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