JP2022052283A - Heat exchanger and flue gas treatment device - Google Patents

Abstract

To improve workability of maintenance work of heat transfer pipes and inhibit stop of flue gas treatment in a heat exchanger and a flue gas treatment device.SOLUTION: A heat exchanger includes: a housing; heat transfer pipes disposed in the housing; a first header which is fixed to the housing and to which one end part of the heat transfer pipes is connected; a second header which is fixed to the housing and to which the other end part of the heat transfer pipes is connected; a first access part for access to a connection portion of the heat transfer pipes in the first header from the outside of the first header; and a second access part for access to a connection portion of the heat transfer pipes in the second header from the outside of the second header.SELECTED DRAWING: Figure 8

Description

The present disclosure relates to a heat exchanger used in a flue gas treatment apparatus and the like, and a flue gas treatment apparatus including a heat exchanger.

The smoke exhaust treatment device provided in a thermal power generation facility or the like is composed of a heat recovery device, an electrostatic precipitator, a scrubbering device, a reheating device, and the like. In the flue gas treatment device, the exhaust gas discharged from the boiler is removed from the soot and dust contained by the electrostatic precipitator, and the sulfur dioxide gas contained by the desulfurization device is removed. At this time, the heat recovery device recovers heat from the exhaust gas. The reheating device reheats the exhaust gas after desulfurization by the heat recovered by the heat recovery device, and suppresses the emission of white smoke.

The reheating device has a plurality of heat transfer tubes arranged in the exhaust gas passage. The reheating device heats the exhaust gas and raises the temperature by flowing a high-temperature heat medium through a plurality of heat transfer tubes and exchanging heat between the heat medium and the exhaust gas flowing through the exhaust gas passage. As a complete countercurrent method, the reheating device causes the heat medium to flow in the heat transfer tube so as to face the flow direction of the exhaust gas flowing through the exhaust gas passage. That is, heat exchange is efficiently performed by making the flow direction of the exhaust gas flowing through the exhaust gas passage and the flow direction of the heat medium flowing in the heat transfer tube opposite to each other.

However, the exhaust gas flowing into the reheating device contains a mist containing corrosive impurities. Therefore, in the heat transfer tube arranged on the inlet side of the reheating device, the event of adhesion and evaporation of the mist containing corrosive impurities repeatedly occurs. Then, the heat transfer tube is repeatedly concentrated and dried and wet with corrosive impurities, which may cause early corrosion. As a solution to such a problem, for example, there is one described in Patent Document 1 below. The heat exchanger described in Patent Document 1 is a high-temperature preheating countercurrent system, and by providing a preheating section on the upstream side of the high-temperature heating section and the low-temperature heating section in the flow direction of the exhaust gas, the inlet side of the reheating device is provided. It raises the temperature of the exhaust gas in the above and suppresses the premature corrosion of the heat transfer tube.

Japanese Patent No. 6632198

In the reheating device used in the smoke exhaust treatment device described above, a fin tube having fins fixed to the outer peripheral portion of the raw tube is applied to the heat transfer tube. The fin tube is liable to be corroded due to the adhesion of the mist containing corrosive impurities contained in the exhaust gas, and the raw tube may be damaged to cause leakage of the heat medium. If the heat transfer tube (fin tube) is damaged, the inlet and outlet of the damaged heat transfer tube will be stopped and disabled. The work of stopping the heat transfer tube needs to be carried out by disassembling the housing of the reheating device, which is a large-scale work, and there is a problem that the work time becomes long and the work cost increases. In addition, it is necessary to stop the flue gas treatment device during the work of stopping the heat transfer tube, which makes the flue gas treatment difficult.

The present disclosure has been made to solve the above-mentioned problems, and an object of the present invention is to provide a heat exchanger and a flue gas treatment apparatus for improving the workability of maintenance work of a heat transfer tube and suppressing the stoppage of flue gas treatment work. And.

In the heat exchanger of the present disclosure for achieving the above object, a housing, a plurality of heat transfer tubes arranged inside the housing, and one end of the plurality of heat transfer tubes fixed to the housing are connected to each other. A first header, a second header fixed to the housing and connected to the other ends of the plurality of heat transfer tubes, and the plurality of heat transfer tubes from the outside of the first header to the inside of the first header. A first access unit for accessing the connecting portion and a second access unit for accessing the connecting portion of the plurality of heat transfer tubes inside the second header from the outside of the second header are provided.

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

According to the heat exchanger and the flue gas treatment apparatus of the present disclosure, it is possible to improve the workability of the maintenance work of the heat transfer tube and suppress the stoppage of the flue gas treatment work.

FIG. 1 is a schematic configuration diagram showing a flue gas treatment apparatus of this embodiment. FIG. 2 is a schematic configuration diagram showing a reheating device as a heat exchanger of the present embodiment. FIG. 3 is a schematic plan view showing the reheating device. FIG. 4 is a schematic front view showing the reheating device. FIG. 5 is a schematic plan view showing a high temperature heating unit. FIG. 6 is a schematic side view showing a high temperature heating unit. FIG. 7 is a schematic view showing the support structure of the first heat transfer tube. FIG. 8 is a cross-sectional view showing the first header. FIG. 9 is a cross-sectional view showing a connecting structure of the first header and the first heat transfer tube.

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

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

In the present embodiment, as shown in FIG. 1, the smoke exhaust treatment device 100 is in a process in which the exhaust gas (smoke exhaust) G discharged from the boiler 111 is discharged from the chimney 112 in various power generation plants and factories. , Soot and sulfur oxides (SOx) contained in the exhaust gas G are removed.

The smoke exhaust treatment device 100 includes a heat recovery device 101, an electrostatic precipitator 102, a blower device (attracting blower) 103, a desulfurization device 104, a reheating device 105, and a blower device (desulfurization blower) 106. To prepare for. By driving the blowers 103 and 106, 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. A denitration device may be provided on the upstream side of the heat recovery device 101.

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

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 (water or the like). The exhaust gas G (about 90 ° C.) heat recovered by the heat recovery device 101 is introduced into the electrostatic precipitator 102 (102a, 102b). The electrostatic precipitator 102 removes dust from the exhaust gas G.

The exhaust gas G from which dust has been removed by the electrostatic precipitator 102 is introduced into the desulfurization device 104. The desulfurization apparatus 104 absorbs and removes sulfur oxides in the exhaust gas G with limestone (CaCO ₃ ) to produce gypsum (CaSO _{4.2H 2} O) as a by-product. The desulfurization apparatus 104 has a mist eliminator 123. The mist eliminator 123 removes mist from the exhaust gas G after desulfurization.

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

The temperature of the exhaust gas G is lowered by being desulfurized by the desulfurization apparatus 104, and if it remains at a low temperature, it is difficult to diffuse and there is a possibility that it becomes white smoke. The reheating device 105 raises the temperature (about 90 ° C.) by reheating the exhaust gas G for the purpose of diffusion and reduction of white smoke, and releases the exhaust gas G to the atmosphere from the chimney 112.

[Structure of reheating device]
FIG. 2 is a schematic configuration diagram showing a reheating device as a heat exchanger of the present embodiment. In the present embodiment, the heat exchanger of the present invention will be described by applying it to the reheating device 105 in the smoke exhaust treatment device 100 described above.

As shown in FIG. 2, the reheating device 105 is a heat exchanger of a complete countercurrent system, but may be a heat exchanger of a high temperature preheat countercurrent system or another system.

The reheating device 105 includes a high temperature heating unit 11, a medium temperature heating unit 12, and a low temperature heating unit 13. The high temperature heating unit 11, the medium temperature heating unit 12, and the low temperature heating unit 13 are arranged in the exhaust gas passage 121c.

The high temperature heating unit 11 has a plurality of first heat transfer tubes 21. The first heat transfer tube 21 is arranged in the exhaust gas passage 121c along the flow direction of the exhaust gas G. In the first heat transfer tube 21, the end portion 21a located on the downstream side in the flow direction of the exhaust gas G is connected to the first header 22, and the end portion 21b located on the upstream side in the flow direction of the exhaust gas G is connected to the second header 23. Be concatenated.

The medium temperature heating unit 12 is arranged on the upstream side of the high temperature heating unit 11 in the flow direction of the exhaust gas G. The medium temperature heating unit 12 has a plurality of second heat transfer tubes 31. The second heat transfer tube 31 is arranged in the exhaust gas passage 121c along the flow direction of the exhaust gas G. In the second heat transfer tube 31, the end portion 31a located on the downstream side in the flow direction of the exhaust gas G is connected to the first header 32, and the end portion 31b located on the upstream side in the flow direction of the exhaust gas G is connected to the second header 33. Be concatenated.

The low temperature heating unit 13 is arranged on the upstream side in the flow direction of the exhaust gas G from the medium temperature heating unit 12. The low temperature heating unit 13 has a plurality of third heat transfer tubes 41. The third heat transfer tube 41 is arranged in the exhaust gas passage 121c along the flow direction of the exhaust gas G. In the third heat transfer tube 41, the end portion 41a located on the downstream side in the flow direction of the exhaust gas G is connected to the first header 42, and the end portion 41b located on the upstream side in the flow direction of the exhaust gas G is connected to the second header 43. Be concatenated.

The upstream end of the second heat medium circulation line L12 is connected to the heat recovery device 101, and the downstream end is connected to the first header 22 of the high temperature heating unit 11. The downstream end of the first heat medium circulation line L11 is connected to the heat recovery device 101, and the upstream end is connected to the second header 43 of the low temperature heating unit 13. The second header 23 of the high temperature heating unit 11 and the first header 32 of the medium temperature heating unit 12 are connected to each other from the first connection line L21. The second header 33 of the medium temperature heating unit 12 and the first header 42 of the low temperature heating unit 13 are connected to each other from the second connection line L22.

Further, 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. Then, a steam line L13 is provided from the steam supply source (not shown) to the heater 132 and the drain tank 133, and the steam drain line L14 is provided in the drain tank 133. The steam line L13 is provided with an on-off valve 134.

Therefore, the heat-recovered high-temperature heat medium is supplied from the second heat medium circulation line L12 to the downstream end 21a in the flow direction of the exhaust gas G in the first heat transfer tube 21 of the high-temperature heating unit 11. The heat medium of the first heat transfer tube 21 is from the upstream end 21b in the flow direction of the exhaust gas G to the downstream end in the flow direction of the exhaust gas G in the second heat transfer tube 31 of the medium temperature heating section 12 by the first connection line L21. It is supplied to the unit 31a. The heat medium of the second heat transfer tube 31 is from the upstream end 31b in the flow direction of the exhaust gas G to the downstream end in the flow direction of the exhaust gas G in the third heat transfer tube 41 of the low temperature heating unit 13 by the second connection line L22. It is supplied to the unit 41a. The heat medium of the third heat transfer tube 41 is discharged from the upstream end 41b in the flow direction of the exhaust gas G to the first heat medium circulation line L11.

FIG. 3 is a schematic plan view showing the reheating device, and FIG. 4 is a schematic front view showing the reheating device.

The reheating device 105 includes a first bundle 51, a second bundle 52, and a third bundle 53. The first bundle 51 is composed of a high temperature heating unit 11, the second bundle 52 is composed of a medium temperature heating unit 12, and the third bundle 53 is composed of a low temperature heating unit 13. In the first bundle 51, a plurality of first heat transfer tubes 21 are arranged inside the first housing 54, and in the second bundle 52, a plurality of second heat transfer tubes 31 are arranged inside the second housing 55. In the bundle 53, a plurality of third heat transfer tubes 41 are arranged inside the third housing 56.

In the high temperature heating unit 11, the first header 22 is fixed to the downstream side in the flow direction of the exhaust gas G in the first housing 54 of the first bundle 51, and the second header 23 is the first housing 54 of the first bundle 51. It is fixed to the upstream side in the flow direction of the exhaust gas G in. In the medium temperature heating unit 12, the first header 32 is fixed to the downstream side in the flow direction of the exhaust gas G in the second housing 55 of the second bundle 52, and the second header 33 is the second housing 55 of the second bundle 52. It is fixed to the upstream side in the flow direction of the exhaust gas G in. In the low temperature heating unit 13, the first header 42 is fixed to the downstream side in the flow direction of the exhaust gas G in the third housing 56 of the third bundle 53, and the second header 43 is the third housing 56 of the third bundle 53. It is fixed to the upstream side in the flow direction of the exhaust gas G in.

A flange joint 24 communicating with the inside is attached to the first header 22, and a flange joint 25 communicating with the inside is attached to the second header 23. The plurality of first heat transfer tubes 21 are connected in series by a plurality of U-shaped connecting tubes 26, and are arranged in a plane direction along the flow direction of the exhaust gas G. A plurality of first heat transfer tubes 21 connected in series are arranged at predetermined intervals in a direction orthogonal to the flow direction of the exhaust gas G to form a first heat transfer tube group. In the plurality of first heat transfer tubes 21, the end portion 21a is connected to the first header 22, and the end portion 21b is connected to the second header 23. A flange joint 34 communicating with the inside is attached to the first header 32, and a flange joint 35 communicating with the inside is attached to the second header 33. A plurality of second heat transfer tubes 31 connected in series by a U-shaped connecting tube 36 are arranged in a plurality of rows along the flow direction of the exhaust gas G. In the plurality of second heat transfer tubes 31, the end 31a is connected to the first header 32, and the end 31b is connected to the second header 43. A flange joint 44 communicating with the inside is attached to the first header 42, and a flange joint 45 communicating with the inside is attached to the second header 33. The plurality of third heat transfer tubes 41, which are connected in series by a U-shaped connecting tube 46, are arranged in a plurality of rows along the flow direction of the exhaust gas G. In the plurality of third heat transfer tubes 41, the end portion 41a is connected to the first header 42, and the end portion 41b is connected to the second header 43.

The end of the pipe constituting the second heat medium circulation line L12 is connected to the first header 22 via the flange joint 24. One end of the pipe constituting the first connection line L21 is connected to the second header 23 via the flange joint 25, and the other end of the pipe constituting the first connection line L21 is connected to the second header 23 via the flange joint 34. 1 It is connected to the header 32. One end of the pipe constituting the second connection line L22 is connected to the second header 33 via the flange joint 35, and the other end of the pipe constituting the second connection line L22 is connected to the second header 33 via the flange joint 44. 1 It is connected to the header 42. The end of the pipe constituting the first heat medium circulation line L11 is connected to the second header 43 via the flange joint 45.

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

The heat medium is supplied from the second heat medium circulation line L12 to the end portions 21a of the plurality of first heat transfer tubes 21 of the high temperature heating unit 11. When the heat medium flows from the end portion 21a to the end portion 21b, the high temperature heating unit 11 heats the exhaust gas G by exchanging heat with the exhaust gas G flowing through the exhaust gas passage 121c. The heat medium exchanged by the high temperature heating unit 11 is supplied from the first heat transfer tube 21 to the end portions 31a of the plurality of second heat transfer tubes 31 of the medium temperature heating unit 12 through the first connection line L21. When the heat medium flows from the end portion 31a to the end portion 31b, the medium temperature heating unit 12 heats the exhaust gas G by exchanging heat with the exhaust gas G flowing through the exhaust gas passage 121c.

The heat medium exchanged by the medium temperature heating unit 12 is supplied from the second heat transfer tube 31 to the end portions 41a of the plurality of third heat transfer tubes 41 of the low temperature heating unit 13 through the second connection line L22. When the heat medium flows from the end portion 41a to the end portion 41b, the low temperature heating unit 13 heats the exhaust gas G by exchanging heat with the exhaust gas G flowing through the exhaust gas passage 121c. After that, the heat medium exchanged by the low temperature heating unit 13 is discharged from the third heat transfer tube 41 to the first heat medium circulation line L11, and is sent to the heat recovery device 101 by the first heat medium circulation line L11.

[Structure of high temperature heating part]
5 is a schematic plan view showing the high temperature heating unit, FIG. 6 is a schematic side view showing the high temperature heating unit, and FIG. 7 is a schematic view showing the support structure of the first heat transfer tube.

As shown in FIGS. 5 to 7, the high temperature heating unit 11 is composed of the first bundle 51. In the first bundle 51, a plurality of first heat transfer tubes 21 are arranged inside the first housing 54. The first header 22 is fixed to one end of the first housing 54, and the second header 23 is fixed to the other end of the first housing 54. The plurality of first heat transfer tubes 21 arranged along the flow direction of the exhaust gas G are connected in series by the plurality of connecting pipes 26, and the plurality of first heat transfer tubes 21 connected in series are the exhaust gas G. Multiple pieces are arranged at predetermined intervals in the direction orthogonal to the flow direction.

A plurality of support plates 61 (only one is described in FIGS. 5 and 6) are arranged inside the first housing 54. The plurality of support plates 61 are arranged at predetermined intervals in the longitudinal direction of the first heat transfer tube 21, and the periphery thereof is fixed to the first housing 54. The support plate 61 is formed with a plurality of support holes 62. The plurality of support holes 62 are arranged at equal intervals in the support plate 61, and are formed, for example, in a grid pattern or a houndstooth pattern. The plurality of first heat transfer tubes 21 are inserted into and supported by the plurality of support holes 62.

The first heat transfer tube 21 has a raw tube 21c and fins 21d. The raw tube 21c has a cylindrical shape. Fins 21d are fixed to the outer peripheral surface of the raw tube 21c. The fin 21d is fixed to the raw tube 21c so as to form a spiral shape. Therefore, the first heat transfer tube 21 is configured as a fin tube. In the fin tube as the first heat transfer tube 21, the fin 21d is fixed only to the straight portion of the raw tube 21c. That is, the first heat transfer tube 21 is not provided with fins 21d at the ends 21a and 21b or the connecting tube 26.

The support hole 62 formed in the support plate 61 has an inner diameter d1 slightly larger than the outer diameter (outer diameter of the fin 21d) d2 of the first heat transfer tube 21. Further, the support plate 61 is formed to have a thickness t1 larger than the gap t2 of the fins 21d in the longitudinal direction of the first heat transfer tube 21. In this case, the difference between the inner diameter d1 and the outer diameter d2 and the difference between the thickness t1 and the gap t2 are set according to the amount of thermal expansion of the first heat transfer tube 21. Therefore, the fin tube as the first heat transfer tube 21 can be easily inserted into the support hole 62 of the support plate 61. At this time, the lower end of the fin 21d in the vertical direction of the first heat transfer tube 21 is properly placed on the inner surface of the support hole 62 in the support plate 61. Then, in the first heat transfer tube 21, a gap is secured between the upper end of the fin 21d in the vertical direction and the inner surface of the support hole 62 in the support plate 61. Therefore, even if the first heat transfer tube 21 thermally expands, the fins 21d do not come into contact with the inner surface of the support hole 62 and are not damaged.

Further, the resonance prevention plate 63 is arranged inside the first housing 54. The resonance prevention plate 63 is located between the plurality of first heat transfer tubes 21, and the periphery thereof is fixed to the first housing 54. The resonance prevention plate 63 partitions the inside of the first housing 54 in which the plurality of first heat transfer tubes 21 are arranged into two spaces. A plurality of resonance prevention plates 63 may be arranged to partition the inside of the first housing 54 into a plurality of spaces. Therefore, the resonance prevention plate 63 suppresses the resonance of the sound generated by the vibration of the plurality of first heat transfer tubes 21.

Further, the first housing 54 is provided with a plurality of support legs 64 around the first housing 54. The upper portion of the plurality of support legs 64 is fixed to the outer surface of the first housing 54, and the lower end thereof is installed on a predetermined floor surface. The support legs 64 are formed in a tubular shape. The support legs 64 are preferably cylindrical, but may be elliptical or polygonal. Since the support legs 64 are located in the exhaust gas passage, the exhaust gas G comes into contact with them to cause wear or corrosion. At this time, since the support legs 64 have a tubular shape, the contact area of the exhaust gas G is reduced, and the progress of wear or corrosion can be delayed.

Here, the configuration of the high temperature heating unit 11 has been described, but the medium temperature heating unit 12 and the low temperature heating unit 13 also have the same configuration.

[Header structure]
FIG. 8 is a cross-sectional view showing the first header, and FIG. 9 is a cross-sectional view showing the connecting structure of the first header and the first heat transfer tube.

As shown in FIG. 5, the first header 22 has a first access unit 71, and the second header 23 has a second access unit 72. The first access unit 71 is for accessing the connecting portion of the first heat transfer tube 21 inside the first header 22 from the outside of the first housing 54 and the first header 22. The second access unit 72 is for accessing the connecting portion of the first heat transfer tube 21 inside the second header 23 from the outside of the first housing 54 and the second header 23. Here, the access is an arrival route from the outside to the first heat transfer tube 21 when the operator carries out inspection, repair work, or the like of the first heat transfer tube 21.

As shown in FIGS. 5 and 8, the first header 22 has a cylindrical shape, the end portion 21a of the first heat transfer tube 21 is connected, and the inside of the first header 22 and the first heat transfer tube 21 communicate with each other. Therefore, the heat medium of the first header 22 flows to the first heat transfer tube 21. The first header 22 is formed with a first working hole 73 as a first opening constituting the first access portion 71. The first working hole 73 is provided so as to face the connecting portion to which the end portion 21a of the first heat transfer tube 21 in the first header 22 is connected. The first work hole 73 is provided with a first plug 74 detachably. The first plug 74 is attached to the first work hole 73 by a screw, fitting, or the like. During the operation of the high temperature heating unit 11, the first working hole 73 is closed with the first plug 74 attached. At the time of maintenance when the high temperature heating unit 11 is stopped, the first work hole 73 is opened by removing the first plug 74.

Similarly, the second header 23 is formed with a second working hole 75 as a second opening constituting the second access portion 72. The second working hole 75 is provided in the second header 23 so as to face the connecting portion to which the end portion 21b of the first heat transfer tube 21 is connected. A second plug 76 is detachably provided in the second work hole 75. During the operation of the high temperature heating unit 11, the second work hole 75 is closed with the second plug 76 attached. At the time of maintenance when the high temperature heating unit 11 is stopped, the second work hole 75 is opened by removing the second plug 76.

Exhaust gas G containing corrosive impurity-containing mist flows into the high-temperature heating unit 11 (reheating device 105), and the events of adhesion and evaporation occur repeatedly. Then, the first heat transfer tube 21 may be corroded and the heat medium may leak.

Therefore, for example, a leak inspection of a plurality of first heat transfer tubes 21 is performed at the time of a periodic inspection in which the operation of the high temperature heating unit 11 is stopped. When performing a leak inspection of the first heat transfer tube 21, the first access unit 71 and the second access unit 72 are used.

In the leak inspection, first, the heat medium is discharged from the plurality of first heat transfer tubes 21, the first header 22, and the second header 23. Next, the first work hole 73 and the second work hole 75 are opened by removing the first plug 74 from the first work hole 73 and the second plug 76 from the second work hole 75. In this state, a closing jig (not shown) is inserted into the first header 22 from the first working hole 73 into the first heat transfer tube 21, and the end of the first heat transfer tube 21 connected to the first header 22. The portion 21a is closed. Then, a pressurizing nozzle (not shown) is inserted into the inside of the second header 23 from the second working hole 75, and air is supplied from the end 21b of the first heat transfer tube 21 connected to the second header 23 to pressurize. Here, if the pressure in the region between the end portion 21a and the end portion 21b of the first heat transfer tube 21 can be maintained, it is determined that there is no leak in the first heat transfer tube 21. The pressure in the region between the end portion 21a and the end portion 21b in the first heat transfer tube 21 may be detected by a pressure gauge provided on a closing jig or the like.

On the other hand, if the pressure in the region between the end 21a and the end 21b of the first heat transfer tube 21 cannot be maintained, it is determined that the first heat transfer tube 21 has a leak. Such a leak inspection is performed on all the first heat transfer tubes 21.

Here, the first heat transfer tube 21 determined to have a leak is isolated and unusable. That is, the first heat transfer tube 21 determined to have a leak closes the end portions 21a and 21b. First, the stopper 77 is inserted into the first heat transfer tube 21 from the first work hole 73 into the inside of the first header 22 using a closing jig (not shown). Then, the closing jig is operated, and the stopper 77 is inserted and fixed to the end 21a of the first heat transfer tube 21 connected to the first header 22. Next, a stopper (not shown) is inserted from the second work hole 75 into the inside of the second header 23 using a closing jig (not shown). Then, the closing jig is operated, and the end portion 21b stopper of the first heat transfer tube 21 connected to the second header 23 is inserted and fixed. When the leak inspection and the plugging work in the first heat transfer tube 21 are completed, the first plug 74 is attached to the first work hole 73, and the second plug 76 is attached to the second work hole 75 to form the first work hole 73. The second working hole 75 is closed.

By fixing the stopper 77 to the respective ends 21a and 21b of the first heat transfer tube 21 determined to have a leak in this way, the heat medium cannot be used without flowing in. That is, only the first heat transfer tube 21 determined to have a leak is disabled, and only the first heat transfer tube 21 determined to have no leak can be used. Therefore, it is possible to suppress the decrease in the heat transfer area by reducing the number of the first heat transfer tubes 21 that cannot be used.

Further, as shown in FIG. 8, in the first heat transfer tube 21, the end portions 21a and 21b are connected to the first header 22 and the second header 23 by expanding the tube. That is, as shown in FIG. 9, in the first header 22, the first plug 74 is removed and the first working hole 73 is opened. A first connecting hole 81 is formed in the first header 22, and an end portion 21a of the first heat transfer tube 21 is inserted into the first connecting hole 81. In this state, the tube expansion tool 82 is inserted from the first working hole 73, and the pressurizing portion 83 is positioned inside the end portion 21a of the first heat transfer tube 21 inserted into the first connecting hole 81. Here, the pressurizing portion 83 presses the inner surface of the end portion 21a to expand the tube.

Then, as shown in FIG. 8, in the first heat transfer tube 21, the outer surface of the end portion 21a is projected outward to form the protrusion 21e. The protrusion 21e is locked by deforming the inner surface of the first connecting hole 81 in a concave shape. A plurality of protrusions 21e may be formed in the circumferential direction of the end portion 21a, or may be formed in a ring shape. In the first heat transfer tube 21, the end portion 21a of the first heat transfer tube 21 is connected to the first header 22 by engaging the protrusion 21e formed on the end portion 21a with the inner surface of the first connecting hole 81. .. After that, the inner peripheral surface of the first connecting hole 81 of the first header 22 and the end portion 21a of the first heat transfer tube 21 are hermetically welded.

Although not shown, similarly, in the first heat transfer tube 21, the first heat transfer tube 21 has a protrusion formed on the end portion 21b locked to the inner surface of the second connecting hole formed in the second header 23. The end portion 21b of is connected to the second header 23.

Although the configuration of the high temperature heating unit 11 has been described here, the medium temperature heating unit 12 and the low temperature heating unit 13 also have the same configuration.

[Action and effect of this embodiment]
The heat exchanger according to the first aspect is fixed to the housing 54 (55, 56), a plurality of heat transfer tubes 21 (31, 41) arranged inside the housing 54 (55, 56), and the housing 54. The first header 22 (32, 42) to which the end portions 21a (31a, 41a) of the plurality of heat transfer tubes 21 (31, 41) are connected, and the plurality of heat transfer tubes fixed to the housing 54 (55, 56). The second header 23 (33, 43) to which the other end 21b (31b, 41b) of the 21 (31, 41) is connected and the first header 22 (32,) from the outside of the first header 22 (32, 42). The first access portion 71 that accesses the end portions (connecting portions) 21a of the plurality of heat transfer tubes 21 (31, 41) inside the 42), and the second header 23, from the outside of the second header 23 (33, 43). A second access portion 72 for accessing the end portions (connecting portions) 21b of the plurality of heat transfer tubes 21 (31, 41) inside the 33, 43 is provided.

In the heat exchanger according to the first aspect, when performing various maintenance work on the heat transfer tube 21 (31, 41), the heat transfer tube 21 (31) is passed through the first header 22 (32, 42) from the first access unit 71. , 41) end (one end) 21a can be accessed, and the end (the other end) of the heat transfer tube 21 (31, 41) is accessible from the second access portion 72 through the second header 23 (33, 43). ) 21b can be accessed. Therefore, various maintenance work can be performed without disassembling the housing 54 (55, 56) and the like, and the workability of the maintenance work of the heat transfer tube 21 (31, 41) can be improved and the smoke can be discharged. It is possible to suppress the stoppage of smoke treatment work.

In the heat exchanger according to the second aspect, the first access unit 71 and the second access unit 72 are provided in the first header 22 (32, 42) and the second header 23 (33, 43), respectively. It has a hole (first opening) 73 and a second work hole (second opening) 75. This makes it possible to simplify the configurations of the first access unit 71 and the second access unit 72.

In the heat exchanger according to the third aspect, the first working hole 73 is provided so as to face the end portion (connecting portion) 21a of the first heat transfer tube 21 in the first header 22, and the second working hole 75 is provided. It is provided so as to face the end (connecting portion) 21b of the first heat transfer tube 21 in the second header 23. As a result, the ends 21a and 21b of the first heat transfer tube 21 can be easily accessed from the outside through the first work hole 73 and the second work hole 75.

In the heat exchanger according to the fourth aspect, the first work hole 73 and the second work hole 75 are detachably provided with the first plug 74 and the second plug 76, respectively. As a result, the high temperature heating unit 11 can be properly operated by attaching the first plug 74 and the second plug 76 to the first work hole 73 and the second work hole 75 and closing them. On the other hand, by removing and opening the first plug 74 and the second plug 76 from the first work hole 73 and the second work hole 75, maintenance work for the high temperature heating unit 11 can be easily performed.

In the heat exchanger according to the fifth aspect, the heat transfer tube 21 (31, 41) is a fin tube in which a spiral fin 21d is fixed to the outer peripheral surface of a cylindrical raw tube 21c. As a result, the heat exchange area can be increased by increasing the surface area of the heat transfer tube 21, and the heat exchange efficiency can be improved.

In the heat exchanger according to the sixth aspect, the housing 54 (55, 56) has a support plate 61 provided with a plurality of support holes 62 inside, and a plurality of heat transfer tubes 21 (31, 41). It is inserted through the support hole 62 of the above and supported. As a result, the plurality of heat transfer tubes 21 and the support plate 61 can be easily assembled, and the assembling property of the high temperature heating unit 11 can be improved.

In the heat exchanger according to the seventh aspect, the support hole 62 has an inner diameter d1 slightly larger than the outer diameter d2 of the heat transfer tube 21 (31, 41), and the support plate 61 has a thickness t1 of the heat transfer tube. It is formed larger than the gap t2 of the fins 21d in the longitudinal direction of 21 (31, 41). As a result, even if the heat transfer tube 21 thermally expands, the fins 21d do not press the inner peripheral surface of the support hole 62 and are not deformed, so that damage to the heat transfer tube 21 can be suppressed.

In the heat exchanger according to the eighth aspect, the housing 54 (55, 56) is located between the plurality of heat transfer tubes 21 (31, 41), and the resonance prevention plate 63 is arranged. As a result, the resonance of the sound generated by the vibration of the plurality of heat transfer tubes 21 can be suppressed by the resonance prevention plate 63.

In the heat exchanger according to the ninth aspect, the heat transfer tube 21 (31, 41) is inserted into the first connecting hole 81 whose end portion 21a (31a, 41a) is formed in the first header 22 (32, 42). The other end 21b (31b, 41b) is inserted into the second connecting hole formed in the second header 23 (33, 43), and the end 21a and the other end 21b are expanded to expand the first header. It is connected to 22 and the second header 23, respectively. As a result, it is possible to eliminate the need for a connection process for ensuring the strength of the first header 22 and the end portion 21a of the heat transfer tube 21 and the second header 23 and the end portion 21b of the heat transfer tube 21 by fillet welding or the like. , Workability can be improved.

In the heat exchanger according to the tenth aspect, the housing (55, 56) is provided with a plurality of support legs 64 for supporting the housing (55, 56) around the housing (55, 56), and the support legs 64 are formed in a tubular shape. .. As a result, the contact area between the exhaust gas G and the support legs 64 is reduced, and the progress of wear or corrosion can be delayed.

The smoke exhaust treatment device according to the eleventh aspect includes a heat recovery device 101 that recovers a part of the heat of the exhaust gas G, an electrostatic precipitator 102 that removes soot and dust contained in the exhaust gas G after heat recovery, and dust collection. It is provided with a scrubbering device 104 for removing sulfur oxides contained in the exhaust gas G later, and a reheating device 105 for reheating the exhaust gas G after desulfurization. As a result, in the reheating device 105, various maintenance work can be performed by the first access unit 71 and the second access unit 72 without disassembling the housing 54 (55, 56) and the like, and the heat transfer tube 21 can be performed. The workability of the maintenance work (31, 41) can be improved, and the stoppage of the smoke exhaust processing work can be suppressed.

In the above-described embodiment, the reheating device 105 includes a high temperature heating unit 11, a medium temperature heating unit 12, and a low temperature heating unit 13. In this case, the length and the number of the first heat transfer tube 21, the second heat transfer tube 31, and the third heat transfer tube 41 may be appropriately set according to the usage mode.

Further, in the above-described embodiment, the reheating device 105 includes the first bundle 51 and the second bundle 52, the third bundle 53, the high temperature heating unit 11 constitutes the first bundle 51, and the medium temperature heating unit 12 constitutes the second bundle. The bundle 52 is configured, and the third bundle 53 is configured by the low temperature heating unit 13, but the configuration is not limited to this. For example, the medium temperature heating unit 12 and the low temperature heating unit 13 may be configured by a shared bundle.

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

11 High temperature heating part 12 Medium temperature heating part 13 Low temperature heating part 21 1st heat transfer tube 21a, 21b End 21c Element tube 21d Fin 21e Projection 22 1st header 23 2nd header 24, 25 Flange joint 26 Connecting tube 31 2nd transmission Heat tubes 31a, 31b Ends 32 1st header 33 2nd header 34,35 Flange joints 36 Connecting pipes 41 3rd heat transfer tubes 41a, 41b Ends 42 1st header 43 2nd headers 44, 45 Flange joints 46 Connecting pipes 51 1 bundle 52 2nd bundle 53 3rd bundle 54 1st housing 55 2nd housing 56 3rd housing 61 Support plate 62 Support hole 63 Resonance prevention plate 64 Support leg 71 1st access part 72 2nd access part 73 1st work hole (1st opening)
74 1st plug 75 2nd work hole (2nd opening)
76 2nd plug 77 Stopper 81 1st connecting hole 82 Pipe expansion tool 83 Pressurizing part 100 Smoke exhaust treatment device 101, 101a, 101b Heat recovery device 102, 102a, 102b Electrodust collector 103, 103a, 103b Blower 104 Scrubber 105 Reheating device 106, 106a, 106b 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 1st heat medium circulation line L12 2nd heat medium circulation line L13 Steam line L14 Steam drain line L21 1st connection line L22 2nd connection line G Exhaust gas

Claims (11)

With the housing
A plurality of heat transfer tubes arranged inside the housing,
A first header fixed to the housing and connected to one end of the plurality of heat transfer tubes,
A second header fixed to the housing and connected to the other ends of the plurality of heat transfer tubes.
A first access unit that accesses the connecting portion of the plurality of heat transfer tubes inside the first header from the outside of the first header, and a first access unit.
A second access portion that accesses the connecting portion of the plurality of heat transfer tubes inside the second header from the outside of the second header, and a second access portion.
A heat exchanger equipped with. The first access unit and the second access unit have a first opening and a second opening provided in the first header and the second header, respectively.
The heat exchanger according to claim 1. The first opening is provided facing the connecting portion of the heat transfer tube in the first header, and the second opening is provided facing the connecting portion of the heat transfer tube in the second header.
The heat exchanger according to claim 2. A first plug and a second plug are detachably provided in the first opening and the second opening, respectively.
The heat exchanger according to claim 2 or 3. The heat transfer tube is a fin tube in which spiral-shaped fins are fixed to the outer peripheral surface of a cylindrical raw tube.
The heat exchanger according to any one of claims 1 to 4. In the housing, a support plate provided with a plurality of support holes is arranged therein, and the plurality of heat transfer tubes are inserted through the plurality of the support holes and supported.
The heat exchanger according to claim 5. The support hole has an inner diameter slightly larger than the outer diameter of the heat transfer tube, and the support plate has a thickness larger than the gap between the fins in the longitudinal direction of the heat transfer tube.
The heat exchanger according to claim 6. The housing is located between the plurality of heat transfer tubes, and a resonance prevention plate is arranged.
The heat exchanger according to any one of claims 1 to 7. One end of the heat transfer tube is inserted into the first connecting hole formed in the first header, the other end is inserted into the second connecting hole formed in the second header, and the one end and the other By expanding the end portion, it is connected to the first header and the second header, respectively.
The heat exchanger according to any one of claims 1 to 8. The housing is provided with a plurality of support legs for supporting the housing around the housing, and the support legs are formed in a tubular shape.
The heat exchanger according to any one of claims 1 to 9. A heat recovery device that recovers part 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 that removes sulfur oxides contained in the exhaust gas after dust collection,
A reheater to which the heat exchanger according to any one of claims 1 to 10 is applied to reheat the exhaust gas after desulfurization, and a reheater.
A flue gas treatment device equipped with.

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