JP2020026939A - Heat exchanger - Google Patents

Abstract

To restrain corrosion in heat transfer pipes in heat exchangers while restraining an increase in cost.SOLUTION: Heat exchangers (4 and 8) comprise: wall parts (44, 35, and 49) separating an interior in which fluid flows, and an exterior; corrosion-resistant coatings (61) applied to outer surfaces of heat transfer pipes (11 and 12); protective members (62) housing interior side end parts (61a) of the corrosion-resistant coatings (61) in the interior, and protecting end parts of the heat transfer pipes (11 and 12); and surrounding members (63) surrounding the outer surfaces of the heat transfer pipes (11 and 12) between the interior side end parts (61a) of the corrosion-resistant coatings (61) and the wall parts (44, 35, and 49), and having corrosion resistance.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a heat exchanger installed in a fluid and performing heat exchange with the fluid, and more particularly to a heat exchanger used in exhaust gas discharged from combustion equipment such as a boiler.

  BACKGROUND ART In a boiler or the like in a thermal power plant, there is known a heat exchanger that performs heat exchange with discharged exhaust gas, that is, a so-called GGH (gas gas heater). Note that GGH is used both when heat is applied to the exhaust gas to increase the temperature of the exhaust gas, and when heat is absorbed from the exhaust gas to lower the temperature of the exhaust gas. In addition, there is a rotary regeneration type heat exchanger utilizing heat storage, such as a Jungstrom type, in the GGH, but it is not included in the present invention, and a heat transfer tube (tube) is provided at each point where heat recovery from exhaust gas and reheating are performed. Is installed, and the heat medium circulates through the tube and exchanges heat.

FIG. 8 is an explanatory diagram of a conventional heat exchanger.
In FIG. 8, in a conventional heat exchanger 01, a tube 03 is disposed so as to penetrate a casing 02. A header 04 is connected to one end of the tube 03 outside the casing 02. Therefore, the heat medium is supplied from the header 04 to the tube 03, and heat exchange with the exhaust gas is performed in the exhaust gas flow path (space) 06 inside the casing 02.

In FIG. 8, the exhaust gas flowing in the flow path 06 of a boiler or the like contains halides (Cl, Br, etc.), nitrogen oxides (NOx) and sulfur oxides (SOx), combustion ash, and the like. Therefore, the tube 03 may be corroded by these factors. In particular, the tube 03 may be washed with water during cleaning. If water adheres to the tube 03 to which nitrogen oxide or the like has adhered, nitric acid or the like is easily generated, and there is also a problem that corrosion is likely to proceed.
Therefore, the outer surface of the tube 03 is generally provided with a corrosion-resistant film (coating) 03a. At this time, it is not necessary to apply the coating 03a to the outside of the casing 02 where there is no possibility of corrosion. Therefore, it is only necessary to apply the coating 03a to the inside of the casing 02, and if the coating 03a is applied to the outside with a margin, the expensive corrosion-resistant coating material is wasted and the cost is increased.

  On the other hand, when the coating 03a is applied to the tube 03 in accordance with the inner surface of the casing 02, a part without the coating 03a may be generated inside the casing 02 due to a manufacturing error or an assembly error of each part. In this case, there is a problem that corrosion proceeds from a portion where the coating 03a is not applied. It is to be noted that there is a problem in that an attempt to reduce a manufacturing error or the like increases manufacturing cost and assembly cost, and it is impossible as a practical problem to completely eliminate the error.

  An object of the present invention is to suppress corrosion while suppressing increase in cost in a heat transfer tube in a heat exchanger.

  The invention according to claim 1 that solves the technical problem is a heat transfer tube that is disposed in a fluid and through which a heat medium can flow, a wall part that separates the inside and the outside where the fluid flows, A corrosion-resistant coating applied to the outer surface and applied to the vicinity of the inner side of the wall, and an inner end of the corrosion-resistant coating disposed on the inner side of the wall, A protective member that accommodates and protects the end of the heat transfer tube, and a surrounding member that surrounds the outer surface of the heat transfer tube between the inner end of the corrosion-resistant coating and the wall portion, And a surrounding member having a property.

  The invention according to claim 2 is the heat exchanger according to claim 1, characterized in that the heat transfer tube is provided with the surrounding member detachably sandwiched from outside.

  The invention according to claim 3 is the heat exchanger according to claim 1 or 2, wherein the surrounding member is provided so as to fill a gap between the protection member and the heat transfer tube. .

  The invention according to claim 4, wherein the header is arranged outside the wall portion, an end of the heat transfer tube is connected, and a heat medium can flow through the inside, the heat transfer tube, the wall portion, The heat exchanger according to any one of claims 1 to 3, wherein bundles having the protective member and the bundle are stacked in the direction of gravity.

  The invention according to claim 5 is characterized in that, in a plurality of bundles stacked in the direction of gravity, the surrounding member is installed only in the bundle arranged below the direction of gravity. A heat exchanger as described.

  According to the first aspect of the present invention, the end portion of the heat transfer tube is protected by the protection member, and the end portion of the heat transfer tube is surrounded by the corrosion-resistant enclosure member. It is possible to suppress the corrosion of the heat transfer tube while suppressing the cost of improving the heat transfer.

  According to the second aspect of the present invention, in addition to the effect of the first aspect of the present invention, the surrounding member is configured to be detachable from the heat transfer tube. It can be easily removed, replaced, and cleaned. Further, the surrounding member can be easily added to the existing heat exchanger having no surrounding member.

  According to the third aspect of the present invention, in addition to the effect of the first or second aspect of the present invention, by filling the gap between the protective member and the heat transfer tube with the surrounding member, compared with the case where the gap is open. Thus, corrosion of the heat transfer tube disposed inside the protection member can be further suppressed.

  According to the invention described in claim 4, in addition to the effect of the invention described in any of claims 1 to 3, the size and scale of the heat exchanger can be easily changed by increasing or decreasing the number of bundles. It is possible.

  According to the invention described in claim 5, in addition to the effect of the invention described in claim 4, by installing the surrounding member in the lower bundle in the direction of gravity, the lower side where ash in the fluid is liable to be deposited is provided. Of the heat transfer tube can be suppressed. In addition, since the surrounding member is not provided in the upper bundle in which corrosion does not easily proceed, the overall manufacturing cost can be reduced.

It is an explanatory view of a flue gas treatment system including a heat exchanger of the present invention. It is an explanatory view of the heat exchanger of Example 1 of the present invention. FIG. 3 is an exploded view of the heat exchanger of FIG. 2. FIG. 4 is an explanatory diagram of a bundle of the heat exchanger according to the first embodiment. FIG. 3 is an explanatory view of a main part on the header side of the heat transfer tube of the first embodiment. FIG. 4 is an explanatory diagram of a surrounding member according to the first embodiment. FIG. 7A is a diagram corresponding to FIG. 5, FIG. 7B is a diagram corresponding to FIG. 6, and FIG. 7C is a diagram in which a slit is formed in a sleeve. FIG. It is explanatory drawing of the conventional heat exchanger.

  Hereinafter, embodiments of the present invention will be described.

FIG. 1 is an explanatory diagram of a flue gas treatment system including the heat exchanger of the present invention.
In FIG. 1, in the flue gas treatment system (plant) S to which the heat exchanger of the first embodiment is applied, after the exhaust gas from the boiler 1 is introduced into the denitration device 2 and the nitrogen oxides in the exhaust gas are removed, In the air preheater (A / H) 3, heat is exchanged with combustion air to the boiler 1. Next, the exhaust gas is introduced into a GGH heat recovery device 4 as an example of a heat exchanger, and heat exchange (heat recovery) is performed. Exhaust gas whose gas temperature has decreased after passing through the GGH heat recovery device 4 is introduced into a dust collector (EP: Electrostatic Precipitator) 5 in a state where the electric resistance value of dust in the gas has decreased, and most of the dust in the exhaust gas Is removed. Thereafter, the exhaust gas is pressurized by a fan 6 and introduced into a wet flue gas desulfurization device (FGD) 7 to remove a part of sulfur oxides and dust in the exhaust gas by gas-liquid contact. In the wet flue gas desulfurization device 7, the exhaust gas cooled to the saturated gas temperature is heated by the GGH reheater 8 as an example of the gas gas heat exchanger using the heat recovered by the GGH heat recovery device 4 ( Heat exchange, reheating). The exhaust gas that has passed through the GGH reheater 8 is discharged from the chimney 9.

FIG. 2 is an explanatory diagram of the heat exchanger according to the first embodiment of the present invention.
FIG. 3 is an exploded view of the heat exchanger of FIG.
2 and 3, the GGH heat recovery device 4 has a housing 31 as an example of a housing. The housing 31 includes a plate-shaped bottom plate 32 as an example of a lower cover, a plate-shaped back plate 33 as an example of a back cover, and a plate-shaped top plate 34 as an example of an upper cover. An inter-bundle cover 35 extending in the vertical direction is supported at the front of the housing 31. The inter-bundle covers 35 extend in the up-down direction (gravity direction), and are arranged at predetermined intervals in the left-right direction (direction in which exhaust gas (smoke exhaust) flows). A plurality of heat exchange bundles 41 are housed inside the housing 31.

FIG. 4 is an explanatory diagram of the bundle of the heat exchanger according to the first embodiment.
3 and 4, each heat exchange bundle 41 has a first header 42 as an example of a first attachment portion, and a second header 43 as an example of a second attachment portion. The first header 42 and the second header 43 of the first embodiment are formed in columns extending in the vertical direction. Each of the headers 42 and 43 is formed in a shape in which the inside is hollow and the upper end and the lower end are closed, and a flowable space is formed inside. Each of the headers 42 and 43 supports a mounting plate 44 that extends in the left-right direction.

The rear surface of each of the headers 42 and 43 supports a heat transfer tube 11 extending rearward. The heat transfer tube 11 is configured to bend at the rear end or the front end inside the housing 31 and to reciprocate a plurality of times in the front-rear direction. The headers 42 and 43 support a plurality of heat transfer tubes 11 at intervals in the vertical direction. Both ends of each of the heat transfer tubes 11 are supported by headers 42 and 43, and the heat medium can enter and exit the heat transfer tubes 11 from the headers 42 and 43.
Each heat transfer tube 11 is supported by a support member 47 at the center in the front-rear direction. The support member 47 is formed in a shape in which a plurality of holes through which the heat transfer tubes 11 pass are formed in the plate. Therefore, the heat transfer tube 11 is not supported in a cantilever state only by the headers 42 and 43, but is held by the headers 42 and 43 and the support member 47. Although one support member 47 is shown in the front-rear direction and the left-right direction, a plurality of support members 47 may be provided in the front-rear direction or a plurality of support members 47 in the left-right direction depending on the length of the heat transfer tube 11. It is possible.

  Each of the headers 42 and 43 has a plug hole 48 at a position corresponding to the heat transfer tube 11. The plug hole 48 is a hole that penetrates in the front-rear direction, and has a rear end connected to an inlet or an outlet of the heat transfer tube 11. The front end of the plug hole 48 is closed with a stopper (not shown) during normal use. If any one of the heat transfer tubes 11 breaks down and the heat medium leaks out, the plug of the plug hole 48 is removed, and the inlet or the outlet of the heat transfer tube 11 is closed with a stopper plug (not shown) through the plug hole 48 so that the heat medium is not leaked. It is possible to stop the leak.

A casing plate 49 as an example of a connection member is detachably supported between the headers 42 and 43. The casing plate 49 has a height corresponding to the height of the headers 42 and 43 in the vertical direction. The casing plate 49 is detachably supported on the mounting plate 44 by bolts (not shown). The method of detachably fixing the casing plate 49 to the mounting plate 44 is not limited to the bolt. For example, instead of bolting, any detachable fixing method, such as fillet welding of the casing plate 49 and the headers 42 and 43 and detachment by gouging or the like, can be adopted.
Therefore, when the casing plate 49 is mounted, the headers 42 and 43 are connected. Therefore, when the casing plate 49 is mounted, the headers 42 and 43 and the heat transfer tube 11 are integrated with high rigidity, and leakage of exhaust gas from between the headers 42 and 43 is also suppressed.

The members denoted by the reference numerals 42 to 49 constitute the heat exchange bundle 41 of the first embodiment. The heat exchange bundle 41 is configured to be housed in the housing 31 as one unit. When the heat exchange bundle 41 is housed in the housing 31, the heat exchange bundle 41 is surrounded by a bottom plate 32, a back plate 33, a top plate 34, an inter-bundle cover 35, headers 42 and 43, and a casing plate 49 as an example of a wall. An exhaust gas path 50 as an example of a fluid flow path is formed inside. The heat transfer tube 11 is arranged in the exhaust gas passage 50, and is configured to be able to exchange heat with the exhaust gas flowing through the exhaust gas passage 50.
The GGH reheater 8 is also configured for the heat transfer tube 12 in the same manner as the GGH heat recovery device 4.

  3 and 4, in the GGH heat recovery unit 4 and the GGH reheater 8 according to the first embodiment, three rows are arranged in the upstream, middle, and downstream directions with respect to the flow direction of the exhaust gas. In each of the downstream rows, three stages of heat exchange bundles 41 are vertically stacked. Therefore, the GGH heat recovery unit 4 of the first embodiment includes nine heat exchange bundles 41 of the upstream lower bundle 101 to the upper upstream bundle 103, the middle lower bundle 104 to the middle upper bundle 106, and the lower downstream bundle 107 to the downstream upper bundle 109. Have. Similarly, the GGH reheater 8 has nine heat exchange bundles 41 of an upstream lower bundle 111 to an upstream upper bundle 113, a middle lower bundle 114 to a middle upper bundle 116, and a downstream lower bundle 117 to a downstream upper bundle 119.

In the middle bundles 102, 105, 108, 112, 115, and 118, the lower ends of the headers 42 and 43 are directly stacked on the upper ends of the lower bundles 101, 104, 107, 111, 114, and 117, and are fixed with bolts. ing. Similarly, the lower ends of the headers 42 and 43 of the upper bundles 103, 106, 109, 113, 116 and 119 are directly stacked on the upper ends of the middle bundles 102, 105, 108, 112, 115 and 118, and are fixed by bolts. Have been. Note that the configuration is not limited to the configuration in which the upper headers 42, 43 are directly stacked on the lower headers 42, 43, and a configuration in which the headers 42, 43 are stacked via a spacer, a plate, a frame, or the like is also possible.
In FIG. 2, each heat exchange bundle 41 is connected externally by a connection pipe (not shown), and the heat medium is configured to be movable.

(Description of baffle box and sleeve)
FIG. 5 is an explanatory view of a main part on the header side of the heat transfer tube according to the first embodiment.
In FIG. 5, in each of the heat exchange bundles 41 of the first embodiment, the heat transfer tubes 11 and 12 connected to the headers 42 and 43 have a corrosion-resistant coating 61 formed thereon. 43 is provided up to the vicinity of the end. As the film 61, any material can be used as long as it is a material having corrosion resistance. For example, enamel coating or glass flare lining can be used.
A baffle box 62 as an example of a protection member is arranged inside the headers 42 and 43 (in the exhaust gas passage 50). The baffle box 62 is formed in a box shape. The size of the baffle box 62 is set so that the end 61 a of the coating 61 of the heat transfer tubes 11 and 12 is housed inside the baffle box 62. In the first embodiment, the inner wall 62a of the baffle box 62 is formed outside the outermost fins 11a of the heat transfer tubes 11, 12.

  The baffle box 62 has a through hole 62b through which the heat transfer tubes 11 and 12 pass. Note that a gap is formed between the through hole 62b and the heat transfer tubes 11 and 12. Here, the heat transfer tubes 11 and 12 and the baffle box 62 thermally expand or contract as the temperature of the exhaust gas rises and falls. The heat transfer tubes 11 and 12 in which the heat medium flows therein and the baffle box 62 in which the heat medium does not flow may have different temperatures, and a difference may occur in thermal expansion / contraction. Therefore, unless a gap is formed between the baffle box 62 and the heat transfer tubes 11 and 12, the heat transfer tubes 11 and 12 may be damaged at the time of thermal expansion / shrinkage and the heat medium may leak. Therefore, in the first embodiment, the gap is set and formed between the through-hole 62b of the baffle box 62 and the heat transfer tubes 11 and 12 such that a gap that does not break during thermal deformation is formed.

FIG. 6 is an explanatory diagram of the surrounding member according to the first embodiment.
In FIG. 5, a sleeve 63 as an example of a surrounding member is disposed inside the baffle box 62. The sleeve 63 is formed so as to at least surround the outer circumference of the heat transfer tubes 11 and 12 from the end of the coating 61 to the headers 42 and 43. In FIG. 6, the sleeve 63 of the first embodiment is formed so as to surround a part of the headers 42 and 43 in addition to the outer surfaces of the heat transfer tubes 11 and 12.
For the sleeve 63 of the first embodiment, any material can be used as long as it is a corrosion-resistant material, and a corrosion-resistant metal or resin can be used.
In FIG. 5, the heat transfer tubes of the heat exchanger use the heat transfer tubes 11 and 12 with fins, but may be heat transfer tubes without fins (bare tubes).
The finned heat transfer tubes 11 and 12 can improve the heat transfer performance in exhaust gas having no ash, but in the exhaust gas having a large amount of ash, ash easily accumulates on the fold-shaped fin portion, and the heat transfer performance is reduced. . On the other hand, a heat transfer tube without fins can prevent a decrease in heat transfer performance due to ash accumulation, so that a heat transfer tube with fins or a heat transfer tube without fins can be selected according to the ash content in the exhaust gas.

6, the sleeve 63 of the first embodiment is formed of two symmetric members so that the heat transfer tubes 11 and 12 can be sandwiched from both sides in the radial direction. That is, the sleeve 63 of the first embodiment has a so-called split structure. Therefore, the sleeve 63 can be attached later with the heat transfer tubes 11 and 12 attached to the headers 42 and 43. Although not shown, the baffle box 62 also has a two-piece configuration like the sleeve 63, so that the heat transfer tubes 11, 12 can be sandwiched and installed from both sides in the radial direction. . Therefore, the baffle box 62 and the sleeve 63 can be additionally attached to an existing heat exchanger not provided with a baffle box or the like later, or can be detached during maintenance.
In addition, the baffle box 62 and the sleeve 63 are illustrated as being divided into two parts, but are not limited thereto. It is also possible to configure with three or more members. In addition, it is also possible to form a slit (cut) in a tubular or weight-shaped member, and to widen the slit at the time of attachment / detachment for attachment / detachment.

(Operation of First Embodiment)
In the heat exchangers 4 and 8 of the first embodiment having the above-described configuration, when the exhaust gas flows through the exhaust gas path 50, the components (corrosion of nitrogen oxides, sulfur oxides, halogenated oxides) Even if hydrogen or the like is contained, the corrosion is prevented by the corrosion-resistant coating 61 on the outside of the baffle box 62.
Further, the ends of the heat transfer tubes 11 and 12 are surrounded by the baffle box 62, so that ash and the like are prevented from adhering to the ends of the heat transfer tubes 11 and 12. Further, in the first embodiment, the sleeves 63 are arranged at the ends of the heat transfer tubes 11 and 12, so that ash or the like is prevented from adhering to portions where the coating 61 is not formed.

  Therefore, in the first embodiment, there is no need to precisely coat the coating 61 to the very end of the heat transfer tubes 11 and 12 or to make the manufacturing errors and assembly errors of the heat transfer tubes 11 and 12 and the headers 42 and 43 high. The portion without the coating 61 between the end 61 a of the coating 61 and the headers 42 and 43 can be protected by the baffle box 62 and the sleeve 63. Therefore, it is possible to suppress the corrosion of the heat transfer tubes 11 and 12 while suppressing an increase in cost, as compared with a case where precise coating or error accuracy is increased.

  Further, the baffle box 62 and the sleeve 63 of the first embodiment are configured to be easily detachable from the heat transfer tubes 11 and 12. Therefore, maintenance work becomes easy. Furthermore, it is possible to easily add an existing heat exchanger without the sleeve 63 or the like.

  Further, in the heat exchangers 4 and 8 of the first embodiment, the heat exchange bundles 41 are vertically stacked. All the heat exchange bundles 41 are provided with a baffle box 62 and a sleeve 63. Here, when the exhaust gas path 50 is set in the horizontal direction, ash easily accumulates on the lower heat exchange bundle 41 in the direction of gravity, and the adverse effect of the ash increases. Therefore, the baffle box 62 and the sleeve 63 may be provided only in the lower bundles 101, 104, 107, 111, 114, and 117 in the gravity direction, or may be provided in accordance with the amount of ash contained in the exhaust gas. , 104, 107, 111, 114, 117 and the middle bundles 102, 105, 108, 112, 115, 118 are provided with a sleeve 63, and the upper bundles 103, 106, 109, 113, 116, 119 are provided with a sleeve 63, etc. May be omitted.

(Modification 1)
7A and 7B are explanatory views of Modification Example 1 of the present invention. FIG. 7A is a view corresponding to FIG. 5, FIG. 7B is a view corresponding to FIG. 6, and FIG. FIG. 9 is an explanatory diagram in a case where is formed.
In the heat exchangers 4 and 8 according to the first embodiment, the configuration in which the mounting plates 44 are supported by the headers 42 and 43 is illustrated, but the configuration is not limited thereto. As shown in FIG. 7, the headers 42 and 43 may be arranged outside the heat exchanger casing 44 'as an example of the wall, and the baffle box 62 may be arranged inside the casing 44'. It is possible. Then, inside the baffle box 62, a sleeve 63 'may be provided so as to surround the ends of the heat transfer tubes 11 and 12 (the end on the casing 44' side including the end 61a of the coating 61).

At this time, arranging the sleeve 63 'so as to fill the through-hole 62b makes it more difficult for ash and the like to enter the baffle box 62, and the effect of suppressing corrosion is likely to be enhanced. The sleeve 63 ′ is made of an elastic resin, so that the sleeve 63 ′ can absorb the difference between the heat transfer tubes 11 and 12 and the baffle box 62 during thermal deformation.
The sleeve 63 'of the first modification can be divided into two as in the first embodiment as shown in FIG. 7B, or can be divided into two as shown in FIG. As described in 1, the configuration in which the slit 63a is formed is also possible.
The configuration shown in FIG. 7 has the same operation and effect as the first embodiment.
Also in the configuration shown in FIG. 7, similarly to the configuration in FIG. 5, a heat transfer tube with fins or a heat transfer tube without fins can be selected according to the ash content in the exhaust gas.

(Other changes)
As described above, the embodiments of the present invention have been described in detail. However, the present invention is not limited to the above embodiments, and various changes may be made within the scope of the present invention described in the appended claims. Is possible. Modifications (H01) to (H03) of the present invention are exemplified below.
(H01) In the above embodiment, the specific material names, numerical values, and specific shapes exemplified can be appropriately changed according to design, specifications, and the like.
(H02) In the above embodiment, the configuration in which a plurality of heat exchange bundles 41 are stacked, or the heat exchange bundles 41 are arranged in the upstream, middle, and downstream directions is exemplified, but the present invention is not limited to this. The number of bundles can be increased or decreased according to the required heat exchange efficiency or the like. Further, the present invention is not limited to the configuration in which the unit-shaped heat exchange bundles 41 can be increased or decreased by stacking or arranging them, and a conventionally known heat exchange in which a large number of heat transfer tubes are arranged inside a plate-shaped casing (housing, frame). It is also applicable to vessels.
(H03) In the first modification, it is preferable that the through hole 62b is filled with the sleeve 63 '. However, as in the first embodiment, a structure in which the gap of the through hole 62b is not filled may be used. Further, in the first embodiment, similarly to the first modification, the gap between the through holes 62b can be filled with the sleeve 63.

4, 8 ... heat exchanger,
11, 12 ... heat transfer tubes,
11a, 12a ... fins,
35,44,49,44 '... wall,
41 ... Bundle,
42, 43 ... header,
61 ... Corrosion-resistant coating,
61a ... the inner end of the corrosion resistant coating,
62 ... Protective member,
63, 63 '... enclosing member.

Claims (5)

A heat transfer tube arranged in a fluid and through which a heat medium can flow,
A wall that separates the inside and outside of the fluid flow,
A corrosion-resistant coating applied to the outer surface of the heat transfer tube, and applied to near the inner side of the wall;
A protection member that is disposed on the inner side of the wall portion and accommodates the inner end of the corrosion-resistant coating therein to protect the end of the heat transfer tube;
A surrounding member surrounding the outer surface of the heat transfer tube between the inner end of the corrosion-resistant coating and the wall portion, wherein the surrounding member has corrosion resistance;
A heat exchanger comprising: The surrounding member that can be detached by sandwiching the heat transfer tube from the outside,
The heat exchanger according to claim 1, further comprising: The surrounding member arranged to fill a gap between the protection member and the heat transfer tube,
The heat exchanger according to claim 1 or 2, further comprising:   A bundle having a header disposed outside the wall portion, connected to an end of the heat transfer tube, and through which a heat medium can flow, the heat transfer tube, the wall portion, and the protection member is provided. 4. The heat exchanger according to claim 1, wherein the heat exchangers are stacked in the direction of gravity.   The heat exchanger according to claim 4, wherein the enclosing member is installed only in the bundle arranged below the gravity direction among the plurality of bundles stacked in the gravity direction.

Images