JP2003227696A - Heat exchanger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat exchanger wherein corrosion resistance against acid condensed water produced from an external fluid is improved. <P>SOLUTION: This heat exchanger includes a tube 110 for forming a fluid passage 110a inside, and exchanges heat between an internal fluid flowing in the fluid passage 110a, and the external fluid flowing in an outer side of the tube 110 and producing the acid condensed water by condensing in exchanging heat. The tube 110 includes a junction 113 formed by brazing and joining a first plate shaped member 111 and a second plate shaped member 112 for forming air-tightness between an inner part side for forming the fluid passage 110a and an outer part side where the external fluid flows. The junction 113 is formed so as to have a lower side longer than an upper side in the tube 110. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a heat exchanger for exchanging heat between a fluid and a combustion gas, and is particularly suitable for use as a heat exchanger for a water heater.

[0002]

As a conventional technique, for example, Japanese Patent Laid-Open No. 9-1
There is a heat exchange device described in Japanese Patent No. 26554. This heat exchange device includes a main heat exchanger that recovers sensible heat of combustion gas to heat hot water, and a sub heat exchanger that is arranged downstream of the main heat exchanger in the flow direction of combustion gas. The sub heat exchanger also recovers the latent heat of condensation of the combustion gas to heat the hot water before being heated by the main heat exchanger.

[0003]

However, in the above sub heat exchanger, the temperature of the combustion gas is the dew point temperature (50 to 6).
Nitrogen oxide (NO) in combustion gas
x) and sulfide oxide (SOx) dissolved acidic condensed water is generated. For this reason, when a so-called drone cup type heat exchanger capable of ensuring a large heat transfer area is used as the auxiliary heat exchanger, there arises a problem that the joint portion of the tube through which the hot water supplies flows corrodes. That is, the tube used for the Delon cup type heat exchanger is usually formed by combining two heat transfer plates (tube plates) in the plate thickness direction and brazing the peripheral portions of both. Where Cu
When a brazing material of the system is used, the generated condensate water corrodes the brazing material, and it becomes impossible to secure sufficient joint strength (durability).

To solve this problem, for example, Japanese Patent Laid-Open No. 9-2
As described in Japanese Patent No. 85888, it is known that brazing may be performed with a Ni-based brazing material. However, according to WHO (World Health Organization) guidelines for drinking water quality, Cu is 0.5 mg / L, whereas Ni is 0.02 mg / L, which is severe, so there is a possibility of direct exposure to hot water. It is not desirable to use Ni-based brazing material at the joints of certain tubes.

The present invention has been made under the above circumstances, and an object thereof is to provide a heat exchanger capable of improving the corrosion resistance to acidic condensed water produced from an external fluid.

[0006]

The present invention employs the following technical means in order to achieve the above object.

According to the first aspect of the invention, the tube (110) forming the fluid passage (110a) is provided inside,
The internal fluid flowing through the fluid passage (110a) and the tube (1
A heat exchanger that exchanges heat with an external fluid that flows outside of 10) and condenses at the time of heat exchange to generate acidic condensed water, wherein the tube (110) includes a first plate member (111). )
And the second plate member (112) are brazed and joined together,
A joint part (113) for partitioning airtightness between the inner side where the fluid passage (110a) is formed and the outer side where the external fluid flows.
The joint portion (113) is characterized in that the lower side of the tube (110) is formed longer than the upper side thereof.

As a result, even if the generated acid condensed water drops down and adheres to the lower joint (113) and corrosion of the brazing material occurs, the joint (113) is formed long, The time required for the corrosion to reach the inner side of the tube (110) can be increased, and the corrosion resistance can be improved.

According to the second aspect of the present invention, in the heat exchanger according to the first aspect, the external fluid is combustion gas, and the external fluid is made to flow downward from above the outside of the tube (110). Is characterized by.

As a result, the flow of the combustion gas coincides with the direction in which the acidic condensed water drops, so that the ventilation resistance of the combustion gas can be reduced and the heat exchange efficiency can be improved.

According to the third aspect of the invention, the joint portion (11
3) is characterized in that the passage portion (100a) is formed longer than the non-passage portion (100b) of the external fluid in the tube (110).

In the passage (100a) of the combustion gas passing through the tube (110), acidic condensed water is generated and adheres. Further, even if the acid condensed water adheres to the joint portion (113) and the brazing filler metal is corroded, since the joint portion (113) of the combustion gas passage portion (100a) is formed long, the corrosive corrosion occurs in the tube (110). ), The time required to reach the inside can be earned, and the corrosion resistance can be improved.

According to the invention described in claim 4, claims 1 to 3
In any one of the heat exchangers described in 1., the end portion (114) of the joint portion (113) on the longer side has a first plate member (111) and a second plate member (112). It is characterized in that at least one is formed so as to open to the external fluid side.

As a result, the acidic condensed water is transferred to the joint (11
Since it can be made difficult to adhere to the brazing material of 3), the corrosion resistance can be further improved.

In the invention described in claim 5, claims 1 to 3 are provided.
In any one of the heat exchangers described in 1., the first plate-shaped member (111) and the second plate-shaped member (112) are integrally formed by a connecting portion (115) to which they are connected, and are long. The end (1) of the joint (113) on the side to be formed
14) is characterized in that the connection portion (115) is formed by bending.

As a result, the acidic condensed water is absorbed in the joint (11
Since it can be prevented from directly adhering to the brazing material of 3), the corrosion resistance can be further improved.

The reference numerals in parentheses of the above-mentioned means indicate the correspondence with the concrete means described in the embodiments to be described later.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A first embodiment of the present invention will be described with reference to the drawings shown in FIGS. FIG. 1 is a sectional view showing a main part of the present invention (a sectional view taken along the line AA in FIG. 2), FIG. 2 is a front view of a heat exchanger 100, FIG. 3 is a plan view of the heat exchanger 100, and FIG. Tube plate 111
FIG.

The heat exchanger 100 of the present invention is used in a water heater to exchange heat between hot water (internal fluid) and combustion gas (external fluid), and as shown in FIGS. 2 and 3. , A plurality of tubes 110 are outer fins (hereinafter, fins)
The heat exchanger 100 is a so-called drone cup type that is formed by stacking together with 130. In addition, each member (described below) constituting the heat exchanger 100 is
All are made of stainless steel and are manufactured by integral brazing after the entire shape is assembled.

The tube 110 includes a tube plate 112 (second plate-shaped member, not shown) similar to the tube plate (first plate-shaped member) 111 shown in FIG. It is formed by doing. The overall shape is a U-shaped running water passage (fluid passage) 11 inside.
A flat pipe portion 110b forming 0a and a set of tank portions 110c communicating with both ends of the flowing water passage are provided, and a communication port 111a is opened in the tank portion 110c.

The tube plate 112 is provided with a plurality of claws 112a on the outer periphery of the tube plate 111. After the tube plates 111 and 112 are combined, the claws 112a are caulked to form the tube 110. It keeps its shape.

The tank portion 110c is provided with a larger thickness width than the flat tube portion 110b, and the outer surfaces of the tube plates 111 and 112 forming the tank portion 110c are
A flat portion 111d is annularly provided around the communication port 111a.

As shown in FIG. 3, the plurality of tubes 110 are formed by stacking the tank portions 110c of each other in series, and joining the flat portions 111d provided around the communication port 111a. As a result, the running water passage 1 of each tube 110 is passed through the communication port 111a opening to the tank portion 110c.
10a communicate with each other. In addition, as shown in FIG. 1, inner fins 120 may be inserted inside the tube 110 in order to increase the heating area.

The fins 130 are formed by bending a thin plate material in an uneven shape, and are arranged so that the combustion gas flows from the upper side to the lower side in the uneven space, and the tube plates 111 and 112 forming the flat tube portion 110b. On the surface of Ni
It is joined using a brazing material of the system.

The tube 11 arranged on one end side in the stacking direction
2, a hot water supply port 140 and a hot water supply port 150 are joined to the tank portion 110c as shown in FIG. In addition, the reinforcing plates 16 are provided on both end sides in the stacking direction.
0 is joined.

Next, the essential part of the present invention will be described. A flange portion 111b is provided on the outer peripheral portion of the tube plates 111 and 112, and a punching portion 111c that forms a U-shaped flowing water passage 110a is provided on the inner side of the tube plates 111 and 112. When
The flange portion 111b and the embossed portion 111c are in contact with each other. The contact surface is C
It is joined with a u-based brazing material. In the present invention, the portion where the flange portions 111b are joined is referred to as the joining portion 113.
I am trying.

As shown in FIG. 1, the joint portion 113 is formed such that its length is longer on the lower side than on the upper side of the tube 110 (X <Y).

Next, the operation of the heat exchanger 100 based on the above configuration and its function and effect will be described. Hot water is
A running water passage 1 formed from the hot water inlet 140 of the heat exchanger 100 into one tank portion 110c of each tube 110 and formed from the one tank portion 110c to the flat tube portion 110b.
10a, flows into the other tank portion 110c, and flows out from the other tank portion 110c through the tap hole 150.

On the other hand, as shown in FIG. 1, the combustion gas flows from the upper side to the lower side of the heat exchanger 100, and when passing through the heat exchanger 100, heat is exchanged with the hot water to heat the hot water. . At this time, the combustion gas contains at least the heat exchanger 10.
On the outlet side of 0, the temperature is lowered to a temperature below the dew point temperature (for example, 30 to 50 ° C.), and condensation is performed. That is, this heat exchanger 100 is
Not only the sensible heat of the combustion gas but also the latent heat released when the combustion gas is condensed can be absorbed to heat the hot water. The amount of condensed water (acidic condensed water described in the section of the related art) generated at this time is lower than the upper side of the heat exchanger 100 (tube 110) as the temperature decreases during heat exchange. More, and further drips down along the tube 110 or the fins 130.

In the present invention, even if the generated condensed water drips and adheres to the joint portion 113 on the lower side of the tube 110, and the Cu-based brazing material is corroded, the joint portion 113 is generated.
Since it is formed to be long, it is possible to increase the time until the corrosion reaches the inner side of the tube 110, and it is possible to improve the corrosion resistance.

Further, since the combustion gas is made to flow downward from above the outside of the tube 110, it coincides with the direction in which the condensed water drops, and the ventilation resistance of the combustion gas can be reduced to improve the heat exchange efficiency. .

(Second Embodiment) A second embodiment of the present invention is shown in FIGS. In the second embodiment, a region (passage part) 100 a where the combustion gas passes through the heat exchanger 100 and a region (non-passage part) 10 where the combustion gas does not pass through the heat exchanger 100.
0b, the length of the joint portion 113 of the tube 110 in the passage portion 100a is increased.

Specifically, in the heat exchanger 100, it is efficient in heat exchange that the combustion gas is caused to flow concentratedly in the region of the tube 110 where the fins 130 are present.
This area is used as the passage portion 100a (FIG. 5). Actually, the combustion gas is passed through the passage portion 10 through an air duct or the like (not shown).
0a, and the length of the joint portion 113 of the tube 110 in this region can be changed to the other non-passage portion 100b.
To be longer than the length of the joining portion 113 at (Y
≧ X> Z).

In the first embodiment described above, mainly the condensed water of the combustion gas tends to be generated in the lower side of the tube 110, but the combustion gas is mainly generated in the tube 1.
It is also conceivable that the temperature lowers at the time of contact with the upper side of 10 to generate condensed water, and in the second embodiment, for a region where corrosion may occur due to contact with combustion gas (condensed water), Corrosion resistance can be improved.

(Third Embodiment) FIG. 7 shows a third embodiment of the present invention. The third embodiment is different from the above-described first embodiment in that at the terminal end 114 of the joint 113, at least one of the two tube plates 111 and 112 is opened to the combustion gas side.

Here, two tube plates 11 are used.
Each of 1 and 112 is opened to the combustion gas side, that is, the adjacent fin 130 side. Note that only one of the tube plates 111 and 112 may be opened.

As a result, the condensed water that drips down is removed from the joint portion 1.
Since it can be made difficult to adhere to the brazing material of No. 13, the corrosion resistance can be further improved.

(Fourth Embodiment) A fourth embodiment of the present invention is shown in FIGS. The fourth embodiment is different from the first embodiment in that the tube plates 111 and 112 are previously formed as a single plate (111), and the end portion 114 of the joint portion 113 is bent and formed. Is.

The tube plate 111 is integrally formed with the central connecting portion 115 as shown in FIG. Connection part 11 of this tube plate 111
Bending at 5 forms the tube 110 as if the two tube plates 111 were aligned together.

As a result, as shown in FIG. 9, the condensed water can be prevented from directly adhering to the brazing material of the joint portion 113, so that the corrosion resistance can be further improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing a main part of a first embodiment. (It is sectional drawing of the AA part in FIG. 2.)

FIG. 2 is a front view showing a heat exchanger according to the first embodiment.

3 is a view from the direction B in FIG.

FIG. 4 (a) is a top view showing a tube plate,
(B) is a front view and (c) is a bottom view.

FIG. 5 is a front view showing a heat exchanger according to a second embodiment.

6 is a cross-sectional view taken along the line CC in FIG.

FIG. 7 is a cross-sectional view showing a lower side portion of the heat exchanger according to the third embodiment.

FIG. 8 is a front view showing a tube plate according to a fourth embodiment.

FIG. 9 is a cross-sectional view showing a lower side portion of the heat exchanger according to the fourth embodiment.

[Explanation of symbols] 100 heat exchanger 100a Combustion gas passage 100b Combustion gas non-passage part 110 tubes 110a running water passage (fluid passage) 111 tube plate (first plate member) 112 Tube plate (second plate member) 113 joint 114 end 115 Connection

Claims (5)

[Claims] 1. A tube (110) having a fluid passage (110a) formed therein, wherein the inner fluid flowing through the fluid passage (110a) and the outside of the tube (110) condense during heat exchange. A heat exchanger that performs heat exchange with an external fluid that generates acidic condensed water, wherein the tube (110) is a first plate-shaped member (111).
And the second plate member (112) are brazed and joined together,
A joint part (113) is formed between an inner side where the fluid passage (110a) is formed and an outer side where the outer fluid flows, and the joint part (113) is the tube (110). In the heat exchanger, the lower side is formed to be longer than the upper side. 2. The heat exchanger according to claim 1, wherein the external fluid is a combustion gas and flows from the upper side to the lower side outside the tube (110). 3. A tube (110) forming a fluid passage (110a) therein, wherein the inner fluid flowing through the fluid passage (110a) and the outside of the tube (110) condense during heat exchange. A heat exchanger that performs heat exchange with an external fluid that generates acidic condensed water, wherein the tube (110) is a first plate-shaped member (111).
And the second plate member (112) are brazed and joined together,
A joint part (113) is formed between an inner side where the fluid passage (110a) is formed and an outer side where the outer fluid flows, and the joint part (113) is the tube (110). The heat exchanger characterized in that the passage portion (100a) is formed to be longer than the non-passage portion (100b) of the external fluid. 4. The joint portion (11) on the long side is formed.
In the terminal portion (114) of 3), at least one of the first plate-shaped member (111) and the second plate-shaped member (112) is formed so as to open to the external fluid side. The heat exchanger according to any one of claims 1 to 3. 5. The first plate-shaped member (111) and the second plate-shaped member (112) are integrally formed by a connecting portion (115) to which both are connected, and the elongated shape is formed. End part (1) of the joint part (113)
14) The connection portion (115) is formed by bending the connection portion (115).
The heat exchanger according to any one of 1.