JP2006226536A - Corrugated pipe and heat exchanging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve heat efficiency of a secondary heat exchanger, in a heat exchanging device of a gas hot water supply/heating device comprising a primary heat exchanger and the secondary heat exchanger. <P>SOLUTION: This corrugated pipe 8 of the secondary heat exchanger 4 mounted at an upper portion of the primary heat exchanger 3 is formed on an outer periphery of a pipe as irregularity where crests 81 and grooves 82 are alternately continued around the pipe. The crests and grooves have the approximate V shape in a cross-section including a shaft core of the pipe, and a top portion 81a of the crest and a bottom portion 82a of the groove 82 have the circular arc shape on both of inner periphery and outer periphery. Moisture in an exhaust gas is condensed on a surface of the corrugated pipe, and water droplets attached to a pipe surface gather at tips of the crests and drop, even when the dew condensation is generated. Accordingly, the impairing of heat exchanging efficiency caused by remaining of water droplets on surfaces of the crests for a long period, can be prevented. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a corrugated tube used mainly in a heat exchange device.

FIG. 1 shows an example of the heat exchange device (1).
The heat exchange device (1) includes a primary heat exchanger (3) above the gas burner (20), a secondary heat exchanger (4) above the primary heat exchanger, and a water pipe (5). Water is led from the secondary heat exchanger (4) to the primary heat exchanger (3).
The water pipe passing through the secondary heat exchanger (4) is a welded fin pipe (6) in which hook-shaped fins (61) are fixed by welding at equal intervals in the length direction of the pipe.
The water pipe passing through the primary heat exchanger (3) passes through a row of metal heat absorbing plates (33) arranged in parallel.

The temperature of the combustion exhaust gas of the gas burner (20) is about 1500 ° C. near the burner, about 200 ° C. near the primary heat exchanger (3), and about 80 ° C. near the secondary heat exchanger (4).
The heat exchanger prior to the heat exchanger (1) does not have a secondary heat exchanger (4) and effectively uses the temperature of the flue gas rising through the primary heat exchanger (3). It wasn't.
1 can preliminarily heat water by effectively using the temperature of the flue gas rising through the primary heat exchanger (3) in the secondary heat exchanger (4). Therefore, thermal efficiency can be improved.

However, water in the combustion exhaust gas is condensed and water droplets adhere to the welding fin tube (6) of the secondary heat exchanger (4).
The welded fin pipe (6) has a problem that corrosion of the welded portion is accelerated by the acidic condensed water and the combustion gas of the boiler.

In view of the above problems, the applicant tried to increase the thickness of the corrugated tube (9) (Patent Document 1) used as the flexible tube shown in FIG. 6 and use it as a heat exchange tube.
As is well known, the corrugated tube (80) is formed as a concavo-convex structure in which peaks (91) and grooves (92) surrounding the tube are alternately continued.
The tube shape of Patent Document 1 is a semicircular shape in which the top of the mountain (91) has a diameter that is the maximum width of the mountain. . For this reason, it turned out that there exists a problem which reduces the heat exchange efficiency of the said secondary heat exchanger.

Therefore, the applicant has previously proposed a corrugated tube for heat exchange characterized by a cross-sectional shape of a mountain (Patent Document 2).
As shown in FIG. 4, the corrugated tube (7) is formed with ridges (71) and grooves (72) surrounding the tube alternately on the outer periphery of the tube in the length direction of the tube.
Each peak (71) is a hollow body continuous with the pipe, and as shown in FIG. 5, the cross-sectional shape of the peak (71) on the plane including the axis of the pipe is one step that swells into a substantially quadrangular shape. A substantially triangular second ridge (71b) is formed at the center of the outer peripheral surface of the ridge (71a).

  Even if moisture from outside air containing flue gas condenses on the surface of the corrugated tube (7), water droplets adhering to the mountain (71) travel along the surface of the mountain (71), and the second stage mountain part Collect at the tip (bottom end) of (71b). Since the second ridge (71b) is pointed outward, the water drainage is good. However, since the bottom of the groove (72) has a somewhat flat portion (72a), if condensation occurs on the bottom of the groove, it is difficult to move to the mountain (71) side, and water droplets stay on the groove bottom for a long time. Reduce exchange efficiency.

  However, the corrugated tube (7) shown in FIG. 5 is formed by a known bulging process in which the straight tube is moved from the inside to the tube axis direction while being sandwiched between the bulge types while being pressurized with pressurized water to form one mountain. Therefore, there is a problem that a large stress acts on the sharp part of the second ridge (71b) and a crack is likely to occur.

JP-A-6-337084 JP 2004-294010 A

  The present invention clarifies a corrugated tube suitable for heat exchange that can solve the above problems.

  The corrugated tube (8) according to claim 1 is formed on the outer periphery of the metal tube as a concavo-convex structure in which peaks (81) and grooves (82) surrounding the tube are alternately arranged, and includes a cross section including the axis of the tube , Both the peak (81) and the groove (82) are substantially V-shaped, and the top (81a) of the peak (81) and the bottom (82a) of the groove (82) are both arcuate inside and outside. It is.

  Claim 2 is the corrugated tube according to claim 1, where S1 is the cross-sectional area of the groove (82), and S2 is the area of the inner groove (63) formed inside the peak (81). It ’s big.

  According to a third aspect of the present invention, in the corrugated pipe according to the first or second aspect, a cylindrical connecting part (84) having a diameter larger than the outer peripheral diameter of the mountain is formed integrally with the pipe at the end of the pipe.

  Claim 4 arranges a primary heat exchanger (3) above a combustion heating source (2) such as a gas burner, and a secondary heat exchanger (4) above the primary heat exchanger, so that water is subjected to secondary heat exchange. In a heat exchange device for feeding water preliminarily heated in the secondary heat exchanger (4) to the primary heat exchanger (3), the corrugated tube according to any one of claims 1 to 3 8) is implemented in the secondary heat exchanger (4).

  According to the fifth aspect of the present invention, a plurality of heat exchange tubes are supported between the support walls (41a) (41a) arranged at intervals, and the end of the tube is connected to the end of another tube. In the exchange device, the corrugated tube (8) according to claim 3 is used as a heat exchange tube, and the cylindrical connecting portion (64) is passed through the support wall (41a).

  In the corrugated tube (8) according to claim 1, since the crest (81) and the groove (82) are substantially V-shaped in the cross section including the axial center of the tube, dew condensation generated on the surface of the groove (82). Quickly moves to the mountain (81) side, and dew condensation on the surface of the mountain (81) quickly moves to the tip side (lower side) of the mountain (81) and drops. Since the cross-sectional shapes of the mountain (81) and the groove (82) are substantially triangular, the radius of curvature of the arc at the top (81a) of the mountain (81) and the bottom (82a) of the groove (82) becomes small. That is, since water drainage is good, it is possible to prevent condensation from staying on the surface of the tube for a long time and reducing the efficiency of heat exchange. Further, since the substantially V-shaped peak (81) and the groove are continuous, it is possible to increase the number of peaks per unit length of the pipe without reducing the height of the peak, that is, to reduce the surface of the pipe. Increase the heat exchange rate.

Further, since the tip of the peak (81) and the bottom of the groove (82) are both arcuate on the inner periphery and outer periphery, the tip of the peak (81) can be formed even if the corrugated tube (8) is formed by bulging. In addition, extreme stress concentration in the groove (82) can be avoided, and cracking can be prevented.
In addition, the shape of the mountain (81) is substantially triangular, that is, the inner groove (83) formed inside the mountain (81) is also enlarged toward the axial center of the pipe, so the water passing through the pipe is the inner groove. It is difficult to stay in (83), and the heat exchange rate for the entire water passing through the pipe can be improved.

  The corrugated tube (8) according to claim 2 has a cross-sectional area of the groove (82) as S1 in the cross section including the axial center of the tube, and the area of the inner groove (63) formed inside the peak (81) as S2. Then, since S1 is larger than S2, that is, the area of the outer surface of the tube can be increased to increase the heat exchange rate of the corrugated tube (8).

  The corrugated pipe according to claim 3 is provided at an interval since the tubular connecting part (84) having a diameter larger than the outer peripheral diameter of the peak (81) is formed integrally with the pipe at the end of the pipe. A plurality of heat exchange tubes are supported between the support walls (41a) and (41a), and the wave exchange tube (8) is used as the heat exchange tube of the heat exchange device in which the end of the tube is connected to the end of another tube. ), When the corrugated tube (8) is damaged, the diameter of the peak (81) of the corrugated tube (8) is determined by removing the tubular connecting portion (84) from the support wall (41a). Since it is smaller than the diameter of the connecting portion (84), the corrugated tube (8) can be removed together and the corrugated tube (8) of the heat exchange device can be exchanged efficiently.

  The heat exchanging apparatus according to the fourth aspect can improve the heat exchanging efficiency because the dew condensation on the surface of the corrugated pipe (8) is good for the same reason as described in the effect of the first aspect.

  The heat exchange device according to claim 5 can efficiently exchange the corrugated tube (8) for the same reason as described in the effect of claim 3.

The corrugated tube of the present invention has been developed mainly for large heat exchangers. However, in order to make the explanation easy to understand, the heat exchanger (1 ).
Complementing the lack of explanation of the heat exchange device (1) in the conventional example and describing the differences from the heat exchange device of the present invention, the primary heat exchanger (3) and the secondary heat exchanger (4) are respectively The upper and lower surfaces are surrounded by an open bowl-shaped cover (31) (41).
Inward flanges (32) and (42) project from the lower ends of both covers (31) and (41), and drain pipes (34) and (44) are connected to both inward flanges (32) and (42). Both drain pipes (34) and (44) are led to the neutralizer (7).
The neutralizer (7) adheres to the inner surface of the cover (31) (41) and drops onto the flanges (32) (42), and is guided into the neutralizer (7) through the drain pipes (34) (44). Neutralizes and discharges acid condensed water.
The heat exchange device (1) is covered with a housing (11).

The multiple horizontal fin tubes (6) of the secondary heat exchanger (4) replace the corrugated tube (8) of the present invention.
As shown in FIG. 2, the corrugated tube (8) has irregularities in which peaks (81) and grooves (82) continue alternately in the length direction of the tube.
In the cross section including the axis of the tube, the corrugated tube (8) has a substantially V-shaped peak (81) and groove (82). The crest and the bottom of the crest have an inner periphery and an outer periphery, respectively. It is characterized by an arc shape.
The outer diameter of the peak (81) of the corrugated tube (8) is about 43 mm, the diameter of the groove bottom tube is about 20 mm, and the wall thickness is about 2 mm, 2.3 mm, and 3 mm. The pitch of the mountain (81) is about 13 mm.
The corrugated tube (81) is a metal that is excellent in heat resistance and rust resistance, has good thermal conductivity, and can be pressure-formed by bulging the peaks (81) and grooves (82), such as titanium, stainless steel, etc. Etc. are formed.

  In the cross section including the axial center of the pipe, the corrugated pipe (8) is S1 where the cross-sectional area of the groove (82) is S1 and the area of the inner groove (63) formed inside the peak (81) is S2. Is greater than S2. This means that the outer surface area of the tube is larger than the inner surface area of the tube.

In the corrugated tube (8) of the embodiment, a cylindrical connecting portion (84) having a diameter larger than the outer peripheral diameter of the mountain is formed integrally with the tube at the end. The wall surface of the cover (41) is a support wall (41a) that supports both ends of the corrugated tube (8), and the cylindrical connection portions (84) at both ends of the corrugated tube (8) are connected to the support wall (41a). ) (41a).
The cylindrical connection portion (84) is formed with an internal screw or an external screw (not shown) for connection to the connection pipes (51) and (51).

  The temperature of the combustion exhaust gas of the gas burner (20) is about 1500 ° C. near the burner, about 200 ° C. near the primary heat exchanger (3), and about 80 ° C. near the secondary heat exchanger (4).

However, even if moisture in the flue gas of the burner (20) is condensed and condensation occurs on the surface of the corrugated pipe (8) of the secondary heat exchanger (4), the slope (groove) of the mountain (81) on the pipe surface Gathered at the tip (lower end) of the mountain (81).
Since the crest (81) and the groove (82) are substantially V-shaped in the cross section including the axis of the tube, the dew condensation generated on the surface of the groove (82) quickly moves to the crest (81) side. The dew condensation on the surface of the mountain (81) quickly moves to the tip side (lower side) of the mountain (81) and drops, and the cross-sectional shapes of the mountain (81) and the groove (82) are substantially triangular, respectively. The radius of curvature of the arc at the top (81a) of (81) and the bottom (82a) of the groove (82) is reduced. That is, since water drainage is good, it is possible to prevent condensation from staying on the surface of the tube for a long time and reducing the efficiency of heat exchange.
Further, since the substantially V-shaped peak (81) and the groove are continuous, it is possible to increase the number of peaks per unit length of the pipe without reducing the height of the peak, that is, to reduce the surface of the pipe. Increase the heat exchange rate.

Further, since the tip of the peak (81) and the bottom of the groove (82) are both arcuate on the inner periphery and outer periphery, the tip of the peak (81) can be formed even if the corrugated tube (8) is formed by bulging. In addition, extreme stress concentration in the groove (82) can be avoided, and cracking can be prevented.
In addition, the shape of the mountain (81) is substantially triangular, that is, the inner groove (83) formed inside the mountain (81) is also enlarged toward the axial center of the pipe, so the water passing through the pipe is the inner groove. It is difficult to stay in (83), and the heat exchange rate for the entire water passing through the pipe can be improved.

  In the primary heat exchanger (3), since the ambient temperature is high, no condensation occurs on the pipe.

  Since the tubular connecting portion (84) having a larger diameter than the outer peripheral diameter of the peak (81) is formed integrally with the tube at the end of the corrugated tube (8), the support wall (41a) provided with a space is provided. ) (41a) When a wave-like tube (8) is used as a heat exchange tube of a heat exchange device that supports a plurality of heat exchange tubes and connects the end of the tube to the end of another tube, When the corrugated tube (8) is broken, if the cylindrical connecting portion (84) can be removed from the support wall (41a), the diameter of the peak (81) of the corrugated tube (8) will be Since it is smaller than the diameter of 84), the corrugated tube (8) can be removed together and the corrugated tube (8) of the heat exchange device can be exchanged efficiently.

The heat source (2) of the heat exchange device is not limited to the gas burner (20), and may be of any type as long as it uses the high temperature of the combustion gas.
Further, the configuration of the heat exchange device is not limited as long as the wave exchange tube (8) of the present invention is used as a heat exchange tube.

  The above description of the embodiments is for explaining the present invention, and should not be construed as limiting the invention described in the claims or reducing the scope thereof. In addition, the configuration of each part of the present invention is not limited to the above embodiment, and various modifications can be made within the technical scope described in the claims.

It is a schematic explanatory drawing of the heat exchange apparatus provided with the secondary heat exchanger. It is the figure which showed a part of corrugated tube in the cross section centering on the axial center. It is explanatory drawing which shows the support state of the edge part of a corrugated tube. It is a front view of the corrugated tube which the applicant proposed previously. It is sectional drawing of the peak of the corrugated tube of FIG. It is sectional drawing of the conventional corrugated tube.

Explanation of symbols

1 Heat Exchanger 2 Heating Source 3 Primary Heat Exchanger 4 Secondary Heat Exchanger 8 Wavy Tube
81 mountains
82 groove
83 Inner groove
84 Tube connection

Claims (5)

  On the outer periphery of the metal tube, a corrugated tube (8) is formed as irregularities in which a crest (81) and a groove (82) that go around the tube alternately and continuously. 81) and the groove (82) are substantially V-shaped, and the top (81a) of the peak (81) and the bottom (82a) of the groove (82) are arcuate tubes whose inner and outer circumferences are arcuate, respectively. .   In the cross section including the axial center of the tube, S1 is larger than S2 when the sectional area of the groove (82) is S1 and the step area of the inner groove (63) formed inside the peak (81) is S2. The corrugated tube according to claim 1.   A corrugated tube in which a tubular connecting portion (84) having a diameter larger than the outer peripheral diameter of the peak (81) is formed integrally with the tube at the end of the tube according to claim 1 or 2.   A primary heat exchanger (3) is disposed above the combustion heating source (2) such as a gas burner, a secondary heat exchanger (4) is disposed above the primary heat exchanger, and water is supplied to the secondary heat exchanger (4). A heat exchanger for feeding and leading water preheated by the secondary heat exchanger (4) to the primary heat exchanger (3), wherein the corrugated tube (8) according to any one of claims 1 to 3 is provided with a secondary The heat exchange apparatus implemented in the heat exchanger (4).   In a heat exchange device that supports a plurality of heat exchange tubes between support walls (41a) (41a) arranged at intervals, and connects the end of the tube to the end of another tube. A heat exchanging apparatus in which the corrugated tube (8) according to Item 3 is used as a heat exchanging tube, and the cylindrical connecting portion (64) is passed through the support walls (41a) (41a).

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