JPH08247687A - Heat exchanger - Google Patents

Abstract

PURPOSE: To enhance the efficiency of heat exchange by a method wherein a connecting end part of a heat transfer tube so provided as to traverse a high-temperature gas passage is joined airtightly to heat transfer tube fitting holes formed in tube plates and this heat transfer tube is formed of a carbon tube. CONSTITUTION: A heat transfer tube 12 formed of a carbon tube 20 is provided between heat transfer tube fitting holes 6 formed in left and right tube plates 7 and 8 which form a high-temperature gas passage 3. A metal sleeve 21 being longer a little than the thickness of the tube plates 7 and 8 is fitted and fixed on the outer periphery of the end part of the heat transfer tube 12 to be connected with the heat transfer tube fitting holes 6, and the outside diameter of the sleeve is made smaller slightly than the inside diameter of the heat transfer tube fitting holes 6. Since the heat transfer property of the heat transfer tube 12 can be improved, accordingly, the efficiency of heat exchange can be enhanced and reduction of the size of a heat exchanger can be attained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat exchanger, and more particularly to a heat exchanger effective for recovering waste heat from high temperature gas of combustion waste gas.

[0002]

2. Description of the Related Art FIG. 4 shows an example of a conventional waste heat recovery type heat exchanger. In the figure, reference numeral 1 indicates a hot gas passage 3 through which a hot gas 2 flows downward from above. The heat exchanger body 1 is provided with a high temperature gas inlet 4 at the upper end and a high temperature gas outlet 5 at the lower end.

As shown in FIGS. 4 and 5, tube plates 7 and 8 having heat transfer tube mounting holes 6 are formed on the left and right side surfaces of the heat exchanger body 1, respectively. Header chambers 10 and 11 are formed by an outer wall 9 on the outer side of the side of 8. Further, between the heat transfer tube mounting holes 6 and 6 of the tube plates 7 and 8, a heat transfer tube 12 arranged so as to cross the high temperature gas flow path 3 is provided in the vertical direction and in the front-back direction vertical to the paper surface of FIG. Many are arranged.

The left and right header chambers 10 and 11 are divided into a plurality of upper and lower parts by a partition plate 13, and the position of the partition plate 13 is shifted by a half pitch between the left and right parts. A water supply port 14 is formed in the header chamber 10a at the bottom end, and a water supply outlet 15 is formed in the header chamber 10b at the top end.

With the above structure, the water supplied from the water supply port 14 to the lowermost header chamber 10a on the right side is the heat transfer tube 1
When passing through 2, it is heated by the hot gas 2 and guided to the leftmost lowermost header chamber 11 and then through another heat transfer tube 12 to the second header chamber 10 from the bottom on the right side. The heat is recovered by passing through another heat transfer pipe 12 to the second header chamber 11 from the bottom on the left side while flowing in a zigzag manner to recover heat, and become hot water or steam. After that, it is led out from the water supply outlet 15.

In the figure, 16 is a cleaning nozzle provided in the upper part of the heat exchanger main body 1 for cleaning the dirt of the heat transfer tube 12 by washing with water, and 17 is a drain port provided in the lower end.

In a heat exchanger using waste gas as the high temperature gas 2, for example, the temperature of the exhaust gas introduced into the heat exchanger is 135.
There is a problem that sulfuric acid corrosion occurs due to dew condensation in the heat transfer tube 12 at a temperature such as 90 ° C. and an outlet temperature of 90 ° C. Therefore, the heat transfer tube 12 and the tube plates 7 and 8 are inexpensive and have good heat conductivity. Therefore, the heat transfer tube 12 and the tube plates 7 and 8 are generally made of a stainless steel material (SUS material).
I am trying to configure it.

As a method for connecting and fixing the stainless steel heat transfer tube 12 to the heat transfer tube mounting hole 6 of the stainless steel tube plates 7 and 8, as shown in FIG. 6, the tube plates 7 and 8 and the heat transfer tube 1 are connected.
2 is fixed by welding 18, or as shown in FIG. 7, the connecting end 12a of the heat transfer tube 12 inserted into the heat transfer tube mounting hole 6 is expanded by applying a pressing force 19 from the inside. An expander system is used, in which the inner surface of the mounting hole 6 is closely fixed.

[0009]

However, since the heat transfer tube 12 made of stainless steel has a lower heat transfer property than the heat transfer tube made of steel, the heat exchange efficiency of the heat exchanger cannot be increased so much, and Since the stainless steel material has a high hardness, it is difficult to process it. Further, the fixing method by welding shown in FIG. 6 makes the welding work difficult, and the stress is generated due to the difference in thermal expansion between the heat transfer tube 12 and the tube plates 7 and 8. Therefore, there is a problem that cracks are easily generated in the welded portion, and the expander system shown in FIG.

The present invention has been made in view of the above circumstances, and makes it possible to adopt a carbon tube as the heat transfer tube, thereby significantly improving the heat exchange efficiency, and mounting the heat transfer tube of the carbon tube on the heat transfer tube. It is an object of the present invention to provide a heat exchanger that can be easily and surely fixed to a hole.

[0011]

In the heat exchanger of the present invention, a heat transfer tube is arranged so as to cross a high temperature gas passage, and a connection end portion of the heat transfer tube is provided in a heat transfer tube mounting hole formed in a tube plate. A heat exchanger having an airtightly connected structure, characterized in that the heat transfer tube is formed of a carbon tube.

Further, the present invention is characterized in that the connecting ends of the carbon tubes are hermetically connected by an O-ring fitted in a ring groove formed on the inner peripheral surface of the heat transfer tube mounting hole.

Further, a metal sleeve having a thread groove on the inner peripheral surface and having a smooth outer peripheral surface in contact with the O-ring is screwed onto the connecting end portion of the carbon tube.

Further, the metal sleeve is a stainless sleeve.

[0015]

According to the first means of the present invention, since the heat transfer tube is formed of the carbon tube, the heat transfer efficiency of the heat transfer tube can be remarkably improved and the heat exchange efficiency of the heat exchanger can be significantly increased. Therefore, miniaturization of the heat exchanger can be achieved.

In the second means, the O-ring is fitted in the ring groove formed in the inner peripheral surface of the heat transfer tube mounting hole of the tube plate so that the connecting end portion of the carbon tube is airtightly connected. The tube sheet and the carbon tube can be easily connected.

In the third means, a metal sleeve having a thread groove on the inner peripheral surface and a smooth outer peripheral surface in contact with the O-ring is screwed on the connecting end portion of the carbon tube. The sleeve and the sleeve are airtightly held by screwing, and the smooth outer peripheral surface of the metal sleeve and the O-ring are airtightly adhered to each other, so that the tubesheet and the carbon tube are surely kept airtight.

In the fourth means, since the metal sleeve is made of stainless steel, the carbon tube and the stainless steel sleeve will not be corroded by sulfuric acid.
In particular, it can be suitably used for a heat exchanger that recovers the waste heat of combustion waste gas.

[0019]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 show an embodiment of the present invention applied to the heat exchangers of FIGS. 4 and 5, wherein the same reference numerals in the drawings represent the same things. There is.

As shown in FIG. 1, the carbon tube 20 is provided between the heat transfer tube mounting holes 6 and 6 formed in the left and right tube plates 7 and 8 forming the high temperature gas flow path 3 as shown in FIG. The heat transfer tube 12 formed by is arranged.

Heat transfer tube 1 comprising the carbon tube 20
2, a metal sleeve 21 a little longer than the thickness of the tube plates 7 and 8 is fitted and fixed to the outer circumference of the ends connected to the heat transfer tube mounting holes 6 and 6, and the outer diameter of the metal sleeve 21 is the same as that of the heat transfer tube. It is slightly smaller than the inner diameter of the heat pipe mounting hole 6.

As shown in FIG. 2, the metal sleeve 21 has a thread groove 22 formed on the inner peripheral surface thereof, and the connection end portion 12a of the carbon tube 20 is screwed into the thread groove 22 of the metal sleeve 21. By inserting the metal sleeve 21
The carbon tube 20 and the carbon tube 20 are integrally fixed. At this time, the carbon tube 20 is replaced with the metal sleeve 2.
By being strongly screwed into 1, the carbon tube 2
A screw groove is formed on the outer periphery of 0 to be airtightly fixed.

As shown in FIG. 1, the heat transfer tube mounting hole 6 is formed.
A ring groove 23 is formed in an annular shape on the inner peripheral surface of the, and an O-ring 24 is fitted in the ring groove 23. For the O-ring 24, a fluorine-based rubber (for example, JISB2401) excellent in heat resistance and chemical resistance is used.

As described above, the heat transfer tube 12 in which the metal sleeve 21 is fitted and fixed on the outer periphery of the connecting end portion 12a of the carbon tube 20 is connected to the O-ring 2 by the metal sleeve 21.
The heat exchanger is arranged so as to be tightly inserted into the inner circumference of No. 4.

The metal sleeve 21 can be made of various metals such as steel when the high temperature gas 2 is a gas which is free from sulfuric acid corrosion.

On the other hand, when the high temperature gas 2 is a gas which causes a problem of sulfuric acid corrosion such as combustion waste gas, the metal sleeve 2 is used.
1 is a stainless sleeve 25. In this case, the tube sheets 7 and 8 are also made of stainless steel.

Further, when the airtightness between the tube plates 7 and 8 and the heat transfer tube 12 is not strictly required, as shown in FIG. 3, the ring groove 23 is formed in the inner peripheral surface of the heat transfer tube mounting hole 6. Once formed, the O-ring 24 is fitted and arranged in the ring groove 23, and the connecting end 12 of the carbon tube 20 is inserted into the O-ring 24.
It is also possible to directly insert and connect a.

The operation of the above embodiment will be described below.

As shown in FIGS. 1 to 3, since the heat transfer tube 12 is formed of the carbon tube 20, the heat transfer performance of the heat transfer tube 12 can be remarkably improved, and thus the heat exchange of the heat exchanger. The efficiency can be significantly increased, and the heat exchanger can be downsized.

Further, as shown in FIGS. 1 and 2, since the metal sleeve 21 having the thread groove 22 formed on the inner peripheral surface thereof is screwed to the connecting end portion 12a of the carbon tube 20,
The outer peripheral surface of the carbon tube 20 having a satin shape,
The inside of an O-ring 24, which can be airtightly surrounded by a metal sleeve 21 having an improved outer peripheral surface, and which is disposed on the inner peripheral surface of the heat transfer tube mounting hole 6 of the tube plates 7 and 8 via a ring groove 23. The metal sleeve 2 at the end of the carbon tube 20
Since 1 is tightly inserted, the airtightness between the metal sleeve 21 and the O-ring 24, the surfaces of which are accurately formed, can be reliably maintained, and thus the heat transfer tube including the carbon tube 20 can be maintained. The heat transfer tube mounting holes 6 of the tube plates 7 and 8 in an airtight manner so as to meet the tolerance standard.
Can be fixed to.

Further, as shown in FIG. 3, a ring groove 23 is formed on the inner peripheral surface of the heat transfer tube mounting hole 6, and the ring groove 23 is formed.
By inserting the O-ring 24 into the O-ring 24 and directly inserting and connecting the connecting end 12a of the carbon tube 20 into the O-ring 24, the airtightness between the tube sheets 7 and 8 and the heat transfer tube 12 is improved. If it is not strictly required, the connecting plates 7 and 8 and the heat transfer tube 12 can be easily connected.

Further, by using the stainless sleeve 25 made of stainless material as the metal sleeve 21,
Since the carbon tube 20 and the stainless sleeve 25 do not cause sulfuric acid corrosion, the carbon tube 20 and the stainless sleeve 25 can be suitably used especially for a heat exchanger for recovering waste heat of combustion waste gas.

[0034]

According to the first aspect of the invention, since the heat transfer tube is formed of the carbon tube, the heat transfer performance of the heat transfer tube can be remarkably improved, and therefore the heat exchange efficiency of the heat exchanger can be greatly improved. It is possible to increase the size of the heat exchanger and reduce the size of the heat exchanger.

According to the second aspect of the present invention, the O-ring is fitted in the ring groove formed in the inner peripheral surface of the heat transfer tube mounting hole of the tube plate to hermetically connect the connecting end of the carbon tube. It is possible to easily connect the tube sheet and the carbon tube.

According to the third aspect of the present invention, the connecting end portion of the carbon tube has a thread groove on the inner peripheral surface, and the metal sleeve having a smooth outer peripheral surface in contact with the O-ring is screwed onto the carbon tube. The metal sleeve is airtightly held by screwing, and the smooth outer peripheral surface of the metal sleeve and the O-ring are airtightly adhered, so that the airtightness of the tube sheet and the carbon tube is surely maintained.

In the invention of claim 4, since the carbon sleeve and the stainless sleeve are not corroded by sulfuric acid because the metal sleeve is a stainless sleeve, it is particularly suitable for a heat exchanger for recovering waste heat of combustion waste gas. Available for

[Brief description of drawings]

FIG. 1 is a cutaway front view of an essential part showing an embodiment of the present invention.

FIG. 2 is a cut front view showing an example of fixing the carbon tube and the metal sleeve of FIG.

FIG. 3 is a cut-away front view of a main part showing another embodiment of the present invention.

FIG. 4 is a cut front view showing an example of a waste heat recovery type heat exchanger.

5 is a cut front view showing the periphery of a part of the heat transfer tube of FIG.

FIG. 6 is a detailed view of part A of FIG. 4, showing an example of a conventional method of fixing a heat transfer tube to a tube plate.

FIG. 7 is a detailed view of a portion A of FIG. 4 showing another conventional example of a method of fixing a heat transfer tube to a tube plate.

[Explanation of symbols]

 3 High Temperature Gas Flow Path 6 Heat Transfer Tube Mounting Hole 7 Tube Plate 8 Tube Plate 12 Heat Transfer Tube 12a Connection End 20 Carbon Tube 21 Metal Sleeve 22 Screw Groove 23 Ring Groove 24 O Ring 25 Stainless Steel Sleeve

Claims (4)

[Claims] 1. A heat exchanger having a structure in which a heat transfer tube is arranged so as to cross a hot gas passage, and a connection end of the heat transfer tube is airtightly connected to a heat transfer tube mounting hole formed in a tube plate. hand,
A heat exchanger characterized in that the heat transfer tube is formed of a carbon tube. 2. The heat exchanger according to claim 1, wherein the connecting ends of the carbon tubes are hermetically connected by an O-ring fitted in a ring groove formed in the inner peripheral surface of the heat transfer tube mounting hole. . 3. A metal sleeve having a thread groove on its inner peripheral surface and having a smooth outer peripheral surface in contact with the O-ring is screwed onto the connecting end of the carbon tube.
The heat exchanger described in. 4. The heat exchanger according to claim 3, wherein the metal sleeve is a stainless sleeve.