JPH03137534A - Heat transfer pipe and leak detecting system using this pipe - Google Patents

Abstract

PURPOSE:To detect a leak quickly by disposing an outer pipe in close contact with the outer peripheral surface of an inner pipe, by making a helical groove throughout a full length of the close contact part and by providing the opposite ends of the outer pipe with leak detecting holes communicating with the groove. CONSTITUTION:One or a plurality of helical grooves 4 are formed in the outer peripheral surface of a cylindrical smooth pipe of an inner pipe 2 throughout a full length of the pipe substantially. The part of the inner pipe 2 wherein the groove 4 is formed bulges inward to increase a heat transfer area, and thereby a rate of transfer of heat of a fluid in the pipe can be increased to 1.5 to 2.0 times higher than in an ordinary smooth pipe. An outer pipe 3 is a smooth pipe and it is fitted in a shrinkage on the outer peripheral surface of the inner pipe 2 and brought into close contact therewith by bulging or the like. The opposite ends of the outer pipe 3 and the outer peripheral surface of the inner pipe are sealed with each other as required. Moreover, leak detecting holes 5 communicating with the groove 4 are made in the opposite ends of the outer pipe 3. When a leak occurs from the pipe 2 or 3 or between the two pipes, the fluid permeates through an interface and runs into the groove 4 when the leak occurs in the close contact part of the two pipes, while the fluid runs immediately into the groove 4 when the leak occurs in the part of the groove 4. Accordingly, the leak can be detected from the detecting holes 5 quickly and easily even when it is caused by a very small damage.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a heat exchanger tube mainly used in a heat exchanger, etc., and a leakage detection system using the same.

(Prior Art) FIG. 9 is a schematic cross-sectional view of a heat exchanger that has been commonly used. are arranged so that heat exchange is performed between the high temperature (low temperature) gas A flowing in the duct 24 and the low temperature (high temperature) liquid B flowing in the heat transfer tube 26.

In the figure, 27 is a liquid inlet, 28 is an inlet header, 29 is a liquid outlet, 3o is an outlet header, 31 is a sleeve, and 32 is a cover.

(Problems to be Solved by the Invention) By the way, in the conventional heat exchanger having the heat exchanger tubes 26, when leakage occurs due to the inevitable damage to the heat exchanger tubes 26, two different fluids A and B are mixed. This could lead to various negative effects.

In other words, mixing of liquid B into gas A may impair the cleanliness of the gas, gas A and liquid B may react to cause harmful effects, or loss of liquid B may cause damage to the liquid system. This has led to various problems, such as the occurrence of gas A and liquid B, or the pressure balance between gas A and liquid B being disrupted, resulting in harmful effects.

In order to eliminate these problems, the grade of the heat exchanger tube 26 should be increased to prevent damage to the heat exchanger tube 26, or the welded part (joint part) of the heat exchanger tube 26 should be made of a casing 25 where both fluids A and B do not come in contact with each other. Measures such as placing it outside are usually taken.

However, it has been practically difficult to completely eliminate damage to the heat exchanger tubes 26 caused by corrosion of the heat exchanger tubes 26 due to fluids, cracks due to thermal stress and repeated stress, wear of parts together due to expansion, contraction, and vibration, and the like.

In view of these circumstances, the present invention provides a heat exchanger tube and a leakage detection system using the same, which can quickly detect the leakage before the fluid flowing inside and outside the tube mixes when a leakage occurs due to damage. be.

(Means for Solving the Problems) In order to achieve the above object, the heat exchanger tube of the present invention has an outer tube disposed in close contact with the outer peripheral surface of the inner tube, and a heat exchanger tube that extends over the entire length in the close contact portion of both tubes. A spiral groove is formed in the outer tube, and leak detection holes communicating with the groove are formed at both ends of the outer tube.

In addition, the leakage detection system has an outer tube disposed in close contact with the outer peripheral surface of the inner tube, a spiral groove is formed over the entire length in the close contact part of the two tubes, and a groove is formed at both ends of the outer tube. It consists of a heat transfer tube each having a communicating leak detection hole, a pump or vacuum pump that flows purge fluid into the groove of the heat transfer tube, and a leak detection device that inspects the purge fluid that has passed through the groove. be.

Furthermore, other leakage detection systems have an outer tube disposed in close contact with the outer peripheral surface of the inner tube, a spiral groove is formed over the entire length in the close contact part of both tubes, and a spiral groove is formed at both ends of the outer tube. It consists of a heat exchanger tube, each having a leak detection hole communicating with the groove and keeping the inside of the groove in a vacuum or reduced pressure state, and a pressure gauge or pressure switch connected to the leak detection hole of the heat exchanger tube.

(Function) When damage occurs to the inner and outer tubes of the heat transfer tube and fluid leaks, this fluid flows into the groove formed in the close contact portion of both tubes. The inflow of fluid into the groove can be easily detected through a leakage detection hole formed at the end of the heat transfer tube.

That is, when the purge fluid is flowed into the groove of the heat transfer tube and the purge fluid discharged from the leakage detection hole is inspected by the leakage detection device, fluid leakage can be quickly detected.

In addition, if the inside of the heat transfer tube groove is kept in a vacuum or reduced pressure state and a pressure gauge or pressure switch is connected to the leakage detection hole,
Fluid leakage can be quickly detected by pressure changes within the groove.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings.

1 and 2 are cross-sectional views of a heat exchanger tube l according to an embodiment of the present invention, in which the heat exchanger tube 1 includes an inner tube 2 and an outer tube 3 disposed in close contact with the outer peripheral surface of the inner tube 2. A spiral groove 4 is formed over the entire length of the tubes 2 and 3 in close contact with each other.

That is, the inner tube 2 is formed by forming a spiral groove 4 on the outer peripheral surface of a cylindrical smooth tube, and one or several grooves 4 are formed over substantially the entire length of the tube.

In addition, the inner tube 2 is designed so that the portion where the groove 4 is formed is bulged inward to increase the heat transfer area, and the heat transfer coefficient of the fluid flowing inside the tube is 1. It can be increased by 5 to 2.0 times.

On the other hand, the outer tube 3 is made of a normal smooth tube, and the outer circumferential surface of the inner tube 2 is shrink-fitted, the outer tube 3 is drawn, the inner tube 2 is bulged, etc. to the extent that heat transfer is not adversely affected. They are arranged in close contact with contact pressure.

Moreover, the space between both ends of the outer tube 3 and the outer circumferential surface of the inner tube 2 is sealed by seal processing such as seal welding, if necessary.

Furthermore, leak detection holes 5 are formed at both ends of the outer tube 3, respectively, and communicate with the grooves 4 of the inner tube 2.

The materials used for the inner tube 2 and the outer tube 3 include carbon steel, special steel, copper, aluminum, stainless steel, etc., depending on the purpose, and are used in various combinations.

The heat transfer tube 1 is mainly used as a heat exchanger, and heat exchange is performed by two fluids having different temperatures flowing inside the inner tube 2 and outside the outer tube 3.

If fluid leaks due to minute damage to the inner tube 2, outer tube 3, or both tubes 2 and 3, the leaked fluid will leak from both tubes 2 and 3 if they are in close contact with each other. It penetrates the interface between the tubes 2 and 3 and flows into the groove 4, and if the leakage point is in the groove 4, it immediately flows into the groove 4. This groove 4 is formed over almost the entire length of the pipe, and a leak detection hole 5 that communicates with the groove 4 is formed at the end of the pipe, so even if there is a leak due to minute damage, it can be detected quickly from the leak detection hole 5. Moreover, it can be easily detected.

Therefore, when using the heat exchanger tube, even if a leak occurs, it is possible to take measures before the two fluids flowing inside and outside the heat exchanger tube 1 mix, and various adverse effects caused by mixing of fluids can be prevented. This will improve the safety and reliability of the entire device.

FIG. 3 is a cross-sectional view of a heat exchanger tube l according to another embodiment,
This has a large number of fins 6 attached to the outer peripheral surface of the outer tube 3, and the heat transfer area on the outside of the tube is increased by 2 to 15 times. Similar to the heat exchanger tube 1 of the above embodiment, this heat exchanger tube 1 can also detect leakage quickly and easily.

In the above embodiment, the groove 4 was formed only on the inner tube 2, but in other embodiments, a spiral groove was formed on the inner circumferential surface of the outer tube 3, as shown in FIG. Alternatively, as shown in FIG. 5, a spiral groove 4 may be formed on both the outer circumferential surface of the inner tube 2 and the outer circumferential surface of the outer tube 3. These heat exchanger tubes 1 also have improved heat transfer coefficients like the heat exchanger tubes 1 of the above embodiments, and can quickly and easily detect fluid leakage.

FIG. 6 is a schematic system diagram of a leakage detection system using the heat transfer tube 1 having the above structure. Fluid leakage is detected by flowing a different type of fluid from the fluid flowing inside and outside the heat tube 1 and inspecting the purge fluid 9 that has passed through the groove 4 with a leakage detection device 11 comprising a leakage detector 10 and the like. Fluid leaks are detected using electrode-type, float-type, capacitance-type, etc. detection methods, and gas leaks are detected using various gas detectors using existing techniques. It is now possible to do so.

Since this leakage detection system can quickly detect leakage by purging, it is possible to prevent various adverse effects caused by mixing of fluids.

In addition, when using a plurality of heat exchanger tubes 1, these may be connected in parallel by piping 12 as shown by the dashed line in FIG. can function alone.

FIG. 7 is a schematic diagram of a leakage detection system according to another embodiment, in which the inside of the groove 4 of the heat exchanger tube 1 is kept in a vacuum or reduced pressure state by a vacuum device, and one of the leakage detection holes 5 is closed. A pressure gauge 13, a pressure switch 14, etc. are connected to the other leak detection hole 5.

If even a small amount of fluid leaks due to minute damage to the inner tube 2 or outer tube 3, the total volume within the groove 4 is extremely small, so even a small leak will cause the pressure within the groove 4 to rise quickly. The leakage of the fluid can be immediately detected by visually observing the pressure gauge 13 or monitoring it with a meter, or by sensing it with the pressure switch 14.

Therefore, it is possible to prevent problems caused by mixing of fluids.

FIG. 8 is a schematic sectional view of a heat exchanger using the heat exchanger tube 1 of the present invention, in which 15 is a pipe connected to the leak detection hole 5 of the heat exchanger tube 1, 16 is a tank, 17 is a purge pump, 18 is a leak detector, 19 is a casing, 20 is a duct, 21 is a ladder to the inlet, 22 is an outlet header, and 23 is a cover.

Even in this case, if even a small amount of fluid leaks, this can be quickly detected and countermeasures can be taken before the fluids mix.

(Effects of the Invention) In the heat exchanger tube according to claim 1, the outer tube is disposed in close contact with the outer peripheral surface of the inner tube, and a spiral groove is formed over the entire length in the close contact portion of both tubes, Since leak detection holes communicating with the groove are formed at both ends of the outer tube, if the tube is damaged and fluid leaks, this fluid will flow into the groove. As a result, this can be easily detected from the leakage detection hole. That is, the grooves and the leakage detection holes can quickly and easily detect leakage in the heat exchanger tube, and it is possible to take countermeasures before the fluids flowing inside and outside the heat exchanger tube mix.

In addition, in the leak detection system of the U1 claim, the purge fluid is flowed into the groove of the heat transfer tube by a pump or the like, and the purge fluid that has passed through the groove is inspected by the leak detection device. leakage can be detected even more quickly, and harmful effects caused by mixing of fluids can be prevented. As a result, the safety and reliability of the entire device can be improved.

Furthermore, in the leak detection system of claim 3, the inside of the groove of the heat exchanger tube is maintained in a vacuum or reduced pressure state, and a pressure gauge or the like is connected to the leak detection hole of the heat exchanger tube, so that fluid leakage is detected in the groove. It can be quickly detected by the pressure change inside.
The same effects as the leakage detection system described above can be achieved.

In this way, the heat exchanger tube and leakage detection system of the present invention,
It can be used even in cases where it could not be used conventionally due to the possibility of mixing fluids, and the technical and economical effects are significant.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a heat exchanger tube according to an embodiment of the present invention, FIG. 2 is a sectional view taken along line nn in FIG. 1, FIG. 3 is a sectional view of a heat exchanger tube according to another embodiment, 5 and 5 are schematic sectional views showing a part of a heat exchanger tube according to another embodiment, FIG. 6 is a schematic system diagram of a leak detection system of the present invention, and FIG. 7 is a leakage according to another embodiment. FIG. 8 is a schematic sectional view of a heat exchanger using heat exchanger tubes of the present invention, and FIG. 9 is a schematic sectional view of a heat exchanger using conventional heat exchanger tubes. 1 is a heat transfer tube, 2 is an inner tube, 3 is an outer tube, 4 is a groove, 5 is a leak detection hole, 7 is a pump, 8 is a vacuum pump, 9 is a purging fluid, 11 is a leak detection device, 13 is a pressure gauge , 14 is a pressure switch.

Claims (1)

[Claims] 1. An outer tube (3) is disposed in close contact with the outer circumferential surface of the inner tube (2), and a spiral shape is provided over the entire length in the close contact portion of both tubes (2) and (3). A groove (4) is formed at both ends of the outer tube (3).
) A heat exchanger tube characterized in that a leakage detection hole (5) communicating with each other is formed respectively. 2. The outer tube (3) is placed in close contact with the outer peripheral surface of the inner tube (2), and a spiral groove (4) is formed over the entire length in the close contact area of both tubes (2) and (3). Grooves (4) are formed at both ends of the outer tube (3).
Heat exchanger tubes (
1) and purge fluid (9) in the groove (4) of the heat transfer tube (1).
) or a vacuum pump (8), and a leakage detection device (11) that inspects the purge fluid (9) that has passed through the groove (4). . 3. The outer tube (3) is placed in close contact with the outer peripheral surface of the inner tube (2), and a spiral groove (4) is formed over the entire length in the close contact area of both tubes (2) and (3). Grooves (4) are formed at both ends of the outer tube (3).
) are formed with leak detection holes (5) communicating with the grooves (4).
A heat exchanger tube (1) whose inside is kept in a vacuum or reduced pressure state, and a pressure gauge (1) connected to a leak detection hole (5) of the heat exchanger tube (1).
3) or a pressure switch (14).