JPH0249501Y2 - - Google Patents

Description

[Detailed Description of the Invention] A. Field of Industrial Application The present invention relates to a heat exchanger that prevents leakage of one medium from contaminating the other and has high heat exchange efficiency.

B. Summary of the invention This invention is a heat exchanger that transfers heat from one medium to another via a double pipe consisting of a large diameter pipe and a small diameter pipe, in which a notch is formed in the large diameter pipe. By closing the notch with a heat collecting plate and fixing a small diameter pipe to the heat collecting plate, even if one medium leaks, it will not mix into the other medium and heat will be transferred efficiently. This is what I did.

C. Conventional technology In stationary electrical equipment such as transformers and reactors, in order to improve insulation performance and reduce the size and weight of electrical equipment, the main body of the equipment is housed in a sealed casing and insulation is provided inside the casing. Filling with media. Mineral insulating oil is most often used as an insulating medium, but recently silicone-based synthetic insulating oil and sulfur hexafluoride-based insulating gas have also been used for the purpose of flame retardant and noncombustible properties.

These insulating media have the effect of insulating electrical equipment and transferring the internal heat loss of electrical equipment to the atmosphere (secondary cooling medium).
It acts as a primary cooling medium for discharge into the air. That is, the internal heat loss of the electrical equipment is released into the atmosphere from the insulating medium through the casing.

However, when the internal loss exceeds 1KW, the cooling efficiency of the natural cooling method, which radiates heat only from the outer circumferential surface of the case to the atmosphere, is insufficient, so a dedicated radiator is provided for this purpose. It is preferable for stationary electric equipment to be maintenance-free, and as a dedicated heat radiator, it often uses a natural cooling method that naturally radiates heat into the atmosphere by circulating an insulating medium. In such a dedicated heat sink, the constant pressure specific heat of the atmosphere is approximately
Since it is extremely small at 0.28Kcal/m℃, in order to achieve sufficient cooling efficiency, the proportion of dedicated heatsinks in the entire electrical equipment must be 30-50% at 1MVA class.
In the 10MVA class, a large value of 40 to 70% is required, which requires a large space.

However, in underground substations, etc., there is not enough space, and it is difficult to install a dedicated radiator for natural cooling. Therefore, we have installed a dedicated water-cooled radiator to reduce the area occupied. Conventional Example 1 (single tube type) and Conventional Example 2 (double tube type) show shell-and-tube heat exchangers used as dedicated radiators for such water cooling systems.

FIG. 2 is a structural diagram of a single-tube heat exchanger as conventional example 1. A primary cooling medium such as insulating oil flows into the shell 2 from the supply port 1a and flows out from the discharge port 1b. On the other hand, the secondary cooling medium such as water flows into the header 4a from the supply port 3a and then passes through the inside of the cooling pipes 5a, 5b, etc. to the header 4b.
and flows out from the outlet 3b. Outlet pipe 5
Since the primary cooling medium flows on the outside and the secondary cooling medium flows on the inside sandwiching a and 5b, heat is transferred from the primary cooling medium to the secondary cooling medium via the cooling pipes 5a and 5b. That is, the primary cooling medium is cooled by the secondary cooling medium.

FIG. 3 is a structural diagram of a double-tube heat exchanger as a second conventional example. In the single-tube heat exchanger shown in Fig. 2, if the secondary cooling medium leaks into the shell 2 from the joint 7 between the flanges 6a, 6b of the shell 2 and the cooling pipes 5a, 5b, the secondary cooling medium will leak into the primary cooling medium. Since the performance of the primary cooling medium deteriorates due to mixing of the secondary cooling medium, the structure is designed to prevent this from occurring. By the way, water as a secondary cooling medium is 0.05% of mineral insulating oil as a primary cooling medium.
%, the dielectric strength will decrease by as much as 50%. In the figure, the primary cooling medium flows into the shell 9 from the supply port 8a and flows out from the discharge port 8b. On the other hand, the secondary cooling medium flows into the header 11a from the supply port 10a, passes through the inside of the cooling pipes 12a, 12b, etc., reaches the header 11b, and flows out from the discharge port 10b. The interiors of the auxiliary headers 14a and 14b are communicated through cooling pipes 13a and 13b,
The cooling pipe 1 is provided inside the cooling pipes 13a and 13b.
2a and 12b are inserted. Auxiliary header 14
a, 14b, and the inside of the cooling pipes 13a, 13b is a space, and heat moves from the primary cooling medium to the secondary cooling medium across this space, so the flange portion 15
Joint part 1 between a, 15b and cooling pipes 13a, 13b
If the primary cooling medium leaks from the flange 16
Joint part 1 between a, 16b and cooling pipes 12a, 12b
Even if the secondary cooling medium leaks from the auxiliary header 8, either medium will flow out from the outlet 19a in the auxiliary header 14a or the outlet 19b in the auxiliary header 14b. In other words, heat exchange is performed without the secondary cooling medium mixing with the primary cooling medium.

D Problems to be solved by the invention However, as mentioned above, heat transfers from the primary cooling medium to the secondary cooling medium across a space, so the secondary cooling medium has a large constant pressure specific heat (990 ~
Even if water with a temperature of 1000 Kcal/m°C is used, the cooling effect is only as good as that of a natural cooling method, and the structure is complicated and the cost is high.

Therefore, an object of the present invention is to provide a heat exchanger that eliminates such drawbacks.

E Means for solving the problem The structure of the present invention to achieve this purpose is as follows:
A large diameter pipe is airtightly passed through a shell that circulates one medium, and a small diameter pipe that circulates the other medium is inserted into the large diameter pipe to form a gap between the large diameter pipe and the small diameter pipe. The heat exchanger is characterized in that a notch is formed in the large diameter tube located in the shell, the notch is closed with a heat collecting plate, and the small diameter pipe is fixed to the heat collecting plate.

F Effect Heat is transferred from one medium to the other through the double pipe with a gap between the large diameter pipe and the small diameter pipe, so even if either medium leaks, the difference between the large diameter pipe and the small diameter pipe They flow into the gaps and do not mix with each other. On the other hand, regarding heat transfer efficiency, by making the heat collecting plate larger and extending it into one medium, heat is transferred from one medium to the heat collecting plate and large diameter pipe, and this heat is transferred to the heat collecting plate and the large diameter pipe. It is transmitted from the joint with the small diameter pipe to the small diameter pipe and then to the other medium. The heat exchanger according to the present invention has a double-pipe structure, but heat is not transmitted only through the gap as in the conventional method, but through the joints, so the heat transfer coefficient is lower than that of the conventional double-pipe structure. Much larger than the tube type.

G. Embodiments Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 1a is a sectional view showing an embodiment of the heat exchanger, and FIG. 1b is a view taken along the - arrow in FIG. 1a.
As shown in the figure, a supply port 21 and a discharge port 22 are formed in the shell 20 to circulate insulating oil as one medium (primary cooling medium).
1 and the discharge port 22 are connected to a housing or the like in which electrical equipment is housed and filled with insulating oil via a pump or the like (not shown). In this embodiment, large-diameter pipes 23a and 23b pass through the interior of the shell 20 in two rows, and both ends of each are hermetically coupled to the shell 20 by brazing or welding. Each large diameter pipe 23 located within the shell 20
A notch 24 is formed on one side of each of the large diameter pipes 23a and 23b (see FIG. 1c).
4 is closed with a single heat collecting plate 26a, and a large diameter pipe 23b
Each notch 24 is closed with one heat collecting plate 26b. The large-diameter tube and the heat collecting plate are airtightly connected at these notches by brazing or welding. Small diameter tubes 27a and 27b are formed in a zigzag shape and inserted into the insides of the large diameter tubes 23a and 23b. Small diameter pipes 27a, 27b and large diameter pipe 23a,
23b, a gap 28 is formed between the small diameter pipe 2
7a, 27b are fixed to the heat collecting plates 26a, 26b by brazing or welding inside the large diameter pipes 23a, 23b. The small diameter pipes 27a and 27b are connected to a supply means (not shown) that supplies cooling water as the other medium (secondary cooling medium). In addition, in this embodiment, cooling pipes 29a and 29b are also provided on the outer peripheral surface of the shell 20 in order to further increase heat transfer efficiency.
is fixed to allow cooling water to flow through it. If fins or the like are attached to the heat collecting plates 26a and 26b, the heat transfer efficiency will be further increased.

Next, the operation of such a heat exchanger will be explained. A pump (not shown) pumps insulating oil between the casing and the shell 20.
and the small diameter pipes 27a, 27.
When cooling water is flowed into the inside of b and the cooling pipes 29a, 29b, the heat of the insulating oil is transferred from the heat collecting plates 26a, 26b and the outer surfaces of the large diameter pipes 23a, 23b to the heat collecting plates 26a, 29b.
26b and the small diameter pipes 27a, 27b to the small diameter pipes 27a, 27b, and the small diameter pipe 27
a, 27b to the cooling water. It is also transmitted to the cooling water via the shell 20 and the cooling pipes 29a and 29b. In the unlikely event that insulating oil leaks from the joint between the large diameter pipes 23a and 23b, or the small diameter pipe 27a,
Even if cooling water leaks from the gap 27b, these
There is no possibility that one cooling medium will mix with the other. If the shell 20 and the like are housed in the tank 30 and a leak detection port 31 is provided at the bottom of the tank 30, leakage can be detected by detecting the outflow of the cooling medium from the detection port 31.

This invention has the function of a double pipe to prevent one medium from mixing with the other medium, and also increases the heat transfer coefficient to transfer heat from one medium to the other through the gap. This eliminates the drawback of double pipes, which is the small amount of water. The heat transfer coefficient of air is 0.02 to 0.024Kcal/mh℃, while that of pure iron is 58Kcal/mh℃ and that of copper is 315 to 330Kcal/mh.
℃, it can be seen that the heat transfer coefficient is much higher than that of the conventional double pipe type shown in Conventional Example 2. For the large diameter pipe, small diameter pipe, and heat collecting plate, it is preferable to use copper or a copper-based alloy, which has a high heat transfer coefficient.

In this embodiment, a case is shown in which a cooling medium for the purpose of cooling is used as the medium, but a heating medium for the purpose of heating may also be used. Further, the medium is not limited to liquid, but may be gas. In addition, in this embodiment, one small-diameter tube is inserted into each of the large-diameter tubes in a row in series, but the small-diameter tubes are branched and inserted into the large-diameter tubes in parallel. You may also do so.

H Effect of the invention As explained above, according to the invention, in a double pipe in which a small diameter pipe is inserted into a large diameter pipe, a notch is formed in the large diameter pipe, and the notch is closed with a heat collecting plate.
Since the small diameter pipe is fixed to the heat collecting plate, even if one of the media leaks, it will not only not mix into the other medium, but also
Heat is transferred directly from the heat collecting plate to the small diameter pipe without any intervening space, resulting in a high heat transfer coefficient. Furthermore, since the heat transfer coefficient is high, it can be made smaller and lighter than the conventional double-tube type, and the cost can be reduced.

[Brief explanation of the drawing]

1a to 1c relate to an embodiment of the heat exchanger according to the present invention, FIG. 1a is a sectional view, and FIG. 1b is a sectional view of FIG. 1a.
Fig. 1c is an explanatory diagram for explaining the structure, Figs. 2 and 3 relate to a conventional heat exchanger, Fig. 2 is a structural diagram showing conventional example 1, FIG. 3 is a structural diagram showing conventional example 2. 20...Ciel, 23a, 23b...Large diameter pipe,
24... Notch, 26a, 26b... Heat collecting plate, 2
7a, 27b...Small diameter pipe, 28...Gap.

Claims (1)

[Scope of utility model registration request] A large diameter pipe is airtightly passed through a shell that circulates one medium, and a small diameter pipe that circulates the other medium is inserted into the large diameter pipe to form a gap between the large diameter pipe and the small diameter pipe. In the heat exchanger, a notch is formed in the large diameter pipe located in the shell, and the notch is closed with a heat collecting plate,
A heat exchanger characterized in that a small diameter tube is fixed to the heat collecting plate.