JPS6037684B2 - Natural circulation cooling system for multi-strand pipe installation cables - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for cooling cables installed in multiple conduits by naturally circulating cold soot in the conduits adjacent to the cables.

Conventionally, underground cables in which many cables are installed in parallel have been generally used to increase current carrying capacity.

In many cases, the cables are installed in multiple conduits arranged in parallel, and the cables are laid closely together, resulting in a large temperature rise in the cables and limiting the allowable current of the cables. For this reason, cooling pipes are buried in the soil near the cable installation pipes.
An indirect pipe cooling method is used in which water is passed through the soil and cooled through the soil, but since water is supplied using a pump,
This maintenance and management is a hassle, and the cable cannot be cooled uniformly because there is a large temperature difference between the water inlet and outlet. Therefore, we previously proposed a cooling method by circulating easily vaporized liquid along the cable without using a pump. This method is as shown in Figure 5.
The ends of the cold soot supply pipe 2', which is installed so as not to be affected by the heat from The pipe 1' is connected to the refrigerated condensing cooler 5' installed higher than the laid conduit, and the easily vaporized liquid such as water, fluorocarbon, ammonia, etc. Cables are cooled by natural circulation, and even the longest cables can be cooled almost uniformly, and maintenance is easy because no circulation equipment such as a pump is used. The present invention is a cooling method particularly applicable to existing cable lines, in which the cold soot supply pipe and the cooling pipe are combined as a bare pipe, and the bare pipe is connected to an empty pipe line or a pipe installed close to the cable. If there is a conduit, the cable is drawn into that conduit to cool it.

That is, as shown in Fig. 2, the refrigerant supply pipe is an insulated pipe 1, which is a normal metal pipe 2 coated with a heat insulating material 3, and the cooling pipe is a non-insulated pipe 4, which is a metal pipe as it is (the metal pipe is usually made of steel). These insulated pipes and non-insulated pipes 4 are twisted together at a long pitch or without twisting to form a bare pipe A of the cable, or a pipe line provided adjacent to the cable. The cable ○ drawn into B is cooled. Figure 1 shows an example of cooling cable ○ using such a bare pipe A. At one end of the bare pipe A, the insulated pipe 1 and the non-insulated pipe 4 are connected 5, and the bare pipe is connected at the base. A is passed through the condensing cooler 6 installed higher than the conduit B where A is installed, and water, fluorocarbons,
The cold soot 7 is filled with a liquid that easily vaporizes, such as ammonia.The cold soot 7 is vaporized by the heat from the cable in the non-insulated pipe 4, becomes lighter, and flows into the condensing cooler 6, where it is cooled. It liquefies and flows into the insulated pipe 1, and from there it flows again into the non-insulated pipe 4. A head difference occurs in the cold soot 7 between the condensing cooler 6 and the insulated pipe 1 and the non-insulated pipe 4, and the refrigerant 7 naturally flows. The cable D is cooled by circulating in the direction of the arrow. Since this cooling is performed by vaporizing the cooling mixer 7, it is performed uniformly in the longitudinal direction of the cable ○. Note that the first
In the figure, reference numeral 8 indicates cooling fins of the condensing cooler 6, and if a water source is easily available, it is possible to perform cooling with water. Also, if there is a gap between the bare pipe A and the conduit B into which it is drawn, the conduction of heat from the cable D to the non-insulated pipe 4 will be poor, so it is preferable to fill it with a heat-conducting filler C. , in this case, bare pipe A drawn into pipe B
Use grout, sand, or cement with a large amount of water that can be easily removed in case the drawer is to be pulled out and repaired. Furthermore, depending on the dimensions of the bare pipe A and the conduit B, two or more non-insulated pipes 4 are used as shown in FIG. In this way, the effective heat absorption area can be increased and the cooling effect can be improved. Next, as shown in Figure 4, a group of nine pipes laid 1.5 meters underground was constructed. 1~No. 4, No. 6 ~ Earth.
Insert the triplex CV cable of Iso V40$c into the conduit of M.9. 5. Bear pipe according to the present invention (a copper pipe with an inner diameter of 4 mm and a wall thickness of 2 ribs is embedded with fender tape, and a copper pipe with the same diameter as the non-insulated pipe is covered with foamed polyethylene with a thickness of 2 mm. A cooling experiment was conducted by inserting approximately 20 pieces of heat-insulating pipes (consisting of insulated pipes) and connecting a condensing cooler to the ground.
At a time when the outside temperature was 30 qo. The temperature of the conductor of the cable drawn into pipe No. 8 was 8430°C, which was about 100°C without cooling, so it can be seen that there is a cooling effect.

In this case, the ship's side. Sand cement, a mixture of sand, cement, and fly ash, was injected into the gap between the pipes in step 5. 8
The cable conductor of the conduit decreased to about 7.00. This sand cement could be washed away by a jet of water. As explained above, according to the present invention, when there is an empty conduit in a multi-strand cable installation conduit or a conduit installed close to the cable, the conduit is an insulated pipe covered with a heat insulating material. Insert the bare pipe that combines the non-insulated pipe,
The tip of the bear pipe carries air, and the base is connected to a condensing cooler installed higher than the cable conduit, and the cooling is circulated within the bear pipe.The bear pipe used for cooling the cable is Since the cable is bundled into one line, it is only necessary to have a single line to bring it in. Therefore, even if the cooling device is not placed along the cable in advance, if the cable capacity becomes insufficient at a later date, the empty line can be removed. There is an advantage that a bare pipe can be inserted into the empty conduit by using this method, and there is no need to provide a separate conduit.

In addition, the equipment cost of the cable cooling device is low, and since the cold soot is naturally circulated without using circulation equipment such as a pump, there is an advantage that efficient cooling can be performed with easy maintenance.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example of a natural circulation cooling device for a multi-pipe cable installed according to the present invention, and FIGS. 2 and 3 are cross-sectional views showing different embodiments of bare pipes used in the cooling device of the present invention. , FIG. 4 is a front view showing an example of the arrangement of a multi-striped cable conduit to which the cooling device of the present invention is applied, and FIG. 5 is an explanatory diagram showing the natural circulation cooling device for cables proposed previously. 1...Insulated pipe, 2...Metal pipe, 3...Insulating material, 4...Non-insulated pipe, 6
...Condensing cooler, 7...Cold soot, A...
・・Veper pipe consisting of insulated pipe 1 and non-insulated pipe 4, B... Pipe line into which vapor pipe A is drawn, D...
cable. Blind 1 Figure Fin 2 Figure 3 Traditional 4 Figure Key 5

Claims (1)

[Scope of Claims] 1. A pair of insulated pipes coated with a heat insulating material and non-insulated pipes in an empty conduit of a multi-line conduit in which a cable is laid or in a conduit provided close to the laid cable. A multi-line conduit installation in which pipes are inserted, the tips of the paired pipes are connected, and the bases are connected to a condensing cooler installed at a higher position than the cable conduit, and the refrigerant inside the pipes is circulated for cooling. Cable natural circulation cooling system. 2. A natural circulation cooling device for a multi-threaded conduit cable according to claim 1, characterized in that a gap between a pair of pipes and a conduit into which the pipes are inserted is filled with a heat-conducting filler.