JPS6011408B2 - Extruded insulated cable continuous cooling device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an extruded insulated cable continuous cooling device that continuously cools an extruded insulated cable during its manufacturing process.

For example, when manufacturing a crosslinked polyethylene cable, the polyethylene insulated cable obtained through an extrusion process using an extruder is immediately heat-crosslinked through a crosslinking process using a crosslinking device without being cooled, and then passed through a cooling process using a cooling device. It is cooled to about room temperature.

However, conventionally, a cooling device uses cooling water and uses the sensible heat of the water for cooling, which has the disadvantage of poor cooling efficiency and, in this connection, the disadvantage that the cooling process becomes long.

An object of the present invention is to provide an extruded insulated cable continuous cooling device that can improve cooling efficiency and effectively liquefy a vaporized cooling medium.

In the present invention, a cooling medium for boiling is used in the cooling process, and a moving extruded insulated cable is continuously and efficiently cooled by boiling in a cooling container containing the cooling medium. The cooling medium is characterized by being reliquefied in the condensing section and returned to the cooling container for reuse.

When such a cooling means is employed, if non-condensable gas is generated in the condensation area of the cooling medium, it will be fractionated in the cooling container, making it difficult to maintain sufficient cooling capacity.
In particular, it is widely known that gases such as methane are generated when CV cables are bridged. In the case of cooling in which a gas phase and a liquid phase coexist, the generation of such non-condensable gas has an adverse effect on the cooling capacity. In particular, methane has a boiling point of -164 qo and is not condensed by normal water cooling. Therefore, in the present invention, such non-condensable gas is separated by fractional distillation,
Another feature is that it prevents a decrease in cooling efficiency. As the cooling medium for boiling, for example, fluorocarbon, fluorine oil, trifluoroethyl alcohol, or the like is used.

Among these, for example, Freon R-11 (CC13F), R
-112 (CC12F/CC12F), R-113 (C
The equilibrium vapor pressure of C12F, CCIF2), etc. is as shown in Figure 1, and is primarily determined by temperature and pressure. Therefore, when the cable to be cooled enters the Freon container and its temperature is higher than the equilibrium temperature, the Freon boils, exerts latent heat of vaporization from the cable, and vaporizes. Therefore, the cable can be efficiently cooled using the latent heat of freon. Examples of fluorine oil include C8F,60, C3F,6, and C7F.
,4, C5F,2, C,oF,8, C,2F27N, etc. can be used.

The physical properties of C8F,60 (perfluorocyclic ether mixture) in such fluorine oil are as follows. Physical properties of C8F,60 Boiling point 102.20
Pour point -93pm
Vapor pressure 260 and 3 days bs
Specific gravity: 1 at 25 o'clock.
76 Viscosity 0.8 centistoke at 260 Latent heat of vaporization 21 Kcal
Nota specific heat 0.2&al
/ ℃ dielectric strength 25o0 21.
Dielectric constant of 3×10-4 or more at 7KV/side n6 25q0
1.87 Next, trifluoroethyl alcohol has a boiling point of 75°C, and it may be used alone or in a mixture with water.

For example, 85% by weight of trifluoroethyl alcohol and 1 part of water.
A mixture of 5% by weight is used. FIG. 2 shows an example of an insulated cable manufacturing apparatus including an extruded insulated cable continuous cooling device according to the present invention.

As shown in the figure, a cable core 1 passes through a turn sheave 2 and enters a crosshead 4 of an extruder 3, and its outer periphery is coated with an uncrosslinked rubber or plastic insulating material containing a crosslinking agent, thereby forming an extruded insulated cable 5.

The extruded insulated cable 5 is immediately inserted into the bridging tube 7 of the bridging device 6.
The material is heated and cross-linked.

Crosslinking is performed using, for example, an inert gas, infrared rays, ultrasonic waves, or the like. Crosslinked extruded insulated cable 5
then enters the insulated cable continuous cooling device 8 according to the invention and is cooled to room temperature.

This cooling device 8 includes a boiling cooling section 10 that boils and cools the extruded insulated cable 5 with a boiling cooling medium 9, a condensing section 11 that takes out the vaporized cooling medium 9, liquefies it, and returns it to a boiling cooling section 101. A non-condensable gas separation section 12 is connected to the condensing section 11 and separates non-condensable gas from the gaseous cooling medium by fractional distillation. The boiling cooling unit 10 includes a vertically long cylindrical cooling container 1 that is installed continuously on the bridge tube 7.
3, and this cooling container 13 is filled with Freon 9 as a vapor-liquid two-phase cooling medium 9 for boiling cooling.

The cross-linked high temperature extruded insulated cable 5 is placed in the cooling container 13
When the CFC 9 enters the inside and comes into contact with the liquid of Freon 9 (for example, R-113), the Freon 9 boils, and the extruded insulated cable 5 is vaporized by the latent heat of vaporization, becoming a gas phase. Therefore, the cooling container 13
The inside is filled with a gas-liquid two-phase cooling medium 9, in which the lower portion contains Freon 9 in a liquid phase and the upper portion contains Freon 9 in a gas phase.
The extruded insulated cable 5 is efficiently cooled by the latent heat of vaporization of the freon 9. At this time, if the section of the gas phase of the fluorocarbon 9 is set appropriately, the extruded insulated cable 5 can be gradually cooled by the gas phase fluorocarbon 9 until it reaches the liquid phase fluorocarbon 9, and the extruded insulated cable 5 suddenly becomes It can prevent cooling. This means that when comparing the heat transfer between the gas phase Freon 9 and the cable 5, the latter has an order of magnitude greater heat transfer effect. Cooling in the gas phase has the advantage that as the strength of liquid evaporation increases, the speed of the gas phase increases and the cooling effect increases, so if slow cooling is insufficient, it will work towards improving this. There is. The cooled cable 6 is led out through the seal section S. Condensing section 11
is equipped with a bypass type branch passage 14 provided in parallel with the cooling container 13, and a condenser 15 is provided in the middle of this branch passage 14, and the fluorocarbon 9 in the gas phase is passed through the branch passage 14 and condensed. into the cooling container 15, condensed and reliquefied.
I'm reverting to 3.

In the condenser 15, a cooling medium such as water is passed through the cooling pipe 15b in the container 15a, and the heat dissipation section 14 of the branch passage 14 is heated.
It exchanges heat with the fluorocarbon gas passing through a. The pressure inside the cooling container 13 is uniquely determined by the cold soot temperature determined by the amount of heat exchanged by the condenser 15 and the temperature of the cable 5 from the equilibrium vapor pressure curve as shown in FIG.

Further, the temperature inside the cooling container 13 is the same in both the gas phase and the liquid phase. The non-condensable gas separation section 12 is connected to the branch path 14 via a normally open valve 17a, and includes a reservoir tank 16, and the reservoir tank 16 is provided with a normally closed valve 17b for communicating with and shutting off the outside. Prepare,
In addition, an auxiliary cooling means 18 consisting of a water jacket or the like for cooling the reservoir tank 16 is provided.

Therefore, if non-condensable gas such as methane is generated during the cooling process of the cable 5, it is fractionated and separated in the branch path 14 and stored in the reservoir.
Gather at Batank 16.

Therefore, by closing the valve 17a and opening the valve 17b at appropriate intervals, the accumulated non-condensable gas is released. In this case, if the reservoir tank 16 is cooled by the auxiliary cooling means 18, the non-condensable gas can be collected in the reservoir tank 16 more effectively. By removing the non-condensable gas in this way, it is possible to prevent the cooling efficiency from decreasing due to the non-condensable gas. FIG. 3 shows another embodiment of the cooling device according to the present invention.

In this embodiment, the configuration of the condensing section 11 and the mounting position of the non-condensable gas separation section 12 are changed. That is, in the condensing section 11 of this embodiment, the branch path 14 is branched from the cooling container 13 and raised upward, and the container 1 of the condenser 15 is placed at the upper end of the branch path 14.
5a is connected through a lotus, and the gas phase cooling medium 9 is transferred to this container 15a.
A cooling pipe 15b for passing cooling water or the like is arranged inside the container 15a. In this way, the cooling medium 9 that has been reliquefied into a liquid phase within the container 15a of the condenser 15 is returned to the cooling container 13 by going down the same branch path 14. Furthermore, in the non-condensable gas separation section 12 of this embodiment, the reservoir tank 16 is connected to the condensing section 1.
1 via a regular valve 17a,
A normally closed valve 17b is connected to the upper part of the reservoir tank 16 to allow communication with and isolation from the outside.

In this way, non-condensable gas tends to accumulate in the upper side of the container 15a of the condensing section 11 (the side far from the cooling container 13), and since the reservoir tank 16 is connected to this position, the non-condensable gas can be efficiently condensed. Gas can be removed. In each of the above embodiments, the case where cooling is performed after cross-linking has been described, but the present invention is not limited to this. For example, in the case where cross-linking is not performed, extruded insulated cables that are cooled immediately after extrusion can be manufactured. Of course, it can also be applied.

As explained above, the extruded insulated cable continuous cooling device according to the present invention uses a boiling cooling medium and its evaporation.
The extruded insulated cable is boiled and cooled by "latent heat".
It can perform cooling more efficiently than conventional cooling devices that utilize "sensible heat."

Therefore, the length of the cooling device in the cable passing direction can be shortened, and the occupied area can be reduced. In particular, in the present invention, since non-condensable gas generated during the cable cooling process is fractionated and separated in the condensing section and removed, a decrease in cooling efficiency can be prevented and cooling can be performed efficiently.

[Brief explanation of the drawing]

Fig. 1 is a temperature-pressure characteristic diagram of CFC as a cooling medium, Fig. 2 is a schematic sectional view of an extruded insulated cable manufacturing apparatus using an example of the cooling device of the present invention, and Fig. 3 is a diagram of the cooling device according to the present invention. FIG. 7 is a sectional view of a main part of another embodiment. 8... Continuous cooling device, 9... Cooling medium for boiling cooling, 10... Boiling cooling section, 11...
・Condensation section, 12... Non-condensable gas separation section, 13.
...Cooling container, 14... Branch road, 15.
...Condenser, 16...Reservoir tank, 17
a, 17b...Valve, 18...Auxiliary cooling means. Figure 1 Figure 2 Figure 3

Claims (1)

[Scope of Claims] 1. In an extruded insulated cable continuous cooling device that continuously cools a manufactured extruded insulated cable by passing it through the cable, a cooling medium for boiling cooling is contained in a cooling container, and the cable passes through the cooling container. The cooling medium is vaporized in the cooling container, and includes a boiling cooling unit that boils and cools the cooling medium with the cooling medium, a branch path branched from the cooling container, and a condenser connected to the branch path. a condensing section that takes out the liquid, liquefies it, and returns it to the cooling container; and a non-condensable gas separation section that is connected to the condensing section and separates and removes non-condensable gas from the cooling medium in the vapor phase. An extruded insulated cable continuous cooling device characterized by: 2. The non-condensable gas separation section includes a reservoir tank connected to the condensing section, and a valve that performs control to extract the non-condensable gas accumulated in the reservoir tank. The extruded insulated cable continuous cooling device according to item 1. 3. The extruded insulated cable continuous cooling device according to claim 2, wherein the non-condensable gas separation section includes auxiliary cooling means for cooling the reservoir tank. 4 Using a vapor-liquid two-phase cooling medium for boiling cooling as the cooling medium and storing it in the cooling container, guiding the cable into the gas phase of the cooling medium and then into the liquid phase within the cooling container. An extruded insulated cable continuous cooling device according to any one of claims 1 to 3, characterized in that the extruded insulated cable continuous cooling device has a structure.