JPH0549127A - Gas insulating electric equipment - Google Patents

Abstract

PURPOSE:To get a gas insulating electric equipment which can evaporate liquefied gas with terrestrial heat without providing a heater requiring heating control, its operation, and maintenance and management. CONSTITUTION:A connection pipe 16, which communicates with the opening 15 provided at the bottom of a tank 2 charged with insulating gas 3, is extended and buried in the ground, and one end of this buried connection pipe 16 is shut to form a reservoir 17, and also in the reservoir 17, the tubular wall of the connection pipe 16 is constituted of a member favorable in heat conductivity, and liquefied gas 4, which is generated, being dewed by the inwall of the tank 2, and is standing in the reservoir 17, is evaporated being heated with terrestrial heat, and is returned into the tank 2 again as insulating gas 3. Thereby, even if the tank 2 dews in the rigoroud winter of a cold district, the liquefied gas 4 is evaporated effectively by terrestrial; heat, so the pressure drop of the insulating gas 3 inside the tank 2 can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to gas-insulated electric equipment used in cold regions.

[0002]

2. Description of the Related Art SF ₆ gas is an inert gas having excellent insulation, heat resistance and arc resistance, and it is used as an insulating, arc extinguishing or cooling medium in gas circuit breakers, transformers and pipelines. Gas-insulated electrical equipment such as power transmission lines and gas-insulated switchgear are widely used. However, since SF ₆ gas has a property of liquefying at a low temperature, the gas pressure inside the equipment may decrease at a low temperature of −40 ° C., for example, and the required insulation performance and arc extinction performance may not be satisfied. The lowering of the gas pressure due to liquefaction at low temperatures is more pronounced as the filling pressure inside the equipment is higher. Therefore, for gas-insulated electrical equipment used in cold regions, install the entire equipment inside the building, cover the tank with a heat insulating material, or cover the entire equipment or the tank to prevent the temperature of the equipment tank from decreasing. Measures are taken such as providing a heater for heating and mixing SF ₆ gas with other insulating gas.
6 and 7 are a side view and a front view of a conventional gas circuit breaker disclosed in Japanese Utility Model Publication No. 62-9630. In the figure, 1 is a blocking section provided for each phase, 2 is this blocking section 1
, 3 is an insulating gas filled inside the tank 2 at a pressure higher than atmospheric pressure, and 4 is a liquefied gas produced by dew condensation of the insulating gas 3 on the inner wall of the tank 2 at a low temperature. is there. Reference numeral 5 denotes a tank bottom, which has a structure such that the liquefied gas 4 is easily collected in a recess 6 formed in the tank bottom 5. Reference numeral 7 is a pressure equalizing pipe that communicates between the three tanks, and 8 is a heater that heats each recess 6, which is energized by a power supply 9. Reference numeral 10 denotes a control housing having an operating device 11 inside.

Next, the operation will be described. In the winter in cold regions, the atmospheric temperature decreases and the internal pressure of the insulating gas 3 filled at a pressure higher than the atmospheric pressure decreases. However, when the temperature falls to a specific temperature according to the filling pressure, the insulating gas 3 is filled with the insulating gas 3. Condensation begins on the inner wall of the. The liquefied gas 4 generated by this dew condensation becomes droplets and descends along the inner wall of the tank, and accumulates in the recess 6 as a liquid via the inclined surface of the tank bottom 5. When the atmospheric temperature further decreases and becomes lower than the dew condensation start temperature, the pressure of the insulating gas 3 inside the tank sharply decreases. Therefore, in order to prevent this, the liquefied gas 4 accumulated in the recess 6 of the tank bottom 5 is heated by the heater. It is locally heated and warmed by 8 and again vaporized and returned to the insulating gas 3. Even if a part of the liquefied gas 4 remains without being vaporized due to a large amount of dew condensation in the tank 2 of a certain phase due to local cooling by the cold wind, each tank 2 is connected by the pressure equalizing pipe 7 The pressure of the insulating gas 3 inside is kept substantially uniform. Generally, the gas circuit breaker is designed so that it can be operated without any trouble even if the gas pressure is reduced to about 10% of the normal state, so that a slight amount of liquefied gas 4 does not vaporize as described above. Even if it remains, the gas circuit breaker can operate normally.

[0004]

Since the conventional gas circuit breaker is constructed as described above, in order to vaporize the liquefied gas 4 produced by the condensation of the insulating gas 3, a heater for heating is used. 8 and a control device for controlling the heater are required, and a cost for operating and maintaining them is also required, resulting in a problem of high cost.

The present invention has been made in order to solve the above problems, and is a gas which can vaporize a liquefied gas by geothermal heat without providing a heater which requires heating control and its operation and maintenance management. The purpose is to obtain insulated electrical equipment.

[0006]

In a gas-insulated electric device according to the present invention, a connecting pipe communicating with an opening provided at a bottom of a tank is extended and buried underground, and a liquid of liquefied gas is underground in the connecting pipe. It has a reservoir.

Further, a liquid reservoir is provided near the bottom of the tank, and a heat transfer means for transmitting geothermal heat to the liquid reservoir is provided.

[0008]

In the present invention, the liquefied gas on the inner wall of the tank naturally descends due to gravity, passes through the bottom of the tank, and collects in the liquid reservoir buried underground, and the liquefied gas in the liquid reservoir is warmed by the geothermal heat and re-heated again. It vaporizes and becomes an insulating gas that is returned to the tank.

Further, by providing a heat transfer means for transferring geothermal heat to the liquid reservoir provided near the bottom of the tank, the liquefied gas generated on the inner wall of the tank is quickly accumulated in the liquid reservoir, and in this liquid reservoir. The vaporized insulating gas is promptly returned to the tank.

[0010]

EXAMPLES Example 1. Hereinafter, a first embodiment of the present invention will be described with reference to FIG.
Will be described. In FIG. 1, 1 to 5 are the same as those in FIG. 6 of the conventional example, 14 is the ground surface on which the gas-insulated electrical equipment of this embodiment is installed, and 15 is a shutoff part 1, an insulating gas 3 and a liquefied gas 4 are incorporated. An opening provided in the bottom 5 of the tank 2,
Reference numeral 16 is a connection pipe that communicates with the opening 15, and part of it is buried underground. 17 is a connecting pipe 16 buried underground
In the liquid reservoir 17 formed by closing one end thereof, the pipe wall of the connection pipe 16 in the liquid reservoir 17 is made of a member having good thermal conductivity. Reference numeral 19 is a heat insulating member that shields a portion of the connecting pipe 16 above the ground surface 14 from atmospheric temperature.

Next, the operation of the first embodiment will be described. When the atmospheric temperature decreases to a specific temperature of 0 ° C. or less in the winter of a cold region, the insulating gas 3 is condensed on the inner wall 2 of the tank 2. The liquefied gas 4 generated by this dew drops through the bottom portion 5 and the opening portion 15 of the tank 2 to the connection pipe 16 arranged below the bottom portion 5 by gravity, and is buried underground. It reaches the liquid reservoir 17 of the connection pipe 16. Since the liquid reservoir 17 is warmed by underground geothermal heat and is higher than the atmospheric temperature, that is, the temperature of the tank 2 by 10 degrees Celsius or more and several tens of degrees Celsius, the liquefied gas 4 accumulated in the liquid reservoir 17 is vaporized, It becomes insulating gas 3 again and is routed through the connecting pipe 16 to the tank 2
Returned to inside. At this time, the gas flow rate Q returned to the tank 2 per unit time is given by the product of the gas pressure difference P between the liquid reservoir 17 and the tank 2 and the conductance C of the connection pipe 16. Although the internal pressure of the tank 2 decreases as the atmospheric temperature decreases, the temperature difference between the atmosphere and the underground, and hence the gas pressure difference P between the tank 2 and the liquid reservoir 17, increases,
Since the gas flow rate Q of the insulating gas 3 vaporized in the liquid reservoir 17 and returned to the tank 2 increases, the decrease in the internal pressure of the tank 2 can be improved. Since the temperature of the connecting pipe 16 is kept higher than the atmospheric temperature by the heat insulating member 19, the liquid reservoir
The insulating gas 3 vaporized in 17 is rarely condensed again on the inner wall of the connecting pipe 16, and most of the insulating gas 3 is returned to the tank 2.

In the conventional gas circuit breaker (FIGS. 6 and 7), the tank bottom 5 must be provided with a recess 6, and it is difficult to form the recess 6 in the tank 2 formed of a thick plate, and it is usually difficult to form the recess 6. Although there is a problem that the expensive tank 2 becomes more and more expensive, according to the first embodiment, it is sufficient to provide the opening 15 in the tank bottom portion 5 as described above, and the tank 2 can be economically manufactured. ..

Embodiment 2. FIG. 2 shows a second embodiment of the present invention, in which the bottom portion 5 of the same tank 2 is provided with two openings 15 at two locations, and the connection pipe 16 forms a liquid reservoir 17a without closing in the underground. The openings 15 at the points are connected to each other. According to the second embodiment, the transfer area of geothermal heat is increased, and the conductance C of the gas flow path of the connection pipe 16 is twice as large as that of the first embodiment, so that a more excellent effect is exhibited.

Example 3. FIG. 3 shows Embodiment 3 of the present invention. An opening 15 is provided in the bottom portion 5 of the three-phase tank 2, and the connection pipe 16 has a liquid reservoir 17 in the underground as in Embodiment 2.
b is formed and three openings 15 are connected to each other. According to the third embodiment, the pressure equalizing pipe 7 in the conventional example (FIGS. 6 and 7) can be omitted, and the second embodiment described above can be omitted.
The same effect as that of Example 1 is obtained similarly to.

Example 4. FIG. 4 shows Embodiment 4 of the present invention, in which the liquid storage portion 17c in the underground portion is made of a metal bellows, so that the transfer area of geothermal heat is increased and the portion above the ground surface 14 of the connection pipe 16 is insulated. Since the vacuum heat insulating space 19a, which has an excellent effect, is used for shielding, recondensation on the inner wall of the connecting pipe 16 is improved, and the same effect as that of the first embodiment is exhibited as in the second to third embodiments.

Embodiment 5. Although the liquid reservoirs 17 to 17c are buried underground in the above-described Embodiments 1 to 4, Embodiment 5 of the present invention, as shown in FIG.
d is arranged near the bottom 5 of the tank 2 and a heat transfer means 18 for transferring geothermal heat to the liquid reservoir 17d is provided. That is, the heat transfer means 18 in FIG. 5 is a heat pipe in which a small amount of working fluid such as CFC is sealed inside a vacuumed metal tube 18, the lower end is buried underground and the upper end is a liquid reservoir.
It is provided inside the connection pipe 16 from 17d. 19a
Is a vacuum heat insulation tube for shielding the liquid reservoir 17d from the ambient temperature, 19b is a heat insulation member for shielding the portion above the ground surface 14 of the heat pipe which is the heat transfer means 18 from the ambient temperature,
20 is a fin that effectively transfers the geothermal heat to the underground part of the heat pipe.

Since the fifth embodiment is configured as described above, when the insulating gas 3 is condensed in the cold season in winter,
Liquefied gas 4 is a liquid reservoir located near the bottom 5 of the tank.
It collects in 17d. On the other hand, since the underground portion of the heat pipe, which is the heat transfer means 18, is heated by geothermal heat, the hydraulic fluid inside the heat pipe boils, and its vapor pressure becomes a pressure wave and moves toward the liquid reservoir 17d at the speed of sound. , Liquefied gas 4 accumulated in the liquid reservoir 17d
When cooled by, the working fluid inside the heat pipe condenses and releases latent heat, liquefies and returns to the underground part of the heat pipe by the action of gravity. Therefore, the heat transfer means 18 composed of a heat pipe can transfer a large amount of geothermal heat to the liquefied gas 4 with a very small temperature difference compared with a metal rod of the same size. In the fifth embodiment, since the liquid storage portion 17d is arranged near the tank bottom portion 5, the length of the connecting pipe 16 can be significantly shortened as compared with the first to fourth embodiments. This significantly shortens the time until the liquefied gas 4 generated on the inner wall of the tank 2 is accumulated in the liquid reservoir 17d, and the conductance C of the connection pipe 16 is significantly increased. There are two new effects of significantly increasing the flow rate Q of the insulating gas 3 returned to the tank 2 after being converted into the tank 2. Due to these two new effects, according to the fifth embodiment, the pressure drop of the insulating gas 3 inside the tank 2 due to dew condensation can be improved more effectively.

Example 6. In FIG. 5 showing the fifth embodiment, the case where the recess 6 is not provided in the bottom 5 of the tank 2 is shown, but the same recess 6 in the bottom of the tank as in the conventional example shown in FIGS. 6 and 7 is used as the liquid reservoir. One end of a heat pipe may be provided in the recess 6 to serve as the heat transfer means 18 for geothermal heat.

Although the above-mentioned Examples 1 to 6 describe the gas circuit breaker filled with SF ₆ gas, the same applies to an insulating gas which may be liquefied at a low temperature, for example, a carbon fluoride gas. It can be applied to gas-insulated transformers and other gas-insulated electrical equipment.

[0020]

As described above, according to the present invention, the connection pipe communicating with the opening provided at the bottom of the tank is extended and buried underground, and the liquefied gas reservoir is provided in the underground of the connection pipe. Since it is configured, it is possible to vaporize liquefied gas by geothermal heat without installing a heater that requires heating control and its operation and maintenance management, and gas insulated electrical equipment that has improved the internal pressure drop of the tank in the severe winter of cold regions Can be obtained.

Further, since the liquid reservoir is provided near the bottom of the tank and the heat transfer means for transmitting the geothermal heat to the liquid reservoir is provided, the liquefied gas generated on the inner wall of the tank quickly accumulates in the liquid reservoir. The insulating gas vaporized in the liquid reservoir is promptly returned to the inside of the tank, which has the effect of further improving the internal pressure drop of the tank.

[Brief description of drawings]

FIG. 1 is a side view showing a first embodiment of the present invention.

FIG. 2 is a side view showing a second embodiment of the present invention.

FIG. 3 is a front view showing a third embodiment of the present invention.

FIG. 4 is a front view showing a main part of a fourth embodiment of the present invention.

FIG. 5 is a front view showing a main part of a fifth embodiment of the present invention.

FIG. 6 is a side view of a conventional gas-insulated electric device.

FIG. 7 is a front view of a conventional gas-insulated electric device.

[Explanation of symbols]

 2 Tank 3 Insulating gas 4 Liquefied gas 5 Bottom of tank 14 Underground 15 Opening 16 Connection pipe 17, 17a to 17d Liquid reservoir 18 Heat transfer means

Claims (2)

[Claims] 1. A connection pipe communicating with an opening provided at the bottom of a tank filled with an insulating gas is extended to be buried underground, and condensation is formed on the inner wall of the tank in the underground portion of the connection pipe. A gas-insulated electric device having a liquid reservoir for liquefied gas. 2. A heat transfer for transferring a geothermal heat to a liquid reservoir for liquefied gas generated by dew condensation on the inner wall of the tank near the bottom of the tank filled with the insulating gas. A gas-insulated electric device comprising means.