GAS INSULATION APPARATUS

A gas insulation apparatus includes: a tank that includes a flange surrounding an opening and in which an insulating gas containing oxygen is enclosed; a lid that covers the opening; a bolt that fixes the lid to the flange; and a sealing member that is sandwiched between the flange and the lid, in which the sealing member includes a first O-ring that surrounds an entire circumference of the opening, and a second O-ring that surrounds the first O-ring, the first O-ring is made of fluorine-based rubber, and the second O-ring is made of ethylene propylene diene-based rubber.

FIELD

The present disclosure relates to a gas insulation apparatus in which an insulating gas is enclosed in a tank.

BACKGROUND

A gas insulation apparatus in which an insulating gas is enclosed in a tank is used for a high-voltage electric circuit. The gas insulation apparatus is provided with a sealing structure at a flange portion of the tank in order to prevent leakage of the insulating gas in the tank.

Patent Literature 1 discloses a gas insulation apparatus that prevents gas leakage in a tank by sandwiching a first sealing member and a second sealing member between a flange disposed at an end portion of the tank in which an insulating gas is enclosed and a lid body.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Problem to be Solved by the Invention

Sulfur hexafluoride, which has been widely used as an insulating gas, is a greenhouse gas with a global warming potential of 23500. Therefore, it has been studied to use a mixed gas of carbon dioxide and oxygen, or air, main components of which are nitrogen and oxygen as an alternative gas.

In a case where an insulating gas contains oxygen, deterioration of the sealing member is accelerated as compared with a case where sulfur hexafluoride is used as the insulating gas, and the life in which the insulating gas can be sealed is shortened. Furthermore, carbon dioxide, oxygen, and nitrogen have small molecules as compared with sulfur hexafluoride. Therefore, gases of carbon dioxide, oxygen, and nitrogen easily permeate through the sealing member.

In the gas insulation apparatus disclosed in Patent Literature 1, sulfur hexafluoride is used as an insulating gas, and use of a mixed gas of carbon dioxide and oxygen or air as the insulating gas is not considered. For this reason, in the gas insulation apparatus disclosed in Patent Literature 1, when a mixed gas of carbon dioxide and oxygen or air is used as the insulating gas, there is a problem that deterioration of the sealing member is accelerated by oxygen, the life in which the insulating gas can be sealed is shortened, or the insulating gas leaks while permeating through the sealing member.

The present disclosure has been made in view of the above, and an object of the present disclosure is to obtain a gas insulation apparatus in which an insulating gas containing oxygen is less likely to leak while permeating through a sealing member, the occurrence of shortening of the life in which the insulating gas can be sealed, which is caused due to deterioration of the sealing member by oxygen, is reduced.

Means to Solve the Problem

In order to solve the above-mentioned problems and achieve the object, a gas insulation apparatus according to the present disclosure includes: a tank that includes a flange surrounding an opening and in which an insulating gas containing oxygen is enclosed; a lid that covers the opening; a bolt that fixes the lid to the flange; and a sealing member that is sandwiched between the flange and the lid. The sealing member includes a first sealing member that surrounds an entire circumference of the opening, and a second sealing member that surrounds the first sealing member. The first sealing member is made of fluorine-based rubber, and the second sealing member is made of ethylene propylene diene-based rubber. At least one of the first sealing member and the second sealing member is an O-ring.

Effects of the Invention

According to the present disclosure, it is possible to achieve the effect of providing a gas insulation apparatus in which an insulating gas containing oxygen is less likely to leak while permeating through a sealing member, the occurrence of shortening of the life in which the insulating gas can be sealed, which is caused due to deterioration of the sealing member by oxygen, is reduced.

DESCRIPTION OF EMBODIMENTS

Hereinafter, a gas insulation apparatus according to embodiments will be described in detail with reference to the drawings.

First Embodiment

FIG.1is a cross-sectional view of a gas insulation apparatus according to the first embodiment at an end portion where an opening is formed in a tank.FIG.2is a side view of a portion of the gas insulation apparatus according to the first embodiment where the opening is formed in the tank. A gas insulation apparatus50according to the first embodiment includes a cylindrical tank6in which an insulating gas is enclosed and a lid3that covers an opening6aformed at an end portion of the tank6. The end portion of the tank6is formed with a flange5. In the lid3and the flange5, holes3aand5cthrough which bolts4pass are formed. The lid3is attached to the flange5by tightening nuts7onto the bolts4that pass through the holes3aand holes5c. The flange5is formed with annular grooves5aand5bthat surround the opening6a. The diameter of the annular groove5ais smaller than the diameter of the annular groove5b. A first O-ring1that is a first sealing member is disposed in the annular groove5a, and a second O-ring2that is a second sealing member is disposed in the annular groove5b. The second O-ring2that is the second sealing member surrounds the first O-ring1that is the first sealing member. The first O-ring1and the second O-ring2have circular cross sections and are disposed and positioned within the annular grooves5aand5b. The first O-ring1and the second O-ring2are compressed by being sandwiched between the flange5and the lid3. The first O-ring1is formed using fluorine-based rubber as a material. For example, as the first O-ring1, an O-ring formed using fluorine-based rubber, a main component of which is a copolymer with poly vinylidene difluoride indicated by an identification symbol FKM-70 representing the type of material in JIS B 2401, as a material, can be applied.

The second O-ring2is formed using ethylene propylene diene-based rubber that is classified as an M group in JIS K 6397 as a material. For example, as the second O-ring2, an O-ring formed using ethylene propylene diene-based rubber, a main component of which is a copolymer of ethylene and propylene, and the like, indicated by an identification symbol EPDM-70 indicating the type of material in JIS B 2401, as a material, can be applied.

The insulating gas is not limited to a specific composition as long as the insulating gas is a gas containing oxygen, and is preferably a mixed gas of nitrogen and oxygen or a mixed gas of carbon dioxide and oxygen from the viewpoint of insulating property, boiling point, and environmental compatibility.

In a case where a mixed gas of nitrogen and oxygen is used as the insulating gas, the mixing ratio of nitrogen and oxygen is preferably close to the composition of air, specifically, for nitrogen from 70% to 90% and for oxygen from 10% to 30% from the viewpoint of safety. Furthermore, the pressure is preferably from 0.7 MPa abs to 0.9 MPa abs from the viewpoint of insulating property.

In a case where a mixed gas of carbon dioxide and oxygen is used as the insulating gas, the mixing ratio of carbon dioxide and oxygen is preferably for carbon dioxide from 60% to 80% and for oxygen from 20% to 40% from the viewpoint of safety and insulating property. Furthermore, the pressure is preferably from 0.8 MPa abs to 1.0 MPa abs from the viewpoint of insulating property.

The first O-ring1formed using fluorine-based rubber as a material has high deterioration resistance to oxygen and low gas permeability as compared with the second O-ring2formed using ethylene propylene diene-based rubber as a material. On the other hand, fluorine-based rubber changes from a rubber state to a glass state and becomes hard at a low temperature. Therefore, gas sealability of the first O-ring1is lower than that of the second O-ring2at a low temperature.

In the gas insulation apparatus50according to the first embodiment, the first O-ring1is disposed on the inner diameter side of the flange5, and the second O-ring2is disposed on the outer diameter side of the flange5. Therefore, the insulating gas in the tank6is in contact with the first O-ring1. The first O-ring1is formed using fluorine-based rubber having high deterioration resistance to oxygen as a material. Therefore, the insulating gas is less likely to leak even if the insulating gas containing oxygen is enclosed in the tank6. Therefore, the life, in which the insulating gas can be sealed, of the gas insulation apparatus50according to the first embodiment is less likely to be shortened. Furthermore, the first O-ring1has low gas permeability. Therefore, the insulating gas enclosed in the tank6is less likely to leak out through the first O-ring1. Moreover, the second O-ring2that surrounds the first O-ring1is less likely to deteriorate in gas sealability even at a low temperature. Therefore, the insulating gas is less likely to leak even in a case where the gas insulation apparatus50is exposed to a low temperature environment.

Second Embodiment

FIG.3is a cross-sectional view of a gas insulation apparatus according to the second embodiment at an end portion where an opening is formed in a tank. In the gas insulation apparatus50according to the second embodiment, the first sealing member is a first packing8. The first packing8has an annular shape that surrounds an entire circumference of the opening6a. Furthermore, the first packing8has a rectangular cross section. The first packing8is formed using fluorine-based rubber as a material. The flange5is not formed with an annular groove at a portion where the first packing8is disposed, and only formed with the annular groove5bwhere the second O-ring2is disposed. Other details in the second embodiment are similar to those of the gas insulation apparatus50according to the first embodiment. Therefore, duplicated descriptions thereof are omitted.

In the gas insulation apparatus50according to the second embodiment, the first packing8having a rectangular cross section can be disposed between the flange5and the lid3without forming an annular groove. Therefore, there is no need to form an annular groove for disposing the first sealing member in the flange5, and thus the processing cost of the flange5can be reduced. Furthermore, an annular groove for disposing the first sealing member is unnecessary. Therefore, a distance between the first sealing member and the second sealing member can be made smaller than that in the gas insulation apparatus50according to the first embodiment.

Third Embodiment

FIG.4is a cross-sectional view of a gas insulation apparatus according to the third embodiment at an end portion where an opening is formed in a tank. In the gas insulation apparatus50according to the third embodiment, the second sealing member is a second packing10. The second packing10has an annular shape that surrounds the first O-ring1that is the first sealing member. Furthermore, the second packing10has a rectangular cross section. The second packing10is formed using ethylene propylene diene-based rubber as a material. The flange5is not formed with an annular groove at a portion where the second packing10is disposed, and only formed with the annular groove5awhere the first O-ring1is disposed. Other details in the third embodiment are similar to those of the gas insulation apparatus50according to the first embodiment. Therefore, duplicated descriptions thereof are omitted.

In the gas insulation apparatus50according to the third embodiment, the second packing10having a rectangular cross section can be disposed between the flange5and the lid3without forming an annular groove. Therefore, there is no need to form an annular groove for disposing the second sealing member in the flange5, and thus the processing cost of the flange5can be reduced. Furthermore, an annular groove for disposing the second sealing member is unnecessary. Therefore, a distance between the first sealing member and the second sealing member can be made smaller than that in the gas insulation apparatus50according to the first embodiment.

Fourth Embodiment

FIG.5is a cross-sectional view of a gas insulation apparatus according to the fourth embodiment at an end portion where an opening is formed in a tank. In the gas insulation apparatus50according to the fourth embodiment, silicone sealant9is filled in the holes3aand5cthrough which the bolts4pass, and also filled in a space on the flange5on the outer edge side of the portion where the second sealing member is disposed. Other details in the fourth embodiment are similar to those of the gas insulation apparatus50according to the first embodiment. Therefore, duplicated descriptions thereof are omitted. Note that the silicone sealant9is sufficient to be disposed in at least the space on the flange5on the outer edge side of the portion where the second sealing member is disposed, and the silicone sealant9may not be disposed in the holes3aand5cthrough which the bolts4pass.

As the silicone sealant9, condensation reaction curable liquid silicone rubber of one liquid type can be applied.

The gas insulation apparatus50according to the fourth embodiment can prevent moisture from entering from bolt holes and the outer edge portion of the flange5, and thus rusting of the flange5can be prevented. Therefore, the gas insulation apparatus50according to the fourth embodiment can reduce gaps from being formed between the first O-ring1that is the first sealing member, the second O-ring2, and the flange5due to the generation of rust on the flange5. Therefore, it is possible to reduce leakage of the insulating gas enclosed in the tank6.

Fifth Embodiment

FIG.6is a cross-sectional view of a gas insulation apparatus according to the fifth embodiment at an end portion where an opening is formed in a tank. In the gas insulation apparatus50according to the fifth embodiment, silicone sealant9is filled in the holes3aand5cthrough which the bolts4pass, and also filled in a space on the flange5on the outer edge side of the portion where the second sealing member is disposed. Other details in the fifth embodiment are similar to those of the gas insulation apparatus50according to the second embodiment. Therefore, duplicated descriptions thereof are omitted. Note that the silicone sealant9is sufficient to be disposed in at least the space on the flange5on the outer edge side of the portion where the second sealing member is disposed, and the silicone sealant9may not be disposed in the holes3aand5cthrough which the bolts4pass.

In the gas insulation apparatus50according to the fifth embodiment, there is no need to form an annular groove for disposing the first sealing member in the flange5. Therefore, processing cost of the flange5can be reduced. Furthermore, an annular groove for disposing the first sealing member is unnecessary. Therefore, a distance between the first sealing member and the second sealing member can be made smaller than that in the gas insulation apparatus50according to the first embodiment. Moreover, the gas insulation apparatus50according to the fifth embodiment can reduce the roughening of the surface of the flange5due to the generation of rust on the flange5. Therefore, it is possible to reduce gaps from being formed between the first packing8that is the first sealing member, the second O-ring2, and the flange5, and thus leakage of the insulating gas enclosed in the tank6can be reduced.

Sixth Embodiment

FIG.7is a cross-sectional view of a gas insulation apparatus according to the sixth embodiment at an end portion where an opening is formed in a tank. In the gas insulation apparatus50according to the sixth embodiment, silicone sealant9is filled in the holes3aand5cthrough which the bolts4pass, and also filled in a space on the flange5on the outer edge side of the portion where the second sealing member is disposed. Other details in the sixth embodiment are similar to those of the gas insulation apparatus50according to the third embodiment. Therefore, duplicated descriptions thereof are omitted. Note that the silicone sealant9is sufficient to be disposed in at least the space on the flange5on the outer edge side of the portion where the second sealing member is disposed, and the silicone sealant9may not be disposed in the holes3aand5cthrough which the bolts4pass.

In the gas insulation apparatus50according to the sixth embodiment, there is no need to form an annular groove for disposing the second sealing member in the flange5. Therefore, processing cost of the flange5can be reduced. Furthermore, an annular groove for disposing the second sealing member is unnecessary. Therefore, a distance between the first sealing member and the second sealing member can be made smaller than that in the gas insulation apparatus50according to the first embodiment. Moreover, the gas insulation apparatus50according to the sixth embodiment can reduce the roughening of the surface of the flange5due to the generation of rust on the flange5. Therefore, it is possible to reduce gaps from being formed between the first O-ring1that is the first sealing member, the second packing10, and the flange5, thus leakage of the insulating gas enclosed in the tank6can be reduced.

The above configurations illustrated in the embodiments are examples of the contents, and can be combined with other known techniques, and the above configurations can be partly omitted or changed without departing from the gist.

REFERENCE SIGNS LIST