JP7282517B2 - Vacuum double-shell tank and its perlite replenishment method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a vacuum double-shell tank having an outer tank and an inner tank and a perlite replenishment method for the same.

BACKGROUND ART Conventionally, double-shell tanks are known as tanks for storing cryogenic liquids. A double-shell tank generally includes an inner tank that substantially contains a low-temperature liquid, an outer tank that covers the inner tank from the outside at a predetermined interval, and a space between the inner tank and the outer tank. and a formed heat insulating layer. The heat insulating layer is formed, for example, of granular perlite packed in the space between the tanks in a compacted state.

When constructing a double-shell tank, after the inner and outer tanks are completed, granular perlite is filled so as to fill the space between the inner and outer tanks while the inner tank is empty. Therefore, when the low-temperature liquid is supplied to the inner tank and the inner tank shrinks and deforms, the gap between the inner tank and the outer tank widens, and the perlite filled in the space between the tanks settles. When the perlite settles, a gap in which no perlite exists is generated in the inter-tank space at the top of the tank, the thickness of the heat insulating layer at the top of the tank is reduced, and the heat insulating properties of the top of the tank are reduced. Due to the deterioration of the heat insulation, cold heat from the inner tank may be transferred to the outer tank, causing frost to form on the outer tank, which may lead to corrosion of the outer tank. In addition, if the amount of heat input to the inner tank increases due to the deterioration of the heat insulating properties, the amount of boil-off gas of the low-temperature liquid increases, and the pressure in the inner tank may become excessive. Therefore, when the perlite settles to create a gap in which no perlite exists in the inter-tank space at the top of the tank, the perlite is replenished in the gap. Patent Documents 1 to 3 propose techniques for replenishing perlite in double-shell tanks.

The low-temperature tank of Patent Document 1 includes a perlite grain filling nozzle provided through an outer tank, an annular pipe attached to this nozzle, and perlite for pumping perlite grains from the outside of the tank to the perlite grain filling nozzle. and a transport device. The annular pipe is provided with downward slits for ejecting perlite grains between the inner tank and the outer tank.

In the low-temperature tank of Patent Document 2, in the vicinity of the roof nozzle provided at the top of the tank, a perlite particle injection pipe for blowing perlite together with compressed nitrogen between the inner tank and the outer tank, and from between the inner tank and the outer tank and an exhaust pipe for forced exhaust. The perlite grain injection pipe is provided with an ejector for pumping perlite. An exhaust ejector is provided in the exhaust pipe.

In the low-temperature tank of Patent Document 3, a perlite filling device is attached via a ball valve to a perlite supply pipe that extends between the side wall of the inner tank and the side wall of the outer tank. The operation of connecting the ball valve and the pearlite supply pipe to the opening of the pearlite supply pipe is performed in a seal box supplied with an inert gas.

Japanese Utility Model Laid-Open No. 6-16295 JP-A-8-121697 Japanese Patent Application Laid-Open No. 2011-106501

Some double-shell tanks have a vacuum layer in the space between the inner tank and the outer tank to suppress the heat input from the outside. Such double shell tanks are hereinafter referred to as "vacuum double shell tanks". Vacuum double-shell tanks are used, for example, for the storage of cryogenic liquids such as liquefied hydrogen.

The space between the inner and outer tanks of the vacuum double-shell tank is forcibly evacuated to vacuum over a long period of time when the tank is constructed. Once the inter-vessel space is vacuum-broken, it takes a long time to return the inter-vessel space to vacuum again. Therefore, it is desirable to suppress the decrease in the degree of vacuum in the inter-tank space of the vacuum double-shell tank even during perlite replenishment. In addition, in the low-temperature tanks of Patent Documents 1 to 3, the inter-tank space between the inner tank and the outer tank is not vacuum, and such problems are not considered.

The present invention has been made in view of the above circumstances, and an object of the present invention is to reduce the degree of vacuum in the space between the inner tank and the outer tank in a vacuum double-shell tank while suppressing a decrease in the degree of vacuum in the space between the tanks. To provide a technique for replenishing perlite to a part.

A perlite replenishing method for a vacuum double-shell tank according to one aspect of the present invention comprises an inner tank for storing a liquid in a sealed state, an outer tank covering the inner tank at a predetermined interval, the inner tank and the outer tank. A perlite replenishment method for a vacuum double-shell tank having granular perlite filled in an inter-tank space with a tank, wherein the inter-tank space is a vacuum,
While forcibly evacuating the inter-tank space, a gap formed in the inter-tank space by the sedimentation of the perlite and a perlite replenishing container in which the replenishing perlite is enclosed together with helium gas and which has a higher pressure than the inter-tank space. The replenishment perlite is supplied to the inter-tank space by communicating with each other.

Further, the vacuum double-shell tank according to one aspect of the present invention is
an inner tank in which a reservoir for storing liquid in a sealed state is formed;
an outer tank covering the inner tank with a predetermined interval;
Granular perlite filled in a vacuum inter-tank space formed between the inner tank and the outer tank;
a vacuum pump connected to the inter-tank space and forcibly exhausting the inter-tank space;
a perlite replenishing container in which replenishing perlite is sealed together with helium gas and whose internal pressure is higher than the inter-tank space;
a perlite supply pipe that penetrates the top of the outer tank and connects the space between the tanks and the inside of the perlite replenishment container;
a replenishment valve provided in the perlite supply pipe for switching between disconnection and connection between the inter-tank space and the interior of the perlite replenishment container;
While the inter-tank space is forcibly evacuated by the vacuum pump, the replenishing perlite is supplied to the inter-tank space by switching the replenishing valve so that the inter-tank space and the inside of the perlite replenishing container are connected. It is something to do.

In the vacuum double-shell tank and its perlite replenishing method, when the space between the inner tank and the outer tank communicates with the perlite replenishing container, perlite is replenished by the differential pressure between the inter-tank space and the perlite replenishing container. Replenishing perlite in the container flows into the inter-tank space. During this time, the inter-tank space between the inner and outer tanks is forcibly evacuated, and the volume of the perlite replenishing container is limited, so that the reduction in the degree of vacuum in the inter-tank space can be suppressed. Therefore, according to the vacuum double-shell tank and the method for replenishing perlite therefor, it is possible to replenish perlite in the space between the tanks while suppressing a decrease in the degree of vacuum in the space between the inner tank and the outer tank. can.

Vacuum double-shell tanks are mainly used to store cryogenic liquids such as liquefied hydrogen, and helium gas is suitable because it does not liquefy even when cryogenic liquids are stored in the inner tank.

Moreover, in the vacuum double-shell tank, the perlite replenishing container may be provided above the equator of the outer tank.

As a result, compared to the case where the perlite replenishing container is arranged on the side of the outer tank, the perlite supply pipe can be shortened, and the perlite replenishing container can be quickly discharged from the perlite replenishing container.

In the vacuum double-shell tank, the pearlite replenishing container may be detachably connected to the pearlite supply pipe by a joint.

As a result, the perlite replenishing container can be of a replaceable cassette type.

Further, a perlite replenishment method for a vacuum double-shell tank according to an aspect of the present invention includes an inner tank for storing liquid in a sealed state, an outer tank covering the inner tank with a predetermined interval, and the inner tank. A perlite replenishing method for a vacuum double-shell tank having granular perlite filled in a space between the outer tank and the outer tank, wherein the space between the tanks is a vacuum,
While forcibly exhausting the inter-tank space, the inter-tank space is communicated with a perlite replenishing container in which replenishing perlite is enclosed and which has a higher pressure than the inter-tank space and a lower pressure than the atmospheric pressure. The replenishing perlite is supplied to the inter-tank space.

Similarly, a vacuum double-shell tank according to one aspect of the present invention comprises :
an inner tank in which a reservoir for storing liquid in a sealed state is formed;
an outer tank covering the inner tank with a predetermined interval;
Granular perlite filled in a vacuum inter-tank space formed between the inner tank and the outer tank;
a perlite replenishing container in which replenishing perlite is enclosed;
a perlite supply pipe that penetrates the top of the outer tank and connects the space between the tanks and the inside of the perlite replenishment container;
a replenishment valve provided in the perlite supply pipe for switching between disconnection and connection between the inter-tank space and the inside of the perlite replenishment container;
a vacuum pump capable of switching between disconnection and connection with the perlite replenishing container and the inter-tank space,
The vacuum pump is connected to the perlite replenishing container , and after the vacuum pump forces the inside of the perlite replenishing container to be evacuated to a pressure higher than the space between the tanks and lower than the atmospheric pressure, the vacuum pump is connected to the tank. By switching the replenishment valve so that the inter-vessel space and the inside of the perlite replenishing container are connected while forcibly exhausting the inter-vessel space with the vacuum pump, The supplemental perlite is supplied.

In this case, the vacuum double-shell tank includes a first exhaust passage connecting the inter-tank space and the vacuum pump, a first exhaust valve provided in the first exhaust passage, the perlite replenishing container, and the Closing a second exhaust line connecting a vacuum pump, a second exhaust valve provided in the second exhaust line, the replenishment valve and the first exhaust valve, and opening the second exhaust valve, After forcibly exhausting the perlite replenishing container by operating the vacuum pump, the second exhaust valve is closed, and the replenishing valve and the first exhaust valve are opened to discharge the replenishing perlite into the inter-tank space. A controller for controlling operation of the refill valve, the first exhaust valve, the second exhaust valve, and the vacuum pump to supply.

According to the present invention, in a vacuum double-shell tank, it is possible to provide a technique for replenishing the space between the tanks with perlite while suppressing a decrease in the degree of vacuum in the space between the inner tank and the outer tank. .

FIG. 1 is a cross-sectional view showing the overall configuration of a vacuum double-shell tank according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view showing the overall configuration of a vacuum double-shell tank according to Modification 1 of the first embodiment. FIG. 3 is a cross-sectional view showing the overall configuration of a vacuum double-shell tank according to a second embodiment of the present invention. FIG. 4 is a flow chart showing the flow of automatic perlite replenishment processing.

[First Embodiment]
Next, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing the overall configuration of a vacuum double-shell tank 1A according to the first embodiment of the present invention.

A vacuum double-shell tank 1A shown in FIG. 1 is a tank for storing a cryogenic liquid 7 such as liquid hydrogen, liquid nitrogen, or liquefied natural gas. The vacuum double-shell tank 1A is installed on a hull, vehicle, ground, or the like while being supported by struts (not shown).

The vacuum double-shell tank 1A includes an inner tank 2, an outer tank 3 covering the inner tank 2, granular perlite 4 filled in a space 40 between the inner tank 2 and the outer tank 3, and a space 40 between the tanks. and a vacuum pump 6 connected to the

The inner tank 2 has a hollow spherical shell shape, and is formed by welding a number of SUS panels, for example. Inside the inner tank 2, a storage part 21 is formed for storing the low-temperature liquid 7 in a sealed state. The inner tank 2 can allow contraction deformation and deformation recovery due to the temperature difference between the normal temperature when the tank is constructed and the low temperature when the cryogenic liquid 7 is stored.

The outer tank 3 has a hollow spherical shell shape that is one size larger than the inner tank 2, and is formed by, for example, welding a large number of steel plates. The diameter of the outer tub 3 is larger than the diameter of the inner tub 2 . An empty inner tank 2 and an outer tank 3 are arranged concentrically, and the outer tank 3 covers the inner tank 2 at a predetermined interval (for example, about 1 to 2 m). The inner tub 2 is supported by the outer tub 3 by a rod or the like (not shown) connecting the outer wall of the inner tub 2 and the inner wall of the outer tub 3 .

The perlite 4 is packed in an inter-tank space 40 surrounded by the outer wall of the inner tank 2 and the inner wall of the outer tank 3 in a compacted state. The perlite 4 forms a heat insulating layer between the inner tank 2 and the outer tank 3 . Note that a known granular heat insulating material may be employed instead of the perlite 4 .

In the vacuum double-shell tank 1A having the above configuration, after the inner tank 2 and the outer tank 3 are completed, the inter-tank space 40 is filled with perlite 4 while the inner tank 2 is empty, and the inter-tank space is filled with perlite 4. The vacuum pump 6 is operated until 40 reaches a predetermined degree of vacuum. The degree of vacuum in the inter-tank space 40 is, for example, 0.1 to 1 Pa. When the cryogenic liquid 7 is supplied to the inner bath 2, the vacuum pump 6 is stopped. When the low-temperature liquid 7 is supplied to the inner tank 2, the cold heat of the low-temperature liquid 7 causes the inner tank 2 to shrink and deform, widening the gap between the inner tank 2 and the outer tank 3 and causing the perlite 4 to settle. As a result, a void in which no pearlite 4 exists is generated in the inter-tank space 40 at the top of the vacuum double-shell tank 1A. Such voids are also generated by an increase in the degree of compaction of the pearlite 4 due to aging. In this way, when a gap in which the perlite 4 does not exist is generated in the inter-tank space 40, the perlite 4 is replenished in the gap.

The perlite 4 (replenishing perlite) to be replenished in the inter-tank space 40 is enclosed in a perlite replenishing container 81 . The perlite replenishing container 81 is filled with replenishing perlite together with helium gas (or other inert gas). Furthermore, the internal pressure of the perlite replenishment container 81 is higher than the pressure of the inter-tank space 40 .

A perlite supply pipe 82 is provided at the top of the outer tank 3 . A pearlite supply pipe 82 penetrates the outer tank 3 , and one end of the pearlite supply pipe 82 opens into the inter-tank space 40 . The other end of the pearlite supply pipe 82 is connected to the pearlite replenishment container 81 via a vacuum pipe joint 83 .

A replenishment valve 84 is provided in the perlite supply pipe 82 . The replenishment valve 84 is a vacuum valve that switches between shutoff and connection of different pressure spaces between the inter-tank space 40 and the perlite replenishment container 81 .

As described above, the vacuum double-shell tank 1A according to the present embodiment has an inner tank 2 in which a storage part 21 for storing the cryogenic liquid 7 in a sealed state is formed, and the inner tank 2 is spaced apart by a predetermined distance. The outer tank 3 which is separated and covered, the granular perlite 4 filled in the vacuum inter-tank space 40 formed between the inner tank 2 and the outer tank 3, and the inter-tank space connected to the inter-tank space 40 and a vacuum pump 6 for forcibly evacuating 40 . Further, the vacuum double-shell tank 1A includes a perlite replenishing container 81 in which replenishing perlite is enclosed and whose internal pressure is higher than the inter-tank space 40, and a replenishment valve 84 provided in the perlite supply pipe 82 for switching between disconnection and connection between the inter-tank space 40 and the perlite replenishment container 81 .

In the vacuum double-shell tank 1A having the above structure, when a gap is formed in the inter-tank space 40 due to sedimentation of the perlite 4, the gap is replenished with the perlite 4. As shown in FIG. The perlite replenishment method at that time is to forcibly evacuate the inter-tank space 40, and remove the gaps generated by the sedimentation of the perlite 4 in the inter-tank space 40 and the perlite that is filled with the perlite for replenishment and has a higher pressure than the inter-tank space 40. Replenishing perlite is supplied to the inter-tank space 40 by communicating with the inside of the replenishing container 81 .

More specifically, while the inter-tank space 40 is forcibly evacuated by the vacuum pump 6, the replenishment valve 84 is switched so that the inter-tank space 40 and the inside of the perlite replenishing container 81 are connected, thereby replenishing the inter-tank space 40 with perlite. supply perlite for Operations of the vacuum pump 6 and the replenishment valve 84 may be manually operated by an operator. Alternatively, the vacuum double-shell tank 1A is provided with a control device 80 for controlling the operations of the vacuum pump 6 and the replenishment valve 84, and the control device 80 controls the vacuum pump 6 and the replenishment valve 84 so as to perform the above operations. good too.

In the vacuum double-shell tank 1A, when the space 40 between the inner tank 2 and the outer tank 3 communicates with the perlite replenishing container 81, the pressure difference between the inter-tank space 40 and the perlite replenishing container 81 causes The replenishing perlite in the perlite replenishing container 81 flows into the inter-tank space 40 . During this time, the inter-tank space 40 between the inner tank 2 and the outer tank 3 is forcibly evacuated, and the volume of the perlite replenishing container 81 is limited. can. Therefore, according to the vacuum double-shell tank 1A and the perlite replenishing method thereof, the perlite 4 is replenished in the inter-tank space 40 while suppressing a decrease in the degree of vacuum in the inter-tank space 40 between the inner tank 2 and the outer tank 3. can do.

Further, in the vacuum double-shell tank 1A and the pearlite replenishing method thereof according to the present embodiment, the perlite replenishing container 81 is filled with replenishing perlite together with helium gas.

The vacuum double-shell tank 1A is mainly used for storing cryogenic liquids such as liquefied hydrogen, but helium gas is suitable because it does not liquefy even when cryogenic liquids are stored in the inner tank 2.

Further, in the vacuum double-shell tank 1A according to this embodiment, the perlite replenishing container 81 is provided above the equator of the outer tank 3 .

As a result, compared with the case where the perlite replenishing container 81 is arranged on the side of the outer tank 3, the perlite supply pipe 82 can be shortened, and the quick discharge of replenishing perlite from the perlite replenishing container 81 can be promoted. . However, the position of the perlite replenishment container 81 is not limited to above the equator of the outer tank 3 , and may be provided on the side of the outer tank 3 .

Further, in the vacuum double-shell tank 1A according to the present embodiment, the pearlite replenishing container 81 is detachably connected to the pearlite supply pipe 82 and the vacuum pipe joint 83 .

As a result, the empty perlite replenishing container 81 can be removed from the perlite supply pipe 82 and another perlite replenishing container 81 filled with replenishing perlite can be connected to the perlite supply pipe 82 . In other words, the perlite replenishing container 81 can be of a replaceable cassette type. However, when the perlite replenishing container 81 is fixed to the upper portion of the outer tank 3 as shown in FIG. 2, the vacuum pipe joint 83 may be omitted.

[Second embodiment]
Next, a second embodiment of the invention will be described. FIG. 3 is a cross-sectional view showing the overall configuration of a vacuum double-shell tank 1B according to a second embodiment of the invention. In the vacuum double-shell tank 1B shown in FIG. 3, the vacuum double-shell tank 1B according to the first embodiment only has a structure for supplying replenishing perlite to the space 40 between the inner tank 2 and the outer tank 3. It differs from tank 1A. Therefore, in the following, a detailed description will be given of a configuration for supplying replenishing perlite to the gap portion of the space 40 between tanks. Therefore, detailed description is omitted.

A perlite hopper 91 is provided above the perlite replenishment container 81 . The replenishing perlite stored in the perlite hopper 91 is fed into the perlite replenishing container 81 through the feeding pipe 92 . An injection valve 93 is provided on the injection pipe 92 . This input valve 93 can switch between disconnection and connection between the perlite hopper 91 and the perlite replenishing container 81 .

The vacuum pump 6 is connected to the top of the outer tank 3 via a main exhaust pipe 98 . The main exhaust pipe 98 forms a first exhaust passage 98 a that connects the inter-tank space 40 and the vacuum pump 6 . The vacuum pump 6 can forcibly evacuate the space 40 between tanks from the top of the space 40 between tanks. The main exhaust pipe 98 is provided with a first exhaust valve 97 and a perlite collector 90 . The first exhaust valve 97 is a vacuum valve and can switch between disconnection and connection between the inter-tank space 40 and the vacuum pump 6 . The perlite collector 90 collects the perlite that has flowed into the main exhaust pipe 98 along with the exhaust from the inter-tank space 40 .

The vacuum pump 6 is also connected to the perlite replenishment container 81 via a main exhaust pipe 98 and an exhaust branch pipe 88 . More specifically, an exhaust branch pipe 88 connects the perlite replenishing container 81 and the downstream side of the first exhaust valve 97 of the main exhaust pipe 98 and the upstream side of the pearlite collector 90 . The exhaust branch pipe 88 and part of the main exhaust pipe 98 form a second exhaust passage 88a connecting the perlite replenishing container 81 and the vacuum pump 6 . A second exhaust valve 89 is provided in the exhaust branch pipe 88 . The second exhaust valve 89 is a vacuum valve and can switch between disconnection and connection between the inside of the pearlite replenishing container 81 and the vacuum pump 6 . The vacuum pump 6 may be connected to the perlite hopper 91 via an exhaust branch pipe (not shown) connected to the main exhaust pipe 98, similarly to the perlite replenishing container 81.

The outer tank 3 is provided with a level meter 94 for measuring the deposition level of the perlite 4 filled in the inter-tank space 40 . Further, the perlite replenishing container 81 is provided with a pressure gauge 95 for detecting the pressure inside the perlite replenishing container 81 . Further, the outer tank 3 is provided with a pressure gauge 96 for detecting the pressure in the inter-tank space 40 . The level gauge 94, the pressure gauge 95, and the pressure gauge 96 are communicably connected to the control device 80. FIG. The controller 80 operates the replenishment valve 84, the supply valve 93, the first exhaust valve 97, the second exhaust valve 89, and the vacuum pump 6 based on the detected values of the level gauge 94, the pressure gauge 95, and the pressure gauge 96. to control.

The control device 80 is a so-called computer, and has an arithmetic processing section such as a CPU, and a storage section such as a ROM and a RAM (none of which are shown). The storage unit stores programs executed by the arithmetic processing unit, various fixed data, and the like. The arithmetic processing unit transmits and receives data to and from an external device. In the control device 80, the arithmetic processing section reads and executes software such as a program stored in the storage section, thereby performing an automatic perlite replenishment process for replenishing the gaps of the inter-tank space 40 with the perlite 4.

Here, the flow of automatic perlite replenishment processing by the control device 80 will be described with reference to FIG. The control device 80 monitors the measured value of the level meter 94, and when the measured value of the level meter 94 (that is, the level of the perlite 4 in the inter-tank space 40) falls below a predetermined lower threshold (YES in step S1). , the process for replenishing the perlite 4 in the space 40 between tanks is started.

The controller 80 first closes the replenishment valve 84 and the first exhaust valve 97, and operates the vacuum pump 6 with the second exhaust valve 89 open (step S2). As a result, the inside of the perlite replenishment container 81 is forcibly exhausted. When the pressure detected by the pressure gauge 95 (that is, the internal pressure of the pearlite replenishing container 81) becomes equal to or lower than a predetermined pressure lower than the atmospheric pressure (YES in step S3), the control device 80 opens the injection valve 93 for a predetermined time. (Step S4). As a result, a predetermined amount of replenishing perlite is supplied from the perlite hopper 91 to the perlite replenishing container 81 .

Next, the controller 80 closes the injection valve 93 (step S5). When the pressure detected by the pressure gauge 95 (that is, the internal pressure of the perlite replenishing container 81) reaches a predetermined pressure higher than the pressure in the inter-tank space 40 and lower than the atmospheric pressure (YES in step S6), the controller 80 , the second exhaust valve 89 is closed and the first exhaust valve 97 is opened (step S7).

Subsequently, the controller 80 opens the replenishment valve 84 (step S8). As a result, the perlite for replenishment in the perlite replenishment container 81 is supplied to the gap portion of the inter-tank space 40 . After all the replenishing perlite in the perlite replenishing container 81 has been supplied to the inter-tank space 40, that is, after the perlite replenishing container 81 has become empty, the controller 80 determines that the measured value of the level meter 94 reaches the predetermined upper threshold value. (NO in step S9), the process returns to step S4 and repeats the process. On the other hand, when the measured value of the level meter 94 reaches a predetermined upper threshold value (YES in step S9), the controller 80 closes the replenishment valve 84 (step S10).

Finally, when the pressure in the inter-tank space 40 detected by the pressure gauge 96 reaches a predetermined set pressure (YES in step S11), the control device 80 stops the vacuum pump 6 and closes the first exhaust valve 97. (Step S12). Perlite 4 is automatically replenished into the inter-tank space 40 by the perlite automatic replenishment process described above.

As described above, the vacuum double-shell tank 1B according to the present embodiment has an inner tank 2 in which a storage part 21 for storing the cryogenic liquid 7 in a sealed state is formed, and the inner tank 2 is spaced apart by a predetermined distance. The outer tank 3 which is separated and covered, the granular perlite 4 filled in the vacuum inter-tank space 40 formed between the inner tank 2 and the outer tank 3, and the inter-tank space connected to the inter-tank space 40 40, a perlite replenishing container 81 in which replenishing perlite is enclosed and whose internal pressure is higher than that of the inter-tank space 40; and a replenishment valve 84 provided in the perlite supply pipe 82 for switching between disconnection and connection between the inter-tank space 40 and the perlite replenishment container 81 .

In the vacuum double-shell tank 1B, the vacuum pump 6 is connected to the perlite replenishment container 81, and the vacuum pump 6 makes the inside of the perlite replenishment container 81 higher than the inter-tank space 40 and lower than the atmospheric pressure. forced to exhaust. As a result, the inside of the perlite replenishing container 81 has a lower pressure than the inter-tank space 40 .

While the inter-tank space 40 is forcibly evacuated by the vacuum pump 6, the replenishing perlite is supplied to the inter-tank space 40 by switching the replenishing valve 84 so that the inter-tank space 40 and the perlite replenishing container 81 are connected. be done.

Furthermore, since the pump for evacuating the perlite replenishing container 81 and the vacuum pump 6 for evacuating the inter-tank space 40 are shared, the number of components of the vacuum double-shell tank 1B can be reduced.

Further, the vacuum double-shell tank 1B according to the present embodiment includes a first exhaust path 98a connecting the inter-tank space 40 and the vacuum pump 6, a first exhaust valve 97 provided in the first exhaust path 98a, A second exhaust line 88a connecting the perlite replenishing container 81 and the vacuum pump 6, a second exhaust valve 89 provided in the second exhaust line 88a, and a control device 80 are further provided. Then, the control device 80 closes the replenishment valve 84 and the first exhaust valve 97, opens the second exhaust valve 89, and operates the vacuum pump 6 to forcibly exhaust the perlite replenishment container 81. The replenishment valve 84, the first exhaust valve 97, the second exhaust valve 89, the replenishment valve 84, the first exhaust valve 97, the second exhaust valve 89, and the operation of the vacuum pump 6.

As a result, the replenishing perlite can be automatically supplied to the inter-tank space 40 of the vacuum double-shell tank 1B.

Although the preferred embodiments of the present invention have been described above, the present invention may include modifications of the details of the specific structures and/or functions of the above embodiments without departing from the spirit of the present invention. .

1A, 1B: Vacuum double-shell tank 2: Inner tank 3: Outer tank 4: Perlite 6: Vacuum pump 7: Cryogenic liquid 21: Storage part 40: Space between tanks 80: Controller 81: Perlite replenishment container 82: Perlite supply Pipe 83 : Vacuum pipe joint 84 : Replenishment valve 88 : Exhaust branch pipe 88a : Second exhaust passage 89 : Exhaust valve 90 : Pearlite collector 91 : Perlite hopper 92 : Input pipe 93 : Input valve 94 : Level gauges 95, 96 : Pressure gauge 97: Exhaust valve 98: Main exhaust pipe 98a: First exhaust passage

Claims (7)

An inner tank that stores a liquid in a sealed state, an outer tank that covers the inner tank at a predetermined interval, and granular perlite filled in a space between the inner tank and the outer tank, A perlite replenishment method for a vacuum double-shell tank, wherein the inter-tank space is a vacuum,
While forcibly exhausting the inter-tank space, the inter-tank space is communicated with a perlite replenishment container in which replenishing perlite is sealed together with helium gas and has a higher pressure than the inter-tank space. supplying the supplemental perlite;
Perlite replenishment method for vacuum double-shell tank. An inner tank that stores a liquid in a sealed state, an outer tank that covers the inner tank at a predetermined interval, and granular perlite filled in a space between the inner tank and the outer tank, A perlite replenishment method for a vacuum double-shell tank, wherein the inter-tank space is a vacuum,
While forcibly exhausting the inter-tank space, the inter-tank space is communicated with a perlite replenishing container in which replenishing perlite is enclosed and which has a higher pressure than the inter-tank space and a lower pressure than the atmospheric pressure , supplying the replenishing perlite to the inter-tank space;
Perlite replenishment method for vacuum double-shell tank. an inner tank in which a reservoir for storing liquid in a sealed state is formed;
an outer tank covering the inner tank with a predetermined interval;
Granular perlite filled in a vacuum inter-tank space formed between the inner tank and the outer tank;
a vacuum pump connected to the inter-tank space and forcibly exhausting the inter-tank space;
a perlite replenishing container in which replenishing perlite is sealed together with helium gas and whose internal pressure is higher than the inter-tank space;
a perlite supply pipe that penetrates the top of the outer tank and connects the space between the tanks and the inside of the perlite replenishment container;
a replenishment valve provided in the perlite supply pipe for switching between disconnection and connection between the inter-tank space and the interior of the perlite replenishment container;
While the inter-tank space is forcibly evacuated by the vacuum pump, the replenishing perlite is supplied to the inter-tank space by switching the replenishing valve so that the inter-tank space and the inside of the perlite replenishing container are connected. do,
Vacuum double shell tank. The perlite replenishment container is provided above the equator of the outer tank,
Vacuum double-shell tank according to claim 3 . The perlite replenishment container is detachably connected to the perlite supply pipe by a joint,
A vacuum double-shell tank according to claim 3 or 4 . an inner tank in which a reservoir for storing liquid in a sealed state is formed;
an outer tank covering the inner tank with a predetermined interval;
Granular perlite filled in a vacuum inter-tank space formed between the inner tank and the outer tank;
a perlite replenishing container in which replenishing perlite is enclosed;
a perlite supply pipe that penetrates the top of the outer tank and connects the space between the tanks and the inside of the perlite replenishment container;
a replenishment valve provided in the perlite supply pipe for switching between disconnection and connection between the inter-tank space and the inside of the perlite replenishment container;
a vacuum pump capable of switching between disconnection and connection with the perlite replenishing container and the inter-tank space,
The vacuum pump is connected to the perlite replenishing container , and after the vacuum pump forces the inside of the perlite replenishing container to be evacuated to a pressure higher than the space between the tanks and lower than the atmospheric pressure, the vacuum pump is connected to the tank. By switching the replenishment valve so that the inter-vessel space and the inside of the perlite replenishing container are connected while forcibly exhausting the inter-vessel space with the vacuum pump, the supplemental perlite is supplied ;
Vacuum double shell tank. a first exhaust path connecting the inter-tank space and the vacuum pump;
a first exhaust valve provided in the first exhaust passage;
a second exhaust path connecting the perlite replenishing container and the vacuum pump;
a second exhaust valve provided in the second exhaust passage;
closing the replenishment valve and the first exhaust valve, opening the second exhaust valve, and operating the vacuum pump to forcibly exhaust the perlite replenishing container, and then closing the second exhaust valve; Operation of the replenishment valve, the first exhaust valve, the second exhaust valve, and the vacuum pump so as to open the replenishment valve and the first exhaust valve to supply the replenishing perlite to the inter-tank space. and a control device that controls the
Vacuum double-shell tank according to claim 6 .

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