JP6928486B2 - Outgassing system - Google Patents

Description

The present invention relates to an outgassing system that releases hydrogen gas generated in a tank that stores liquid hydrogen to the atmosphere.

In the tank for storing liquid hydrogen, the stored liquid hydrogen is vaporized by heat input from the outside to generate hydrogen gas (hereinafter, also referred to as "evaporative gas"). When the evaporative gas accumulates in the upper part of the tank, the pressure inside the tank rises, so it is necessary to appropriately discharge the evaporative gas from the tank.

For example, Patent Document 1 discloses a liquid hydrogen storage device that is also used as a hydrogen station for supplying liquefied hydrogen. This liquid hydrogen storage device includes a liquid hydrogen storage tank, a discharge pipe connected to the liquid hydrogen storage tank, and a safety valve provided in the discharge pipe. When the pressure in the tank exceeds a predetermined pressure due to the evaporative gas accumulated in the tank, the safety valve opens and the evaporative gas is discharged to the outside through the discharge pipe. Patent Document 1 describes that the evaporative gas is converted into water and then discharged.

JP-A-2009-127632

Instead of discharging the evaporative gas in the tank as water, it is conceivable to install a discharge tower that releases the evaporative gas to the atmosphere as it is at a position higher than the tank. However, since the temperature of the evaporative gas generated in the tank is extremely low, when the discharge tower is a general pipe, the air may be cooled and liquid air may be generated around the discharge tower. When extremely low temperature liquid air is generated, it is desirable to suppress the generation of liquid air because it is necessary to take measures such as making the discharge tower low temperature resistant.

Therefore, an object of the present invention is to provide an outgassing system capable of suppressing the generation of liquid air around a discharge tower that discharges evaporative gas generated in a tank.

In order to solve the above problems, the gas discharge system according to the present invention is provided with a tank for storing liquid hydrogen and a discharge tower extending upward, at least at the upper end thereof, provided with a discharge port open to the atmosphere. A discharge tower having a double-tube structure consisting of an inner pipe and an outer pipe that covers the inner pipe with a gap between the inner pipe and the evaporative gas vaporized by the liquid hydrogen in the tank. Is provided with a discharge line that guides the gas into the inner pipe, and a gas supply device that supplies a mediator gas that is hydrogen gas or helium gas having a temperature higher than the boiling point of oxygen in the gap between the inner pipe and the outer pipe. ..

According to the above configuration, a gas having a temperature higher than the boiling point of oxygen is supplied to the gap between the inner pipe and the outer pipe, so that liquid air is generated around the portion of the double pipe structure in the discharge tower. Can be suppressed. Further, since the intermediary gas such as hydrogen gas or helium gas is supplied to the gap between the inner pipe and the outer pipe, it is possible to suppress the generation of liquid air in the gap.

In the outgassing system, the outgassing tower discharges the mediator gas in the same direction as the evaporative gas is discharged from the outgassing port, so that the inner pipe and the outer pipe are discharged around the outgassing port. It may be configured to open the gap between the spaces to the atmosphere. According to this configuration, the evaporative gas discharged from the discharge port is shielded by the intermediary gas discharged around the discharge port in the same direction as the evaporative gas is discharged. Therefore, it is possible to suppress the generation of liquid air in the vicinity of the discharge port.

In the outgassing system, the gas supply device includes a heater, a first supply line that supplies the vaporized gas or the liquid hydrogen from the tank to the heater, and the inner tube and the outside from the heater. A second supply line that supplies the intermediary gas to the gap between the pipes may be provided. According to this configuration, since the evaporated gas in the tank or the liquid hydrogen stored in the tank is used as the intermediary gas to be supplied to the gap between the inner pipe and the outer pipe, the gas supply device can be realized with a simple configuration.

The gas release system includes an on-off valve provided in the release line, and the gas supply device starts supplying the intermediary gas when the pressure in the tank exceeds the first set pressure. The on-off valve is closed when the pressure in the tank is equal to or lower than the second set pressure higher than the first set pressure, and opens when the pressure in the tank exceeds the second set pressure. May be good. According to this configuration, the mediator gas is started to be supplied to the gap between the inner pipe and the outer pipe before the evaporative gas is guided into the inner pipe. Therefore, even when the evaporative gas is started to be guided into the inner pipe, liquid air is surely applied. Can be suppressed.

According to the present invention, it is possible to provide an outgassing system capable of suppressing the generation of liquid air around a discharge tower that discharges evaporative gas generated in a tank.

(A) is a schematic side view of a liquid hydrogen carrier provided with an outgassing system according to an embodiment of the present invention, and (B) is a schematic plan view of the liquid hydrogen carrier shown in (A). It is a schematic block diagram of the gas release system included in the liquid hydrogen carrier shown in FIG. (A) is a schematic side view of the liquid hydrogen carrier according to the modified example, and (B) is a schematic side view of the liquid hydrogen carrier shown in (A).

Hereinafter, an outgassing system according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 (A) is a schematic side view of a liquid hydrogen carrier 1 provided with an outgassing system according to an embodiment, and FIG. 1 (B) is a schematic plan view of the liquid hydrogen carrier 1. As shown by the broken line in FIG. 1, the hull 2 of the liquid hydrogen carrier 1 is provided with a tank 3 for storing liquid hydrogen in which hydrogen gas is liquefied.

The upper portion of the tank 3 projects upward from the upper deck 2a of the hull 2 and is covered with the tank cover 2b provided on the upper deck 2a. In the drawing, only one tank 3 provided on the hull 2 is shown, but a plurality of tanks 3 may be provided on the hull 2 so as to be arranged in the direction of the captain, for example. As shown in FIG. 1, a bridge 4 for maneuvering the ship during the voyage is provided at the rear part of the upper deck 2a in the captain direction.

Further, at the central portion of the upper deck 2a in the captain direction, a discharge tower 5 extending upward from the upper deck 2a is provided. The discharge tower 5 releases the evaporated gas vaporized by liquid hydrogen in the tank 3 to the atmosphere. In the present embodiment, the discharge tower 5 has a substantially I-shape extending in the vertical direction, and a discharge port 6 open to the atmosphere upward is provided at the upper end of the discharge tower 5. The evaporative gas guided from the tank 3 to the lower end of the discharge tower 5 rises in the discharge tower 5 and is discharged from the discharge port 6.

FIG. 2 is a schematic configuration diagram of an outgassing system 10 included in the liquid hydrogen carrier 1. In the unlikely event that the pressure in the tank 3 exceeds the preset allowable pressure Pa (“second set pressure” of the present invention) due to the evaporative gas generated in the tank 3, the outgassing system 10 is the tank 3 It is a system that releases the excess evaporative gas inside to the atmosphere through the discharge tower 5. In FIG. 2, for the sake of simplification of the figure, the entire discharge tower 5 is not shown, and only the upper end portion of the discharge tower 5 is shown.

The gas discharge system 10 includes the tank 3 and the discharge tower 5 described above, a discharge line 11 for guiding the vaporized gas vaporized by liquid hydrogen from the tank 3 to the discharge tower 5, and a first on-off valve provided in the discharge line 11. A pressure gauge 13 for measuring the pressure P in the tank 3 and a control device 14 for controlling the first on-off valve 12 are provided.

The pressure value measured by the pressure gauge 13 is sent to the control device 14. The control device 14 opens and closes the first on-off valve 12 according to the pressure value received from the pressure gauge 13. Specifically, when the pressure P measured by the pressure gauge 13 is equal to or less than the allowable pressure Pa, the first on-off valve 12 is in a closed state. When the pressure P measured by the pressure gauge 13 exceeds the allowable pressure Pa, the control device 14 opens the first on-off valve 12. As a result, the evaporative gas in the tank 3 is guided to the discharge tower 5 through the discharge line 11, and the pressure in the tank 3 is lowered.

As a result of opening the first on-off valve 12, when the pressure P measured by the pressure gauge 13 falls below a predetermined pressure of the allowable pressure Pa or lower, the control device 14 closes the first on-off valve 12.

However, the first on-off valve 12 does not have to be an electric valve, and may be a mechanical valve. For example, the first on-off valve 12 may be a spring-type safety valve that permits distribution when the pressure P in the tank 3 exceeds the allowable pressure Pa.

In the present embodiment, the discharge tower 5 has a double pipe structure including an inner pipe 7 and an outer pipe 8 surrounding the inner pipe 7 from the upper end to the lower end. The above-mentioned discharge port 6 is provided at the upper end of the inner pipe 7. The evaporative gas guided from the tank 3 to the lower end of the inner pipe 7 through the discharge line 11 rises in the inner pipe 7 and is discharged from the discharge port 6. The outer pipe 8 is provided with a gap C between the outer pipe 8 and the inner pipe 7. Further, the upper end portion of the discharge tower 5 is provided with an annular opening 9 formed by the upper end portion of the outer pipe 8 and the upper end portion of the inner pipe 7. The opening 9 opens to the atmosphere in the same direction as the discharge port 6.

Further, the gas discharge system 10 includes a gas supply device 20 that supplies hydrogen gas at room temperature to the gap C between the inner pipe 7 and the outer pipe 8. The gas supply device 20 is a device for suppressing liquefaction of oxygen and nitrogen around the outer pipe 8.

That is, since the boiling point of hydrogen is about -253 ° C, the temperature of the evaporative gas guided to the discharge tower 5 through the discharge line 11 is the boiling point of nitrogen (about -196 ° C), the boiling point of oxygen (about -183 ° C), and the like. May be lower. In this case, the cryogenic evaporative gas may flow through the discharge tower or be discharged from the discharge tower, so that the air may be cooled and liquid air may be generated around the discharge tower. However, in the present embodiment, the gas supply device 20 supplies hydrogen gas at room temperature, which is a temperature higher than the boiling point of oxygen, around the inner pipe 7 that discharges the evaporative gas into the atmosphere. The generation of liquid air is suppressed.

In the present embodiment, the gas supply device 20 includes a heater 21, a first supply line 22 that supplies evaporation gas from the tank 3 to the heater 21, and a gap between the heater 21 and the inner pipe 7 and the outer pipe 8. A second supply line 23 for supplying hydrogen gas to C is provided.

As the heater 21 of the gas supply device 20, for example, it is desirable to use a warm-up heater for heating the tank 3 when the tank 3 is empty, from the viewpoint of simplifying the entire system.

In the present embodiment, one end of the first supply line 22 is connected to the upper part of the tank 3, and the other end of the first supply line 22 is connected to the inlet of the heater 21. Further, one end of the second supply line 23 is connected to the outlet of the heater 21, and the other end of the second supply line 23 is the lower end of the discharge tower 5, specifically, the lower end of the inner pipe 7 and the outer pipe. It is connected between the lower ends of 8.

The first supply line 22 is provided with a second on-off valve 24. When the second on-off valve 24 is open, evaporative gas is guided from the tank 3 to the heater 21 through the first supply line 22. The heater 21 heats the guided evaporative gas to raise the temperature of the evaporative gas. The evaporative gas whose temperature has risen is guided to the gap C of the discharge tower 5 through the second supply line 23. Hereinafter, the evaporative gas guided to the gap C between the inner pipe 7 and the outer pipe 8 by the gas supply device 20 is referred to as a “mediator gas” in order to distinguish it from the evaporative gas guided into the inner pipe 7 through the discharge line 11. ..

The gas supply device 20 is controlled by the control device 14. That is, the control device 14 controls the opening / closing of the second on-off valve 24 in the gas supply device 20 and the start / stop of the operation of the heater 21. However, the second on-off valve 24 does not have to be an electric valve controlled by the control device 14, but may be a mechanical valve.

Next, the operation of the gas release system 10 when the gas pressure in the tank 3 rises will be described.

The control device 14 stores in advance set pressures (“first set pressure”) Ps lower than the permissible pressure Pa. The control device 14 causes the gas supply device 20 to start supplying the intermediary gas when the pressure P measured by the pressure gauge 13 exceeds the set pressure Ps.

Specifically, when the pressure measured by the pressure gauge 13 exceeds the set pressure Ps, the control device 14 starts the operation of the heater 21 and opens the second on-off valve 24. As a result, the intermediary gas heated by the heater 21 is supplied to the gap C between the inner pipe 7 and the outer pipe 8. The intermediary gas supplied to the gap C between the inner pipe 7 and the outer pipe 8 rises from the lower end of the discharge tower 5, and is discharged to the atmosphere through the opening 9 at the upper end of the discharge tower 5.

When the pressure P measured by the pressure gauge 13 exceeds the permissible pressure Pa as a result of the pressure in the tank 3 further increasing, the control device 14 opens the first on-off valve 12. As a result, the evaporative gas is supplied from the tank 3 into the inner pipe 7 through the discharge line 11. The evaporative gas supplied into the inner pipe 7 rises from the lower end of the discharge tower 5, and is discharged to the atmosphere from the discharge port 6 at the upper end of the discharge tower 5.

As described above, in the present embodiment, the gas supply device 20 is referred to the inner pipe 7 before the pressure in the tank 3 exceeds the permissible pressure Pa, in other words, before the evaporative gas is guided into the inner pipe 7 through the discharge line 11. The intermediary gas is started to be supplied to the gap C between the outer pipes 8. Therefore, the generation of liquid air can be reliably suppressed even when the evaporative gas is started to be guided into the inner pipe 7.

However, the timing at which the second on-off valve 24 is opened may be the same as the timing at which the first on-off valve 12 is opened. Further, the pressure in the tank 3 as a reference for opening the first on-off valve 12 does not have to be the permissible pressure Pa, and may be lower than the permissible pressure Pa, for example. In the present specification, the allowable pressure Pa means the upper limit pressure allowed as the gas pressure in the tank 3 or the pressure in the vicinity thereof.

Since the inner pipe 7 through which the cryogenic evaporative gas flows is covered with the intermediary gas supplied by the gas supply device 20, it is suppressed that the air around the discharge tower 5 touches the inner pipe 7 and is cooled. Further, since the opening 9 surrounding the discharge port 6 opens to the atmosphere in the same direction as the discharge port 6, the intermediary gas is discharged from the opening 9 in the same direction as the evaporative gas discharged from the discharge port 6. Will be done. Therefore, the evaporative gas discharged from the discharge port 6 is shielded by the intermediary gas discharged from the opening 9. Therefore, it is possible to suppress the generation of liquid air in the vicinity of the discharge port 6.

The temperature of the intermediary gas is lowered by being cooled by the evaporative gas rising in the inner pipe 7 as the discharge tower 5 is raised. In the present embodiment, the temperature of the intermediary gas emitted from the outlet of the heater 21 is such that the temperature of the intermediary gas when rising in the discharge tower 5 and reaching the opening 9 (when being discharged from the gap C) is oxygen. It is set so that it does not fall below the boiling point.

As described above, in the gas discharge system 10 of the present embodiment, the gas having a temperature higher than the boiling point of oxygen is supplied to the gap C between the inner pipe 7 and the outer pipe 8, so that the gas having a temperature higher than the boiling point of oxygen is supplied around the discharge tower 5. It is possible to suppress the generation of liquid air.

Further, since hydrogen gas as an intermediary gas is supplied to the gap C between the inner pipe 7 and the outer pipe 8, the generation of liquid air in the gap C can also be suppressed.

Further, in the present embodiment, since the evaporative gas in the tank is used as the intermediary gas to be supplied to the gap between the inner pipe 7 and the outer pipe 8, the gas supply device 20 can be realized with a simple configuration.

The present invention is not limited to the above embodiment, and various modifications can be made without departing from the gist of the present invention.

For example, the shape and arrangement of the tank 3 and the discharge tower 5 are not limited to those shown in the above embodiment. For example, in the above embodiment, the discharge tower 5 has a substantially I-shape extending in the vertical direction, but as shown in FIG. 3, the discharge tower 5 has a substantially Y-shape branched in the middle extending upward from the upper deck 2a. May be formed in. Specifically, the discharge tower 5 shown in FIG. 3 has an extension portion 5a extending upward from the upper deck 2a and two branch portions 5b branching from the upper end of the extension portion 5a to both sides in the ship width direction and extending diagonally upward. Has. A discharge port 6 opened to the atmosphere is provided at the upper end of each branch portion 5b, and the evaporated gas rising in the inner pipe 7 of the discharge tower 5 is discharged to the atmosphere from each discharge port 6.

Further, in the above embodiment, hydrogen gas at room temperature is supplied as a mediator gas to the gap C between the inner pipe 7 and the outer pipe 8, but the temperature of the mediator gas supplied to the gap C does not have to be normal temperature. Well, the temperature may be higher than the boiling point of oxygen. Further, the intermediary gas does not have to be hydrogen gas, and may be helium gas having a boiling point lower than that of oxygen.

Further, in the above embodiment, the discharge tower 5 has a double pipe structure from the lower end to the upper end thereof, but the discharge tower 5 may have a double pipe structure only at the upper end portion thereof. In this case, it is possible to suppress the generation of liquid air around the portion of the double pipe structure in the discharge tower 5.

Further, in the above embodiment, the discharge tower 5 is configured to discharge the intermediary gas from the gap C in the same direction as the evaporative gas is discharged from the discharge port 6, but the discharge tower 5 is the discharge port. It may be configured to discharge the intermediary gas from the gap C in a direction different from the direction in which the evaporative gas is discharged from 6 (for example, inward or outward in the radial direction of the discharge tower 5).

Further, in the above embodiment, the discharge tower 5 has an opening 9 around the discharge port 6 that opens a gap C between the inner pipe 7 and the outer pipe 8 to the atmosphere. It does not have to have an opening that opens the gap C to the atmosphere. In this case, the intermediary gas that has risen to the upper end of the discharge tower 5 may be returned to the gas supply device 20 through a pipe separately provided in the discharge tower 5.

Further, in the above embodiment, the first supply line 22 supplies the evaporative gas from the tank 3 to the heater 21, but the first supply line 22 may supply liquid hydrogen from the tank 3 to the heater 21. In this case, the heater 21 includes a vaporizer for vaporizing liquid hydrogen and a heater for raising the temperature of the gas generated by the vaporizer.

Further, the gas supply device 20 used the evaporative gas in the tank 3 by heating it as the mediation gas to be supplied to the gap C of the discharge tower 5, but the gas supply device 20 mediates from another tank or device provided in the liquid hydrogen carrier 1. Gas may be supplied to the gap C of the discharge tower 5.

Further, the outgassing system according to the present invention is not limited to the one applied to the liquid hydrogen carrier, and can be applied to the land equipment. That is, the outgassing system's tanks and outgassing towers may be installed on land. When the gas release system according to the present invention is applied to onshore equipment, the gas release system may include a gas tank for storing an intermediary gas as a part of a gas supply device in addition to a tank for storing liquid hydrogen. It may be supplied from the gas tank to the gap between the inner pipe and the outer pipe of the discharge tower. This gas tank may be, for example, a buffer tank for storing evaporative gas generated in a tank for storing liquid hydrogen.

1: Liquid hydrogen carrier 3: Tank 5: Discharge tower 6: Discharge port 7: Inner pipe 8: Outer pipe 10: Gas release system 11: Discharge line 12: First on-off valve (on-off valve)
13: Pressure gauge 14: Control device 20: Gas supply device 21: Heater 22: First supply line 23: Second supply line C: Gap Pa: Allowable pressure (second set pressure)
Ps: Set pressure (first set pressure)

Claims (4)

An outgassing system installed on the hull or land equipment.
A tank for storing liquid hydrogen and
An inner pipe that extends upward and has a discharge port open to the atmosphere at least at the upper end thereof, and an outer pipe that covers the circumference of the inner pipe with a gap between the inner pipe and the inner pipe. A discharge tower with a double-tube structure consisting of
A discharge line that guides the vaporized gas vaporized by the liquid hydrogen into the inner pipe in the tank, and
A gas release system comprising a gas supply device for supplying an intermediary gas such as hydrogen gas or helium gas having a temperature higher than the boiling point of oxygen in the gap between the inner pipe and the outer pipe. The discharge tower creates the gap between the inner pipe and the outer pipe around the discharge port so as to discharge the mediator gas in the same direction as the evaporative gas is discharged from the discharge port to the atmosphere. The gas release system according to claim 1, which is configured to open to. The gas supply device is provided in the heater, the first supply line for supplying the evaporative gas or the liquid hydrogen from the tank to the heater, and the gap between the heater and the inner pipe and the outer pipe. The gas release system according to claim 1 or 2, comprising a second supply line for supplying the intermediary gas. The on-off valve provided in the discharge line is provided.
The gas supply device starts supplying the intermediary gas when the pressure in the tank exceeds the first set pressure, and the on-off valve has a pressure in the tank higher than the first set pressure. The gas release system according to any one of claims 1 to 3, which is closed when the pressure is equal to or lower than the second set pressure and opens when the pressure in the tank exceeds the second set pressure.

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