Liquid hydrogen storage device

Abstract

To reduce a heat input amount into a hydrogen tank from a port and improve heat insulation performance of a hydrogen tank.SOLUTION: A liquid hydrogen storage device 100 includes: a hydrogen tank 10 installed inside a vehicle 200 to store liquid hydrogen; and a boil off-line 40 connected to the hydrogen tank 10 to discharge a hydrogen gas vaporized inside the hydrogen tank 10 to the outside of the vehicle 200. The hydrogen tank 10 includes a pump port 20 projecting from an outside surface. The boil off-line 40 is disposed so as to surround the pump port 20.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to the structure of a liquid hydrogen storage device. [Background technology]

[0002] Patent Document 1 discloses a liquid hydrogen storage system that includes a hydrogen tank for storing liquid hydrogen and a pipe for releasing hydrogen gas from the hydrogen tank. The liquid hydrogen stored in the hydrogen tank is partially vaporized by natural heat input from the outside air. The vaporized hydrogen gas is released to the outside through the pipe. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2024-6562 Summary of the Invention [Problem to be solved by the invention]

[0004] Hydrogen tanks that store cryogenic liquid hydrogen are equipped with multiple ports, including ports for attaching equipment to be installed inside the hydrogen tank and ports for connecting piping for injecting liquid hydrogen. Hydrogen tanks that store cryogenic liquid hydrogen are insulated, but these ports may not be sufficiently insulated in order to allow for the removal of equipment and piping. In such cases, heat input from the ports may increase the amount of vaporization of liquid hydrogen inside the hydrogen tank.

[0005] Therefore, an object of the present disclosure is to reduce the amount of heat input from the port into the interior of the hydrogen tank and improve the thermal insulation performance of the hydrogen tank. [Means for solving the problem]

[0006] The liquid hydrogen storage device of the present disclosure is a liquid hydrogen storage device that is mounted within a vehicle and includes a hydrogen tank that stores liquid hydrogen, and a boil-off line that is connected to the hydrogen tank and releases hydrogen gas vaporized within the hydrogen tank to the outside of the vehicle, wherein the hydrogen tank has at least one port protruding from its outer surface, and the boil-off line is arranged to surround at least one of the ports. [Effects of the Invention]

[0007] The port is cooled by the low-temperature hydrogen gas vaporized inside the hydrogen tank, known as boil-off gas, which reduces the amount of heat input from the port into the hydrogen tank, improving the insulating performance of the hydrogen tank. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic cross-sectional view of a liquid hydrogen storage device according to an embodiment. [Figure 2] 2 is a plan view of the liquid hydrogen storage device according to the embodiment, taken along the line AA in FIG. 1. [Figure 3] 3 is a cross-sectional view showing the configuration of a pump port and a boil-off line of the liquid hydrogen storage device of the embodiment, taken along the line BB shown in FIG. 2. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] A liquid hydrogen storage device 100 according to an embodiment will now be described. As shown in Fig. 1, the liquid hydrogen storage device 100 is mounted on a vehicle 200 and stores hydrogen in a liquid state. In this case, the vehicle 200 is a vehicle that uses hydrogen as one of its energy sources, such as a fuel cell vehicle or a hydrogen engine vehicle. The following description will take as an example a liquid hydrogen storage device 100 suitable for a hydrogen engine vehicle equipped with a direct injection hydrogen engine (not shown) that directly injects hydrogen gas into the engine cylinder.

[0010] The liquid hydrogen storage device 100 includes a hydrogen tank 10, a hydrogen pump 30, and a boil-off line 40. The hydrogen tank 10 includes a tank body 11, a collector 12, a liquid hydrogen filling port 13, a hydrogen gas return port 14, a boil-off gas port 15, and a pump port 20.

[0011] Tank body 11 stores liquid hydrogen in an insulated manner. Tank body 11 can be, for example, a container with a double-tube structure in which an inner tank made of stainless steel and an outer tank covering the inner tank are separated by a vacuum insulation layer. Hydrogen tank 10 is also shaped like a rice bag or sphere to maintain uniform pressure on the inner wall.

[0012] The liquid hydrogen filling port 13 is attached to the side of the upper part of the tank body 11 and is a port that receives a supply of liquid hydrogen from the outside. The hydrogen gas return port 14 is attached to the side of the upper part of the tank body 11 and is a port that draws in hydrogen gas that has evaporated due to natural heat input when filling with liquid hydrogen (so-called boil-off gas) from the outside and releases it to the outside.

[0013] In order to properly suck in the boil-off gas, the liquid hydrogen level when the tank is fully filled is lower than this hydrogen gas return port 14. Therefore, the internal volume of the hydrogen tank 10 is larger than the volume of liquid hydrogen when the tank is fully filled. As a result, a space of a predetermined volume or more (hereinafter referred to as the "upper space") always exists above the hydrogen tank 10. This upper space is where hydrogen gas generated by the vaporization of the liquid hydrogen stored in the tank accumulates. For this reason, a boil-off gas port 15 is provided near the top of the tank body 11, i.e., near the upper end of the tank body 11 in the direction of gravity, to discharge the boil-off gas that has accumulated above the tank body 11.

[0014] The pump port 20 is a port to which a hydrogen pump 30 is attached. The pump port 20 includes a nozzle 21 protruding from the tank body 11 and a flange 22 attached to the upper end of the nozzle 21.

[0015] Here, the hydrogen pump 30 is a booster pump that pumps up the liquid hydrogen stored in the hydrogen tank 10 and sends it to the hydrogen engine. The liquid hydrogen pressurized by the pump is vaporized in a vaporizer (not shown) to become high-pressure hydrogen gas. The high-pressure hydrogen gas is then supplied to the hydrogen engine.

[0016] Here, the hydrogen pump 30 is composed of a drive unit 31, a mounting flange 32, a shaft unit 34, and a pump unit 35. The pump unit 35 houses a pump body that pressurizes liquid hydrogen. The shaft unit 34 houses a drive shaft that connects the drive unit 31 and the pump unit 35. The shaft unit 34 is connected to the drive unit 31. The mounting flange 32 is connected to the lower end of the drive unit 31. The mounting flange 32 is fastened to the flange 22 of the pump port 20 to fix the drive unit 31 to the tank body 11.

[0017] Collector 12 is disposed on the bottom surface of tank body 11 and is a portion that is recessed from the surrounding area. Collector 12 houses pump unit 35 inside. Even when the remaining amount of liquid hydrogen is low, collector 12 can position pump unit 35 in the liquid, allowing it to pump up all the liquid hydrogen to the last drop.

[0018] The boil-off line 40 is connected to the boil-off gas port 15 and releases the hydrogen gas (boil-off gas) vaporized in the hydrogen tank 10 outside the vehicle 200. An electromagnetic safety valve 50 and a reactor 60 are connected to the boil-off line 40. The electromagnetic safety valve 50 opens when the pressure in the hydrogen tank 10 exceeds a predetermined threshold. The reactor 60 also uses a catalyst to react the hydrogen gas with air to convert it into water, which is then released outside the vehicle 200.

[0019] 2 and 3, the boil-off line 40 is disposed so as to surround the nozzle 21 and to be in contact with the lower surface of the flange 22. The boil-off line 40 is attached to the lower surface of the flange 22 by a fixing member 25.

[0020] The configuration of the boil-off line 40 and the configuration of the fixing member 25 will be described below.

[0021] As shown in FIG. 2, the boil-off line 40 includes a boil-off gas port connecting pipe 41, an upstream T-piece 42, one side cooling pipe 43, the other side cooling pipe 44, a downstream T-piece 45, and a discharge pipe 46.

[0022] The upstream T-piece 42 is connected to the boil-off gas port connecting pipe 41, one-side cooling pipe 43, and the other-side cooling pipe 44, and branches the hydrogen gas flowing in from the boil-off gas port connecting pipe 41 into the one-side cooling pipe 43 and the other-side cooling pipe 44. The downstream T-piece 45 is connected to the one-side cooling pipe 43, the other-side cooling pipe 44, and a discharge pipe 46, and merges the hydrogen gas flowing in from the one-side cooling pipe 43 and the other-side cooling pipe 44 into the discharge pipe 46.

[0023] The one-side cooling pipe 43 surrounds the outer periphery of one side of the nozzle 21 while bending back and forth between the outer periphery and the inner periphery of the flange 22. Similarly, the other-side cooling pipe 44 surrounds the outer periphery of the other side of the nozzle 21 while bending back and forth between the outer periphery and the inner periphery of the flange 22. The one-side cooling pipe 43 and the other-side cooling pipe 44 are connected by an upstream T-piece 42 and a downstream T-piece 45 and are configured to surround the outer periphery of the nozzle 21.

[0024] 3, one cooling pipe 43 and the other cooling pipe 44 are attached to the lower surface of flange 22 by fixing members 25 so as to be in contact with the lower surface of flange 22. Fixing members 25 are made up of upper member 26, lower member 27, bolts 28A, and nuts 28B. Upper member 26 is made up of upper plate 26A and upper arm 26B. Lower member 27 is made up of lower plate 27A and lower arm 27B.

[0025] As shown in Figure 3, the flange 22 of the pump port 20 has an inner periphery 23 that is convex upward relative to the outer periphery, and a circumferential groove 24 is formed in the inner periphery 23. On the other hand, the mounting flange 32 of the hydrogen pump 30 has an annular ridge 33 formed on its underside. The ridge 33 is configured to provide a seal by compressing a seal member 39 placed in the groove 24. Therefore, when the mounting flange 32 is attached to the flange 22 and fastened with bolts 36, a gap is created between the mounting flange 32 and the outer periphery of the flange 22 in the vertical direction.

[0026] The upper plate 26A is a circular plate member attached to the upper surface of the flange 22 so as to fit into this gap. A plurality of upper arms 26B are arranged in the circumferential direction and are plate members extending downward from the upper plate 26A. The lower plate 27A may be, for example, a semicircular ring member on one side connected to a semicircular ring member on the other side. The lower plate 27A is arranged below the one-side cooling pipe 43 and the other-side cooling pipe 44. A plurality of lower arms 27B are arranged in the circumferential direction and are plate members extending downward from the lower plate 27A. The upper arms 26B and the lower arms 27B are combined with bolts 28A and nuts 28B. As a result, the one-side cooling pipe 43 and the other-side cooling pipe 44 are sandwiched between the lower surface of the flange 22 and the lower plate 27A and are attached to the pump port 20 so that their upper portions contact the lower surface of the flange 22.

[0027] When the pressure of the hydrogen gas accumulated in the upper part of the tank body 11 exceeds a predetermined threshold, the electromagnetic safety valve 50 opens. The hydrogen gas then flows from the boil-off gas port 15 into the one-side cooling pipe 43 and the other-side cooling pipe 44. Because the temperature of this hydrogen gas is extremely low, the flange 22 and the nozzle 21 are cooled by flowing through the one-side cooling pipe 43 and the other-side cooling pipe 44. This reduces the heat input from the flange 22 and the nozzle 21 into the interior of the hydrogen tank 10, improving the thermal insulation performance of the hydrogen tank 10. As a result, the amount of boil-off gas discharged outside the vehicle 200 can be reduced.

[0028] In the above explanation, the boil-off line 40 has been described as being arranged to surround the pump port 20, but this is not limited to this. For example, in addition to the pump port 20, the boil-off line 40 may be arranged to surround the liquid hydrogen filling port 13 and the hydrogen gas return port 14. This reduces the heat input from the liquid hydrogen filling port 13 and the hydrogen gas return port 14 into the hydrogen tank 10, further improving the thermal insulation performance of the hydrogen tank 10. As a result, the amount of boil-off gas discharged outside the vehicle 200 can be further reduced. [Explanation of symbols]

[0029] 10 Hydrogen tank, 11 Tank body, 12 Collector, 13 Liquid hydrogen filling port, 14 Hydrogen gas return port, 15 Boil-off gas port, 20 Pump port, 21 Nozzle, 22 Flange, 23 Inner circumference, 24 Groove, 25 Fixing member, 26 Upper member, 26A Upper plate, 26B Upper arm, 27 Lower member, 27A Lower plate, 27B Lower arm, 28A Bolt, 28B Nut, 30 Hydrogen pump, 31 Drive unit, 32 Mounting flange, 33 Protrusion portion, 34 Shaft portion, 35 Pump portion, 36 Bolt, 39 Seal member, 40 Boil-off line, 41 Boil-off gas port connecting pipe, 42 Upstream T-piece, 43 One side cooling pipe, 44 Other side cooling pipe, 45 Downstream T-piece, 46 Release pipe, 50 Electromagnetic safety valve, 60 reactors, 100 liquid hydrogen storage units, 200 vehicles.

Claims

[Claim 1] A hydrogen tank installed inside the vehicle to store liquid hydrogen; a boil-off line connected to the hydrogen tank and configured to release hydrogen gas vaporized in the hydrogen tank to the outside of the vehicle, the hydrogen tank has at least one port protruding from an outer surface; the boil-off line is disposed to surround at least one of the ports; A liquid hydrogen storage device characterized by:

Images