Boil-off gas recovery system for hydrogen-fueled vehicle including liquid hydrogen tank and recovery method using same

Abstract

According to one embodiment of the present disclosure, the present disclosure discloses a boil-off gas (BOG, Boil Off Gas) recovery system, the boil-off gas recovery system comprising: a liquid hydrogen storage tank (10) for accommodating liquid hydrogen; a metal hydride tank (20) for storing the boil-off gas generated in the liquid hydrogen storage tank (10); the fuel cell (30) is connected with the liquid hydrogen storage tank (10) through a first hydrogen supply pipeline (100); a second hydrogen supply line (200), one end of which is connected to the metal hydride tank (20) and the other end of which is connected to one point on the first hydrogen supply line (100); the first filling pipeline (110) is used for connecting the liquid hydrogen storage tank (10) and the first filling port (11); a boil-off gas transfer line (120), one end of which is connected to one point (P1) on the first filling line (110) and the other end of which is connected to one point (P2) on the second hydrogen supply line (200); and a heat circulation line (300) formed such that at least a portion thereof exchanges heat with the fuel cell (30) and at least another portion thereof exchanges heat with the metal hydride tank (20).

Description

Technical Field

[0001] This disclosure relates to an evaporation gas recovery system and method for hydrogen fuel cell vehicles, including a liquid hydrogen tank. Specifically, it relates to a system and method for storing the evaporation gas of a hydrogen fuel cell vehicle as a metal hydride, wherein the stored metal hydride can be used to release hydrogen by utilizing heat generated in the fuel cell. Background Technology

[0002] Hydrogen is a clean energy source for the future that can replace fossil fuels. In particular, liquid hydrogen, due to its high energy density and lightweight nature, can be applied in a variety of fields, including spacecraft propulsion rocket fuel, magnetic resonance imaging medical equipment, cryopreservation of medical organs, and hydrogen fuel cell commercial vehicles. This liquid hydrogen can be stored at an extremely low temperature of -253 degrees Celsius at atmospheric pressure with a liquid state of 70.8 g per liter, reducing its volume to 1 / 800th of that of existing hydrogen gas.

[0003] In particular, when liquid hydrogen is used in hydrogen fuel cell commercial vehicles, the electricity generated by the fuel cell powers the vehicle, offering advantages such as low cost, high performance, and short charging time. In this case, although the liquid hydrogen needs to be maintained at a temperature of -253 degrees Celsius, due to the influence of external temperature after filling and the insulation performance of the liquid hydrogen storage tank, 3% to 5% of boil-off gas (BOG) is generated daily. This boil-off gas is released externally to maintain the pressure of the liquid hydrogen storage tank. Therefore, there is a need to develop a technology to utilize the boil-off gas continuously generated after filling with liquid hydrogen to prevent hydrogen fuel loss. The inventors have developed a boil-off gas recovery system for hydrogen fuel cell vehicles that improves system operation and energy efficiency by recovering and storing boil-off gas and using the heat generated in the fuel cell to supply the stored hydrogen to the fuel cell.

[0004] Consult relevant patent literature.

[0005] Korean Patent No. 10-2522896 relates to an integrated cooling and vaporization system for a hydrogen fuel cell vehicle. This system enables mutual heat exchange between the cooling water required for cooling the fuel cell and the heat transfer medium required for vaporizing liquid hydrogen. However, the problem of fuel loss caused by the continuous generation of evaporated gas has not been solved.

[0006] Korean Patent Publication No. 10-2020-0012074 relates to an evaporation gas processing system that can recover the cold energy of evaporation gas generated by a hydrogen carrier and store it in a tank containing hydrogen storage metal. However, since the evaporation gas is stored in a separate metal tank and not used, there are limitations in ensuring high energy efficiency.

[0007] (Patent Document 1) Korean Patent No. 10-2522896

[0008] (Patent Document 2) Korean Patent Publication No. 10-2020-0012074

[0009] Content of the invention

[0010] Technical issues

[0011] The purpose of this disclosure is to provide a system and method for recovering evaporated gases generated in a liquid hydrogen storage tank and using the stored evaporated gases as an auxiliary hydrogen supply source.

[0012] Furthermore, the purpose of this disclosure is to provide a method for effectively ensuring the thermal energy required to release hydrogen from a metal hydride tank in order to improve the operation and energy efficiency of the system.

[0013] Furthermore, the purpose of this disclosure is to provide a system and recovery method for improving driving range by recovering evaporated gases generated during the storage of liquid hydrogen in hydrogen fuel cell vehicles, including those with liquid hydrogen tanks.

[0014] The problems to be solved by the present invention are not limited to those mentioned above. Other problems not mentioned should be clearly understood by those skilled in the art through the following description.

[0015] Technical solution

[0016] According to one embodiment of this disclosure, the present invention provides an evaporation gas recovery system, the evaporation gas recovery system comprising: a liquid hydrogen storage tank 10 for containing liquid hydrogen; a metal hydride tank 20 configured to store evaporation gas generated in the liquid hydrogen storage tank 10; a fuel cell 30 connected to the liquid hydrogen storage tank 10 via a first hydrogen supply line 100; a second hydrogen supply line 200, one end connected to the metal hydride tank 20 and the other end connected to a point on the first hydrogen supply line 100; a first filling line 110 for connecting the liquid hydrogen storage tank 10 to a first filling port 11; an evaporation gas delivery line 120, one end connected to a point P1 on the first filling line 110 and the other end connected to a point P2 on the second hydrogen supply line 200; and a heat circulation line 300 configured such that at least a portion exchanges heat with the fuel cell 30 and at least another portion exchanges heat with the metal hydride tank 20.

[0017] Furthermore, preferably, the evaporation gas recovery system further includes: a second filling pipeline 111 for connecting the liquid hydrogen storage tank 10 and the second filling port 12; a filling connection pipeline 112 for connecting a point on the second filling pipeline 111 to another point P3 formed on the first filling pipeline 110 behind the point P1; and a pressure relief valve V1 disposed on the filling connection pipeline 112 for controlling the opening and closing of the filling connection pipeline 112.

[0018] Furthermore, on the first filling line 110, a pressure sensor 13 configured to detect the internal hydraulic pressure of the first filling line 110 is provided behind the other point P3, and a check valve V2 is provided in front of the other point P1 to restrict the flow from the liquid hydrogen storage tank 10 to the first filling port 11. Preferably, the pressure relief valve V1 is opened when the pressure of the fluid measured by the pressure sensor 13 is greater than or equal to a preset pressure.

[0019] Furthermore, the second hydrogen supply line 200 is provided with: a first valve V3, located in front of the point where the second hydrogen supply line 200 intersects with the other end of the evaporation gas delivery line 120; and a second valve V4, located behind the point where the second hydrogen supply line 200 intersects with the other end of the evaporation gas delivery line 120. Preferably, a first regulator 14 is provided on the evaporation gas delivery line 120.

[0020] Furthermore, preferably, a second regulator 21 is provided on the first hydrogen supply line 100, behind the point where the first hydrogen supply line 100 connects to the second hydrogen supply line 200.

[0021] Furthermore, this disclosure provides a method for recovering evaporating gas using an evaporating gas recovery system, the recovery method comprising: step (a), measuring the pressure of fluid flowing in the first filling line 110 by means of the pressure sensor 13; step (b), comparing the pressure value measured by the pressure sensor 13 in step (a) with a preset pressure value by means of an electronic control unit (ECU) 40; step (c-1), in step (b), if it is determined that the measured pressure value is less than the preset pressure value, repeating step (a); and step (c-2), in step (b), if it is determined that the measured pressure value is greater than or equal to the preset pressure value, opening the pressure relief valve V1.

[0022] Furthermore, preferably, the recovery method of this disclosure includes: step (d), when the first valve V3 is open and the second valve V4 is closed, the fluid flowing through the evaporation gas delivery line 120 is stored in the metal hydride tank 20; step (e-1), the heat energy generated in the fuel cell 30 is supplied to the metal hydride tank 20 through the heat circulation line 300; and step (e-2), when the first valve V3 and the second valve V4 are open, the fluid stored in the metal hydride tank 20 is supplied to the fuel cell 30 through the second hydrogen supply line 200 and the first hydrogen supply line 100.

[0023] Invention Effects

[0024] As described above, according to one embodiment of this disclosure, the present invention has the following effect: the evaporated gas generated in the liquid hydrogen storage tank is stored as a metal hydride, and hydrogen is supplied to its use by heating the metal hydride, thereby recovering the evaporated gas generated from the liquid hydrogen storage tank and reducing fuel loss.

[0025] Furthermore, the heat generated in the fuel cell is used as thermal energy to separate hydrogen from the metal hydride through heat exchange with the fuel cell cooling water, and the vaporized hydrogen can be supplied to the fuel cell.

[0026] Furthermore, in vehicles that use hydrogen as an energy source (hydrogen fuel cell commercial vehicles, hydrogen fuel cell electric vehicles, etc.), trains, ships, airplanes, and other means of transportation, the vapors generated during the storage of liquid hydrogen can be recovered and reused, thereby increasing the driving range on a single charge.

[0027] Furthermore, when hydrogen is supplied from the liquid hydrogen storage tank to the fuel cell, the evaporated gas stored in the metal hydride tank can be supplied to the fuel cell as a supplement. Therefore, when the liquid hydrogen fuel in the liquid hydrogen storage tank is insufficient, fuel can generally be replenished from the metal hydride tank. Thus, redundancy can be ensured. Attached Figure Description

[0028] Figure 1 This is a schematic diagram illustrating an evaporative gas recovery system for a hydrogen fuel cell vehicle including a liquid hydrogen tank, according to an embodiment of the present disclosure.

[0029] Figure 2 For illustrative purposes Figure 1 A simplified block diagram of the features of the various structures in the system that are connected to and controlled by the electronic control unit 40.

[0030] Figure 3 This is a flowchart illustrating a recovery method for an evaporative gas recovery system of a hydrogen fuel cell vehicle, including a liquid hydrogen tank, according to an embodiment of the present disclosure. Detailed Implementation

[0031] Hereinafter, some embodiments of the present disclosure will be described in detail with reference to exemplary accompanying drawings. In assigning reference numerals to the structural elements of each drawing, it should be noted that even if the same structural element is presented in different drawings, it will be assigned the same reference numerals as much as possible. Furthermore, in describing the present disclosure, detailed descriptions of related well-known structures or functions will be omitted if it is determined that such detailed descriptions may obscure the spirit of the disclosure.

[0032] In describing the structural elements of embodiments of this disclosure, symbols such as first, second, i), ii), a), and b) may be used. These symbols are used only to distinguish the structural element from other structural elements and do not limit the nature, sequence, or order of the corresponding structural elements. In this specification, when a part "comprises" or "possesses" a structural element, unless otherwise expressly stated to the contrary, it means that other structural elements may also be included, and not that other structural elements are excluded.

[0033] In this disclosure, "upstream" refers to a position in a flow path where the hydrogen has traveled a relatively short distance. For example, in Figure 1 In the filling lines 110 and 111, when fluid flows (moves) from the filling ports 11 and 12 toward the tank 10, this can refer to a point where the movement distance is relatively short. Similarly, in the evaporation gas delivery line 120, when fluid flows from the first filling line 110 toward the second hydrogen supply line 200, this can refer to a point where the movement distance is relatively short. Furthermore, in the hydrogen supply lines 100 and 200, when fluid flows (moves) from the tanks 10 and 20 toward the fuel cell 30, this can refer to a point where the movement distance is relatively short.

[0034] Furthermore, in the published terminology, "downstream" refers to a point in a flow path where the hydrogen flow distance is relatively long. For example, in... Figure 1 In this disclosure, when fluid flows (moves) from filling ports 11 and 12 toward tank 10 on each filling line 110 and 111, it can refer to a point where the movement distance is relatively long. Similarly, when fluid flows from the first filling line 110 toward the second hydrogen supply line 200 on the evaporation gas delivery line 120, it can refer to a point where the movement distance is relatively long. Furthermore, when fluid flows (moves) from tanks 10 and 20 toward fuel cell 30 on each hydrogen supply line 100 and 200, it can refer to a point where the movement distance is relatively long. On the other hand, it should be noted that in this disclosure, "ahead" and "behind" can refer not only to adjacent areas, but also to points that are separated by distances, indicating different movement distances.

[0035] 1. Structural Description

[0036] Figure 1 This is a schematic diagram illustrating an evaporative gas recovery system for a hydrogen fuel cell vehicle including a liquid hydrogen tank, according to an embodiment of the present disclosure. Figure 2 For illustrative purposes Figure 1 A simplified block diagram showing the characteristics of the various structures in the system that are connected to and controlled by the electronic control unit 40.

[0037] Reference Figure 1 and Figure 2 An embodiment of the present disclosure of a vapor recovery system for a hydrogen fuel cell vehicle including a liquid hydrogen tank includes a liquid hydrogen storage tank 10, a metal hydride tank 20, a fuel cell 30, an electronic control unit 40, and a heater 50.

[0038] The liquid hydrogen storage tank 10 is configured to contain liquid hydrogen and the resulting hydrogen vapor gas (hereinafter referred to as "BOG"). It also stores cryogenic liquid hydrogen received from the outside. For transport efficiency, one or more liquid hydrogen storage tanks 10 may be installed in a vehicle (vehicle, ship, etc.) and may be insulated to be suitable for transporting easily vaporized cryogenic liquid hydrogen.

[0039] One end of the first hydrogen supply line 100 is connected to the liquid hydrogen storage tank 10, and the other end is connected to the fuel cell 30. Thus, the liquid hydrogen storage tank 10 and the fuel cell 30 are connected through the first hydrogen supply line 100, and the liquid hydrogen stored in the liquid hydrogen storage tank 10 flows and is supplied to the fuel cell 30.

[0040] The first filling port 11 and the second filling port 12 are connectors for injecting liquid hydrogen into a vehicle. The liquid hydrogen injected through the first filling port 11 and the second filling port 12 is stored in a liquid hydrogen storage tank 10. On the other hand, the vehicle filled with liquid hydrogen through the filling ports 11 and 12 can be a vehicle that uses hydrogen as fuel, such as a hydrogen fuel cell commercial vehicle, a hydrogen fuel cell electric vehicle, a ship, an aircraft, or it can be a hydrogen supply point including a fuel cell 30.

[0041] The metal hydride tank 20 is configured to store the evaporated gas generated in the liquid hydrogen storage tank 10 by filling its interior with a hydrogen storage metal. The hydrogen storage metal stores the evaporated gas as a metal hydride, which can be released in a gaseous state by separating hydrogen from the metal hydride through heating. One or more metal hydride tanks 20 may be provided to store BOG, which may vary depending on the external environment or the insulation performance of the liquid hydrogen storage tank 10. Hydrogen can be stored in the form of metal hydride through an absorption process and stored at high density under ambient temperature and low pressure conditions.

[0042] One end of the second hydrogen supply line 200 is connected to the metal hydride tank 20, and the other end is connected to a point on the first hydrogen supply line 100. Thus, the fluid stored in the metal hydride tank 20 flows to the other end of the first hydrogen supply line 100 and is supplied to the fuel cell 30.

[0043] The second regulator 21 is located downstream of the point where the first hydrogen supply line 100 connects to the second hydrogen supply line 200. The second regulator 21 controls the flow rate of hydrogen flowing from the first hydrogen supply line 100 into the fuel cell 30.

[0044] The first regulator 14 is installed on the evaporation gas delivery line 120 to control the flow rate of hydrogen flowing from the first filling line 110 to the second hydrogen supply line 200.

[0045] One end of the evaporated gas delivery line 120 is connected to a point P1 on the first filling line 110, and the other end is connected to a point P2 on the second hydrogen supply line 200. The evaporated gas delivery line 120 is configured such that evaporated gas generated from the liquid hydrogen storage tank 10 and flowing through the first filling line 110 flows through the second hydrogen supply line 200 to the metal hydride tank 20. A device for maintaining a constant pressure is provided on the evaporated gas delivery line 120, thereby controlling the flow rate of the evaporated gas to improve the storage efficiency of the metal hydride tank 20. As an example, an orifice may be formed on the evaporated gas delivery line 120.

[0046] Because the vapor gas delivery line 120 branches off from a point on the first filling line 110, rather than directly connecting the liquid hydrogen storage tank 10 and the metal hydride tank 20, it has the advantage of allowing flow paths to be designed within a limited layout. This allows for the installation of a separate hydrogen storage system without altering the size of the vehicle or ship's vapor gas recovery system.

[0047] The first filling line 110 is configured to connect the liquid hydrogen storage tank 10 and the first filling port 11, thereby delivering liquid hydrogen supplied to the vehicle through the first filling port 11 to the liquid hydrogen storage tank 10. On the other hand, all or part of the hydrogen generated in the liquid hydrogen storage tank 10 can be released to the outside of the liquid hydrogen storage tank 10 through the first filling line 110.

[0048] The second filling line 111 is configured to connect the liquid hydrogen storage tank 10 and the second filling port 12, thereby delivering liquid hydrogen supplied to the vehicle through the second filling port 12 to the liquid hydrogen storage tank 10.

[0049] Check valves can be installed on either the first filling line 110 or the second filling line 111 to independently restrict the flow of hydrogen from the liquid hydrogen storage tank 10. As an embodiment of this disclosure, check valve V2 is configured to be located upstream of a point P1 on the first filling line 110 to restrict the flow from the liquid hydrogen storage tank 10 to the first filling port 11.

[0050] The filling connection line 112 is used to connect a point on the second filling line 111 to another point P3 that is located behind a point P1 formed on the first filling line 110.

[0051] Pressure sensor 13 is located behind another point P3 on the first filling line 110 to measure the internal hydraulic pressure of the first filling line 110.

[0052] A pressure relief valve V1 is installed on the filling connection line 112 and controls the opening and closing of the filling connection line 112, thereby maintaining the hydraulic pressure inside the first filling line 110 at a constant pressure. The opening and closing of the pressure relief valve V1 is controlled based on the fluid pressure value of the first filling line 110 measured by the pressure sensor 13. This will be described in detail below.

[0053] On the other hand, in this disclosure, preferably, the pressure relief valve V1 is a normally closed type valve. Thus, the pressure relief valve V1 can be opened when there is a separate electrical signal.

[0054] The first valve V3 is configured to be located upstream of the point where the second hydrogen supply line 200 intersects with the other end of the evaporated gas delivery line 120, and is used to control the opening and closing of the evaporated gas delivery line 120. Hydrogen can be controlled to flow from the evaporated gas delivery line 120 into the metal hydride tank 20 via the first valve V3.

[0055] The second valve V4 is configured to be located downstream of the point where the second hydrogen supply line 200 intersects with the other end of the evaporated gas delivery line 120, and is used to control the opening and closing of the evaporated gas delivery line 120. Hydrogen flow into the first hydrogen supply line 100 can be controlled via the second valve V4.

[0056] The fuel cell 30 is connected to the liquid hydrogen storage tank 10 via a first hydrogen supply line 100 and to the metal hydride tank 20 via a second hydrogen supply line 200. The fuel cell 30 is an electrochemical device that converts the chemical energy of hydrogen and oxygen into electrical energy, and can receive hydrogen from either the first hydrogen supply line 100 or the second hydrogen supply line 200 to produce electricity. The heat generated in the fuel cell 30 can be collected by the heat circulation line 300 and delivered to equipment requiring heating for utilization.

[0057] The heat circulation pipeline 300 is configured such that at least a portion exchanges heat with the fuel cell 30, and at least another portion exchanges heat with the metal hydride tank 20. The heat generated in the fuel cell 30 is recovered by the cooling water of the circulating heat circulation pipeline 300, and the recovered heat is transferred and supplied to the metal hydride tank 20 to heat the metal hydride tank 20.

[0058] The electronic control unit 40 is configured to be electrically connected to the pressure sensor 13, the level sensor (not shown), the pressure relief valve V1, the first valve V3, the second valve V4, and the heater 50, and to receive detection values ​​from each structural element or transmit control signals to each structural element (see reference). Figure 2 ).

[0059] The electronic control unit 40 receives the pressure value of the fluid in the first filling line 110 measured by the pressure sensor 13 and compares it with a preset pressure value to output an opening / closing signal for the pressure relief valve V1. When the fluid pressure value in the first filling line 110 measured by the pressure sensor 13 is greater than or equal to the preset pressure value, the pressure relief valve V1 is opened, allowing at least a portion of the fluid flowing in the first filling line 110 to flow to the second filling line 111. When it is determined that the fluid pressure value in the first filling line 110 measured by the pressure sensor 13 is less than the preset pressure value, the pressure relief valve V1 is closed, allowing the hydrogen gas generated in the liquid hydrogen storage tank 10 to flow only to the first filling line 110.

[0060] The electronic control unit 40 can independently control the opening and closing of the first valve V3 and the second valve V4, thereby selectively controlling the flow path of hydrogen moving on the evaporative gas delivery line 120. According to the control signal from the electronic control unit 40, hydrogen can flow along one or more of the following paths: a path through the second hydrogen supply line 200 to the metal hydride tank 20, or a path through the second hydrogen supply line 200 merging with the first hydrogen supply line 100 and being supplied to the fuel cell 30.

[0061] Furthermore, a water level sensor (not shown) installed in the liquid hydrogen storage tank 10 is used to measure the water level of the liquid hydrogen stored inside the liquid hydrogen storage tank 10 and sends the water level measurement value to the electronic control unit 40. The electronic control unit 40 can compare the water level measurement value measured by the water level sensor (not shown) with a preset water level value to control the opening and closing of the first valve V3 and the second valve V4, thereby allowing hydrogen to be supplied to the fuel cell 30. For example, when the water level measurement value measured by the water level sensor (not shown) is less than or equal to the preset water level value, the electronic control unit 40 can open the first valve V3 and the second valve V4 to supply hydrogen. That is to say, when the liquid hydrogen fuel stored in the liquid hydrogen storage tank 10 is insufficient, redundancy can be ensured by supplying hydrogen from the metal hydride tank 20 to the fuel cell 30.

[0062] When a fuel cell charging signal is received, the electronic control unit 40 can heat the liquid hydrogen storage tank 10 by activating the heater 50 to supply hydrogen to the fuel cell 30.

[0063] The heater 50 can be disposed adjacent to the liquid hydrogen storage tank 10 for heating the liquid hydrogen storage tank 10. The liquid hydrogen is heated to produce vaporized hydrogen gas, which is supplied to the first hydrogen supply line 100. The heater 50 can utilize an induction heating-based heating method or a positive temperature coefficient (PTC) heater, etc.

[0064] 2. Recovery method using an evaporative gas recovery system

[0065] Figure 3 This is a flowchart illustrating a recovery method for an evaporative gas recovery system of a hydrogen fuel cell vehicle, including a liquid hydrogen tank, according to an embodiment of the present disclosure.

[0066] Reference Figure 3 The method and process for recovering evaporated gases are described in detail.

[0067] After liquid hydrogen is stored in liquid hydrogen storage tank 10, the pressure of hydrogen flowing in the first filling line 110 is measured by pressure sensor 13 (step S300).

[0068] The pressure information measured in step S300 is transmitted to the electronic control unit 40 in the form of an electrical signal, and is compared with a preset pressure by the electronic control unit 40 (step S310). In this case, the preset pressure is a value input by the manufacturer or user, and appropriate design changes can be made.

[0069] When it is determined that the pressure value measured by the pressure sensor 13 is less than the preset pressure value, steps S300 to S310 will be repeated.

[0070] When it is determined that the pressure value measured by the pressure sensor 13 is greater than or equal to the preset pressure value, the pressure relief valve V1 is opened (step S320).

[0071] Then, the pressure of the fluid flowing in the first filling line 110 is measured by pressure sensor 13. Afterwards, the newly measured pressure value by electronic control unit 40 is compared with the preset pressure.

[0072] The following is for reference Figure 1 This describes the method and process for recovering evaporated gas by opening and closing the first valve V3 and the second valve V4.

[0073] When the first valve V3 is open and the second valve V4 is closed, the hydrogen flowing to the evaporating gas delivery line 120 can be stored in the metal hydride tank 20.

[0074] When the first valve V3 and the second valve V4 are opened, hydrogen stored in the metal hydride tank 20 can be supplied to the fuel cell 30.

[0075] The electronic control unit 40 controls all or part of the devices installed in the heat circulation line 300, thereby providing thermal energy to the metal hydride tank 20. Specifically, the electronic control unit 40 can drive a pump or heat exchange device installed on the heat circulation line 300 to provide the thermal energy generated in the fuel cell 30 to the metal hydride tank 20 through the heat circulation line 300. The metal hydride tank 20 receives heat from the heat circulation line 300 and releases gaseous hydrogen from the metal hydride.

[0076] As the metal hydride tank 20 exchanges heat with the heat circulation pipeline 300, when the first valve V3 and the second valve V4 are opened, the hydrogen stored in the metal hydride tank 20 flows in a gaseous state and is supplied to the fuel cell 30 through the second hydrogen supply pipeline 200 and the first hydrogen supply pipeline 100.

[0077] As described above, the electronic control unit 40 can control the opening and closing of the first valve V3 and the second valve V4, so that when the liquid hydrogen fuel stored in the liquid hydrogen storage tank 10 is insufficient, the hydrogen in the metal hydride tank 20 can be supplied to the fuel cell 30 as an auxiliary.

[0078] On the other hand, when there is insufficient space in the metal hydride tank 20 to store hydrogen, the first valve V3 and the second valve V4 are closed, and the pressure relief valve V1 is opened, so that the hydrogen generated in the liquid hydrogen storage tank 10 can flow back into the liquid hydrogen storage tank 10.

[0079] Hydrogen has a boiling point of approximately -253 degrees Celsius. Various devices and pipes connecting the vapor recovery system of a hydrogen fuel cell vehicle, including a liquid hydrogen tank, which constitutes an embodiment of this disclosure, can be heat-insulated.

[0080] The above description is merely illustrative of the technical concept of one embodiment of this disclosure. Those skilled in the art can make various modifications and variations without departing from the basic characteristics of this embodiment. Therefore, this embodiment is not intended to limit the technical concept of this embodiment, but rather to illustrate the invention. The scope of the technical concept of this embodiment is not limited to these embodiments. The scope of protection of this embodiment should be interpreted by the following claims, and all technical concepts within the same scope should be interpreted as being included within the scope of the rights of this embodiment.

[0081] Explanation of reference numerals in the attached figures

[0082] 10: Liquid hydrogen storage tank

[0083] 11: First filling port

[0084] 12: Second filling port

[0085] 13: Pressure sensor

[0086] 14: First regulator

[0087] 20: Metal hydride container

[0088] 21: Second regulator

[0089] 30: Fuel Cells

[0090] 40: Electronic Control Unit

[0091] 50: Heater

[0092] 100: First hydrogen supply pipeline

[0093] 110: First filling pipeline

[0094] 111: Second filling pipeline

[0095] 112: Fill the connecting pipeline

[0096] 120: Evaporated gas delivery pipeline

[0097] 200: Second hydrogen supply pipeline

[0098] 300: Heat circulation pipeline

[0099] V1: Pressure relief valve

[0100] V2: Check valve

[0101] V3: First Valve

[0102] V4: Second valve.

Claims

1. A boil-off gas recovery system, characterized by, The system comprises: a liquid hydrogen tank (10) for containing liquid hydrogen; a metal hydride tank (20) for storing boil-off gas generated in the liquid hydrogen tank (10); a fuel cell (30) connected to the liquid hydrogen tank (10) through a first hydrogen supply line (100); a second hydrogen supply line (200) having one end connected to the metal hydride tank (20) and the other end connected to a point on the first hydrogen supply line (100); a first filling line (110) for connecting the liquid hydrogen tank (10) to a first filler port (11); a boil-off gas delivery line (120) having one end connected to a point (P1) on the first filling line (110) and the other end connected to a point (P2) on the second hydrogen supply line (200); and a heat circulation line (300) formed to exchange heat with at least the fuel cell (30) and at least the metal hydride tank (20).

2. The boil-off gas recovery system according to claim 1, further comprising: a second filling line (111) for connecting the liquid hydrogen tank (10) to a second filler port (12); a filling connection line (112) for connecting a point on the second filling line (111) to another point (P3) formed on the first filling line (110) rearward of the point (P1); and a pressure relief valve (V1) provided on the filling connection line (112) and configured to control opening and closing of the filling connection line (112).

3. The boil-off gas recovery system according to claim 2, wherein: on the first filling line (110), a pressure sensor (13) for detecting internal hydraulic pressure of the first filling line (110) is provided rearward of the another point (P3), a check valve (V2) is further provided forward of the one point (P1) and configured to restrict flow from the liquid hydrogen tank (10) to the first filler port (11), the pressure relief valve (V1) is opened when the pressure of the fluid measured by the pressure sensor (13) is greater than or equal to a predetermined pressure.

4. The boil-off gas recovery system according to claim 3, wherein: on the second hydrogen supply line (200), a first valve (V3) is provided forward of a point at which the second hydrogen supply line (200) intersects with the other end of the boil-off gas delivery line (120); and a second valve (V4) is provided rearward of the point at which the second hydrogen supply line (200) intersects with the other end of the boil-off gas delivery line (120), a first regulator (14) is provided on the boil-off gas delivery line (120).

5. The boil-off gas recovery system according to claim 1, wherein: ​ ​ A second regulator (21) is provided on the first hydrogen supply line (100) at a point downstream of the point at which the first hydrogen supply line (100) is connected to the second hydrogen supply line (200).

6. An evaporated gas recovery method using the evaporated gas recovery system according to claim 3 or 4, characterized by, Comprising: Step (a), measuring the pressure of fluid flowing in the first filling line (110) by the pressure sensor (13); Step (b), comparing the pressure value measured in the step (a) by the pressure sensor (13) with a preset pressure value by the electronic control unit (40); Step (c-1), in the step (b), when it is judged that the measured pressure value is less than the preset pressure value, repeating the step (a); and Step (c-2), in the step (b), when it is judged that the measured pressure value is greater than or equal to the preset pressure value, opening the pressure relief valve (V1).

7. An evaporated gas recovery method using the evaporated gas recovery system according to claim 4, characterized by, Comprising: Step (d), when the first valve (V3) is open and the second valve (V4) is closed, fluid stored in the metal hydride tank (20) flows through the boil-off gas delivery line (120); Step (e-1), heat energy generated in the fuel cell (30) is supplied to the metal hydride tank (20) through the heat circulation line (300); and Step (e-2), when the first valve (V3) and the second valve (V4) are open, fluid stored in the metal hydride tank (20) is supplied to the fuel cell (30) through the second hydrogen supply line (200) and the first hydrogen supply line (100).

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