Gas supply system, ship, and gas supply method

Abstract

A gas supply system according to an embodiment of the present invention comprises: a gas consumption device that can consume hydrogen gas; a tank for housing hydrogen gas; a first supply line that connects the tank to the gas consumption device; a first compressor that is disposed in the first supply line, and that is configured to be able to compress hydrogen gas discharged from the tank and guided through the first supply line to a pressure equal to or greater than a required pressure for the gas consumption device; an inert gas line through which inert gas is guided to the tank; a second supply line that is connected to a portion, of the first supply line, upstream of the first compressor, and is connected to a portion, of the first supply line, downstream of the first compressor; and a second compressor that is disposed in the second supply line, and that is configured to be able to compress a mixed gas that is a mixture of the inert gas and the hydrogen gas and that is discharged from the tank by the inert gas being guided to the tank through the inert gas line, to a pressure equal to or greater than the required pressure for the gas consumption device.

Description

Technical Field

[0001] The present disclosure relates to a gas supply system for supplying gas from a tank to a gas consumer, a ship equipped with the gas supply system, and a gas supply method for supplying gas from a tank to a gas consumer.

Background Art

[0002] In recent years, systems for storing and transporting liquefied hydrogen have been developed (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In order to perform maintenance on a liquefied hydrogen storage tank, first, after removing liquefied hydrogen from the tank to fill the inside of the tank with hydrogen gas, the hydrogen gas inside the tank is replaced with an inert gas, and then the inert gas filled inside the tank is replaced with air. Conversely, in order to store liquefied hydrogen in the tank after maintenance, before supplying liquefied hydrogen to the tank, the air inside the tank is replaced with an inert gas, and then the inert gas inside the tank is further replaced with hydrogen gas. It is desired to efficiently carry out the gas replacement operation inside the tank.

[0005] An object of the present disclosure is to provide a gas supply system, a ship, and a gas supply method that enable the gas replacement operation inside the tank to be carried out efficiently.

Means for Solving the Problems

[0006] To solve the above problems, a gas supply system according to one aspect of the present disclosure includes a gas consumer that can consume hydrogen gas, a tank that stores hydrogen gas, a first supply line that connects the tank and the gas consumer, a first compressor that is disposed in the first supply line and is discharged from the tank and configured to compress the hydrogen gas guided by the first supply line to a pressure equal to or higher than the required pressure of the gas consumer, an inert gas line that guides an inert gas to the tank, a second supply line that connects to an upstream portion of the first compressor in the first supply line and a downstream portion of the first compressor in the first supply line, and a second compressor that is disposed in the second supply line and is configured to compress a mixed gas of the inert gas and the hydrogen gas discharged from the tank when the inert gas is guided to the tank by the inert gas line to a pressure equal to or higher than the required pressure of the gas consumer.

[0007] A gas supply system according to another aspect of the present disclosure includes a first gas consumer that can consume hydrogen gas, a tank that stores hydrogen gas, a first supply line that connects the tank and the first gas consumer, a first compressor that is disposed in the first supply line and is discharged from the tank and configured to compress the hydrogen gas guided by the first supply line to a pressure equal to or higher than the required pressure of the first gas consumer, an inert gas line that guides an inert gas to the tank, a second gas consumer that can consume a mixed gas of the inert gas and the hydrogen gas, a second supply line that connects to an upstream portion of the first compressor in the first supply line and the second gas consumer, and a second compressor that is disposed in the second supply line and is configured to compress the mixed gas to a pressure equal to or higher than the required pressure of the second gas consumer.

[0008] A ship according to one aspect of the present disclosure includes any of the above gas supply systems.

[0009] A gas supply method according to one aspect of the present disclosure is a gas supply method for supplying gas discharged from a tank. When discharging hydrogen gas from the tank in a state where hydrogen gas is stored, the hydrogen gas discharged from the tank is guided to a first compressor and compressed, and the compressed hydrogen gas is consumed by a first gas consumer. When discharging a mixed gas of an inert gas and hydrogen gas from the tank, the mixed gas discharged from the tank is guided to a second compressor of a type different from the first compressor and compressed, and the compressed mixed gas is consumed by the first gas consumer or a second gas consumer of a type different from the first gas consumer.

Effects of the Invention

[0010] According to the present disclosure, it is possible to provide a gas supply system, a ship, and a gas supply method that enable the work of replacing the gas in the tank to proceed efficiently.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Modes for Carrying Out the Invention

[0012] Hereinafter, a gas supply system according to an embodiment will be described with reference to the drawings. In the following, the same or corresponding elements are denoted by the same reference numerals throughout all the drawings, and redundant descriptions are omitted.

[0013] <First Embodiment> FIG. 1 shows a schematic configuration diagram of a gas supply system 1A according to the first embodiment. The gas supply system 1A described in this embodiment is mounted on a ship. The ship is a hydrogen carrier that transports liquefied hydrogen and includes a tank 2 for storing the liquefied hydrogen as cargo. In FIG. 1, one tank 2 is shown, but the ship may include a plurality of tanks 2.

[0014] Also, a main engine 3 is mounted on the hull of the ship. In this embodiment, the main engine 3 is a combination of two boilers 4 and one steam turbine 5.

[0015] The boiler 4 uses hydrogen gas as fuel. In this embodiment, the boiler 4 uses one or both of hydrogen gas as fuel gas and fuel oil as fuel. Therefore, even when hydrogen gas is not supplied to the boiler 4, or when the hydrogen gas supplied to the boiler 4 does not reach the required amount of the boiler 4, the boiler 4 can be operated by supplying fuel oil to the boiler 4. The boiler 4 may also be referred to as a gas consumer or a first gas consumer. The steam turbine 5 drives the propulsion shaft of the propeller 6 using the steam generated by the two boilers 4. The propeller 6 is, for example, a propeller. Note that the number of boilers 4 and the number of steam turbines 5 mounted as the main engine 3 on the hull are not limited to this. For example, the number of turbines 5 may be plural.

[0016] The main engine 3 uses the boil-off gas generated by the evaporation of liquefied hydrogen in the tank 2 as propulsion fuel. In this embodiment, the gas supply system 1A supplies the hydrogen gas in the tank 2 to the main engine 3 for propulsion. The tank 2 and the boiler 4 are connected by a first supply line 10. The first supply line 10 guides the gas discharged from the tank 2 to the boiler 4. A first compressor 7 is arranged in the first supply line 10. Note that the line described below, including the first supply line 10, is a flow path for guiding a fluid and is composed of piping or the like.

[0017] In this embodiment, the tank 2 is a tank for storing liquefied hydrogen. In a state where liquefied hydrogen is stored in the tank 2, the gas layer, which is the space above the liquid level of the liquefied hydrogen in the tank 2, is filled with hydrogen gas. The gas layer contains boil-off gas generated by the vaporization of liquefied hydrogen in the tank 2. The upstream end of the first supply line 10 is disposed at the upper part in the tank 2.

[0018] Further, the tank 2 is provided with a pressure gauge 8. The pressure gauge 8 detects the pressure of the gas layer in the tank 2. That is, from the pressure measured by the pressure gauge 8, an increase in pressure due to the generation of boil-off gas can be detected.

[0019] Also, the tank 2 is connected to an inert gas generator 31 by an inert gas line 32. More specifically, the upstream end of the inert gas line 32 is connected to the inert gas generator 31, and the downstream end of the inert gas line 32 is disposed at the lower part (for example, the bottom) in the tank 2. However, the downstream end of the inert gas line 32 does not necessarily have to be disposed at the lower part in the tank 2. An on-off valve 33 capable of opening and closing the flow path is disposed in the inert gas line 32.

[0020] The inert gas generator 31 generates an inert gas. Examples of the inert gas include nitrogen, argon, carbon dioxide, and the like. The inert gas generator 31 is used to replace the hydrogen gas in the tank 2 with an inert gas. The inert gas generator 31 is operated, for example, by manual operation of an operator before performing the gas replacement. By opening the on-off valve 33 and operating the inert gas generator 31, the inert gas generated by the inert gas generator 31 is introduced into the tank 2 through the inert gas line 32. As a result, a mixed gas of the inert gas and the hydrogen gas is discharged from the tank 2 through the upstream end of the first supply line 10.

[0021] In this embodiment, a gas concentration meter 18 is disposed in a portion upstream of the first compressor 7 in the first supply line 10 (more specifically, the first common flow path 11 described later). The gas concentration meter 18 measures the hydrogen concentration. For example, during gas replacement, it measures the ratio of hydrogen gas in the mixed gas discharged from the tank 2. That is, based on the hydrogen concentration measured by the gas concentration meter 18, it is possible to grasp, for example, the progress of gas replacement. The gas concentration meter 18 may not be provided in the first supply line 10 and may be disposed in the tank 2, for example.

[0022] The first compressor 7 is a compressor for compressing hydrogen gas. The first compressor 7 is configured to be able to compress the hydrogen gas guided by the first supply line 10 to a pressure equal to or higher than the required pressure of the boiler 4, which is the first gas consumer. Further, for example, the maximum discharge amount of the first compressor 7 is equal to or greater than the required flow rate of the boiler 4, which is the first gas consumer. The first compressor 7 is used, for example, when a ship equipped with the gas supply system 1A transports hydrogen from a hydrogen supply location (hereinafter also referred to as a loading location), such as a hydrogen production base, to a hydrogen demand location (hereinafter also referred to as an unloading location). For example, when the ship is sailing from the loading location to the unloading location, in the tank 2, the pressure in the tank 2 increases due to the generation of boil-off gas. In order to suppress the pressure increase in the tank 2, the boil-off gas is discharged from the tank 2. The discharged hydrogen gas, which is the boil-off gas, can be used in the boiler 4 as propulsion fuel by being compressed by the first compressor 7 to a pressure equal to or higher than the required pressure of the boiler 4.

[0023] The first supply line 10 includes a first common flow path 11, two first branch flow paths 12, a second common flow path 13, and two second branch flow paths 14. The first common flow path 11, the two first branch flow paths 12, the second common flow path 13, and the two second branch flow paths 14 are connected in this order from the upstream side to the downstream side.

[0024] The first common flow path 11 extends from the tank 2. An on-off valve 17 capable of opening and closing the flow path is arranged in the first common flow path 11. The two first branch flow paths 12 branch into two at a branch point 10a which is the downstream end of the first common flow path 11. In the present embodiment, the gas supply system 1A includes two first compressors 7 arranged in parallel with each other in order to ensure redundancy. The two first compressors 7 are respectively arranged in the two first branch flow paths 12. Note that the number of the first compressors 7 included in the gas supply system 1A may be one or three or more. The number of the first branch flow paths 12 can also vary according to the number of the first compressors 7.

[0025] In the present embodiment, the first compressor 7 is, for example, a turbo type or a reciprocating type. The two first compressors 7 may be of the same type as each other or may be of different types from each other. The first compressor 7 may be a compressor of a type other than the turbo type or the reciprocating type.

[0026] An on-off valve 15 capable of opening and closing the flow path is provided in the upstream portion of each first branch flow path 12 from the first compressor 7.

[0027] The second common flow path 13 extends from a confluence point 10b of the two first branch flow paths 12. The two second branch flow paths 14 branch into two at a branch point 10c which is the downstream end of the second common flow path 13. The downstream ends of the two second branch flow paths 14 are respectively connected to the two boilers 4. An on-off valve 16 capable of opening and closing the second branch flow path 14 is provided in each second branch flow path 14.

[0028] Further, the gas supply system 1A includes a second supply line 20, a second compressor 9 arranged in the second supply line 20, and a gas engine 41 for power generation.

[0029] The second supply line 20 branches and extends from an upstream portion of the first supply line 10 from the first compressor 7. More specifically, the upstream end 20a of the second supply line 20 is connected to the first common flow path 11.

[0030] The second supply line 20 includes a common flow path 21, a first branch flow path 22, and a second branch flow path 23. The upstream end 20a of the common flow path 21 extends from a portion upstream of the first compressor 7 in the first supply line 10. The first branch flow path 22 and the second branch flow path 23 branch into two at a branch point 20b which is the downstream end of the common flow path 21. That is, the second supply line 20 has two downstream ends, specifically, the downstream end 20c of the first branch flow path 22 and the downstream end 20d of the second branch flow path 23.

[0031] The downstream end 20c of the first branch flow path 22 is connected to the first supply line 10 (more specifically, the second common flow path 13). That is, the line extending from the upstream end 20a to the downstream end 20c in the second supply line 20 constitutes a bypass line that bypasses the first compressor 7. The downstream end 20d of the second branch flow path 23 is connected to the gas engine 41.

[0032] The second compressor 9 is disposed in the common flow path 21 in the second supply line 20. The second compressor 9 is basically a compressor used when replacing the gas in the tank 2.

[0033] For example, when performing maintenance on the tank 2, first, the inside of the tank 2 is made into a state filled with hydrogen gas (that is, a hydrogen gas atmosphere) by taking out liquefied hydrogen from the tank 2. Then, in order to purge the hydrogen gas from the tank 2, an inert gas is supplied into the tank 2 through the inert gas line 32. As a result, a mixed gas of the inert gas and the hydrogen gas is discharged from the tank 2 through the upstream end of the first supply line 10. The second compressor 9 is used to compress the mixed gas discharged at this time. The second compressor 9 is configured to be able to compress the mixed gas to a pressure equal to or higher than the required pressure of the boiler 4. During the gas replacement, the mixed gas discharged from the tank 2 is compressed by the second compressor 9 to a pressure equal to or higher than the required pressure of the boiler 4 and then consumed by the boiler 4.

[0034] Also, for example, after the maintenance of the tank 2, the inside of the tank 2 is replaced from air with an inert gas. Then, at a base (e.g., a storage yard) where hydrogen gas is supplied, in order to purge the inert gas from the tank 2, hydrogen gas is supplied into the tank 2 through a hydrogen line 60 or the like described later. As a result, a mixed gas of the inert gas and hydrogen gas is discharged from the tank 2 through the upstream end of the first supply line 10. The second compressor 9 can also be used for compressing the mixed gas discharged at this time.

[0035] The proper use of the first compressor 7 and the second compressor 9 will be described in more detail. The first compressor 7 is suitable for pumping hydrogen gas with an extremely small specific gravity. The first compressor 7 can compress hydrogen gas to a pressure equal to or higher than the required pressure of the boiler 4 which is the first gas consumer. Therefore, for example, hydrogen gas which is boil-off gas discharged from the tank 2 is compressed by the first compressor 7 and used as propulsion fuel in the boiler 4. However, since the first compressor 7 is for pumping hydrogen gas, even if an attempt is made to pump the mixed gas using the first compressor 7, there is a possibility that the hydrogen gas in the mixed gas discharged from the tank 2 cannot be consumed by the boiler 4 which is the first gas consumer, or even if the first compressor 7 can be used for compressing the mixed gas, it may take too much time to pump the mixed gas compared to the case of using the second compressor 9.

[0036] Therefore, the present embodiment includes a second compressor 9 for pumping the mixed gas discharged from the tank 2 during gas replacement to a gas consumer. The second compressor 9 can compress the mixed gas to a pressure equal to or higher than the required pressure of the boiler 4 which is the first gas consumer. Also, the second compressor 9 can compress the mixed gas to a pressure equal to or higher than the required pressure of the gas engine 41 which is the second gas consumer.

[0037] For example, the maximum discharge amount of hydrogen gas by the second compressor 9 is smaller than the maximum discharge amount of hydrogen gas by the first compressor 7. Therefore, for example, when the generation amount of boil-off gas per unit time is large, the second compressor 9 may not be able to sufficiently pump hydrogen gas, and there is a possibility that the pressure rise inside the tank 2 cannot be suppressed.

[0038] As described above, in this embodiment, the gas supply system 1A includes a first compressor 7 suitable for pumping a gas with a low specific gravity and a second compressor 9 suitable for pumping a gas with a high specific gravity. Therefore, it is possible to selectively use the compressors according to the application, reliably suppress the pressure rise in the tank 2, and efficiently perform the replacement of the hydrogen gas in the tank 2 during gas replacement.

[0039] In this embodiment, the second compressor 9 is a different type of compressor from the two first compressors 7. The second compressor 9 is, for example, a rotary type. The second compressor 9 may be a type of compressor other than the rotary type. Note that the second compressor 9 may be capable of compressing the mixed gas to a pressure equal to or higher than either the required pressure of the boiler 4, which is the first gas consumer, or the required pressure of the gas engine 41, which is the second gas consumer.

[0040] An on-off valve 24 capable of opening and closing the flow path is disposed in the portion upstream of the second compressor 9 in the second supply line 20. Also, an on-off valve 25 capable of opening and closing the flow path is disposed in the first branch flow path 22. Further, an on-off valve 26 capable of opening and closing the flow path is disposed in the second branch flow path 23.

[0041] The gas engine 41 uses hydrogen gas as fuel and drives the generator 42. In this embodiment, the gas engine 41 is a dual-fuel engine that burns one or both of hydrogen gas as fuel gas and fuel oil. The gas engine 41 can also be referred to as the second gas consumer.

[0042] Hydrogen gas used as fuel is introduced into the gas engine 41 through the second branch flow path 23. Also, the required pressure of the gas engine 41 may be the same as or different from the required pressure of the boiler 4. For example, depending on the situation, hydrogen gas compressed by the first compressor 7 or a mixed gas compressed by the second compressor 9 may be introduced into the gas engine 41.

[0043] When hydrogen gas compressed by the first compressor 7 is introduced into the gas engine 41, the hydrogen gas compressed by the first compressor 7 flows from the downstream end 20c in the second supply line 20 toward the branch point 20b. That is, the direction of the gas flow in the portion between the downstream end 20c and the branch point 20b in the second supply line 20 can change according to the situation.

[0044] Each of the first compressor 7 and the second compressor 9 has a variable discharge amount. The discharge amount of each compressor is controlled by the control device 50. The control device 50 is a so-called computer and has an arithmetic processing unit such as a CPU and a storage unit such as a ROM and a RAM (none of which are shown). Programs executed by the arithmetic processing unit, various fixed data, etc. are stored in the storage unit.

[0045] For example, the control device 50 controls the first compressor 7 to change the gas supply amount to the boiler 4. For example, when there is a change in the gas consumption in the main unit 3, such as switching from the state of operating two boilers 4 to the state of operating only one boiler 4, the control device 50 controls the first compressor 7 to reduce the discharge amount of the first compressor 7. Note that the above-mentioned on-off valves 15, 16, 17, 24, 25, 26, 33, 64, 65, 66, 72 are all manually operated valves, but some or all of the above-mentioned on-off valves 15, 16, 17, 24, 25, 26, 33, 64, 65, 66, 72 may be automatic control valves controlled by the control device 50.

[0046] The gas supply system 1A further includes a hydrogen line 60. The hydrogen line 60 is a flow path for supplying hydrogen gas or liquefied hydrogen to the tank 2 or discharging hydrogen gas or liquefied hydrogen from the tank 2. In the present embodiment, the hydrogen line 60 is connected to the first supply line 10 and the inert gas line 32. That is, a part of the first supply line 10 and a part of the inert gas line 32 are also used as flow paths for supplying hydrogen gas or liquefied hydrogen to the tank 2 or discharging hydrogen gas or liquefied hydrogen from the tank 2.

[0047] Specifically, the hydrogen line 60 includes a common flow path 61, a first branch flow path 62, and a second branch flow path 63. One end of the common flow path 61 is configured to be connectable to a source of hydrogen gas or liquefied hydrogen, or a destination for hydrogen gas or liquefied hydrogen. For example, a connector that can be connected to a loading arm installed at a storage or unloading site is provided at one end of the common flow path 61. At a branch point 60a, which is the other end of the common flow path 61, the first branch flow path 62 and the second branch flow path 63 branch off in two directions.

[0048] One end of the first branch flow path 62 is connected to the common flow path 61 at the branch point 60a, and the other end of the first branch flow path 62 is connected to a portion between the tank 2 and the on-off valve 17 in the common flow path 11 of the first supply line 10. One end of the second branch flow path 63 is connected to the common flow path 61 at the branch point 60a, and the other end of the second branch flow path 63 is connected to a portion between the tank 2 and the on-off valve 33 in the inert gas line 32.

[0049] An on-off valve 64 that can open and close the flow path is arranged in the common flow path 61. An on-off valve 65 that can open and close the flow path is arranged in the first branch flow path 62. An on-off valve 66 that can open and close the flow path is arranged in the second branch flow path 63.

[0050] Further, the gas supply system 1A further includes a connection line 71 that connects the first common flow path 11 and the inert gas line 32. For example, as will be described later, the connection line 71 is used when replacing the inert gas in the tank 2 with hydrogen gas. An on-off valve 72 that can open and close the flow path is arranged in the connection line 71.

[0051] One end of the connection line 71 is connected to a portion between the connection point with the upstream end 20a of the second supply line 20 in the first common flow path 11 and the on-off valve 17. The other end of the connection line 71 is connected to a portion between the tank 2 and the on-off valve 33 in the inert gas line 32. Note that one end of the connection line 71 may be connected to the second supply line 20 instead of the first common flow path 11. For example, one end of the connection line 71 may be connected to a portion between the upstream end 20a in the second supply line 20 and the on-off valve 24. Further, the other end of the connection line 71 may be connected to a portion on the inert gas line 32 side from the on-off valve 66 in the second branch flow path 63.

[0052] Next, a gas supply method implemented by the gas supply system 1A of the present embodiment will be described. In the following description, a method of supplying boil-off gas from the tank 2 storing liquefied hydrogen to the boiler 4 and a gas supply method performed during gas replacement for replacing the gas in the tank 2 with another gas will be described.

[0053] (Supply of Boil-off Gas) When the ship is sailing from the loading place to the unloading place, the tank 2 is in a full-load state where most of the space inside is occupied by liquefied hydrogen. During navigation, in the tank 2, hydrogen gas is generated by evaporation of liquefied hydrogen. The ship uses this hydrogen gas as fuel gas for propulsion.

[0054] Specifically, open the on-off valves 15, 16, 17, close the on-off valves 24, 25, 26, 33, 64, 65, 66, 72, and operate the first compressor 7. By the first compressor 7, hydrogen gas is pumped from the tank 2 to the boiler 4.

[0055] During navigation, when the change in the hull's sway occurs due to sudden rough weather or the like, the amount of boil-off gas generated in the tank 2 may increase. In this case, by increasing the gas supply amount to the boiler 4 by the first compressor 7, the increase in the tank pressure accompanying the increase in the boil-off gas amount can be suppressed. However, since it is difficult for the steam turbine 5 to immediately change the load, the gas supply amount to the boiler 4 will exceed the gas consumption amount of the boiler 4.

[0056] In this embodiment, when the gas supply amount to the boiler 4 exceeds the gas consumption amount of the boiler 4, the boil-off gas surplus between the first compressor 7 and the boiler 4 in the first supply line 10 is effectively utilized by the gas engine 41 which is the second gas consumer. Specifically, the on-off valves 25 and 26 are opened, and hydrogen gas is guided to the gas engine 41 through the first branch flow path 22 and the second branch flow path 23, and consumed by the gas engine 41.

[0057] The timing for guiding hydrogen gas to the gas engine 41, that is, the timing for opening the on-off valves 25 and 26, can be determined using an index that can directly or indirectly determine that the gas supply amount to the boiler 4 exceeds the gas consumption amount of the boiler 4. For example, when the measured value of the pressure gauge 8 becomes equal to or higher than a predetermined value, the on-off valves 25 and 26 may be opened, or when the discharge amount of the first compressor 7 becomes equal to or higher than a predetermined value, the on-off valves 25 and 26 may be opened.

[0058] The electricity generated by the generator 42 driven by the gas engine 41 is distributed to the electrical equipment on the ship. The electricity generated by the generator 42 may be stored in a battery or the like.

[0059] (Gas supply performed during gas replacement before maintenance) Next, the gas supply performed during gas replacement before maintenance of the tank 2 will be described. The maintenance is carried out, for example, at a predetermined dock. In this embodiment, however, the gas replacement is started not after arriving at the dock but before arriving at the dock.

[0060] For example, when the ship arrives at the port with liquefied hydrogen stored in the tank 2, the liquefied hydrogen in the tank 2 is unloaded. As a result, the tank 2 changes from a full-load state to an empty-load state where there is no or little liquefied hydrogen in the space inside the tank 2. In the empty-load state of the tank 2, the inside of the tank 2 is filled with hydrogen gas. Ships usually require regular maintenance, such as a 2.5-year cycle or a 5-year cycle. When maintenance is required, after the unloading is completed, instead of sailing the ship towards the next loading port, it sails towards the dock for maintenance.

[0061] In this embodiment, gas replacement is performed while the ship is sailing towards the dock. Specifically, the on-off valves 15, 26, 64, 65, 66, 72 are closed, the on-off valves 16, 17, 24, 25, 33 are opened, and then the inert gas generator 31 and the second compressor 9 are operated. As a result, inert gas is supplied from the inert gas generator 31 to the tank 2 in a state where hydrogen gas is stored. As a result, a mixed gas of inert gas and hydrogen gas is discharged from the tank 2 through the upstream end of the first supply line 10.

[0062] The mixed gas discharged from the tank 2 is led to the second compressor 9 through the common flow path 21 of the second supply line 20, and hydrogen gas is pumped from the tank 2 to the boiler 4 through the first branch flow path 22. Among the mixed gas led to the boiler 4, the hydrogen gas is used as the fuel gas of the boiler 4, and the mixed gas is burned.

[0063] In addition, when the amount of hydrogen gas in the mixed gas supplied to the boiler 4 is not sufficient as the fuel gas of the boiler 4, fuel oil is supplied to the boiler 4. When the inert gas is sent to the bottom of the tank 2, basically, the inert gas with a specific gravity greater than that of hydrogen gas accumulates at the bottom of the tank 2. For this reason, immediately after starting the supply of inert gas to the tank 2, the concentration of hydrogen gas discharged from the tank 2 is high. As the supply of inert gas continues, the concentration of hydrogen gas discharged from the tank 2 decreases. Even in this case, by supplying fuel oil to the boiler 4, it can be processed smoothly.

[0064] In addition, the maximum discharge amount of hydrogen gas by the second compressor 9 is smaller than the maximum discharge amount of hydrogen gas by each first compressor 7. However, when sailing from the destination to the dock, since the tank 2 is in an empty state, there is no risk of the tank pressure rising due to boil-off gas. Therefore, when the tank 2 is in an empty state, the flow rate of discharging hydrogen gas from the tank 2 may be smaller than when the tank 2 is in a full state, and even the second compressor 9 can sufficiently meet the requirements. Also, even when the amount of hydrogen gas supplied to the boiler 4 is insufficient, the ship can sail smoothly by supplying fuel oil to the boiler 4.

[0065] In this way, on the way to the dock, the hydrogen gas in the tank 2 can be replaced with an inert gas. After that, the inert gas in the tank 2 is replaced with air so that the maintenance of the tank 2 can be performed.

[0066] (Gas supply during gas replacement after maintenance) Next, the gas supply performed during the gas replacement after the maintenance of the tank 2 will be described. The gas replacement after maintenance is carried out to store liquefied hydrogen in the tank 2.

[0067] That is, after the maintenance is completed at the dock, the air in the tank 2 is replaced with an inert gas. In this embodiment, while sailing the ship from the dock to the loading area, the operation of replacing the air in the tank 2 with an inert gas is performed.

[0068] After arriving at the loading area, the inert gas filled in the tank 2 is replaced with hydrogen gas. Specifically, by connecting the loading arm installed at the loading area to one end of the common flow path 61, the tank 2 and the hydrogen gas supply source (for example, a hydrogen gas generation device) are connected. Then, the on-off valves 15, 17, 33, 66, etc. are closed, the on-off valves 24, 64, 65, 72 are opened, and hydrogen gas is supplied from the hydrogen gas supply source to the tank 2 through the common flow path 61, the first branch flow path 62, and the first common flow path 11.

[0069] As hydrogen gas, which has a lower specific gravity than the inert gas, accumulates in the upper part of the tank 2, a mixed gas of the inert gas and hydrogen gas is discharged from the tank 2 through the end of the inert gas line 32. Immediately after the supply of hydrogen gas to the tank 2 is started, the concentration of hydrogen gas discharged from the tank 2 is low. As the supply of hydrogen gas continues, the concentration of hydrogen gas discharged from the tank 2 increases.

[0070] The mixed gas discharged from the tank 2 is led to the second compressor 9 through the inert gas line 32, the connection line 71, the first common flow path 11, and the common flow path 21. The mixed gas compressed by the second compressor 9 may be led to the gas engine 41 and consumed by the gas engine 41 by opening, for example, the on-off valve 26. Alternatively, the mixed gas compressed by the second compressor 9 may be led to a gas combustion device (GCU; Gas Combustion Unit; see FIG. 4), which is not shown in FIG. 1, and consumed. For example, when the hydrogen concentration measured by the gas concentration meter 18 is equal to or higher than the required concentration of the gas engine 41, the on-off valve 26 is opened and the mixed gas is consumed by the gas engine 41. When the hydrogen concentration is lower than the required concentration of the gas engine 41, the on-off valve 26 may be closed and the GCU may be used for processing.

[0071] After the gas replacement from the inert gas to hydrogen gas is completed, the on-off valves 24, 33, 65, 72, etc. are closed, and the on-off valves 15, 17, 32, 64, 72, etc. are opened to introduce liquefied hydrogen into the tank 2. Whether or not the gas replacement from the inert gas to hydrogen gas is completed can be determined, for example, by whether or not the hydrogen concentration measured by the gas concentration meter 18 exceeds a reference value. Liquefied hydrogen is supplied from the liquefied hydrogen supply source to the tank 2 through the common flow path 61, the second branch flow path 63, and the inert gas line 32.

[0072] By supplying liquefied hydrogen into tank 2, hydrogen gas is discharged from tank 2 through the upstream end of the first supply line 10. The discharged hydrogen gas is led to the first compressor 7 through the first supply line 10. The hydrogen gas compressed by the first compressor 7 may be led to the gas engine 41 and consumed by the gas engine 41 by opening, for example, the on-off valves 25 and 26. Alternatively, the hydrogen gas compressed by the first compressor 7 may be led to a GCU (not shown in FIG. 1) and consumed.

[0073] As described above, in the gas supply system 1A of the present embodiment, separately from the first compressor 7 for pumping off-gas, a second compressor 9 capable of compressing a mixed gas of inert gas and hydrogen gas to a pressure equal to or higher than the required pressure of the boiler 4 is provided. Therefore, it is possible to selectively use the compressors according to the application, reliably suppress the pressure rise in tank 2, and efficiently perform the replacement of the hydrogen gas in tank 2 during gas replacement.

[0074] Since the ship is equipped with the second compressor 9 for pumping the mixed gas separately from the first compressor 7 for pumping off-gas, for example, when the ship sails towards the dock for maintenance work, the gas replacement for replacing the hydrogen gas in tank 2 with inert gas can be performed. Also, the mixed gas of inert gas and hydrogen gas can be effectively utilized by the propulsion boiler 4.

[0075] In ships where gas replacement work cannot be performed on board, it is necessary to return the mixed gas to land after landing, and the maintenance work cannot be smoothly carried out. In contrast, in the present embodiment, while effectively using the hydrogen gas in tank 2 to be replaced with inert gas, the gas replacement in tank 2 can be advanced during navigation, and it becomes possible to smoothly shift to the maintenance work.

[0076] Incidentally, the specific gravity of the inert gas is extremely large compared to that of hydrogen gas. Therefore, even if an attempt is made to pump the mixed gas using the first compressor 7 for pumping hydrogen gas, there is a possibility that the hydrogen gas in the mixed gas discharged from the tank 2 cannot be consumed by the boiler 4 which is the first gas consumer, or even if the first compressor 7 can be used for compressing the mixed gas, it may take too much time to pump the mixed gas compared to the case of using the second compressor 9. However, in the present embodiment, separately from the first compressor 7 for hydrogen gas that compresses hydrogen gas, a second compressor 9 capable of compressing the mixed gas to a pressure equal to or higher than the required pressure of the boiler 4 is provided. Therefore, it is possible to properly select the compressor to be used between the case of compressing hydrogen gas during normal navigation and the case of compressing the mixed gas discharged from the tank 2 when performing gas replacement on the way to the dock. For this reason, it is possible to avoid the situation where the performance required for the first compressor 7 becomes high or the first compressor 7 is overloaded by compressing the mixed gas.

[0077] Incidentally, depending on the type of gas consumer, there are some that cannot consume the mixed gas unless the proportion of hydrogen gas in the mixed gas is above a certain level. However, in the present embodiment, since the gas consumer of the main engine 3 is the boiler 4, the mixed gas can be consumed regardless of the mixing ratio of hydrogen gas and inert gas.

[0078] <Second Embodiment> FIG. 2 is a schematic configuration diagram of a gas supply system 1B according to the second embodiment. In the gas supply system 1B according to the second embodiment, unlike the gas supply system 1A according to the first embodiment, the second supply line 20 does not include the second branch flow path 23. That is, the gas compressed by the first compressor 7 and the gas compressed by the second compressor 9 are both led to the boiler 4. The second compressor 9 is capable of compressing the mixed gas to a pressure equal to or higher than the required pressure of the boiler 4 which is the first gas consumer. The second compressor 9 does not necessarily have to be capable of compressing the mixed gas to a pressure equal to or higher than the required pressure of the gas engine 41 which is the second gas consumer.

[0079] Also in the present embodiment, the same effects as those of the first embodiment can be obtained.

[0080] <Third Embodiment> FIG. 3 is a schematic configuration diagram of a gas supply system 1C according to the third embodiment. In the gas supply system 1C according to the third embodiment, unlike the gas supply system 1A according to the first embodiment, the second supply line 20 does not include the first branch flow path 22. That is, the gas compressed by the first compressor 7 is guided to the boiler 4, and the gas compressed by the second compressor 9 is guided to the gas engine 41. The second compressor 9 can compress the mixed gas to a pressure equal to or higher than the required pressure of the gas engine 41, which is the second gas consumer. The second compressor 9 does not necessarily have to compress the mixed gas to a pressure equal to or higher than the required pressure of the boiler 4, which is the first gas consumer.

[0081] Also in this embodiment, the same effects as those in the first embodiment can be obtained.

[0082] <Fourth Embodiment> FIG. 4 is a schematic configuration diagram of a gas supply system 1D according to the fourth embodiment. In the gas supply system 1D according to the fourth embodiment, unlike the gas supply system 1A according to the first embodiment, in addition to the gas engine 41 which is the second gas consumer, a GCU 81 that can consume the supplied gas regardless of whether the gas is compressed is provided.

[0083] The second supply line 20 includes, in addition to the common flow path 21, the first branch flow path 22, and the second branch flow path 23. The first branch flow path 22, the second branch flow path 23, and the third branch flow path 82 branch at a branch point 20b which is the downstream end of the common flow path 21. The downstream end 20e of the third branch flow path 82 is connected to the gas combustion device 81. Also, an on-off valve 83 that can open and close the flow path is arranged in the third branch flow path 82.

[0084] Further, the gas supply system 1D includes a bypass line 84 that guides the gas discharged from the tank 2 to the GCU 81 bypassing the first compressor 7 and the second compressor 9. The upstream end of the bypass line 84 is connected to a portion upstream of the on-off valve 24 in the common flow path 21, and the downstream end of the bypass line 84 is connected to a portion between the on-off valve 83 and the GCU 81 in the third branch flow path 82.

[0085] Also in this embodiment, the same effects as those of the first embodiment can be obtained. Further, in this embodiment, when the total supply of hydrogen gas to both the boiler 4 and the gas engine 41 exceeds the total consumption of hydrogen gas of both the boiler 4 and the gas engine 41, surplus hydrogen gas can be supplied to the GCU 81 through the third branch flow path 82. Further, in this embodiment, the gas discharged from the tank 2 can be guided to the GCU 81 through the bypass line 84 without passing through the first compressor 7 or the second compressor 9.

[0086] <Other Embodiments> The present disclosure is not limited to the above-described embodiments, and various modifications are possible without departing from the gist of the present disclosure.

[0087] For example, in the above embodiment, a hydrogen carrier ship that transports liquefied hydrogen as cargo is exemplified as an example of a ship, but the ship is not limited thereto. For example, the ship may be a hydrogen fuel ship that uses hydrogen gas as a propulsion fuel. In this case, the hydrogen fuel ship may be a cargo ship that transports cargo other than liquefied hydrogen, or a passenger ship. Further, the ship may be an offshore floating facility.

[0088] Further, although the gas supply system of the above embodiment is mounted on a ship, the gas supply system may be provided in onshore facilities. For example, the gas supply system may be provided in a liquefied hydrogen production plant, a liquefied hydrogen storage facility, a liquefied hydrogen transportation facility, a liquefied hydrogen loading base, etc. provided on land.

[0089] The shape of the tank is not particularly limited, and it may be spherical, horizontally cylindrical, or rectangular. Also, the type of the tank is not particularly limited, for example, a membrane type, a self-supporting sphere type, etc.

[0090] In the above embodiment, each of the first gas consumer and the second gas consumer may be for propulsion or power generation, or for another use. In the above embodiment, the boiler 4 is described as the gas consumer or the first gas consumer, but the gas consumer or the first gas consumer may not be a boiler, and may be a gas engine capable of using hydrogen gas as a fuel gas. The gas engine may not be a dual fuel engine, and may be a gas dedicated combustion engine that uses only the fuel gas as fuel. The gas consumer or the first gas consumer may not be a main machine, but may be an auxiliary machine. The gas consumer or the first gas consumer may be a power generation facility.

[0091] In the above embodiment, the gas engine 41 for power generation is described as the second gas consumer, but the second gas consumer may not be a gas engine for power generation. For example, the second gas consumer may be a boiler capable of using hydrogen gas as a fuel gas.

[0092] The gas supply system may include a plurality of second gas consumers. In this case, the types of the plurality of second gas consumers may be different from each other.

[0093] Also, the opening and closing timings of the valves 15, 16, 17, 24, 25, 26, 33, 64, 65, 66, 72 in the gas replacement are not limited to those described in the above embodiment. For example, in the above embodiment, in the navigation from the loading area to the unloading area, the on-off valves 24, 26 were closed, but the on-off valves 24, 26 may be opened while maintaining the on-off valve 25 in the closed state. In this case, hydrogen gas may be introduced into the second compressor 9, the hydrogen gas may be pressurized to a pressure equal to or higher than the required pressure of the second gas consumer 41, and the hydrogen gas may be consumed by the second gas consumer 41.

[0094] The valves 15, 16, 17, 24, 25, 26, 33, 64, 65, 66, 72 described in the above embodiments were all described as on-off valves, but the valves provided in each flow path are not limited to on-off valves. In the flow paths provided with the respective valves 15, 16, 17, 24, 25, 26, 33, 64, 65, 66, 72 provided in each flow path, a pressure regulating valve or a flow rate control valve may be provided instead of or in addition to the on-off valve. For example, when the required pressure of the second gas consumer is different from the required pressure of the first gas consumer, the valve provided in the portion between the downstream end 20c and the branch point 20b in the second supply line 20 (the first branch flow path 22) may be a valve that can adjust the pressure of the hydrogen gas supplied to the second gas consumer to the required pressure of the second gas consumer that has been reduced from the required pressure of the first gas consumer.

[0095] The connection mode of the second supply line to the first supply line is not limited to that described in the above embodiments. The second supply line may be a line that bypasses the first compressor, guides gas from the tank to the second compressor, and guides the gas compressed by the second compressor to a gas consumer (the first gas consumer or the second gas consumer) by bypassing the first compressor.

[0096] For example, the second supply line may be composed of a plurality of flow paths separated from each other. For example, the second supply line may branch from an upstream portion of the first compressor in the first supply line and merge into a downstream portion of the first compressor in the first supply line, that is, a bypass line that bypasses the first compressor and a line on which the second compressor is arranged that branches from the first supply line at a location different from the connection location of the bypass line. That is, the second compressor may not be arranged on the bypass line that bypasses the first compressor. FIGS. 5 and 6 show examples of gas supply systems in which the second supply line is composed of a plurality of flow paths separated from each other as Modifications 1 and 2, respectively.

[0097] The gas supply system 1E shown in Fig. 5 includes a gas consumer 101 that can consume hydrogen gas, a tank 102 that stores hydrogen gas, a first supply line 103 that connects the tank 102 and the gas consumer 101, a first compressor 104 that is arranged in the first supply line 103 and is configured to compress the hydrogen gas discharged from the tank 102 to a pressure equal to or higher than the required pressure of the gas consumer 103, an inert gas line 105 that guides an inert gas to the tank 102, a second supply line 106, and a second compressor 107 that is configured to compress the mixed gas of the inert gas and the hydrogen gas, which is discharged from the tank 102 when the inert gas is guided to the tank 102 through the inert gas line 105, to a pressure equal to or higher than the required pressure of the gas consumer 101. As shown in Fig. 5, the second supply line 106 includes a first sub-line 106a and a second sub-line 106b. The first sub-line 106a branches from an upstream portion of the first supply line 103 with respect to the first compressor 104 and is connected to a downstream portion of the first supply line 103 with respect to the first compressor 104. That is, the first sub-line 106a is a line that bypasses the first compressor 104. The second sub-line 106b branches from a downstream portion of the first supply line 103 at a connection point with the first sub-line 106a and merges with the first supply line 103 further downstream. The second sub-line 106b may be connected (branched and merged) to the first supply line 103 in an upstream portion with respect to two connection points with the first sub-line 106a. The second compressor 107 is arranged in the second sub-line 106b. Also in this example, it is possible to selectively use the compressors according to the application.

[0098] The gas supply system 1F shown in FIG. 6 includes a first gas consumer 201 that can consume hydrogen gas, a tank 202 that stores hydrogen gas, a first supply line 203 that connects the tank 202 and the first gas consumer 201, a first compressor 204 that is disposed in the first supply line 203 and is configured to compress the hydrogen gas discharged from the tank 202 to a pressure equal to or higher than the required pressure of the first gas consumer 203, an inert gas line 205 that guides an inert gas to the tank 202, a second gas consumer 208 that can consume a mixed gas of the inert gas and the hydrogen gas, a second supply line 206, and a second compressor 207 that is configured to compress the mixed gas of the inert gas and the hydrogen gas discharged from the tank 202, due to the inert gas being guided to the tank 202 by the inert gas line 205, to a pressure equal to or higher than the required pressure of the first gas consumer 201. As shown in FIG. 6, the second supply line 206 includes a first sub-line 206a and a second sub-line 206b. The first sub-line 206a branches from an upstream portion of the first supply line 203 with respect to the first compressor 204 and merges into a downstream portion of the first supply line 203 with respect to the first compressor 204. The second sub-line 206b branches from the merging point of the first sub-line 206a in the first supply line 203 and leads to the second gas consumer 208. The first sub-line 206a is a line that bypasses the first compressor 204. The second compressor 207 is disposed in the second sub-line 206b. Also in this example, it is possible to selectively use the compressors according to the application.

[0099] In the above-described embodiment, the hydrogen line 60 was connected to the first supply line 10 and the inert gas line 32, but the hydrogen line 60 is not limited to such a configuration. For example, the first branch flow path 62 of the hydrogen line 60 may be directly connected to the tank 2 without passing through the first supply line 10. That is, one end of the first branch flow path 62 may be disposed above the tank 2. Further, for example, the second branch flow path 63 of the hydrogen line 60 may be directly connected to the tank 2 without passing through the inert gas line 32. That is, one end of the second branch flow path 63 may be disposed below the tank 2. Also, the hydrogen line 60 was a line used in both the case of supplying hydrogen gas to the tank 2 and the case of supplying liquefied hydrogen to the tank 2, but the hydrogen line 60 may separately include a gas line for supplying hydrogen gas to the tank 2 and a liquid line for supplying liquefied hydrogen to the tank 2.

[0100] The above-described first to fourth embodiments, other embodiments, and modification examples 1 and 2 can be appropriately combined. For example, the second supply line shown in modification examples 1 and 2 may be applied to each of the above-described first to fourth embodiments.

[0101] The functions of the elements disclosed in this specification can be executed using a circuit or processing circuit including a general-purpose processor, a dedicated processor, an integrated circuit, an ASIC (Application Specific Integrated Circuits), a conventional circuit, and / or a combination thereof that is configured or programmed to execute the disclosed functions. Since a processor includes transistors and other circuits, it is regarded as a processing circuit or a circuit. In the present disclosure, a circuit, a unit, or a means is hardware that executes the listed functions or hardware that is programmed to execute the listed functions. The hardware may be the hardware disclosed in this specification or other known hardware that is programmed or configured to execute the listed functions. When the hardware is a processor considered to be a type of circuit, the circuit, means, or unit is a combination of hardware and software, and the software is used for the configuration of the hardware and / or the processor.

[0102] [Disclosed Item] Each of the following items is a disclosure of a preferred embodiment.

[0103] [Item 1] A gas consumer capable of consuming hydrogen gas, A tank for storing hydrogen gas, A first supply line connecting the tank and the gas consumer, A first compressor disposed in the first supply line and configured to compress the hydrogen gas discharged from the tank and guided by the first supply line to a pressure equal to or higher than the required pressure of the gas consumer, An inert gas line for guiding an inert gas to the tank, A second supply line connected to an upstream portion of the first supply line with respect to the first compressor and connected to a downstream portion of the first supply line with respect to the first compressor, A second compressor arranged in the second supply line and configured to be able to compress a mixed gas of the inert gas and the hydrogen gas, which is discharged from the tank when the inert gas is introduced into the tank through the inert gas line, to a pressure equal to or higher than the required pressure of the gas consumer. A gas supply system comprising the same. According to Item 1, in addition to the first compressor for pumping off boil-off gas, a second compressor capable of compressing a mixed gas of an inert gas and hydrogen gas to a pressure equal to or higher than the required pressure of the boiler is provided. Therefore, it is possible to selectively use the compressors according to the application, reliably suppress the pressure rise in the tank, and efficiently replace the hydrogen gas in the tank during gas replacement.

[0104] [Item 2] The gas supply system according to Item 1, wherein the gas consumer is a boiler. Depending on the type of gas consumer, there are some that cannot consume the mixed gas unless the proportion of hydrogen gas in the mixed gas is a certain level or higher. However, according to Item 2, since the gas consumer is a boiler, the mixed gas can be consumed regardless of the mixing ratio of hydrogen gas and inert gas.

[0105] [Item 3] A second gas consumer of a type different from the first gas consumer, which is the gas consumer capable of consuming the mixed gas, A branch flow path that branches from a downstream portion of the second compressor in the second supply line or branches from a downstream portion of the first compressor in the first supply line and is connected to the second gas consumer. The gas supply system according to Item 1 or 2 further comprises the same. According to Item 3, even when the supply amount of hydrogen gas compressed by the first compressor and supplied to the first gas consumer exceeds the consumption amount of hydrogen gas in the first gas consumer, the excess hydrogen gas between the first compressor and the first gas consumer in the first supply line is guided to the second gas consumer through the branch flow path, and the second gas consumer can effectively utilize the hydrogen gas.

[0106] [Item 4] A first gas consumer capable of consuming hydrogen gas, A tank for storing hydrogen gas, A first supply line connecting the tank and the first gas consumer, A first compressor disposed in the first supply line, configured to compress the hydrogen gas discharged from the tank and guided by the first supply line to a pressure equal to or higher than the required pressure of the first gas consumer, An inert gas line for guiding an inert gas to the tank, A second gas consumer capable of consuming a mixed gas of the inert gas and the hydrogen gas, A second supply line connected to an upstream portion of the first compressor in the first supply line and connected to the second gas consumer, A second compressor disposed in the second supply line, configured to compress the mixed gas discharged from the tank when the inert gas is guided to the tank by the inert gas line to a pressure equal to or higher than the required pressure of the second gas consumer, A gas supply system comprising: According to Item 4, a second compressor capable of compressing a mixed gas of an inert gas and hydrogen gas to a pressure equal to or higher than the required pressure of a boiler is provided separately from the first compressor for pumping boil-off gas. Therefore, it is possible to use the compressors appropriately according to the application, reliably suppress the pressure rise in the tank, and efficiently perform the replacement of the hydrogen gas in the tank during gas replacement.

[0107] [Item 5] A ship comprising the gas supply system according to any one of Items 1 to 4. Since a second compressor for pumping a mixed gas is mounted on the ship separately from the first compressor for pumping boil-off gas, for example, when the ship sails towards the dock for maintenance work, gas replacement for replacing the hydrogen gas in the tank with an inert gas can be performed. In addition, a mixed gas of an inert gas and hydrogen gas can be effectively utilized in a propulsion boiler.

[0108] [Item 6] A gas supply method for supplying the gas discharged from the tank, When discharging hydrogen gas from the tank in a state where hydrogen gas is stored, the hydrogen gas discharged from the tank is guided to a first compressor and compressed, the compressed hydrogen gas is consumed by a first gas consumer, when discharging a mixed gas in which an inert gas and hydrogen gas are mixed from the tank, the mixed gas discharged from the tank is guided to a second compressor of a type different from the first compressor and compressed, the compressed mixed gas is consumed by the first gas consumer or a second gas consumer of a type different from the first gas consumer, a gas supply method. The inert gas has a much larger specific gravity than hydrogen gas. When using a compressor for hydrogen gas also for compressing the mixed gas during gas replacement, there is a risk that the performance required for the compressor for hydrogen gas becomes too high or that the compressor for hydrogen gas is overloaded by compressing the mixed gas. However, according to the method of item 6, the compressors used are properly selected depending on whether it is the case of compressing the hydrogen gas discharged from the tank or the case of compressing the mixed gas discharged from the tank during gas replacement. For this reason, it is possible to avoid the situation where the performance required for the hydrogen gas compressor becomes too high or the hydrogen gas compressor is overloaded by compressing the mixed gas.

[0109] [Item 7] Discharging hydrogen gas from the tank in a state where hydrogen gas is stored includes discharging hydrogen gas from the tank without supplying an inert gas to the tank in a state where hydrogen gas is stored, Discharging the mixed gas from the tank includes discharging the mixed gas from the tank by supplying an inert gas to the tank in a state where hydrogen gas is stored, the gas supply method according to item 6. It is possible to properly select the compressors used depending on whether it is the case of compressing the gas discharged from the tank when performing gas replacement to replace the hydrogen gas in the tank with an inert gas or the case of compressing the gas discharged from the tank when not performing gas replacement.

[0110] [Item 8] The tank, the first compressor, the first gas consumer, the second compressor, and the second gas consumer are mounted on a ship, Discharging hydrogen gas from the tank in a state of containing hydrogen gas includes discharging hydrogen gas, which is boil-off gas generated by evaporation of liquefied hydrogen in the tank, from the tank while the ship is navigating toward a discharging place for discharging the liquefied hydrogen stored in the tank, Discharging the mixed gas from the tank to perform the gas replacement is the gas supply method according to Item 7, which is performed while the ship is berthed at the discharging place or while the ship is navigating from the discharging place after discharging the liquefied hydrogen in the tank at the discharging place. For ships that cannot perform gas replacement operations on board, it is necessary to return the mixed gas to land after landing, and it is not possible to smoothly shift to maintenance work. On the other hand, according to Item 8, it is possible to smoothly shift to maintenance work by promoting gas replacement during navigation while effectively using the hydrogen gas in the tank replaced with the inert gas.

[0111] [Item 9] Discharging hydrogen gas from the tank in a state of containing hydrogen gas includes discharging hydrogen gas from the tank without supplying an inert gas to the tank in a state of containing hydrogen gas, Discharging the mixed gas from the tank includes discharging the mixed gas from the tank by supplying hydrogen gas to the tank in a state of containing an inert gas, and is the gas supply method according to any one of Items 6 to 8. The compressors used can be properly selected between the case of compressing the gas discharged from the tank when performing gas replacement to replace the inert gas in the tank with hydrogen gas and the case of compressing the gas discharged from the tank when not performing gas replacement.

Claims

1. A gas consumer capable of consuming hydrogen gas, A tank for storing hydrogen gas, A first supply line connecting the tank and the gas consumer, A first compressor disposed in the first supply line and configured to compress the hydrogen gas discharged from the tank and guided by the first supply line to a pressure equal to or higher than the required pressure of the gas consumer, An inert gas line for guiding an inert gas to the tank, A second supply line connected to an upstream portion of the first compressor in the first supply line and connected to a downstream portion of the first compressor in the first supply line, A second compressor disposed in the second supply line and configured to compress the mixed gas of the inert gas and the hydrogen gas discharged from the tank due to the introduction of the inert gas into the tank by the inert gas line to a pressure equal to or higher than the required pressure of the gas consumer, A gas supply system comprising the above.

2. The gas supply system according to claim 1, wherein the gas consumer is a boiler.

3. A second gas consumer of a type different from the first gas consumer capable of consuming the mixed gas, A branch flow path branching from a downstream portion of the second compressor in the second supply line or branching from a downstream portion of the first compressor in the first supply line and connected to the second gas consumer, further comprising the gas supply system according to claim 1 or 2.

4. A first gas consumer capable of consuming hydrogen gas, A tank for storing hydrogen gas, A first supply line connecting the tank and the first gas consumer, A first compressor disposed in the first supply line and configured to compress the hydrogen gas discharged from the tank and guided by the first supply line to a pressure equal to or higher than the required pressure of the first gas consumer, An inert gas line for guiding an inert gas to the tank, A second gas consumer capable of consuming the mixed gas of the inert gas and the hydrogen gas, A second supply line connected to an upstream portion of the first compressor in the first supply line and connected to the second gas consumer, A second compressor disposed in the second supply line and configured to compress the mixed gas discharged from the tank due to the introduction of the inert gas into the tank by the inert gas line to a pressure equal to or higher than the required pressure of the second gas consumer, A gas supply system comprising the above.

5. A ship comprising the gas supply system according to claim 1 or 4.

6. A gas supply method for supplying gas discharged from a tank, comprising: when discharging hydrogen gas from the tank in a state of containing hydrogen gas, guiding the hydrogen gas discharged from the tank to a first compressor and compressing it, consuming the compressed hydrogen gas by a first gas consumer, when discharging a mixed gas of an inert gas and hydrogen gas from the tank, guiding the mixed gas discharged from the tank to a second compressor of a type different from the first compressor and compressing it, A gas supply method for consuming the compressed mixed gas by the first gas consumer or a second gas consumer of a type different from the first gas consumer.

7. Discharging hydrogen gas from the tank in a state of containing hydrogen gas includes discharging hydrogen gas from the tank without supplying an inert gas to the tank in a state of containing hydrogen gas, Discharging the mixed gas from the tank includes discharging the mixed gas from the tank by supplying an inert gas to the tank in a state of containing hydrogen gas. The gas supply method according to claim 6.

8. The tank, the first compressor, the first gas consumer, the second compressor, and the second gas consumer are mounted on a ship, Discharging hydrogen gas from the tank in a state of containing hydrogen gas includes discharging, as boil-off gas generated by evaporation of liquefied hydrogen in the tank, the hydrogen gas from the tank while navigating the ship toward a discharging place for unloading the liquefied hydrogen stored in the tank, Discharging the mixed gas from the tank for gas replacement is performed while the ship is moored at the discharging place or during navigation of the ship from the discharging place after unloading the liquefied hydrogen in the tank at the discharging place. The gas supply method according to claim 7.

9. Discharging hydrogen gas from the tank in a state of containing hydrogen gas includes discharging hydrogen gas from the tank without supplying an inert gas to the tank in a state of containing hydrogen gas, Discharging the mixed gas from the tank includes discharging the mixed gas from the tank by supplying hydrogen gas to the tank in a state of containing an inert gas. The gas supply method according to claim 6 or 7.

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