Fuel cell system and fuel cell ship

Abstract

To reduce influence of a decrease in fuel concentration due to the mixture of an inert gas on power generation of a fuel cell.SOLUTION: A fuel cell system 5 includes: a fuel cell 51 that supplies power to a propulsion device 9 or an auxiliary machine 11; a fuel gas pipe 41 through which a fuel gas flows; an inert gas pipe 43 that is connected to the fuel gas pipe 41 and into which an inert gas is introduced when the fuel gas is purged; a backflow control unit 31 that is disposed in the inert gas pipe 43 and controls backflow; a flow rate control unit 63 that can adjust a flow rate of the fuel gas; a detection unit 29 that detects the mixture of the inert gas into the fuel gas pipe 41; and a control unit 171 that controls the flow rate control unit 63. In a case where a detection result of the detection unit 29 indicates the mixture of the inert gas when the fuel gas is supplied to the fuel gas pipe 41, the control unit 171 controls the flow rate control unit 63 so that a fuel utilization rate of the fuel cell 51 is reduced.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a fuel cell system and a fuel cell ship. [Background technology]

[0002] The explosion-proof purge gas supply system for ships described in Patent Document 1 comprises a hydrogen source supply pipe, a fuel cell, a compressor, a nitrogen gas generator, and a nitrogen gas purging means. The hydrogen source supply pipe is connected to an onboard storage for explosive substances such as liquefied petroleum gas, liquefied petroleum gas, liquefied natural gas, petroleum products, alcohols, and hydrogen, and is a pipeline for supplying the explosive substances to the fuel cell. The onboard storage stores explosive substances, and therefore requires purging with nitrogen gas to ensure explosion prevention. The fuel cell generates electricity using hydrogen gas. The compressor compresses the nitrogen-rich gas exhausted by the fuel cell. The nitrogen gas generator uses the nitrogen-rich gas discharged by the compressor as a raw material. The nitrogen gas purging means supplies the nitrogen gas generated by the nitrogen gas generator to the onboard storage for explosion prevention purposes. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-225140 A Summary of the Invention [Problem to be solved by the invention]

[0004] In a fuel cell ship driven by a fuel cell, it may be required to purge the fuel gas in the fuel gas tank with an inert gas for maintenance and inspection of the fuel gas tank. Then, the fuel gas is filled into the fuel gas tank after purging.

[0005] However, depending on the internal pressure of the inert gas pipe and the fuel gas pipe, the inert gas remaining in the inert gas pipe may flow into the fuel gas pipe and become mixed into the fuel gas, which may result in a decrease in the fuel concentration of the fuel gas and a decrease in the power generation performance of the fuel cell.

[0006] The present invention has been made in consideration of the above-mentioned problems, and its object is to provide a fuel cell system and a fuel cell ship that can reduce the impact on fuel cell power generation caused by a decrease in fuel concentration due to the inclusion of inert gas. [Means for solving the problem]

[0007] According to one aspect of the present invention, a fuel cell system includes a fuel cell, a fuel gas pipe, an inert gas pipe, a backflow regulation unit, a flow rate adjustment unit, a detection unit, and a control unit. The fuel cell supplies power to a propulsion device that generates a thrust force on a ship body, or to an auxiliary device installed in the ship. The fuel gas pipe allows a fuel gas to be supplied to the fuel cell to flow. The inert gas pipe is connected to the fuel gas pipe, and the inert gas is introduced when the fuel gas is purged with the inert gas. The backflow regulation unit is disposed in the inert gas pipe and regulates the backflow of the inert gas and the fuel gas. The flow rate adjustment unit is capable of adjusting the flow rate of the fuel gas to be supplied to the fuel cell. The detection unit detects that the inert gas has passed through the backflow regulation unit from the inert gas pipe and mixed into the fuel gas in the fuel gas pipe. The control unit controls the flow rate adjustment unit to adjust the flow rate of the fuel gas based on the detection result of the detection unit. When the fuel gas is being supplied to the fuel gas piping, if the detection result of the detection unit indicates that the inert gas has been mixed into the fuel gas, the control unit controls the flow rate adjustment unit so that the fuel utilization rate of the fuel cell is reduced. Effect of the Invention

[0008] According to the present invention, it is possible to provide a fuel cell system and a fuel cell ship that can reduce the effect on power generation of a fuel cell caused by a decrease in fuel concentration due to the inclusion of an inert gas. [Brief description of the drawings]

[0009] [Figure 1] 1 is a diagram showing a schematic configuration of a fuel cell ship according to a first embodiment of the present invention. [Diagram 2] 1 is a block diagram showing a fuel cell system and a fuel gas supply system according to a first embodiment. [Diagram 3] 2 is a flowchart showing a fuel gas regulation method according to the first embodiment. [Figure 4] 10 is a flowchart showing a fuel gas regulation method according to a modified example of the first embodiment. [Diagram 5] FIG. 4 is a block diagram showing a fuel cell system and a fuel gas supply system according to a second embodiment of the present invention. [Figure 6] FIG. 11 is a block diagram showing a fuel cell system and a fuel gas supply system according to a third embodiment of the present invention. [Figure 7] FIG. 11 is a block diagram showing a fuel cell system and a fuel gas supply system according to a fourth embodiment of the present invention. [Figure 8] FIG. 11 is a block diagram showing a fuel cell system and a fuel gas supply system according to a fifth embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference characters and description thereof will not be repeated.

[0011] (Embodiment 1) A fuel cell ship 100 according to a first embodiment of the present invention will be described with reference to Figures 1 to 3. First, the fuel cell ship 100 according to the first embodiment will be described with reference to Figure 1. Figure 1 is a diagram showing a schematic configuration of the fuel cell ship 100.

[0012] 1, the fuel cell ship 100 includes a hull 1, a cabin 3, a fuel cell system 5, a fuel gas supply system 6, a battery system 7, a propulsion device 9, a plurality of auxiliary machines 11, an exhaust fan 13, a duct 15, and a control device 17. The cabin 3 is disposed on the upper surface of the hull 1.

[0013] The control device 17 controls the fuel cell system 5, the fuel gas supply system 6, the storage battery system 7, the propulsion device 9, the multiple auxiliary devices 11, and the exhaust fan 13. The control device 17 is configured, for example, with one or more computers. The computer is, for example, an ECU (Electronic Control Unit). The control device 17 is supplied with power from a battery.

[0014] Specifically, the control device 17 has a control unit 171 and a storage unit 173. The control unit 171 includes a processor such as a CPU (Central Processing Unit). The storage unit 173 includes a storage device and stores data and computer programs. Specifically, the storage unit 173 includes a main storage device such as a semiconductor memory, and an auxiliary storage device such as a semiconductor memory, a solid state drive, and / or a hard disk drive. The storage unit 173 may include removable media. The storage unit 173 corresponds to an example of a non-transitory computer-readable storage medium.

[0015] The processor of the control unit 171 controls the fuel cell system 5, the fuel gas supply system 6, the storage battery system 7, the propulsion device 9, the multiple accessories 11, and the exhaust fan 13 by executing computer programs stored in the storage device of the memory unit 173.

[0016] The fuel cell system 5 functions as a main power source. The fuel cell system 5 consumes fuel gas to generate electric power (specifically, DC power). The fuel cell system 5 supplies electric power to the propulsion device 9, the fuel gas supply system 6, the auxiliary machinery 11, and the exhaust fan 13. The fuel cell system 5 also supplies electric power to the storage battery system 7 for charging the storage battery system 7.

[0017] The fuel gas supply system 6 stores the fuel gas and supplies the fuel gas to the fuel cell system 5.

[0018] The fuel gas is typically hydrogen gas.

[0019] The storage battery system 7 functions as an auxiliary power source. In order to make up for a shortage of power supplied by the fuel cell system 5, the storage battery system 7 supplies stored power (specifically, DC power) to the propulsion device 9, the fuel gas supply system 6, the auxiliary equipment 11, and the exhaust fan 13. The storage battery system 7 may also supply power to the control device 17. The storage battery system 7 has a storage battery. The storage battery is, for example, a lithium secondary battery, a nickel-cadmium storage battery, or a nickel-hydrogen storage battery. Note that a system may be adopted in which the storage battery system 7 is used as a main power source and the fuel cell system 5 is used as a power source for charging the storage battery system 7, that is, the fuel cell system 5 is used as a range extender.

[0020] The propulsion device 9 is driven by electric power and generates a propulsive force for the hull 1. The propulsion device 9 has a power conversion device 91, a propulsion motor 93, and a propeller 95. The power conversion device 91 converts the electric power supplied from the fuel cell system 5 into electric power according to the specifications of the propulsion motor 93. For example, the power conversion device 91 converts DC power into AC power. In this case, for example, the power conversion device 91 has an inverter. The propulsion motor 93 is driven by the electric power (for example, AC power) supplied from the power conversion device 91. When the propulsion motor 93 is driven, the rotational force of the propulsion motor 93 is transmitted to the propeller 95. As a result, the propeller 95 rotates, generating a propulsive force for the hull 1.

[0021] The exhaust fan 13 is driven by electricity and exhausts air from the inside of the hull 1 to the outside through a duct 15.

[0022] The auxiliary equipment 11 is a device driven by electric power and is different from the propulsion device 9 and the control device 17. The auxiliary equipment 11 is, for example, a compressor, an electromagnetic valve, a pump, a lighting device, or an air conditioning device. However, the type of the auxiliary equipment 11 is not particularly limited.

[0023] Next, the fuel cell system 5 and the fuel gas supply system 6 will be described with reference to Fig. 2. Fig. 2 is a block diagram showing the fuel cell system 5 and the fuel gas supply system 6.

[0024] As shown in FIG. 2, the fuel cell ship 100 further includes a fuel gas pipe 41, an inert gas pipe 43, an oxidant gas pipe 45, a pipe 47, a joint JT1, and a joint JT2.

[0025] The fuel cell system 5 includes a fuel cell 51 , a flow rate regulator 53 , and an oxidizing gas supplier 55 .

[0026] For example, the fuel cell 51, the flow rate regulator 53, a portion of the fuel gas pipe 41 (specifically, a portion of the third fuel gas pipe 413), and a portion of the oxidant gas pipe 45 are housed in a fuel cell housing (not shown). The fuel cell housing is, for example, a container, a chamber, or a box. The material of the fuel cell housing is, for example, fiber reinforced plastics (FRP) or an iron plate. The fuel cell housing is, for example, disposed below the deck 1a or on the deck 1a.

[0027] The fuel gas supply system 6 includes a fuel gas inlet 21, a first backflow regulation unit 23, an inert gas inlet 25, an opening / closing unit 27, a detection unit 29, a second backflow regulation unit 31, an opening / closing unit 33, a fuel gas tank 61, and a flow rate adjustment unit 63. The second backflow regulation unit 31 corresponds to an example of the "backflow regulation unit" of the present invention.

[0028] The detection unit 29 includes a first pressure detection unit 291 and a second pressure detection unit 292. The fuel gas tank 61 includes a tank body 611, a valve unit 612, and a temperature detection unit 613. The valve unit 612 includes a backflow prevention unit B1 and an opening / closing unit B2. The flow rate adjustment unit 63 includes a third pressure detection unit 631, a pressure reduction unit 632, and an opening / closing unit 633.

[0029] For example, the second pressure detection unit 292, the fuel gas tank 61, the flow rate adjustment unit 63, and a portion of the fuel gas piping 41 (specifically, a portion of the first fuel gas piping 411 and a portion of the second fuel gas piping 412) are housed in a fuel container (not shown). The fuel container is, for example, a container, a chamber, or a box. The material of the fuel container is, for example, fiber reinforced plastic (FRP) or an iron plate. The fuel container is, for example, disposed below the deck 1a or on the deck 1a.

[0030] Hereinafter, the fuel gas inlet 21 and the inert gas inlet 25 side refer to the upstream side of the gas flow, and the fuel cell 51 side refers to the downstream side of the gas flow. The gas is a fuel gas or an inert gas.

[0031] Next, still referring to FIG. 2, the connection relationship between the fuel gas pipe 41 and the inert gas pipe 43 and the arrangement of each element will be described.

[0032] One end of the fuel gas piping 41 is connected to the fuel gas inlet 21. The other end of the fuel gas piping 41 is connected to the fuel cell 51. Fuel gas to be supplied to the fuel cell 51 flows through the fuel gas piping 41. In the fuel gas piping 41, a first backflow regulation unit 23, a joint JT1, a second pressure detection unit 292, a fuel gas tank 61, a flow rate adjustment unit 63, a joint JT2, and a flow rate adjustment unit 53 are arranged.

[0033] Specifically, the fuel gas pipe 41 includes a first fuel gas pipe 411 , a second fuel gas pipe 412 , and a third fuel gas pipe 413 .

[0034] Fuel gas flows through the first fuel gas pipe 411. One end of the first fuel gas pipe 411 is connected to the fuel gas inlet 21, and the other end of the first fuel gas pipe 411 is connected to the fuel gas tank 61. Thus, the first fuel gas pipe 411 supplies fuel gas to the fuel gas tank 61. Specifically, the other end of the first fuel gas pipe 411 is connected to the backflow regulating section B1 of the fuel gas tank 61.

[0035] The first fuel gas pipe 411 is provided with a first backflow regulation unit 23, a second pressure detection unit 292, and a joint JT1. The first backflow regulation unit 23 is provided between the fuel gas inlet 21 and the joint JT1. In other words, the first backflow regulation unit 23 is provided upstream of the joint JT1. For example, the first backflow regulation unit 23 is provided near the fuel gas inlet 21. The second pressure detection unit 292 is provided between the joint JT1 and the opening / closing unit B2 of the fuel gas tank 61.

[0036] Fuel gas flows through the second fuel gas pipe 412. One end of the second fuel gas pipe 412 is connected to the fuel gas tank 61, and the other end of the second fuel gas pipe 412 is connected to one end of the third fuel gas pipe 413 via a joint JT2. Therefore, the second fuel gas pipe 412 supplies fuel gas from the fuel gas tank 61 to the fuel cell 51 via the third fuel gas pipe 413. Specifically, one end of the second fuel gas pipe 412 is connected to the opening / closing section B2 of the fuel gas tank 61, and the other end of the second fuel gas pipe 412 is connected to the joint JT2.

[0037] A flow rate adjuster 63 is disposed in the second fuel gas piping 412. Specifically, the third pressure detection unit 631, the pressure reduction unit 632, and the opening / closing unit 633 of the flow rate adjuster 63 are disposed in the second fuel gas piping 412 between the opening / closing unit B2 of the fuel gas tank 61 and the joint JT2. More specifically, the third pressure detection unit 631, the pressure reduction unit 632, and the opening / closing unit 633 of the flow rate adjuster 63 are disposed in the second fuel gas piping 412 in the order of the third pressure detection unit 631, the pressure reduction unit 632, and the opening / closing unit 633 from upstream to downstream.

[0038] Fuel gas flows through the third fuel gas pipe 413. One end of the third fuel gas pipe 413 is connected to a joint JT2. That is, one end of the third fuel gas pipe 413 is connected to the other end of the second fuel gas pipe 412 via the joint JT2, and the other end of the third fuel gas pipe 413 is connected to the fuel cell 51. A flow rate regulator 53 is disposed in the third fuel gas pipe 413. The third fuel gas pipe 413 supplies fuel gas from the fuel gas tank 61 and the second fuel gas pipe 412 to the fuel cell 51 (specifically, the anode).

[0039] An oxidizing gas flows through the oxidizing gas pipe 45. The oxidizing gas pipe 45 connects an oxidizing gas supply unit 55 and the fuel cell 51. Therefore, the oxidizing gas pipe 45 supplies the oxidizing gas from the oxidizing gas supply unit 55 to the fuel cell 51 (specifically, the cathode).

[0040] Typically, the oxidant gas is air and the oxidant is oxygen.

[0041] An inert gas flows through the inert gas pipe 43. Specifically, the inert gas is introduced into the inert gas pipe 43 at a time period different from the time period during which the fuel gas is introduced from the fuel gas inlet 21 into the fuel gas pipe 41. More specifically, the inert gas is introduced into the inert gas pipe 43 when the fuel gas is purged with the inert gas. This point will be described in detail later.

[0042] Typically the inert gas is nitrogen.

[0043] One end of the inert gas pipe 43 is connected to the inert gas inlet 25, and the other end of the inert gas pipe 43 is connected to the fuel gas pipe 41 via a joint JT1. Specifically, the other end of the inert gas pipe 43 is connected to the first fuel gas pipe 411 via the joint JT1. That is, the other end of the inert gas pipe 43 is connected to the joint JT1. The joint JT1 is a connection point between the inert gas pipe 43 and the fuel gas pipe 41 (specifically, the first fuel gas pipe 411).

[0044] The inert gas pipe 43 is provided with an opening / closing unit 27, a first pressure detection unit 291, and a second backflow regulation unit 31. Specifically, the opening / closing unit 27, the first pressure detection unit 291, and the second backflow regulation unit 31 are disposed between the inert gas inlet 25 and the joint JT1 in the inert gas pipe 43. More specifically, the opening / closing unit 27, the first pressure detection unit 291, and the second backflow regulation unit 31 are disposed in the inert gas pipe 43 from upstream to downstream in this order: opening / closing unit 27, first pressure detection unit 291, and second backflow regulation unit 31.

[0045] The opening / closing unit 27, the first pressure detection unit 291, and the second backflow regulation unit 31 are disposed upstream of the joint JT1. The opening / closing unit 27 is disposed, for example, near the inert gas inlet 25. The opening / closing unit 27 and the first pressure detection unit 291 are disposed upstream of the second backflow regulation unit 31. The first pressure detection unit 291 is disposed between the opening / closing unit 27 and the second backflow regulation unit 31.

[0046] The pipe 47 is connected to the joint JT2. Therefore, the pipe 47 is connected to the fuel gas pipe 41 via the joint JT2. Specifically, the pipe 47 is connected to the second fuel gas pipe 412 and the third fuel gas pipe 413 via the joint JT2. The opening and closing unit 33 is disposed on the pipe 47.

[0047] Next, the operation of the fuel cell system 5 will be described with continued reference to Fig. 2. The fuel cell 51 generates electric power (specifically, DC power) through an electrochemical reaction between a fuel gas and an oxidant gas.

[0048] The fuel cell 51 supplies electric power to the propulsion device 9, the fuel gas supply system 6, the exhaust fan 13, and the auxiliary machinery 11. Note that the fuel cell 51 may supply electric power to the propulsion device 9, the fuel gas supply system 6, the exhaust fan 13, and the auxiliary machinery 11 indirectly via a circuit such as a DC / DC converter.

[0049] Specifically, the fuel cell 51 is a fuel cell stack composed of a plurality of stacked cells. For example, each cell of the fuel cell 51 has a solid polymer electrolyte membrane, an anode, a cathode, and a pair of separators. The anode and the cathode sandwich the solid polymer electrolyte membrane. The anode is a negative electrode (fuel electrode). The anode includes an anode catalyst layer and a gas diffusion layer. The cathode is a positive electrode (air electrode). The cathode includes a cathode catalyst layer and a gas diffusion layer. The anode, the solid polymer electrolyte membrane, and the cathode form a membrane electrode assembly (MEA: Membrane Electrode Assembly). The pair of separators sandwich the membrane electrode assembly. Each separator has a plurality of grooves. Each groove of one separator forms a flow path for fuel gas. Each groove of the other separator forms a flow path for oxidant gas.

[0050] The flow rate adjuster 53 opens or closes the flow path of the fuel gas pipe 41 (specifically, the third fuel gas pipe 413). Specifically, the flow rate adjuster 53 switches between supplying and stopping the supply of fuel gas to the fuel cell 51. Thus, the flow rate adjuster 53 can cut off the fuel gas supplied to the fuel cell 51. Typically, the flow rate adjuster 53 is an on-off valve.

[0051] The fuel gas pipe 41 (specifically, the third fuel gas pipe 413) guides the fuel gas that has passed through the flow rate regulator 53 to the fuel cell 51 (specifically, the anode).

[0052] The oxidizing gas supply unit 55 supplies the oxidizing gas to the fuel cell 51 (specifically, the cathode). Typically, the oxidizing gas supply unit 55 is an air compressor, which compresses the oxidizing gas and supplies the compressed oxidizing gas to the fuel cell 51.

[0053] The oxidizing gas pipe 56 guides the compressed oxidizing gas supplied from the oxidizing gas supply unit 55 to the fuel cell 51 (specifically, the cathode).

[0054] Next, the operation of the fuel gas supply system 6 will be described with continued reference to FIG. 2. The first backflow regulation unit 23 regulates the backflow of fuel gas. Backflow refers to the flow of fuel gas in the direction toward the fuel gas inlet 21, that is, in the reverse direction. The first backflow regulation unit 23 is typically a check valve. For example, the fuel gas inlet 21 and the first backflow regulation unit 23 are integrated to form a receptacle.

[0055] The opening / closing unit 27 opens or closes the flow path of the inert gas pipe 43 on the upstream side of the inert gas pipe 43. The opening / closing unit 27 is disposed, for example, in the vicinity of the inert gas inlet 25. The opening / closing unit 27 is typically an opening / closing valve.

[0056] The first pressure detection unit 291 detects the internal pressure of the inert gas pipe 43 (hereinafter, referred to as "internal pressure P1") at a position downstream of the opening / closing unit 27 and upstream of the second backflow regulation unit 31. The internal pressure P1 indicates the pressure in the flow path of the inert gas pipe 43. Specifically, the first pressure detection unit 291 detects the internal pressure P1 of the pipe 431 of the inert gas pipe 43. The pipe 431 is the pipe between the opening / closing unit 27 and the second backflow regulation unit 31 of the inert gas pipe 43. Therefore, specifically, the internal pressure P1 of the inert gas pipe 43 indicates the internal pressure of the pipe 431. Then, the first pressure detection unit 291 outputs a signal indicating the internal pressure P1 to the control unit 171. The first pressure detection unit 291 is typically a pressure sensor.

[0057] Hereinafter, the pipe 431 of the inert gas pipe 43 may be referred to as the "inert gas pipe 431".

[0058] The second backflow regulation section 31 regulates the backflow of the inert gas and fuel gas at a position upstream of the joint JT1. Backflow indicates that the inert gas and fuel gas flow in a reverse direction BW. The reverse direction BW indicates the direction from the second backflow regulation section 31 toward the inert gas inlet 25. On the other hand, forward flow indicates that the inert gas flows in a forward direction FW. The forward direction FW indicates the direction from the inert gas inlet 25 toward the second backflow regulation section 31. The second backflow regulation section 31 is typically a check valve.

[0059] The second pressure detection unit 292 detects the internal pressure of the fuel gas pipe 41 (hereinafter, referred to as "internal pressure P2") at a position downstream of the joint JT1. The internal pressure P2 indicates the pressure in the flow path of the fuel gas pipe 41. Specifically, the internal pressure P2 of the fuel gas pipe 41 is the internal pressure of the first fuel gas pipe 411. That is, the internal pressure P2 indicates the pressure in the flow path of the first fuel gas pipe 411. Therefore, the second pressure detection unit 292 detects the internal pressure P2 of the first fuel gas pipe 411. Then, the second pressure detection unit 292 outputs a signal indicating the internal pressure P2 to the control unit 171. The second pressure detection unit 292 is typically a pressure sensor. Note that, as long as the second pressure detection unit 292 can detect the internal pressure P2 of the first fuel gas pipe 411, the arrangement of the second pressure detection unit 292 is not particularly limited. For example, the second pressure detection unit 292 may detect the internal pressure P2 at a position between the second backflow regulation unit 31 and the joint JT1 in the inert gas piping 43. For example, the second pressure detection unit 292 may detect the internal pressure P2 at a position between the first backflow regulation unit 23 and the joint JT1 in the first fuel gas piping 411.

[0060] The fuel gas tank 61 stores the fuel gas. Specifically, the tank body 611 stores the fuel gas. The backflow regulating unit B1 regulates the backflow of the fuel gas stored in the tank body 611 at the inlet of the tank body 611. Backflow indicates that the fuel gas flows from the tank body 611 to the first fuel gas pipe 411. The backflow regulating unit B1 is typically a check valve. The opening / closing unit B2 opens or closes the outlet flow path of the tank body 611. That is, the opening / closing unit B2 switches between introduction and stop of the fuel gas from the tank body 611 to the second fuel gas pipe 412 at the outlet of the tank body 611. The opening / closing unit B2 is typically an opening / closing valve. The temperature detecting unit 613 detects the temperature of the fuel gas stored in the tank body 611 and outputs a signal indicating the temperature to the control unit 171. The temperature detecting unit 613 is typically a temperature sensor.

[0061] The flow rate regulator 63 can regulate the flow rate of the fuel gas supplied to the fuel cell 51. That is, the flow rate regulator 63 regulates the flow rate of the fuel gas supplied from the fuel gas tank 61, and supplies the fuel gas to the fuel cell 51 via the third fuel gas pipe 413. Specifically, the flow rate regulator 63 closes the flow path of the second fuel gas pipe 412 with the opening / closing unit 633, thereby reducing the flow rate of the fuel gas supplied to the fuel cell 51 to zero. Alternatively, the flow rate regulator 63 opens the flow path of the second fuel gas pipe 412 with the opening / closing unit 633, thereby reducing the flow rate of the fuel gas supplied to the fuel cell 51 to a predetermined flow rate.

[0062] Specifically, in the flow rate regulator 63, the third pressure detector 631 detects the internal pressure of the second fuel gas pipe 412 (hereinafter referred to as "internal pressure P3"). The internal pressure P3 indicates the pressure in the flow path of the second fuel gas pipe 412. Then, the third pressure detector 631 outputs a signal indicating the internal pressure P3 to the controller 171. The third pressure detector 631 is typically a pressure sensor.

[0063] The control unit 171 controls the pressure reduction unit 632 based on the internal pressure P3 of the second fuel gas pipe 412. Then, the pressure reduction unit 632 adjusts the pressure of the fuel gas supplied from the fuel gas tank 61. For example, the pressure reduction unit 632 reduces the pressure of the fuel gas supplied from the fuel gas tank 61. Therefore, the flow rate adjustment unit 63 can be considered as a "pressure adjustment unit."

[0064] The pressure reducing unit 632 also functions as a relief valve. That is, the pressure reducing unit 632 opens when the internal pressure P3 of the second fuel gas pipe 412 becomes equal to or higher than a set value, thereby adjusting the internal pressure P3 of the second fuel gas pipe 412 so that it does not become too high. The pressure reducing unit 632 is typically a pressure reducing valve integrated with a relief valve. Note that the pressure reducing unit 632 may be a pressure reducing valve, and a relief valve may be provided separately from the pressure reducing unit 632.

[0065] The opening / closing unit 633 opens or closes the flow path of the second fuel gas pipe 412. In other words, the opening / closing unit 633 switches between supplying and stopping the supply of fuel gas to the fuel cell 51. The opening / closing unit 633 is typically an opening / closing valve.

[0066] Next, still referring to Fig. 2, the operation of filling the fuel gas tank 61 with fuel gas will be described. When filling the fuel gas tank 61 with fuel gas, inert gas is not supplied to the inert gas inlet 25. In this case, the opening / closing unit 27 closes the flow path of the inert gas piping 43. Also, the opening / closing unit B2 of the fuel gas tank 61 closes the outlet flow path of the tank body 611. The states of the opening / closing unit 633, the flow rate adjusting unit 53, and the opening / closing unit 33 are not particularly limited, and may be open or closed.

[0067] When filling the fuel gas tank 61 with fuel gas, high-pressure fuel gas is supplied to the fuel gas inlet 74 without supplying inert gas to the inert gas inlet 25. The pressure of the fuel gas in this case is, for example, 82 MPa. As a result, the fuel gas passes through the first backflow regulation unit 23, the first fuel gas pipe 411, and the backflow regulation unit B1 and is filled into the fuel gas tank 61.

[0068] For example, first, a valve (not shown) disposed in the first fuel gas pipe 411 may be closed, and high-pressure fuel gas may be filled into the first fuel gas pipe 411 from the fuel gas inlet 21. Next, the valve may be opened to fill the fuel gas from the first fuel gas pipe 411 into the fuel gas tank 61. In this case, for example, the valve is disposed in the first fuel gas pipe 411 near the fuel gas tank 61.

[0069] Next, still referring to FIG. 2, an operation of supplying fuel gas from the fuel gas tank 61 to the fuel cell 51 will be described. When filling the fuel cell 51 with fuel gas, the opening / closing unit B2 of the fuel gas tank 61 opens the outlet flow path of the tank body 611. In addition, the opening / closing unit 633 of the flow rate regulator 63 opens the flow path of the second fuel gas pipe 412. In addition, the flow rate regulator 53 of the fuel cell system 5 opens the flow path of the third fuel gas pipe 413. As a result, the fuel gas is supplied from the fuel gas tank 61 through the second fuel gas pipe 412 and the third fuel gas pipe 413 to the fuel cell 51. Note that, when filling the fuel cell 51 with fuel gas, the opening / closing unit 27 closes the flow path of the inert gas pipe 43, and the opening / closing unit 33 closes the flow path of the pipe 47.

[0070] Next, purging of fuel gas with inert gas will be described with continued reference to FIG. 2. When purging fuel gas with inert gas, the opening / closing unit B2 of the fuel gas tank 61 opens the outlet flow path of the tank body 611, the opening / closing unit 633 of the flow rate regulator 63 opens the flow path of the second fuel gas pipe 412, and the flow rate regulator 53 of the fuel cell system 5 closes the flow path of the third fuel gas pipe 413. The opening / closing unit 33 also opens the flow path of the pipe 47. Then, in a state where fuel gas is not supplied to the fuel gas inlet 21, inert gas is supplied to the inert gas inlet 25. The pressure of the inert gas in this case is, for example, 14.7 MPa.

[0071] Then, when the opening / closing unit 27 opens the flow path of the inert gas pipe 43, the inert gas is supplied from the second backflow regulation unit 31 and the inert gas pipe 43 to the first fuel gas pipe 411, and then through the fuel gas tank 61 to the second fuel gas pipe 412. Furthermore, the inert gas is discharged from the second fuel gas pipe 412 through the pipe 47. As a result, the fuel gas remaining in the first fuel gas pipe 411, the fuel gas remaining in the fuel gas tank 61, and the fuel gas remaining in the second fuel gas pipe 412 are purged with the inert gas.

[0072] The flow rate regulator 53 of the fuel cell system 5 may open the flow path of the third fuel gas pipe 413, and the opening / closing unit 33 may close the flow path of the pipe 47. In this case, when the opening / closing unit 27 opens the flow path of the inert gas pipe 43, the inert gas is supplied from the second backflow regulator 31 and the inert gas pipe 43 to the first fuel gas pipe 411, and then passed through the fuel gas tank 61 to the second fuel gas pipe 412. Furthermore, the inert gas is supplied from the second fuel gas pipe 412 to the fuel cell 51 through the third fuel gas pipe 413 and then discharged. As a result, the fuel gas remaining in the fuel gas pipe 41, the fuel gas remaining in the fuel gas tank 61, and the fuel gas remaining in the fuel cell 51 are purged with the inert gas.

[0073] Next, still referring to FIG. 2, the possibility that the inert gas remaining in the inert gas piping 431 may mix with the fuel gas in the fuel gas piping 41 and control in the event that the inert gas mixes with the fuel gas will be described.

[0074] The internal pressure of the fuel gas tank 61 decreases due to consumption of the fuel gas for power generation by the fuel cell 51. In this case, for example, when the internal pressure of the fuel gas tank 61 becomes equal to or lower than the internal pressure P2 of the first fuel gas pipe 411, the backflow regulating unit B1 opens, allowing gas to flow from the first fuel gas pipe 411 to the tank body 611.

[0075] Furthermore, when the internal pressure P2 of the first fuel gas pipe 411 decreases and becomes equal to or lower than the internal pressure P1 of the inert gas pipe 431, the second backflow control unit 31 opens, and the inert gas remaining in the inert gas pipe 431 may flow into the first fuel gas pipe 411. In this case, the inert gas is mixed into the fuel gas in the first fuel gas pipe 411, and the concentration of the fuel gas decreases.

[0076] Therefore, there is a possibility that the fuel gas whose concentration has been reduced by the inert gas will flow from the first fuel gas pipe 411 into the fuel gas tank 61. As a result, the fuel gas whose concentration has been reduced will be supplied from the fuel gas tank 61 to the fuel cell 51, and the power generation performance of the fuel cell 51 may be reduced.

[0077] Therefore, in the first embodiment, the detection unit 29 detects that the inert gas has passed from the inert gas pipe 431 through the second backflow regulation unit 31 and mixed into the fuel gas in the fuel gas pipe 41.

[0078] Specifically, the detection unit 29 detects a physical quantity (hereinafter, referred to as "physical quantity PY"). The physical quantity PY is a physical quantity capable of indicating that the inert gas has passed from the inert gas pipe 431 through the second backflow regulating unit 31 and mixed into the fuel gas in the fuel gas pipe 41. The mixing of the inert gas into the fuel gas indicates a decrease in the fuel concentration of the fuel gas in the fuel gas pipe 41. Therefore, the physical quantity PY is a physical quantity capable of indicating a decrease in the fuel concentration of the fuel gas in the fuel gas pipe 41. The fuel concentration is typically a hydrogen concentration.

[0079] Specifically, the physical quantity PY is a physical quantity that can indicate that the inert gas has passed from the inert gas pipe 431 through the second backflow regulating unit 31 and mixed into the fuel gas in the first fuel gas pipe 411. The mixing of the inert gas into the fuel gas indicates a decrease in the fuel concentration of the fuel gas in the first fuel gas pipe 411. Therefore, the physical quantity PY is a physical quantity that can indicate a decrease in the fuel concentration of the fuel gas in the first fuel gas pipe 411.

[0080] The physical quantity PY is "pressure" in the first embodiment. The physical quantity PY will be described in detail later.

[0081] The control unit 171 controls at least one of the flow rate adjuster 63 and the flow rate adjuster 53 to adjust the flow rate of the fuel gas based on the detection result of the detection unit 29. Therefore, according to the first embodiment, the control unit 171 can adjust the flow rate of the fuel gas supplied to the fuel cell 51 when the fuel concentration of the fuel gas decreases due to the mixing of an inert gas. As a result, the effect of the decrease in fuel concentration caused by the mixing of an inert gas on the power generation of the fuel cell 51 can be reduced.

[0082] In particular, in the first embodiment, when the detection result of the detection unit 29 indicates that an inert gas has been mixed into the fuel gas, the control unit 171 controls at least one of the flow rate adjustment unit 63 (specifically, the opening and closing unit 633) and the flow rate adjustment unit 53 to set the flow rate of the fuel gas to zero. That is, when the detection result of the detection unit 29 indicates that an inert gas has been mixed into the fuel gas, the control unit 171 controls at least one of the flow rate adjustment unit 63 (specifically, the opening and closing unit 633) and the flow rate adjustment unit 53 to stop the supply of the fuel gas to the fuel cell 51. Thus, the supply of the fuel gas to the fuel cell 51 is stopped, and the fuel cell 51 stops generating power. As a result, it is possible to prevent the effect of a decrease in the fuel concentration on the power generation of the fuel cell 51. That is, since the fuel cell 51 is stopped, a decrease in the fuel concentration does not affect the power generation of the fuel cell 51 in the first place.

[0083] For example, by stopping power generation by a fuel cell 51 whose power generation performance has deteriorated, all of the power required for the propulsion device 9 can be supplied from the storage battery system 7, or all of the power required for the propulsion device 9 can be supplied from another fuel cell.

[0084] Specifically, the control unit 171 controls at least one of the flow rate regulator 63 and the flow rate regulator 53 to regulate the flow rate of the fuel gas based on the internal pressure P1 of the inert gas pipe 431 and the internal pressure P2 of the fuel gas pipe 41 (specifically, the first fuel gas pipe 411). The internal pressure P1 and the internal pressure P2 are physical quantities PY, and can indicate that the inert gas has passed from the inert gas pipe 431 through the second backflow regulating unit 31 and mixed into the fuel gas in the fuel gas pipe 41. Therefore, the flow rate of the fuel gas supplied to the fuel cell 51 can be regulated by determining whether the inert gas has mixed into the fuel gas with a simple configuration for detecting the pressures (the internal pressures P1 and P2).

[0085] More specifically, the internal pressure P2 of the fuel gas pipe 41 is the internal pressure of the first fuel gas pipe 411. Then, the control unit 171 determines whether the internal pressure P1 of the inert gas pipe 431 and the internal pressure P2 of the first fuel gas pipe 411 satisfy the forward passing condition of the second backflow regulation unit 31. The forward passing condition is a condition for the inert gas to pass through the second backflow regulation unit 31 from the upstream to the downstream of the second backflow regulation unit 31. In other words, the forward passing condition is a condition for the inert gas to pass through the second backflow regulation unit 31 in the forward direction FW.

[0086] The forward passing condition is that the internal pressure P1 of the inert gas pipe 431 is equal to or higher than the threshold value TH. That is, when the internal pressure P1 of the inert gas pipe 431 is equal to or higher than the threshold value TH (P1≧TH), the inert gas passes through the second backflow regulation unit 31 from the upstream to the downstream of the second backflow regulation unit 31. Therefore, the inert gas flows from the inert gas pipe 431 into the first fuel gas pipe 411. That is, the internal pressure P1 and the internal pressure P2 satisfying the forward passing condition of the second backflow regulation unit 31 indicates that the inert gas has mixed into the fuel gas in the first fuel gas pipe 411.

[0087] The threshold value TH is not a fixed value, but a variable value that depends on the internal pressure P2 of the first fuel gas pipe 411. Specifically, the threshold value TH is a value obtained by subtracting a margin value MV preset in the second backflow regulation unit 31 from the internal pressure P2 of the fuel gas pipe 41 (TH=P2-MV). The margin value MV is a real number equal to or greater than 0. Note that, when the second backflow regulation unit 31 is a check valve, the margin value MV may be a cracking differential pressure of the check valve.

[0088] When it is determined that the internal pressure P1 of the inert gas pipe 431 and the internal pressure P2 of the first fuel gas pipe 411 satisfy the forward passing condition of the second backflow regulating unit 31, the control unit 171 controls at least one of the flow rate regulator 63 (specifically, the opening / closing unit 633) and the flow rate regulator 53 to stop the supply of fuel gas to the fuel cell 51. Thus, the supply of fuel gas to the fuel cell 51 is stopped, and the fuel cell 51 stops generating power.

[0089] According to embodiment 1, by detecting the internal pressure P1 of the inert gas pipe 431 and the internal pressure P2 of the first fuel gas pipe 411, it is possible to accurately detect that the inert gas has flowed through the second backflow regulating section 31 into the first fuel gas pipe 411.

[0090] Next, the fuel gas regulating method according to the first embodiment will be described with reference to Fig. 2 and Fig. 3. Fig. 3 is a flowchart showing the fuel gas regulating method. As shown in Fig. 3, the fuel gas regulating method includes steps S1 to S3.

[0091] 2 and 3, in step S1, the control unit 171 acquires a detection result from the detection unit 29. Specifically, the control unit 171 acquires information indicating the internal pressure P1 of the inert gas pipe 431 from the first pressure detection unit 291, and acquires information indicating the internal pressure P2 of the first fuel gas pipe 411 from the second pressure detection unit 292.

[0092] Next, in step S2, the control unit 171 determines whether or not an inert gas has been mixed into the fuel gas in the first fuel gas pipe 411, based on the detection result of the detection unit 29. Specifically, the control unit 171 determines whether or not the internal pressure P1 of the inert gas pipe 431 and the internal pressure P2 of the first fuel gas pipe 411 satisfy the forward passing condition of the second backflow regulating unit 31.

[0093] If the determination in step S2 is negative (No), the process ends. A negative determination indicates that the fuel gas is not mixed with an inert gas, that is, that the internal pressures P1 and P2 do not satisfy the forward passing condition.

[0094] On the other hand, if the determination in step S2 is affirmative (Yes), the process proceeds to step S3. A positive determination indicates that it has been determined that the fuel gas is mixed with an inert gas, that is, that it has been determined that the internal pressures P1 and P2 satisfy the forward passing condition.

[0095] Next, in step S3, the control unit 171 controls at least one of the flow rate adjuster 63 (specifically, the opening / closing unit 633) and the flow rate adjuster 53 to stop the supply of fuel gas to the fuel cell 51. Therefore, at least one of the flow rate adjuster 63 (specifically, the opening / closing unit 633) and the flow rate adjuster 53 stops the supply of fuel gas to the fuel cell 51. As a result, the fuel cell 51 stops generating power. Then, the process ends.

[0096] In the first embodiment, the fuel gas supply system 6 does not have to include the second pressure detection unit 292. In this case, the third pressure detection unit 631 functions as the "second pressure detection unit" of the present invention. When the third pressure detection unit 631 functions as the "second pressure detection unit" of the present invention, the opening / closing unit B2 opens the outlet flow path of the tank main body 611. Therefore, the internal pressure P2 of the first fuel gas pipe 411 and the internal pressure P3 of the second fuel gas pipe 412 are approximately equal to each other.

[0097] Specifically, the control unit 171 controls at least one of the flow rate adjuster 63 and the flow rate adjuster 53 to adjust the flow rate of the fuel gas based on the internal pressure P1 of the inert gas pipe 431 and the internal pressure P3 of the fuel gas pipe 41. The internal pressure P1 and the internal pressure P3 are physical quantities PY, and can indicate that the inert gas has passed from the inert gas pipe 43 through the second backflow regulating unit 31 and mixed into the fuel gas in the fuel gas pipe 41.

[0098] More specifically, the internal pressure P3 of the fuel gas pipe 41 is the internal pressure of the second fuel gas pipe 412. That is, the third pressure detection unit 631 detects the internal pressure P3 of the second fuel gas pipe 412.

[0099] Then, the control unit 171 determines whether the internal pressure P1 of the inert gas pipe 431 and the internal pressure P3 of the second fuel gas pipe 412 satisfy the forward passing condition of the second backflow regulating unit 31 or not.

[0100] The forward passing condition is the same as the forward condition when the internal pressures P1 and P2 are used, that is, the internal pressure P1 of the inert gas pipe 431 is equal to or higher than the threshold value TH. However, the threshold value TH is not a fixed value, but a variable value that depends on the internal pressure P3. Specifically, the threshold value TH is a value obtained by subtracting a margin value MV preset in the second backflow regulating unit 31 from the internal pressure P3 (TH=P3-MV). The margin value MV is a real number equal to or greater than 0.

[0101] When it is determined that the internal pressure P1 of the inert gas pipe 431 and the internal pressure P3 of the second fuel gas pipe 412 satisfy the forward passing condition of the second backflow regulating unit 31, the control unit 171 controls at least one of the flow rate regulator 63 (specifically, the opening / closing unit 633) and the flow rate regulator 53 to stop the supply of fuel gas to the fuel cell 51. Thus, the supply of fuel gas to the fuel cell 51 is stopped, and the fuel cell 51 stops generating power.

[0102] By detecting the internal pressure P1 of the inert gas pipe 431 and the internal pressure P3 of the second fuel gas pipe 412, it is possible to easily detect that the inert gas has flowed through the second backflow regulating section 31 into the first fuel gas pipe 411.

[0103] (Modification) A modified example of the first embodiment will be described with reference to Fig. 2. The modified example mainly differs from the first embodiment in that the flow rate of the fuel gas is increased when an inert gas is mixed into the fuel gas. Below, the differences between the modified example and the first embodiment will be mainly described.

[0104] In a modified example, the fuel gas supply system 6 further includes a flow rate adjuster (hereinafter referred to as "flow rate adjuster FL" in this specification; not shown). The flow rate adjuster FL is capable of adjusting the flow rate of the fuel gas supplied to the fuel cell 51. In other words, the flow rate adjuster FL adjusts the flow rate of the fuel gas supplied from the fuel gas tank 61, and supplies the fuel gas to the fuel cell 51 via the third fuel gas pipe 413. The flow rate adjuster FL is disposed upstream of the fuel cell 51. The flow rate adjuster FL is, for example, a compressor.

[0105] 2 indicates that the inert gas has been mixed into the fuel gas, the control unit 171 controls the flow rate regulator FL to reduce the fuel utilization rate of the fuel cell 51 below the fuel utilization rate before the inert gas was mixed into the fuel gas. The fuel utilization rate is expressed by (flow rate of fuel gas contributing to the power generation reaction of the fuel cell 51) / (flow rate of fuel gas supplied to the fuel cell 51). Therefore, increasing the flow rate of the fuel gas supplied to the fuel cell 51 reduces the fuel utilization rate. In other words, reducing the fuel utilization rate corresponds to increasing the flow rate of the fuel gas supplied to the fuel cell 51.

[0106] That is, when the detection result of the detection unit 29 indicates that the inert gas has been mixed into the fuel gas, the control unit 171 controls the flow rate regulator FL to increase the flow rate of the fuel gas to the fuel cell 51 to be greater than the flow rate of the fuel gas before the inert gas was mixed into the fuel gas. Thus, the flow rate of the fuel gas to the fuel cell 51 increases. As a result, even if the fuel concentration of the fuel gas decreases due to the mixing of the inert gas, it is possible to suppress a decrease in the power generation performance of the fuel cell 51. In other words, it is possible to reduce the impact of the decrease in fuel concentration on the fuel cell 51. Therefore, it is possible to continue stable operation of the fuel cell ship 100.

[0107] Specifically, the control unit 171 determines whether or not the internal pressure P1 of the inert gas pipe 431 and the internal pressure P2 of the first fuel gas pipe 411 satisfy the forward passing condition of the second backflow regulating unit 31. The forward passing condition is the same as the forward passing condition of the first embodiment when the internal pressures P1 and P2 are used.

[0108] When it is determined that the internal pressure P1 of the inert gas pipe 431 and the internal pressure P2 of the first fuel gas pipe 411 satisfy the forward passing condition of the second backflow regulating unit 31, the control unit 171 controls the flow rate regulator FL to increase the flow rate of the fuel gas to the fuel cell 51 compared to the flow rate of the fuel gas when the internal pressures P1, P2 do not satisfy the forward passing condition. This makes it possible to suppress a decrease in the power generation performance of the fuel cell 51.

[0109] Next, a fuel gas regulating method according to a modified example of the first embodiment will be described with reference to Fig. 2 and Fig. 4. Fig. 4 is a flowchart showing the fuel gas regulating method according to the modified example. As shown in Fig. 4, the fuel gas regulating method includes steps S11 to S14.

[0110] Steps S11 and S12 are similar to steps S1 and S2 shown in FIG. 3, respectively, and therefore will not be described.

[0111] If the determination in step S12 is affirmative (Yes), the process proceeds to step S13. A positive determination indicates that it has been determined that the fuel gas is mixed with an inert gas, that is, it has been determined that the internal pressures P1 and P2 satisfy the forward passing condition.

[0112] Next, in step S13, the control unit 171 calculates the reduction rate R_Uf of the fuel utilization rate of the fuel cell 51 based on the flow path volume Vh2 of the first fuel gas piping 411, the volume Vtnk of the fuel gas tank 61, and the flow path volume Vn2 of the inert gas piping 43. Specifically, the control unit 171 calculates the reduction rate R_Uf of the fuel utilization rate by formulas (1), (2), and (3).

[0113] R_Uf=Ch2 / Ch2_NM …(1)

[0114] Ch2=(Vh2+Vtk) / (Vn2+Vh2+Vtk) …(2)

[0115] Ch2_NM=1 …(3)

[0116] In formula (1), Ch2 indicates the fuel concentration (specifically, hydrogen concentration) of the fuel gas in the entire path when the inert gas (specifically, nitrogen) flows from the inert gas pipe 431 to the first fuel gas pipe 411. In other words, Ch2 indicates the fuel concentration (specifically, hydrogen concentration) of the fuel gas in the entire path when the inert gas is mixed into the fuel gas. In this case, the "entire path" refers to the entire inert gas pipe 43, the first fuel gas pipe 411, and the fuel gas tank 61.

[0117] Furthermore, in formula (1), Ch2_NM indicates the fuel concentration (specifically, hydrogen concentration) of the fuel gas in the entire path 411 under normal circumstances. In this case, the "entire path" refers to the entire path from the first fuel gas pipe 411 to the fuel gas tank 61. Furthermore, the "normal circumstances" refers to a time when the inert gas is not mixed into the fuel gas, that is, a time when the internal pressure P1 and the internal pressure P2 do not satisfy the forward passing condition.

[0118] As shown in formula (1), the reduction rate R_Uf of the fuel utilization rate is expressed by the ratio of the fuel concentration Ch2 when an inert gas is mixed to the fuel concentration Ch2_NM in normal operation. In the modified example, as shown in formula (3), the fuel concentration Ch2_NM in normal operation is set to "1", that is, 100%.

[0119] The fuel concentration Ch2 when the inert gas is mixed in is expressed by the formula (2). This is because, when the inert gas starts to flow from the inert gas pipe 431 through the second backflow regulating unit 31 into the first fuel gas pipe 411, the inert gas pipe 431 and the first fuel gas pipe 411 communicate with each other, so that the internal pressure P1 of the inert gas pipe 431 becomes substantially the same as the internal pressure P2 of the first fuel gas pipe 411.

[0120] As an example, when the inner diameter of the inert gas pipe 43 is 5.305 mm, the length of the inert gas pipe 43 is 5 m, the inner diameter of the first fuel gas pipe 411 is 3 mm, the length of the first fuel gas pipe 411 is 5 m, Vn2=0.11 L, Vh2=0.04 L, and Vtk=60 L, from the formula (2), the fuel concentration Ch2 when the inert gas is mixed is "0.998", that is, 99.8%. Therefore, from the formula (1), the reduction rate R_Uf of the fuel utilization rate is "0.998", that is, 99.8%.

[0121] The reduction rate R_Uf indicates the ratio of the target fuel utilization rate to the normal fuel utilization rate. The target fuel utilization rate is the target fuel utilization rate after reduction.

[0122] Next, in step S14, the control unit 171 controls the flow rate adjustment unit FL so as to increase the flow rate of the fuel gas supplied to the fuel cell 51 based on the reduction rate R_Uf calculated in step S13, compared to the flow rate of the fuel gas in normal operation. That is, the control unit 171 controls the flow rate adjustment unit FL so as to achieve a target fuel utilization rate indicated by "normal fuel utilization rate x reduction rate R_Uf". Thus, the flow rate adjustment unit FL increases the flow rate of the fuel gas to the fuel cell 51 so as to achieve the target fuel utilization rate. That is, the fuel utilization rate is reduced by the amount that has decreased from the fuel concentration Ch2_NM in normal operation. As a result, it is possible to suppress a decrease in the power generation performance of the fuel cell 51.

[0123] In addition, in a modified example, the fuel gas supply system 6 does not need to include the second pressure detection unit 292. In this case, the third pressure detection unit 631 functions as the "second pressure detection unit" of the present invention. When the third pressure detection unit 631 functions as the "second pressure detection unit" of the present invention, the opening / closing unit B2 opens the outlet flow path of the tank main body 611. Therefore, the internal pressure P2 of the first fuel gas pipe 411 and the internal pressure P3 of the second fuel gas pipe 412 are approximately equal to each other.

[0124] Specifically, the control unit 171 determines whether or not the internal pressure P1 of the inert gas pipe 43 and the internal pressure P3 of the second fuel gas pipe 412 satisfy the forward passing condition of the second backflow regulating unit 31. The forward passing condition is the same as the forward passing condition of the first embodiment when the internal pressures P1 and P3 are used.

[0125] When it is determined that the internal pressure P1 of the inert gas pipe 43 and the internal pressure P3 of the second fuel gas pipe 412 satisfy the forward passing condition of the second backflow regulating unit 31, the control unit 171 controls the flow rate regulator FL to increase the flow rate of the fuel gas supplied to the fuel cell 51 compared to the flow rate of the fuel gas when the internal pressures P1, P3 do not satisfy the forward passing condition. This makes it possible to suppress a decrease in the power generation performance of the fuel cell 51.

[0126] (Embodiment 2) A fuel cell ship 100 according to a second embodiment of the present invention will be described with reference to Fig. 5. The second embodiment differs from the first embodiment mainly in that an estimated value of the internal pressure P2 of the fuel gas pipe 41 (hereinafter referred to as "estimated value PX") is used for control. The configuration of the fuel cell ship 100 according to the second embodiment is similar to the configuration of the fuel cell ship 100 shown in Fig. 1. Below, the differences between the second embodiment and the first embodiment will be mainly described.

[0127] FIG. 5 is a block diagram showing a fuel cell system 5 and a fuel gas supply system 6A according to the second embodiment. As shown in FIG. 5, the fuel cell ship 100 includes a fuel gas supply system 6A. The fuel gas supply system 6A includes a detection unit 29A. The detection unit 29A detects that the inert gas has passed from the inert gas pipe 431 through the second backflow regulation unit 31 and mixed into the fuel gas in the fuel gas pipe 41. Specifically, the detection unit 29A detects a physical quantity PY. The physical quantity PY is a physical quantity that can indicate that the inert gas has passed from the inert gas pipe 431 through the second backflow regulation unit 31 and mixed into the fuel gas in the fuel gas pipe 41 (specifically, the first fuel gas pipe 411). Then, the control unit 171 controls at least one of the flow rate adjustment unit 63 and the flow rate adjustment unit 53 to adjust the flow rate of the fuel gas based on the detection result of the detection unit 29A. This is the same as in the first embodiment. Therefore, in the second embodiment, similarly to the first embodiment, the effect on the power generation of the fuel cell 51 caused by the decrease in fuel concentration due to the inert gas being mixed in can be reduced.

[0128] Specifically, the detection unit 29A includes a first pressure detection unit 291. However, the detection unit 29A does not include the second pressure detection unit 292 shown in Fig. 2. Therefore, in the second embodiment, the configuration of the fuel gas supply system 6A can be simplified.

[0129] In the second embodiment, the internal pressure P1 of the inert gas pipe 431 detected by the first pressure detection unit 291 is the physical quantity PY.

[0130] Furthermore, the control unit 171 calculates an estimated value PX of the internal pressure P2 of the fuel gas pipe 41 (specifically, the first fuel gas pipe 411) based on the flow path volume of the fuel gas pipe 41 (specifically, the flow path volume of the first fuel gas pipe 411) and the supply amount of fuel gas to the fuel cell 51. Then, the control unit 171 controls at least one of the flow rate regulator 63 and the flow rate regulator 53 to regulate the flow rate of the fuel gas based on the internal pressure P1 of the inert gas pipe 43 and the estimated value PX of the internal pressure P2 of the fuel gas pipe 41. Therefore, the flow rate of the fuel gas supplied to the fuel cell 51 can be regulated by determining whether or not the inert gas has been mixed into the fuel gas with a simple configuration that detects the internal pressure P1.

[0131] More specifically, the control unit 171 determines whether the internal pressure P1 of the inert gas pipe 431 and the estimated value PX of the internal pressure P2 of the first fuel gas pipe 411 satisfy the forward passing condition (P1≧TH) of the second backflow regulating unit 31. The fact that the internal pressure P1 and the estimated value PX of the internal pressure P2 satisfy the forward passing condition indicates that the inert gas is mixed into the fuel gas in the first fuel gas pipe 411. The forward passing condition is the same as the forward passing condition of the first embodiment using the internal pressures P1 and P2. However, in the forward passing condition of the second embodiment, the threshold value TH is a variable value that depends on the estimated value PX of the internal pressure P2 of the first fuel gas pipe 411. Specifically, the threshold value TH is a value obtained by subtracting a margin value MV preset in the second backflow regulating unit 31 from the estimated value PX of the internal pressure P2 of the fuel gas pipe 41 (TH=PX-MV). The margin value MV is a real number equal to or greater than 0. When the second backflow regulation portion 31 is a check valve, the margin value MV may be a cracking differential pressure of the check valve.

[0132] According to embodiment 1, by simply detecting the internal pressure P1 of the inert gas piping 431, it is possible to easily detect that the inert gas has flowed into the first fuel gas piping 411 through the second backflow regulating section 31 by utilizing the estimated value PX of the internal pressure P2 of the first fuel gas piping 411.

[0133] When it is determined that the internal pressure P1 of the inert gas pipe 431 and the estimated value PX of the internal pressure P2 of the first fuel gas pipe 411 satisfy the forward passing condition of the second backflow regulating unit 31, the control unit 171 controls at least one of the flow rate regulator 63 (specifically, the opening / closing unit 633) and the flow rate regulator 53 to stop the supply of fuel gas to the fuel cell 51. Thus, the supply of fuel gas to the fuel cell 51 is stopped, and the fuel cell 51 stops generating power.

[0134] The fuel gas regulating method according to the second embodiment is similar to the fuel gas regulating method shown in Fig. 3. However, in the second embodiment, in step S1, the control unit 171 acquires information indicating the internal pressure P1 of the inert gas pipe 431 from the first pressure detection unit 291. The control unit 171 also calculates an estimated value PX of the internal pressure P2 of the first fuel gas pipe 411. In addition, in step S2, the control unit 171 determines whether the internal pressure P1 of the inert gas pipe 431 and the estimated value PX of the internal pressure P2 of the first fuel gas pipe 411 satisfy the forward passing condition of the second backflow regulating unit 31.

[0135] (Modification) A modified example of the second embodiment will be described with reference to Fig. 5. The modified example mainly differs from the second embodiment in that the flow rate of the fuel gas is increased when an inert gas is mixed into the fuel gas. The following mainly describes the differences between the modified example and the second embodiment.

[0136] 5 indicates that an inert gas has been mixed into the fuel gas, the control unit 171 controls the flow rate regulator FL to increase the flow rate of the fuel gas to the fuel cell 51 to be greater than the flow rate of the fuel gas before the inert gas was mixed into the fuel gas. This is the same as in the second embodiment. Therefore, even if the fuel concentration of the fuel gas is reduced due to the mixing of the inert gas, it is possible to suppress a decrease in the power generation performance of the fuel cell 51.

[0137] Specifically, the control unit 171 determines whether or not the internal pressure P1 of the inert gas pipe 431 and the estimated value PX of the internal pressure P2 of the first fuel gas pipe 411 satisfy the forward passing condition of the second backflow regulating unit 31. The forward passing condition is the same as the forward passing condition of the second embodiment when the internal pressure P1 and the estimated value PX are used.

[0138] When it is determined that the internal pressure P1 of the inert gas pipe 431 and the estimated value PX of the internal pressure P2 of the first fuel gas pipe 411 satisfy the forward passing condition of the second backflow regulating unit 31, the control unit 171 controls the flow rate regulator FL to increase the flow rate of the fuel gas to the fuel cell 51 to be greater than the flow rate of the fuel gas when the internal pressure P1 and the estimated value PX do not satisfy the forward passing condition. This makes it possible to suppress a decrease in the power generation performance of the fuel cell 51.

[0139] The fuel gas regulating method according to the modified example of the second embodiment is similar to the fuel gas regulating method shown in Fig. 4. However, in the modified example of the second embodiment, in step S11, the control unit 171 acquires information indicating the internal pressure P1 of the inert gas pipe 431 from the first pressure detection unit 291. The control unit 171 also calculates an estimated value PX of the internal pressure P2 of the first fuel gas pipe 411. In addition, in step S12, the control unit 171 determines whether the internal pressure P1 of the inert gas pipe 431 and the estimated value PX of the internal pressure P2 of the first fuel gas pipe 411 satisfy the forward passing condition of the second backflow regulating unit 31.

[0140] (Embodiment 3) A fuel cell ship 100 according to a third embodiment of the present invention will be described with reference to Fig. 6. The third embodiment differs from the first embodiment mainly in that the amount of electricity resulting from the power generated by the fuel cell 51 (hereinafter referred to as "amount of electricity EA") is used for control. The configuration of the fuel cell ship 100 according to the third embodiment is similar to the configuration of the fuel cell ship 100 shown in Fig. 1. Below, the differences between the third embodiment and the first embodiment will be mainly described.

[0141] Fig. 6 is a block diagram showing a fuel cell system 5A and a fuel gas supply system 6B according to embodiment 3. As shown in Fig. 6, a fuel cell ship 100 includes a fuel cell system 5A and a fuel gas supply system 6B.

[0142] The fuel gas supply system 6B does not have the detection unit 29 shown in Fig. 2. Therefore, according to the third embodiment, the configuration of the fuel gas supply system 6B can be simplified.

[0143] The fuel cell system 5A includes a detection unit 29B. The detection unit 29B detects that the inert gas has passed from the inert gas pipe 431 through the second backflow regulation unit 31 and mixed into the fuel gas in the fuel gas pipe 41. Specifically, the detection unit 29B detects the amount of electricity EA resulting from the power generated by the fuel cell 51.

[0144] The quantity of electricity EA is a physical quantity PY that can indicate that an inert gas has been mixed into the fuel gas. In other words, the quantity of electricity EA is a physical quantity PY that can indicate that the fuel concentration of the fuel gas in the fuel gas piping 41 has decreased. This is because, when the fuel concentration decreases, the power generation performance of the fuel cell 51 decreases, and therefore, the quantity of electricity EA resulting from the power generated by the fuel cell 51 also changes in response to the decrease in the power generation performance.

[0145] The amount of electricity EA is a "voltage" or a "current" in the first embodiment. The amount of electricity EA will be described in detail later.

[0146] The control unit 171 controls at least one of the flow rate adjuster 63 and the flow rate adjuster 53 to adjust the flow rate of the fuel gas based on the amount of electricity EA resulting from the power of the fuel cell 51. Therefore, according to the third embodiment, the control unit 171 can adjust the flow rate of the fuel gas supplied to the fuel cell 51 when the fuel concentration of the fuel gas decreases due to the mixing of an inert gas. As a result, the effect of the decrease in fuel concentration due to the mixing of an inert gas on the power generation of the fuel cell 51 can be reduced. This is the same as in the first embodiment.

[0147] In particular, in embodiment 3, when the detection result of the detection unit 29B indicates that an inert gas has been mixed into the fuel gas, the control unit 171 controls at least one of the flow rate adjustment unit 63 (specifically, the opening / closing unit 633) and the flow rate adjustment unit 53 so as to stop the supply of fuel gas to the fuel cell 51.

[0148] Specifically, detection unit 29B includes an ammeter 290 and a voltmeter 293. Ammeter 290 detects the output current of fuel cell 51, and outputs a signal indicating the current value of the output current to control unit 171. Voltmeter 293 detects the output voltage of fuel cell 51, and outputs a signal indicating the voltage value of the output voltage to control unit 171.

[0149] Each of the output current and output voltage of the fuel cell 51 is an example of an amount of electricity EA resulting from the power generated by the fuel cell 51. When the fuel concentration decreases, the output voltage of the fuel cell 51 decreases. Therefore, when the power output by the fuel cell 51 is controlled to be constant, if the fuel concentration decreases and the output voltage of the fuel cell 51 decreases, the output current is increased. In other words, when the power output by the fuel cell 51 is controlled to be constant, if the fuel concentration decreases, the output current of the fuel cell 51 increases. Note that power is expressed as the product of voltage and current (power = voltage x current).

[0150] Therefore, the control unit 171 determines whether or not the current value of the output current of the fuel cell 51 is equal to or greater than the current threshold value THA. When the current value of the output current of the fuel cell 51 is equal to or greater than the current threshold value THA, this indicates that an inert gas has mixed into the fuel gas in the first fuel gas pipe 411. The current threshold value THA is determined experimentally and / or empirically.

[0151] When it is determined that the current value of the output current of the fuel cell 51 is equal to or greater than the current threshold value THA, the control unit 171 controls at least one of the flow rate regulator 63 (specifically, the opening / closing unit 633) and the flow rate regulator 53 to stop the supply of fuel gas to the fuel cell 51. Thus, the supply of fuel gas to the fuel cell 51 is stopped, and the fuel cell 51 stops generating power.

[0152] Alternatively, the control unit 171 determines whether or not the voltage value of the output voltage of the fuel cell 51 is equal to or less than the voltage threshold value THB. When the voltage value of the output voltage of the fuel cell 51 is equal to or less than the voltage threshold value THB, this indicates that an inert gas has been mixed into the fuel gas in the first fuel gas pipe 411. The voltage threshold value THB is determined experimentally and / or empirically.

[0153] When it is determined that the voltage value of the output voltage of the fuel cell 51 is equal to or less than the voltage threshold value THB, the control unit 171 controls at least one of the flow rate regulator 63 (specifically, the opening / closing unit 633) and the flow rate regulator 53 to stop the supply of fuel gas to the fuel cell 51. Thus, the supply of fuel gas to the fuel cell 51 is stopped, and the fuel cell 51 stops generating power.

[0154] It is sufficient that the fuel cell system 5 A includes at least one of the ammeter 290 and the voltmeter 293 .

[0155] The fuel gas regulation method according to the third embodiment is similar to the fuel gas regulation method shown in Fig. 3. However, in the third embodiment, in step S1, the control unit 171 acquires the current value of the output current of the fuel cell 51 from the ammeter 290. Alternatively, the control unit 171 acquires the voltage value of the output voltage of the fuel cell 51 from the voltmeter 293. Furthermore, in step S2, the control unit 171 determines whether the current value of the output current of the fuel cell 51 is equal to or greater than the current threshold value THA. Alternatively, the control unit 171 determines whether the voltage value of the output voltage of the fuel cell 51 is equal to or less than the voltage threshold value THB.

[0156] (Modification) A modified example of the third embodiment will be described with reference to Fig. 6. The modified example mainly differs from the third embodiment in that the flow rate of the fuel gas is increased when an inert gas is mixed into the fuel gas. Below, the differences between the modified example and the third embodiment will be mainly described.

[0157] 6 is determined to be equal to or greater than the current threshold value THA, the control unit 171 controls the flow rate regulator FL to increase the flow rate of the fuel gas supplied to the fuel cell 51 to be greater than the flow rate of the fuel gas before the inert gas is mixed into the fuel gas. Therefore, even if the fuel concentration of the fuel gas decreases due to the mixing of the inert gas, it is possible to prevent the power generation performance of the fuel cell 51 from decreasing.

[0158] Alternatively, when the control unit 171 determines that the voltage value of the output voltage of the fuel cell 51 is equal to or lower than the voltage threshold value THB, the control unit 171 controls the flow rate regulator FL to increase the flow rate of the fuel gas supplied to the fuel cell 51 to be greater than the flow rate of the fuel gas before the inert gas is mixed into the fuel gas. Therefore, even if the fuel concentration of the fuel gas is reduced due to the mixing of the inert gas, it is possible to suppress a decrease in the power generation performance of the fuel cell 51.

[0159] It is sufficient that the fuel cell system 5 A includes at least one of the ammeter 290 and the voltmeter 293 .

[0160] The fuel gas regulation method according to the modification of the third embodiment is similar to the fuel gas regulation method shown in Fig. 4. However, in the modification of the third embodiment, in step S11, the control unit 171 acquires the current value of the output current of the fuel cell 51 from the ammeter 290. Alternatively, the control unit 171 acquires the voltage value of the output voltage of the fuel cell 51 from the voltmeter 293. Furthermore, in step S12, the control unit 171 determines whether the current value of the output current of the fuel cell 51 is equal to or greater than the current threshold value THA. Alternatively, the control unit 171 determines whether the voltage value of the output voltage of the fuel cell 51 is equal to or less than the voltage threshold value THB.

[0161] (Embodiment 4) A fuel cell ship 100 according to a fourth embodiment of the present invention will be described with reference to Fig. 7. The fourth embodiment differs from the first embodiment mainly in that the fuel concentration of the fuel gas in the fuel gas piping 41 is detected. The configuration of the fuel cell ship 100 according to the first embodiment is similar to the configuration of the fuel cell ship 100 shown in Fig. 1. Below, the differences between the fourth embodiment and the first embodiment will be mainly described.

[0162] 7 is a block diagram showing a fuel cell system 5 and a fuel gas supply system 6C according to embodiment 4. As shown in FIG 6, the fuel cell ship 100 is equipped with a fuel gas supply system 6C. The fuel gas supply system 6C includes a detection unit 29C. Therefore, the fuel gas supply system 6C does not include the detection unit 29 shown in FIG 2.

[0163] The detection unit 29C detects that the inert gas has mixed into the fuel gas in the fuel gas pipe 41 from the inert gas pipe 431 through the second backflow regulation unit 31. Specifically, the detection unit 29C detects the fuel concentration of the fuel gas in the fuel gas pipe 41, and outputs a signal indicating the fuel concentration to the control unit 171. More specifically, the detection unit 29C detects the fuel concentration of the fuel gas in the first fuel gas pipe 411, and outputs a signal indicating the fuel concentration to the control unit 171. The detection unit 29C is typically a concentration sensor.

[0164] The fuel concentration in the fuel gas pipe 41 (the fuel concentration in the first fuel gas pipe 411) is a physical quantity PY that can indicate that an inert gas has been mixed into the fuel gas.

[0165] The control unit 171 controls at least one of the flow rate adjuster 63 and the flow rate adjuster 53 to adjust the flow rate of the fuel gas based on the fuel concentration detected by the detection unit 29C. Therefore, according to the fourth embodiment, the control unit 171 can adjust the flow rate of the fuel gas supplied to the fuel cell 51 when the fuel concentration of the fuel gas decreases due to the mixing of an inert gas. As a result, the effect of the decrease in fuel concentration caused by the mixing of an inert gas on the power generation of the fuel cell 51 can be reduced. This is the same as in the first embodiment.

[0166] In particular, in the fourth embodiment, it is determined whether or not the fuel concentration detected by the detection unit 29C is equal to or lower than the concentration threshold value THC. The concentration threshold value THC is determined experimentally and / or empirically.

[0167] Then, when it is determined that the fuel concentration of the fuel gas is equal to or lower than the concentration threshold value THC, the control unit 171 controls at least one of the flow rate regulator 63 (specifically, the opening / closing unit 633) and the flow rate regulator 53 to stop the supply of the fuel gas to the fuel cell 51. Thus, the supply of the fuel gas to the fuel cell 51 is stopped, and the fuel cell 51 stops generating power. The fact that the fuel concentration of the fuel gas is determined to be equal to or lower than the concentration threshold value THC indicates that an inert gas has been mixed into the fuel gas.

[0168] The fuel gas regulation method according to the fourth embodiment is similar to the fuel gas regulation method shown in Fig. 3. However, in the fourth embodiment, in step S1, the control unit 171 acquires the fuel concentration of the fuel gas from the detection unit 29C. In addition, in step S2, the control unit 171 determines whether the fuel concentration detected by the detection unit 29C is equal to or lower than the concentration threshold value THC.

[0169] Here, the detection unit 29C may detect the concentration of the inert gas in the fuel gas piping 41, and output a signal indicating the concentration of the inert gas to the control unit 171. Specifically, the detection unit 29C may detect the concentration of the inert gas in the first fuel gas piping 411, and output a signal indicating the concentration of the inert gas to the control unit 171. The detection unit 29C is typically a concentration sensor.

[0170] The concentration of the inert gas in the fuel gas pipe 41 (the concentration of the inert gas in the first fuel gas pipe 411) is a physical quantity PY that can indicate that the inert gas has been mixed into the fuel gas.

[0171] The control unit 171 determines whether or not the concentration of the inert gas detected by the detection unit 29C is equal to or greater than a concentration threshold value THD. The concentration threshold value THD is determined experimentally and / or empirically.

[0172] Then, when it is determined that the concentration of the inert gas is equal to or higher than the concentration threshold value THD, the control unit 171 controls at least one of the flow rate regulator 63 (specifically, the opening / closing unit 633) and the flow rate regulator 53 to stop the supply of fuel gas to the fuel cell 51. Thus, the supply of fuel gas to the fuel cell 51 is stopped, and the fuel cell 51 stops generating power.

[0173] (Modification) A modified example of the fourth embodiment will be described with reference to Fig. 7. The modified example mainly differs from the fourth embodiment in that the flow rate of the fuel gas is increased when an inert gas is mixed into the fuel gas. The following mainly describes the differences between the modified example and the fourth embodiment.

[0174] 7 is determined to be equal to or lower than the concentration threshold value THC, the control unit 171 controls the flow rate regulator FL to increase the flow rate of the fuel gas supplied to the fuel cell 51 to be greater than the flow rate of the fuel gas before it was determined that the fuel concentration was equal to or lower than the concentration threshold value THC. Therefore, even if the fuel concentration of the fuel gas is reduced due to the mixing of an inert gas, the power generation performance of the fuel cell 51 can be prevented from being reduced.

[0175] The fuel gas regulation method according to the modification of the fourth embodiment is similar to the fuel gas regulation method shown in Fig. 4. However, in the modification of the fourth embodiment, in step S11, the control unit 171 acquires the fuel concentration from the detection unit 29C. In addition, in step S12, the control unit 171 determines whether the fuel concentration is equal to or lower than the concentration threshold value THC.

[0176] Here, the detection unit 29C may detect the concentration of the inert gas in the fuel gas pipe 41 (the concentration of the inert gas in the first fuel gas pipe 411) and output a signal indicating the concentration of the inert gas to the control unit 171. Then, when it is determined that the concentration of the inert gas is equal to or higher than the concentration threshold value THD, the control unit 171 may control the flow rate regulator FL to increase the flow rate of the fuel gas supplied to the fuel cell 51.

[0177] (Embodiment 5) A fuel cell ship 100 according to a fifth embodiment of the present invention will be described with reference to Fig. 8. The fifth embodiment differs from the first embodiment mainly in that it is provided with a plurality of fuel gas tanks 61. The configuration of the fuel cell ship 100 according to the fifth embodiment is similar to the configuration of the fuel cell ship 100 shown in Fig. 1. Below, the differences between the fifth embodiment and the first embodiment will be mainly described.

[0178] Fig. 8 is a block diagram showing a fuel cell system 5 and a fuel gas supply system 6D according to embodiment 5. As shown in Fig. 8, the fuel gas supply system 6D includes a plurality of fuel gas tanks 61. In the example of Fig. 8, the fuel gas supply system 6D includes fuel gas tanks 61A to 61D. The first fuel gas piping 411 includes a piping 411a and a piping 411b. The second fuel gas piping 412 includes a piping 412a and a piping 412b. In addition, the fuel cell ship 100 includes joints JT1 to JT4.

[0179] The pipe 411a extends from the fuel gas inlet 21 and is connected to the fuel gas tank 61A and the fuel gas tank 61B. Specifically, the pipe 411a is connected to the backflow regulation units B1 of the fuel gas tank 61A and the fuel gas tank 61B. The pipe 411b is connected to the pipe 411a via a joint JT3 and is connected to the fuel gas tank 61C and the fuel gas tank 61D. Specifically, the pipe 411b is connected to the backflow regulation units B1 of the fuel gas tank 61C and the fuel gas tank 61D.

[0180] The pipe 412a is connected to the fuel gas tank 61A and the fuel gas tank 61B, and extends to a joint JT2. Specifically, the pipe 412a is connected to the opening / closing portion B2 of the fuel gas tank 61A and the fuel gas tank 61B. The pipe 412b extends from the fuel gas tank 61C and the fuel gas tank 61D, and is connected to the pipe 412a via a joint JT4. Specifically, the pipe 412b is connected to the opening / closing portion B2 of the fuel gas tank 61C and the fuel gas tank 61D.

[0181] In the fifth embodiment, similarly to the first embodiment, the control unit 171 controls at least one of the flow rate adjuster 63 and the flow rate adjuster 53 to adjust the flow rate of the fuel gas based on the detection result of the detection unit 29. Therefore, according to the fifth embodiment, similarly to the first embodiment, the control unit 171 can adjust the flow rate of the fuel gas supplied to the fuel cell 51 when the fuel concentration of the fuel gas decreases due to the mixing of an inert gas. As a result, the effect of the decrease in fuel concentration caused by the mixing of an inert gas on the power generation of the fuel cell 51 can be reduced.

[0182] In addition, in embodiment 5, the procedure for filling the fuel gas tank 61 with fuel gas, the procedure for purging the fuel gas with an inert gas, and the procedure for supplying the fuel gas to the fuel cell 51 are similar to the procedure for filling the fuel gas tank 61 with fuel gas, the procedure for purging the fuel gas with an inert gas, and the procedure for supplying the fuel gas to the fuel cell 51 in embodiment 1, respectively.

[0183] In addition, the fuel gas supply system 6 according to the modified example of embodiment 1, the fuel gas supply system 6A according to embodiment 2 and its modified examples, the fuel gas supply system 6B according to embodiment 3 and its modified examples, and the fuel gas supply system 6C according to embodiment 4 and its modified examples may be provided with multiple fuel gas tanks 61.

[0184] The embodiments and examples of the present invention have been described above with reference to the drawings. However, the present invention is not limited to the above embodiments, and can be implemented in various aspects without departing from the gist of the present invention. For example, the following modifications (1) to (7) are possible. In addition, the multiple components disclosed in the above embodiments can be modified as appropriate. For example, a certain component among all the components shown in one embodiment may be added to the components of another embodiment, or some of all the components shown in one embodiment may be deleted from the embodiment.

[0185] In addition, the drawings are mainly schematic illustrations of each component to facilitate understanding of the invention, and the thickness, length, number, spacing, etc. of each component shown in the drawings may differ from the actual ones due to the convenience of creating the drawings. In addition, the configurations of each component shown in the above embodiment are merely examples and are not particularly limited, and it goes without saying that various modifications are possible within a range that does not substantially deviate from the effects of the present invention.

[0186] <Notes on the invention> According to one aspect of the present invention, a fuel cell ship includes a propulsion device, a fuel cell, a fuel gas pipe, an inert gas pipe, a backflow regulation unit, a flow rate adjustment unit, a detection unit, and a control unit. The propulsion device generates a propulsive force for a ship body. The fuel cell supplies electric power to the propulsion device. A fuel gas to be supplied to the fuel cell flows through the fuel gas pipe. The inert gas pipe is connected to the fuel gas pipe, and the inert gas is introduced when the fuel gas is purged with the inert gas. The backflow regulation unit is disposed in the inert gas pipe and regulates backflow of the inert gas and the fuel gas. The flow rate adjustment unit is capable of adjusting the flow rate of the fuel gas to be supplied to the fuel cell. The detection unit detects that the inert gas has passed through the backflow regulation unit from the inert gas pipe and mixed into the fuel gas in the fuel gas pipe. The control unit controls the flow rate adjustment unit to adjust the flow rate of the fuel gas based on a detection result of the detection unit. [Industrial Applicability]

[0187] The present invention relates to a fuel cell ship and has industrial applicability. [Explanation of symbols]

[0188] 29, 29A to 29C Detector 31 Second backflow regulation section (backflow regulation section) 41 Fuel gas piping 43 Inert gas piping 51 Fuel Cell 53, 63 Flow rate adjustment section 61, 61A~61D Fuel gas tank 100 fuel cell ship 171 Control Unit 291 First pressure detection unit 292 Second pressure detection unit 411 First fuel gas pipe 412 Second fuel gas piping

Claims

1. A fuel cell that supplies power to a propulsion device that generates a thrust force on the hull or to an auxiliary device installed on the ship; a fuel gas pipe through which a fuel gas supplied to the fuel cell flows; an inert gas pipe connected to the fuel gas pipe and into which the inert gas is introduced when the fuel gas is purged with the inert gas; a backflow prevention unit disposed in the inert gas pipe and configured to prevent backflow of the inert gas and the fuel gas; a flow rate adjusting unit capable of adjusting a flow rate of the fuel gas supplied to the fuel cell; a detection unit that detects that the inert gas has passed from the inert gas piping through the backflow prevention unit and mixed into the fuel gas in the fuel gas piping; a control unit that controls the flow rate adjusting unit to adjust the flow rate of the fuel gas based on a detection result of the detection unit; Equipped with A fuel cell system, wherein when the fuel gas is being supplied to the fuel gas piping, if the detection result of the detection unit indicates that the inert gas has been mixed into the fuel gas, the control unit controls the flow rate adjustment unit so as to reduce the fuel utilization rate of the fuel cell.

2. 2. The fuel cell system of claim 1, wherein when the fuel gas is being supplied to the fuel gas piping and the detection result of the detection unit indicates that the inert gas has been mixed into the fuel gas, the control unit controls the flow rate adjustment unit so that the fuel utilization rate is reduced compared to before the inert gas was mixed into the fuel gas.

3. When the fuel gas is supplied to the fuel gas piping, if the detection result of the detection unit indicates that the inert gas has been mixed into the fuel gas, The control unit is 3. The fuel cell system according to claim 1, further comprising: a flow rate adjustment unit that adjusts a flow rate of the fuel cell to a flow rate of the inert gas piping; a flow rate adjustment unit that adjusts a flow rate of the fuel cell to a flow rate of the inert gas piping; and a flow rate adjustment unit that adjusts a flow rate of the fuel cell to a flow rate of the inert gas piping.

4. A fuel cell system according to any one of claims 1 to 3; The hull; The propulsion device; The auxiliary machine and A fuel cell ship equipped with:

Images