Power generation system

Abstract

The present invention provides a power generation system that can mitigate the problems that arise when fuel gas leaking from a fuel cell enters the cooling medium tank and is released from the gas outlet of the gas discharge piping inside the cooling tank. [Solution] The power generation system is a power generation system equipped with a fuel cell that generates electricity by the electrochemical reaction of fuel, and comprises a cooling system for cooling the fuel cell and an oxidizer gas piping. The cooling system has a cooling medium tank that contains a cooling medium and a cooling tank internal gas discharge piping connected to the cooling medium tank. The gas discharge port of the cooling tank internal gas discharge piping is located above the inlet of the oxidizer gas piping.

Description

Technical Field

[0001] The present invention relates to a power generation system.

Background Art

[0002] Conventionally, a fuel cell ship has been proposed in which fuel gas (for example, hydrogen gas) is supplied from a fuel tank to a fuel cell, and a propulsion device is driven by the electric power generated by the fuel cell (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A fuel cell generates heat while generating electricity. In order to maintain appropriate power generation efficiency of the fuel cell, it is desirable to cool the fuel cell, for example, by supplying a cooling medium (for example, cooling water). However, in such a configuration, when fuel gas leakage occurs in the fuel cell for some reason, the leaked fuel gas may enter the cooling medium tank and be discharged from the gas discharge port of the internal gas discharge pipe of the cooling tank connected to the cooling medium tank. Therefore, some countermeasures are necessary.

[0005] The present invention has been made to solve the above problems, and an object thereof is to provide a power generation system capable of reducing the inconvenience that occurs when fuel gas leaked from a fuel cell enters a cooling medium tank and is discharged from the gas discharge port of an internal gas discharge pipe of a cooling tank.

Means for Solving the Problems

[0006] A power generation system according to one aspect of the present invention is a power generation system comprising a fuel cell that generates electricity by an electrochemical reaction of fuel, comprising a cooling system for cooling the fuel cell and an oxidizer gas piping, wherein the cooling system comprises a cooling medium tank for containing a cooling medium and a cooling tank internal gas discharge piping connected to the cooling medium tank, and the gas discharge port of the cooling tank internal gas discharge piping is located above the inlet of the oxidizer gas piping. [Effects of the Invention]

[0007] The above configuration makes it possible to reduce the problems that occur when fuel gas leaking from the fuel cell enters the cooling medium tank and is released from the gas outlet of the gas discharge piping inside the cooling tank. [Brief explanation of the drawing]

[0008] [Figure 1] This is an explanatory diagram showing the schematic configuration of a fuel cell ship according to one embodiment of the present invention. [Figure 2] This is a schematic diagram illustrating the internal structure of the fuel cell ship described above. [Figure 3] This is a schematic diagram illustrating the general configuration of the fuel cell system installed in the fuel cell ship described above. [Figure 4] This flowchart shows the processing flow resulting from the opening and closing control of the gas release valve inside the cooling tank of the fuel cell ship described above. [Figure 5] This is a schematic diagram illustrating the main components of the fuel cell ship described above. [Figure 6] This is a schematic diagram illustrating the other components of the main parts of the fuel cell ship described above. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below with reference to the drawings. In this specification, directions are defined as follows. First, the direction from the stern to the bow of the fuel cell vessel is defined as "forward," and the direction from the bow to the stern is defined as "rear." The lateral direction perpendicular to the longitudinal direction is defined as the left-right direction. In this case, when the fuel cell vessel is moving forward, the left side as seen from the perspective of the operator is defined as "left," and the right side is defined as "right." Furthermore, the upstream side in the direction of gravity perpendicular to the longitudinal and left-right directions is defined as "up," and the downstream side is defined as "down."

[0010] [1. Outline of the fuel cell ship's configuration] First, the fuel cell vessel SH according to this embodiment will be described with reference to Figure 1. Figure 1 is an explanatory diagram showing the schematic configuration of the fuel cell vessel SH. The fuel cell vessel SH comprises a hull 1 and a cabin 2. The cabin 2 is located on the upper surface of the hull 1.

[0011] The fuel cell ship SH further comprises a fuel cell system 3, a fuel gas storage unit 4, a battery system 5, a propulsion system 6, a cooling system 7, a plurality of peripheral devices 11, and a control device 12. In Figure 1, control signals or high-voltage power supply lines are shown as solid lines, and control signals or low-voltage power supply lines are shown as dashed lines.

[0012] The fuel cell system 3 functions as the main power source. The fuel cell system 3 generates electricity (specifically, DC electricity) by consuming fuel gas. Fuel gas is an example of a fuel, such as a combustible gas. Typically, the fuel gas is hydrogen gas. The fuel cell system 3 supplies the generated electricity to the propulsion system 6 and peripheral equipment 11. The fuel cell system 3 can also supply power to the battery system 5 to charge it. Further details of the fuel cell system 3 will be described later.

[0013] The fuel gas storage unit 4 stores fuel gas to be supplied to the fuel cell system 3. Specifically, the fuel gas storage unit 4 has a fuel tank 41 (see Figure 2) that contains fuel gas as fuel. The fuel gas is supplied from the fuel tank 41 to the fuel cell system 3 via a fuel gas supply pipe 32 (see Figure 2), which will be described later.

[0014] The battery system 5 has a battery. The battery is, for example, a lithium secondary battery, but may also be a nickel-cadmium battery, a nickel-metal hydride battery, etc. The battery system 5 functions as an auxiliary power source that supplies stored power (specifically DC power) to the propulsion device 6 and peripheral equipment 11. In this way, the battery system 5 functions as an auxiliary power source, which can compensate for any shortage of power supplied from the fuel cell system 3 to the propulsion device 6, etc. The battery system 5 may also supply power to the control device 12.

[0015] The propulsion system 6 is driven by electricity supplied from the fuel cell 31 (see Figure 2), which will be described later, of the fuel cell system 3, and generates thrust in the hull 1. In other words, the fuel cell ship SH is equipped with a propulsion system 6 that generates thrust in the hull 1 using electricity supplied from the fuel cell 31.

[0016] The propulsion system 6 may be driven solely by power supplied from the battery of the battery system 5, or it may be driven by power supplied from both the fuel cell 31 and the battery. In other words, the propulsion system 6 may be driven by power supplied from at least one of the fuel cell and the battery to generate thrust in the hull 1.

[0017] The propulsion device 6 includes a power conversion device 6a, a propulsion motor 6b, and a propeller 6c. The power conversion device 6a converts the power supplied from the fuel cell system 3 into power corresponding to the specifications of the propulsion motor 6b. For example, the power conversion device 6a converts DC power into AC power. In this case, the power conversion device 6a has, for example, an inverter. The propulsion motor 6b is driven by the power (for example, AC power) supplied from the power conversion device 6a. When the propulsion motor 6b is driven, the rotational force of the propulsion motor 6b is transmitted to the propeller 6c. As a result, the propeller 6c rotates and a propulsion force is generated on the hull 1. Note that a configuration having a marine gear between the propulsion motor 6b and the propeller 6c may also be adopted.

[0018] The peripheral devices 11 include, for example, a compressor, a solenoid valve, a pump, and the like. The peripheral devices 11 also include electrical devices such as lighting devices and air conditioning devices, but the types of the peripheral devices 11 are not particularly limited.

[0019] The control device 12 controls the fuel cell system 3, the fuel gas storage unit 4, the battery system 5, the propulsion device 6, the cooling system 7, and the plurality of peripheral devices 11. The control device 12 is constituted by, for example, one or two or more computers. The computer is, for example, a PLC (Programable Logic Controller), but may also be an ECU (Electronic Control Unit). Power is supplied to the control device 12 from a battery (for example, a lead battery) not shown or from the battery of the battery system 5.

[0020] The control device 12 includes a control unit 12a and a storage unit 12b. The control unit 12a includes a processor such as a CPU (Central Processing Unit). The storage unit 12b includes a storage device and stores data and computer programs. Specifically, the storage unit 12b 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 12b may include a removable medium. The storage unit 12b corresponds to an example of a non-transitory computer-readable storage medium.

[0021] The processor of the control unit 12a controls the fuel cell system 3, the fuel gas storage unit 4, the battery system 5, the propulsion device 6, the cooling system 7, and the plurality of peripheral devices 11 by executing a computer program stored in the storage device of the storage unit 12b.

[0022] The cooling system 7 has a function of cooling the fuel cell system 3, particularly the fuel cell 31. That is, the fuel cell ship SH of the present embodiment includes a cooling system 7 that cools the fuel cell 31. Details of the cooling system 7 will be described later.

[0023] 〔2. Details of the Fuel Cell System〕 Next, details of the fuel cell system 3 will be described. FIG. 2 is an explanatory diagram schematically showing the internal structure of the fuel cell ship SH.

[0024] The fuel cell ship SH includes an engine room 13 and a fuel room 14. The engine room 13 and the fuel room 14 are arranged below the deck 1a of the hull 1. In other words, the engine room 13 and the fuel room 14 are arranged between the deck 1a and the bottom plate 1b of the hull 1. Note that the bottom plate 1b is located between the deck 1a and the bottom of the ship 1c (see FIG. 1).

[0025] The engine room 13 is located towards the bow relative to the fuel room 14. The engine room 13 and the fuel room 14 are separated by a bulkhead (not shown). The bulkhead is made of, for example, fiber-reinforced plastic (FRP), but may also be made of sheet metal. The fuel tank 41 of the fuel gas storage section 4 is located inside the fuel room 14. Thus, the fuel cell ship SH is equipped with a fuel tank 41 for storing fuel.

[0026] The fuel cell system 3 of the fuel cell ship SH is located in the engine room 13. The fuel cell system 3 comprises a fuel cell 31, a fuel gas supply pipe 32, and a fuel cell side shut-off valve 33. The fuel cell side shut-off valve 33 is an example of peripheral equipment 11 (see Figure 1).

[0027] The fuel cell 31 generates electricity (specifically DC electricity) through an electrochemical reaction between a fuel gas, which is an example of a fuel, and an oxidizer gas. Typically, the oxidizer gas is air, and the oxidizer is oxygen. In other words, the fuel cell ship SH is equipped with a fuel cell 31 that generates electricity through an electrochemical reaction of fuel.

[0028] Figure 3 is a schematic diagram illustrating the general configuration of the fuel cell 31. The fuel cell 31 is, for example, a polymer electrolyte fuel cell (PEFC), and is a fuel cell stack composed of multiple cells 310 stacked on top of each other. In Figure 3, the fuel cell 31 is shown simply with two cells 310. Each cell 310 of the fuel cell 31 has a solid polymer electrolyte membrane 311, an anode electrode 312, a cathode electrode 313, and a pair of separators 314a and 314b.

[0029] The anode electrode 312 and the cathode electrode 313 are separated by a solid polymer electrolyte membrane 311. The anode electrode 312 is the negative electrode (fuel electrode). The anode electrode 312 includes an anode catalyst layer and a gas diffusion layer. The cathode electrode 313 is the positive electrode (air electrode). The cathode electrode 313 includes a cathode catalyst layer and a gas diffusion layer. The anode electrode 312, the solid polymer electrolyte membrane 311, and the cathode electrode 313 constitute a membrane electrode assembly (MEA). A pair of separators 314a and 314b sandwich the membrane electrode assembly.

[0030] Each separator 314a and 314b is made of, for example, SUS (stainless steel) and has ribs with an uneven shape that form multiple grooves on both sides. Each groove located on one side of separator 314a (the side facing the anode electrode 312) forms a fuel gas flow path CH1. Each groove located on one side of separator 314b (the side facing the cathode electrode 313) forms an oxidizer gas flow path CH2. In addition, each groove on the other side of separator 314b of any cell 310 (for example, cell 310B) and each groove on the other side of separator 314a of an adjacent cell 310 (for example, cell 310A) form a cooling medium flow path CH3, which will be described later. Various sensors (pressure sensors, temperature sensors, etc.) are provided in flow paths CH1 and CH3, but this will be described later.

[0031] In Figure 3, a cooling medium channel CH3 is provided between adjacent cells 310, but it is not always necessary to have a channel CH3 between each cell 310. As long as each cell 310 can be cooled to an appropriate temperature, it is also possible to have a configuration with a cooling medium channel CH3 every few cells stacked.

[0032] In the above configuration of the fuel cell 31, for example, on the anode electrode 312 side of cell 310B, hydrogen contained in the fuel gas flowing through the channel CH1 is decomposed into hydrogen ions and electrons by the catalyst. The hydrogen ions permeate the solid polymer electrolyte membrane 311 and move to the cathode electrode 313 side. The uneven rib shape of separator 314a of cell 310B is in contact with the anode electrode 312 across the channel CH1, so electrons generated at the anode electrode 312 move to separator 314a. Separator 314b of cell 310B, which is sandwiching separator 314a and the cooling medium channel CH3, is in contact with each other by their ribs, so the above electrons move from separator 314a to separator 314b. The electrons that have moved to separator 314b pass through the external circuit 315 and move to separator 314a at the opposite end in the stacking direction. This generates an electric current (electricity is generated).

[0033] Since the separator 314b of cell 310A, which is sandwiched between separator 314a and the cooling medium flow path CH3, is in contact with each other at their ribs, the electrons described above move from separator 314a to separator 314b of cell 310A. The uneven rib shape of separator 314b is in contact with the cathode electrode 313 across the oxidizer gas flow path CH2, so the electrons that have moved to separator 314b move to the cathode electrode 313. On the cathode electrode 313 side, the oxygen contained in the oxidizer gas flowing through flow path CH2 combines with the electrons described above and hydrogen ions that have passed through the solid polymer electrolyte membrane to produce water. The produced water is discharged overboard via the discharge pipe 31a (see Figure 2).

[0034] The fuel cell 31 supplies the generated electricity to the propulsion system 6 and peripheral equipment 11 shown in Figure 1. Alternatively, the fuel cell 31 may indirectly supply the generated electricity to the propulsion system 6 and peripheral equipment 11 via a circuit such as a DC / DC converter.

[0035] The fuel gas supply pipe 32 shown in Figure 2 is a fuel supply pipe for supplying fuel gas stored in the fuel tank 41 of the fuel gas storage unit 4 to the anode electrode 312 (see Figure 3) of the fuel cell 31. In other words, the fuel cell ship SH is equipped with a fuel gas supply pipe 32 that supplies fuel from the fuel tank 41 to the fuel cell 31.

[0036] The fuel cell side shut-off valve 33 is a shut-off valve that opens or closes the flow path of the fuel gas supply pipe 32. The opening and closing of the fuel cell side shut-off valve 33 is controlled by the control unit 12a (see Figure 1). Specifically, the fuel cell side shut-off valve 33 switches between supplying and stopping the supply of fuel gas from the fuel tank 41 to the fuel cell 31 based on the control of the control unit 12a. In the fuel cell compartment 30, which will be described later, only one fuel cell side shut-off valve 33 is provided in the fuel gas supply pipe 32, but two or more may be provided.

[0037] The fuel cell ship SH is further equipped with a fuel cell compartment 30. The fuel cell compartment 30 is a housing for the fuel cell 31 and is located in the engine room 13.

[0038] The fuel cell compartment 30 has a hollow shape. For example, the fuel cell compartment 30 has a hollow, substantially rectangular parallelepiped shape. In this case, the outer walls constituting the fuel cell compartment 30 include, for example, a top wall 30a, a bottom wall 30b, a front wall (not shown), a rear wall (not shown), a side wall 30c, and a side wall 30d. However, the top, bottom, front, rear, and sides of the fuel cell compartment 30 can be arbitrarily determined. Furthermore, the shape of the fuel cell compartment 30 is not particularly limited as long as it has space to accommodate the fuel cell 31. The fuel cell compartment 30 can also be considered as a container, chamber, or box that houses the fuel cell 31. The material of the outer walls of the fuel cell compartment 30 is, for example, FRP, but it may also be sheet metal.

[0039] A battery compartment air inlet 30e is provided as an opening in the side wall 30d of the fuel cell compartment 30. The battery compartment air inlet 30e is connected to a battery compartment air supply pipe 35. The battery compartment air supply pipe 35 extends from the battery compartment air inlet 30e to the deck 1a and is exposed from the upper surface of the deck 1a. Note that the battery compartment air inlet 30e may also be provided in an outer wall other than the side wall 30d of the fuel cell compartment 30.

[0040] Meanwhile, a battery compartment exhaust port 30f is provided as an opening in the side wall 30c of the fuel cell compartment 30. The battery compartment exhaust port 30f is connected to a communication section 36. The communication section 36 communicates with a duct compartment (not shown) that forms an exhaust passage. The duct compartment also communicates with a vent pipe (not shown) that leads to the outside of the ship. As a result, air that enters the interior of the fuel cell compartment 30 from the battery compartment air supply pipe 35 via the battery compartment air supply port 30e is discharged to the outside of the ship via the battery compartment exhaust port 30f, the communication section 36, the duct compartment, and the vent pipe. Consequently, the interior of the fuel cell compartment 30 is ventilated.

[0041] The fuel cell compartment 30 has a sealed space inside, except for the battery compartment air intake port 30e and the battery compartment exhaust port 30f.

[0042] The fuel cell compartment 30 houses a portion of the aforementioned fuel gas supply piping 32 and a fuel cell side shut-off valve 33. Furthermore, the fuel cell compartment 30 also houses a battery compartment internal gas detector 34a and a battery compartment internal fire detector 34b.

[0043] The internal battery compartment gas detector 34a is a fuel gas detector located inside the fuel cell compartment 30. For example, if the fuel gas is hydrogen gas, the internal battery compartment gas detector 34a consists of a hydrogen gas detection sensor.

[0044] The internal battery compartment gas detector 34a is positioned on the inner surface of the top wall 30a located above the fuel cell compartment 30. Hydrogen gas, used as fuel gas, is lighter than air and rises. Therefore, by positioning the internal battery compartment gas detector 34a on the top wall 30a of the fuel cell compartment 30, even if fuel gas leaks within the fuel cell compartment 30, the leaked fuel gas can be reliably detected by the internal battery compartment gas detector 34a. The installation position of the internal battery compartment gas detector 34a may also be configured to be located at the downstream end of the flow path through which the fuel gas flows when fuel gas leaks within the fuel cell compartment 30.

[0045] When the internal battery compartment gas detector 34a detects fuel gas in the fuel cell compartment 30, the detection signal is sent from the internal battery compartment gas detector 34a to the control unit 12a. This allows the control unit 12a to control the fuel cell side shut-off valve 33 installed in the fuel gas supply pipe 32 to stop the supply of fuel gas from the fuel tank 41 to the fuel cell 31.

[0046] The internal battery compartment fire detector 34b is a fire detector located inside the fuel cell compartment 30. The internal battery compartment fire detector 34b includes, for example, one or more sensors from among a smoke sensor for detecting smoke, a heat sensor for detecting heat, and a flame sensor for detecting flames. The internal battery compartment fire detector 34b may consist of a thermocouple type fire detector.

[0047] The internal battery compartment fire detector 34b is located on the inner surface of the top wall 30a, which is situated above the fuel cell compartment 30. If a fire occurs inside the fuel cell compartment 30, the internal battery compartment fire detector 34b will detect the fire and output a detection signal to the control unit 12a indicating that a fire has occurred. In this case, the control unit 12a can control the fuel cell side shut-off valve 33 to stop the supply of fuel gas from the fuel tank 41 to the fuel cell 31. This minimizes the risk of explosion due to ignition of the fuel gas in the fuel cell compartment 30.

[0048] Further explanation of the fuel cell system 3 described above is provided. The fuel cell system 3 includes an oxidant gas flow rate adjustment unit 321, an off-gas circulation unit 322, a gas-liquid separation unit 323, and a discharge unit 324. The oxidant gas flow rate adjustment unit 321, the off-gas circulation unit 322, and the discharge unit 324 are examples of peripheral equipment 11. The control unit 12a controls the oxidant gas flow rate adjustment unit 321, the off-gas circulation unit 322, and the discharge unit 324. The fuel cell system 3 also includes a discharge pipe 31a, an oxidant gas pipe 31b, an off-gas circulation pipe 31c, and a connecting pipe 31d. Inside the fuel cell 31, a manifold is formed for circulating fuel gas, oxidant gas, and a cooling medium, which will be described later.

[0049] The oxidant gas flow rate adjustment unit 321 supplies oxidant gas to the cathode electrode 313 (see Figure 3) of the fuel cell 31. Specifically, the oxidant gas flow rate adjustment unit 321 adjusts the flow rate of oxidant gas supplied to the fuel cell 31. Typically, the oxidant gas flow rate adjustment unit 321 is an air compressor that compresses the oxidant gas.

[0050] The oxidizer gas piping 31b guides the oxidizer gas supplied from the oxidizer gas flow rate adjustment unit 321 to the cathode electrode 313 of the fuel cell 31.

[0051] The aforementioned exhaust pipe 31a is connected to the exhaust manifold on the cathode electrode 313 side, which is located inside the fuel cell 31. The exhaust pipe 31a guides the oxidizer off-gas and water discharged from the fuel cell 31 to the atmosphere. The oxidizer off-gas represents the exhaust from the cathode electrode 313. In other words, the oxidizer off-gas is the cathode off-gas.

[0052] The gas-liquid separation unit 323 separates water contained in the fuel off-gas discharged from the fuel cell 31 and discharges the water into the connecting pipe 31d. In addition, the gas-liquid separation unit 323 discharges the excess fuel gas, which is the fuel off-gas after the water has been separated, into the off-gas circulation pipe 31c. Typically, the gas-liquid separation unit 323 is a gas-liquid separator. The fuel off-gas represents the exhaust from the anode electrode 312 (see Figure 3) of the fuel cell 31. In other words, the fuel off-gas is the anode off-gas.

[0053] The off-gas circulation unit 322 is located in the off-gas circulation piping 31c. The off-gas circulation unit 322 discharges excess fuel gas discharged from the gas-liquid separation unit 323 to the fuel gas supply piping 32. The fuel gas supply piping 32 then supplies the excess fuel gas to the fuel cell 31. Typically, the off-gas circulation unit 322 is a pump. However, for example, the off-gas circulation unit 322 may also be an ejector.

[0054] The discharge section 324 is located in the connecting pipe 31d. The discharge section 324 discharges the water separated by the gas-liquid separation section 323. In addition, the discharge section 324 discharges a portion of the fuel off-gas discharged from the fuel cell 31, i.e., the remaining gas and water that was not supplied to the off-gas circulation pipe 31c. Typically, the discharge section 324 is a purge valve.

[0055] The water and fuel off-gas discharged from the discharge section 324 are discharged through the connecting pipe 31d to the discharge pipe 31a, and together with the oxidizer off-gas (cathode off-gas) discharged from the fuel cell 31, they are guided from the discharge pipe 31a to the atmosphere.

[0056] [3. Details of the cooling system] Next, the details of the cooling system 7 will be described with reference to Figure 2. The cooling system 7 includes a cooling medium tank 71, a cooling medium circulation pipe 72, a cooling tank internal gas detector 73, a cooling tank internal gas discharge pipe 74, and a cooling tank internal gas discharge valve 75.

[0057] The cooling medium tank 71 is a container for holding the cooling medium. The cooling medium is, for example, an antifreeze with low electrical conductivity. The antifreeze is, for example, a liquid obtained by mixing pure water and ethylene glycol in a predetermined ratio.

[0058] The cooling medium tank 71 is installed inside the engine room 13, outside the fuel cell compartment 30. Since the cooling medium tank 71 is installed in the engine room 13, it can be said that the engine room 13 constitutes a cooling medium installation compartment. Therefore, it can be said that the fuel cell ship SH is equipped with a cooling medium installation compartment (engine room 13) where the cooling medium tank 71 is installed.

[0059] The fuel gas supply pipe 32 described above extends from the fuel chamber 14 to the engine room 13 and connects to the fuel cell 31 in the fuel cell compartment 30. In other words, the fuel gas supply pipe 32 passes through the cooling medium installation compartment.

[0060] Furthermore, the engine room 13, which is the compartment where the cooling medium is installed, has a ventilation opening 13a that communicates with the outside of the ship. The ventilation opening 13a is an intake and exhaust opening formed by penetrating the deck 1a, which is the upper wall of the engine room 13. In this embodiment, the ventilation openings 13a are provided on the starboard and port sides of the hull 1, respectively. When the air compressor (not shown) inside the engine room 13 is not running, for example, outside air is drawn into the engine room 13 from the starboard ventilation opening 13a. The air inside the engine room 13 is then discharged to the outside through the port ventilation opening 13a. Conversely, outside air may be drawn into the engine room 13 from the port ventilation opening 13a and discharged to the outside through the starboard ventilation opening 13a. In either of the above airflows, the inside of the engine room 13 is ventilated. In addition, intake and exhaust may occur only through the starboard ventilation opening 13a, or only through the port ventilation opening 13a. On the other hand, when the air compressor in the engine room 13 is running, the air compressor draws air into the engine room 13 through the starboard and port ventilation openings 13a.

[0061] The cooling medium circulation piping 72 is a pipe for circulating the cooling medium between the fuel cell 31 and the cooling medium tank 71. A cooling medium circulation unit 76 and a heat exchanger 77 are located in the middle of the cooling medium circulation piping 72. The cooling medium circulation unit 76 is composed of, for example, a pump. When the cooling medium circulation unit 76 is driven, the cooling medium flows through the cooling medium circulation piping 72, and the cooling medium circulates between the fuel cell 31 and the cooling medium tank 71. The fuel cell 31 is cooled by the supply of cooling medium. The cooling medium used to cool the fuel cell 31 passes through the cooling medium circulation piping 72, undergoes heat exchange in the heat exchanger 77 and is cooled, and then returned to the cooling medium tank 71. The heat exchanger 77 may be installed in the cooling medium circulation piping 72 between the cooling medium tank 71 and the cooling medium circulation unit 76.

[0062] In Figure 2, the cooling medium circulation unit 76 is located within the fuel cell compartment 30, but it may also be located within the engine room 13, outside the fuel cell compartment 30.

[0063] Thus, the cooling system 7 includes a cooling medium tank 71 for containing a cooling medium, and a cooling medium circulation pipe 72 for circulating the cooling medium between the fuel cell 31 and the cooling medium tank 71.

[0064] The cooling tank internal gas detector 73 is installed in the upper part of the inside of the cooling medium tank 71 and is a fuel gas detector that detects the fuel gas present inside the cooling medium tank 71. For example, if the fuel gas is hydrogen gas, the cooling tank internal gas detector 73 consists of a hydrogen gas detection sensor.

[0065] The fuel gas present in the cooling medium tank 71 may be, for example, fuel gas that leaked from the fuel cell 31 and entered the cooling medium tank 71 via the cooling medium circulation piping 72. The fuel gas detection result (e.g., information on the fuel gas concentration) from the cooling tank internal gas detector 73 is sent to the control unit 12a. Based on the detection result from the cooling tank internal gas detector 73, the control unit 12a can determine whether or not there is a fuel gas leak in the fuel cell 31, and if there is a leak, it can perform control to stop power generation in the fuel cell 31, for example.

[0066] The cooling tank internal gas discharge pipe 74 is connected to the cooling medium tank 71 and is a pipe for discharging fuel gas present inside the cooling medium tank 71 to the outside. The outlet of the cooling tank internal gas discharge pipe 74, that is, the end of the cooling tank internal gas discharge pipe 74 opposite to the side connected to the cooling medium tank 71, constitutes a gas discharge port 74a for discharging fuel gas.

[0067] The gas outlet 74a is located above the electrical equipment EM in the cooling medium installation compartment (engine room 13). Also, the ventilation opening 13a of the engine room 13 is located above the gas outlet 74a. The reason for specifying this positional relationship will be explained later. The electrical equipment EM is equipment that constitutes the peripheral equipment 11. Specific examples of electrical equipment EM include, for example, an air compressor, a junction box that relays the power generated by the fuel cell 31 between it and the power conversion device 6a (see Figure 1), an inverter, and a converter.

[0068] The cooling tank internal gas release valve 75 is installed in the cooling tank internal gas release pipe 74 and opens or closes the flow path of fuel gas through the cooling tank internal gas release pipe 74. The opening and closing of the cooling tank internal gas release valve 75 is controlled by the control unit 12a.

[0069] Thus, the cooling system 7 includes a cooling tank internal gas detector 73 installed in the cooling medium tank 71, a cooling tank internal gas discharge pipe 74 connected to the cooling medium tank 71, and a cooling tank internal gas discharge valve 75 installed in the cooling tank internal gas discharge pipe 74. The fuel cell ship SH is also equipped with a control unit 12a that controls the opening and closing of the cooling tank internal gas discharge valve 75.

[0070] Next, the details of the control of the cooling tank internal gas release valve 75 by the control unit 12a will be explained with reference to Figure 4. Figure 4 is a flowchart showing the processing flow due to the control of the cooling tank internal gas release valve 75.

[0071] When the cooling tank internal gas detector 73 detects that the concentration of fuel gas (e.g., hydrogen gas) in the cooling medium tank 71 is above a standard value (Yes in S1), the control unit 12a opens the cooling tank internal gas release valve 75 (S2). In this case, the fuel gas present in the cooling medium tank 71 is released through the cooling tank internal gas release pipe 74 and out of the gas outlet 74a. Because fuel gas is light, the fuel gas released from the gas outlet 74a rises in the engine room 13 and is discharged overboard through the ventilation opening 13a of the engine room 13.

[0072] For example, 40% LEL could be considered as the standard value mentioned above, but it should be determined appropriately based on experiments or experience.

[0073] On the other hand, if the cooling tank internal gas detector 73 detects that the concentration of fuel gas in the cooling medium tank 71 is below the standard value (No in S1), the control unit 12a closes the cooling tank internal gas release valve 75 (S3). This maintains a sealed state inside the cooling medium tank 71.

[0074] As described above, when the cooling tank internal gas detector 73 detects that the concentration of fuel gas (fuel in gaseous state) in the cooling medium tank 71 is above a predetermined standard value, the control unit 12a opens the cooling tank internal gas release valve 75 (S1, S2). As a result, even if a fuel gas leak occurs in the fuel cell 31 for any reason and the leaked fuel gas enters the cooling medium tank 71 via the cooling medium circulation pipe 72, the fuel gas is released from the cooling tank internal gas release pipe 74 via the cooling tank internal gas release valve 75. Therefore, the situation in which leaked fuel gas accumulates in the cooling medium tank 71 can be reduced.

[0075] Furthermore, as described above, the gas outlet 74a of the cooling tank internal gas discharge pipe 74 is located above the electrical equipment EM in the engine room 13 where the cooling medium tank 71 is installed (see Figure 2). In this case, when fuel gas leaking from the fuel cell 31 and entering the cooling medium tank 71 is discharged from the gas outlet 74a of the cooling tank internal gas discharge pipe 74, the lighter fuel gas (e.g., hydrogen gas) rises, making it less likely for the fuel gas to come into contact with the electrical equipment EM located below. This reduces the risk of the discharged fuel gas being ignited by the electrical equipment EM.

[0076] Furthermore, the ventilation opening 13a of the engine room 13 is located above the gas outlet 74a (see Figure 2). As a result, the lighter fuel gas released from the gas outlet 74a rises directly from the gas outlet 74a and is quickly (efficiently) released to the outside of the engine room 13 through the ventilation opening 13a. Therefore, the risk of ignition of fuel gas by electrical equipment EM inside the engine room 13 can be reliably reduced.

[0077] Furthermore, since the fuel gas supply pipe 32 is a pipe through which fuel gas passes, there is a possibility that fuel gas may leak from the fuel gas supply pipe 32 for some reason. On the other hand, fuel gas leaked from the fuel cell 31 may enter and accumulate in the cooling medium tank 71 via the cooling medium circulation pipe 72. For this reason, it cannot be ruled out that the fuel gas that has accumulated in the cooling medium tank 71 may leak from the cooling medium tank 71 for some reason.

[0078] As in this embodiment, the fuel gas supply piping 32 is located through the engine room 13 where the cooling medium tank 71 is installed, so that the parts of the hull 1 where fuel gas may leak (fuel gas supply piping 32, cooling medium tank 71) are concentrated in the same space (engine room 13). As a result, the area where there is a risk of fuel gas leakage is narrowed compared to, for example, when the cooling medium tank 71 is installed in a location other than the engine room 13. Therefore, the degree of freedom in installation when installing electrical equipment outside the above-mentioned area can be increased. For example, even when installing an air intake fan outside the ventilation opening 13a of the engine room 13 in order to actively ventilate the engine room 13, the area in which the air intake fan can be installed is widened, thus increasing the degree of freedom in installation.

[0079] In this embodiment, as shown in Figure 2, the cooling medium tank 71 is connected to the uppermost part of the cooling medium circulation piping 72. In other words, the cooling medium tank 71 is located at the uppermost part of the circulation path of the cooling medium flowing through the cooling medium circulation piping 72. By defining the positional relationship (connection relationship) between the cooling medium tank 71 and the cooling medium circulation piping 72 in this way, the following effects can be obtained.

[0080] For example, if the cooling medium tank 71 is connected to a part of the cooling medium circulation piping 72 other than the top (for example, the bottom), when the control unit 12a opens the cooling medium internal gas release valve 75 based on the fuel gas detection result from the cooling medium internal gas detector 73, the cooling medium in the cooling medium circulation piping 72 may flow into the cooling medium tank 71 due to its own weight and leak out from the gas outlet 74a of the cooling medium internal gas release piping 74, potentially causing a "cooling medium leak."

[0081] The cooling medium tank 71 is connected to the top of the cooling medium circulation piping 72 and positioned at the top of the cooling medium circulation path. This prevents the cooling medium in the cooling medium circulation piping 72 from flowing into the cooling medium tank 71 due to its own weight, even when the control unit 12a opens the cooling tank internal gas release valve 75. This prevents cooling medium leakage when the cooling tank internal gas release valve 75 is opened.

[0082] Furthermore, when the cooling tank internal gas detector 73 detects that the concentration of fuel gas in the cooling medium tank 71 is below a predetermined standard value, the control unit 12a closes the cooling tank internal gas release valve 75 to seal the cooling medium tank 71 (S3).

[0083] When the operating temperature of the fuel cell 31 becomes high, it may be necessary to supply pressurized water (pressurized cooling medium) to the fuel cell 31 for rapid cooling. For example, when the operating temperature of the fuel cell 31 exceeds 100°C, it is not possible to maintain a liquid state (heat transfer coefficient more than 10 times higher than that of a gaseous state) without a pressurized cooling medium. If there is no leakage of fuel gas into the cooling medium tank 71, it is possible to easily accommodate the supply of such pressurized water by sealing the cooling medium tank 71. In other words, it is possible to pressurize the cooling medium within the cooling medium tank 71 and supply it to the fuel cell 31. In addition, because the cooling medium tank 71 is sealed, it is possible to avoid problems that would occur if the top of the cooling medium tank 71 were constantly open. For example, it is possible to avoid leakage of the cooling medium to the outside of the tank due to the rolling motion of the fuel cell ship SH during navigation, and contamination of the cooling medium in the cooling medium tank 71 with impurities.

[0084] In particular, while the optimal operating temperature for a polymer electrolyte fuel cell 31 is around 80°C, the operating temperature of the fuel cell 31 may exceed 100°C if high-load operation continues. Therefore, the above control, which seals the cooling medium tank 71 and enables the supply of pressurized water when there is no fuel gas leakage into the cooling medium tank 71, is very effective when the operating temperature of the fuel cell 31 is 100°C or higher. In other words, the above control, which seals the cooling medium tank 71 and enables the supply of pressurized water, is very effective when at least one of the temperatures of the cooling medium supplied to the fuel cell 31 and the cooling medium discharged from the fuel cell 31 is 100°C or higher.

[0085] The temperature of the cooling medium supplied to the fuel cell 31 can be monitored by the supply-side cooling medium temperature detection unit 331a shown in Figures 5 and 6. On the other hand, the temperature of the cooling medium discharged from the fuel cell 31 can be monitored by the discharge-side cooling medium temperature detection unit 331b. The supply-side cooling medium temperature detection unit 331a and the discharge-side cooling medium temperature detection unit 331b are composed of temperature sensors such as thermistors.

[0086] [4. Control measures to prevent fuel gas leakage in fuel cells] Figure 5 is a schematic diagram illustrating the main components of the fuel cell ship SH. The fuel cell ship SH may also include a supply-side fuel gas pressure detection unit 332a and a supply-side cooling medium pressure detection unit 333a. The supply-side fuel gas pressure detection unit 332a is a supply-side fuel pressure detection unit that detects the pressure P1 (MPa) of the fuel (e.g., fuel gas) supplied to the fuel cell 31 (from the fuel tank 41). The supply-side cooling medium pressure detection unit 333a detects the pressure P2 (MPa) of the cooling medium supplied to the fuel cell 31 (from the cooling medium tank 71). Both the supply-side fuel gas pressure detection unit 332a and the supply-side cooling medium pressure detection unit 333a are composed of pressure sensors.

[0087] It is desirable that the control unit 12a stops power generation of the fuel cell 31 when the pressure P1 of the fuel (e.g., fuel gas) becomes greater than the pressure P2 of the cooling medium, based on the detection results of the supply-side fuel gas pressure detection unit 332a and the supply-side cooling medium pressure detection unit 333a.

[0088] If P1 > P2, there is a possibility that fuel may leak and mix with the cooling medium on the fuel gas supply side (anode inlet side) of the fuel cell 31. If P1 > P2, stopping the power generation of the fuel cell 31 can suppress the leakage of fuel to the cooling medium on the fuel supply side of the fuel cell 31.

[0089] Figure 6 is a schematic diagram illustrating other components of the main parts of the fuel cell ship SH. In addition to the supply-side fuel gas pressure detection unit 332a and supply-side cooling medium pressure detection unit 333a shown in Figure 5, the fuel cell ship SH may further include an exhaust-side fuel gas pressure detection unit 332b and an exhaust-side cooling medium pressure detection unit 333b. The exhaust-side fuel gas pressure detection unit 332b is an exhaust-side fuel pressure detection unit that detects the pressure P3 (MPa) of the fuel (e.g., fuel gas) discharged from the fuel cell 31. The exhaust-side cooling medium pressure detection unit 333b detects the pressure P4 (MPa) of the cooling medium discharged from the fuel cell 31. Both the exhaust-side fuel gas pressure detection unit 332b and the exhaust-side cooling medium pressure detection unit 333b are composed of pressure sensors.

[0090] Here, the difference between the pressure P1 of the fuel (e.g., fuel gas) detected by the supply-side fuel gas pressure detection unit 332a and the pressure P2 of the cooling medium detected by the supply-side cooling medium pressure detection unit 333a is defined as the first pressure difference Pd1 (MPa). Furthermore, the difference between the pressure P3 of the fuel (e.g., fuel gas) detected by the discharge-side fuel gas pressure detection unit 332b and the pressure P4 of the cooling medium detected by the discharge-side cooling medium pressure detection unit 333b is defined as the second pressure difference Pd2 (MPa).

[0091] It is desirable for the control unit 12a to stop power generation from the fuel cell 31 when at least one of the first pressure difference Pd1 and the second pressure difference Pd2 exceeds a predetermined value Pth (MPa).

[0092] When Pd1 ≥ Pth, that is, for example (P1-P2) ≥ Pth, the fuel supply pressure is too high compared to the cooling medium supply pressure, which may cause fuel to leak and mix with the cooling medium at the fuel supply side (anode inlet side) of the fuel cell 31. On the other hand, when Pd2 ≥ Pth, that is, for example (P3-P4) ≥ Pth, the fuel discharge pressure is too high compared to the cooling medium discharge pressure, which may cause fuel to leak and mix with the cooling medium at the fuel discharge side (anode outlet side) of the fuel cell 31.

[0093] By stopping the power generation of the fuel cell 31 when at least one of the conditions Pd1≧Pth and Pd2≧Pth is satisfied, it is possible to suppress the situation in which fuel leaks to the cooling medium side at at least one of the fuel supply side and discharge side of the fuel cell 31.

[0094] In this embodiment, a gaseous fuel gas is used as the fuel supplied from the fuel tank 41 to the fuel cell 31. However, the fuel is not limited to a gas and may be a liquid. If a liquid fuel is used, and it leaks from the piping, the leaked liquid fuel will vaporize and become a gas (fuel gas).

[0095] Although embodiments of the present invention have been described above, the scope of the present invention is not limited thereto, and it can be expanded or modified without departing from the spirit of the invention. [Industrial applicability]

[0096] This invention can be used, for example, in fuel cell ships. [Explanation of Symbols]

[0097] 1. Hull 6 Propulsion device 7. Cooling System 12a Control Unit 13. Engine room (compartment where cooling medium tanks are installed) 13a Ventilation vent 31 Fuel Cell 32 Fuel gas supply piping (fuel supply piping) 41 Fuel tank 71 Cooling medium tank 72 Coolant circulation piping 73 Cooling tank internal gas detector 74 Cooling tank internal gas discharge piping 74a Gas outlet 75 Cooling tank internal gas release valve 332a Supply-side fuel gas pressure detection unit (supply-side fuel pressure detection unit) 333a Supply side cooling medium pressure detection unit 332b Exhaust-side fuel gas pressure detection unit (exhaust-side fuel pressure detection unit) 333b Discharge side cooling medium pressure detection unit EM Electrical Equipment SH fuel cell ship

Claims

1. A power generation system equipped with a fuel cell that generates electricity through the electrochemical reaction of fuel, The system comprises a cooling system for cooling the fuel cell and an oxidizer gas piping, The cooling system is, A cooling medium tank for containing the cooling medium, It has a cooling tank internal gas discharge pipe connected to the cooling medium tank, A power generation system in which the gas outlet of the cooling tank's internal gas discharge piping is located above the inlet of the oxidizer gas piping.

2. The fuel cell is installed in the fuel cell compartment. The fuel cell compartment is equipped with a battery compartment exhaust port, The inlet portions of the cooling tank internal gas discharge piping and the oxidizer gas piping are located outside the fuel cell compartment. The power generation system according to claim 1, wherein, in the height direction, the battery compartment exhaust port is located between the gas outlet and the inlet of the oxidizer gas piping.

3. A fuel tank for storing the aforementioned fuel, The system further comprises a fuel supply pipe that supplies the fuel from the fuel tank to the fuel cell, The power generation system according to claim 1 or 2, wherein the fuel supply piping passes through a cooling medium tank installation compartment where the cooling medium tank is installed.

4. The cooling system further includes piping for circulating the cooling medium between the fuel cell and the cooling medium tank, The power generation system according to any one of claims 1 to 3, wherein the cooling medium tank is located at the top of the circulation path of the cooling medium flowing through the cooling medium circulation piping.

5. A supply-side fuel pressure detection unit for detecting the pressure of the fuel supplied to the fuel cell, A supply-side cooling medium pressure detection unit detects the pressure of the cooling medium supplied to the fuel cell, The power generation system according to any one of claims 1 to 4, further comprising: a control unit that stops power generation of the fuel cell when the pressure of the fuel becomes greater than the pressure of the cooling medium.

6. A supply-side fuel pressure detection unit for detecting the pressure of the fuel supplied to the fuel cell, A supply-side cooling medium pressure detection unit detects the pressure of the cooling medium supplied to the fuel cell, A discharge-side fuel pressure detection unit that detects the pressure of the fuel discharged from the fuel cell, A discharge-side cooling medium pressure detection unit for detecting the pressure of the cooling medium discharged from the fuel cell, It comprises a control unit and, The difference between the pressure of the fuel detected by the supply-side fuel pressure detection unit and the pressure of the cooling medium detected by the supply-side cooling medium pressure detection unit is defined as the first pressure difference. When the difference between the fuel pressure detected by the discharge-side fuel pressure detection unit and the cooling medium pressure detected by the discharge-side cooling medium pressure detection unit is defined as the second pressure difference, The power generation system according to any one of claims 1 to 4, wherein the control unit stops power generation of the fuel cell when at least one of the first pressure difference and the second pressure difference exceeds a predetermined value.

7. The cooling system is, A cooling tank internal gas detector installed inside the cooling medium tank, The system further includes a cooling tank internal gas release valve installed in the cooling tank internal gas release piping, The power generation system further comprises a discharge valve control unit that controls the opening and closing of the gas discharge valve inside the cooling tank, The power generation system according to any one of claims 1 to 6, wherein the discharge valve control unit closes the internal gas discharge valve of the cooling tank to seal the cooling medium tank when the internal gas detector of the cooling tank detects that the concentration of fuel gas, which is the gaseous state of the fuel in the cooling medium tank, is below a predetermined standard value.

8. The power generation system according to claim 7, wherein at least one of the temperature of the cooling medium supplied to the fuel cell and the temperature of the cooling medium discharged from the fuel cell is 100°C or higher.

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