Fuel cell system

Abstract

To efficiently start a plurality of power generation units with a simple configuration, in a fuel cell system including the plurality of power generation units generating power by ammonia decomposition hydrogen.SOLUTION: A fuel cell system includes a plurality of power generation units each including a power generation module having a fuel cell and a combustion unit, a fuel supply system capable of supplying a fuel gas containing ammonia to the power generation module, and a fuel electrode off-gas line through which fuel electrode off-gas having passed through a fuel electrode of the fuel cell is supplied to at least the combustion unit, and a supply line that is provided in some of the plurality of power generation units and supplies some of the fuel electrode off-gas flowing through the fuel electrode off-gas line of some of the power generation units to the combustion unit of the other power generation units.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This specification discloses a fuel cell system. [Background technology]

[0002] In a conventional fuel cell system including a solid oxide fuel cell having a cell with a fuel electrode on one side of a solid electrolyte and an air electrode on the other side, in which ammonia is supplied to the fuel electrode and an oxidizing gas is supplied to the air electrode to generate electricity, it has been proposed to supply hydrogen-rich gas to the fuel electrode before starting power generation, and when power generation starts, stop supplying hydrogen-rich gas to the fuel electrode and supply ammonia as fuel gas to the fuel electrode (see, for example, Patent Document 1).

[0003] Another proposed fuel cell includes a first hydrogen generation unit for startup, which includes a heater and a first catalyst that generates hydrogen to be supplied to the fuel electrode by contacting ammonia with the first catalyst, and a second hydrogen generation unit for power generation, which includes a second catalyst that generates hydrogen to be supplied to the fuel electrode by contacting ammonia with the second catalyst and exchanges heat between the ammonia in contact with the second catalyst and the heat of the off-gas or heat obtained by combustion of the off-gas (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-204418 [Patent Document 2] Patent Publication No. 2021-128904 Summary of the Invention [Problem to be solved by the invention]

[0005] When a system is configured with multiple power generation units, the fuel cell system described in Patent Document 1 requires a supply of hydrogen gas to each of the multiple power generation modules in order to start up the multiple power generation units. For example, if hydrogen gas stored in a tank is used to supply hydrogen gas, energy loss occurs due to compression of the hydrogen gas, which reduces the efficiency of the entire system. Furthermore, the fuel cell system described in Patent Document 2 requires a startup hydrogen generator in each of the multiple power generation modules in order to start up the multiple power generation units, which complicates the configuration and increases costs.

[0006] A primary object of the present disclosure is to provide a fuel cell system having a plurality of power generation units that generate electricity using hydrogen generated by ammonia decomposition, and to enable efficient startup of the plurality of power generation units with a simple configuration. [Means for solving the problem]

[0007] The present disclosure has adopted the following means to achieve the above-mentioned main object.

[0008] The fuel cell system disclosed herein comprises a power generation module having a fuel cell that generates electricity based on ammonia decomposition hydrogen supplied to an anode and an oxidizer supplied to an oxidizer electrode, and a combustion section that combusts combustible gas; a fuel supply system capable of supplying fuel gas containing ammonia to the power generation module; and an anode off-gas line that supplies anode off-gas that has passed through the anode of the fuel cell to at least the combustion section; and a supply line provided in some of the power generation units, that supplies a portion of the anode off-gas flowing through the anode off-gas line of one of the power generation units to the combustion section of the other power generation units.

[0009] In the fuel cell system disclosed herein, anode off-gas from some power generating units in power generation operation is combusted in the combustion section of the other power generating units to warm up the power generating modules of the other power generating units, thereby enabling a fuel cell system capable of efficiently starting up multiple power generating units with a simple configuration. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic diagram of a fuel cell system according to an embodiment of the present invention; [Figure 2] 10 is a flowchart illustrating an example of a startup process. [Figure 3] FIG. 10 is a schematic diagram of a fuel cell system according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present disclosure will be described with reference to the drawings.

[0012] Fig. 1 is a schematic diagram of a fuel cell system 1 of this embodiment. As shown in Fig. 1, the fuel cell system 1 of this embodiment includes a plurality of power generation units 10A, 10B and a control device 60 that controls the entire system.

[0013] Each of the power generation units 10A, 10B includes a power generation module 20 that generates power using ammonia cracked hydrogen as fuel gas, and various auxiliary devices required for the operation of the power generation module 20, as shown in FIG.

[0014] The power generation module 20 includes a fuel cell stack 21, a decomposer 22, a combustor 23, and heat exchangers 24, 25, and 26, all of which are housed in a thermally insulating module case 28. Various auxiliary equipment includes a fuel supply system 30, an air supply system 40, a circulation system 50, etc., which are provided for each of the power generation units 10A and 10B.

[0015] The fuel cell stack 21 includes a plurality of solid oxide unit cells, each including an electrolyte, a fuel electrode disposed on one side of the electrolyte, and an oxidizer electrode disposed on the other side of the electrolyte. The fuel cell stack 21 operates in a high-temperature environment of, for example, 600 to 800°C, so the electrolyte, fuel electrode, and oxidizer electrode are made of ceramic materials. The fuel electrode is made of a cermet made of ceramic and a metal such as nickel that has catalytic properties. Each fuel cell stack 21 generates electricity by reacting hydrogen contained in the fuel gas with oxygen contained in the oxidizer gas. A temperature sensor (not shown) is installed near the fuel cell stack 21. The temperature sensor detects a temperature (stack temperature) that correlates with the temperature of the fuel cell stack 21.

[0016] One end of fuel electrode inlet pipe 21a is connected to the fuel electrode inlet of fuel cell stack 21, and the other end of fuel electrode inlet pipe 21a is connected to fuel supply system 30. Furthermore, one end of oxidizer electrode inlet pipe 21b is connected to the oxidizer electrode inlet of fuel cell stack 21, and the other end of oxidizer electrode inlet pipe 21b is connected to air supply system 40.

[0017] One end of a fuel electrode outlet pipe 21c is connected to the fuel electrode outlet of the fuel cell stack 21, and the other end of the fuel electrode outlet pipe 21c is connected to the circulation system 50. Furthermore, one end of an oxidizer electrode outlet pipe 21d is connected to the oxidizer electrode outlet of the fuel cell stack 21, and the other end of the oxidizer electrode outlet pipe 21d is connected to the combustor 23. Furthermore, the combustor 23 is connected to a combustion fuel gas pipe 53 and a combustion exhaust gas pipe 21e.

[0018] The decomposer 22 is installed in the anode inlet pipe 21a and has a decomposition catalyst that decomposes ammonia supplied from the fuel supply system 30 into hydrogen (ammonia decomposition hydrogen) and nitrogen in the power generation module 20 under a high-temperature environment. Ruthenium or nickel, for example, is used as the decomposition catalyst.

[0019] Heat exchanger 24 is installed upstream of decomposer 22 in anode inlet pipe 21a inside power generation module 20, and performs heat exchange between fuel gas (ammonia) from fuel supply system 30 flowing through anode inlet pipe 21a and fuel exhaust gas from combustor 23 flowing through combustion exhaust gas pipe 21e. Heat exchanger 25 is installed in oxidizer electrode inlet pipe 21b inside power generation module 20, and performs heat exchange between air from air supply system 40 flowing through oxidizer electrode inlet pipe 21b and fuel exhaust gas from combustor 23 flowing through combustion exhaust gas pipe 21e. Heat exchanger 26 is installed downstream of heat exchanger 25 in oxidizer electrode inlet pipe 21b, and performs heat exchange between air flowing through oxidizer electrode inlet pipe 21b and fuel off-gas flowing through anode outlet pipe 21c.

[0020] Ammonia decomposition hydrogen, which is supplied as a fuel gas from a fuel supply system 30 via a decomposer 22, is introduced into the fuel electrode of the fuel cell stack 21, and air, which is supplied as an oxidizer gas from an air supply system 40, is introduced into the oxidizer electrode of the fuel cell stack 21. At the oxidizer electrode, oxide ions (O 2- ) is generated, and the oxide ions permeate the electrolyte and react with hydrogen from the ammonia decomposition at the anode, generating electrical energy. Anode off-gas (residual fuel gas) not used in the electrochemical reaction (power generation) at the anode of each unit cell flows through anode outlet piping 21c and exchanges heat with air flowing through oxidizer electrode inlet piping 21b in heat exchanger 26 before being discharged outside module case 28. The anode off-gas discharged outside module case 28 is supplied to circulation system 50 through anode off-gas piping 51, where at least a portion of the water vapor contained in the anode off-gas is removed in condenser 52. The anode off-gas that has passed through condenser 52 is then distributed to combustion fuel gas piping 53 and reflux piping 54. The anode off-gas distributed to combustion fuel gas piping 53 is supplied to combustor 23, and the anode off-gas distributed to reflux piping 54 is refluxed to fuel supply system 30.

[0021] The anode off-gas introduced into combustor 23 is a flammable gas containing hydrogen. It is mixed with oxidizer off-gas containing oxygen introduced into combustor 23 from the oxidizer electrode through oxidizer electrode outlet pipe 21d, and the mixed gas is combusted in combustor 23. The combustion of the anode off-gas maintains fuel cell stack 21 at an appropriate temperature. Although not shown, combustor 23 is provided with an ignition device for igniting the mixed gas introduced into combustor 23 during startup processing, and a temperature sensor for detecting the internal temperature of combustor 23. In combustor 23, combustion of the mixed gas generates combustion exhaust gas. The generated combustion exhaust gas flows through combustion exhaust gas pipe 21e, exchanges heat with fuel gas (ammonia) supplied from fuel supply system 30 in heat exchanger 24, and exchanges heat with oxidizer gas (air) supplied from air supply system 40 in heat exchanger 25, before being discharged to the outside air.

[0022] Each fuel supply system 30 of power generation units 10A, 10B includes a fuel supply pipe 31 having one end connected to an ammonia supply source such as an ammonia tank and the other end connected to anode inlet pipe 21a, and a fuel blower 32 installed in fuel supply pipe 31. By operating fuel blower 32, ammonia from the ammonia supply source is pumped (supplied) to the corresponding power generation module 20. In addition, a flow meter 33 and an on-off valve 34 are installed in fuel supply pipe 31. Flow meter 33 detects the flow rate per unit time of fuel gas (ammonia) flowing through fuel supply pipe 31. The ammonia introduced into power generation module 20 is heated by heat exchange with combustion exhaust gas in heat exchanger 24, and then decomposed into hydrogen (ammonia decomposition hydrogen) and nitrogen in decomposer 22. The ammonia is then supplied to the anode of fuel cell stack 21.

[0023] The fuel supply system 30 of one of the power generation units 10A also has a hydrogen supply unit 35 that supplies hydrogen from a hydrogen supply source such as a hydrogen tank to the fuel supply pipe 31. When starting up the power generation unit 10A, the hydrogen supply unit 35 supplies start-up hydrogen to the power generation module 20 of the power generation unit 10 and burns the hydrogen in the combustor 23 to warm up the power generation module 20 (fuel cell stack 21). The hydrogen supply unit 35 has a hydrogen supply pipe 36 that has one end connected to the hydrogen supply source and the other end connected to the fuel supply pipe 31 between the fuel blower 32 and the flow meter 33. A flow meter 37 and an on-off valve 38 are installed in the hydrogen supply pipe 36.

[0024] The fuel supply system 30 of the other power generation unit 10B does not have a hydrogen supply unit 35. In this embodiment, when starting up the fuel cell system 1, one power generation unit 10A is started up first using hydrogen supplied from the hydrogen supply unit 35 as a start-up fuel gas to transition to a power generation state, and then the anode off-gas discharged from the one power generation unit 10A during power generation operation is supplied as a start-up fuel gas to the fuel supply system 30 (combustor 23) of the other power generation unit 10B to start up the other power generation unit 10B.

[0025] Each air supply system 40 of the power generation units 10A, 10B has an air supply pipe 41 connected to the corresponding power generation module 20 and an air blower 42 installed in the air supply pipe 41. By operating the air blower 42, air is drawn into the air supply pipe 41, and the drawn air is pressure-fed (supplied) to the power generation module 20 as oxidant gas. In addition, a flow meter 43 is installed in each air supply pipe 41. The flow meter 43 detects the flow rate per unit time of air flowing through the air supply pipe 41. The air introduced into the power generation module 20 is heated by sequentially exchanging heat with the combustion exhaust gas and the anode off-gas in the heat exchangers 25, 26, and then supplied to the oxidant electrode of the fuel cell stack 21.

[0026] Each circulation system 50 of power generation units 10A, 10B includes an anode off-gas pipe 51 connected to an anode outlet pipe 21c of the corresponding power generation module 20, a condenser 52 installed in the anode off-gas pipe 51, and a combustion fuel gas pipe 53 branching off from the anode off-gas pipe 51 downstream of the condenser 52 and connected to the combustor 23 of the corresponding power generation module 20. Each circulation system 50 of power generation units 10A, 10B also includes a return pipe 54 branching off from the anode off-gas pipe 51 downstream of the condenser 52 and connected to the upstream side of the fuel blower 32 in the fuel supply pipe 31 of the corresponding power generation module 20, and an orifice 55 formed in the return pipe 54.

[0027] Anode off-gas discharged from the anode outlet of fuel cell stack 21 of power generation module 20 passes through anode off-gas piping 51 and condenses in condenser 52 through heat exchange with cooling water, condensing the water vapor contained in the anode off-gas. The anode off-gas that has passed through condenser 52 is then distributed to combustion fuel gas piping 53 and reflux piping 54. The anode off-gas distributed to combustion fuel gas piping 53 is supplied to the combustor 23 of the corresponding power generation module 20. Meanwhile, the anode off-gas distributed to reflux piping 54 is drawn into fuel supply piping 31 by negative pressure generated by driving fuel blower 32, introduced into power generation module 20, and supplied to the anode of fuel cell stack 21. Note that although an orifice 55 is formed in reflux piping 54, a solenoid valve may be installed instead of orifice 55.

[0028] The circulation system 50 of one power generation unit 10A also has a startup fuel gas supply pipe 56 that branches off from the anode off-gas piping 51 downstream of the condenser 52 and is connected to the fuel supply pipe 31 of the other power generation unit 10B upstream of the fuel blower 32. An on-off valve 57 and a flow meter 58 are installed in the startup fuel gas supply pipe 56.

[0029] The DC power generated in each fuel cell stack 21 of the power generation units 10A, 10B is converted by a power conditioner (not shown) and supplied to a load. In this embodiment, each fuel cell stack 21 is connected in parallel to the load. The power conditioner has a DC / DC converter and an inverter, and converts the DC power from the fuel cell stack 21 into AC power of a voltage (e.g., AC 200 V) that can be connected to a grid power supply, and outputs the converted AC power. A power supply board (not shown) is also connected to the power conditioner, and the power supply board converts the power from each fuel cell stack 21 into DC power suitable for driving various auxiliary devices and the control device 60, and supplies the converted power to each of them.

[0030] Although not shown, the control device 60 is configured as a microprocessor centered around a CPU, and in addition to the CPU, includes a ROM for storing processing programs, a RAM for temporarily storing data, an EEPROM, input / output ports, and communication ports. The control device 60 receives, via its input ports, the stack temperature from a temperature sensor installed near the fuel cell stack 21 of the power generation module 20, the combustion section temperature from a temperature sensor installed in the combustor 23 of the power generation module 20, the stack current from a current sensor attached to the output terminals of the fuel cell stack 21 of the power generation module 20, the stack voltage from a voltage sensor attached between the output terminals of the fuel cell stack 21 of the power generation module 20, the fuel flow rate from a flow meter 33 installed in the fuel supply pipe 31, the hydrogen flow rate from a flow meter 37 installed in the hydrogen supply pipe 36, the air flow rate from a flow meter 43 installed in the air supply pipe 41, and the fuel flow rate from a flow meter 58 installed in the startup fuel gas supply pipe 56. In addition, the control device 60 outputs control signals to the fuel blower 32 and on-off valves 34 and 38 of the fuel supply system 30, a control signal to the air blower 42 of the air supply system 40, and a control signal to the on-off valve 57 of the circulation system 50 via output ports.

[0031] Next, the operation of the fuel cell system 1 of this embodiment configured as described above, particularly the operation when starting up the system, will be described. When a request to start up the fuel cell system 1 is received from a higher-level system, the control device 60 sequentially controls the corresponding various auxiliaries, warms up the corresponding power generation modules 20 (fuel cell stacks 21), and starts up the multiple power generation units 10A, 10B. As described above, the startup of the multiple power generation units 10A, 10B is performed by first starting up one power generation unit 10A and transitioning it to a power generation state, and then starting up the other power generation unit 10B and transitioning it to a power generation state.

[0032] In the power generation state, the control device 60 sets a target fuel flow rate and a target air flow rate based on the power required for the system, and controls the corresponding fuel blower 32 and air blower 42 based on the set target values. Specifically, the control device 60 controls the drive of the fuel blower 32 by feedback control based on the difference between the target fuel flow rate and the fuel flow rate detected by the flow meter 33, and controls the drive of the air blower 42 by feedback control based on the difference between the target air flow rate and the air flow rate detected by the flow meter 43.

[0033] Next, the details of the startup process will be described. Fig. 2 is a flowchart showing an example of the startup process executed by the control device 60.

[0034] When the startup process is executed, the control device 60 first closes the on-off valve 34 of the power generating unit 10A and opens the on-off valve 38 to control the fuel blower 32 and the air blower 42 so that hydrogen from the hydrogen supply unit 35 and air from the air supply system 40 are supplied to the combustor 23 of the power generating module 20 of the power generating unit 10A (hereinafter, the power generating module 20 of the power generating unit 10A will be referred to as power generating module A, and the power generating module 20 of the power generating unit 10B will be referred to as power generating module B) (step S100). The hydrogen introduced from the hydrogen supply unit 35 to the power generating module A is supplied to the combustor 23 via the anode inlet pipe 21a, the anode of the fuel cell stack 21, the anode outlet pipe 21c, the anode off-gas pipe 51, and the combustion fuel gas pipe 53 in this order. Furthermore, the air introduced into the power generation module A from the air supply system 40 is supplied to the combustor 23 via the oxidizer electrode inlet pipe 21b, the oxidizer electrode of the fuel cell stack 21, and the oxidizer electrode outlet pipe 21d in that order. Next, the control device 60 combusts a mixed gas of hydrogen and air in the combustor 23 of the power generation module A, and warms up the power generation module A (fuel cell stack 21) with the combustion heat (step S102). The control device 60 then determines whether the warm-up of the power generation module A has been completed (step S104). This process is performed by determining whether the stack temperature of the power generation module A is equal to or higher than a predetermined temperature. When the control device 60 determines that the warm-up of the power generation module A is complete, it closes the on-off valve 38 of the power generation module A and opens the on-off valve 34, controls the fuel blower 32 and the air blower 42 so that ammonia as fuel gas from the fuel supply system 30 and air from the air supply system 40 are supplied to the fuel cell stack 21 of the power generation module A (step S106), and starts power generation of the power generation module A (step S108).

[0035] When power generation in power generation module A is started, control device 60 executes an increase control, which sets a target fuel flow rate to increase the amount of ammonia supplied to fuel cell stack 21 of power generation module A and controls fuel blower 32 of power generation module A (step S110). The increase control is a process for making up for a shortage of anode off-gas returned to fuel cell stack 21 of power generation module A and a shortage of anode off-gas supplied to combustor 23, in order to start power generation unit 10B using a portion of the anode off-gas from power generation module A of power generation unit 10A that is in power generation operation.

[0036] Next, the control device 60 controls the fuel blower 32 to open the on-off valve 57 and supply the anode off-gas from the power generation module A to the fuel supply pipe 31 of the power generation unit 10B via the startup fuel gas supply pipe 56, and also controls the air blower 42 to supply air from the air supply system 40 to the combustor 23 (step S112). The anode off-gas supplied to the fuel supply pipe 31 of the power generation unit 10B is introduced into the power generation module B and supplied to the combustor 23 via the anode inlet pipe 21a, the anode of the fuel cell stack 21, the anode outlet pipe 21c, the anode off-gas pipe 51, and the combustion fuel gas pipe 53 in this order. Next, the control device 60 combusts the mixed gas of the anode off-gas and air in the combustor 23 of the power generation module B, and warms up the power generation module B (fuel cell stack 21) using the combustion heat (step S114). The control device 60 then determines whether the warm-up of the power generation module B has been completed (step S116). This process is performed by determining whether the stack temperature of power generation module B is equal to or higher than a predetermined temperature. When the control device 60 determines that the warm-up of power generation module B is complete, it closes the on-off valve 57 and opens the on-off valve 34 of power generation module B, and controls the fuel blower 32 and the air blower 42 so that ammonia as fuel gas from the fuel supply system 30 and air from the air supply system 40 are supplied to the fuel cell stack 21 of power generation module B (step S118), thereby starting power generation in power generation module B (step S120). Then, the control device 60 cancels the increase in the amount of ammonia supplied to power generation module A (increase control) (step S122), and ends the startup process.

[0037] In the fuel cell system 1 of the present embodiment described above, one power generating unit 10A is started up first using hydrogen supplied from the hydrogen supply unit 35 as start-up fuel gas to transition to a power generating state, and then the anode off-gas discharged from one power generating unit 10A during power generating operation is supplied as start-up fuel gas to the fuel supply system 30 (combustor 23) of the other power generating unit 10B to start up the other power generating unit 10B. As a result, one hydrogen supply unit 35 is sufficient to start up the multiple power generating units 10A, 10B, and the fuel cell system 1 can be configured to efficiently start up the multiple power generating units 10A, 10B with a simple configuration.

[0038] In the above-described embodiment, the power generating unit 10A includes a hydrogen supply unit 35 in the fuel supply system 30, while the power generating unit 10B does not include a hydrogen supply unit 35 in the fuel supply system 30. However, as shown in FIG. 3 , the power generating unit 10A may include a cracker 135 in the fuel supply pipe 31, while the power generating unit 10B may not include a cracker 135 in the fuel supply pipe 31. The cracker 135 includes a cracking catalyst similar to that of the cracker 22, as well as a heater 136 as a heat source. The heater 136 may be an electric heater or a burner device. In the fuel cell system 101 according to the other embodiment, in the power generating unit 10A, which is started up first, ammonia supplied from an ammonia supply source to the fuel supply pipe 31 is decomposed into hydrogen and nitrogen in the cracker 135 and then supplied to the power generating module A to warm up the power generating module A. Then, after starting up the power generation unit 10A and transitioning to a power generation state, the anode off-gas discharged from the power generation unit 10A during power generation operation is supplied to the power generation module B of the power generation unit 10B to warm up the power generation module B and start up the power generation unit 10B. This means that one decomposer 135 is sufficient to start up the multiple power generation units 10A and 10B, making it possible to simplify the system configuration.

[0039] In the above-described embodiment, the startup fuel gas supply pipe 56 branches off from the anode off-gas piping 51 of the power generation unit 10A and is connected to the fuel supply pipe 31 of the other power generation unit 10B, but it may also be connected directly to the combustor 23 of the other power generation unit 10B.

[0040] In the above-described embodiment, the fuel cell system 1 includes two power generating units 10A and 10B. However, the fuel cell system 1 may include three or more power generating units 10A, 10B, 10C, etc. In this case, the startup fuel gas supply pipe 56 may branch from the anode off-gas pipe 51 of the power generating unit 10A and be connected to all of the other power generating units 10B, 10C, etc. The startup fuel gas supply pipe 56 may also be configured to sequentially connect adjacent power generating units 10A, 10B, and 10C in series. For example, if the fuel cell system 1 includes three power generating units 10A, 10B, and 10C, the fuel cell system 1 may include a startup fuel gas supply pipe 56 that branches from the anode off-gas pipe 51 of the power generating unit 10A and is connected to the fuel supply pipe 31 of the power generating unit 10B, and a startup fuel gas supply pipe that branches from the anode off-gas pipe 51 of the power generating unit 10B and is connected to the fuel supply pipe 31 of the power generating unit 10C. In addition, when the fuel cell system 1 has three or more power generation units 10A, 10B, 10C, etc., the number of hydrogen supply units 35 and decomposers 135 does not necessarily have to be one, and two or more may be provided as long as the number is less than the number of power generation units.

[0041] In the above-described embodiment, each fuel cell stack 21 performs a power generation operation by reacting hydrogen with oxygen contained in the air. However, the fuel cell stack 21 may be a reversible operation solid oxide cell stack and may have an FC mode in which a power generation operation is performed, and an EC mode in which an electrolysis operation is performed in which hydrogen is produced by high-temperature steam electrolysis while power is supplied from a power source. Note that the power source may be a grid power supply, a renewable energy device such as a solar power generation device, a storage battery, or the like.

[0042] The above describes the forms for implementing the present disclosure using embodiments, but the present disclosure is not limited to these embodiments in any way, and it goes without saying that the present disclosure can be implemented in various forms within the scope that does not deviate from the gist of the present disclosure. [Industrial Applicability]

[0043] The present disclosure is applicable to the fuel cell system manufacturing industry and the like. [Explanation of symbols]

[0044] 10 fuel cell system, 10A, 10B power generation unit, 20 power generation module, 21 fuel cell stack (fuel cell), 23 combustor (combustion section), 30 fuel supply system, 35 hydrogen supply section, 51 anode off-gas piping (anode off-gas line), 53 combustion fuel gas piping (anode off-gas line), 56 startup fuel gas supply pipe (supply line), 60 control device (startup control section), 135 decomposer (ammonia decomposition section), 136 heater (heating section).

Claims

1. a plurality of power generation units each including a power generation module having a fuel cell that generates power based on ammonia decomposition hydrogen supplied to an anode and an oxidant supplied to an oxidant electrode, and a combustion section that combusts combustible gas; a fuel supply system that can supply a fuel gas containing ammonia to the power generation module; and an anode off-gas line that supplies anode off-gas that has passed through the anode of the fuel cell to at least the combustion section; a supply line provided in some of the power generation units among the plurality of power generation units, for supplying a portion of the anode off-gas flowing through the anode off-gas line of the some of the power generation units to the combustion section of the other power generation units; A fuel cell system comprising:

2. 2. The fuel cell system according to claim 1, a start-up control unit that, when starting up the plurality of power generation units, starts up the power generation modules of some of the power generation units first, and supplies anode off-gas from the power generation modules of some of the power generation units that have completed start-up to the fuel supply system of the other power generation units that have not completed start-up via the supply line, thereby starting up the power generation modules of the other power generation units; Fuel cell system.

3. 3. The fuel cell system according to claim 2, the startup control unit increases the amount of fuel gas supplied from the fuel supply system to the power generation modules of the partial power generation units after startup of the power generation modules of the partial power generation units is completed until startup of the power generation modules of the other power generation units is completed. Fuel cell system.

4. 4. The fuel cell system according to claim 2 or 3, the fuel supply system of the part of the power generation units has an ammonia decomposition unit including a decomposition catalyst that decomposes ammonia into hydrogen and nitrogen and a heating unit, or a hydrogen supply unit that supplies hydrogen; the fuel supply system of the other power generation unit does not have the ammonia decomposition unit or the hydrogen supply unit; Fuel cell system.

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