Fuel cell system

Abstract

A fuel cell system (100) according to the present disclosure is provided with: a plurality of first fuel cell units (10); a recovery device (30) that recovers a hydrogen-containing gas (G1) which is discharged from each of the plurality of first fuel cell units (10); a hydrogen-containing gas supply device (40) that increases the pressure of the hydrogen-containing gas (G2), which has been recovered by the recovery device (30); and a controller (50) that controls the hydrogen-containing gas supply device (40) so that the hydrogen-containing gas (G2), the pressure of which has been increased, is supplied to at least one fuel cell unit that is selected from the group consisting of at least one of the plurality of first fuel cell units (10) and a second fuel cell unit (20) that is different from the plurality of first fuel cell units (10).

Description

fuel cell system

[0001] The present disclosure relates to fuel cell systems.

[0002] As a configuration for obtaining a high amount of power generation, a fuel cell system equipped with a plurality of fuel cells has been proposed. For example, Patent Document 1 describes a fuel cell system equipped with a plurality of fuel cells connected in parallel, in which air containing oxygen is supplied to each of the plurality of fuel cells through a common pipe, and fuel gas containing hydrogen is supplied to each of the plurality of fuel cells through another common pipe.

[0003] Japanese Patent Application Laid-Open No. 2000-40518

[0004] The present disclosure provides a technique suitable for improving the power generation efficiency of a fuel cell system equipped with multiple fuel cells.

[0005] The fuel cell system of the present disclosure comprises: a plurality of first fuel cell units; a recovery device that recovers hydrogen-containing gas discharged from each of the plurality of first fuel cell units; a hydrogen-containing gas supply device that pressurizes the hydrogen-containing gas recovered by the recovery device; and a controller that controls the hydrogen-containing gas supply device so that the pressurized hydrogen-containing gas is supplied to at least one selected from the group consisting of at least one of the plurality of first fuel cell units and a second fuel cell unit different from the plurality of first fuel cell units.

[0006] The technology according to the present disclosure is suitable for improving the power generation efficiency of a fuel cell system equipped with a plurality of fuel cells.

[0007] A configuration diagram showing an example of a fuel cell system according to an embodiment. A configuration diagram showing another example of a fuel cell system according to an embodiment. A configuration diagram showing yet another example of a fuel cell system according to an embodiment. A configuration diagram showing an example of a fuel cell system according to a modified example.

[0008] (Knowledge, etc., that forms the basis of the present disclosure) Pure hydrogen fuel cells that use hydrogen gas as fuel gas are known (for example, Patent Document 1). Pure hydrogen fuel cells are typically supplied with hydrogen gas at a flow rate that exceeds the minimum flow rate required for power generation. This prevents a shortage of hydrogen gas inside the fuel cell and suppresses fuel cell degradation. However, there is a problem in that unreacted hydrogen gas produced during the electrochemical reaction is wasted. For example, with the configuration of the fuel cell system disclosed in Patent Document 1, unreacted hydrogen gas produced in each fuel cell is released outside the system, making it difficult to operate the fuel cell system with high power generation efficiency.

[0009] Therefore, the present inventors have investigated techniques suitable for improving the power generation efficiency of a fuel cell system equipped with a plurality of fuel cells.

[0010] Hereinafter, embodiments will be described in detail with reference to the drawings. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters or redundant descriptions of substantially identical configurations may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art.

[0011] The accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter recited in the claims.

[0012] (Embodiment) Hereinafter, an embodiment will be described with reference to Figs.

[0013] [1-1. Configuration] The fuel cell system of this embodiment comprises a plurality of first fuel cell units 10, a recovery device 30, a hydrogen-containing gas supply device 40, and a controller 50.

[0014] The recovery device 30 recovers the hydrogen-containing gas G1 discharged from each of the plurality of first fuel cell units 10. The hydrogen-containing gas supply device 40 pressurizes the hydrogen-containing gas G2 recovered by the recovery device 30. The controller 50 controls the hydrogen-containing gas supply device 40 so that the pressurized hydrogen-containing gas G2 is supplied to at least one selected from the group consisting of at least one of the plurality of first fuel cell units 10 and at least one second fuel cell unit 20 different from the plurality of first fuel cell units 10.

[0015] FIG. 1 is a configuration diagram showing an example of a fuel cell system according to the present embodiment. In the fuel cell system 100 shown in FIG. 1, a controller 50 controls a hydrogen-containing gas supply device 40 so that pressurized hydrogen-containing gas G2 is supplied to at least one of a plurality of first fuel cell units 10. This configuration makes it possible to effectively utilize unreacted hydrogen produced during electrochemical reactions in the plurality of first fuel cell units 10, thereby reducing fuel gas loss. As a result, the power generation efficiency of the fuel cell system 100 is improved.

[0016] The operating conditions of the fuel cell system 100 may be changed depending on the number of first fuel cell units 10. For example, the greater the number of first fuel cell units 10 that are operated, the greater the pressure required to deliver the hydrogen-containing gas G2. Therefore, the greater the number of first fuel cell units 10 that are operated, the greater the amount of pressure increase in the hydrogen-containing gas supply device 40. The controller 50 may control the hydrogen-containing gas supply device 40 so that the greater the number of first fuel cell units 10 that are operated, the greater the amount of pressure increase.

[0017] 1, the fuel cell system 100 includes first fuel cell units 11, 12, ... 1n as a plurality of first fuel cell units 10. In the example shown in Fig. 1, n is an arbitrary natural number equal to or greater than 3. The same applies to the other examples described below.

[0018] The first fuel cell units 11, 12, . . . 1n are arranged in parallel with one another.

[0019] The multiple first fuel cell units 10 generate electricity using hydrogen gas G0 as fuel gas. The hydrogen gas G0 as fuel gas is pure hydrogen gas. The first fuel cell units 11, 12, ... 1n are pure hydrogen type fuel cells that use pure hydrogen gas as fuel gas. Pure hydrogen gas is a gas that is essentially composed of hydrogen (H2) and may contain unavoidable impurities.

[0020] Each of the first fuel cell units 11, 12, ... 1n includes a first fuel cell stack 10a. The first fuel cell stack 10a generates electricity by receiving an anode gas and a cathode gas. The anode gas is hydrogen gas G0. The cathode gas is an oxygen-containing gas such as air. Examples of fuel cells include polymer electrolyte fuel cells (PEFCs) and solid oxide fuel cells (SOFCs).

[0021] Although not shown, each of the first fuel cell units 11, 12, ... 1n further includes a power conversion device. The power conversion device may include a DC-DC converter and a DC-AC inverter.

[0022] Anode off-gas and cathode off-gas are generated from each of the first fuel cell units 11, 12, ... 1n due to electrochemical reactions in the first fuel cell stack 10a. The anode off-gas is discharged from the anode of the first fuel cell stack 10a. The cathode off-gas is discharged from the cathode of the first fuel cell stack 10a. The anode off-gas is hydrogen-containing gas G1.

[0023] The recovery device 30 recovers the hydrogen-containing gas G1 discharged from each of the first fuel cell units 11, 12, ... 1n. The recovery device 30 includes a tank 30a for storing the recovered hydrogen-containing gas G1.

[0024] The recovery device 30 may further include a concentrator 30b that increases the hydrogen concentration in the recovered hydrogen-containing gas G1. The concentrator 30b selectively concentrates hydrogen contained in the hydrogen-containing gas G1. As the electrochemical reaction progresses in the fuel cell, nitrogen cross-leak occurs from the cathode to the anode. Therefore, the hydrogen-containing gas discharged from the fuel cell contains nitrogen in addition to hydrogen. If the recycling of a hydrogen-containing gas with a low hydrogen concentration is continued for a long period of time, the nitrogen concentration in the hydrogen-containing gas supplied to the fuel cell gradually increases, resulting in a decrease in power generation efficiency. In the fuel cell system 100, even if the hydrogen concentration of the hydrogen-containing gas G1 discharged from each of the first fuel cell units 11, 12, ..., 1n is low, the concentrator 30b can increase the hydrogen concentration. As a result, a hydrogen-containing gas G2 with a high hydrogen concentration can be supplied to the first fuel cell units 11, 12, ..., 1n, thereby further improving the power generation efficiency of the fuel cell system 100.

[0025] The concentrating section 30b may increase the hydrogen concentration by reducing the nitrogen concentration in the hydrogen-containing gas G1.

[0026] The configuration of the concentrating unit 30b is not particularly limited as long as it can increase the hydrogen concentration in the recovered hydrogen-containing gas G1. The concentrating unit 30b may be, for example, one that employs a membrane separation method or an adsorption separation method.

[0027] The concentration section 30b may be connected to the tank 30a or may be incorporated into the tank 30a.

[0028] 1 , the fuel cell system 100 may include a first recovery path L1 that guides the hydrogen-containing gas G1 discharged from each of the first fuel cell units 11, 12, ..., 1n to the recovery device 30. The hydrogen-containing gas G1 discharged from each of the first fuel cell units 11, 12, ..., 1n may be guided to the recovery device 30 by the first recovery path L1.

[0029] The fuel cell system 100 may have a plurality of first sub-recovery paths that merge with the first recovery path L1 to guide the hydrogen-containing gas G1 discharged from each of the first fuel cell units 11, 12, ... 1n to the recovery vessel 30.

[0030] 1, the hydrogen-containing gas G1 discharged from the first fuel cell unit 11 passes through a first sub-recovery path L11 and merges with the first recovery path L1. The hydrogen-containing gas G1 discharged from the first fuel cell unit 12 passes through a first sub-recovery path L12 and merges with the first recovery path L1. The hydrogen-containing gas G1 discharged from the first fuel cell unit In passes through a first sub-recovery path L1n and merges with the first recovery path L1.

[0031] 1 , the fuel cell system 100 may include a second recovery path L2 that guides the hydrogen-containing gas G2 from the recovery device 30 to the hydrogen-containing gas supply device 40. The hydrogen-containing gas G2 discharged from the recovery device 30 may be guided to the hydrogen-containing gas supply device 40 via the second recovery path L2.

[0032] 1 , the fuel cell system 100 may include, as the third recovery path L3, a third recovery path L31 that guides the hydrogen-containing gas G2 from the hydrogen-containing gas supply device 40 to at least one of the plurality of first fuel cell units 11, 12, ..., 1n. The hydrogen-containing gas G2 delivered from the hydrogen-containing gas supply device 40 may be guided to at least one of the first fuel cell units 11, 12, ..., 1n by the third recovery path L31. The hydrogen-containing gas G2 delivered from the hydrogen-containing gas supply device 40 may be guided to all of the first fuel cell units 11, 12, ..., 1n by the third recovery path L31.

[0033] 1, the fuel cell system 100 may further include a hydrogen gas supply path L0. The hydrogen gas supply path L0 may guide hydrogen gas G0 discharged from an external hydrogen storage tank or the like to the first fuel cell unit 11, 12, ..., 1n.

[0034] The fuel cell system 100 may include a plurality of sub-hydrogen gas supply paths branching from the hydrogen gas supply path L0 so as to supply hydrogen gas G0 to each of the first fuel cell units 11, 12, . . . 1n.

[0035] 1, hydrogen gas G0 flowing through the hydrogen gas supply path L0 is supplied to the first fuel cell unit 11 via a sub-hydrogen gas supply path L01. Hydrogen gas G0 flowing through the hydrogen gas supply path L0 is supplied to the first fuel cell unit 12 via a sub-hydrogen gas supply path L02. Hydrogen gas G0 flowing through the hydrogen gas supply path L0 is supplied to the first fuel cell unit 1n via a sub-hydrogen gas supply path L0n.

[0036] 1, the third recovery path L31 may merge with the hydrogen gas supply path L0 at a junction P1, so that the hydrogen-containing gas G2 delivered from the hydrogen-containing gas supply device 40 may be supplied to the plurality of first fuel cell units 11, 12, ..., 1 n.

[0037] Although not shown, the fuel cell system 100 may include a plurality of third sub-recovery paths branching from the third recovery path L31 so as to supply the hydrogen-containing gas G2 to each of the first fuel cell units 11, 12, ..., 1n. Each of the plurality of third sub-recovery paths may be connected to the first fuel cell units 11, 12, ..., 1n. This allows the hydrogen-containing gas G2 delivered from the hydrogen-containing gas supply device 40 to be supplied to each of the first fuel cell units 11, 12, ..., 1n.

[0038] As shown in FIG. 1, the first recovery path L1 may be provided with a sensor 71 that detects the hydrogen concentration of the hydrogen-containing gas G1 flowing through the first recovery path L1.

[0039] As shown in FIG. 1, the second recovery path L2 may be provided with a sensor 72 that detects the hydrogen concentration of the hydrogen-containing gas G2 flowing through the second recovery path L2.

[0040] The hydrogen-containing gas supply device 40 pressurizes the hydrogen-containing gas G2 discharged from the recovery device 30. As a result, the hydrogen-containing gas G2 is supplied to the first fuel cell units 11, 12, ..., 1 n. In the example shown in Fig. 1, the hydrogen-containing gas supply device 40 pressure-feeds the hydrogen-containing gas G2 to the third recovery path L31. The hydrogen-containing gas G2 is supplied to the first fuel cell units 11, 12, ..., 1 n via the third recovery path L31.

[0041] The configuration of the hydrogen-containing gas supply device 40 is not particularly limited as long as it can pressurize the hydrogen-containing gas G2 discharged from the recovery device 30 so that the hydrogen-containing gas G2 can be supplied to the first fuel cell units 11, 12, ..., 1n. Examples of the hydrogen-containing gas supply device 40 include a pump, a compressor, a blower, and a fan. The hydrogen-containing gas supply device 40 is typically a pump. The pump may be a rotary pump or a reciprocating pump.

[0042] The hydrogen-containing gas G2 may be delivered from the hydrogen-containing gas supply device 40 at a predetermined timing. For example, when the hydrogen concentration of the hydrogen-containing gas G2 recovered by the recovery device 30 exceeds a threshold concentration, or when the power generated by the first fuel cell unit 11, 12, ..., 1n exceeds a threshold power, the pressurized hydrogen-containing gas G2 may be supplied to the first fuel cell unit 11, 12, ..., 1n. With this configuration, the hydrogen-containing gas G2 can be supplied to the first fuel cell unit 11, 12, ..., 1n at a timing as needed.

[0043] For example, if the hydrogen concentration of the hydrogen-containing gas G2 recovered by the recovery device 30 exceeds a threshold concentration, it may be determined that the hydrogen concentration of the hydrogen-containing gas G2 is sufficiently high, and the hydrogen-containing gas G2 may be delivered from the hydrogen-containing gas supply device 40. For example, the threshold concentration may be set to 90% or more.

[0044] The hydrogen concentration of the hydrogen-containing gas G2 is detected by a sensor 72 installed in the second recovery path L2, and if the detected hydrogen concentration exceeds a threshold concentration, it is determined that the hydrogen concentration of the hydrogen-containing gas G2 is sufficiently high, and the hydrogen-containing gas G2 may be delivered from the hydrogen-containing gas supply device 40.

[0045] For example, if the power generated by the first fuel cell unit 11, 12, ..., 1n exceeds a threshold power, the power generated may be determined to be sufficiently high, and hydrogen-containing gas G2 may be delivered from the hydrogen-containing gas supply device 40. The threshold power may be set appropriately depending on the power generation capacity of the first fuel cell unit 11, 12, ..., 1n, etc.

[0046] The power generated by the first fuel cell units 11, 12, ... 1n is detected by a power detector (not shown), and if the total detected power generation exceeds a threshold power, it is determined that the power generation is sufficiently high, and hydrogen-containing gas G2 may be sent out from the hydrogen-containing gas supply device 40.

[0047] The controller 50 may control the hydrogen-containing gas supply device 40 so that the hydrogen-containing gas G2 is delivered from the hydrogen-containing gas supply device 40 at a predetermined timing. For example, the controller 50 may control the hydrogen-containing gas supply device 40 so that pressurized hydrogen-containing gas G2 is supplied to the first fuel cell unit 11, 12, ..., 1n when the hydrogen concentration of the hydrogen-containing gas G2 recovered by the recovery device 30 exceeds a threshold concentration or when the power generated by the first fuel cell unit 11, 12, ..., 1n exceeds a threshold power.

[0048] For example, when the hydrogen concentration of the hydrogen-containing gas G2 recovered by the recovery device 30 exceeds a threshold concentration, the controller 50 may control the hydrogen-containing gas supply device 40 so that the hydrogen-containing gas G2 is delivered from the hydrogen-containing gas supply device 40. When the hydrogen-containing gas supply device 40 is a rotary pump, the controller 50 may control the hydrogen-containing gas supply device 40 as follows. First, the controller 50 receives a detection value of the hydrogen concentration of the hydrogen-containing gas G2 flowing through the second recovery path L2 from a sensor 72 provided in the second recovery path L2. When the received detection value of the sensor 72 exceeds the threshold concentration, the controller 50 increases the rotation speed of the rotary pump so that the hydrogen-containing gas G2 is delivered from the hydrogen-containing gas supply device 40 (rotary pump).

[0049] For example, when the power generated by the first fuel cell units 11, 12, ... 1n exceeds a threshold power, the controller 50 may control the hydrogen-containing gas supply device 40 so that the hydrogen-containing gas G2 is delivered from the hydrogen-containing gas supply device 40. When the hydrogen-containing gas supply device 40 is a rotary pump, the controller 50 may control the hydrogen-containing gas supply device 40 as follows: First, the controller 50 receives detected values ​​of the power generated by the first fuel cell units 11, 12, ... 1n from a power detector (not shown). When the sum of the received detected values ​​from the power detector exceeds the threshold power, the controller 50 increases the rotation speed of the rotary pump so that the hydrogen-containing gas G2 is delivered from the hydrogen-containing gas supply device 40 (rotary pump).

[0050] The controller 50 is a computer that includes, for example, a storage device that stores programs required for increasing or decreasing the rotation speed of a pump or a fan, and a processor that reads and executes the programs from the storage device.

[0051] As shown in FIG. 1 , a purge path Lp may be connected to the first recovery path L1 at a branch point P2 upstream of the sensor 71. The purge path Lp is a path for periodically discharging the nitrogen-containing hydrogen-containing gas G1 to the outside as a purge gas. A purge valve 60 is disposed in the purge path Lp. The purge valve 60 is typically an on-off valve. By periodically discharging the purge gas to the outside through the purge path Lp, the hydrogen concentration can be increased more efficiently by the concentrating section 30b of the recovery device 30.

[0052] The opening and closing of the purge valve 60 may be controlled, for example, in accordance with the on / off of the first fuel cell units 11, 12, . . . 1n or the power generated by the first fuel cell units 11, 12, .

[0053] Figure 2 is a configuration diagram showing another example of a fuel cell system according to the present embodiment. The fuel cell system 101 shown in Figure 2 further includes a second fuel cell unit 20 that is different from the multiple first fuel cell units 10. In the fuel cell system 101, a controller 50 controls a hydrogen-containing gas supply device 40 so that pressurized hydrogen-containing gas G2 is supplied to the second fuel cell unit 20. Except for these points, the fuel cell system 101 has the same configuration as the fuel cell system 100 described above. Therefore, in Figure 2, the same elements as those in the fuel cell system 100 are designated by the same reference numerals, and detailed description thereof will be omitted.

[0054] 2, unreacted hydrogen generated during electrochemical reactions in the first fuel cell units 10 can be effectively utilized in a second fuel cell unit 20, which is different from the first fuel cell units 10. This reduces fuel gas loss, improving the power generation efficiency of the fuel cell system 101.

[0055] The second fuel cell unit 20 differs from the first fuel cell units 10 in that the hydrogen-containing gas discharged from the second fuel cell unit 20 is not recovered in the recovery vessel 30. In other words, the fuel cell system 101 does not have a path for guiding the hydrogen-containing gas discharged from the second fuel cell unit 20 to the recovery vessel 30.

[0056] The second fuel cell unit 20 includes a second fuel cell stack 20a. The second fuel cell stack 20a generates electricity by receiving an anode gas and a cathode gas. The anode gas is hydrogen gas. The cathode gas is an oxygen-containing gas such as air. The second fuel cell stack 20a may have the same configuration as the first fuel cell stack 10a.

[0057] 2 , the fuel cell system 101 may include, as the third recovery path L3, a third recovery path L32 that guides the hydrogen-containing gas G2 from the hydrogen-containing gas supply device 40 to the second fuel cell unit 20. The hydrogen-containing gas G2 delivered from the hydrogen-containing gas supply device 40 may be guided to the second fuel cell unit 20 by the third recovery path L32.

[0058] Although not shown, the fuel cell system 101 may further include a hydrogen gas supply path that introduces hydrogen gas as fuel gas to the second fuel cell unit 20. Hydrogen gas discharged from an external hydrogen storage tank or the like may be introduced to the second fuel cell unit 20 by the hydrogen gas supply path. Hydrogen gas may be supplied from a common hydrogen storage tank to the multiple first fuel cell units 11, 12, ... 1n and the second fuel cell unit 20. The hydrogen gas supply path that introduces hydrogen gas as fuel gas to the second fuel cell unit 20 may be one of multiple sub-hydrogen gas supply paths branching off from the hydrogen gas supply path L0.

[0059] Although not shown, the fuel cell system 101 may be provided with an exhaust path for discharging the hydrogen-containing gas discharged from the second fuel cell unit 20 to the outside of the system.

[0060] The hydrogen-containing gas G2 may be delivered from the hydrogen-containing gas supply device 40 at a predetermined timing. For example, when the hydrogen concentration of the hydrogen-containing gas G2 recovered by the recovery device 30 exceeds a threshold concentration, or when the power generated by the first fuel cell unit 11, 12, ... 1n exceeds a threshold power, the pressurized hydrogen-containing gas G2 may be supplied to the second fuel cell unit 20. With this configuration, the hydrogen-containing gas G2 can be supplied to the second fuel cell unit 20 at a timing as needed.

[0061] For example, if the hydrogen concentration of the hydrogen-containing gas G2 recovered by the recovery device 30 exceeds a threshold concentration, it may be determined that the hydrogen concentration of the hydrogen-containing gas G2 is sufficiently high, and the hydrogen-containing gas G2 may be delivered from the hydrogen-containing gas supply device 40. For example, the threshold concentration may be set to 90% or more.

[0062] The hydrogen concentration of the hydrogen-containing gas G2 is detected by a sensor 72 installed in the second recovery path L2, and if the detected hydrogen concentration exceeds a threshold concentration, it is determined that the hydrogen concentration of the hydrogen-containing gas G2 is sufficiently high, and the hydrogen-containing gas G2 may be delivered from the hydrogen-containing gas supply device 40.

[0063] For example, if the power generated by the second fuel cell unit 20 exceeds a threshold power, the power generated may be determined to be sufficiently high, and hydrogen-containing gas G2 may be delivered from the hydrogen-containing gas supply device 40. The threshold power may be set appropriately depending on the power generation capacity of the second fuel cell unit 20, etc.

[0064] The power generated by the second fuel cell unit 20 is detected by a power detector (not shown), and if the detected power generated exceeds a threshold power, it is determined that the power generated is sufficiently high, and hydrogen-containing gas G2 may be sent out from the hydrogen-containing gas supply device 40.

[0065] The controller 50 may control the hydrogen-containing gas supply device 40 so that the hydrogen-containing gas G2 is delivered from the hydrogen-containing gas supply device 40 at a predetermined timing. For example, the controller 50 may control the hydrogen-containing gas supply device 40 so that pressurized hydrogen-containing gas G2 is supplied to the second fuel cell unit 20 when the hydrogen concentration of the hydrogen-containing gas G2 recovered by the recovery device 30 exceeds a threshold concentration, or when the power generation power of the first fuel cell unit 11, 12, ... 1n exceeds a threshold power.

[0066] For example, when the hydrogen concentration of the hydrogen-containing gas G2 recovered by the recovery device 30 exceeds a threshold concentration, the controller 50 may control the hydrogen-containing gas supply device 40 so that the hydrogen-containing gas G2 is delivered from the hydrogen-containing gas supply device 40. When the hydrogen-containing gas supply device 40 is a rotary pump, the controller 50 may control the hydrogen-containing gas supply device 40 as follows. First, the controller 50 receives a detection value of the hydrogen concentration of the hydrogen-containing gas G2 flowing through the second recovery path L2 from a sensor 72 provided in the second recovery path L2. When the received detection value of the sensor 72 exceeds the threshold concentration, the controller 50 increases the rotation speed of the rotary pump so that the hydrogen-containing gas G2 is delivered from the hydrogen-containing gas supply device 40 (rotary pump).

[0067] For example, when the power generated by the second fuel cell unit 20 exceeds a threshold power, the controller 50 may control the hydrogen-containing gas supply device 40 so that hydrogen-containing gas G2 is delivered from the hydrogen-containing gas supply device 40. When the hydrogen-containing gas supply device 40 is a rotary pump, the controller 50 may control the hydrogen-containing gas supply device 40 as follows: First, the controller 50 receives a detected value of the power generated by the second fuel cell unit 20 from a power detector (not shown). When the received detected value from the power detector exceeds the threshold power, the controller 50 increases the rotation speed of the rotary pump so that hydrogen-containing gas G2 is delivered from the hydrogen-containing gas supply device 40 (rotary pump).

[0068] 2, the fuel cell system 101 includes one second fuel cell unit 20, but the number of second fuel cell units 20 included in the fuel cell system 101 is not limited to this. The fuel cell system 101 may include multiple second fuel cell units 20. The multiple second fuel cell units 20 may be arranged in parallel with each other.

[0069] Figure 3 is a configuration diagram showing yet another example of a fuel cell system according to the present embodiment. In a fuel cell system 102 shown in Figure 3, a controller 50 controls a hydrogen-containing gas supply device 40 so that pressurized hydrogen-containing gas G2 is supplied to at least one of the plurality of first fuel cell units 10 and to the second fuel cell unit 20. Except for this, the fuel cell system 102 has the same configuration as the fuel cell system 101 described above. Therefore, in Figure 3, the same elements as those in the fuel cell system 101 are designated by the same reference numerals, and detailed description thereof will be omitted.

[0070] 3, unreacted hydrogen generated during the electrochemical reaction in the first fuel cell units 10 can be effectively utilized in both the first fuel cell units 10 and the second fuel cell unit 20. This reduces fuel gas loss, improving the power generation efficiency of the fuel cell system 102.

[0071] 3 , the fuel cell system 102 may include, as the third recovery path L3, a third recovery path L33 that guides the hydrogen-containing gas G2 from the hydrogen-containing gas supply device 40 to at least one of the first fuel cell units 11, 12, ..., 1n and the second fuel cell unit 20. The third recovery path L33 may guide the hydrogen-containing gas G2 delivered from the hydrogen-containing gas supply device 40 to at least one of the first fuel cell units 11, 12, ..., 1n and the second fuel cell unit 20. The third recovery path L33 may guide the hydrogen-containing gas G2 delivered from the hydrogen-containing gas supply device 40 to all of the first fuel cell units 11, 12, ..., 1n and the second fuel cell unit 20.

[0072] 3 , the fuel cell system 102 may include a first portion L33a branching from the third recovery path L33 to supply the hydrogen-containing gas G2 to the first fuel cell unit 11, 12, ..., 1n, and a second portion L33b branching from the third recovery path L33 to supply the hydrogen-containing gas G2 to the second fuel cell unit 20. The first portion L33a and the second portion L33b may branch from the third recovery path L33 at a branch point P3. The hydrogen-containing gas G2 delivered from the hydrogen-containing gas supply device 40 may be supplied to the first fuel cell unit 11, 12, ..., 1n by the first portion L33a. The hydrogen-containing gas G2 delivered from the hydrogen-containing gas supply device 40 may be supplied to the second fuel cell unit 20 by the second portion L33b.

[0073] A flow path switching mechanism 80 may be provided at the branch point P3. The flow path switching mechanism 80 switches the flow path between the first portion L33a and the second portion L33b. The flow path switching mechanism 80 may be a three-way valve provided at the branch point P3, or may be a two-way valve provided at each of the first portion L33a and the second portion L33b.

[0074] The flow path switching mechanism 80 may be switched at a predetermined timing. With this configuration, the pressurized hydrogen-containing gas G2 can be supplied to at least one of the plurality of first fuel cell units 10 or the second fuel cell unit 20 at a timing as needed. The predetermined timing can be the timing described above for the fuel cell system 100 and the fuel cell system 101.

[0075] The controller 50 may control the switching of the flow path switching mechanism 80 at a predetermined timing.

[0076] (Modification) FIG. 4 is a configuration diagram showing an example of a fuel cell system according to a modification of the above embodiment. In a fuel cell system 200 according to the modification, each of the plurality of first fuel cell units 10 includes a circulation path R10. In each of the plurality of first fuel cell units 10, the circulation path R10 guides the hydrogen-containing gas G1 from the anode outlet of the first fuel cell unit 10 to the anode inlet of the first fuel cell unit 10. That is, the fuel cell system 200 further includes a plurality of circulation paths R10. Except for this, the fuel cell system 200 has the same configuration as the fuel cell system 100 described above. Therefore, in FIG. 4, the same elements as those in the fuel cell system 100 are designated by the same reference numerals, and detailed description thereof will be omitted.

[0077] According to the configuration of the fuel cell system 200 shown in Figure 4, unreacted hydrogen generated during the electrochemical reaction in each of the multiple first fuel cell units 10 can be recycled and effectively utilized. Furthermore, the hydrogen-containing gas G1 that does not react even after recycling in each of the multiple first fuel cell units 10 can be effectively utilized throughout the entire system. This further reduces fuel gas loss. As a result, the power generation efficiency of the fuel cell system 200 is further improved.

[0078] In the example shown in FIG. 4, the fuel cell system 200 includes circulation routes R11, R12, . . . R1n as the plurality of circulation routes R10.

[0079] In the example shown in Fig. 4, the first fuel cell unit 11 includes a circulation path R11. The circulation path R11 guides the hydrogen-containing gas G1 discharged from the anode outlet of the first fuel cell unit 11 to the anode inlet of the first fuel cell unit 11. The first fuel cell unit 12 includes a circulation path R12. The circulation path R12 guides the hydrogen-containing gas G1 discharged from the anode outlet of the first fuel cell unit 12 to the anode inlet of the first fuel cell unit 12. The first fuel cell unit 1n includes a circulation path R1n. The circulation path R1n guides the hydrogen-containing gas G1 discharged from the anode outlet of the first fuel cell unit 1n to the anode inlet of the first fuel cell unit 1n.

[0080] As shown in FIG. 4 , in the first fuel cell unit 11, the circulation path R11 may branch from the first sub-recovery path L11 and merge with the sub-hydrogen gas supply path L01. The hydrogen-containing gas G1 discharged from the anode outlet of the first fuel cell unit 11 may pass through the circulation path R11 and merge with the sub-hydrogen gas supply path L01. As a result, the hydrogen-containing gas G1 may be supplied to the anode inlet of the first fuel cell unit 11. In the first fuel cell unit 12, the circulation path R12 may branch from the first sub-recovery path L12 and merge with the sub-hydrogen gas supply path L02. The hydrogen-containing gas G1 discharged from the anode outlet of the first fuel cell unit 12 may pass through the circulation path R12 and merge with the sub-hydrogen gas supply path L02. As a result, the hydrogen-containing gas G1 may be supplied to the anode inlet of the first fuel cell unit 12. In the first fuel cell unit 1n, the circulation path R1n may branch off from the first sub-recovery path L1n and merge with the sub-hydrogen gas supply path L0n. The hydrogen-containing gas G1 discharged from the anode outlet of the first fuel cell unit 1n may merge with the sub-hydrogen gas supply path L0n via the circulation path R1n. This allows the hydrogen-containing gas G1 to be supplied to the anode inlet of the first fuel cell unit 1n.

[0081] As shown in FIG. 4, each of the circulation routes R10 may be provided with a sensor 10c for detecting the hydrogen concentration of the hydrogen-containing gas G1 flowing through the circulation route R10.

[0082] Each of the plurality of first fuel cell units 10 may further include a flow path switching mechanism 10b. In each of the plurality of first fuel cell units 10, the circulation path R10 may be connected to the first recovery path L1 via the flow path switching mechanism 10b. With this configuration, in each of the plurality of first fuel cell units 10, the flow path can be switched between the first recovery path L1 and the circulation path R10 at a predetermined timing. Therefore, for example, it is possible to prevent excessive discharge of the hydrogen-containing gas G1 from each of the plurality of first fuel cell units 10.

[0083] The flow path switching mechanism 10b may be a three-way valve provided at the connection point between the circulation path R10 and the first recovery path L1, or may be a two-way valve provided in each of the circulation path R10 and the first recovery path L1, or may be a two-way valve provided in the first recovery path L1.

[0084] 4, in the first fuel cell unit 11, the circulation path R10 may be connected to the first sub-recovery path L11 via a flow path switching mechanism 10b. In the first fuel cell unit 12, the circulation path R10 may be connected to the first sub-recovery path L12 via a flow path switching mechanism 10b. In the first fuel cell unit In, the circulation path R10 may be connected to the first sub-recovery path L1n via a flow path switching mechanism 10b.

[0085] For example, when the generated power of multiple first fuel cell units 10 exceeds a threshold power, the flow path switching mechanism 10b may be controlled in each of the multiple first fuel cell units 10 so that hydrogen-containing gas G1 is supplied to the circulation path R10.

[0086] For example, if the power generated by the plurality of first fuel cell units 10 exceeds a threshold power, it may be determined that the power generated is sufficiently high, and each flow path switching mechanism 10b may be switched to the first recovery path L1 to recover the hydrogen-containing gas G1 in the recovery device 30. The threshold power may be set as appropriate depending on the power generation capacity of the plurality of first fuel cell units 10, etc.

[0087] The power generated by the multiple first fuel cell units 10 is detected by a power detector (not shown), and if the total of the detected power generated exceeds a threshold power, it is determined that the power generated is sufficiently high, and each flow path switching mechanism 10b is switched to the first recovery path L1 to recover the hydrogen-containing gas G1 in the recovery device 30.

[0088] For example, each flow path switching mechanism 10b may be switched to the first recovery path L1 only when the purge valve 60 is open, and the hydrogen-containing gas G1 may be recovered in the recovery device 30.

[0089] For example, in each of the multiple first fuel cell units 10, if the hydrogen concentration of the hydrogen-containing gas G1 flowing through the circulation route R10 exceeds a threshold concentration, it may be determined that the hydrogen concentration of the hydrogen-containing gas G1 is sufficiently high, and the flow path switching mechanism 10b may be switched to the first recovery route L1 to recover the hydrogen-containing gas G1 in the recovery device 30. For example, the threshold concentration may be set to 90% or higher.

[0090] In each of the multiple first fuel cell units 10, the hydrogen concentration of the hydrogen-containing gas G1 is detected by a sensor 10c provided in the circulation route R10, and if the detected hydrogen concentration exceeds a threshold concentration, it is determined that the hydrogen concentration of the hydrogen-containing gas G1 is sufficiently high, and the flow path switching mechanism 10b is switched to the first recovery route L1 to recover the hydrogen-containing gas G1 in the recovery device 30.

[0091] The controller 50 may control each flow path switching mechanism 10b.

[0092] For example, when the power generation of the plurality of first fuel cell units 10 exceeds a threshold power, the controller 50 may control the flow path switching mechanism 10b in each of the plurality of first fuel cell units 10 so that the hydrogen-containing gas G1 is supplied to the circulation path R10. The controller 50 may control the flow path switching mechanism 10b as follows: First, the controller 50 receives a detection value of the hydrogen concentration of the hydrogen-containing gas G1 flowing through the circulation path R10 from a sensor 10c provided in the circulation path R10. When the received detection value from the sensor 10c exceeds the threshold concentration, the controller 50 switches each flow path switching mechanism 10b to the first recovery path L1 so that the hydrogen-containing gas G1 is recovered in the recovery device 30.

[0093] For example, when the power generation of the plurality of first fuel cell units 10 exceeds a threshold power, the controller 50 may control the flow path switching mechanism 10b in each of the plurality of first fuel cell units 10 so that the hydrogen-containing gas G1 is recovered in the recovery device 30. The controller 50 may control the flow path switching mechanism 10b as follows: First, the controller 50 receives detection values ​​of the power generation of the plurality of first fuel cell units 10 from a power detector (not shown). When the sum of the received detection values ​​of the power detectors exceeds the threshold power, the controller 50 switches each flow path switching mechanism 10b to the first recovery path L1 so that the hydrogen-containing gas G1 is recovered in the recovery device 30.

[0094] [1-2. Operation] The operation and function of the fuel cell systems 100, 101, 102, and 200 according to the present embodiment configured as described above will be described below with reference to FIGS.

[0095] 1, in each of the first fuel cell stacks 10a of the first fuel cell units 11, 12, ... 1n, DC power is generated by an electrochemical reaction between hydrogen gas G0 as the anode gas and an oxygen-containing gas as the cathode gas. The generated DC power is converted to AC power by a power converter (not shown) and supplied to a load (not shown).

[0096] 1, a hydrogen-containing gas G1 is discharged from each of the first fuel cell units 11, 12, ..., 1n during operation. The hydrogen-containing gas G1 is an anode off-gas produced by the electrochemical reaction in the first fuel cell stack 10a.

[0097] The hydrogen-containing gas G1 discharged from each of the first fuel cell units 11, 12, ... 1n passes through the first recovery path L1 and is stored in the tank 30a of the recovery device 30. The nitrogen concentration in the hydrogen-containing gas G1 stored in the tank 30a is reduced by the concentration section 30b, thereby obtaining a hydrogen-containing gas G2 with a high hydrogen concentration.

[0098] The hydrogen-containing gas G2 recovered by the recovery device 30 is supplied to the hydrogen-containing gas supply device 40 via the second recovery path L2, and is pressurized by the hydrogen-containing gas supply device 40. As a result, the hydrogen-containing gas G2 is pressure-fed to the third recovery path L31 by the hydrogen-containing gas supply device 40. The hydrogen-containing gas G2 is supplied to at least one of the first fuel cell units 11, 12, ... 1n via the third recovery path L31.

[0099] The timing of delivery of the hydrogen-containing gas G2 from the hydrogen-containing gas supply device 40 may be controlled by the controller 50.

[0100] During operation of the first fuel cell units 11, 12, . . . 1n, the hydrogen-containing gas G1 may be periodically discharged to the outside as a purge gas using the purge path Lp.

[0101] In the fuel cell system 101 shown in FIG. 2, the hydrogen-containing gas G2 pressure-fed to the third recovery line L32 by the hydrogen-containing gas supply device 40 is supplied to the second fuel cell unit 20 via the third recovery line L32.

[0102] The timing of delivery of the hydrogen-containing gas G2 from the hydrogen-containing gas supply device 40 may be controlled by the controller 50.

[0103] In the fuel cell system 102 shown in Figure 3, the hydrogen-containing gas G2 pressurized by the hydrogen-containing gas supply device 40 into the third recovery path L33 is supplied to at least one of the multiple first fuel cell units 11, 12, ... 1n via the first part L33a of the third recovery path L33, and is also supplied to the second fuel cell unit 20 via the second part L33b of the third recovery path L33.

[0104] The timing of delivery of the hydrogen-containing gas G2 from the hydrogen-containing gas supply device 40 may be controlled by the controller 50.

[0105] By switching the flow path switching mechanism 80 at a predetermined timing, the pressurized hydrogen-containing gas G2 may be supplied to the plurality of first fuel cell units 10 or the second fuel cell units 20. The switching of the flow path switching mechanism 80 may be controlled by the controller 50.

[0106] (Modification) In a fuel cell system 200 according to a modification shown in FIG. 4 , in each of the first fuel cell units 11, 12, ..., 1n, the hydrogen-containing gas G1 discharged from the first fuel cell stack 10a is recycled via a circulation path R10. Furthermore, the hydrogen-containing gas G1 that has not reacted even after recycling in each of the first fuel cell units 11, 12, ..., 1n is stored in the tank 30a of the recovery device 30 via a first recovery path L1. The nitrogen concentration of the hydrogen-containing gas G1 stored in the tank 30a is reduced by the concentrating section 30b. The hydrogen-containing gas G2 discharged from the recovery device 30 is supplied to the hydrogen-containing gas supply device 40 via a second recovery path L2 and is pressurized. As a result, the hydrogen-containing gas G2 is pressure-fed to the third recovery path L31 by the hydrogen-containing gas supply device 40. The hydrogen-containing gas G2 is supplied to at least one of the first fuel cell units 11, 12, ..., 1n via the third recovery path L31.

[0107] The timing of delivery of the hydrogen-containing gas G2 from the hydrogen-containing gas supply device 40 may be controlled by the controller 50.

[0108] In each of the first fuel cell units 11, 12, ..., 1n, the flow path may be switched between the first recovery path L1 and the circulation path R10 by switching the flow path switching mechanism 10b at a predetermined timing. The switching of each flow path switching mechanism 10b may be controlled by the controller 50.

[0109] [1-3. Effects, etc.] As described above, in this embodiment, the fuel cell system includes a plurality of first fuel cell units 10, a recovery device 30 that recovers hydrogen-containing gas G1 discharged from each of the plurality of first fuel cell units 10, a hydrogen-containing gas supply device 40 that pressurizes the hydrogen-containing gas G2 recovered by the recovery device 30, and a controller 50 that controls the hydrogen-containing gas supply device 40 so that the pressurized hydrogen-containing gas G2 is supplied to at least one selected from the group consisting of at least one of the plurality of first fuel cell units 10 and at least one second fuel cell unit 20 different from the plurality of first fuel cell units 10.

[0110] This allows for effective use of unreacted hydrogen generated during the electrochemical reactions in the multiple first fuel cell units 10, reducing fuel gas loss and improving the power generation efficiency of the fuel cell system.

[0111] In addition, in this embodiment, the controller 50 may control the hydrogen-containing gas supply device 40 so that pressurized hydrogen-containing gas G2 is supplied to at least one selected from the group consisting of the plurality of first fuel cell units 10 and second fuel cell units 20 when the hydrogen concentration of the hydrogen-containing gas G2 recovered by the recovery device 30 exceeds a threshold concentration, or when the power generated by the plurality of first fuel cell units exceeds a threshold power.

[0112] This makes it possible to improve the power generation efficiency of the fuel cell system.

[0113] In this embodiment, the recovery vessel 30 may include a concentration section 30b that increases the hydrogen concentration in the hydrogen-containing gas G1.

[0114] This allows the concentrator 30b to increase the hydrogen concentration even if the hydrogen concentration of the hydrogen-containing gas G1 discharged from each of the first fuel cell units 10 is low. As a result, the hydrogen-containing gas G2 with a high hydrogen concentration can be supplied to the first fuel cell units 10, further improving the power generation efficiency of the fuel cell system.

[0115] In this embodiment, the concentrating unit 30b may increase the hydrogen concentration by reducing the nitrogen concentration in the hydrogen-containing gas G1.

[0116] This allows the concentration of hydrogen to be easily increased by the concentrating section 30b.

[0117] In addition, in this embodiment, the fuel cell system may further include a first recovery path L1 that guides the hydrogen-containing gas G1 discharged from each of the multiple first fuel cell units 10 to the recovery device 30, a second recovery path that guides the hydrogen-containing gas G2 from the recovery device 30 to the hydrogen-containing gas supply device 40, and a third recovery path that guides the hydrogen-containing gas G2 from the hydrogen-containing gas supply device 40 to at least one of the multiple first fuel cell units 10 and at least one selected from the group consisting of the second fuel cell units 20.

[0118] This allows unreacted hydrogen generated during the electrochemical reaction in the plurality of first fuel cell units 10 to be smoothly transported and effectively utilized.

[0119] In addition, in this embodiment, in the fuel cell system, each of the multiple first fuel cell units 10 includes a circulation path R10 that guides the hydrogen-containing gas G1 from the anode outlet of the first fuel cell unit 10 to the anode inlet of the first fuel cell unit 10.

[0120] This allows for the recycling and effective use of unreacted hydrogen produced during the electrochemical reaction in each of the first fuel cell units 10. Furthermore, the hydrogen-containing gas G1 that does not react even after recycling in each of the first fuel cell units 10 can be effectively used throughout the entire system.

[0121] In addition, this embodiment further includes a first recovery path L1 that guides the hydrogen-containing gas G1 discharged from each of the multiple first fuel cell units 10 to the recovery vessel 30, and each of the multiple first fuel cell units 10 further includes a flow path switching mechanism 10b, and in each of the multiple first fuel cell units 10, the circulation path R10 may be connected to the first recovery path L1 via the flow path switching mechanism 10b.

[0122] This allows the flow path to be switched between the first recovery path L1 and the circulation path R10 at a predetermined timing in each of the multiple first fuel cell units 10. Therefore, for example, it is possible to prevent excessive discharge of the hydrogen-containing gas G1 from each of the multiple first fuel cell units 10.

[0123] In addition, in this embodiment, when the generated power of the multiple first fuel cell units 10 exceeds a threshold power, the controller 50 may control the flow path switching mechanism 10b so that hydrogen-containing gas G1 is supplied to the circulation path R10 in each of the multiple first fuel cell units 10.

[0124] This makes it possible to prevent, for example, the hydrogen-containing gas G1 from being excessively discharged from each of the first fuel cell units 10 .

[0125] (Other Embodiments) As described above, the embodiments have been described as examples of the technology disclosed in this application. However, the technology in this disclosure is not limited to these, and can be applied to embodiments in which modifications, substitutions, additions, omissions, etc. are made. Furthermore, it is also possible to combine the components described in the above embodiments to create new embodiments.

[0126] For example, by combining the modified example (FIG. 4) with the example shown in FIG. 2, the hydrogen-containing gas G1 that has not reacted even when recycled in each of the multiple first fuel cell units 10 may be effectively utilized in a second fuel cell unit 20 that is different from the multiple first fuel cell units 10. For example, by combining the modified example (FIG. 4) with the example shown in FIG. 3, the hydrogen-containing gas G1 that has not reacted even when recycled in each of the multiple first fuel cell units 10 may be effectively utilized in both the multiple first fuel cell units 10 and the second fuel cell unit 20.

[0127] Each of the first recovery path L1, the second recovery path L2, the third recovery path L3, etc. can be configured by one or more pipes.

[0128] The technology disclosed herein is applicable to, for example, a system that supplies power by linking a solar power generation device, a fuel cell, and a storage battery. The technology disclosed herein is applicable to, for example, environmental protection initiatives such as RE100 (Renewable Energy 100%).

Claims

1. Multiple first fuel cell units, A recovery device for recovering hydrogen-containing gas discharged from each of the plurality of first fuel cell units, A hydrogen-containing gas supply unit pressurizes the hydrogen-containing gas recovered by the recovery unit, A controller that controls the hydrogen-containing gas supplyer so that the pressurized hydrogen-containing gas is supplied to at least one of the plurality of first fuel cell units and at least one selected from the group consisting of a second fuel cell unit different from the plurality of first fuel cell units, Equipped with, The recovery device is a fuel cell system that includes a concentration unit for increasing the hydrogen concentration in the hydrogen-containing gas.

2. The controller controls the hydrogen-containing gas supplyer so that the pressurized hydrogen-containing gas is supplied to at least one selected from the group consisting of the plurality of first fuel cell units and the second fuel cell unit when the hydrogen concentration of the hydrogen-containing gas recovered by the recovery device exceeds a threshold concentration, or when the power generated by the plurality of first fuel cell units exceeds a threshold power. The fuel cell system according to claim 1.

3. The concentration unit increases the hydrogen concentration by reducing the nitrogen concentration in the hydrogen-containing gas. The fuel cell system according to claim 1.

4. A first recovery path that guides the hydrogen-containing gas discharged from each of the plurality of first fuel cell units to the recovery device, A second recovery path that guides the hydrogen-containing gas from the recovery device to the hydrogen-containing gas supply device, A third recovery path that guides the hydrogen-containing gas from the hydrogen-containing gas supplyer to at least one selected from the group consisting of at least one of the plurality of first fuel cell units and the second fuel cell unit, Furthermore, The fuel cell system according to claim 1.

5. Each of the plurality of first fuel cell units includes a circulation path that guides the hydrogen-containing gas from the anode outlet of the first fuel cell unit to the anode inlet of the first fuel cell unit. The fuel cell system according to claim 1.

6. The system further comprises a first recovery path that guides the hydrogen-containing gas discharged from each of the plurality of first fuel cell units to the recovery device. Each of the plurality of first fuel cell units further includes a flow path switching mechanism, In each of the plurality of first fuel cell units, the circulation path is connected to the first recovery path via the flow path switching mechanism. The fuel cell system according to claim 5.

7. The controller controls the flow path switching mechanism in each of the plurality of first fuel cell units so that the hydrogen-containing gas is supplied to the circulation path when the power generated by the plurality of first fuel cell units exceeds a threshold power. The fuel cell system according to claim 6.