JP2020087708A - Fuel cell system - Google Patents

Abstract

To provide a fuel cell system capable of reducing pressure loss of anode gas while restraining fuel shortage.SOLUTION: A fuel cell system 10 includes a fuel cell stack 20, a first manifold 22, a second manifold 23 and branch flow paths W21, W22. The first manifold 22 is connected, respectively, with one ends of multiple cells 21. The second manifold 23 is connected, respectively, with the other ends of the multiple cells, and has independent first internal flow path 231 and second internal flow paths 232, 233. The cell 21 includes a central part cell 211 where anode gas flows from the first manifold 22 toward the second manifold 23, and end cells 212, 213 where the anode gas flows from the second manifold 23 toward the first manifold 22.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to fuel cell systems.

The fuel cell stack is formed by stacking a plurality of cells. In such a fuel cell stack, the temperature of the cells arranged at the ends tends to be lower than the temperature of the cells arranged in the center. Therefore, in the cells arranged at the ends, water vapor generated by the cell reaction between the anode gas and the cathode gas is easily condensed. When water droplets are generated in the anode gas flow passage formed inside the cell due to the condensation of water vapor, the cross-sectional area of the flow passage becomes narrower, so the supply amount of anode gas in the cell decreases, so-called fuel deficiency. May be caused. Such fuel deficiency is a factor that causes a decrease in power generation of the cell and deterioration of the catalyst. As a fuel cell stack capable of eliminating such fuel deficiency, there is a fuel cell stack described in Patent Document 1 below.

In the fuel cell stack described in Patent Document 1, the anode gas introduced from the gas inlet flows through two end cells arranged at both ends of the fuel cell stack, and then is arranged in the center of the fuel cell stack. It is designed to flow through a plurality of central cells. In the battery stack, water vapor generated by the battery reaction in each cell flows downstream in the flow path of the anode gas. Therefore, the amount of water vapor increases toward the downstream side in the flow direction of the anode gas. As in the fuel cell stack described in Patent Document 1, if the central cell is arranged downstream of the end cells in the flow direction of the anode gas, the amount of water vapor present in the central cell is more than Less water vapor is present in the end cells. As a result, even if the temperature of the end cells is lowered, water droplets are less likely to be generated in the end cells, so that the fuel starvation described above can be easily avoided.

JP, 2003-157887, A

By the way, in the fuel cell stack described in Patent Document 1, since the total flow rate of the anode gas supplied to the plurality of central cells arranged in parallel flows to the two end cells, the anode gas is discharged to the end cells. When flowing through the cell, the pressure loss acting on the anode gas tends to increase. If the pressure loss of the anode gas becomes large, it is required to increase the output of the pump that pressure-feeds the anode gas to the fuel cell stack, which leads to an increase in the size of the pump, which is not preferable.

The present disclosure has been made in view of such circumstances, and an object thereof is to provide a fuel cell system capable of reducing pressure loss of anode gas while suppressing fuel deficiency.

A fuel cell system that solves the above-mentioned problems is a fuel cell stack (20), a first manifold (22), a second manifold (23), a fuel supply unit (30), and branch channels (W21, W22). And The fuel cell stack is composed of a laminated structure of a plurality of cells (21) that generate electric energy by reacting an anode gas and a cathode gas. The first manifold is connected to one end of each of the plurality of cells. The second manifold is connected to the other end of each of the plurality of cells and has an independent first internal flow path (231) and second internal flow paths (232, 233). The fuel supply unit supplies the anode gas to the first manifold through the supply flow path (W1). The branch channel guides a part of the anode gas flowing through the supply channel to the second internal channel of the second manifold. A first cell in which one end is connected to the first manifold and the other end is connected to the first internal flow path of the second manifold, and the anode gas flows in a direction from the first manifold to the second manifold (211), one end is connected to the first manifold and the other end is connected to the second internal flow path of the second manifold, and the second anode gas flows in the direction from the second manifold to the first manifold. Cells (212, 213) are included.

According to this configuration, since the anode gas is supplied from the fuel supply unit to the second cell through the branch flow path, the anode gas containing almost no water vapor is supplied to the second cell. As a result, even if the temperature of the second cell tends to be lower than that of the first cell, water droplets are less likely to be generated in the second cell, and thus fuel deficiency in the second cell can be suppressed. ..

Further, according to the above configuration, not only the anode gas flows into the first manifold from the second cell, but also the anode gas flows from the fuel supply unit through the supply passage. That is, as the flow path configuration of the anode gas, the second cell and the supply flow path are connected in parallel to the first manifold. As a result, the pressure loss of the anode gas can be reduced as compared with the case where only the second cell is connected in series to the first manifold.

The above-mentioned means and the reference numerals in parentheses in the claims are an example showing the correspondence with the specific means described in the embodiments described later.

According to the present disclosure, it is possible to provide a fuel cell system capable of reducing pressure loss of anode gas while suppressing fuel deficiency.

FIG. 1 is a block diagram showing a schematic configuration of the fuel cell system of the first embodiment. FIG. 2 is a sectional view showing the sectional structure of the cell of the first embodiment. FIG. 3 is a block diagram showing a schematic configuration of a fuel cell system of a comparative example. FIG. 4 is a block diagram showing a schematic configuration of the fuel cell system of the second embodiment. FIG. 5 is a block diagram showing an operation example of the fuel cell system of the second embodiment.

Hereinafter, an embodiment of a fuel cell system will be described with reference to the drawings. In order to facilitate understanding of the description, the same reference numerals are given to the same constituent elements in each drawing as much as possible, and overlapping description will be omitted.
<First Embodiment>
First, a first embodiment of the fuel cell system 10 shown in FIG. 1 will be described. As shown in FIG. 1, the fuel cell system 10 of this embodiment includes a fuel cell stack 20, a fuel supply unit 30, and a pump 40.

The fuel cell stack 20 is composed of a plurality of cells 21 stacked and arranged in the direction indicated by the arrow X. Each cell 21 produces electric energy by the chemical reaction between the anode gas and the cathode gas. For example, hydrogen is used as the anode gas. For example, air is used as the cathode gas. Each cell 21 is formed to extend in the direction indicated by arrow Y. Hereinafter, for convenience, the direction indicated by the arrow X is also referred to as “cell stacking direction X”. The direction indicated by arrow Y is also referred to as "cell longitudinal direction Y".

As shown in FIG. 2, the cell 21 includes a cell structure 110, an anode separator 116, and a cathode separator 117. An anode gas flow path Wa through which the anode gas flows is formed between the cell structure 110 and the anode separator 116. A cathode gas flow path Wc through which the cathode gas flows is formed between the cell structure 110 and the cathode separator 117.

The cell structure 110 has a structure in which an electrolyte membrane 111 is sandwiched between an anode catalyst layer 112 and a cathode catalyst layer 113. In the cathode catalyst layer 113, oxygen in the cathode gas flowing through the cathode gas flow passage Wc is reduced. That is, the cathode catalyst layer 113 has a function as a portion that reduces oxygen. The electrolyte membrane 111 has a function as a portion for moving oxygen ions generated by the reduction of oxygen in the cathode catalyst layer 113 to the anode catalyst layer 112. In the anode catalyst layer 112, water is generated by a chemical reaction between oxygen ions moving from the cathode catalyst layer 113 via the electrolyte membrane 111 and the anode gas flowing through the anode gas flow path Wa. That is, the anode catalyst layer 112 has a function as a portion that oxidizes the anode gas. Electric power is generated in the cell structure 110 by the electrons emitted during the chemical reaction in the anode catalyst layer 112.

The cell structure 110 further includes an anode diffusion layer 114 arranged between the anode catalyst layer 112 and the anode separator 116, and a cathode diffusion layer 115 arranged between the cathode catalyst layer 113 and the cathode separator 117. .. The anode diffusion layer 114 and the cathode diffusion layer 115 are made of a porous material. The anode diffusion layer 114 has a function of diffusing and supplying the anode gas flowing through the anode gas flow path Wa to the anode catalyst layer 112. The cathode diffusion layer 115 has a function of diffusing the cathode gas flowing through the cathode gas flow path Wc into the cathode catalyst layer 113 and supplying it.

The anode separator 116 is made of a member having irregularities on its surface. An anode gas flow path Wa is formed by the gap formed between the uneven portion of the anode separator 116 and the cell structure 110. Similarly, the cathode separator 117 is also made of a member having irregularities on its surface. A cathode gas flow path Wc is formed by a gap formed between the concavo-convex portion of the cathode separator 117 and the cell structure 110.

The fuel cell stack 20 is configured by electrically connecting cells 21 as shown in FIG. 2 in series. As shown in FIG. 1, the electric energy generated in the fuel cell stack 20 is supplied to the load 50. The load 50 can be driven by using the electric energy supplied from the fuel cell stack 20.

As shown in FIG. 1, a first manifold 22 is provided at one end of the fuel cell stack 20. One end of each of the plurality of cells 21 is connected to the first manifold 22. A second manifold 23 is provided at the other end of the fuel cell stack 20. The other end of each of the plurality of cells 21 is connected to the second manifold 23. Each of the manifolds 22 and 23 functions as a portion that distributes the anode gas to each cell 21, or a portion that collects the anode gas that has flowed through each cell 21.

A partition wall 230 is provided inside the second manifold 23. Due to the partition wall 230, inside the second manifold 23, a central part internal flow path 231 arranged at the central part of the second manifold 23 and a right end internal flow path 232 arranged at the right end part of the second manifold 23. And a left end internal flow path 233 arranged at the left end of the second manifold 23 are formed by being partitioned. Each of the internal flow channels 231 to 233 is an independent flow channel. In the present embodiment, the central internal flow passage 231 corresponds to the first internal flow passage, and the end internal flow passages 232 and 233 correspond to the second internal flow passage.

Hereinafter, for convenience, the plurality of cells 211 connected to the central internal flow passage 231 of the second manifold 23 among the plurality of cells 21 will be referred to as “central cell 211”. The plurality of cells 212 connected to the right end internal flow path 232 of the second manifold 23 are referred to as “right end cells 212”. Further, the plurality of cells 213 connected to the left end internal flow path 233 of the second manifold 23 are referred to as "left end cell 213". In the present embodiment, the central cell 211 corresponds to the first cell, and the end cells 212 and 213 correspond to the second cell.

The fuel supply unit 30 includes a tank, a regulator, and the like, and supplies the anode gas to the first manifold 22 through the supply flow path W1. In the supply passage W1, a shut valve 60, a pressure regulating valve 61, and a fuel circulation unit 70 are sequentially provided from the fuel supply unit 30 toward the first manifold 22. The supply flow path W1 is provided with a first branch flow path W21 and a second branch flow path W22 that branch from a portion between the shut valve 60 and the pressure regulating valve 61. The first branch flow passage W21 is connected to the right end internal flow passage 232 of the second manifold 23. The second branch flow passage W22 is connected to the left end internal flow passage 233 of the second manifold 23. Therefore, a part of the anode gas flowing through the supply flow path W1 is guided to the right end internal flow path 232 and the left end internal flow path 233 of the second manifold 23 through the first branch flow path W21 and the second branch flow path W22. It is like this.

The shut valve 60 is used to open and close the supply flow path W1. When the shutoff valve 60 is open, the anode gas is being supplied from the fuel supply unit 30 to the cells 21 via the manifolds 22 and 23. Therefore, the fuel cell stack 20 can generate electricity. On the other hand, when the shut valve 60 is closed, the supply of the anode gas from the fuel supply unit 30 to the cells 21 via the manifolds 22 and 23 is cut off. Therefore, the fuel cell stack 20 cannot generate power. As described above, by operating the shut valve 60, it is possible to switch between driving and stopping the fuel cell stack 20.

The pressure control valve 61 is used when adjusting the pressure of the fuel supplied from the fuel supply unit 30 to the first manifold 22.
The fuel circulation unit 70 is connected to the central internal flow passage 231 of the second manifold 23 through the circulation flow passage W4. The fuel circulation unit 70 circulates the anode exhaust gas collected in the central internal flow passage 231 of the second manifold 23 and discharged to the supply flow passage W1. As the fuel circulation unit 70, for example, an ejector is used. The anode exhaust gas contains unreacted anode gas discharged from the fuel cell stack 20. The fuel circulation unit 70 recycles the unreacted anode gas to the fuel cell stack 20 through the supply flow path W1 to improve fuel efficiency.

A discharge flow path W5 is connected in the middle of the circulation flow path W4. The discharge flow path W5 is a flow path for discharging the anode exhaust gas and water produced by the chemical reaction between the anode gas and the cathode gas to the outside. The discharge flow path W5 is provided with a discharge valve 62 for opening and closing the flow path.

A check valve 63 and an on-off valve 64 are provided in the middle of the first branch flow passage W21. The check valve 63 prevents the anode gas from flowing back from the first branch flow passage W21 to the supply flow passage W1. The on-off valve 64 is arranged downstream of the check valve 63 in the flow direction of the anode gas. The on-off valve 64 opens and closes the first branch flow passage W21 intermittently. An injector, for example, is used as the opening/closing valve 64. When the on-off valve 64 is closed, the anode gas flowing through the first branch flow passage W21 temporarily accumulates between the on-off valve 64 and the check valve 63, so that the pressure of the anode gas is increased. After that, by opening and closing the open/close valve 64, it is possible to supply the anode gas whose pressure has been increased to the right end internal flow path 232 of the second manifold 23.

A check valve 65 and an on-off valve 66 are provided in the middle of the second branch flow passage W22, as in the first branch flow passage W21.
The pump 40 supplies the cathode gas to one end of each cell 21 through the supply flow path W6. The cathode gas flowing through each cell 21 is discharged from the other end of each cell 21 through the discharge flow path W7. A pressure adjusting valve 41 for adjusting the pressure of the cathode gas is provided in the discharge passage W7.

Next, an operation example of the fuel cell system 10 of this embodiment will be described.
In the fuel cell system 10 of the present embodiment, the anode gas flows as shown by the dashed line arrow in FIG. That is, in the fuel cell system 10 of the present embodiment, the anode gas is supplied from the fuel supply unit 30 to the first manifold 22 through the supply passage W1. Further, a part of the anode gas flowing through the supply flow path W1 flows into the respective branch flow paths W21 and W22. The anode gas flowing into the first branch flow passage W21 is supplied to the right end internal flow passage 232 of the second manifold 23 after the pressure is increased in the open/close valve 64 which is opened and closed intermittently. When the pressure of the anode gas in the right end internal flow path 232 of the second manifold 23 is “Pin” and the pressure of the anode gas in the first manifold 22 is “Pout”, the opening/closing valve 64 has “Pin>Pout”. The pressure of the anode gas is increased so that As a result, in the right end cell 212, the anode gas is allowed to flow in the direction indicated by the dashed-dotted line arrow in FIG. 1, that is, in the direction from the right end internal flow path 232 of the second manifold 23 toward the first manifold 22. ing. Similarly, the anode gas flowing into the second branch flow passage W22 is also supplied to the left end internal flow passage 233 of the second manifold 23 after the pressure is increased in the open/close valve 66 which is opened and closed intermittently. As a result, in the left end cell 213, the anode gas is allowed to flow in the direction indicated by the dashed line arrow in FIG. 1, that is, in the direction from the left end internal flow path 233 of the second manifold 23 toward the first manifold 22. ing.

In the right end cell 212 of the second manifold 23, power generation is performed based on the anode gas supplied from the right end internal flow path 232 of the second manifold 23. Similarly, in the left end cell 213, power generation is performed based on the anode gas supplied from the left end internal flow path 233 of the second manifold 23.

In the first manifold 22 of the present embodiment, as shown by the dashed line arrow in FIG. 1, the anode gas directly flows from the fuel supply unit 30 through the supply flow path W1, and the right end cell 212 and the left end cell The anode gas that has once flowed through each of 213 flows in. The anode gas flowing into the first manifold 22 flows through the central cell 211, and then flows into the central internal flow passage 231 of the second manifold 23. That is, in the central cell 211, the anode gas flows in the direction from the first manifold 22 to the second manifold 23. All the anode gas flowing from the fuel supply unit 30 into the first manifold 22 through the supply flow path W1 flows through the central cell 211. In the central cell 211, the anode gas supplied from the first manifold 22 generates power.

The anode exhaust gas discharged after being used for power generation in the central cell 211 is collected in the central internal flow path 231 of the second manifold 23. The anode exhaust gas collected in the central internal flow path 231 of the second manifold 23 contains water generated by the chemical reaction of the anode gas and the cathode gas in each cell 21. Most of the water contained in the anode exhaust gas is in the state of water vapor.

The anode exhaust gas that has flowed into the central internal flow passage 231 of the second manifold 23 flows into the circulation flow passage W4. The anode exhaust gas flowing into the circulation flow passage W4 is circulated to the supply flow passage W1 through the fuel circulation portion 70 or is discharged to the outside through the discharge flow passage W5.
According to the fuel cell system 10 of the present embodiment described above, the actions and effects shown in the following (1) to (5) can be obtained.

(1) In the fuel cell system 10 of the present embodiment, the anode gas is supplied from the fuel supply unit 30 to the end cells 212 and 213 through the branch flow passages W21 and W22, respectively. It is supplied to the end cells 212 and 213. As a result, even in the case where the end cells 212 and 213 are likely to have a lower temperature than the central cell 211. Since water droplets are less likely to be generated in the anode gas flow paths Wa of the end cells 212, 213, fuel starvation in the end cells 212, 213 can be suppressed.

(2) As shown in FIG. 3, when the central cell 211 is connected in series only to the end cells 212 and 213 via the first manifold 22, it is necessary to flow to the central cell 211. All of the anode gas will flow to the end cells 212, 213. In the case of such a configuration, the pressure loss of the anode gas flowing through the end cells 212 and 213 may be very large. Specifically, the pressure loss of the fluid is proportional to the square of the flow rate. Therefore, for example, the pressure loss (Pin-Pout) in the right end cell 212 is proportional to the square of the flow rate of the anode gas flowing therein.

In this respect, in the fuel cell system 10 of the present embodiment, as shown in FIG. 1, not only the anode gas flows into the first manifold 22 from the end cells 212 and 213 but also the supply flow from the fuel supply unit 30. The anode gas is flowing in through the passage W1. That is, the anode gas flow channel configuration is such that the end cells 212 and 213 and the supply flow channel W1 are connected in parallel to the first manifold 22. Therefore, as compared with the structure in which only the end cells 212 and 213 are connected in series to the first manifold 22 as shown in FIG. 3, the fuel cell system 10 of the present embodiment has a higher anode gas It is possible to reduce the pressure loss.

(3) The branch flow passages W21 and W22 branch from the upstream portion of the supply flow passage W1 in the flow direction of the anode gas with respect to the fuel circulation portion 70, and branch into the right end internal flow passage 232 and the left end portion of the second manifold 23. Each is connected to the internal flow path 233. With such a configuration, it is possible to reduce the pressure loss of the anode gas even when the fuel circulation unit 70 is provided in the fuel cell stack 20.

(4) The branch flow passages W21 and W22 are respectively provided with open/close valves 64 and 66 capable of opening and closing them. As a result, the pressure of the anode gas supplied from the branch flow passages W21, W22 to the right end internal flow passage 232 and the left end internal flow passage 233 of the second manifold 23 is increased by the opening/closing operation of the open/close valves 64, 66. You can By increasing the pressure of the anode gas, the steam generated in the end cells 212, 213 can be flushed to the downstream side, so that it becomes difficult for the steam to be stored in the end cells 212, 213. As a result, water droplets are less likely to be generated in the respective anode gas flow paths Wa of the end cells 212, 213, so that fuel deficiency in the end cells 212, 213 due to the generation of water droplets can be avoided in advance. ..

(5) The fuel cell stack 20 has a structure in which end cells 212 and 213 are arranged at both ends of a laminated structure of a plurality of central cells 211. In the fuel cell stack 20 having such a structure, the temperature of the end cells 212, 213 is likely to be lower than that of the central cell 211, so that the end cells 212, 213 are deficient in fuel due to the generation of water droplets. Is likely to occur. Therefore, it is significant to adopt the structure like the fuel cell system 10 of the present embodiment.

<Second Embodiment>
Next, a second embodiment of the fuel cell system 10 will be described. Hereinafter, differences from the fuel cell system 10 of the first embodiment will be mainly described.
As shown in FIG. 4, in the fuel cell system 10 of the present embodiment, the first bypass flow passage W31 that connects the portion of the first branch flow passage W21 on the downstream side of the on-off valve 64 and the circulation flow passage W4. Is provided. Further, the fuel cell system 10 of the present embodiment is provided with the second bypass flow passage W32 that connects the portion of the second branch flow passage W22 on the downstream side of the opening/closing valve 66 and the circulation flow passage W4.

The first bypass flow passage W31 is provided with an opening/closing valve 81 that opens and closes the flow passage W31. Similarly, an opening/closing valve 82 that opens/closes the flow passage W32 is provided in the second bypass flow passage W32. In the present embodiment, the opening/closing valves 64 and 66 correspond to the branch passage opening/closing valves, and the opening/closing valves 81 and 82 correspond to the bypass passage opening/closing valves.

Next, an operation example of the fuel cell system 10 of this embodiment will be described.
In the fuel cell system 10 of the present embodiment, the open/close valves 81 and 82 are both set to the closed state, and then the open/close valves 64 and 66 are intermittently opened/closed, which is indicated by an alternate long and short dash line arrow in FIG. 4. Such an anode gas flow can be realized. That is, the same flow of anode gas as that of the fuel cell system 10 of the first embodiment can be realized. Therefore, in this case, it is possible to obtain the same operation and effect as the fuel cell system 10 of the first embodiment.

On the other hand, in the fuel cell system 10 of the present embodiment, the open/close valves 81 and 82 are both set to the open state, and then the open/close valves 64 and 66 are set to the closed state. It is possible to realize the flow of the anode gas as shown by. That is, the anode gas flowing into the first manifold 22 is supplied to the central cell 211, the right end cell 212, and the left end cell 213, respectively. Power generation is performed in the center cell 211, the right end cell 212, and the left end cell 213 based on this anode gas. The anode exhaust gas discharged after being used for power generation in the cells 211 to 213 is collected in the central internal flow passage 231, the right end internal flow passage 232, and the left end internal flow passage 233 of the second manifold 23, respectively.

The anode exhaust gas collected in the central internal flow passage 231 of the second manifold 23 flows to the fuel circulation unit 70 or the discharge flow passage W5 via the circulation flow passage W4. Further, the anode exhaust gas collected in the right end internal flow passage 232 of the second manifold 23 flows into the circulation flow passage W4 through the first branch flow passage W21 and the first bypass flow passage W31, and then the fuel circulation portion 70 or the exhaust flow. Flow to road W5. Further, the anode exhaust gas collected in the left end internal flow passage 233 of the second manifold 23 flows into the circulation flow passage W4 through the second branch flow passage W22 and the second bypass flow passage W32, and then the fuel circulation portion 70 or the exhaust flow. Flow to road W5.

According to the fuel cell system 10 of the present embodiment described above, it is possible to further obtain the action and effect shown in the following (6).
(6) By switching the open/closed states of the branch flow passage open/close valves 64, 64 and the open/closed states of the bypass flow passage open/close valves 81, 82, the flow of the anode gas as shown by the arrow in FIG. It is possible to realize the flow of the anode gas as shown by the arrow. That is, according to the fuel cell system 10 of the present embodiment, it is possible to switch the flow of the two types of anode gas, so that it is possible to improve convenience.

<Other Embodiments>
In addition, each embodiment can also be implemented in the following forms.
The fuel circulation unit 70 can be omitted from the fuel cell system 10 of each embodiment. When the fuel circulation unit 70 is omitted, the anode exhaust gas flowing into the circulation flow passage W4 may be directly discharged from the discharge flow passage W5.

The present disclosure is not limited to the above specific examples. A person skilled in the art appropriately modified the above-described specific examples is also included in the scope of the present disclosure as long as the features of the present disclosure are provided. The elements included in the above-described specific examples, and the arrangement, conditions, shapes, and the like of the elements are not limited to those illustrated, but can be appropriately changed. The respective elements included in the above-described specific examples can be appropriately combined as long as there is no technical contradiction.

W1: Supply flow path W4: Circulation flow path W21, W22: Branch flow path W31, W32: Bypass flow path 10: Fuel cell system 20: Fuel cell stack 21: Cell 22: First manifold 23: Second manifold 30: Fuel Supply units 64 and 66: open/close valve (branch flow path open/close valve)
70: Fuel circulation unit 81, 82: Open/close valve (bypass flow path open/close valve)
211: Central cell (first cell)
212: Right end cell (second cell)
213: Leftmost cell (second cell)
231: 1st internal flow path 232, 233: 2nd internal flow path

Claims (5)

A fuel cell stack (20) composed of a laminated structure of a plurality of cells (21) that generate electric energy by the reaction of an anode gas and a cathode gas;
A first manifold (22) connected to one end of each of the plurality of cells;
A second manifold (23) connected to the other end of each of the plurality of cells and having independent first internal flow paths (231) and second internal flow paths (232, 233);
A fuel supply unit (30) for supplying anode gas to the first manifold through a supply flow path (W1);
A branch flow path (W21, W22) for guiding a part of the anode gas flowing through the supply flow path to the second internal flow path of the second manifold,
In the cell,
One end is connected to the first manifold, the other end is connected to the first internal flow path of the second manifold, and the anode gas flows in a direction from the first manifold to the second manifold. The cell (211),
One end is connected to the first manifold and the other end is connected to the second internal flow path of the second manifold, and the anode gas flows in a direction from the second manifold to the first manifold. A fuel cell system including cells (212, 213). The fuel cell system according to claim 1, further comprising a branch passage opening/closing valve (64, 66) capable of opening/closing the branch passage. A fuel circulation unit (70) is provided in the middle of the supply passage, and circulates the anode gas collected in the first internal passage of the second manifold to the supply passage through the circulation passage (W4). Prepare,
The branch flow passage is branched from a portion of the supply flow passage upstream of the fuel circulation portion in the flow direction of the anode gas and is connected to the second internal flow passage of the second manifold. Or the fuel cell system according to item 2. A bypass flow path (W31, W32) for connecting the branch flow path and the circulation flow path,
The fuel cell system according to claim 3, further comprising a bypass flow passage opening/closing valve (81, 82) that opens and closes the bypass flow passage. The fuel cell system according to any one of claims 1 to 4, wherein the fuel cell stack has a structure in which the second cells are arranged at ends of a laminated structure of a plurality of the first cells.

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