Fuel cell system

Abstract

To provide a fuel cell system that can reduce the risk of water in the exhaust pipe flowing back into the fuel cell. [Solution] A fuel cell system comprising: a plurality of fuel cells; an exhaust pipe for discharging exhaust from the plurality of fuel cells; a connecting pipe connected in the middle of the exhaust pipe; and a tank for storing water that flows in from the exhaust pipe through the connecting pipe.

Description

Technical Field

[0001] The present disclosure relates to a fuel cell system.

Background Art

[0002] A fuel cell system is known that includes an exhaust pipe connected to each of a plurality of fuel cells, and the exhaust pipe discharges exhaust from those plurality of fuel cells.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Since a fuel cell generates electricity and water by the reaction of hydrogen and oxygen, the exhaust discharged from the fuel cell contains liquid water (drain water). However, in a conventional configuration where the exhaust pipe is connected to each of a plurality of fuel cells, water in the exhaust pipe (for example, drain water contained in the exhaust from the fuel cell or water condensed in the exhaust pipe from a part of the exhaust from the fuel cell) may flow back into any of the plurality of fuel cells. When the water in the exhaust pipe flows back into the fuel cell, for example, it may prevent the stable continuous operation of the fuel cell.

[0005] The present disclosure provides a fuel cell system capable of reducing the risk of water in the exhaust pipe flowing back into the fuel cell.

Means for Solving the Problems

[0006] As one aspect of the present disclosure, a plurality of fuel cells, an exhaust pipe that discharges exhaust from the plurality of fuel cells, a connecting pipe connected in the middle of the exhaust pipe, A fuel cell system is provided, comprising a tank for storing water that flows in from the exhaust pipe through the connecting pipe. [Effects of the Invention]

[0007] According to this disclosure, the risk of water in the exhaust pipe flowing back into the fuel cell is reduced. [Brief explanation of the drawing]

[0008] [Figure 1] This figure shows an example configuration of a fuel cell system according to the first embodiment. [Figure 2] This figure shows an example configuration of a fuel cell system according to the second embodiment. [Figure 3] This figure shows an example configuration of a fuel cell system according to the third embodiment. [Figure 4] This figure shows an example configuration of a fuel cell system according to the fourth embodiment. [Figure 5] This figure shows an example configuration of a fuel cell system according to the fifth embodiment. [Modes for carrying out the invention]

[0009] Several embodiments will be described below with reference to the accompanying drawings. However, this disclosure is not limited to these examples and is intended to include all modifications within the meaning and scope of the claims as indicated by the claims.

[0010] In the description and drawings of each embodiment, components having substantially the same or corresponding functional configurations may be denoted by the same reference numerals, thereby omitting redundant explanations. For ease of understanding, the scale of each part in the drawings may differ from that of the actual parts.

[0011] A degree of deviation is permissible in directions such as parallel, right angles, orthogonal, horizontal, vertical, up, down, left, right, front, and back, as long as it does not impair the function and effect of the embodiment. Parallel, right angles, orthogonal, horizontal, and vertical may include approximately parallel, approximately right angles, approximately orthogonal, approximately horizontal, and approximately vertical, respectively.

[0012] For example, "approximately parallel" means that two lines or two planes can be treated as parallel to each other, even if they are not perfectly parallel, as long as it is within the limits of what is permissible in manufacturing. Similarly, "approximately right angle," "approximately perpendicular," "approximately horizontal," and "approximately vertical" are intended to apply as long as the relative positions of the two lines or two planes are within the limits of what is permissible in manufacturing.

[0013] Figure 1 shows an example configuration of a fuel cell system according to the first embodiment. The fuel cell system 101 comprises a plurality of fuel cells 40 (in this example, two fuel cells 40a and 40b) and is a system capable of supplying electricity generated by at least one of the plurality of fuel cells 40 to a predetermined target. The fuel cell system 101 comprises a plurality of fuel cells 40, an exhaust pipe 81, a connecting pipe 30, and a tank 60. Some or all of the plurality of fuel cells 40 may be arranged vertically or horizontally.

[0014] In the following, when it is not necessary to distinguish between fuel cell 40a and fuel cell 40b, both fuel cell 40a and fuel cell 40b will be referred to as fuel cell 40.

[0015] The fuel cell 40 generates electricity through a chemical reaction between hydrogen SH supplied from the fuel pipe 41 and oxygen contained in the air SA supplied from the air inlet 42. The fuel cell 40 may also be a unit including a fuel cell module and auxiliary equipment.

[0016] The fuel cell module includes, for example, a fuel cell stack that generates electricity through a chemical reaction between hydrogen SH supplied from a fuel pipe 41 and oxygen contained in air SA supplied from an air inlet 42. The fuel cell stack has a stack structure in which a plurality of cells are stacked. The fuel cell stack is, for example, a polymer electrolyte fuel cell (PEFC). However, the fuel cell stack may also be other types of fuel cells such as a phosphoric acid fuel cell (PAFC), a solid oxide fuel cell (SOFC), or a molten carbonate fuel cell (MCFC).

[0017] The fuel cell module may include an air compressor that compresses the air SA supplied from the air inlet 42 and supplies it to the fuel cell stack, a coolant pump that circulates a coolant between a heat exchanger and the fuel cell stack, and the like.

[0018] The auxiliary devices included in the fuel cell 40 are devices for operating the fuel cell stack and assist the power generation operation of the fuel cell stack. The auxiliary devices may include at least one of a fuel pipe, an air pipe, an air filter, a heat exchanger, and the like. The fuel pipe is a pipe that supplies the hydrogen SH supplied from the fuel pipe 41 to the fuel electrode of the fuel cell stack. The air pipe is a pipe that supplies the air SA supplied from the air inlet 42 to the air electrode of the fuel cell stack. The air filter removes impurities from the air SA supplied from the air inlet 42. The air purified by the air filter is supplied to the air compressor through the air pipe. The heat exchanger cools the coolant by exchanging heat between the coolant for cooling the fuel cell stack and a heat source and a heat sink.

[0019] The exhaust pipe 81 discharges the exhaust EG from the plurality of fuel cells 40. The exhaust pipe 81 is connected to the exhaust port of each of the plurality of fuel cells 40. In the first embodiment, the exhaust pipe 81 includes a plurality of discharge pipes (in this example, two discharge pipes 81a and 81b) that separately discharge the exhaust EG from the plurality of fuel cells 40. The discharge pipe 81a is an exhaust pipe provided for the fuel cell 40a among the plurality of fuel cells 40, and discharges the exhaust EG from the exhaust port of the fuel cell 40a to the outside of the discharge pipe 81a through the exhaust outlet 82a. The discharge pipe 81b is an exhaust pipe provided for the fuel cell 40b among the plurality of fuel cells 40, and discharges the exhaust EG from the exhaust port of the fuel cell 40b to the outside of the discharge pipe 81b through the exhaust outlet 82b.

[0020] Since the fuel cell 40 generates water by the reaction of hydrogen and oxygen, the exhaust EG discharged from the fuel cell 40 contains liquid water (drain water). Further, since the exhaust EG contains drain water, the exhaust EG is considered to be in a state of saturated vapor. Because the exhaust EG is saturated vapor, when the exhaust pipe 81 cools, a part of the exhaust EG becomes water (condensate) condensed in the exhaust pipe 81. If the water EW such as drain water or condensate stays in the exhaust pipe 81 to an amount that cannot be pushed out by the pressure of the exhaust EG, there is a risk that the water EW will flow back to the fuel cell 40.

[0021] When the fuel cell 40 is filled with water EW due to the backflow of the water EW to the fuel cell 40, hydrogen and oxygen are not supplied to the fuel cell 40, and the power generation of the fuel cell 40 stops. Thus, when the water EW in the exhaust pipe 81 flows back to the fuel cell 40, there is a risk of disturbing the stable continuous operation of the fuel cell 40.

[0022] The fuel cell system 101 according to the first embodiment includes a connecting pipe 30 connected in the middle of the exhaust pipe 81 and a tank 60 for storing water EW flowing in from the exhaust pipe 81 through the connecting pipe 30, as means to reduce the risk of water EW in the exhaust pipe 81 flowing back into the fuel cell 40. By including the connecting pipe 30 and the tank 60, the fuel cell system 101 can store water EW in the exhaust pipe 81 in the tank 60. This reduces the risk of water EW accumulating in the exhaust pipe 81 and reduces the risk of water EW in the exhaust pipe 81 flowing back into the fuel cell 40. Therefore, the risk of the fuel cell 40 stopping power generation due to backflow of water EW into the fuel cell 40 is reduced, and the stability of continuous operation of the fuel cell 40 is improved.

[0023] The exhaust pipe 81 discharges exhaust gas EG, which does not contain water EW, as exhaust gas EA from exhaust outlets 82a and 82b. Since exhaust gas EA is released into the atmosphere through the exhaust pipe 81, it may be susceptible to external pressure OP such as atmospheric pressure or wind pressure. In this case, pressure fluctuations (pulsations) in the exhaust gas within the exhaust pipe 81 may occur, potentially causing water EW in the exhaust pipe 81 to flow back into the fuel cell 40. Furthermore, the accumulation of condensed water within the exhaust pipe 81 may reduce the cross-sectional area of ​​the flow path within the exhaust pipe 81, potentially causing pressure fluctuations (pulsations) within the exhaust pipe 81.

[0024] In the fuel cell system 101 according to the first embodiment, water EW in the exhaust pipe 81 flows into the tank 60 via the connecting pipe 30, so that pressure fluctuations in the exhaust pipe 81 caused by external disturbances such as external pressure OP and water stagnation can be released into the connecting pipe 30. As a result, pressure fluctuations (pulsations) in the exhaust pipe 81 are mitigated, and the risk of water EW in the exhaust pipe 81 flowing back into the fuel cell 40 is reduced.

[0025] The exhaust pipe 81a has an exhaust inlet 83a connected to the exhaust port 80a of the fuel cell 40a, and an exhaust outlet 82a for discharging exhaust EA to the outside of the exhaust pipe 81a. The exhaust pipe 81b has an exhaust inlet 83b connected to the exhaust port 80b of the fuel cell 40b, and an exhaust outlet 82b for discharging exhaust EA to the outside of the exhaust pipe 81b.

[0026] Since exhaust gas EA contains a gas with a lower density than air, exhaust outlet 82a may be located above exhaust port 80a, and exhaust outlet 82b may be located above exhaust port 80b. This promotes the discharge of exhaust gas EA from exhaust ports 80a and 80b to exhaust outlets 82a and 82b, thereby mitigating pressure fluctuations in the exhaust pipes 81a and 81b. As a result, pressure fluctuations (pulsations) in the exhaust pipe 81 are mitigated, reducing the risk of water EW in the exhaust pipe 81 flowing back into the fuel cell 40.

[0027] In the first embodiment, the connecting pipe 30 includes multiple connecting pipes (in this example, two connecting pipes 30a and 30b) that separately discharge water EW from multiple discharge pipes 81a and 81b. Connecting pipe 30a is a drain pipe provided for discharge pipe 81a among the multiple discharge pipes 81a and 81b, and discharges water EW from discharge pipe 81a to tank 60 from connection port 32a. Connecting pipe 30b is a drain pipe provided for discharge pipe 81b among the multiple discharge pipes 81a and 81b, and discharges water EW from discharge pipe 81b to tank 60 from connection port 32b. The diameter of connecting pipe 30a may be smaller than the diameter of discharge pipe 81a. The diameter of connecting pipe 30b may be smaller than the diameter of discharge pipe 81b.

[0028] In the first embodiment, since the multiple exhaust pipes 81a and 81b are not connected to each other, the exhaust EG, EA and water EW in exhaust pipe 81a do not merge with the exhaust EG, EA and water EW in exhaust pipe 81b within exhaust pipe 81. Therefore, it is possible to prevent the exhaust EG, EA and water EW flowing from the fuel cell 40a into exhaust pipe 81a from flowing back into the fuel cell 40b via exhaust pipe 81b. Similarly, it is possible to prevent the exhaust EG, EA and water EW flowing from the fuel cell 40b into exhaust pipe 81b from flowing back into the fuel cell 40a via exhaust pipe 81a.

[0029] In this example, connecting pipe 30a is connected to the middle of the discharge pipe 81a. Connecting pipe 30a allows the water EW in discharge pipe 81a to flow into tank 60 without merging with the water EW in discharge pipe 81b. Connecting pipe 30b is connected to the middle of the discharge pipe 81b. Connecting pipe 30b allows the water EW in discharge pipe 81b to flow into tank 60 without merging with the water EW in discharge pipe 81a. Note that connecting pipes 30a and 30b may be connected to each other in the middle and then connected to tank 60.

[0030] The connecting pipe 30a includes a connection port 31a that connects to the discharge pipe 81a and a connection port 32a that connects to the tank 60. The connecting pipe 30b includes a connection port 31b that connects to the discharge pipe 81b and a connection port 32b that connects to the tank 60. If the position of the connection port 31a is higher than the position of the connection port 32a, it can facilitate the flow of water EW in the discharge pipe 81a through the connecting pipe 30a to the tank 60. If the position of the connection port 31b is higher than the position of the connection port 32b, it can facilitate the flow of water EW in the discharge pipe 81b through the connecting pipe 30b to the tank 60. Due to its own weight, the water EW in the discharge pipes 81a and 81b is more likely to flow through the connecting pipe 30 to the tank 60 which is below the connecting pipe 30.

[0031] The connecting pipe 30a may be connected to a pipe fitting (for example, a tee pipe) located in the middle of the discharge pipe 81a via its connection port 31a, and the connecting pipe 30b may be connected to a pipe fitting (for example, a tee pipe) located in the middle of the discharge pipe 81b via its connection port 31b. This allows for easy connection between the connecting pipes 30a and 30b and the discharge pipes 81a and 81b.

[0032] The direction in which the connecting pipe 30a extends (for example, the straight line direction connecting connection port 31a and connection port 32a) may be inclined with respect to the vertical plane or parallel to the vertical plane. The direction in which the connecting pipe 30b extends (for example, the straight line direction connecting connection port 31b and connection port 32b) may be inclined with respect to the vertical plane or parallel to the vertical plane.

[0033] The connecting pipes 30a and 30b are preferably straight in order to facilitate the flow of water from the connection ports 31a and 31b towards the tank 60, but they may also be curved.

[0034] The tank 60 has a water storage area 68 for storing water EW that flows in from the exhaust pipe 81 via the connecting pipe 30. The water storage area 68 is the lower space inside the tank 60.

[0035] The fuel cell system 101 is equipped with a drain pipe 91 for draining the water EW accumulated in the water storage area 68 within the tank 60. By providing the drain pipe 91, the water EW can be discharged at a location away from the drain outlet of the tank 60.

[0036] The fuel cell system 101, by including a connecting pipe 30 and a tank 60, does not require a box-shaped gas-liquid separator for each fuel cell 40 to separate the water EW contained in the exhaust EG discharged from the fuel cell 40 within the case. The fuel cell system 101 can simplify the structure compared to a fuel cell system that includes a box-shaped gas-liquid separator for each fuel cell 40.

[0037] The fuel cell system 101 may also be equipped with a discharge pipe 140 for releasing gas from the tank 60. By providing the discharge pipe 140, gas accumulated in the tank 60 can be released to the outside. For example, even if unreacted hydrogen mixed in with water EW flowing in from the connecting pipe 30 accumulates in the tank 60, if the concentration of unreacted hydrogen is lower than the emission standard, it can be discharged into the atmosphere through the discharge pipe 140. By discharging unreacted hydrogen into the atmosphere through the discharge pipe 140, the risk of water EW containing unreacted hydrogen being discharged from the drain pipe 91 is reduced. Unreacted hydrogen is hydrogen contained in the exhaust gas EG that does not react with oxygen in the fuel cell 40.

[0038] Tank 60 may also be a water seal device that seals the connection ports 32a and 32b (drain outlets) of the connecting pipes 30a and 30b with water. The water seal device has a water seal tank into which water EW flows from the connection ports 32a and 32b of the connecting pipes 30a and 30b, and is a device that seals the inside of the connecting pipes 30a and 30b from the atmosphere with the water accumulated in the water seal tank. The connection ports 32a and 32b are sealed by being submerged in the water seal tank. The water seal device has an overflow pipe that discharges the water that overflows from the water seal tank to the drainage facility. The water seal pressure due to the water seal height in the water seal device reduces the risk of unreacted hydrogen leaking out of the fuel cell system 101 through the drain pipe 91.

[0039] Figure 2 shows an example configuration of a fuel cell system according to the second embodiment. In the second embodiment, the description of the configuration, operation, and effects similar to those of the first embodiment will be omitted by referring to the above description. The fuel cell system 102 according to the second embodiment shown in Figure 2 differs from the fuel cell system 101 according to the first embodiment in that it includes a water level gauge 150, a valve 160, and a controller 170.

[0040] The water level gauge 150 is a sensor that measures the water level in the tank 60. The valve 160 is an electrically operated control valve installed in the drain pipe 91, which adjusts the flow rate of water flowing through the drain pipe 91. The controller 170 adjusts the water level in the tank 60 to a predetermined level by adjusting the opening of the valve 160 based on the water level measured by the water level gauge 150. By adjusting the water level in the tank 60 to a predetermined level, the risk of water in the tank 60 flowing back into the connecting pipe 30 is reduced, and the risk of water in the tank 60 flowing back into the fuel cell 40 via the connecting pipe 30 is reduced.

[0041] The controller 170 may include electronic circuits such as a CPU (Central Processing Unit), GPU (Graphics Processing Unit), FPGA (Field Programmable Gate Array), or ASIC (Application Specific Integrated Circuit). The controller 170 may also be a computer having memory and a processor. The controller 170 may also be a programmable controller. The controller 170 performs the various control operations described in this specification by executing a program such as instruction code stored in memory, or by being circuit-designed for special applications.

[0042] The fuel cell system 102 may be equipped with an auto-drain in the drain pipe 91 that can adjust the water level in the tank 60, instead of the water level gauge 150, valve 160, and controller 170. The auto-drain has a valve that automatically opens and closes based on the pressure or time in the drain pipe 91, and by opening and closing the valve, the water level in the tank 60 is adjusted to a predetermined level. By adjusting the water level in the tank 60 to a predetermined level, the risk of water in the tank 60 flowing back into the connecting pipe 30 is reduced, and the risk of water in the tank 60 flowing back into the fuel cell 40 via the connecting pipe 30 is reduced.

[0043] The fuel cell system 102 may be equipped with a manual valve (e.g., a ball valve) in the drain pipe 91 that can adjust the water level in the tank 60, instead of the electric valve 160 and controller 170. The user adjusts the water level in the tank 60 to a predetermined level by adjusting the opening of the manual valve based on the water level measured by the water level gauge 150. By adjusting the water level in the tank 60 to a predetermined level, the risk of water in the tank 60 flowing back into the connecting pipe 30 is reduced, and the risk of water in the tank 60 flowing back into the fuel cell 40 via the connecting pipe 30 is reduced.

[0044] Figure 3 shows an example configuration of a fuel cell system according to the third embodiment. In the third embodiment, the explanation of the configuration, operation, and effects, which are the same as those of the embodiments described above, will be omitted by referring to the explanation above. The fuel cell system 103 according to the third embodiment shown in Figure 3 differs from the fuel cell system 102 according to the second embodiment in that the exhaust pipe 81 includes a confluence pipe 84.

[0045] In the fuel cell system 103, the exhaust pipe 81 includes multiple exhaust pipes 81a, 81b that separately discharge exhaust gases from multiple fuel cells 40, and a confluence pipe 84 connected to the multiple exhaust pipes 81a, 81b that discharges the exhaust gases EG from the multiple exhaust pipes 81a, 81b together. The exhaust gases EG from the multiple exhaust pipes 81a, 81b are combined at the confluence point 84a and discharged together to the outside from the exhaust outlet 82 of the confluence pipe 84. The connecting pipe 30 is connected to the multiple exhaust pipes 81a, 81b, as in the embodiment described above.

[0046] The diameter of the junction pipe 84 is preferably larger than the diameter of either the discharge pipe 81a or 81b. The diameter of the connecting pipe 30a may be smaller than the diameter of the discharge pipe 81a. The diameter of the connecting pipe 30b may be smaller than the diameter of the discharge pipe 81b.

[0047] According to the third embodiment, the number of exhaust outlets of the exhaust pipe 81 can be reduced, which simplifies the design of the piping leading to the exhaust outlets. Reducing the number of exhaust outlets of the exhaust pipe 81 reduces the space required for the piping leading to the exhaust outlets, thus enabling miniaturization of the fuel cell system.

[0048] Figure 4 shows an example configuration of a fuel cell system according to the fourth embodiment. In the fourth embodiment, the explanation of the configuration, operation, and effects, which are the same as those of the embodiments described above, will be omitted by referring to the explanation above. The fuel cell system 104 according to the fourth embodiment shown in Figure 4 differs from the fuel cell system 103 according to the third embodiment in that the connecting pipe 30 is connected to the merging pipe 84.

[0049] In the fuel cell system 104, the connecting pipe 30 is connected to the confluence pipe 84. The exhaust EG from the multiple exhaust pipes 81a and 81b are combined at the confluence point 84a and discharged together to the outside from the exhaust outlet 82 of the confluence pipe 84.

[0050] The fuel cell system 104 according to the fourth embodiment is provided with a shut-off valve in at least one of the plurality of discharge pipes 81a, 81b. In this example, the fuel cell system 104 includes a shut-off valve 181 provided in the discharge pipe 81a and a shut-off valve 182 provided in the discharge pipe 81b.

[0051] When fuel cell 40a is operating and fuel cell 40b is stopped, the controller 170 opens the shut-off valve 181 and closes the shut-off valve 182. This blocks the flow path of the discharge pipe 81b, reducing the risk of exhaust EG discharged from the operating fuel cell 40a and water EW in the discharge pipe 81a and junction pipe 84 flowing back into the stopped fuel cell 40b. Similarly, when fuel cell 40b is operating and fuel cell 40a is stopped, the controller 170 opens the shut-off valve 182 and closes the shut-off valve 181. This blocks the flow path of the discharge pipe 81a, reducing the risk of exhaust EG discharged from the operating fuel cell 40b and water EW in the discharge pipe 81b and junction pipe 84 flowing back into the stopped fuel cell 40a.

[0052] If the fuel cell 40b is located below the fuel cell 40a, the exhaust pipe 81a may be inclined downward toward the connecting pipe 30. This further reduces the risk of exhaust EG discharged from the operating fuel cell 40b and water EW in the exhaust pipe 81b and junction pipe 84 flowing back into the stopped fuel cell 40a.

[0053] Figure 5 shows an example configuration of a fuel cell system according to the fifth embodiment. In the fifth embodiment, the explanation of the configuration, operation, and effects, which are the same as those of the embodiments described above, will be omitted by referring to the explanation above. The fuel cell system 105 according to the fifth embodiment shown in Figure 5 differs from the fuel cell system 104 according to the fourth embodiment in that the shut-off valve 181 is not provided in the discharge pipe 81a.

[0054] The controller 170 closes the shut-off valve 182 when the fuel cell 40a is operating and the fuel cell 40b is stopped. This blocks the flow path of the exhaust pipe 81b, reducing the risk of exhaust gas EG discharged from the operating fuel cell 40a and water EW in the exhaust pipe 81a and junction pipe 84 flowing back into the stopped fuel cell 40b.

[0055] In the fuel cell system 105, since the shut-off valve 181 is not provided in the discharge pipe 81a, if the fuel cell 40b is located below the fuel cell 40a, it is preferable that the discharge pipe 81a is inclined downward toward the connecting pipe 30. This reduces the risk of exhaust EG discharged from the operating fuel cell 40b and water EW in the discharge pipe 81b and junction pipe 84 flowing back into the stopped fuel cell 40a, even if the shut-off valve 181 is not provided in the discharge pipe 81a.

[0056] As described above, embodiments have been explained, but these embodiments are presented as examples only, and the present invention is not limited by these embodiments. The above embodiments can be implemented in various other forms, and various combinations, omissions, substitutions, and modifications are possible without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of Symbols]

[0057] 30,30a,30b connecting pipe 31a, 31b, 32a, 32b connection ports 40a,40b fuel cell 60 tanks 68 Water storage area 80a, 80b exhaust port 81 Exhaust pipe 81a,81b Discharge pipe 82, 82a, 82b Exhaust outlet 83a, 83b Exhaust Inlet 84 Confluence pipe 91 Drain pipe 101, 102, 103, 104, 105 Fuel cell systems 140 Release tube 150 Water level gauge 160 valves 170 Controllers 181,182 Shut-off valves

Claims

1. Multiple fuel cells, An exhaust pipe for discharging exhaust from multiple fuel cells, A connecting pipe connected in the middle of the exhaust pipe, A fuel cell system comprising a tank for storing water that flows in from the exhaust pipe through the connecting pipe.

2. The exhaust pipe includes a plurality of exhaust pipes that separately discharge exhaust gases from a plurality of fuel cells. The multiple discharge pipes are not connected to each other. The fuel cell system according to claim 1, wherein the connecting pipe is connected to a plurality of the discharge pipes.

3. The exhaust pipe includes a plurality of exhaust pipes that separately discharge exhaust gases from a plurality of fuel cells, and a confluence pipe connected to the plurality of exhaust pipes that discharges exhaust gases from the plurality of exhaust pipes. The fuel cell system according to claim 1, wherein the connecting pipe is connected to a plurality of the discharge pipes.

4. The exhaust pipe includes a plurality of exhaust pipes that separately discharge exhaust gases from a plurality of fuel cells, and a confluence pipe connected to the plurality of exhaust pipes that discharges exhaust gases from the plurality of exhaust pipes. The connecting pipe is connected to the merging pipe, The fuel cell system according to claim 1, wherein at least one of the plurality of discharge pipes is provided with a shut-off valve.

5. The plurality of fuel cells include a first fuel cell and a second fuel cell located below the first fuel cell, The plurality of exhaust pipes include a first exhaust pipe for discharging exhaust from the first fuel cell and a second exhaust pipe for discharging exhaust from the second fuel cell. The fuel cell system according to claim 4, wherein the first discharge pipe is inclined downward toward the connecting pipe.

6. The fuel cell system according to claim 5, wherein the shut-off valve is provided in the second discharge pipe.

7. The fuel cell system according to claim 6, wherein the shut-off valve is not provided in the first discharge pipe.

8. A drain pipe for draining the water in the tank, A fuel cell system according to any one of claims 1 to 7, comprising a discharge pipe for releasing gas from the tank.

9. The fuel cell system according to claim 8, further comprising an auto drain or valve in the drain pipe capable of adjusting the water level in the tank.

10. The fuel cell system according to claim 8, comprising: a water level gauge for measuring the water level in the tank; an electrically operated control valve provided in the drain pipe; and a controller for adjusting the water level in the tank by adjusting the opening degree of the control valve based on the water level measured by the water level gauge.

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