Drainage device for fuel cell, fuel cell and fuel cell system

Abstract

To provide a fuel cell drainage device, a fuel cell, and a fuel cell system that can smoothly drain water generated during power generation.SOLUTION: A drainage device 100 includes a dilution flow path that flows unburned fuel gas H1 discharged from a fuel cell 10 without contributing to power generation, a dilution fan that supplies air to the dilution flow path to dilute the unburned fuel gas H1, a water storage portion provided in the dilution flow path and storing water W separated from the unburned fuel gas H1, a drain pipe 11 connected to the water storage portion and discharging water W to an external tank 13, and an air return pipe 12 connected to the dilution flow path and returning gas in the external tank 13 to the dilution flow path.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a technology for draining water generated in a fuel cell. [Background technology]

[0002] Generally, some of the water produced during fuel cell power generation mixes with unburned hydrogen that did not contribute to the oxidation reaction and is discharged from the fuel cell together with the unburned hydrogen. In fuel cell systems installed in vehicles such as fuel cell vehicles, this discharged water passes through a dilution box that dilutes the unburned hydrogen and is then stored in a wastewater tank. Because the wastewater tank may contain insufficiently diluted unburned hydrogen in addition to water and air, the wastewater tank is sealed to prevent leakage. For the same reason, the drain pipe connecting the dilution box and the wastewater tank is also airtight. In such a sealed structure, when water is discharged from the fuel cell to the drain tank, gas in the drain tank with the same volume as the water flows through the drain pipe in the opposite direction to the water discharge. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-63920 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the above-mentioned conventional technology has a problem in that if the drain pipe becomes clogged due to drainage caused by vehicle vibrations or the like, smooth drainage into the drain tank may be hindered. Therefore, in the past, to prevent clogging, pipes with a diameter larger than necessary for the actual flow rate were used. This is because if the drain pipe becomes clogged, there is no way for gas to escape within the drain pipe, and the pressure of the gas remaining in the drain tank or drain pipe hinders drainage.

[0005] The present invention has been made in consideration of the above circumstances, and aims to provide a drainage device for a fuel cell, a fuel cell, and a fuel cell system that can smoothly drain water generated during power generation. [Means for solving the problem]

[0006] The drainage device for a fuel cell in this embodiment comprises a dilution flow path that allows the flow of unburned fuel gas discharged from the fuel cell without contributing to power generation, a dilution fan that supplies air to the dilution flow path to dilute the unburned fuel gas, a water storage section that is provided in the dilution flow path and stores water separated from the unburned fuel gas, a drainage pipe that is connected to the water storage section and discharges the water to an external tank, and an air return pipe that is connected to the dilution flow path and returns gas in the external tank to the dilution flow path.

[0007] In addition, the fuel cell system of this embodiment comprises a fuel cell that generates electricity by oxidizing fuel gas, a dilution flow path that flows unburned fuel gas discharged from the fuel cell without contributing to power generation, a dilution fan that supplies air to the dilution flow path to dilute the unburned fuel gas, a water storage section provided in the dilution flow path that stores water separated from the unburned fuel gas, a sealed drain tank that stores the water collected in the water storage section, a drain pipe connected to the water storage section that discharges the water to the drain tank, and an air return pipe connected to the dilution flow path that returns gas in the drain tank to the dilution flow path. [Effects of the Invention]

[0008] The present invention provides a drainage device for a fuel cell, a fuel cell, and a fuel cell system that can smoothly drain water produced during power generation. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram of a fuel cell system including a drainage device for a fuel cell according to an embodiment; [Figure 2] FIG. 2 is a schematic perspective view showing an example of a dilution box according to an embodiment. [Figure 3] 3 is a cross-sectional perspective view of the dilution box taken along line II in FIG. 2. [Figure 4] 2. FIG. 3 is a cross-sectional perspective view of the dilution box taken along line II-II in FIG. [Figure 5] 3 is a cross-sectional perspective view of the dilution box taken along line III-III in FIG. 2. [Figure 6] FIG. 4 is a front cross-sectional view of the dilution box taken along line IV-IV in FIG. 2. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. In the drainage and exhaust system described below, the "upstream side" refers to the side toward which unburned hydrogen or generated water flows during normal fuel cell operation, and is closer to the fuel cell. Conversely, the "downstream side" refers to the side toward which unburned hydrogen or generated water flows during normal fuel cell operation, and is farther from the fuel cell.

[0011] FIG. 1 is a schematic diagram of a fuel cell system (hereinafter simply referred to as "system") 200 including a drainage device 100 for a fuel cell 10 according to an embodiment. The system 200 according to the embodiment is suitably applied to, for example, an electric vehicle or a fuel cell vehicle such as a hybrid vehicle. 1, the system 200 is configured by connecting a fuel cell 10 to a power system 40 and various flow path systems 50, 60, and 70. The fuel cell 10 is configured by a stack of fuel cell units that generate electricity by reacting a fuel gas H, such as hydrogen, with an oxidizing gas, such as oxygen in the air. In the following, hydrogen H is used as an example of the fuel gas H, and air X containing oxygen is used as an example of the oxidizing gas.

[0012] In the power system 40, the power generated by the fuel cell 10 is supplied to a motor 42 and a battery 43 connected to the fuel cell 10 via a power management ECU 41. The power management ECU 41 is a computer that controls the outputs of the motor 42 and the battery 43 and the amount of power generated by the fuel cell 10.

[0013] The fuel cell 10 is connected to a coolant flow path system 50 that supplies a coolant to cool the fuel cell 10, an air flow path system 60 that supplies air X, and a fuel flow path system 70 that supplies hydrogen H. The refrigerant flow path system 50 is an annular flow path in which a refrigerant pump 51 circulates the refrigerant cooled by a heat exchanger (not shown). The air flow path system 60 is mainly composed of an air supply path 62 through which the air X flows, compressed by a compressor 61 and supplied to the fuel cell 10, and an air exhaust path 63 through which off-gas of the air X discharged from the fuel cell 10 flows. The off-gas of the air X flowing through the air exhaust path 63 is exhausted to the atmosphere outside the system 200.

[0014] The fuel flow path system 70 is mainly composed of a fuel supply path 72 that connects a high-pressure hydrogen tank 71 and the fuel cell 10, and a drainage / exhaust path 73 that discharges water W produced by power generation. By opening a shutoff valve 74 provided in the fuel supply path 72, the hydrogen H stored in the high-pressure hydrogen tank 71 is adjusted to a pressure of approximately 100 kPa and supplied to the fuel cell 10. The produced water W discharged to the drainage / exhaust path 73 is in a mixed state of gas and liquid phases, and is further mixed with unburned hydrogen (unburned fuel gas) H1 that did not contribute to power generation.

[0015] A drainage device 100 according to the embodiment is connected to the drainage and exhaust path 73. The produced water W and unburned hydrogen H1 in the fuel cell 10 that are discharged from the drainage and exhaust path 73 are separated into gas and liquid and the unburned hydrogen H1 is diluted in the drainage device 100. The produced water W separated from the unburned hydrogen H1 in the drainage device 100 is stored in a drainage tank 13 that is connected to the drainage device 100 via a drain pipe 11.

[0016] The drainage device 100 is composed of, for example, a gas-liquid separator 14, a dilution box 16, a drainage pipe 11, and an air return pipe 12. The gas-liquid separator 14 separates the produced water W, which is generated in large quantities in one power generation run, from the unburned hydrogen H1. Many products have been known for the gas-liquid separator 14, and such ready-made products may be used.

[0017] The dilution box 16 is connected downstream of the gas-liquid separator 14, and dilutes the unburned hydrogen H1 flowing in from the gas-liquid separator 14 to a concentration that allows it to be discharged outside the system and then discharged into the atmosphere. As will be described in detail later, the dilution box 16 also has a gas-liquid separation function that separates the produced water W from the unburned hydrogen H1. Therefore, if the produced water W does not interfere with the dilution or discharge of the unburned hydrogen H1 in the dilution box 16, the dilution box 16 may be connected directly to the fuel cell 10 without providing the gas-liquid separator 14. The drain pipe 11 connects the dilution box 16 and the drain tank 13, and allows the produced water W separated from the unburned hydrogen H1 to flow into the drain tank 13. The air return pipe 12 is a flow path pipe that is provided separately from the drain pipe 11 and connects the dilution box 16 and the drain tank 13. The drain pipe 11 and the air return pipe 12 are preferably made of a flexible material such as polyvinyl chloride.

[0018] Gas such as air (hereinafter referred to as "retained air G") may accumulate in the drainage tank 13 mixed with the produced water W. Since this retained air G may contain unburned hydrogen H1 that was not completely separated, the drainage tank 13 is sealed. Similarly, the inside of the drainage pipe 11 connecting the drainage device 100 and the drainage tank 13 is also kept airtight.

[0019] Next, the structure of the dilution box 16 and the connection relationship between the drain pipe 11 and the air return pipe 12 will be described in more detail with reference to FIGS. FIG. 2 is a schematic perspective view showing an example of the dilution box 16 in the embodiment. As shown in FIG. 2, the dilution box 16 is provided on its top or side with three air supply ports 17, 18, and 19 for supplying external air A into the dilution box 16.

[0020] Of these, the third air supply port 19, which is provided on the most downstream side, is provided with a dilution fan 33. An exhaust pipe 30 is connected to the third air supply port 19. The dilution fan 33 blows air A into the exhaust pipe 30 at a pressure on the order of Pa. In this way, an exhaust path (exhaust dilution space 23, described later) for unburned hydrogen H1 is formed along the air blowing direction downstream of the dilution fan 33. The unburned hydrogen H1 is finally diluted with air A supplied into the exhaust pipe 30 by the dilution fan 33 to a standard value that is safe for external discharge, and is then discharged into the atmosphere by the wind force of the dilution fan 33.

[0021] The water storage section 36, located in the lower half of the dilution box 16, has a bottom 36a shaped like the bottom of a ship, with a central portion lowered by one step. This bottom 36a is provided with a drain hole 15 (FIG. 4) to which a drain nipple 35 is attached. The produced water W separated from the unburned hydrogen H1 and stored in the water storage section 36 is drained to an external drain tank 13 via a drain pipe 11 connected to the drain nipple 35.

[0022] 3 is a cross-sectional perspective view of the dilution box 16 taken along line II in FIG. As shown in FIG. 3, the dilution box 16 is provided with dilution flow paths 21, 22, and 23 through which the unburned hydrogen H1 and the produced water W in a gas-liquid mixture state flow. The dilution flow paths 21, 22, 23 can be divided into three dilution spaces, for example, an inlet dilution space 21, a gas-liquid separation dilution space 22, and an exhaust dilution space 23 in this order from the upstream side. The produced water W is cooled and liquefied while circulating through the dilution flow paths 21, 22, 23 in the order of the inlet dilution space 21, the gas-liquid separation dilution space 22, and the exhaust dilution space 23. As the produced water W circulates through the dilution flow paths 21, 22, 23, the water is gradually separated from the unburned hydrogen H1. Furthermore, as the unburned hydrogen H1 circulates through the dilution flow paths 21, 22, 23, the water is mixed with the air A supplied from the air supply ports 17, 18, 19 to the dilution flow paths 21, 22, 23, and the unburned hydrogen H1 is gradually diluted.

[0023] Hereinafter, the manner in which the unburned hydrogen H1 is diluted and separated from the produced water W will be described more specifically for each of the spaces 21, 22, and 23 with reference to FIGS. FIG. 4 is a cross-sectional perspective view of the dilution box 16 taken along line II-II in FIG. FIG. 5 is a cross-sectional perspective view of the dilution box 16 taken along line III-III in FIG. FIG. 6 is a front cross-sectional view of the dilution box 16 taken along line IV-IV in FIG.

[0024] [Introducing dilution space 21] As shown in Figures 3 to 6, the inlet dilution space 21 and the gas-liquid separation dilution space 22 are separated by an upright dilution cylinder 25 and an upright partition plate 26. The upper end of the dilution cylinder 25 opens to the outside from the top surface of the dilution box 16, forming a first air supply port 17. Note that the dilution fan connected to the first air supply port 17 is not shown. In addition, inlets 27 and 28 are provided in the base portion of the dilution cylinder 25, one on the inlet dilution space 21 side and one on the gas-liquid separation dilution space 22 side, so as to contact the floor surface. These two inlets 27, 28 allow the inlet dilution space 21 and the gas-liquid separation / dilution space 22 to spatially communicate with each other.

[0025] The gas-liquid mixture of unburned hydrogen H1 and produced water W flows into the dilution introduction space 21 from the exhaust liquid inlet 29 at a high pressure on the order of kPa. The gas-liquid mixture flows into the dilution tube 25 from the inlet 27 of the dilution introduction space 21, where it is mixed with and diluted by the air A supplied from the first air supply port 17. Then, the water flows out from the inlet 28 on the gas-liquid separation / dilution space 22 side into the gas-liquid separation / dilution space 22. At this time, the produced water W that has flowed into the inlet / dilution space 21 as a liquid and the produced water W that has liquefied beyond the saturated water vapor amount also flow into the gas-liquid separation / dilution space 22 from the inlets 27, 28 along the floor surface.

[0026] [Gas-liquid separation and dilution space 22] The gas-liquid separation / dilution space 22 is vertically divided into an upper space 22a (22) and a water storage space 22b (22) by a raised floor plate 31. The water storage space 22b is the internal space of the water storage section 36. A cylindrical exhaust pipe 30 is disposed in the center of the gas-liquid separation / dilution space 22 so as to be embedded in the raised floor plate 31. The exhaust pipe 30 narrows the upper space 22a in the center, forming an upstream empty chamber 22a1 (22a) and a downstream empty chamber 22a2 (22a).

[0027] A second air supply port 18 is provided on the side surface of the downstream chamber 22a2. The dilution fan provided in the second air supply port 18 is also not shown. A number of ventilation holes 32 are provided on the surface of the exhaust pipe 30 on the downstream chamber 22a2 side. These ventilation holes 32 connect the gas-liquid separation / dilution space 22 and the exhaust / dilution space 23. Furthermore, an uprising pipe 34 extending to the water storage space 22b is opened in the raised floor board 31, so that the upper space 22a and the water storage space 22b are in communication with each other.

[0028] With this structure, the produced water W that has liquefied and flowed into the water storage space 22b through the inlet 28 flows directly along the floor surface of the water storage section 36 and is stored in the bottom 36a. Additionally, the unburned hydrogen H1 and water vapor W1 that flow into the water storage space 22b from the inlet 28 together with the produced water W rise inside the riser pipe 34 and flow into the upstream chamber 22a1 of the upper space 22a. The unburned hydrogen H1 and water vapor W1 that flow into the upstream chamber 22a1 flow along the upper outer surface of the exhaust pipe 30 and flow into the downstream chamber 22a2.

[0029] The unburned hydrogen H1 that flows into the downstream chamber 22a2 is further diluted with air A introduced through the second air supply port 18. The produced water W that has liquefied after flowing into the downstream chamber 22a2 flows down into the water storage space 22b from a water collection port 39 provided in the raised floor plate 31. As shown in FIG. 6, the produced water W that flows down into the water storage space 22b flows along the floor surface into the bottom 36a and is then discharged into the drain tank 13 via the drain hole 15 and the drain pipe 11. The water storage space 22b may be divided into a complex labyrinth structure using partitions (not shown) to lengthen the flow path of the produced water W and cool the high-temperature produced water W. The substantial circulation path of the gas may be substantially lengthened by providing partitions (not shown) at the boundary between the upstream chamber 22a1 and the downstream chamber 22a2 or within the downstream chamber 22a2. The unburned hydrogen H1 that has been separated from the liquid produced water W in the gas-liquid separation and dilution space 22 and diluted flows into the exhaust dilution space 23 through the vent hole 32 on the side of the exhaust pipe 30.

[0030] [Exhaust dilution space 23] The exhaust dilution space 23 is the space inside the exhaust pipe 30 . As shown in Figure 4, this exhaust pipe 30 is provided with an air return hole 24 and is connected to the air return pipe 12. When the produced water W flows into the drain tank 13 from the drain pipe 11 connected to the water storage section 36, the pressure in the drain tank 13 rises slightly. The stored air G that has accumulated in the drain tank 13 is forced into the air return pipe 12 by this pressure and returned to the exhaust dilution space 23. Therefore, the pressure in the drain tank 13 does not rise above a certain value even if water is supplied while the stored air G is still in the drain tank 13. This also applies when the produced water W blocks the drain pipe 11.

[0031] Therefore, even if the drain pipe 11 is blocked by wastewater W, the accumulated air G is prevented from forcibly flowing back up the blocked drain pipe 11 and obstructing the flow of wastewater W into the drain tank 13. In other words, smooth drainage from outside the system to the drain tank 13, which maintains airtightness, is ensured. Therefore, by returning the accumulated air G through the air return pipe 12, the drain flow rate can be increased, improving drainage efficiency. In addition, since it is no longer necessary to provide a backflow space for the accumulated air G within the drain pipe 11, a thinner and more flexible drain pipe 11 can be used without concern for blockage due to wastewater. By making the drain pipe 11 a thinner and more flexible hose, it can be stored compactly in a narrow space.

[0032] Furthermore, the exhaust / dilution space 23 along the airflow from the dilution fan 33 typically has a pressure on the order of Pa, which is lower than the pressure in the water storage space 22b, which has a pressure on the order of kPa. Therefore, the accumulated air G accumulated in the drain tank 13 is returned to the exhaust / dilution space 23 from the air return pipe 12 without flowing back through the drain pipe 11. By creating a pressure difference at the connection point between the drain pipe 11 and the air return pipe 12 in this way, the occurrence of backflow of the accumulated air G within the drain pipe 11 is suppressed.

[0033] Furthermore, it is more preferable that the air return hole 24 be provided downstream of the vent hole 32 in the exhaust dilution space 23. This is because, upstream of the vent hole 32 in the exhaust dilution space 23, the airflow of the dilution fan 33 is obstructed by unburned hydrogen H1 and the like that has flowed in through the vent hole 32, slowing down the airflow and increasing the pressure, making it difficult for the stored air G to return from the air return pipe 12. It is also desirable that the air return hole 24 be open downstream along the flow path in the dilution flow paths 21, 22, 23. This is to allow the stored air G returned from the air return pipe 12 to be carried more smoothly into the air currents in the dilution flow paths 21, 22, 23. The air return hole 24 does not have to be connected to the exhaust / dilution space 23. For example, the air return pipe 12 may be connected to the gas-liquid separation / dilution space 22.

[0034] As described above, according to the drainage device 100 of the embodiment, by providing the air return pipe 12, even if the water flowing through the drainage pipe 11 blocks the drainage pipe 11, the water can be drained smoothly without increasing the pressure in the drainage tank 13.

[0035] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, modifications, and combinations can be made without departing from the spirit of the invention. These embodiments and their variations are intended to be included in the scope of the invention and its equivalents as described in the claims, as well as in the scope and spirit of the invention.

[0036] For example, the external shape and internal structure of the dilution box vary depending on the product. Therefore, although the embodiment has been described with the exhaust pipe embedded in the raised floor board at the center of the dilution box, the position of the exhaust pipe varies significantly depending on the product. Furthermore, although the dilution flow path has been described with the dilution flow path roughly divided into three spaces, the internal structure of each space and the layout of the spaces also vary depending on the product. [Explanation of symbols]

[0037] 10... fuel cell, 11... drain pipe, 12... air return pipe, 13... drain tank, 14... gas-liquid separator, 15... drain hole, 16... dilution box, 17... first air supply port, 18... second air supply port, 19... third air supply port, 20 (21-23)... dilution flow path, 21... inlet dilution space, 22 (22a, 22b)... gas-liquid separation dilution space (upper space, water storage space), 22a1 (22a)... upstream chamber, 22a2 (22a)... downstream chamber, 23... exhaust dilution space, 24... air return hole, 25... dilution tube, 26... partition plate, 27... inlet, 28... inlet, 29... exhaust liquid inlet, 30... exhaust pipe, 31... high floor plate, 32... vent, 33... dilution fan, 34...riser pipe, 35...drain nipple, 36 (36a)...water storage section (bottom of water storage section), 39...water collection port, 40...electrical power system, 41...power management ECU, 42...motor, 43...battery, 50...refrigerant flow path system, 51...refrigerant pump, 60...air flow path system, 61...compressor, 62...air supply path, 63...air exhaust path, 70...fuel flow path system, 71...high-pressure hydrogen tank, 72...fuel supply path, 73...drainage exhaust path, 74...shutoff valve, 100...drainage device, 200...system, A...air, G...stored air, H...fuel gas (hydrogen), H1...unburned fuel gas (unburned hydrogen), W (W1)...produced water, drainage (water vapor), X...air.

Claims

1. a dilution flow path for allowing unburned fuel gas discharged from the fuel cell without contributing to power generation to flow; a dilution fan that supplies air to the dilution flow path to dilute the unburned fuel gas; a water reservoir provided in the dilution flow path for storing water separated from the unburned fuel gas; a drain pipe connected to the water storage section for discharging the water to an external tank; an air return pipe connected to the dilution flow path for returning gas in the external tank to the dilution flow path.

2. 2. The drainage device for a fuel cell according to claim 1, wherein the air return pipe is connected to the water storage portion at a position where the pressure is lower than a position where the drainage pipe is connected.

3. 3. The drainage device for a fuel cell according to claim 1, wherein the air return pipe is connected to the dilution flow path downstream of the airflow generated by the dilution fan.

4. an exhaust liquid inlet that introduces the unburned fuel gas into the dilution flow path; 4. The drainage device for a fuel cell according to claim 1, wherein the air return pipe is connected to the dilution flow path downstream of a position where the exhaust liquid inlet is provided.

5. 5. The drainage device for a fuel cell according to claim 1, wherein the air return hole to which the air return pipe is connected in the dilution flow path opens downstream along the flow path in the dilution flow path.

6. 6. The drainage device for a fuel cell according to claim 1, further comprising a gas-liquid separator provided upstream of the dilution flow path for separating water from the unburned fuel gas.

7. The drainage device for a fuel cell according to any one of claims 1 to 6, a drainage and exhaust path that discharges the water and the unburned fuel gas to the drainage device of the fuel cell.

8. a fuel cell that generates electricity by oxidizing fuel gas; a dilution flow path for allowing unburned fuel gas discharged from the fuel cell without contributing to power generation to flow; a dilution fan that supplies air to the dilution flow path to dilute the unburned fuel gas; a water reservoir provided in the dilution flow path for storing water separated from the unburned fuel gas; a sealed drainage tank for storing the water collected in the water storage section; a drain pipe connected to the water storage section and discharging the water into the drain tank; an air return pipe connected to the dilution flow path for returning gas in the drainage tank to the dilution flow path.

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