Fuel cell system

Abstract

The present invention relates to a fuel cell system. The fuel cell system (10) includes an exhaust gas merging portion (46). The exhaust gas merging portion (46) merges the cathode exhaust fluid containing moisture discharged from the cathode electrode side of the fuel cell stack (12) with the anode exhaust fluid containing moisture discharged from the anode electrode side of the fuel cell stack (12). In the exhaust gas merging portion (46), there are provided: a cathode discharge port (50) for discharging the cathode exhaust gas; an anode discharge port (52) for discharging the anode exhaust fluid; and a partition plate that separates the cathode discharge port (50) from the anode discharge port (52) on the upstream side of the merging portion (56) of the cathode discharge port (50) and the anode discharge port (52).

Description

Technical Field

[0001] The present invention relates to a fuel cell system that combines and discharges cathode exhaust gas and anode exhaust fluid. Background Art

[0002] A fuel cell generates electricity by causing an electrochemical reaction between a fuel gas (e.g., hydrogen) supplied to an anode electrode and an oxidant gas (e.g., compressed air) supplied to a cathode electrode. At this time, water is generated due to the chemical reaction. Most of the generated water is discharged from the fuel cell system together with the oxidant exhaust gas (cathode exhaust gas). In addition, a part of the generated water moves within the electrolyte membrane and moves to the anode electrode. Therefore, the fuel exhaust gas (anode exhaust gas) also contains moisture.

[0003] The anode exhaust gas containing moisture is separated by a gas-liquid separator into condensed water and a gas-phase component. The anode exhaust fluid containing a large amount of condensed water separated by the gas-liquid separator (hereinafter, referred to as the anode exhaust fluid) flows into an exhaust gas merging section and merges with the cathode exhaust gas. After the anode exhaust fluid merges with the cathode exhaust gas, it is discharged to the outside of the fuel cell system (for example, Japanese Unexamined Patent Application Publication No. 2017-157317).

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2017-157317 Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] However, in the exhaust gas merging section, there are cases where the moisture in the cathode exhaust gas flows back to the anode electrode and cases where the moisture in the anode exhaust fluid flows back to the cathode electrode.

[0009] Solutions to the Problems

[0010] Therefore, an object of the present invention is to provide a fuel cell system capable of preventing the backflow of moisture in the exhaust gas merging section.

[0011] One aspect of the following disclosure is a fuel cell system including an exhaust gas merging section that merges a cathode exhaust fluid containing moisture discharged from the cathode electrode side of a fuel cell stack and an anode exhaust fluid containing moisture discharged from the anode electrode side of the fuel cell stack. The exhaust gas merging section includes: a cathode discharge port that discharges the cathode exhaust fluid; an anode discharge port that discharges the anode exhaust fluid; and a partition plate that separates the cathode discharge port and the anode discharge port on the upstream side of the merging section of the cathode discharge port and the anode discharge port.

[0012] Effect of the Invention

[0013] The fuel cell system of the above view prevents the backflow of moisture in the exhaust gas confluence section.

[0014] The above objects, features, and advantages can be easily understood from the following description of the embodiments with reference to the accompanying drawings. Description of the Drawings

[0015] Figure 1 It is a structural diagram of the fuel cell system according to the embodiment.

[0016] Figure 2 is Figure 1 A front-side cross-sectional view of the exhaust gas confluence section of

[0017] Figure 3 is Figure 1 A back-side cross-sectional view of the exhaust gas confluence section of

[0018] Figure 4 is a diagram showing the Figure 2 and Figure 3 Function of the exhaust gas confluence section shown.

[0019] Figure 5 is a diagram showing the Figure 2 and Figure 3 Function of the exhaust gas confluence section in an inclined state shown. Detailed Description of the Preferred Embodiment

[0020] Hereinafter, preferred embodiments will be given, and the fuel cell system will be described in detail with reference to the accompanying drawings.

[0021] As Figure 1 shown, the fuel cell system 10 according to the present embodiment includes a fuel cell stack 12 (fuel cell).

[0022] The fuel cell stack 12 includes a fuel gas supply device 14 for supplying fuel gas and an oxidant gas supply device 16 for supplying oxidant gas. In the present embodiment, hydrogen is used as the fuel gas and compressed air is used as the oxidant gas.

[0023] The fuel cell stack 12 has a plurality of power generation single cells stacked thereon. Each power generation single cell has a structure in which an electrolyte membrane - electrode assembly is sandwiched by separators. The electrolyte membrane - electrode assembly includes a solid polymer electrolyte membrane. The solid polymer electrolyte membrane is formed, for example, of a thin film of perfluorosulfonic acid containing moisture or a thin film of hydrocarbons. The solid polymer electrolyte membrane has an anode electrode and a cathode electrode on both sides. The separator has a hydrogen flow path (fuel gas flow path) for supplying and discharging hydrogen to and from the anode electrode on the surface facing the anode electrode. The separator has an air flow path (oxidant gas flow path) for supplying and discharging air to and from the cathode electrode on the surface facing the cathode electrode.

[0024] The fuel cell stack 12 has a hydrogen inlet 12a, a hydrogen outlet 12b, an air inlet 12c, and an air outlet 12d. The hydrogen inlet 12a penetrates along the stacking direction of each power generation single cell and is connected to the supply side of the hydrogen flow path. The hydrogen outlet 12b penetrates along the stacking direction of each power generation single cell and is connected to the discharge side of the hydrogen flow path. The air inlet 12c penetrates along the stacking direction of each power generation single cell and is connected to the supply side of the air flow path. The air outlet 12d penetrates along the stacking direction of each power generation single cell and is connected to the discharge side of the air flow path.

[0025] The fuel gas supply device 14 has, for example, a hydrogen tank for storing high - pressure hydrogen. The fuel gas supply device 14 is connected to the hydrogen inlet 12a of the fuel cell stack 12 via a hydrogen supply path 18. The hydrogen supply path 18 supplies hydrogen to the fuel cell stack 12.

[0026] In the hydrogen supply path 18, an ejector 20 and an eductor 22 are provided in series. By creating a negative pressure inside the eductor 22, the eductor 22 sucks hydrogen from the hydrogen circulation path 24.

[0027] A hydrogen discharge path 26 is connected to the hydrogen outlet 12b of the fuel cell stack 12. The hydrogen discharge path 26 leads out a hydrogen discharge gas (anode exhaust gas) which is hydrogen that has been at least partially used in the anode electrode from the fuel cell stack 12.

[0028] A gas - liquid separator 28 is connected to the hydrogen discharge path 26. The gas - liquid separator 28 separates the anode exhaust gas containing a large amount of moisture into an anode discharge fluid containing a large amount of condensed water and hydrogen from which the condensed water has been separated. The anode discharge fluid contains liquid - phase water and hydrogen. A hydrogen circulation path 24 is connected to the gas - liquid separator 28. The hydrogen separated by the gas - liquid separator 28 flows into the hydrogen circulation path 24. The downstream side of the hydrogen circulation path 24 is connected to the eductor 22. In addition, a discharge path 30 for discharging the anode discharge fluid is connected to the bottom of the gas - liquid separator 28. The discharge path 30 discharges the anode discharge fluid separated by the gas - liquid separator 28. A drain valve 32 is provided in the middle of the discharge path 30.

[0029] The oxidant gas supply device 16 takes in atmospheric air (air), compresses it, and supplies it to the air supply passage 34. In the present embodiment, the oxidant gas supply device 16 includes an air pump 36. In order to compress and supply atmospheric air (air), the air pump 36 is configured as a compressor built into an electric motor as a rotational drive unit. That is, the air pump 36 compresses atmospheric air as the electric motor rotates, generating compressed air. The air pump 36 supplies the compressed air to the fuel cell stack 12 via the air supply passage 34.

[0030] The air supply passage 34 is connected to the air inlet 12c of the fuel cell stack 12 on the downstream side of the air pump 36. A humidifier 40 and a gas-liquid separator 42 are arranged in the middle of the air supply passage 34.

[0031] An air discharge passage 44 is connected to the air outlet 12d of the fuel cell stack 12. The air discharge passage 44 discharges the cathode exhaust gas, which is the compressed air used in the cathode electrode, from the fuel cell stack 12. A large amount of moisture is generated in the cathode electrode along with the electrochemical reaction of the power generation single cell. The moisture generated in the cathode electrode is discharged from the fuel cell stack 12 together with the cathode exhaust gas. That is, the cathode exhaust gas contains a large amount of moisture.

[0032] The air discharge passage 44 has a humidifier 40. The humidifier 40 is used to exchange moisture and heat between the compressed air supplied from the air pump 36 and the cathode exhaust gas. Further, the air discharge passage 44 has an exhaust gas confluence portion 46 on the downstream side of the humidifier 40. The exhaust gas confluence portion 46 is connected to the downstream end of the discharge passage 30.

[0033] The air pump 36 generates heat as air is compressed. A part of the compressed air is used for adjusting operating conditions such as cooling the electric motor and various devices. The exhaust gas (hereinafter referred to as balance air) used in the adjustment of various devices is discharged from an adjustment passage 38 connected to the air pump 36. The downstream side of the adjustment passage 38 is connected to the exhaust gas confluence portion 46. The balance air converges with the cathode exhaust gas and the anode discharge fluid in the exhaust gas confluence portion 46.

[0034] As Figure 2 and Figure 3 shown, the exhaust gas confluence portion 46 includes a cylindrical main body portion 47, a cathode discharge port 50, an anode discharge port 52, an adjustment passage discharge port 54, a confluence portion 56 for converging the fluids flowing out from these ports, and a partition plate 58.

[0035] The main body portion 47 is a cylindrical shape extending in the vertical direction in the set state, i.e., the direction of arrow C. The main body portion 47 has a hollow portion 47a inside. A partition plate 58 is provided in the hollow portion 47a. In the hollow portion 47a, the portion below the lower end portion 58a of the partition plate 58 is a confluence portion 56 where the cathode exhaust gas, the anode exhaust fluid, and the balance air converge. The flow path cross-sectional area of the confluence portion 56 of the main body portion 47 is larger than the sum of the cross-sectional areas of a throttle hole 62 (described later) of the cathode discharge port 50, the cross-sectional area of the anode discharge port 52, and the cross-sectional area of the adjustment flow path discharge port 54.

[0036] The upper part of the hollow portion 47a has an anode discharge region 64 and an adjustment flow path discharge region 66. The anode discharge region 64 is a region adjacent to the opening portion of the anode discharge port 52. The adjustment flow path discharge region 66 is a region adjacent to the opening portion of the adjustment flow path discharge port 54. The anode discharge region 64 and the adjustment flow path discharge region 66 are separated by the partition plate 58.

[0037] The cathode discharge port 50 is connected to the downstream side of the Figure 1 air discharge path 44. As Figure 2 shown, the cathode discharge port 50 protrudes downward from the upper end portion 47b of the main body portion 47 toward the inside of the hollow portion 47a. The cathode discharge port 50 has a cylindrical portion 60 extending in the vertical direction in the set state, i.e., the direction of arrow C. The cathode exhaust gas flows along the cylindrical portion 60.

[0038] At the lower end portion 60a of the cylindrical portion 60, the throttle hole 62 communicating with the confluence portion 56 opens downward. The cathode exhaust gas is discharged to the confluence portion 56 through the throttle hole 62. The flow path cross-sectional area of the throttle hole 62 is smaller than the flow path cross-sectional area of the cylindrical portion 60. The height of the lower end portion 60a of the cylindrical portion 60 having the throttle hole 62 is approximately the same as the height of the lower end portion 58a of the partition plate 58. The cylindrical portion 60 functions as a partition member that isolates the cathode exhaust gas from the fluid of the anode discharge port 52 and the fluid of the adjustment flow path discharge port 54.

[0039] As Figure 3 shown, the anode discharge port 52 is connected to the side portion near the upper end portion 47b of the main body portion 47. The anode discharge port 52 opens in the direction of arrow A (the lateral direction in the set state). The height of the lower end portion 52a of the anode discharge port 52 is the same as or higher than the lower end portion 60a (and the lower end portion 58a of the partition plate 58) of the cylindrical portion 60. In the illustrated example, the anode discharge port 52 is arranged so as to face the outer wall of the cylindrical portion 60. The arrangement position of the anode discharge port 52 is not limited to the illustrated example, and the axis of the anode discharge port 52 and the cylindrical portion 60 may also be offset.

[0040] The upper end portion 47b of the main body portion 47 has a bulging portion 47c that bulges upward. The adjustment flow path discharge port 54 is connected to the bulging portion 47c of the main body portion 47. The adjustment flow path discharge port 54 opens in the direction of arrow A (the lateral direction in the installed state). The opening position of the adjustment flow path discharge port 54 is at a position higher than the anode discharge port 52. In the present embodiment, the height H2 of the lower end portion 54a of the adjustment flow path discharge port 54 is higher than the height H1 of the lower end portion 60a of the cylindrical portion 60 of the cathode discharge port 50 (and the lower end portion 58a of the partition plate 58). Further, the adjustment flow path discharge port 54 and the anode discharge port 52 are arranged on opposite sides of the main body portion 47 across the central axis of the exhaust gas merging portion 46.

[0041] The partition plate 58 projects downward from the upper end portion 47b of the main body portion 47. The partition plate 58 is arranged between the adjustment flow path discharge port 54 and the anode discharge port 52. One end of the partition plate 58 is connected to the side wall of the main body portion 47. The other end of the partition plate 58 is connected to the cylindrical portion 60. The lower end portion 58a of the partition plate 58 extends to the same position as the lower end portion 60a of the cylindrical portion 60. The partition plate 58 divides the upper part of the merging portion 56 of the exhaust gas merging portion 46 into a region communicating with the adjustment flow path discharge port 54 and a region communicating with the anode discharge port 52.

[0042] The fuel cell system 10 of the present embodiment is configured as described above. Hereinafter, the operation of the exhaust gas merging portion 46 will be described.

[0043] As Figure 4 shown, the cathode exhaust gas containing a large amount of moisture is discharged from the cathode discharge port 50 to the exhaust gas merging portion 46. The cathode exhaust gas is discharged through the throttle hole 62 into the merging portion 56 having a cross-sectional area larger than that of the cathode discharge port 50. The cathode exhaust gas at the cathode discharge port 50 is throttled by the throttle hole 62. Thus, the internal pressure of the cathode discharge port 50 is higher than that of the merging portion 56. Therefore, backflow from the merging portion 56 side toward the cathode discharge port 50 can be prevented.

[0044] The condensed water contained in the cathode exhaust gas is guided by the cylindrical portion 60 to the throttle hole 62 in a state separated from the anode discharge port 52 and the adjustment flow path discharge port 54. The condensed water is violently discharged through the throttle hole 62 together with the cathode exhaust gas into the merging portion 56. Therefore, backflow of the condensed water of the cathode exhaust gas toward the anode discharge port 52 and the adjustment flow path discharge port 54 can be prevented. Further, the anode discharge fluid flows into the exhaust gas merging portion 46 from the anode discharge port 52. The anode discharge fluid is discharged into the merging portion 56 through the anode discharge region 64. The anode discharge region 64 is isolated from the adjustment flow path discharge region 66 by the partition plate 58. Therefore, the partition plate 58 prevents the condensed water contained in the anode discharge fluid from flowing back to the adjustment flow path discharge port 54.

[0045] Balanced air is discharged from the adjustment flow path outlet 54. The balanced air is guided to the confluence portion 56 through the adjustment flow path discharge area 66. The balanced air merges with the cathode exhaust gas and the anode exhaust fluid in the confluence portion 56 and dilutes them. In the present embodiment, since the cross-sectional area of the confluence portion 56 is larger than any one of the cross-sectional areas of the throttle hole 62, the anode outlet 52, and the adjustment flow path outlet 54, the internal pressure of the confluence portion 56 is maintained at a state lower than theirs. Therefore, it is possible to prevent the backflow of the fluid from the confluence portion 56 to the cathode outlet 50, the anode outlet 52, and the adjustment flow path outlet 54.

[0046] In addition, in the present embodiment, the lower end portion 54a of the adjustment flow path outlet 54 is located at a position higher than the lower end portion 58a of the partition plate 58. Thus, as Figure 5 shown, even when the conveyance device (such as a ship, a vehicle, or an aircraft) on which the fuel cell system 10 (refer to Figure 1 ) is installed is tilted, it is possible to prevent the inflow of condensed water into the adjustment flow path outlet 54. Thereby, it is possible to prevent the functional degradation caused by the backflow of condensed water to the air pump 36, and the reliability of the fuel cell system 10 is improved.

[0047] The fuel cell system 10 of the present embodiment exhibits the following effects.

[0048] The fuel cell system 10 of the present embodiment includes an exhaust gas confluence portion 46 that merges the moisture-containing cathode exhaust fluid (for example, cathode exhaust gas) discharged from the cathode electrode side of the fuel cell stack 12 with the moisture-containing anode exhaust fluid discharged from the anode electrode side of the fuel cell stack 12. The exhaust gas confluence portion 46 includes: a cathode outlet 50 that discharges the cathode exhaust fluid; an anode outlet 52 that discharges the anode exhaust fluid; and a partition plate (for example, including a cylindrical portion 60) that separates the cathode outlet 50 and the anode outlet 52 on the upstream side of the confluence portion 56 of the cathode outlet 50 and the anode outlet 52.

[0049] According to the fuel cell system 10 having the above structure, it is possible to prevent the backflow of the cathode exhaust fluid to the anode outlet 52 and the backflow of the anode exhaust fluid to the cathode outlet 50.

[0050] In the above fuel cell system 10, it is also possible that the cathode outlet 50 has a cylindrical portion 60 extending in the vertical direction and a throttle hole 62 provided at the lower end portion 60a of the cylindrical portion 60 and opening downward, the anode outlet 52 is disposed on the side of the cylindrical portion 60, and the cathode outlet 50 and the anode outlet 52 are separated by the cylindrical portion 60. According to the fuel cell system 10 having this structure, it is possible to prevent the backflow of the cathode exhaust fluid and the anode exhaust fluid.

[0051] In the above-described fuel cell system 10, it is also possible that the cross-sectional area of the throttle hole 62 is smaller than the cross-sectional area of the cylindrical portion 60. According to the fuel cell system 10 having this structure, the internal pressure of the cylindrical portion 60 can be made higher than the internal pressure of the confluence portion 56, and backflow of the fluid on the confluence portion 56 side can be prevented.

[0052] In the above-described fuel cell system 10, it is also possible that it further includes: an oxidant gas supply device 16 (for example, an air pump 36) that supplies an oxidant gas (for example, compressed air) to the fuel cell stack 12; and an adjustment flow path 38 that guides a part of the oxidant gas to the exhaust gas confluence portion 46. An adjustment flow path discharge port 54 connected to the adjustment flow path 38 is provided in the exhaust gas confluence portion 46, and the adjustment flow path discharge port 54 and the anode discharge port 52 are separated by a partition plate 58. According to the fuel cell system 10 having this structure, backflow of the anode discharge fluid to the adjustment flow path discharge port 54 can be prevented. Therefore, the phenomenon of condensed water flowing back into the air pump 36 can be prevented.

[0053] In the above-described fuel cell system 10, it is also possible that the adjustment flow path discharge port 54 and the anode discharge port 52 are arranged on opposite sides across the central axis of the exhaust gas confluence portion 46.

[0054] In the above-described fuel cell system 10, it is also possible that the lower end portion 58a of the partition plate 58 is formed to have the same height as the lower end portion 60a of the cylindrical portion 60. According to the fuel cell system 10 having this structure, the adjustment flow path discharge port 54 and the anode discharge port 52 can be separated on the upper side of the confluence portion 56 inside the exhaust gas confluence portion 46, and the phenomenon of condensed water contained in the anode discharge fluid flowing back to the adjustment flow path discharge port 54 can be prevented.

[0055] In the above-described fuel cell system 10, it is also possible that in the exhaust gas confluence portion 46, the adjustment flow path discharge port 54 of the adjustment flow path 38 is arranged at a position higher than the anode discharge port 52. According to the fuel cell system 10 having this structure, even when the fuel cell system 10 is tilted, backflow of condensed water to the adjustment flow path discharge port 54 can be prevented.

[0056] As described above, preferred embodiments of the present invention have been described, but the present invention is not limited to the above embodiments, and various changes can of course be made without departing from the gist of the present invention.

Claims

1. A fuel cell system, the fuel cell system having an exhaust gas confluence section that causes a cathode exhaust fluid containing moisture discharged from the cathode electrode side of a fuel cell stack to merge with an anode exhaust fluid containing moisture discharged from the anode electrode side of the fuel cell stack. In the fuel cell system, the exhaust gas confluence section includes: a cathode discharge port that discharges the cathode exhaust fluid; an anode discharge port that discharges the anode exhaust fluid; and a partition plate that separates the cathode discharge port and the anode discharge port on the upstream side of the confluence section of the cathode discharge port and the anode discharge port. The cathode discharge port has a cylindrical portion extending in the vertical direction and a throttle hole provided at the lower end portion of the cylindrical portion and opening downward. The anode discharge port is disposed on the side of the cylindrical portion, and the cathode discharge port and the anode discharge port are separated by the cylindrical portion.

2. The fuel cell system according to claim 1, characterized in that, The cross-sectional area of the throttle hole is smaller than the cross-sectional area of the cylindrical portion.

3. The fuel cell system according to claim 1 or 2, characterized in that, It further includes: an oxidant gas supply device that supplies oxidant gas to the fuel cell stack; and an adjustment flow path that guides a part of the oxidant gas to the exhaust gas confluence section. An adjustment flow path discharge port connected to the adjustment flow path is provided in the exhaust gas confluence section. The adjustment flow path discharge port and the anode discharge port are separated by the partition plate.

4. The fuel cell system according to claim 3, characterized in that, The adjustment flow path discharge port and the anode discharge port are arranged on opposite sides across the central axis of the exhaust gas confluence section.

5. The fuel cell system according to claim 3, wherein the lower end portions of the partition plates including the cylindrical portion are formed to have the same height.

6. The fuel cell system according to claim 3, characterized in that, In the exhaust gas confluence section, the adjustment flow path discharge port is disposed at a position higher than the anode discharge port.

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