JP5102574B2 - Fuel cell system - Google Patents

Description

  The present invention relates to a fuel cell system including a gas-liquid separator.

  In recent years, a polymer electrolyte fuel cell (PEFC) that generates electricity by generating an electrochemical reaction by supplying hydrogen (fuel gas) to the anode and oxygen (oxidant gas) to the cathode, etc. The fuel cell has attracted attention. Since the anode off gas discharged from the anode of such a fuel cell contains unreacted hydrogen, the anode off gas is returned to the upstream side of the fuel cell and supplied to the fuel cell to circulate the hydrogen. Is used efficiently.

However, the fuel cell generates moisture (water vapor) at the cathode as power is generated, and part of the moisture permeates the electrolyte membrane toward the anode. The permeated moisture is discharged from the anode together with unreacted hydrogen. That is, the anode off gas contains moisture in addition to unreacted hydrogen. When the anode off gas is returned upstream of the fuel cell in order to increase the utilization efficiency of hydrogen, the moisture is also returned upstream and supplied to the fuel cell. End up.
If it does so, there exists a possibility that a water | moisture content may adhere to the pore of the anode comprised with porous bodies which have electroconductivity, such as carbon paper, and it will block the pore. If the pores are blocked in this way, the power generation performance (current-voltage characteristics) of the fuel cell may be reduced.

  Therefore, there is a technique for returning the anode off-gas upstream of the fuel cell and arranging a gas-liquid separator in a hydrogen circulation pipe (fuel gas circulation pipe) for circulating hydrogen, and separating the moisture in the anode off-gas by this gas-liquid separator. It has been proposed (Patent Document 1).

JP 2003-317753 A

  By the way, in order to suitably separate the moisture in the anode off gas, the gas-liquid separator becomes large. On the other hand, when the gas-liquid separator is enlarged, it becomes difficult to mount the fuel cell system including the gas-liquid separator on a vehicle or the like having a limited mounting space.

  Therefore, an object of the present invention is to provide a fuel cell system capable of suitably separating water in the anode offgas without increasing the size of the gas-liquid separator.

As means for solving the above-mentioned problems, the present invention provides a fuel cell that generates power by supplying fuel gas to the anode and oxidant gas to the cathode, and fuel gas supplied from the fuel gas source to the fuel cell. The fuel gas supply pipe through which the fuel gas flows, the anode off gas discharged from the anode of the fuel cell is returned to the fuel gas supply pipe, and the fuel gas circulation pipe for circulating the fuel gas is disposed in the fuel gas circulation pipe. A gas-liquid separator that separates moisture in the off-gas, and a diluter that dilutes the anode off-gas with a dilution gas and that is fed with the moisture separated by the gas-liquid separator and discharges the moisture to the outside. wherein the fuel gas circulation piping between said gas-liquid separator and the fuel cell, distribution of the cylindrical body to extend substantially the same diameter along the flow direction of the anode off-gas , And the from the inner surface of the pipe, a fuel cell system characterized in that it has a projecting portion projecting toward the inside.

According to such a fuel cell system, the fuel gas circulation pipe (tubular pipe) between the fuel cell and the gas-liquid separator extends with substantially the same diameter along the flow direction of the anode off gas. Therefore, the strength of the pipe of the cylindrical body can be increased, and even when subjected to vibration, it is difficult to break. In addition, when the anode off gas collides with the protruding portion protruding inward from the inner surface of the pipe of the cylindrical body, the sprayed moisture (water vapor) in the anode off gas is condensed, that is, water droplets are formed. To be separated. The condensed moisture (condensed water) is pushed by the anode off-gas toward the gas-liquid separator, flows into the gas-liquid separator, is collected by the gas-liquid separator, and is discharged from the diluter to the outside . Thereby, the water | moisture content in the anode off gas which flows into fuel gas supply piping can be reduced via a part of fuel gas circulation piping ( piping of a cylindrical body) from a gas-liquid separator.

In this way, without increasing the size of the gas-liquid separator, the protruding portion protruding inward from the inner surface of the fuel gas circulation pipe between the fuel cell and the gas-liquid separator allows the Moisture can be condensed and separated. Accordingly, the fuel cell system can be easily mounted on a vehicle or the like where the mounting space is limited.
In addition, in the circulation direction of the anode off gas, a plurality of protrusions may be provided. When the protrusions are provided in this way, the interval between the adjacent protrusions is gradually increased toward the gas-liquid separator. The protrusion height may be gradually increased by narrowing.

Further, in the fuel cell system, the protruding portion has a ring shape.
According to such a fuel cell system, the water in the anode off gas can be separated by the ring-shaped protrusion.
In addition, if a plurality of ring-shaped protrusions are arranged at an appropriate interval in the anode off-gas flow direction, the plurality of ring-shaped protrusions are provided between the fuel cell and the gas-liquid separator. The strength (fatigue strength) of the fuel gas circulation pipe can be increased.

  A plurality of ring-shaped protrusions are provided along the pipe of the cylindrical body, and the protrusion height of the protrusion with respect to the inner peripheral surface of the pipe of the cylindrical body is the gas-liquid separator. The fuel cell system is characterized in that it gradually increases as it goes to.

  Further, in the fuel cell system, the protruding portion has a spiral shape.

  According to such a fuel cell system, the anode off-gas flows as a swirling flow by the spiral protrusion, and the anode off-gas easily collides with the protrusion. Thereby, the water | moisture content in anode off gas can be isolate | separated efficiently. Further, the strength of the pipe can be increased by the spiral protrusion.

  In the fuel cell system, a vertically lower portion of the protruding portion is cut out so that the generated condensed water flows along the flow direction of the anode off gas.

  According to such a fuel cell system, since the vertically lower part of the projecting part is cut out, the generated condensed water flows along the cut-off part along the circulation direction of the anode off gas. Thereby, the drainage of condensed water can be improved.

  Further, in the fuel cell system, the protruding portion extends along the flow direction of the anode off gas.

  According to such a fuel cell system, the discharge of condensed water can be guided by the protruding portion extending along the gas flow. Further, the strength of the pipe can be increased by the protruding portion extending along the gas flow.

  ADVANTAGE OF THE INVENTION According to this invention, the fuel cell system which can isolate | separate the water | moisture content in anode off gas suitably, without enlarging a gas-liquid separator can be provided.

<< First Embodiment >>
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 to 3.

≪Configuration of fuel cell system≫
A fuel cell system 1 according to this embodiment shown in FIG. 1 is mounted on a fuel cell vehicle (moving body) (not shown). The fuel cell system 1 includes a fuel cell stack 20, an anode system that supplies and discharges hydrogen (fuel gas) to and from the anode of the fuel cell stack 20, and air that contains oxygen to the cathode of the fuel cell stack 20 (oxidant) And a cathode system for supplying and discharging gas).

<Fuel cell stack>
The fuel cell stack 20 is a stack formed by stacking a plurality of (for example, 200 to 400) solid polymer type single cells, and the plurality of single cells are connected in series. The single cell includes an MEA (Membrane Electrode Assembly) and two conductive separators sandwiching the MEA. The MEA includes an electrolyte membrane (solid polymer membrane) made of a monovalent cation exchange membrane or the like, and an anode and a cathode (electrode) that sandwich the membrane.

  The anode and cathode are mainly composed of a conductive porous material such as carbon paper, and contain a catalyst (Pt, Ru, etc.) for causing an electrode reaction in the anode and cathode.

  Each separator is formed with a groove for supplying hydrogen or air to the entire surface of each MEA, and through holes for supplying and discharging hydrogen or air to all single cells. It functions as a passage 21 (fuel gas passage) and a cathode passage 22 (oxidant gas passage). Then, when hydrogen is supplied to each anode via the anode flow channel 21 and air is supplied to each cathode via the cathode flow channel 22, an electrode reaction occurs, and a potential difference (OCV (Open Circuit Voltage) is generated in each single cell. ), Open circuit voltage). When the fuel cell stack 20 and an external circuit such as a travel motor are electrically connected and a current is taken out, the fuel cell stack 20 generates power.

<Anode system>
The anode system includes a hydrogen tank 31 (fuel gas source), a shut-off valve 32, an ejector 33, a gas-liquid separator 34, a purge valve 35, and a drain valve 36.
The hydrogen tank 31 is connected to the inlet of the anode flow path 21 via a pipe 31a, a shutoff valve 32, a pipe 32a, an ejector 33, and a pipe 33a. Then, when the shutoff valve 32 is opened by an ECU (Electronic Control Unit, not shown), hydrogen is supplied from the hydrogen tank 31 to the anode flow path 21 via the shutoff valve 32 and the like. It has become.
That is, in the present embodiment, the fuel gas supply pipe through which hydrogen (fuel gas) supplied from the hydrogen tank 31 (fuel gas source) to the fuel cell stack 20 flows includes pipes 31a, 32a, 33a, an ejector 33, and the like. It is configured.

  The outlet of the anode channel 21 is connected to the gas-liquid separator 34 via the pipe 10A, and the anode off-gas containing unreacted hydrogen discharged from the anode channel 21 (anode) is gas-liquid separator 34. To be introduced. In the gas-liquid separator 34, water vapor (moisture) in the anode off-gas is separated.

  The gas-liquid separation method in the gas-liquid separator 34 may be any method in the present embodiment. For example, the gas-liquid separator 34 includes a refrigerant pipe through which a low-temperature refrigerant circulates, and this refrigerant pipe causes anode off-gas. Is cooled, water vapor is condensed and separated. As another gas-liquid separation method, the gas-liquid separator 34 includes a meandering flow path through which the anode off-gas flows, and the anode off-gas flows along the meandering flow path. In addition, water vapor in the anode off-gas is condensed and separated.

The anode off-gas having a reduced water vapor amount due to the separation of water vapor by the gas-liquid separator 34 is supplied to the ejector 33 via the pipe 34a. Then, hydrogen in the anode off gas is supplied again to the anode flow path 21 (anode).
That is, in the present embodiment, the anode gas is returned to the fuel gas supply pipe constituted by the pipe 31a and the like, and the fuel gas circulation pipe for circulating hydrogen (fuel gas) includes the pipe 10A and the pipe 34a. Has been. And the gas-liquid separator 34 is arrange | positioned at the fuel gas circulation piping comprised from piping 10A, 34a.

  The middle of the pipe 34a is connected to the diluter 42 through a pipe 35a, a normally closed purge valve 35, and a pipe 35b. When impurities (water vapor, nitrogen, etc.) in the anode off gas flowing through the pipe 34a exceed a predetermined amount, the purge valve 35 is opened by the ECU (not shown), and the anode off gas containing impurities is a diluter described later. 42 is discharged.

  The bottom of the gas-liquid separator 34 is connected to a diluter 42 via a pipe 36a, a normally closed drain valve 36, and a pipe 36b. When the recovered water separated by the gas-liquid separator 34 and the pipe 10A and recovered by the gas-liquid separator 34 exceeds a predetermined amount, the ECU (not shown) opens the drain valve 36. The recovered water is discharged to the diluter 42.

<Cathode system>
The cathode system includes a compressor 41 (oxidant gas supply means) and a diluter 42 (dilution device).
The compressor 41 is connected to the inlet of the cathode channel 22 via a pipe 41a. When the compressor 41 operates according to a command from an ECU (not shown), the compressor 41 takes in air containing oxygen and supplies it to the cathode channel 22. The pipe 41a is provided with a humidifier (not shown) that appropriately humidifies the air toward the cathode flow path 22.

The outlet of the cathode channel 22 is connected to the diluter 42 via a pipe 42 a, and the cathode off gas discharged from the cathode channel 22 (cathode) is introduced into the diluter 42.
The diluter 42 mixes the anode off-gas introduced from the anode system when the purge valve 35 is opened and the cathode off-gas (oxidant gas, dilution gas) discharged from the cathode channel 22 into the anode off-gas. This is a device for diluting hydrogen, and has a dilution space for mixing these gases and diluting hydrogen. The gas diluted by the diluter 42 is discharged to the outside (outside) through the pipe 42b.

<Piping connecting the anode channel and gas-liquid separator>
Next, the piping 10A that connects the anode channel 21 and the gas-liquid separator 34 will be described with reference to FIGS.
The pipe 10 </ b> A is a cylindrical body made of synthetic resin, and includes a plurality of ring-shaped (annular) protruding portions 11 protruding from the inner surface toward the center side (inner side). The plurality of protruding portions 11 are integrally formed on the inner surface of the pipe 10A by a core, an inner mold, or the like. However, the pipe 10A is not limited to being made of synthetic resin, but may be made of metal, for example.

The plurality of ring-shaped protrusions 11 collide with the anode off gas flowing through the pipe 10A. When such collision occurs, the sprayed moisture (water vapor) in the anode off gas is condensed, that is, , Water drops and become separated. Next, the condensed moisture (condensed water) is blown and pressed by the anode off-gas toward the gas-liquid separator 34, flows into the gas-liquid separator 34, and is collected by the gas-liquid separator 34.
It should be noted that the anode off-gas inlet of the gas-liquid separator 34 is arranged lower than the outlet of the anode channel 21 in the height direction so that the dew condensation water generated by the protrusions 11 easily flows into the gas-liquid separator 34. However, the pipe 10A may be configured to be inclined so as to gradually descend toward the gas-liquid separator 34.

  The inner diameter D1 of each ring-shaped protrusion 11 is designed to be larger than the minimum required inner diameter determined based on the fact that the anode off gas from the anode flow path 21 toward the gas-liquid separator 34 does not receive a great pressure loss. Yes. Thereby, the off-gas flowing through the pipe 10A can flow toward the gas-liquid separator 34 without greatly reducing the flow velocity.

≪Effect of fuel cell system≫
According to such a fuel cell system 1, the water vapor in the anode off-gas can be condensed and separated by the pipe 10 </ b> A connecting the outlet of the anode flow path 21 and the gas-liquid separator 34. That is, the moisture in the anode off gas can be separated without increasing the size of the gas-liquid separator 34, and the fuel cell system 1 is not increased in size. Thereby, the fuel cell system 1 can be easily mounted on a vehicle or the like in which a mounting space or the like is limited.

Further, by forming the protruding portion 11 on the inner peripheral surface of the pipe 10A, the water vapor in the anode off-gas can be separated without lengthening the pipe 10A.
Furthermore, the strength of the pipe 10 </ b> A can be increased by the plurality of protruding portions 11. For this reason, the pipe 10A is less likely to be damaged by vibrations received from the traveling fuel cell vehicle.

<< Modification of First Embodiment >>
Although the first embodiment of the present invention has been described above, the present invention is not limited to the first embodiment, and can be modified as follows, for example, without departing from the spirit of the present invention. In addition, you may combine suitably the structure which concerns on a modification, the structure of 2nd Embodiment mentioned later, etc.

  In the first embodiment described above, as shown in FIG. 2, the protruding heights of the plurality of protruding portions 11 from the inner peripheral surface of the pipe 10 </ b> A are the same. Alternatively, the protruding height may be gradually increased. Furthermore, although the interval between the adjacent protruding portions 11 is the same, for example, the interval may be gradually narrowed toward the gas-liquid separator 34.

  In the pipe 10A according to the first embodiment described above, the ring-shaped projecting portion 11 is formed by a core or the like, but as shown in FIG. The piping 10B in which the protruding portion 12 is formed may be used.

  In the first embodiment described above, the protruding portion 11 is ring-shaped, but may not be ring-shaped. For example, as shown in FIG. 5, a pipe 10 </ b> C in which a large number of protrusions 13 (protrusions) are formed on the inner peripheral surface by embossing. The pipe 10C is obtained, for example, by embossing one surface (or both surfaces) of a resin sheet to form a plurality of protrusions 13 and then forming the protrusions 13 into a cylindrical shape.

  Instead of the pipe 10A according to the first embodiment described above, as shown in FIG. 6, a pipe 10D having a spiral protrusion 14 formed on the inner surface may be provided. According to such a pipe 10 </ b> D, the anode off gas flows as a swirl flow by the spiral protrusion 14, and the anode off gas easily collides with the protrusion 14. Thereby, the water | moisture content in anode off gas can be isolate | separated efficiently.

  Instead of the pipe 10A according to the first embodiment described above, a pipe 10E shown in FIG. 7 may be provided. A plurality of ring-shaped protrusions 15 are formed on the inner surface of the pipe 10E, as in the case of the pipe 10A, but the vertically lower part of each protrusion 15 is notched and a notch 15a is formed. The notches 15a are aligned in a row in the flow direction of the anode off gas. Thereby, the dew condensation water produced | generated by each protrusion-like part 15 passes along the notch part 15a, is discharged | emitted toward the gas-liquid separator 34, and the drainage property of dew condensation water is improved.

  Instead of the pipe 10A according to the first embodiment described above, the pipe 10F shown in FIGS. 8 and 9 may be provided. The pipe 10F includes a plurality of fins 16 (heat exchange protrusions) in addition to the structure of the pipe 10A. The fins 16 are substantially C-shaped in the cross-section direction, and are inserted into circumferential grooves formed on the outer peripheral surface of the pipe 10F corresponding to the ring-shaped protrusions 11, and from the outer peripheral surface to the outside. Protrusively. And it is preferable that the fin 16 is metal in order to heat-exchange efficiently. The two fins 16 and 16 form a ring shape (see FIG. 9).

According to such a pipe 10 </ b> F, heat can be exchanged between the protrusion 11 and the outside air via the fins 16. Thereby, the temperature of the protrusion 11 can be lowered by outside air having a low normal temperature. Therefore, the temperature of the anode off gas that collides with the protrusion 11 can be suitably lowered, and the moisture in the anode off gas can be efficiently condensed and condensed.
However, the shape of the fin 16 (projection for heat exchange) is not limited to this, and may be other rod shapes.

<< Second Embodiment >>
Next, a second embodiment of the present invention will be described with reference to FIGS.
The fuel cell system according to the second embodiment includes a pipe 10G instead of the pipe 10A. Two protrusions 17 extending along the flow direction of the anode off gas are formed on the inner peripheral surface of the pipe 10G. The two protrusions 17 are formed at vertical vertical positions on the inner peripheral surface of the pipe 10G. However, the number of the protruding portions 17 is not limited to this, and may be four, for example, and may be arranged at equal intervals (90 °) in the circumferential direction.
According to such a pipe 10G, the dew condensation water generated in the projecting portion 17 can be discharged while being guided by the projecting portion 17 extending along the flow of the anode off gas.

<< Modification of Second Embodiment >>
In the above-described second embodiment, the case where the protrusions 17 are parallel to the anode off-gas flow direction is illustrated, but the protrusions 18 are formed slightly obliquely while extending along the anode off-gas flow direction. The pipe 10H may be used (see FIG. 13).
Alternatively, the projecting portion 19 may be a pipe 10I formed so as to meander while extending along the flow direction of the anode off gas (see FIG. 14).

It is a figure which shows the structure of the fuel cell system which concerns on 1st Embodiment. It is a sectional side view of piping concerning a 1st embodiment. FIG. 3 is a cross-sectional view taken along the line AA in FIG. It is a sectional side view of piping concerning a modification. It is a ring cut sectional view of piping concerning a modification. It is a sectional side view of piping concerning a modification. It is a ring cut sectional view of piping concerning a modification. It is a sectional side view of piping concerning a modification. FIG. 9 is a cross-sectional view taken along the line BB of FIG. It is a sectional side view of piping concerning a 2nd embodiment. It is CC sectional view taken on the line of FIG. 10 (ring cut sectional drawing). It is the DD sectional view taken on the line (plan sectional drawing) of FIG. It is a plane sectional view of piping concerning a modification. It is a plane sectional view of piping concerning a modification.

Explanation of symbols

1 Fuel cell system 10A-10I Piping (fuel gas circulation piping)
11-12, 14-15, 17-19 Projection 13 Projection (projection)
15a Notch 16 Fin (projection for heat exchange)
20 Fuel cell stack 31 Hydrogen tank (fuel gas source)
31a, 32a, 33a Piping (fuel gas supply piping)
34 Gas-liquid separator 34a Piping (fuel gas circulation piping)

Claims (6)

A fuel cell that generates power by supplying fuel gas to the anode and oxidant gas to the cathode; and
A fuel gas supply pipe through which fuel gas supplied from the fuel gas source to the fuel cell flows;
A fuel gas circulation pipe for returning the anode off-gas discharged from the anode of the fuel cell to the fuel gas supply pipe and circulating the fuel gas;
A gas-liquid separator disposed in the fuel gas circulation pipe and separating water in the anode off-gas;
A diluter that dilutes the anode off gas with a diluting gas and that is supplied with water separated by the gas-liquid separator and discharges the water to the outside.
With
The fuel gas circulation pipe between the fuel cell and the gas-liquid separator is a pipe having a cylindrical body extending with substantially the same diameter along the flow direction of the anode off gas, and extends from the inner surface of the pipe toward the inside. having a protruding portion protruding Te
A fuel cell system.   The fuel cell system according to claim 1, wherein the protrusion has a ring shape. A plurality of ring-shaped protrusions are provided along the pipe of the cylindrical body,
  3. The fuel cell system according to claim 2, wherein a protruding height of the protruding portion with respect to an inner peripheral surface of the pipe of the cylindrical body is gradually increased toward the gas-liquid separator.   The fuel cell system according to claim 1, wherein the protruding portion has a spiral shape. Vertically lower portion of the projecting portion, as generated dew condensation water flows along the flow direction of the anode off-gas, the claim 1, characterized in that are cut out in any one of claims 4 The fuel cell system described.   2. The fuel cell system according to claim 1, wherein the protrusion extends along a flow direction of the anode off gas.

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