JP2010003603A - Fuel cell stack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell stack in which liquid junction can be prevented certainly with a simple and compact structure and a superior power generation performance can be secured. <P>SOLUTION: A fuel gas exit manifold 100b communicating with a fuel gas exhaust communicating hole 76b is provided at an end plate 62b to constitute a fuel cell stack 10. An exit piping 120 is connected to the fuel gas exit manifold 100b and the top end 120a of this exit piping 120 protrudes toward outside from the end plate 62b and is inserted into a water collection tank 53. The water surface 124 at the maximum water level of water stored in a chamber 122 of the water collection tank 53 is established to be away farther below the top end 120a of the exit piping 120. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  In the present invention, a plurality of power generation cells are stacked, a reaction gas communication hole for flowing a reaction gas used in a power generation reaction in the stacking direction is provided, and an end plate disposed at one end in the stacking direction includes The present invention relates to a fuel cell stack in which a reaction gas outlet communicating with a reaction gas communication hole is opened.

  For example, in a polymer electrolyte fuel cell, an electrolyte membrane / electrode structure (an electrolyte / electrode structure) in which an anode electrode and a cathode electrode are disposed on both sides of an electrolyte membrane (electrolyte) made of a polymer ion exchange membrane, respectively. ) Is held by a separator. This type of fuel cell is normally used as a fuel cell stack by stacking a predetermined number of power generation cells.

  In a fuel cell, an internal manifold is often configured to supply a fuel gas and an oxidant gas, which are reaction gases, to the anode side electrode and the cathode side electrode of each of the stacked power generation cells. The internal manifold includes a reaction gas supply communication hole and a reaction gas discharge communication hole that are provided so as to penetrate in the stacking direction of the power generation cells. The fuel cell stack includes the reaction gas supply communication hole and the reaction gas discharge communication hole. A supply side pipe and a discharge side pipe communicating with the hole are connected. At that time, there is a risk of electric leakage from a connection portion between the fuel cell stack, the supply side pipe, and the discharge side pipe.

  Therefore, in order to suppress this type of leakage, for example, a fuel cell system disclosed in Patent Document 1 has been proposed. As shown in FIG. 7, the fuel cell system includes a fuel cell stack 1, and the fuel cell stack 1 includes a stacked body in which a plurality of cell modules 2 are stacked, and both ends of the stacked body in the stacking direction. Are provided with end plates 3a, 3b.

  One end plate 3a is connected to supply pipes 4a, 5a and 6a for humidified hydrogen gas, humidified air and coolant, and discharge pipes 4b, 5b and 6b. These supply pipes 4a to 6a and discharge pipes 4b to 6b are formed of an electrically insulating member.

JP-A-2005-332673

  However, in Patent Document 1 described above, in particular, the air discharge communication hole (not shown) that communicates with the discharge pipe 5b tends to condense generated water generated by power generation and generate stagnant water, while the discharge pipe 4b. In the hydrogen gas discharge communication hole (not shown) communicating with the water, moisture by back diffusion through the electrolyte membrane of the produced water is condensed and the retained water is likely to be generated.

  For this reason, the condensed water is discharged by the reaction gas discharge pressure in the discharge pipes 4b and 5b, and there is a problem that the metal members are electrically short-circuited (liquid junction) through the condensed water. In that case, it is conceivable to increase the insulation resistance by configuring the discharge pipes 4b and 5b to be considerably long. However, since the discharge pipes 4b and 5b are formed of an electrically insulating member, there is a problem in that insufficient strength is likely to occur due to the increase in length, and handling of the external pipes becomes complicated and the pipe structure becomes large. .

  The present invention solves this type of problem, and provides a fuel cell stack capable of reliably preventing liquid junctions and ensuring good power generation performance with a simple and compact configuration. With the goal.

  In the present invention, a plurality of power generation cells are stacked, and provided with a reaction gas supply communication hole and a reaction gas discharge communication hole through which a reaction gas used in a power generation reaction flows in the stacking direction, and disposed at one end in the stacking direction. The end plate relates to a fuel cell stack in which a reaction gas outlet communicating with the reaction gas discharge communication hole is opened.

  The fuel cell stack is connected to the reaction gas outlet, and an outlet pipe whose tip protrudes outward from the end plate, and collects moisture contained in the reaction gas discharged from the tip of the outlet pipe, and the outlet pipe And a water collecting mechanism arranged such that the water surface is positioned below the tip of the water.

  The fuel cell stack includes a reaction gas circulation system for circulating and supplying the reaction gas discharged from the reaction gas outlet to the reaction gas supply communication hole, and a water collection mechanism is provided in the reaction gas circulation system. It is preferable.

  According to the present invention, the reaction gas discharged to the reaction gas discharge communication hole is sent to the water collection mechanism through the outlet pipe, and the water contained in the reaction gas is caused to flow by the water collection mechanism. It has been collected.

  At that time, the water surface of the water collecting mechanism is located below the tip of the outlet pipe, and the conductive path between the water in the outlet pipe and the water in the water collecting mechanism is blocked. Therefore, it is possible to satisfactorily prevent the occurrence of a liquid junction with a simple and compact configuration.

  FIG. 1 is a schematic configuration diagram of a fuel cell system 12 incorporating a fuel cell stack 10 according to an embodiment of the present invention.

  The fuel cell system 12 is mounted on a fuel cell vehicle (not shown). The fuel cell stack 10, a cooling medium supply mechanism 16 for supplying a cooling medium to the fuel cell stack 10, and the fuel cell stack 10 are oxidized. An oxidant gas supply mechanism 18 for supplying an agent gas (reactive gas) and a fuel gas supply mechanism 20 for supplying a fuel gas (reactive gas) to the fuel cell stack 10 are provided.

  The cooling medium supply mechanism 16 includes a radiator 24. A cooling medium supply pipe 28 and a cooling medium discharge pipe 30 are connected to the radiator 24 via a refrigerant pump 26.

  The oxidant gas supply mechanism 18 includes an air pump 32, and an air supply pipe 34 connected at one end to the air pump 32 is connected at the other end to the humidifier 36. The fuel cell stack 10 is connected via the humidified air supply pipe 38. The fuel cell stack 10 and the humidifier 36 are connected to an off-gas supply pipe 40 for supplying an oxidant gas containing used generated water (hereinafter referred to as off-gas) as a humidified fluid. In the humidifier 36, a back pressure valve 42 is disposed on the discharge side of the off gas supplied through the off gas supply pipe 40.

  The fuel gas supply mechanism 20 includes a fuel gas tank (fuel tank) 44 in which hydrogen gas is stored as fuel gas. One end of a fuel gas pipe 45 is connected to the fuel gas tank 44, and a fuel gas supply pipe 51 is connected to the fuel gas pipe 45 via a shut-off valve 46, a regulator 48 and an ejector 50, and the fuel gas supply A pipe 51 is connected to the fuel cell stack 10.

  An exhaust fuel gas pipe 52 through which used fuel gas is discharged is connected to the fuel cell stack 10 via a water collection tank (water collection mechanism) 53. The exhaust fuel gas pipe 52 is connected to the ejector 50 via a return pipe 54 to constitute a fuel gas circulation system (reactive gas circulation system), and a part thereof communicates with the purge valve 56.

  In the fuel cell stack 10, a plurality of power generation cells 60 are stacked in a horizontal direction (in the direction of arrow A in FIGS. 2 and 3) which is the vehicle length direction, and terminal plates are not shown at both ends in the stacking direction. Further, metal end plates 62a and 62b are disposed through the insulating plate (see FIG. 1). Electric power extraction terminals 63a and 63b protrude outward from the end plates 62a and 62b in the stacking direction, and the electric power extraction terminals 63a and 63b are connected to a vehicle driving motor and auxiliary equipment (not shown).

  As shown in FIG. 2, each power generation cell 60 includes an electrolyte membrane / electrode structure (electrolyte / electrode structure) 66 and first and second separators 68, 70 sandwiching the electrolyte membrane / electrode structure 66. And configured vertically. In addition, the 1st and 2nd separators 68 and 70 are comprised with a carbon separator or a metal separator.

  One end edge (upper end edge) of the power generation cell 60 in the long side direction (arrow C direction) communicates with each other in the arrow A direction to supply an oxidant gas, for example, an oxygen-containing gas. A supply communication hole 72a and a fuel gas supply communication hole 76a for supplying a fuel gas, for example, a hydrogen-containing gas, are provided.

  The other end edge (lower end edge) in the long side direction of the power generation cell 60 communicates with each other in the direction of arrow A, and oxidant gas discharge communication holes (reactive gas discharge communication holes) for discharging the oxidant gas. 72b and a fuel gas discharge communication hole (reaction gas discharge communication hole) 76b for discharging the fuel gas are provided.

  A cooling medium supply communication hole 74a for supplying a cooling medium is provided at one end edge of the power generation cell 60 in the short side direction (arrow B direction), and the other end edge of the power generation cell 60 in the short side direction. Is provided with a cooling medium discharge communication hole 74b for discharging the cooling medium. The cooling medium supply communication hole 74a and the cooling medium discharge communication hole 74b are set in a vertically long shape.

  The electrolyte membrane / electrode structure 66 includes, for example, a solid polymer electrolyte membrane 78 in which a thin film of perfluorosulfonic acid is impregnated with water, and an anode side electrode 80 and a cathode side electrode 82 that sandwich the solid polymer electrolyte membrane 78. With.

  A fuel gas flow path 84 that connects the fuel gas supply communication hole 76 a and the fuel gas discharge communication hole 76 b is formed on the surface 68 a of the first separator 68 facing the electrolyte membrane / electrode structure 66. The fuel gas channel 84 is constituted by, for example, a groove extending in the direction of arrow C. A cooling medium flow path 86 that connects the cooling medium supply communication hole 74 a and the cooling medium discharge communication hole 74 b is formed on the surface 68 b opposite to the surface 68 a of the first separator 68.

  The surface 70a of the second separator 70 facing the electrolyte membrane / electrode structure 66 is provided with, for example, an oxidant gas flow path 88 formed of a groove extending in the direction of arrow C. The oxidant gas supply communication hole 72a and the oxidant gas discharge communication hole 72b communicate with each other. A cooling medium flow path 86 is integrally formed on the surface 70b opposite to the surface 70a of the second separator 70 so as to overlap the surface 68b of the first separator 68. Although not shown, the first and second separators 68 and 70 are provided with seal members as necessary.

  As shown in FIG. 3, the fuel cell stack 10 includes a casing 89 having end plates 62a and 62b as end plates, for example. Instead of the casing 89, the end plates 62a and 62b may be connected by a tie rod (not shown).

  As shown in FIG. 1, the end plate 62a is provided with a cooling medium inlet manifold 96a and a cooling medium outlet manifold 96b. The cooling medium inlet manifold 96a communicates with the cooling medium supply communication hole 74a, while the cooling medium outlet manifold 96b communicates with the cooling medium discharge communication hole 74b. The cooling medium inlet manifold 96 a and the cooling medium outlet manifold 96 b communicate with the radiator 24 through the cooling medium supply pipe 28 and the cooling medium discharge pipe 30.

  As shown in FIG. 3, the end plate 62b has an oxidant gas inlet manifold 98a communicating with the oxidant gas supply communication hole 72a, a fuel gas inlet manifold 100a communicating with the fuel gas supply communication hole 76a, and an oxidant gas discharge communication. An oxidant gas outlet manifold 98b that communicates with the hole 72b and a fuel gas outlet manifold 100b that communicates with the fuel gas discharge communication hole 76b are provided.

  As shown in FIG. 4, the humidifier 36 is fixed to the end plate 62 b of the fuel cell stack 10. The casing of the humidifier 36 is, for example, cast and a plurality of bolts 108 are inserted into the flange portion 106 that is in contact with the end plate 62b. When the bolt 108 is screwed into the end plate 62b, the humidifier 36 is directly fixed to the end plate 62b.

  In the humidifier 36, the first and second humidifying units 110a and 110b are accommodated in a vertical arrangement. The first humidifying unit 110 a and the second humidifying unit 110 b are connected to the air supply pipe 34 and the humidified air supply pipe 38. For example, a hollow fiber membrane humidification structure can be adopted for the first humidifying part 110a and the second humidifying part 110b. The humidifier 36 is integrated with each auxiliary machine constituting the fuel gas supply mechanism 20, for example, a shutoff valve 46, a regulator 48, an ejector 50, and a back pressure valve 42.

  As shown in FIGS. 3, 5 and 6, an outlet pipe 120 is connected to the fuel gas outlet manifold 100b, and a tip 120a of the outlet pipe 120 projects outward from the end plate 62b. The outlet pipe 120 is made of an electrically insulating material (for example, a resin material) or a metal member having an inner surface coated with a resin coat, and a leading end 120a is inserted into the chamber 122 of the water collection tank 53 (FIG. 5 and FIG. (See FIG. 6).

  As shown in FIG. 6, the water surface 124 at the highest water level stored in the chamber 122 of the water collection tank 53 is set to be separated by a distance h below the lower portion of the tip 120 a of the outlet pipe 120. . A drain pipe 126 for discharging the water in the chamber 122 to the outside is provided at the lower portion of the water collection tank 53.

  The operation of the fuel cell system 12 configured as described above will be described below.

  First, as shown in FIG. 1, the air pump 32 constituting the oxidant gas supply mechanism 18 is driven, and external air that is an oxidant gas is sucked and introduced into the air supply pipe 34. This air is introduced into the humidifier 36 from the air supply pipe 34 and supplied to the humidified air supply pipe 38 through the first and second humidifiers 110a and 110b (see FIG. 4).

  At that time, as will be described later, off-gas which is an oxidant gas used for the reaction is supplied to the off-gas supply pipe 40. For this reason, the moisture contained in the off-gas moves to the air before use through a water permeable membrane (not shown) of the humidifier 36, and the air before use is humidified. The humidified air is supplied from the humidified air supply pipe 38 to the oxidant gas supply communication hole 72a in the fuel cell stack 10 through the end plate 62b.

  On the other hand, in the fuel gas supply mechanism 20, the fuel gas (hydrogen gas) in the fuel gas tank 44 is stepped down by the regulator 48 under the opening action of the shutoff valve 46, and then passes through the ejector 50 and ends from the fuel gas supply pipe 51. The fuel gas supply communication hole 76a in the fuel cell stack 10 is introduced through the plate 62b.

  Further, in the cooling medium supply mechanism 16, under the action of the refrigerant pump 26, the cooling medium is introduced from the cooling medium supply pipe 28 through the end plate 62 a to the cooling medium supply communication hole 74 a in the fuel cell stack 10.

  As shown in FIG. 2, the air supplied to the power generation cell 60 in the fuel cell stack 10 is introduced into the oxidant gas flow path 88 of the second separator 70 from the oxidant gas supply communication hole 72a, and the electrolyte membrane / electrode It moves along the cathode side electrode 82 of the structure 66. On the other hand, the fuel gas is introduced into the fuel gas flow path 84 of the first separator 68 from the fuel gas supply communication hole 76 a and moves along the anode side electrode 80 of the electrolyte membrane / electrode structure 66.

  Therefore, in each electrolyte membrane / electrode structure 66, the oxygen in the air supplied to the cathode side electrode 82 and the fuel gas (hydrogen) supplied to the anode side electrode 80 undergo an electrochemical reaction in the electrode catalyst layer. To generate electricity.

  Next, the air consumed by being supplied to the cathode side electrode 82 flows along the oxidant gas discharge communication hole 72b, and is then discharged from the end plate 62b to the off gas supply pipe 40 as an off gas (see FIG. 1).

  Similarly, the fuel gas consumed by being supplied to the anode side electrode 80 is discharged and flows into the fuel gas discharge communication hole 76b, and is discharged from the end plate 62b through the water collecting tank 53 as the discharged fuel gas. It is discharged to the pipe 52 (see FIG. 1). Part of the discharged fuel gas discharged to the discharged fuel gas pipe 52 is returned to the fuel gas supply pipe 51 through the return pipe 54 under the suction action of the ejector 50.

  The discharged fuel gas is mixed with new fuel gas and supplied into the fuel cell stack 10 from the fuel gas supply pipe 51. The remaining discharged fuel gas is discharged under the action of opening the purge valve 56.

  Here, in the anode side electrode 80, the generated water is back-diffused, and this generated water is discharged into the fuel gas discharge communication hole 76b. In the fuel gas discharge communication hole 76b, the generated water introduced to the end plate 62b side is sent to the water collecting tank 53 through the outlet pipe 120 along the flow of the discharged fuel gas. Therefore, the generated water is dropped (dropped) from the front end 120 a of the outlet pipe 120 to the water collecting tank 53 and stored (collected) in the chamber 122 of the water collecting tank 53.

  In this case, in the present embodiment, as shown in FIG. 6, the water surface 124 at the highest water level stored in the chamber 122 is set to be separated from the tip 120 a of the outlet pipe 120 by a distance h. Yes. Thereby, the conductive path by the water in the outlet piping 120 and the water in the water collection tank 53 is interrupted, and it is possible to satisfactorily prevent the occurrence of a liquid junction with a simple and compact configuration. can get.

  As shown in FIG. 2, the cooling medium is introduced into the cooling medium flow path 86 between the first and second separators 68 and 70 from the cooling medium supply communication hole 74 a and then flows along the arrow B direction. . After cooling the electrolyte membrane / electrode structure 66, the cooling medium moves through the cooling medium discharge communication hole 74b and is discharged from the cooling medium outlet manifold 96b of the end plate 62a to the cooling medium discharge pipe 30. As shown in FIG. 1, the cooling medium is cooled by the radiator 24 and then supplied from the cooling medium supply pipe 28 to the fuel cell stack 10 under the action of the refrigerant pump 26.

  In the present embodiment, the water collection tank 53 is provided in the exhaust fuel gas pipe 52 in order to remove the water discharged from the fuel gas discharge communication hole 76b. However, the present invention is not limited to this. For example, in order to remove moisture discharged from the oxidant gas discharge communication hole 72b, the off-gas supply pipe 40 can also be provided with a water collection tank 53.

  Further, high-purity oxygen gas is used as the oxidant gas, and an oxygen gas circulation system (reactive gas circulation system) is formed in the same manner as the fuel gas circulation system described above, and the water collection tank 53 is provided in this oxygen gas circulation system. May be provided.

1 is a schematic configuration diagram of a fuel cell system incorporating a fuel cell stack according to an embodiment of the present invention. It is a disassembled perspective explanatory drawing of the electric power generation cell which comprises the said fuel cell stack. It is a perspective explanatory view from the humidifier side of the fuel cell stack. It is a perspective view of the humidifier and the fuel cell stack. It is a schematic perspective explanatory drawing of the outlet piping and water collection tank which comprise the said fuel cell stack. It is a section explanatory view of the outlet piping and the water collection tank. 1 is a schematic explanatory diagram of a fuel cell system disclosed in Patent Document 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Fuel cell stack 12 ... Fuel cell system 16 ... Coolant supply mechanism 18 ... Oxidant gas supply mechanism 20 ... Fuel gas supply mechanism 24 ... Radiators 26, 32 ... Pump 28 ... Coolant supply pipe 30 ... Coolant discharge pipe 34 ... Air supply pipe 36 ... Humidifier 38 ... Humidified air supply pipe 40 ... Off gas supply pipe 44 ... Fuel gas tank 51 ... Fuel gas supply pipe 52 ... Exhaust fuel gas pipe 53 ... Water collection tank 54 ... Return pipe 60 ... Power generation cell 62a 62b ... End plate 66 ... Electrolyte membrane / electrode structure 68, 70 ... Separator 72a ... Oxidant gas supply communication hole 72b ... Oxidant gas discharge communication hole 74a ... Cooling medium supply communication hole 74b ... Cooling medium discharge communication hole 76a ... Fuel gas supply communication hole 76b ... Fuel gas discharge communication hole 78 ... Solid polymer electrolyte membrane 80 ... Anode side Electrode 82 ... Cathode side electrode 84 ... Fuel gas flow path 86 ... Cooling medium flow path 88 ... Oxidant gas flow path 96a ... Cooling medium inlet manifold 96b ... Cooling medium outlet manifold 98a ... Oxidant gas inlet manifold 98b ... Oxidant gas outlet Manifold 100a ... Fuel gas inlet manifold 100b ... Fuel gas outlet manifold 120 ... Outlet piping 120a ... Tip 122 ... Chamber

Claims (2)

A plurality of power generation cells are stacked, provided with a reaction gas supply communication hole and a reaction gas discharge communication hole for circulating the reaction gas used in the power generation reaction in the stacking direction, and an end plate disposed at one end in the stacking direction. Is a fuel cell stack in which a reaction gas outlet communicating with the reaction gas discharge communication hole is opened,
An outlet pipe connected to the reaction gas outlet and having a tip protruding outward from the end plate;
A water collecting mechanism that collects moisture contained in the reaction gas discharged from the tip of the outlet pipe, and is arranged so that a water surface is positioned below the tip of the outlet pipe;
A fuel cell stack comprising: The fuel cell stack according to claim 1, further comprising a reactive gas circulation system for circulatingly supplying the reactive gas discharged from the reactive gas outlet to the reactive gas supply passage.
The fuel cell stack, wherein the water collection mechanism is disposed in the reaction gas circulation system.

Images