JP2009064619A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent or suppress blockage of a gas passage caused by residence of condensed water. <P>SOLUTION: A fuel gas supply pipe 46a is communicated with a fuel gas supply manifold 24a on at least a lower portion in the vertical direction than a lower end portion of a fuel gas introduction part 24c, and a condensed water recovery pipe 54a is installed on at least a lower portion in the vertical direction than a lower end portion of the fuel gas introduction part 24c. The condensed water recovered in a condensed water recovery tank 56a through the condensed water recovery pipe 54a can be reused as reformer water or the like. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel cell system.

  An outline of a configuration of a general unit cell (also referred to as a fuel cell unit cell) corresponding to the minimum unit of the fuel cell, in particular, a main part including an electrode portion will be described. As illustrated in FIG. 10, a cathode catalyst layer 12 (also referred to as an oxidation electrode or a cathode electrode) and an anode catalyst layer 14 (also referred to as a fuel electrode or an anode electrode) are provided so as to face each other with the electrolyte membrane 10 interposed therebetween. A so-called membrane electrode assembly (MEA) 30 is configured. A cathode diffusion layer 16 is provided outside the cathode catalyst layer 12, and an anode diffusion layer 18 is provided outside the anode catalyst layer 14. Further, a cathode-side separator 26 in which an oxidizing gas flow path 20 and a cell refrigerant flow path 22 are formed is formed outside the cathode diffusion layer 16, and a fuel gas flow path 24 and a cell refrigerant flow are formed outside the anode diffusion layer 18. Anode separators 28 with passages 22 formed therein are provided, and these are integrated by, for example, adhesion or pressure bonding to form a single cell 40. A fuel cell including a cell stack in which a plurality of obtained single cells 40 are stacked so as to obtain a desired electromotive force is applied in various fields.

  During power generation of the fuel cell, the raw material (fuel gas) supplied to the fuel electrode via the fuel gas flow path is hydrogen gas, and the raw material (oxidation gas) supplied to the oxidation electrode via the oxidizing gas flow path is air In this case, hydrogen ions and electrons are generated from the hydrogen gas at the fuel electrode. Electrons reach the oxidation electrode from an external terminal through an external circuit. In the oxidation electrode, water is generated by oxygen in the supplied air, hydrogen ions that have passed through the electrolyte membrane, and electrons that have reached the oxidation electrode through an external circuit. In this way, an electrochemical reaction occurs at the fuel electrode and the oxidation electrode facing each other through the electrolyte membrane, and functions as a battery. This fuel cell has various studies as a clean energy source because it has abundant raw material gas and liquid fuel used for power generation, and because of the principle of power generation, the discharged substance is water. Has been.

  In general, such a fuel cell generates heat associated with a chemical reaction during power generation. However, in order to maintain stable power generation, it is necessary to control the temperature to be within a predetermined temperature range of, for example, about 60 ° C to 100 ° C. Therefore, a cooling medium (refrigerant) such as water or ethylene glycol is circulated through the cell refrigerant flow path 22 provided in each single cell to prevent overheating of the fuel cell.

  In general, in order for a fuel cell to generate electric power satisfactorily, a predetermined amount of water (water content) is maintained with respect to the electrolyte membrane 10 in which, for example, a fluorine-based ion exchange resin such as perfluoro-based or perfluorosulfonic acid is used. Thus, it is preferable to exhibit the function as a proton permeable membrane. For example, moisture adjustment of the electrolyte membrane 10 is performed by humidifying one or both of the reaction gases supplied into the fuel cell.

  By the way, when the supply of moisture to the fuel cell exceeds a predetermined amount, the moisture in the gas is condensed in the gas flow path to generate liquid water (this is referred to as condensed water). If this condensed water blocks the gas flow path and the diffusion layer, a so-called flooding phenomenon occurs in which the source gas necessary for the reaction (also called the reaction gas) is insufficiently supplied to the catalyst layer. However, not only the power generation efficiency is lowered, but the operation state becomes unstable, and in some cases, the system may be stopped. In addition, the gas flow path in which the oxidizing gas circulates on the oxidation electrode side contains not only condensed water derived from gas but also water produced by the reaction between protons and oxygen. Special attention must be paid to the control.

  On the other hand, in addition to the amount of water contained in the gas, the temperature conditions are closely related to the generation of condensed water. In other words, during operation of the fuel cell, the saturated water vapor pressure increases as the temperature rises and the amount of water that can be contained in the gas is large, so the amount of water that condenses is small. For example, when the output is reduced or when the operation is stopped, condensed water is likely to be generated, but the flow rate and / or flow rate of the gas is low. I can't expect it. For this reason, for example, when condensed water is prominent during high humidification operation, for example, immediately after startup, or when the inside of the battery is at a relatively low temperature, such as at low output with a slow gas flow rate, There is a particular concern about the emissions.

  Regarding discharge of condensed water, for example, fuel cell systems as disclosed in Patent Documents 1 to 3 have been proposed.

  Patent Document 1 describes a fuel cell system that is provided with a water reservoir portion for temporarily condensing condensed water or generated water, and capable of discharging the accumulated water by opening an electromagnetic valve.

  Patent Document 2 describes a fuel cell stack capable of easily discharging moisture condensed in a gas supply manifold by inclining by a predetermined angle.

  Patent Document 3 describes a fuel cell in which a partition member for preventing intrusion of condensed water into a single cell is provided in a reaction gas supply manifold.

JP 2003-177871 A JP 2004-207106 A JP 2007-87742 A

  However, in the fuel cell described in Patent Document 3, the configuration in the manifold becomes complicated, which easily leads to an increase in cost. Also, under conditions where a large amount of water can condense, for example, when stopping from a high humidification operation, the condensed water once stored may flow into the gas flow path in the single cell beyond the partition member. is there.

  An object of the present invention is to suppress or prevent blockage of a gas flow path due to retention of condensed water.

  The configuration of the present invention is as follows.

  (1) A cell stack formed by stacking a plurality of unit cells each including a membrane electrode assembly in which both surfaces of an electrolyte membrane are sandwiched between a fuel electrode and an oxidation electrode, and a reaction gas used for power generation in the unit cell. A reaction gas source for supplying to the cell; a reaction gas supply path for supplying the reaction gas derived from the reaction gas source to the cell stack; and the reaction gas supply path that passes through each of the single cells. A reaction gas supply manifold for supplying the reaction gas flowing through the cell stack to the inside of the cell stack, and an introduction section for distributing and introducing the reaction gas supplied to the reaction gas supply manifold to each of the single cells. A reaction gas flow path for flowing the reaction gas introduced from the introduction portion to the electrode portion, and communicated with the reaction gas supply manifold or the reaction gas supply path A condensed water discharge path for discharging condensed water condensed with water in the reaction gas to the outside of the cell stack, and the reaction gas supply path is a lower end portion of the introduction portion with respect to the reaction gas supply manifold. The fuel cell system further communicates at least in a lower part in the vertical direction, and the condensed water discharge path is disposed at least in a lower part in the vertical direction than a lower end part of the introduction part.

  (2) The fuel cell system according to (1), wherein the condensed water discharge passage is in communication with the reaction gas supply manifold.

  (3) The fuel cell system according to the above (1), wherein the condensed water discharge path is connected to a bottom surface portion of the reaction gas supply path.

  (4) The fuel cell system according to (2), wherein the condensed water discharge passage communicates with a lower end portion in a vertical direction of the reaction gas supply manifold.

  (5) The fuel cell system according to any one of (1) to (4), wherein the introduction portion communicates with an upper end portion in a vertical direction of the reaction gas supply manifold.

  (6) The fuel cell system according to any one of (1) to (5), further including a condensed water recovery tank that recovers and stores the condensed water discharged through the condensed water discharge path. , Fuel cell system.

  (7) In the fuel cell system according to any one of (1) to (6), the reaction gas supply manifold has a vertically long shape having a vertical width larger than a horizontal width in a cell plane. There is a fuel cell system.

  (8) The fuel cell system according to any one of (1) to (7), wherein the reaction gas is a fuel gas supplied to a fuel electrode side of the electrode portion.

  (9) The fuel cell system according to any one of (1) to (7), wherein the reaction gas is an oxidizing gas supplied to an oxidizing electrode side of the electrode portion.

  According to the present invention, it is possible to suppress or prevent the blockage of the gas flow path due to the retention of condensed moisture.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, in each drawing, the same code | symbol is attached | subjected about the same structure and the description is abbreviate | omitted depending on the case.

  FIG. 1 is a diagram for explaining the outline of the shape of a cell stack constituting the fuel cell system in the embodiment of the present invention. In FIG. 1, the stacking ends of the stacked unit cells 40 are sandwiched by current collector plates (not shown), and the outer sides thereof are sequentially sandwiched by insulating plates and fastening plates 42 and 44 (not shown), and bolts (not shown) are provided from the outside. The cell stack 50 is formed by pressing and holding the whole in the stacking direction by a method such as fastening by using a method. In FIG. 1, pipes 46 and 48 connected to the fastening plate 42 and extending to the outside of the cell stack 50 are a pair of fluid supply / discharge pipes, and details thereof will be described later. In the present embodiment, a polymer electrolyte fuel cell (PEFC) as exemplified in FIG. 10 can be generally applied to the single cell 40 constituting the cell stack 50.

  FIG. 2 is a diagram illustrating an example of the shape of the anode separator, particularly the shape on the fuel gas flow path side, in the single cell 40 constituting the cell stack 50 shown in FIG. The shape of the anode separator 28 shown in FIG. 2 corresponds to the A-A ′ cross section of the single cell 40 shown in FIG. 10 (however, dimensions, detailed shapes, etc. do not necessarily match).

  In the anode side separator 28 shown in FIG. 2, the fluid manifolds of the oxidizing gas supply manifold 20a, the oxidizing gas discharge manifold 20b, the refrigerant supply manifold 22a, the refrigerant discharge manifold 22b, the fuel gas supply manifold 24a, and the fuel gas discharge manifold 24b are formed. Has been. Each of these fluid manifolds is provided so as to penetrate through the anode separator 28 and further through the single cell 40 shown in FIG. 1, and each fluid (oxidizing gas, fuel gas, cooling medium) is mixed with each other. In order not to do so, they communicate individually.

  In FIG. 2, the fuel gas supplied from the outside of the cell stack flows through the fuel gas supply manifold 24a. The fuel gas flowing through the fuel gas supply manifold 24 a is distributed from the fuel gas introduction part 24 c to each single cell and introduced into the fuel gas flow path 24. Hydrogen in the fuel gas introduced into the fuel gas passage 24 passes through with an electrochemical reaction with oxygen in the oxidizing gas introduced into the oxidizing gas passage (not shown) facing through the MEA, The so-called off-gas after passing through the fuel gas flow path 24, in which the required amount of hydrogen has been consumed, is led out to the fuel gas discharge manifold 24b from the fuel gas outlet 24d (see, for example, FIG. 10). Then, the off-gas of the fuel gas derived from the fuel gas deriving unit 24d of each single cell joins at the fuel gas discharge manifold 24b and is discharged to the outside of the cell stack.

  FIG. 3 shows suitable connection locations of the fuel gas distribution pipes 46 and 48 when the cell stack 50 as shown in FIG. 1 is formed by stacking the single cells including the anode side separator 28 shown in FIG. It is a figure explaining.

  In FIG. 3, a pipe (hereinafter referred to as “fuel gas supply pipe”) used as an anode-side reaction gas supply path (not shown) corresponds to the lower end portion in the vertical direction of the fuel gas supply manifold 24 a indicated by an enclosure 32. The fuel gas is supplied from a fuel gas source (not shown). For example, when the fuel gas before being supplied to the fuel cell is humidified using a humidifier, or when the fuel gas reformed by the reformer (reformed gas) contains moisture used for the reforming reaction In the case where the fuel gas supplied to the fuel gas supply manifold 24a contains moisture, for example, immediately after the start of operation or when the fuel gas is supplied, the water becomes excessive due to the temperature drop of the cell stack, and the condensed water stays in the fuel gas supply manifold 24a. I tend to. In the present embodiment, the fuel gas supply stayed in the fuel gas supply manifold 24a by communicating the fuel gas supply pipe and the fuel gas supply manifold 24a at least in the vertically lower part from the lower end portion of the fuel gas introduction portion 24c. Since it becomes difficult for the condensed water derived from the water contained in the fuel gas supplied from the pipe to flow into the fuel gas passage 24, flooding in the fuel gas passage 24 accompanying the inflow of the condensed water is prevented. It becomes possible to prevent or suppress.

  In the present embodiment, the shape of the fuel gas supply manifold 24a is not limited and may be any shape, but is preferably compared with the width in the horizontal direction (x direction) in the cell plane as shown in FIG. Thus, it has a vertically long shape with a large width in the vertical direction (y direction). According to the present embodiment, it is possible to further increase the vertical height difference between the fuel gas supply pipe and the fuel gas introduction portion 24c, so that the amount of condensed water in the fuel gas supply manifold 24a is large. However, the fuel gas flow path can be secured more reliably. Further, according to the present embodiment, for example, when a fuel cell system including a cell stack is mounted on a moving body such as a vehicle, even when the cell stack is tilted while traveling on a slope, the fuel gas introduction unit 24c Since it becomes possible to suppress inflow of condensed water, it is suitable. In order to maximize the difference in vertical height between the fuel gas supply pipe and the fuel gas introduction part 24c, as shown in FIG. 3, the fuel gas introduction part 24c is connected to the upper end in the vertical direction of the fuel gas supply manifold 24a. It is preferable that the fuel gas supply pipe is connected to the lower end portion in the vertical direction of the fuel gas supply manifold 24a while being arranged so as to communicate with the portion.

  Unless otherwise specified, the terms “horizontal direction” and “vertical direction” refer to the x direction / y direction shown in FIG. 3, and the “upper end”, “lower end”, “ The reference of expression such as “top” and “bottom” is “vertical direction” shown in FIG.

  In another embodiment of the present invention, the fuel gas discharge pipe that discharges the off-gas of the fuel gas is the lower end portion in the vertical direction of the fuel gas discharge manifold 24b indicated by an enclosure 34 or a pipe or fastening corresponding thereto. Connected to a plate (see FIG. 1), the fuel gas off-gas is discharged to the outside. In the present embodiment, the shape of the fuel gas discharge manifold 24b is not limited and may be any shape. Preferably, however, the vertical direction is larger than the horizontal width in the cell plane as shown in FIG. This is a vertically long shape with a large width. According to the present embodiment, the vertical height (width) of the fuel gas outlet 24d can be increased, and even if the amount of condensed water in the fuel gas discharge manifold 24b is large, the fuel gas flow path, particularly It is possible to secure more space in the fuel gas outlet 24d where the condensed water does not stay. For this reason, in general, the off-gas of the fuel gas is more reliably supplied on the downstream side where the flow rate and / or flow velocity tends to be lower than the upstream side of the fuel gas channel 24 containing a large amount of hydrogen gas. It becomes possible to discharge to the outside.

  FIG. 4 is a diagram for explaining the outline of the configuration of the fluid flow path in the fuel cell system according to the embodiment of the present invention, particularly on the anode side. In FIG. 4, a pipe 54a (also referred to as a condensed water discharge pipe) as a condensed water discharge path is connected to the bottom surface portion of the fuel gas supply pipe 46a communicating with the lower end portion of the fuel gas supply manifold 24a. The condensate water recovery tank 56a can be communicated with each other via 58a.

  In FIG. 4, the fuel gas generated by the fuel gas source 52 such as a reformer or a hydrogen cylinder is humidified so as to have a desired water content using a humidifier (not shown) as necessary. Thereafter, the fuel gas is supplied to the lower end portion of the fuel gas supply manifold 24a through the fuel gas supply pipe 46a at a desired flow rate and / or flow rate. Thereafter, the fuel gas is discharged to the outside of the cell stack as off-gas from a fuel gas discharge pipe 48a provided at the lower end portion of the fuel gas discharge manifold 24b via a fuel gas flow path 24 provided in each single cell. . As another embodiment, the fuel gas discharge manifold 24b extends further downward from the lower end portion of the lead-out portion 24d for leading the fuel gas off-gas from the fuel gas flow path 24 to the fuel gas discharge manifold 24b. The fuel gas discharge pipe 48a may be disposed below the lower end portion 24d.

  In FIG. 4, the condensed water condensed at or near the fuel gas supply manifold 24a gradually accumulates at the bottom of the fuel gas supply manifold 24a, and eventually communicates with the lower end portion of the fuel gas supply manifold 24a when it exceeds a predetermined amount. It flows into the condensed water discharge pipe 54a via the fuel gas supply pipe 46a and is stored. In the embodiment, the valve 58a is normally closed, and the condensed water flowing into the condensed water discharge pipe 54a stays in the upper part of the valve 58a. For example, the condensed water stays in the upper part of the valve 58a. When the water reaches a predetermined amount or every time a predetermined time has elapsed, the valve 58a can be opened, and the condensed water can be recovered and stored in the condensed water recovery tank 56a. The condensed water stored in the condensed water recovery tank 56a can be reused as, for example, reformed water in a reformer or humidifying moisture in a humidifier after ion exchange is performed as necessary. The valve 58a may be an open / close type or a variable flow rate type, and any type such as an electromagnetic valve or a float valve can be used. For example, a float valve can be used to open and close the valve. Is preferable because it does not involve power consumption. In the present embodiment, the condensed water flowing through the condensed water discharge pipe 54a and discharged from the single cell is once recovered in the condensed water recovery tank 56a. Also called “condensate recovery pipe”.

  In FIG. 4, the condensed water discharge pipe or the condensed water recovery pipe 54a can be manufactured using the same material as the fuel gas supply pipe 46a, and examples thereof include a stainless steel material (SUS material). However, the present invention is not limited to this. Further, the condensate water recovery pipe 54a and the fuel gas supply pipe 46a can be connected by using an appropriate method according to the material to be applied. Connection by applying a joint member, bonding with an appropriate adhesive, welding, or any other method may be used.

  In the present embodiment, if necessary, it is also preferable to provide an inclination for inducing the inflow of condensed water from the fuel gas supply pipe 46a and / or the fuel gas supply manifold 24a toward the condensed water recovery pipe 54a. is there. Further, at least part of the inner surface of the fuel gas supply pipe 46a and / or the condensed water recovery pipe 54a is hydrophilic so that the water content in the reaction gas is not saturated and does not flow into the cell stack and is appropriately condensed. Treatment and / or hydrophobic treatment may be performed, and further roughening treatment may be performed. Note that the inclination of the slope that induces the inflow of condensed water and the degree of the inner surface treatment of the fuel gas supply pipe 46a and / or the condensed water recovery pipe 54a are determined depending on the fuel gas supply manifold 24a and / or the fuel gas supply pipe 46a, and the anode side. It is possible to set appropriately depending on the wettability of the surface of the flow path such as the condensed water recovery pipe 54a and the operating conditions of the fuel cell. Further, the inclination for inducing the inflow of condensed water may have any shape as long as the generated condensed water can be directly or indirectly allowed to flow into the condensed water recovery pipe 54a on the anode side.

  FIG. 5 is a conceptual diagram for explaining the outline of the configuration focusing particularly on the flow of the fluid containing the reaction gas in the fuel cell system having the flow path of the fuel gas shown in FIG. 4 on the anode side.

  In FIG. 5, for example, a reformer can be used as the fuel gas source 52. For example, the fuel gas source 52, which is a reformer, combusts, for example, a fuel gas off-gas using air or the like as an oxygen source and raises the temperature in the apparatus, and natural gas or city gas. A reforming part 52b for reforming a hydrocarbon such as methane contained in the fuel gas raw material to obtain a reformed gas containing hydrogen or carbon monoxide, and reacting carbon monoxide in the reformed gas with water. A shift unit 52c that lowers the carbon monoxide concentration, and a CO removal unit 52d that removes carbon monoxide in the reformed gas that becomes a catalyst poison and obtains fuel gas to be supplied into the cell stack. it can. If necessary, it is also suitable to remove sulfur components contained in the fuel gas raw material using a desulfurizer (not shown).

  The fuel gas containing hydrogen obtained from the fuel gas source 52 is humidified as necessary, and is supplied to the cell stack 50 through the fuel gas supply pipe 46a. On the other hand, an oxidizing gas such as air or pure oxygen is supplied to the cell stack 50 via the oxidizing gas supply pipe 46c. The hydrogen in the fuel gas supplied to the cell stack 50 and the oxygen in the oxidizing gas are subjected to a reaction through the electrolyte membrane at the fuel electrode and the oxidizing electrode in each unit cell, while each off gas is a fuel gas. The exhaust pipe 48a and the oxidizing gas exhaust pipe 48c are exhausted to the outside of the cell stack 50 (see, for example, FIG. 10).

  In the present embodiment, a condensed water recovery pipe 54a is connected to the fuel gas supply pipe 46a at or near the connection portion with the cell stack 50, and stays at the bottom of the fuel gas supply manifold (not shown in FIG. 5). It has a configuration capable of flowing in and storing condensed water. According to this configuration, the long-term retention of condensed water in the fuel gas supply manifold and the fuel gas flow path provided in each single cell, or the occurrence of a malfunction of the fuel gas source 52 due to the reverse flow of the condensed water, etc. It becomes possible to prevent or suppress.

  Further, in the present embodiment, the condensed water stored in the condensed water recovery tank 56a flows from the condensed water recovery pipe 54a into the condensed water recovery tank 56a by the operation of the valve 58a. For example, when a reformer is used as the fuel gas source 52, it can be supplied to the reforming section 52b as reforming water and reused. At this time, in the condensed water recovery pipe 54a and / or the condensed water supply pipe 60, if necessary, a filter for removing foreign matters mixed in the condensed water or an ion exchange membrane for removing water-soluble impurities such as metal ions. Alternatively, it is also preferable to apply an ion exchange resin or the like.

  In FIG. 5, the cooling medium supplied from the refrigerant supply pipe 46b to the inside of the cell stack 50 via a refrigerant supply manifold (not shown) flows through a cell refrigerant flow path (not shown) between the single cells, and the cells are exchanged by heat exchange. After the stack 50 is cooled, the stack 50 is discharged to the outside of the cell stack 50 through a refrigerant discharge pipe 48b communicating with a refrigerant discharge manifold (not shown). The circulation of the cooling medium may be by application of tap water or the like, or may be a circulation type by application of a cooler (not shown), and is not particularly limited. In the case of mounting, it is preferable to use a circulation type refrigerant flow path.

  FIG. 6 is a diagram for explaining the outline of the configuration of the fluid flow path in the fuel cell system according to another embodiment of the present invention, particularly on the cathode side. The shape of the cathode-side separator 26 shown in FIG. 6 corresponds to the B-B ′ cross-sectional view of the single cell 40 shown in FIG. 10 (however, the dimensions, detailed shape, etc. do not necessarily match).

  The cathode side separator 26 shown in FIG. 6 is formed with respective fluid manifolds of an oxidizing gas supply manifold 20a, an oxidizing gas discharge manifold 20b, a refrigerant supply manifold 22a, a refrigerant discharge manifold 22b, a fuel gas supply manifold 24a, and a fuel gas discharge manifold 24b. Has been. Each of these fluid manifolds is provided so as to pass through the cathode side separator 26 and further pass through a single cell (not shown), and communicate with each other individually so that the fluids do not mix with each other.

  In FIG. 6, a condensed water recovery pipe 54c is connected to a bottom face portion of a pipe 46c (hereinafter referred to as “oxidizing gas supply pipe”) 46c communicating with the lower end portion of the oxidizing gas supply manifold 20a as a cathode side reaction gas supply path. It is configured to be able to communicate with the condensed water recovery tank 56c through the valve 58c.

  In FIG. 6, after the oxidizing gas source 53 including an air pump or a blower is used to humidify the derived oxidizing gas such as air or oxygen to a desired moisture content using the humidifier 64. Then, the gas flows through the oxidizing gas supply pipe 46c and is supplied to the lower end portion of the oxidizing gas supply manifold 20a at a desired flow rate and / or flow rate. Thereafter, the oxidizing gas is discharged to the outside of the cell stack 50 as an off-gas from the oxidizing gas discharge pipe 48c provided at the lower end portion of the oxidizing gas discharge manifold 20b via the oxidizing gas flow path 20 provided in each single cell. The

  In FIG. 6, the condensed water condensed at or near the oxidizing gas supply manifold 20a gradually accumulates at the bottom of the oxidizing gas supply manifold 20a, and eventually communicates with the lower end portion of the oxidizing gas supply manifold 20a when a predetermined amount is exceeded. It flows into the condensed water recovery pipe 54c via the oxidizing gas supply pipe 46c and is stored. In the embodiment, the valve 58c is normally closed, and the condensed water flowing into the condensed water recovery pipe 54c stays at the upper part of the valve 58c. For example, the condensed water stays at the upper part of the valve 58c. When the amount of water reaches a predetermined amount or every time a predetermined time elapses, the valve 58c is released, and the condensed water can be stored and recovered in the condensed water recovery tank 56c. The condensed water recovered in the condensed water recovery tank 56c can be reused as, for example, reformed water in a reformer or a humidifying moisture supply source in a humidifier after ion exchange is performed as necessary. In the present embodiment, the valve 58c may be the same as or different from the valve 58a shown in FIG.

  On the other hand, in FIG. 6, the oxidizing gas discharge pipe 48c for discharging the oxidizing gas off-gas to the outside of the cell stack 50 is preferably communicated with the lower end portion of the oxidizing gas discharge manifold 20b. According to the present embodiment, it is possible to prevent or suppress excessive stagnation of the condensed water containing the generated water contained in the oxidizing gas off-gas in the oxidizing gas discharge manifold 20b, and appropriately drain the water appropriately. The gas flow path can be secured, which is preferable.

  Further, in the present embodiment, the oxidizing gas exhaust pipe 48c is provided in the humidifier 64, for example, an oxidizing gas off-gas having a high moisture content and / or temperature, and an oxidizing gas having a relatively low moisture content and / or temperature. It can be set as the structure which carries out humidity exchange and / or temperature exchange between (for supply). In general, the off gas of the oxidizing gas discharged to the oxidizing gas discharge manifold 20b includes moisture derived from the generated water generated by the electrode reaction in addition to the moisture humidified by the humidifier 64. Further, the oxidizing gas off-gas discharged from the operating cell stack 50 is generally at a higher temperature than the oxidizing gas before the cell stack 50 is supplied. According to the present embodiment, it is possible to reuse at least part of the moisture and / or waste heat contained in a large amount in the off-gas in the oxidizing gas by exchanging it with the oxidizing gas before supplying the cell stack 50. Become.

  FIG. 7 is a conceptual diagram for explaining the outline of the configuration focusing particularly on the flow of the fluid containing the reaction gas in the fuel cell system having the flow path of the oxidizing gas shown in FIG. 6 on the cathode side. The fuel cell system shown in FIG. 7 has the same configuration as the fuel cell system shown in FIG. 5 except for the oxidizing gas flow path on the cathode side.

  In FIG. 7, the oxidizing gas containing oxygen that has been humidified by passing through the humidifier 64 from an oxidizing gas source (not shown) is supplied to the cell stack 50 via the oxidizing gas supply pipe 46c. In the MEA in each unit cell, oxygen in the oxidizing gas and hydrogen in the fuel gas supplied through the fuel gas supply pipe 46a are opposed to each other through the electrolyte membrane in each unit cell. It reacts with the fuel electrode (see, for example, FIG. 10), and the off-gas of each reaction gas is discharged to the outside of the cell stack 50 from the oxidizing gas discharge pipe 48c and the fuel gas discharge pipe 48a.

  In FIG. 7, a condensed water recovery pipe 54c is connected to or near the communicating portion of the oxidizing gas supply pipe 46c with the cell stack 50. At the bottom of the oxidizing gas supply manifold not shown in FIG. The condensate that stays can be discharged to the outside of the cell stack 50. According to this configuration, the trouble of an oxidizing gas source (not shown here) due to long-term residence of condensed water in the oxidizing gas supply manifold and in the oxidizing gas flow path provided in each single cell or the reverse flow of condensed water is prevented. Generation or the like can be prevented or suppressed.

  In the present embodiment, the condensed water that is sent from the condensed water recovery pipe 54 c to the condensed water recovery tank 56 by the operation of the valve 58 c and stored is used when the reformer is used as the fuel gas source 52, for example. It is also possible to supply the reforming part 52b as reforming water and reuse it.

  In the present embodiment, the condensed water recovery pipe 54a connected to the fuel gas supply pipe 46a and the condensed water recovery pipe 54c connected to the oxidizing gas supply pipe 46c are both configured to be able to communicate with the condensed water recovery tank 56. The condensed water condensed in the anode side supply unit and the cathode side supply unit is collected in one place and is retained. According to this Embodiment, it becomes possible to suppress the enlargement as the whole system accompanying common use of a member. On the other hand, as another embodiment, the condensed water condensed in the anode side supply unit and the cathode side supply unit may be separately collected and retained. According to the present embodiment, for example, one condensed water is used as reforming water, and the other condensed water is used for humidification. Condensed water can be reused more effectively.

  FIG. 8 is a diagram illustrating an outline of a configuration of a fuel cell system according to still another embodiment of the present invention. In FIG. 8, the anode-side condensed water recovery pipe 54a has a configuration that directly communicates with the fuel gas supply manifold 24a in place of the configuration that is connected to the fuel gas supply pipe 46a that communicates with the fuel gas supply manifold 24a. Except for this, the fuel cell system has substantially the same configuration as that shown in FIG.

  In FIG. 8, the condensed water condensed in the fuel gas supply manifold 24a or in the vicinity thereof flows into the condensed water recovery pipe 54a connected to the lower end portion of the fuel gas supply manifold 24a and is stored therein. In the present embodiment, since the fuel gas supply pipe 46a is disposed independently of the condensed water recovery pipe 54a, the fuel gas supply manifold does not disturb the flow of the fuel gas from the fuel gas supply pipe 46a. The condensed water in 24a can be discharged to the outside of the cell stack, and flooding in the gas flow path can be prevented or suppressed.

  In the present embodiment, it is preferable that the condensed water recovery pipe 54a communicates with the fuel gas supply manifold 24a at least in the lower part in the vertical direction from the lower end part of the fuel gas introduction part 24c. It is more preferable to communicate with the lower part of the vertical direction height of 46a. According to the present embodiment, the condensed water in the fuel gas supply manifold 24a can flow more reliably into the condensed water recovery pipe 54a without flowing into the fuel gas supply pipe 46a.

  In the fuel cell system shown in FIG. 8, the gas channel structure on the anode side has been described, but the same configuration can be applied to the cathode side. FIG. 9 shows an example of the case where the same gas flow path structure is applied to the cathode side of the anode side gas flow path structure shown in FIG.

  The fuel cell system shown in FIG. 9 has the same configuration as the fuel cell system shown in FIG. 7 except for the connection of the condensed water recovery pipes 54a and 54c and the reaction gas supply pipes 46a and 46c to the cell stack 50.

  In FIG. 9, the anode side condensed water recovery pipe 54a communicates with a fuel gas supply manifold (not shown) independently of the fuel gas supply pipe 46a. Similarly, the condensed water recovery pipe 54c on the cathode side communicates with an oxidizing gas supply manifold (not shown) independently of the oxidizing gas supply pipe 46c. According to the present embodiment, it is possible to prevent or suppress the occurrence of flooding due to condensed water condensed in each reactive gas supply manifold and the vicinity thereof, and to perform more stable distribution of the reactive gas.

  According to the embodiment of the present invention and the modification thereof described above, it is possible to prevent or suppress the blockage of the gas flow path accompanying the retention of condensed water condensed in the reaction gas manifold and the vicinity thereof. Further, according to another embodiment of the present invention, condensed water can be collected, stored and reused.

  The present invention is not limited to a stationary fuel cell, and can be suitably used, for example, in a mobile body-mounted fuel cell.

It is a figure explaining the outline of the shape of a cell stack in an embodiment of the invention. In the single cell shown in FIG. 1, it is a figure explaining an example of the shape by the side of the fuel gas flow path of an anode side separator. It is a figure explaining the suitable connection location of piping for fuel gas distribution in the cell stack containing the anode side separator shown in FIG. It is a figure explaining the outline of the structure of the fluid flow path in the fuel cell system in embodiment of this invention, especially the anode side. FIG. 5 is a conceptual diagram illustrating an outline of a configuration in particular focusing on fluid circulation in the fuel cell system having the fuel gas circulation path shown in FIG. 4. It is a figure explaining the outline of the structure of the fluid flow path in the fuel cell system in other embodiment of this invention especially in the cathode side. FIG. 7 is a conceptual diagram illustrating an outline of a configuration in which attention is paid to fluid circulation in the fuel cell system having the oxidizing gas circulation path shown in FIG. 6. It is a figure explaining the outline of a structure of the fuel cell system in another embodiment of this invention. In the fuel cell system in another embodiment of this invention, it is a conceptual diagram explaining the outline of the structure which paid its attention especially to the distribution | circulation of a fluid. It is a schematic diagram which shows the outline of a structure of a general single cell.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Electrolyte membrane, 12 Cathode catalyst layer, 14 Anode catalyst layer, 16 Cathode diffusion layer, 18 Anode diffusion layer, 20 Oxidation gas flow path, 20a Oxidation gas supply manifold, 20b Oxidation gas discharge manifold, 22 Cell refrigerant flow path, 22a Refrigerant Supply manifold, 22b Refrigerant discharge manifold, 24 Fuel gas flow path, 24a Fuel gas supply manifold, 24b Fuel gas discharge manifold, 24c Fuel gas introduction part, 24d Fuel gas outlet part, 26 Cathode side separator, 28 Anode side separator, 30 Membrane Electrode assembly (MEA), 40 single cell, 42, 44 fastening plate, 46, 48 piping, 46a fuel gas supply pipe, 46b refrigerant supply pipe, 46c oxidizing gas supply pipe, 48a fuel gas discharge pipe, 48b refrigerant discharge pipe, 48c Oxidizing gas discharge pipe, 5 Cell stack, 52 Fuel gas source, 52a Combustion section, 52b Reforming section, 52c Shift section, 52d CO removal section, 53 Oxidation gas source, 54a, 54c Condensate recovery pipe (condensate discharge pipe), 56, 56a, 56c Condensed water recovery tank, 58a, 58c valve, 60 condensed water supply pipe, 62 pump, 64 humidifier.

Claims (9)

A cell stack formed by laminating a plurality of unit cells including a membrane electrode assembly in which both surfaces of an electrolyte membrane are sandwiched between a fuel electrode and an oxidation electrode;
A reactive gas source for supplying the single cell with a reactive gas for power generation in the single cell;
A reaction gas supply path for supplying the reaction gas derived from the reaction gas source to the cell stack;
A reaction gas supply manifold that passes through each of the single cells and distributes the reaction gas flowing through the reaction gas supply path into the cell stack;
A reaction gas that has an introduction part that distributes and introduces the reaction gas supplied to the reaction gas supply manifold to each of the single cells, and distributes the reaction gas introduced from the introduction part to the electrode part. A flow path;
A condensed water discharge passage that communicates with the reaction gas supply manifold or the reaction gas supply passage and discharges condensed water in which moisture in the reaction gas is condensed to the outside of the cell stack;
With
The reaction gas supply path communicates with the reaction gas supply manifold at least in a vertically lower portion than a lower end portion of the introduction portion,
The fuel cell system, wherein the condensed water discharge passage is disposed at least in a vertically lower portion from a lower end portion of the introduction portion. The fuel cell system according to claim 1,
The fuel cell system, wherein the condensed water discharge passage communicates with the reaction gas supply manifold. The fuel cell system according to claim 1,
The fuel cell system, wherein the condensed water discharge path is connected to a bottom surface portion of the reaction gas supply path. The fuel cell system according to claim 2, wherein
The fuel cell system, wherein the condensed water discharge passage communicates with a lower end portion in a vertical direction of the reaction gas supply manifold. The fuel cell system according to any one of claims 1 to 4,
The fuel cell system, wherein the introduction portion communicates with an upper end portion in a vertical direction of the reaction gas supply manifold. The fuel cell system according to any one of claims 1 to 5,
A fuel cell system, further comprising a condensed water collection tank for collecting and storing condensed water discharged through the condensed water discharge path. The fuel cell system according to any one of claims 1 to 6,
The fuel gas system according to claim 1, wherein the reaction gas supply manifold has a vertically long shape having a vertical width larger than a horizontal width in a cell plane. The fuel cell system according to any one of claims 1 to 7,
The fuel cell system, wherein the reaction gas is a fuel gas supplied to a fuel electrode side of the electrode portion. The fuel cell system according to any one of claims 1 to 7,
The fuel cell system, wherein the reaction gas is an oxidizing gas supplied to an oxidizing electrode side of the electrode portion.

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