JP2007005176A - Exhaust gas treatment device of fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust gas treatment device of a fuel cell restraining hydrogen exhausted from the fuel cell from being exhausted from a diluting unit all at once to a hydrogen exhaust flow channel. <P>SOLUTION: The exhaust gas treatment device 40 is provided with a hydrogen exhaust flow channel P in which hydrogen exhausted from an anode 12 of the fuel cell 10 flows, a diluting unit 41 connected to the hydrogen exhaust flow channel P and diluting the hydrogen by mixing the exhausted hydrogen with diluted gas. A branch line is provided at the hydrogen exhaust flow channel P at an upstream side of the diluting unit 41, and at the same time, a hydrogen reservoir 43 storing part of the exhausted hydrogen is provided at the branched line. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an exhaust gas treatment apparatus for a fuel cell that dilutes and discharges hydrogen discharged from a fuel cell to the outside.

  In recent years, fuel cells that generate electricity by generating an electrochemical reaction by supplying hydrogen to the anode and oxygen to the cathode have been actively developed. In such a fuel cell, in order to increase the output, more hydrogen than the amount consumed by the anode is often supplied, and unreacted hydrogen that has not been used in the reaction is discharged from the anode. Therefore, in order to increase the utilization efficiency of hydrogen, a technique has been proposed in which a hydrogen circulation system for returning the discharged unreacted hydrogen to the hydrogen supply side and circulating the hydrogen is employed.

  Further, when the fuel cell generates power, water is generated at the cathode, and a part of the generated water permeates through the solid polymer electrolyte membrane (hereinafter, electrolyte membrane) to the anode side. In addition, in order to ensure the wet state of the electrolyte membrane and increase the diffusibility of protons (hydrogen ions) in the electrolyte membrane, for example, gas supplied to the cathode side or anode side of the fuel cell (air containing hydrogen, oxygen, etc.) ) Is used.

  Therefore, in the case of a fuel cell system that employs a hydrogen circulation system, the amount of moisture accompanying the circulating hydrogen increases with power generation on the anode side of the fuel cell, and the power generation efficiency of the fuel cell may decrease. Thus, when the amount of water accompanying the circulating hydrogen becomes high, this is temporarily discharged (this is called hydrogen purging), and the hydrogen purged hydrogen is diluted with a diluter (mixing unit). Thus, a technique for discharging to the outside has been proposed (see, for example, Patent Document 1).

In this fuel cell system, a large amount of hydrogen is blown directly into the hydrogen air mixing container at the time of hydrogen purge, and the anode off gas flows out from the air introduction pipe upstream or downstream of the cathode off gas. A high concentration of hydrogen was mixed in the cathode offgas. Conventionally, in order to prevent the high-concentration hydrogen from being discharged to the outside, pressure loss is provided in the cathode offgas path or a check valve is provided to suppress the backflow of hydrogen.
JP 2002-289237 A (paragraphs 0013 to 0020, FIGS. 2 and 8)

However, the technique described in Patent Document 1 has a problem in that, during the hydrogen purge, the anode off gas containing hydrogen flows into the diluter at a stretch and is discharged to the outside.
In addition, the anode off gas is exhausted while being slowly mixed with the cathode off gas in the mixing chamber after the hydrogen concentration temporarily rises as it is exhausted at the time of the hydrogen purge, so all the hydrogen in the mixing chamber is exhausted. There was a problem that it took time to be done.

  Accordingly, an object of the present invention is to provide an exhaust gas treatment device for a fuel cell in which hydrogen discharged from the fuel cell is prevented from being discharged from the diluter at once into the hydrogen discharge channel.

  As a means for solving the above-described problems, the invention of the exhaust gas treatment device for a fuel cell according to claim 1 includes a hydrogen discharge channel through which hydrogen discharged from the anode of the fuel cell flows, and the hydrogen discharge channel. And a diluter for diluting the hydrogen by mixing the discharged hydrogen and a diluting gas, the exhaust gas processing apparatus for a fuel cell, wherein the hydrogen on the upstream side of the diluter The discharge flow path is provided with a branch line, and a hydrogen reservoir for storing a part of the discharged hydrogen is provided in the branch line.

  According to the fuel cell exhaust gas treatment device of the present invention, the hydrogen discharged from the anode of the fuel cell is provided with a branch line in the hydrogen discharge channel on the upstream side of the diluter. By connecting the hydrogen reservoir, the hydrogen reservoir and the diluter flow separately in the middle of the hydrogen discharge flow path. For this reason, at the time of hydrogen purge, a part of the hydrogen is stored in the hydrogen reservoir, so that the hydrogen flows into the diluter at a stretch and is not discharged to the outside from the hydrogen discharge channel. Since the hydrogen flowing into the diluter is provided with a branch line and a hydrogen reservoir in the hydrogen discharge flow path, the flow rate is decreased and the hydrogen flows slowly, so that the dilution processing efficiency is improved. As a result, high-concentration hydrogen is not discharged from the downstream side of the diluter to the outside, such as in the atmosphere, and the hydrogen fed into the diluter is prevented from flowing backward to the cathode upstream side.

  The invention of a fuel cell exhaust gas treatment device according to claim 2 is the fuel cell exhaust gas treatment device according to claim 1, wherein the outlet of the hydrogen reservoir and the diluter or downstream of the diluter are provided. A hydrogen reservoir outlet channel that connects to the side pipe, and a first one-way valve that is provided in the hydrogen reservoir outlet channel and opens when the pressure on the upstream side is equal to or higher than the first predetermined pressure. Features.

  According to the invention of the exhaust gas treatment device for a fuel cell according to claim 2, hydrogen discharged from the fuel cell is first fed into a diluter or a hydrogen reservoir outlet channel connected to a downstream pipe of the diluter. By providing the directional valve, it is restrained from flowing only from the hydrogen reservoir toward the outlet of the hydrogen reservoir outlet channel. The hydrogen reservoir outlet channel is connected to the diluter or downstream of the diluter, and is provided with a first one-way valve that opens when the upstream pressure is equal to or higher than the first predetermined pressure. Hydrogen is discharged into the dilution channel only when it is introduced into the reservoir and the pressure in the hydrogen reservoir becomes equal to or higher than the first predetermined pressure. For this reason, at the time of hydrogen purging, hydrogen can flow into the dilution flow path all at once, and hydrogen with a high hydrogen concentration can be prevented from being discharged outside from the hydrogen discharge flow path. Further, when the fuel cell is stopped, the hydrogen discharged from the fuel cell can be stored in the hydrogen reservoir by closing the first one-way valve.

  According to a third aspect of the present invention, there is provided an exhaust gas processing apparatus for a fuel cell according to the first or second aspect, wherein the fuel cell exhaust gas processing apparatus is connected to the hydrogen reservoir at the inlet side of the hydrogen reservoir. A second one-way valve that restricts the flow of hydrogen, and the second one-way valve opens when the pressure on the upstream side is equal to or higher than a second predetermined pressure.

  According to the invention of the exhaust gas treatment device for a fuel cell according to claim 3, the hydrogen discharged from the fuel cell is in the second one direction for restricting the flow of hydrogen into the hydrogen reservoir on the inlet side of the hydrogen reservoir. A valve is provided, and the second one-way valve is opened when the upstream pressure is equal to or higher than the second predetermined pressure. As a result, since the hydrogen flowing into the hydrogen reservoir can be stored in a high pressure state lower than the second predetermined pressure, the flow rate of the hydrogen flowing out from the hydrogen reservoir can be adjusted. The flow rate of the discharged hydrogen can be reduced.

  A fuel cell exhaust gas treatment device according to a fourth aspect of the invention is the fuel cell exhaust gas treatment device according to any one of the first to third aspects, wherein the hydrogen discharge flow path is provided. And a branch point between the branch line and the hydrogen reservoir, and a hydrogen reservoir inlet channel for guiding a part of the hydrogen to the hydrogen reservoir is provided, and the orientation of the hydrogen reservoir inlet channel at the branch point is , Along the direction of the hydrogen discharge flow path at the branch point.

  According to the invention of the exhaust gas treatment device for a fuel cell according to claim 4, the flow resistance is reduced because the direction at the branch point of the hydrogen reservoir inlet channel is along the direction of the hydrogen discharge channel at the branch point. Since it becomes small, it comes to flow smoothly in the mainstream direction of the hydrogen discharge channel. As a result, the flow rate of hydrogen flowing through the diluter is regulated and reduced, and the flow rate of hydrogen discharged and directly discharged into the hydrogen reservoir is reduced.

  The fuel cell exhaust gas treatment device according to claim 5 is the fuel cell exhaust gas treatment device according to claim 4, wherein the hydrogen discharge flow path between the branch point and the diluter is provided. The minimum cross-sectional area of is smaller than the minimum cross-sectional area of the hydrogen reservoir inlet channel between the branch point and the hydrogen reservoir.

  According to the invention of the exhaust gas treatment device for a fuel cell according to claim 5, the hydrogen discharged from the fuel cell has a minimum cross-sectional area of the hydrogen discharge flow path between the branch point and the diluter. Since it is smaller than the minimum cross-sectional area of the hydrogen reservoir inlet channel between the hydrogen reservoir and the hydrogen reservoir, it flows more to the reservoir side where the minimum cross-sectional area is larger. As a result, most of the hydrogen discharged from the fuel cell is stored in the hydrogen reservoir, and the flow rate of the hydrogen discharged directly to the outside is reduced, and the flow rate flowing to the diluter is regulated and reduced. It becomes like this. For this reason, at the time of purging, it becomes possible to prevent hydrogen from flowing into the diluter and being discharged to the downstream hydrogen discharge passage at once.

  According to the exhaust gas treatment device for a fuel cell of the present invention, hydrogen discharged from the fuel cell is prevented from being discharged from the diluter at once into the hydrogen discharge channel, and is prevented from flowing backward to the upstream side of the cathode. be able to.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 5.
FIG. 1 is a block diagram showing a configuration of an exhaust gas processing apparatus for a fuel cell according to the present embodiment.

≪Configuration of fuel cell system≫
First, a fuel cell system S including an exhaust gas processing device 40 of a fuel cell 10 according to an embodiment of the present invention will be described with reference to FIG. The fuel cell system S is mounted on, for example, a fuel cell vehicle that travels by rotating a traveling electric motor (traveling motor) with the power generated by the fuel cell 10.
The fuel cell system S includes a fuel cell 10, an anode system 20 that supplies and discharges hydrogen (fuel gas, reaction gas) to and from the anode 12 of the fuel cell 10, and air (oxidant gas, reaction) at the cathode 13 of the fuel cell 10. Gas)), an exhaust gas treatment device 40 for discharging hydrogen discharged from the fuel cell 10 at positions downstream of the anode system 20 and the cathode system 30 to the outside of the fuel cell vehicle, and an ignition switch 52. (Hereinafter, IG) and other devices, and a control unit 60 for controlling them are mainly provided.

<Configuration of fuel cell>
In the fuel cell 10 (fuel cell stack), both surfaces of a monovalent cation exchange type electrolyte membrane 11 are sandwiched between an anode 12 (fuel electrode) and a cathode 13 (air electrode) on which a catalyst (Pt or the like) is supported. A solid polymer electrolyte fuel cell (MEA) comprising a plurality of unit cells each composed of a membrane electrode assembly (MEA: membrane electrode assembly) and a separator sandwiching the MEA. Polymer Electrolyte Fuel Cell (PEFC). When hydrogen is supplied to the anode 12 and humidified air is supplied to the cathode 13, a potential difference is generated in the MEA, and in response to a power request from an external load such as a traveling motor connected to the output terminal of the fuel cell 10, The fuel cell 10 generates power. In addition, each single cell is connected to a control unit 60 and connected to a cell voltage detection monitor (not shown) that detects an output voltage (hereinafter, cell voltage).

<Anode system-Connection of piping on the hydrogen supply side>
The hydrogen supply side of the anode system 20 has a hydrogen tank 21 in which hydrogen is stored toward the downstream side (fuel cell 10 side), a shut-off valve 22 that regulates the outflow of hydrogen from the hydrogen tank 21, and hydrogen. And an ejector 23 for circulating an anode off gas (hydrogen off gas). The hydrogen tank 21 is connected to the shut-off valve 22 via a pipe 21a. The shutoff valve 22 is electrically connected to a control unit 60 described later, and the control unit 60 opens and closes the shutoff valve 22 as appropriate. The shutoff valve 22 is connected to an ejector 23 via a pipe 22a, and the ejector 23 is connected to the anode 12 of the fuel cell 10 via a pipe 23a. Further, a pressure reducing valve (not shown) is provided in the pipe 22a. Therefore, when the control unit 60 opens the shutoff valve 22, hydrogen is depressurized from the hydrogen tank 21 by a pressure reducing valve to be supplied to the anode 12 of the fuel cell 10.

<Anode system-Connection of piping on the hydrogen discharge side>
A hydrogen purge valve 24, a diluter 41, a second reed valve 42, a hydrogen reservoir 43, and a first reed valve 44 are provided on the hydrogen discharge side of the anode system 20. On the hydrogen discharge side of the anode system 20, a hydrogen circulation passage (pipe 24 b) that circulates anode off-gas containing hydrogen discharged from the fuel cell 10 to the ejector 23, and hydrogen discharged from the anode 12 of the fuel cell 10. And a hydrogen discharge passage P for discharging to the outside.
This hydrogen discharge channel P is a hydrogen dilution line (pipe 24d) that is a channel through which the anode off-gas is discharged via the hydrogen purge valve 24 and the diluter 41 at a branch point c downstream of the hydrogen purge valve 24 described later. ) And branch lines (pipes 24 e, 42 a, 43 a, 44 a) that are branched after the anode off gas passes through the hydrogen purge valve 24 and are discharged through the hydrogen reservoir 43. So connected. The branch line is connected to the hydrogen discharge channel P on the upstream side of the diluter 41 and is provided.

  The upstream side of the hydrogen purge valve 24 is connected to the downstream side of the anode 12 of the fuel cell 10 via the pipe 24a, and the anode off gas containing unreacted hydrogen discharged from the anode 12 of the fuel cell 10 is The pipe 24a flows toward the hydrogen purge valve 24. In addition, a pipe 24b for connecting to the ejector 23 is provided at an intermediate position on the downstream side of the pipe 24a to form the hydrogen circulation channel. Furthermore, the hydrogen purge valve 24 is electrically connected to the control unit 60, and the control unit 60 opens and closes the hydrogen purge valve 24 as appropriate. The hydrogen purge valve 24 is connected to a pipe 24c that branches into a pipe 24d and a pipe 24e at a branch point c in the middle of the flow direction of the hydrogen discharge passage P described later.

  The pipe 24d has an upstream end connected to the branch point c, and a downstream end connected to the diluter 41 to form the hydrogen dilution line. The pipe 24e has an upstream end connected to the branch point c, a downstream end connected to the second reed valve 42, and is branched from the pipe 24d. The pipes 24a, 43a and 44a A branch line is formed. The direction of the hydrogen reservoir inlet flow path (pipe 24e, 42a) of the pipe 24e at the branch point c is, for example, the flow direction of the hydrogen discharge flow path P at the branch point c by the T-shaped joint (the main flow of the anode off gas). Is arranged substantially linearly along the flow direction) and is connected to the second reed valve 42 on the hydrogen reservoir inlet channel of the hydrogen reservoir 43.

The second reed valve 42 is connected to the hydrogen reservoir 43 via a pipe 42a.
The hydrogen reservoir 43 is connected to the first reed valve 44 through a pipe 43a. The first reed valve 44 is connected to an exhaust pipe 41a of the diluter 41 by a pipe 44a so as to be discharged to the outside such as in the atmosphere.

More specifically, when the cell voltage of any single cell constituting the fuel cell 10 is low, it is estimated that the amount of water in the anode off gas (that is, the amount of water in the anode 12) is high (at the time of hydrogen purge). ), The control unit 60 opens the hydrogen purge valve 24, and the anode off gas having a high water content is sent to the diluter 41 and the hydrogen reservoir 43 of the exhaust gas processing device 40 through the pipe 24c. Note that the anode off-gas sent to the exhaust gas treatment device 40 during the hydrogen purge includes nitrogen, etc. in addition to hydrogen and moisture.
On the other hand, when the cell voltage of each single cell is a good value and it is estimated that the amount of moisture in the anode off gas is low (at the time of hydrogen circulation), the control unit 60 closes the hydrogen purge valve 24 and does not react. The anode off-gas containing this hydrogen is returned to the ejector 23 so that the hydrogen is circulated and used efficiently.
However, the hydrogen purge method is not limited to the method based on the cell voltage as described above, and may be a method of opening the hydrogen purge valve 24 intermittently for a predetermined time.

<Cathode system-Pipe connection on the air supply side>
The air supply side of the cathode system 30 mainly includes a compressor 31 (pump, supercharger), a humidifier 32, and an on-off valve 33. The compressor 31 is a device that takes in outside air, compresses it, and sends it to the cathode 13 as an oxidant gas, and is connected to a humidifier 32 via a pipe 31a. The compressor 31 is electrically connected to a control unit 60 described later. Further, the compressor 31 is electrically connected to the fuel cell 10 and a storage device (capacitor, secondary battery, etc.) mounted separately from the fuel cell 10, and when the fuel cell 10 is not generating power, When the amount of power generated by the fuel cell 10 is small, electric power is supplied from the battery to operate.
The humidifier 32 includes, for example, a hollow fiber membrane 32a. The hollow fiber membrane 32a exchanges moisture between the air from the compressor 31 and the cathode off gas having a high water content discharged from the cathode 13. The device uses humidified air as the air from the compressor 31. The humidifier 32 is connected to the cathode 13 via a pipe 32b, and humidified air is sent to the cathode 13.

Further, a pipe 31b is branched and provided at a midway position of the pipe 31a, and is connected to the diluter 41 from the pipe 31b via the on-off valve 33 and the pipe 33a. The on-off valve 33 is electrically connected to the control unit 60, and the control unit 60 opens / closes the on-off valve 33 in conjunction with, for example, opening / closing of the hydrogen purge valve 24. Yes. That is, when the control unit 60 opens the on-off valve 33 during the operation of the compressor 31, it is a part of the oxidant gas supplied to the cathode 13 and is dried air before being humidified by the humidifier 32 (hereinafter referred to as “humidifier 32”). , Dry air) is supplied to the diluter 41. More specifically, the on-off valve 33 is opened during the hydrogen circulation in which the hydrogen purge valve 24 of the anode system 20 is closed. On the other hand, the open / close valve 33 is closed during the hydrogen purge when the hydrogen purge valve 24 is opened.
However, the configuration may be such that the on-off valve 33 is not provided and dry air is continuously supplied to the diluter 41 while the compressor 31 is operating. In addition, instead of the on-off valve 33, a throttle (orifice) that suppresses the flow rate of dry air and a flow rate adjustment valve that can adjust the flow rate are provided, and the flow rate of the dry air is adjusted and continuously supplied to the diluter 41. Also good.

<Cathode system-Air connection side piping connection>
The cathode 13 of the fuel cell 10 is connected to the humidifier 32 via a pipe 32 c, and the cathode off gas having a high water content discharged from the cathode 13 is sent to the humidifier 32. The humidifier 32 is connected to the diluter 41 via a pipe 32d. As a result, the cathode off-gas whose water content is slightly reduced by the water exchange in the humidifier 32 is supplied to the diluter 41 via the pipe 32d.
Further, the pipe 32c is provided with a back pressure valve (not shown). By adjusting the back pressure, the pressure of hydrogen on the anode 12 side and the pressure of air on the cathode 13 side in the fuel cell 10 are adjusted. It comes to balance.

<Configuration of fuel cell exhaust gas treatment device>
As shown in FIG. 1, the exhaust gas processing device 40 includes a hydrogen discharge passage P through which hydrogen discharged from the anode of the fuel cell 10 flows, and one of the hydrogen discharged from the fuel cell 10 provided in a branch line. At least a hydrogen reservoir 43 that stores a part and a diluter 41 that is connected to the hydrogen discharge flow path P and dilutes hydrogen by mixing the discharged hydrogen and a diluent gas. In addition, the exhaust gas processing device 40 includes a hydrogen purge valve 24, a second reed valve 42 and a first reed valve 44 provided at the inlet and outlet of the hydrogen reservoir 43, respectively, and a pipe 24a for connecting them. 24c, 24d, 24e, 42a, 43a, 44a, 41a.

<Configuration of hydrogen discharge flow path>
The hydrogen discharge flow path P forms a flow path for discharging the hydrogen discharged from the fuel cell 10 to the outside of the fuel cell vehicle, and a hydrogen dilution line and a branch line at a branch point c on the way. After being divided into two, they are connected so as to join at a connection point d and to be discharged to the outside. The hydrogen discharge flow path P includes the pipes 24a, 24c, 24d, 24e, 41a, 42a, 43a, 44a, a diluter 41, a second reed valve 42, a hydrogen reservoir 43, and a first reed valve 44. It is composed of The pipes 24a, 24c, 24d, 24e, 41a, 42a, 43a, and 44a are not particularly limited in shape such as a cylindrical shape or a rectangular tube shape, but will be described below by taking a cylindrical shape as an example.

  FIG. 2 is a schematic view showing an installation state of a hydrogen reservoir in an exhaust gas processing apparatus for a fuel cell according to an embodiment of the present invention.

  As shown in FIG. 2, a hydrogen reservoir 43 is connected to a branch point c between the hydrogen dilution line and the branch line in the hydrogen discharge passage P, and a pipe (hydrogen reservoir inlet) for leading a part of the hydrogen to the hydrogen reservoir 43 is connected. Channels) 24e and 42a are connected. At the branch point c of the hydrogen discharge flow path P, the pipes 24e and 42a constituting the hydrogen reservoir inlet flow path of the hydrogen reservoir 43 are along the flow path direction of the hydrogen discharge flow path P (flow direction of the main flow of the anode off gas). Is provided. The pipes 24c, 24e, and 42a at the branch point c are arranged in a substantially straight line so that the anode off gas flows smoothly in the main flow path direction by reducing the flow resistance. The pipe 24d communicating with the diluter 41 is provided so as to be orthogonal to the flow path direction, for example. The pipes 24e and 42a correspond to the “hydrogen reservoir inlet channel” described in the claims.

At the branch point c branched from the pipes 24 c and 24 e, the minimum cross-sectional area s 1 of the hydrogen discharge flow path P (pipe 24 d) between the branch point c and the diluter 41 is between the branch point c and the hydrogen reservoir 43. Are formed smaller than the minimum cross-sectional area s2 of the hydrogen reservoir inlet channel (pipes 24e, 42a). That is, the branch line pipes 24e and 42a are formed such that the inner diameter b of the minimum inner diameter part is larger than the inner diameter a of the minimum inner diameter part of the dilution line pipe 24d, and the anode off-gas flowing from the hydrogen purge valve 24 is It is formed so as to easily flow to the second reed valve 42 side by dynamic pressure.
The minimum cross-sectional area s1 of the pipe 24d corresponds to the “minimum cross-sectional area of the hydrogen drainage channel” described in the claims, and the minimum cross-sectional area s2 of the pipes 24e and 42a is described in the claims. This corresponds to “the minimum cross-sectional area of the hydrogen reservoir inlet channel”.

<Configuration of first reed valve (first one-way valve) and second reed valve (second one-way valve)>
As shown in FIG. 2, the first and second reed valves 44, 42 are arranged in a direction in the direction (hydrogen reservoir side) in which anode off-gas is discharged from the fuel cell 10 side (system side) to the outside of the fuel cell vehicle. It is installed on a hydrogen discharge passage P that leads to the fuel cell 10 so as to flow in the direction. The first and second reed valves 44 and 42 are backflow prevention valves that allow the flow in only one direction downstream with respect to the flow of the anode off gas.
The second reed valve 42 is a valve that is disposed in the hydrogen reservoir inlet channel (pipes 24 e and 42 a) at the inlet of the hydrogen reservoir 43 and regulates the flow of hydrogen into the hydrogen reservoir 43. As will be described later, the second reed valve 42 is configured to open when the upstream pressure is equal to or higher than a second predetermined pressure.
The first reed valve 44 is disposed in the hydrogen reservoir outlet flow path (pipe 43a, 44a) at the outlet of the hydrogen reservoir 43 and opens when the upstream pressure is equal to or higher than the first predetermined pressure, as will be described later. It is configured as follows.
The first reed valve 44 corresponds to a “first one-way valve” recited in the claims, and the second reed valve 42 corresponds to a “second one-way valve”.

FIG. 3 is a schematic view showing an example of a second reed valve in the exhaust gas treatment device for a fuel cell according to the embodiment of the present invention.
For example, as shown in FIG. 3, the second reed valve 42 includes a first communication hole 42 d communicating with a pipe 24 e on the fuel cell 10 side (system side) with a partition wall 42 c inside a housing 42 b, a hydrogen A second communication hole 42e that communicates with the pipe 42a on the reservoir 43 side is formed, and a second valve body 42f that opens and closes the first communication hole 42d is installed in the partition wall 42c.
For example, the second reed valve 42 has a pressure difference ΔP (differential pressure ΔP = P1−P2) between the pressure P1 in the first communication hole 42d and the pressure P2 in the second communication hole 42e of the second valve body 42f. When the spring force (second predetermined pressure) is increased, the second valve body 42f that has closed the first communication hole 42d is elastically deformed to open. When the differential pressure ΔP becomes lower than the spring force, the second reed valve 42 causes the second valve body 42f to close the first communication hole 42d by the spring force, and the anode off gas is diluted from the hydrogen reservoir 43 side. In addition to preventing the gas from flowing back to the side 41, the anode off-gas that has entered the hydrogen reservoir 43 is closed so that the hydrogen reservoir 43 stores the anode off-gas.

  As shown in FIG. 1, the first reed valve 44 has an upstream end connected to a pipe 43 a provided at the outlet of the hydrogen reservoir 43 and a downstream end provided on the downstream side of the diluter 41. It consists of the backflow prevention valve connected to the piping 44a connected to the piping 41a for use. The first valve body (not shown) of the first reed valve 44 has a spring force larger than the spring force of the second valve body 42f (see FIG. 3) of the second reed valve 42. What is the second valve body 42f? It consists of valve bodies with different spring constants. The first reed valve 44 stores the anode off gas in the hydrogen reservoir 43 at a pressure within the first predetermined pressure, and does not discharge the anode off gas stored in the hydrogen reservoir 43 at a stretch. When the upstream pressure becomes equal to or higher than the first predetermined pressure, the anode valve opens from the first reed valve 44 so that the first valve body opens and gradually flows, and the anode off-gas flows back to the hydrogen reservoir 43 side. This is installed to prevent the cathode off gas from flowing into the hydrogen reservoir 43 from the pipe 41 a downstream of the diluter 41.

<Configuration of hydrogen reservoir>
The hydrogen reservoir 43 is a tank for temporarily storing the anode off gas and discharging it little by little so that a large amount of the anode off gas containing hydrogen does not flow from the exhaust pipe 41a to the outside at once. The hydrogen reservoir 43 is provided in the branch line, and has an inlet connected to the second reed valve 42 and an outlet connected to a pipe 41 a downstream of the diluter 41 via the first reed valve 44. The hydrogen reservoir 43 is configured such that the first predetermined pressure at which the first reed valve 44 on the outlet side opens and closes is set higher than the second predetermined pressure at which the second reed valve 42 on the inlet side opens and closes. Off gas can be stored at high pressure. That is, the anode off gas blown into the hydrogen reservoir 43 is stored in the hydrogen reservoir 43 until the back flow is prevented by the second reed valve 42 and the opening pressure of the first reed valve 44 on the outlet side is reached. When the pressure is high and the spring force of the first valve body (not shown) is exceeded, it flows to the pipe 44a side.

<Configuration of the diluter>
FIG. 4 is a perspective view having a partial cross section showing an example of a diluter.
As shown in FIG. 4, the diluter 41 includes a stagnation unit 41b, a partition plate 41c that partitions the stagnation unit 41b in a predetermined manner, a purge hydrogen introduction part of the pipe 24d, a dry air introduction part of the pipe 33a, and a pipe 32d. A cathode offgas inlet portion is mainly provided.

  The staying device 41b is a columnar casing whose outer shape is horizontal and has an internal space. The partition plate 41c is provided in the staying device 41b, and the internal space is incompletely partitioned in the axial direction of the staying device 41b. More specifically, the internal space of the staying device 41b is partitioned by the partition plate 41c into an upstream staying chamber 41e and a downstream staying chamber 41f. It communicates with the upper part.

  The downstream end portion of the pipe 24d through which the anode off gas containing unreacted hydrogen flows during the hydrogen purge passes through the end plate on the upstream side of the retainer 41b, and the tip extends into the stay chamber 41e. And it is comprised so that the anode off gas which blows off from the front-end | tip of the piping 24d may be sprayed on the partition plate 41c.

  The downstream end portion (dry air introduction portion) of the pipe 33a through which the dry air (oxidant gas) flows is a portion that guides the dry air into the staying device 41b, and penetrates the end plate on the upstream side of the staying device 41b, and its tip Extends into the retention chamber 41e. And it is comprised so that the dry air which blows off from the front-end | tip of the piping 33a is sprayed on the partition plate 41c.

A pipe (dilution gas flow part) 32d through which the cathode off-gas for dilution (dilution gas) flows passes through the lower part of the staying device 41b in the axial direction. The piping 32d in the staying device 41b includes a hydrogen discharge port 32d1 for discharging the mixed gas of the anode offgas and the dry air staying in the staying device 41b to the cathode offgas passage (pipe 32d), and the inside of the staying device 41b. A plurality of drain holes 32d2 and 32d2 for discharging the water to the outside are formed at appropriate positions.
Then, the anode off-gas that has been retained in the stagnation vessel 41b and diluted with dry air is pushed out to the pipe 32d through the hydrogen discharge port 32d1 by the dry air introduced thereafter, and the anode off-gas is supplied to the hydrogen discharge port 32d1. In the downstream side pipe 32d, it is further diluted with the cathode off gas and then exhausted to the outside.
The cathode off gas flowing through the pipe 32d corresponds to “dilution gas” described in the claims.

<Configuration of other equipment>
The IG 52 is a start switch for the fuel cell vehicle and a start switch for the fuel cell system S. And IG52 is electrically connected with control part 60, and control part 60 is interlocked with ON / OFF of IG52. When the IG 52 is turned off, the fuel cell 10 stops power generation.
The control unit 60 includes, for example, a CPU, ROM, RAM, various interfaces, electronic circuits, and the like. The control unit 60 is electrically connected to the shutoff valve 22, the hydrogen purge valve 24, the compressor 31, and the on-off valve 33, and appropriately controls them.

≪Operation of exhaust gas treatment device≫
Next, the operation of the exhaust gas treatment device 40 of the fuel cell 10 will be described with reference mainly to FIG.
When the hydrogen purge valve 24 shown in FIG. 1 is opened and hydrogen purge is performed, the high-pressure anode off gas is supplied from the fuel cell 10 to the pipe 24a, the hydrogen purge valve 24, the pipe 24c, the pipe 24e, and the second reed valve. It flows to the hydrogen reservoir 43 via 42 and flows to the diluter 41 via the pipe 24d branched from the pipe 24c.

  At this time, as shown in FIG. 2, the anode off-gas has a minimum cross-sectional area s 1 of the hydrogen discharge flow path P (pipe 24 d) between the branch point c and the diluter 41 between the branch point c and the hydrogen reservoir 43. Since the hydrogen reservoir inlet channel (pipe 24e) is formed to be smaller than the minimum cross-sectional area s2, the second reed valve 42 flows in a large amount toward the hydrogen reservoir 43 side. Further, the anode off gas is provided in such a manner that the direction at the branch point c of the hydrogen reservoir inlet channel is along the direction of the channel direction of the hydrogen discharge channel P (pipe 24e) at the branch point c. Since it flows in the same direction, the flow resistance is small and it flows smoothly to the second reed valve 42 side.

As shown in FIG. 3, the anode off gas has a pressure difference ΔP between the pressure P1 in the first communication hole 42d of the second reed valve 42 and the pressure P2 in the second communication hole 42e, and the spring of the second valve body 42f. When the force increases due to the force, the second valve body 42 f that has closed the first communication hole 42 d opens and flows into the hydrogen reservoir 43.
The anode off-gas that has flowed into the hydrogen reservoir 43 causes the spring force of the first valve body (not shown) of the first reed valve 44 on the outlet side to be applied to the second valve body 42f of the second reed valve 42 on the inlet side. Since the opening / closing pressure of the first reed valve 44 is higher than the opening / closing pressure of the second reed valve 42 due to being set larger than the spring force, the first reed valve 44 is stored in a high pressure state by the first predetermined pressure. Is done.

Then, the anode off gas stored in the hydrogen reservoir 43 continues to be stored until the opening pressure of the first reed valve 44 becomes high, and the internal pressure of the hydrogen reservoir 43 becomes the spring force of the first valve body (not shown). When the pressure exceeds the value, the pipe 44a is slowly discharged into the cathode off gas in the pipe 41a little by little and then discharged to the outside of the fuel cell vehicle.
As described above, the anode off-gas in the hydrogen reservoir 43 is set to a first value little by little at the time of hydrogen purge because the valve pressure at which the first reed valve 44 on the outlet side (downstream side) of the hydrogen reservoir 43 is opened and closed is set high. The reed valve 44 flows out. For this reason, the anode off gas containing a high concentration of hydrogen in the branch line is directly discharged into the cathode off gas in the pipe 41a, and then discharged into the atmosphere after the hydrogen concentration is lowered.

On the other hand, the anode off-gas flowing from the pipe 24d into the diluter 41 has the minimum cross-sectional area s1 of the pipe 24d between the branch point c and the diluter 41, and the minimum disconnection of the pipe 24e between the branch point c and the hydrogen reservoir 43. By being stored in the hydrogen reservoir 43 which is smaller than the area b, a large amount of anode off gas is suppressed from flowing to the branch line side. For this reason, the flow rate flowing into the diluter 41 is reduced. During the hydrogen purge, the anode off-gas that has entered the diluter 41 temporarily has a high hydrogen concentration in the staying device 41b. However, since the hydrogen is then diluted, the hydrogen concentration in the staying device 41b is low. (See FIG. 5).
Further, dry air is sent from the pipe 33a into the staying device 41b, and further, a cathode off gas flows through the pipe 32d. For this reason, the hydrogen fed into the staying device 41b stays in the staying chambers 41e and 41f, is mixed and diluted with dry air, then flows into the pipe 32d through the hydrogen discharge port 32d1, and the cathode in the pipe 32d. It is diluted with off-gas and exhausted outside the fuel cell vehicle.

  FIG. 5 is a graph showing changes in the hydrogen concentration in the diluter and at the downstream of the diluter at the time of purging, and comparing the change in hydrogen concentration with and without the hydrogen reservoir. is there. The hydrogen concentration B downstream of the diluter 41 shown in FIG. 5 is data measured at a measurement point downstream of the connection point d where the pipe 41a and the pipe 44a shown in FIG.

When the hydrogen purge valve 24 is opened as described above, the anode off gas flows into the diluter 41 to dilute the hydrogen (see FIG. 1). Since the anode off gas flows into the diluter 41 so as to follow the purge flag in which the hydrogen purge valve 24 is operated, the hydrogen concentration A in the diluter 41 temporarily increases as shown in FIG.
The hydrogen concentration A in the diluter 41 flows to the diluter 41 by providing the hydrogen reservoir 43 in the branch line as compared with the hydrogen concentration C in the diluter 41 of the comparative example that does not include the branch line. Since the flow rate is suppressed and reduced, it is diluted efficiently. As a result, the time for dilution by the diluter 41 is reduced to a short time.

  Further, as shown in FIG. 5, the hydrogen concentration B discharged from the pipe 41a downstream of the diluter 41 to the outside of the fuel cell vehicle is downstream of the diluter of the comparative example that does not include the hydrogen reservoir 43 and the branch line. Compared with the exhaust hydrogen concentration D, it is decreased by improving the dilution processing efficiency, and after being diluted with the cathode off gas, the time for exhausting is also shortened. This prevents high-concentration hydrogen from being discharged outside the fuel cell vehicle.

  The present invention is not limited to the above-described embodiment, and various modifications and changes can be made within the scope of the technical idea. The present invention extends to these modifications and changes. Of course.

  In the above-described embodiment, the fuel cell system S in which the exhaust gas treatment device 40 of the fuel cell 10 including the diluter 41, the second reed valve 42, the hydrogen reservoir 43, and the first reed valve 44 is assembled. Although illustrated about the case where it mounts in a fuel cell vehicle, the usage mode of fuel cell system S is not limited to this, For example, it may be a stationary fuel cell system for home use.

  Further, the pipe 44a installed on the downstream side of the first reed valve 44 shown in FIG. 1 is not limited to being connected to the pipe 41a at the connection point d. For example, the upstream end is connected to the first lead. The downstream end may be connected to the diluter 41 by connecting to the valve 44. By doing so, the anode off-gas stored in the hydrogen reservoir 43 through the branch line is purged and the diluter 41 is little by little at the timing when the anode off-gas flows from the pipe 24d to the diluter 41 after the purge. Therefore, the hydrogen is prevented from being discharged to the outside at once, and the hydrogen is efficiently diluted before being discharged to the outside through the pipe 41a.

  In the above-described embodiment, the case where the second reed valve 42 is provided on the inlet side of the hydrogen reservoir 43 and the first reed valve 44 is provided on the outlet side of the hydrogen reservoir 43 has been described. It is not limited and only the 1st reed valve 44 may be sufficient. Even in this case, the anode gas can be stored in the hydrogen river bar 43, and when the pressure in the hydrogen reservoir 43 becomes equal to or higher than the first predetermined atmospheric pressure, the hydrogen can be discharged downstream.

  Further, in the above-described embodiment, one branch line (pipe 24e, 42a, 43a, 44a) provided with the first reed valve 44, the second reed valve 42, and the hydrogen reservoir 44 is provided in the hydrogen discharge passage P. However, there may be a plurality of branch lines. By doing in this way, the flow volume which flows into the diluter 41 can be adjusted suitably.

  As shown in FIG. 2, a branch point c where the hydrogen discharge flow path P is divided into a hydrogen dilution line pipe 24d and a branch line pipe 24e is provided with a pipe 24e in a straight line with respect to the pipe 24c. , 24e is described with reference to an example in which the pipe 24e is connected by a T-shaped joint so as to be orthogonal to the pipe 24e, but is not limited thereto. For example, the pipe 24e may be provided in a state of being bent in an arc shape with respect to the pipe 24c, and the pipe 24d may be disposed obliquely with respect to the pipes 24c and 24e by a Y-shaped joint or the like.

It is a block diagram which shows the structure of the exhaust gas processing apparatus of the fuel cell which concerns on this embodiment. It is the schematic which shows the installation state of the hydrogen reservoir in the exhaust gas processing apparatus of the fuel cell which concerns on embodiment of this invention. It is the schematic which shows an example of the 2nd reed valve in the exhaust gas processing apparatus of the fuel cell which concerns on embodiment of this invention. It is a perspective view which has a partial cross section which shows an example of the diluter in the exhaust gas processing apparatus of the fuel cell which concerns on embodiment of this invention. It is a graph which shows the change of the hydrogen concentration in the diluter at the time of a purge, and the downstream of a diluter, Comprising: It is the graph which compared the change of the hydrogen concentration in the case where there is no hydrogen reservoir and the case where there is no hydrogen reservoir.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Fuel cell 12 Anode 24 Hydrogen purge valve 24a, 24c Piping 24d Piping (diluent inflow channel) (hydrogen diluting line)
24e, 42a Piping (hydrogen reservoir inlet channel) (branch line)
40 Exhaust gas treatment equipment 41 Diluter 41a Piping (downstream piping of the diluter)
42 Second reed valve (second one-way valve)
43 Hydrogen reservoir 43a, 44a Piping (hydrogen reservoir outlet flow path) (branch line)
44 First reed valve (first one-way valve)
c Branch point P Hydrogen discharge flow path S Fuel cell system s1 Minimum cross-sectional area (minimum cross-sectional area of the hydrogen discharge flow path between the branch point and the diluter)
s2 Minimum cross-sectional area (minimum cross-sectional area of the hydrogen reservoir inlet channel between the branch point and the hydrogen reservoir)

Claims (5)

A hydrogen discharge passage through which hydrogen discharged from the anode of the fuel cell flows;
A diluter for diluting the hydrogen by mixing the discharged hydrogen and a dilution gas, and connected to the hydrogen discharge flow path;
The hydrogen discharge flow path upstream of the diluter is provided with a branch line, and a hydrogen reservoir for storing a part of the discharged hydrogen is provided in the branch line. Gas processing device. A hydrogen reservoir outlet channel connecting the outlet of the hydrogen reservoir and the diluter or a downstream pipe of the diluter;
2. A fuel cell discharge according to claim 1, further comprising: a first one-way valve provided in the hydrogen reservoir outlet channel and opened when the pressure on the upstream side is equal to or higher than a first predetermined pressure. Gas processing device. A second one-way valve for restricting the flow of hydrogen into the hydrogen reservoir on the inlet side of the hydrogen reservoir;
3. The fuel cell exhaust gas processing device according to claim 1, wherein the second one-way valve opens when a pressure on an upstream side thereof is equal to or higher than a second predetermined pressure. 4. A hydrogen reservoir inlet flow for connecting the hydrogen reservoir to a branch point where the hydrogen discharge flow path branches into the branch line and a hydrogen dilution line communicating with the diluter, and leading a part of the hydrogen to the hydrogen reservoir. With a road,
4. The fuel according to claim 1, wherein an orientation of the hydrogen reservoir inlet channel at the branch point is along a direction of the hydrogen discharge channel at the branch point. 5. Battery exhaust gas treatment device. The minimum cross-sectional area of the hydrogen discharge flow path between the branch point and the diluter is smaller than the minimum cross-sectional area of the hydrogen reservoir inlet flow path between the branch point and the hydrogen reservoir. Item 5. An exhaust gas treatment device for a fuel cell according to Item 4.

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