JP4914036B2 - Fuel cell exhaust gas treatment device - Google Patents

Description

  The present invention relates to an exhaust gas treatment device for a fuel cell that dilutes hydrogen discharged from an anode of the fuel cell.

  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. This fuel cell is being applied in a wide range such as a fuel cell vehicle driven by the generated power and a household power source, and its application range is expected to be expanded in the future. 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 technology that employs a hydrogen circulation system that returns the discharged unreacted hydrogen to the hydrogen supply side and circulates hydrogen has been proposed.

  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 (conductivity) of protons (hydrogen ions) in the electrolyte membrane, for example, gas (hydrogen, oxygen) supplied to the cathode side or anode side of the fuel cell A method of humidifying air containing air).

  Therefore, in the case of a fuel cell system that employs a hydrogen circulation system, the amount of water 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. Therefore, 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, and externally ( A technique for discharging to the outside air) has been proposed (see Patent Document 1).

This technique will be further described. In order to dilute the hydrogen discharged by the hydrogen purge, (1) one of the cathode offgas from the cathode offgas flow path through which the cathode offgas (dilution gas) discharged from the cathode of the fuel cell flows. (2) The cathode offgas thus taken out and the anode offgas containing hydrogen are mixed in a mixing chamber (dilution chamber). (3) After diluting the hydrogen, it is returned to the cathode offgas flow path for further dilution. To the outside.
JP 2002-289237 A (paragraph number 0068, FIG. 1)

Thus, further improvement of the technology is desired for discharging the fuel cell at a reduced hydrogen concentration.
Therefore, an object of the present invention is to provide a fuel cell exhaust gas treatment device that lowers the concentration of hydrogen discharged from a fuel cell and discharges it to the outside.

As a means for solving the above-mentioned problems, the present invention provides a fuel cell exhaust gas treatment apparatus for diluting hydrogen discharged from the anode of the fuel cell with a diluent gas and discharging the hydrogen to the outside. A hydrogen introduction means for dividing the hydrogen into a plurality of dilution gas flow paths through which the dilution gas flows, the hydrogen introduction means downstream of the discharge hydrogen flow path through which the hydrogen discharged from the anode flows A first dilution flow path and a second dilution flow path connected to the end, branched at a branching point and then merged at a merged point, and connected to the dilution gas flow channel downstream of the merged point; Provided in the first dilution flow path between the junction and the first check valve for preventing hydrogen backflow, and provided in the second dilution flow path between the branch point and the junction. Preventing the back flow of hydrogen, the first check valve A second check valve having the same specification, a first pressure loss body that is provided in the first dilution flow path between the first check valve and the junction, and applies pressure loss; and the second A second pressure loss body that is provided in the second dilution flow path between the check valve and the junction point and that imparts the same pressure loss as the first pressure loss body, the branch point and the junction point The first dilution flow path and the second dilution flow path are equal in length, and the downstream flow rates of the first pressure loss body and the second pressure loss body are set to be equal, The first A flow path volume of the first dilution flow path between the branch point and the first pressure loss body, and the second A flow of the second dilution flow path between the branch point and the second pressure loss body The second volume channel volume of the second dilution channel between the second pressure loss body and the confluence is equal to the channel volume. A exhaust gas processing device for a fuel cell, wherein the Okiiko than the 1B passage volume of said first diluent flow path between the said joining point and the first pressure loss thereof.

According to such an exhaust gas processing apparatus for a fuel cell, the hydrogen discharged from the anode of the fuel cell is divided into a plurality (two in the first embodiment) by the hydrogen introduction means, and is supplied to the dilution gas flow path. be introduced. That is, hydrogen discharged from the anode is divided and introduced into the diluting gas (cathode off-gas in the embodiment described later) flowing through the diluting gas flow path by the hydrogen introducing means. Then, the separately introduced hydrogen is diluted by the diluting gas according to the introduction timing, the hydrogen concentration is lowered, and after the hydrogen concentration is reliably reduced in this way, the hydrogen is discharged to the outside. be able to.
In this way, hydrogen discharged from the anode is divided into a plurality of parts by the hydrogen introduction means and introduced into the dilution gas through which the dilution gas flows, so that the hydrogen discharged from the anode is directly used as the dilution gas without being divided. Compared with the case where it introduce | transduces, hydrogen can be diluted efficiently and hydrogen concentration can be reduced.
Moreover, it is preferable to set a time difference as much as possible for the timing of introducing the divided hydrogen into the gas flow path for dilution in order to dilute the hydrogen well.

According to such an exhaust gas treatment device for a fuel cell, by providing a plurality of dilution passages branched from the discharge hydrogen passage, hydrogen discharged from the anode of the fuel cell is supplied from the discharge hydrogen passage. It flows into the dilution flow path and is divided into a plurality. Then, the flow rate setting means provided in each dilution channel is set so that the downstream flow rate becomes equal.
(1) The flow rate downstream of each flow rate setting means is equal, and (2) the flow volume of each dilution flow path between each flow rate setting means and the dilution gas flow path is different. As a result, a difference occurs in the time required for the divided hydrogen to reach the dilution gas flow path. Therefore, the divided hydrogen is sequentially introduced into the dilution gas flow path, diluted with the dilution gas, and the hydrogen concentration is lowered.

  As a means for solving the above-mentioned problems, the present invention provides a fuel cell exhaust gas treatment apparatus for diluting hydrogen discharged from the anode of the fuel cell with a diluent gas and discharging the hydrogen to the outside. A hydrogen introduction means for dividing the hydrogen into a plurality of dilution gas flow paths through which the dilution gas flows, the hydrogen introduction means downstream of the discharge hydrogen flow path through which the hydrogen discharged from the anode flows A first dilution flow path and a second dilution flow path connected to the end, branched at a branching point and then merged at a merged point, and connected to the dilution gas flow channel downstream of the merged point; Provided in the first dilution flow path between the junction and the first check valve for preventing hydrogen backflow, and provided in the second dilution flow path between the branch point and the junction. Preventing the back flow of hydrogen, the first check valve A second check valve having the same specification, a first pressure loss body that is provided in the first dilution flow path between the first check valve and the junction, and applies pressure loss; and the second A second pressure loss body that is provided in the second dilution flow path between the check valve and the junction point and that imparts a pressure loss greater than that of the first pressure loss body, the branch point and the junction point The first diluting flow path and the second diluting flow path are equal in length to each other, and the downstream flow rate of the second pressure loss body is smaller than the downstream flow rate of the first pressure loss body. The first A channel volume of the first dilution channel between the branch point and the first pressure loss body, and the second between the branch point and the second pressure loss body. The first dilution between the first pressure loss body and the confluence is equal to the second A channel volume of the dilution channel. An exhaust gas processing apparatus for a fuel cell, wherein a first B flow path volume of a passage is equal to a second B flow path volume of the second dilution flow path between the second pressure loss body and the junction. is there.

According to such an exhaust gas treatment device for a fuel cell, by providing a plurality of dilution passages branched from the discharge hydrogen passage, hydrogen discharged from the anode of the fuel cell is supplied from the discharge hydrogen passage. It flows into the dilution flow path and is divided into a plurality. And the flow volume of the downstream side is set so that it may differ by the flow volume setting means provided in each dilution flow path.
(1) The flow rate downstream of each flow rate setting means is different, and (2) the flow volume of each dilution flow path between each flow rate setting means and the dilution gas flow path is equal. As a result, a difference occurs in the time required for the divided hydrogen to reach the connection point with the dilution gas flow path. Therefore, the divided hydrogen is sequentially introduced into the dilution gas flow path, and diluted with the dilution gas, so that the hydrogen concentration is lowered.

  ADVANTAGE OF THE INVENTION According to this invention, the density | concentration of the hydrogen discharged | emitted from the fuel cell can be made low, and the exhaust gas processing apparatus of the fuel cell discharged | emitted outside can be provided.

  Embodiments of the present invention will be described below with reference to the drawings as appropriate. In the description of each embodiment, the same constituent elements are denoted by the same reference numerals, and redundant descriptions are omitted.

<< First Embodiment >>
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 to 3. In the drawings to be referred to, FIG. 1 is a diagram showing a configuration of a fuel cell system according to a first embodiment. FIG. 2 is a configuration diagram of the diluter according to the first embodiment. FIG. 3 is a graph showing actions and effects of the diluter according to the first embodiment.

≪Configuration of fuel cell system≫
As shown in FIG. 1, the fuel cell system S according to the present embodiment is a system mounted on a fuel cell vehicle, and the fuel cell vehicle uses an electric motor (travel motor) for traveling by the generated power of the fuel cell 10. It is designed to run with rotation.
The fuel cell system S includes a fuel cell 10, an anode system 20 that supplies and discharges hydrogen (fuel gas, reaction gas) to the anode 12 of the fuel cell 10, and air (oxidant gas, reaction) to the cathode 13 of the fuel cell 10. Gas)), a diluter 40A (fuel cell exhaust gas treatment device) for diluting hydrogen discharged from the anode system 20 at a position downstream of the anode system 20 and the cathode system 30, and ECU 50 (Electronic Control Unit, control device) to be controlled is mainly provided.

<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. Each single cell is connected to a cell voltage detection monitor (not shown) for detecting the output voltage (hereinafter, cell voltage). The cell voltage detection monitor is electrically connected to the ECU 50, and the ECU 50 detects the cell voltage of each single cell.

<Anode system-hydrogen supply side>
The hydrogen supply side of the anode system 20 mainly includes a hydrogen tank 21 in which hydrogen is stored, a shut-off valve 22, and an ejector 23 toward the downstream side (fuel cell 10 side). The hydrogen tank 21 is connected to the shutoff valve 22 via a pipe 21a. The shut-off valve 22 is electrically connected to an ECU 50 described later, and the ECU 50 opens / closes the shut-off valve 22 as appropriate. The shutoff valve 22 is connected to the ejector 23 via a pipe 22a, and the ejector 23 is connected to the anode 12 of the fuel cell 10 via the pipe 23a. Furthermore, a pressure reducing valve (not shown) is provided in the pipe 22a. Therefore, when the ECU 50 opens the shut-off valve 22, hydrogen is reduced from the hydrogen tank 21 to a predetermined pressure by the pressure reducing valve and then supplied to the anode 12 of the fuel cell 10.

<Anode system-Hydrogen discharge side>
The hydrogen discharge side of the anode system 20 is mainly provided with a hydrogen purge valve 24. The hydrogen purge valve 24 is connected to the downstream side of the anode 12 of the fuel cell 10 via a pipe 24a, and an anode off gas containing unreacted hydrogen discharged from the anode 12 of the fuel cell 10 passes through the pipe 24a. It flows toward the hydrogen purge valve 24. A midway position of the pipe 24a is connected to the ejector 23 through the pipe 24b. The hydrogen purge valve 24 is connected to the diluter 40A via the pipe 24c.
In the first embodiment, the insides of the pipes 24a and 24c are “exhaust hydrogen passages through which hydrogen discharged from the anode flows” in the claims.

The hydrogen purge valve 24 is electrically connected to the ECU 50, and the ECU 50 appropriately opens / closes the hydrogen purge valve 24.
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 ECU 50 opens the hydrogen purge valve 24, and the anode off gas having a high water content is sent to the diluter 40A via the pipe 24c. Note that the anode off-gas sent to the diluter 40A at the time of hydrogen purge includes nitrogen, etc. in addition to hydrogen and moisture.
On the other hand, if the cell voltage of each single cell is a good value and the water content in the anode off-gas is estimated to be low (hydrogen circulation), the ECU 50 closes the hydrogen purge valve 24 and removes unreacted hydrogen. The contained anode off-gas is returned to the ejector 23 so that hydrogen circulates and hydrogen is 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-Air supply side>
The air supply side of the cathode system 30 mainly includes a compressor 31 (pump, supercharger) and a humidifier 32.
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 the ECU 50. Further, the compressor 31 is connected to the fuel cell 10 and a battery (a capacitor, a 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 generation is small, electric power is supplied from the battery to operate.

  The humidifier 32 incorporates, for example, a hollow fiber membrane 32a. The hollow fiber membrane 32a exchanges moisture between the air from the compressor 31 and the cathode offgas having a high moisture content discharged from the cathode 13, This is equipment that uses air from the compressor 31 as humidified air. The humidifier 32 is connected to the cathode 13 via a pipe 32 b so that humidified air is sent to the cathode 13.

<Cathode system-Air discharge side>
Explaining the air discharge side of the cathode system 30, 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 supplied to the humidifier 32. It is supposed to be sent. The humidifier 32 passes through the diluter 40A via the pipe 32d, and the downstream end of the pipe 32d is open to the outside air. As a result, the cathode off-gas whose water content has been slightly reduced due to the water exchange in the humidifier 32 is discharged into the outside air via the diluter 40A 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.

<Diluter>
The diluter 40A is a device that divides the amount (volume) of the anode off-gas into two and introduces it into the cathode off-gas passage in the pipe 32d through which the cathode off-gas flows with a time difference. As shown in FIG. 2, the diluter 40A includes a dilution pipe 41A (hydrogen introduction means), pressure loss bodies 42A and 42A (flow rate setting means, pressure setting means, hydrogen introduction means), and check valves 43 and 43 (reverse flow). Prevention means) and a part of a pipe 32d (dilution gas flow pipe) having a cathode off gas (dilution gas) flow path through which the cathode off gas (dilution gas) flows.

[Dilution piping]
The dilution pipe 41A connects the downstream end of the pipe 24c through which the anode off gas flows and the connection point J1 in the middle of the pipe 32d through which the cathode off gas flows. More specifically, the dilution pipe 41A is bifurcated at the branch point T1 toward the downstream side, and then merges at the junction point C1 and is connected to the pipe 32d at the connection point J1. The inside of the dilution pipe 41A is the dilution flow paths W1 and W2. That is, since the dilution pipe 41A is bifurcated, the diluter 40A has two dilution flow paths W1 and W2.
And the flow path length of the dilution flow paths W1 and W2 between the branch point T1 and the merge point C1 is set to be equal.
Here, for easy understanding, a route passing through the left dilution flow path W1 shown in FIG. 2 is a left route, and a route passing through the right dilution flow path W2 is a right route.

[Dilution flow path between branch point and each pressure loss body]
The dilution pipe 41A between the branch point T1 and the pressure loss bodies 42A and 42A has the same shape. That is, the dilution flow paths W1, W2 between the branch point T1 and the pressure loss bodies 42A, 42A are the same, and the flow volume of the dilution flow paths W1, W2 between the branch point T1 and the pressure loss bodies 42A, 42A are the same. Is set. The flow volume of the dilution flow paths W1, W2 between the branch point T1 and the pressure loss bodies 42A, 42A is set in accordance with the amount of anode off gas that flows into the hydrogen purge valve 24 when the hydrogen purge valve 24 is opened. Is done.

[Dilution flow path between each pressure loss and confluence]
On the other hand, the shape of the dilution pipe 41A between each pressure loss body 42A and the junction C1 is different, and the dilution pipe 41A of the right route is partially thicker than the dilution pipe 41A of the left route. That is, between the pressure loss bodies 42A, 42A and the confluence C1, the flow volume V2 of the dilution flow path W2 related to the right route is larger than the flow volume V1 of the dilution flow path W1 related to the left route. (V1 <V2). Since the dilution pipe 41A between the junction C1 and the connection point J1 is shared by the left route and the right route, the pressure loss bodies 42A and 42A, that is, between the pressure loss bodies 42A and 42A and the connection point J1. And the cathode off-gas flow channel in the pipe 32d, the flow channel volume related to the right route is larger than the flow channel volume related to the left route. That is, between the pressure loss bodies 42A and 42A and the connection point J1 (cathode off-gas flow channel), the flow channel volume related to the right route and the flow channel volume related to the left route are different.

[Pressure loss body]
The pressure loss bodies 42A and 42A are respectively provided in the dilution flow paths W1 and W2 between the branch point T1 and the merge point C1 so as to protrude from the inner surface of the dilution pipe 41A with the same protrusion amount. By giving the same pressure loss to the anode off-gas flowing through the dilution flow paths W1, W2, the pressure of the anode off-gas downstream of each pressure loss body 42A is set to be the same. The flow rate of the anode off gas flowing through the dilution channels W1 and W2 is set to be equal.

More specifically, for example, at a certain moment after the anode off gas flows into the dilution pipe 41A, the upstream side of each pressure loss body 42A becomes the same pressure P0, and the downstream side of each pressure loss body 42A becomes the same pressure P1. Thereby, at the certain moment, the flow rate Q1 of the cathode off-gas downstream of each pressure loss body 42A is set to be equal.
The size of the pressure loss bodies 42A and 42A is not affected by the flow channel volume V1 and the flow channel volume V2 having different flow rates Q1 and Q1, so that the flow channel cross-sectional areas of the dilution flow channels W1 and W1 are partially limited. Set to be smaller.

[Check valve]
The check valves 43 and 43 provided in the left route and the right route have the same specifications, and the backflow prevention provided in the dilution flow paths W1 and W2 between the branch point T1 and the two pressure loss bodies 42A, respectively. Means. Thereby, the back flow of the anode off gas flowing into the dilution flow paths W1, W2 is prevented. As such a check valve 43, it can select from a well-known thing suitably, and can be used.

  Here, in the first embodiment, “hydrogen discharged from the anode is divided into a plurality of portions and introduced into a cathode offgas passage (dilution gas passage) through which the cathode offgas (dilution gas) flows. The “hydrogen introducing means” includes a dilution pipe 41A and pressure loss bodies 42A and 42A.

<ECU>
The ECU 50 includes a CPU, ROM, RAM, various interfaces, an electronic circuit, and the like. The ECU 50 is electrically connected to the shutoff valve 22, the hydrogen purge valve 24, and the compressor 31, and appropriately controls them. Further, the ECU 50 is electrically connected to an ignition switch (not shown) and is interlocked with this.

≪Operation of fuel cell system≫
Next, the operation of the fuel cell system S will be briefly described with reference to FIG.
When the ignition switch is turned on by the driver of the fuel cell vehicle, the ECU 50 is activated. The activated ECU 50 opens the shut-off valve 22 to send hydrogen to the anode 12, operates the compressor 31 to send humidified air containing oxygen to the cathode 13, closes the hydrogen purge valve 24, and circulates hydrogen to produce fuel. It is assumed that the battery 10 can generate power. In this state, when the fuel cell 10 receives a power request from an external load connected to its output terminal, the fuel cell 10 normally generates power. In addition, while the compressor 31 operates in this way, the cathode off gas flows in order in the piping 32c and the piping 32d.

  In this way, when the ECU 50 detects that the cell voltage has decreased with respect to a predetermined cell voltage via the cell voltage detection monitor while the fuel cell 10 is normally generating power, the ECU 50 is in the anode off-gas state. It is estimated that the amount of impurities such as moisture and nitrogen is high. Next, the ECU 50 temporarily opens the hydrogen purge valve 24, discharges the anode off gas containing impurities, and sends it to the diluter 40A.

<Operation and effect of diluter>
Next, the operation and effect of the diluter 40A into which the anode off gas has been sent in this way will be described with reference to FIGS.
As shown in FIG. 2, the anode off gas containing hydrogen fed into the diluter 40A proceeds from the pipe 24c to the dilution pipe 41A, that is, to the dilution flow paths W1 and W2, and the amount (volume) of the anode off gas at the branch point T1. ) Is divided into two. Then, the anode off gas divided into two passes through the dilution flow paths W1 and W2 related to the left route and the right route, respectively opens the check valve 43, reaches the pressure loss body 42A, and then passes through.

  In both the left route and the right route, at a certain moment after the anode off gas passes through the pressure loss body 42A, the upstream side of each pressure loss body 42A becomes the pressure P0, and the downstream side becomes the pressure P1. The flow rate of the anode off gas flowing through the dilution flow paths W1 and W2 on the downstream side of each pressure loss body 42A is the flow rate Q1.

The anode off-gas having such a flow rate Q1 flows in the dilution flow path W1 portion of the flow path volume V1 between the pressure loss body 42A and the merge point C1 in the left route, and between the pressure loss body 42A and the merge point C1 in the right route. Flows through the dilution flow path W2 of the flow path volume V2.
Here, since the flow volume V2 of the right route is larger than the flow volume V1 of the left route (V2> V1), the flow rate f1 of the anode off gas that follows the left route is higher than the flow rate f2 of the anode off gas that follows the right route. It becomes higher (f1> f2). Therefore, after the anode off gas that follows the left route reaches the junction C1, the anode off gas that follows the right route reaches the junction C1.
That is, at the connection point J1 downstream of the junction C1, (1) the anode off-gas from the left route arrives and is diluted by the cathode off-gas, and (2) the anode off-gas from the right route arrives and reaches the cathode off-gas. Diluted by

  Regarding this, the opening / closing timing of the hydrogen purge valve 24, the peak of the hydrogen concentration at the station X1 upstream of the diluter 40A, and the peak of the hydrogen concentration at the station Y1 downstream of the diluter 40A. Further description will be given with reference to FIG.

  As shown in FIG. 3A, when the hydrogen purge valve 24 is opened once by the ECU 50 within a predetermined time, at the measuring point X1 upstream of the branch point T1, as shown in FIG. 3B. Then, one peak H1 corresponding to hydrogen contained in the anode off-gas discharged by opening the hydrogen purge valve 24 once is detected.

  On the other hand, at the measurement point Y1 downstream of the connection point J1, as described above, the hydrogen in the anode off-gas from the left route and the hydrogen in the anode off-gas from the right route arrive at the connection point J1 sequentially. As shown in FIG. 3C, the peak H2 corresponding to hydrogen in the anode offgas via the left route and the peak H3 corresponding to hydrogen in the anode offgas via the right route are diluted with the cathode offgas. Are detected sequentially.

  As described above, according to the diluter 40A according to the first embodiment, the anode off-gas discharged when the hydrogen purge valve 24 is opened once is divided into two anode off-gases. In order to introduce the anode off gas into the cathode off gas with the timing shifted at the connection point J1, hydrogen contained in the anode off gas can be efficiently diluted, and the hydrogen concentration can be reliably reduced and then discharged to the outside. it can.

<< Second Embodiment >>
Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 4 is a configuration diagram of a diluter according to the second embodiment.

  As shown in FIG. 4, the diluter 40B according to the second embodiment includes a dilution pipe 41B instead of the dilution pipe 41A (see FIG. 2). The dilution pipe 41B is symmetrical as shown in FIG. That is, the flow path volume V1 between the pressure loss body 42A on the left route and the junction C1 is the same as the flow path volume V1 between the pressure loss body 42B and the junction C1 described later on the right route. That is, between the pressure loss bodies 42A and 42B and the connection point J1 (cathode off-gas flow path), the flow path volume related to the right route and the flow path volume related to the left route are equal.

  Further, the diluter 40B includes a pressure loss body 42B in place of the pressure loss body 42A according to the first embodiment in the right route. The amount of protrusion of the pressure loss body 42B from the inner surface of the dilution pipe 41B is larger than the amount of protrusion of the pressure loss body 42A in the left route.

  As a result, the anode off gas flows into the dilution pipe 41B, is divided into a left route and a right route, and at a certain moment after passing through the pressure loss bodies 42A and 42B, the downstream side of the pressure loss body 42B of the right route becomes the pressure loss body of the left route. The pressure P2 is lower than the pressure P1 on the downstream side of 42A (P1> P2). In other words, at a certain moment, the flow rate Q2 of the anode off gas downstream of the pressure loss body 42B on the right route is smaller than the flow rate Q1 of the anode off gas downstream of the pressure loss member 42A on the left route (Q1> Q2). That is, the flow rates of these downstream anode off-gases are set to be different from each other by the different pressure loss bodies 42A and 42B.

  Accordingly, the flow rate f1 of the anode off gas flowing between the pressure loss body 42A on the left route and the junction C1 is higher than the flow rate f3 of the anode off gas flowing between the pressure loss body 42B on the right route and the junction C1 (f1). > F3).

  Therefore, in the diluter 40B according to the second embodiment, as in the diluter 40A according to the first embodiment (see FIG. 2), after the anode off gas from the left route reaches the junction C1, Anode off-gas from the route arrives. That is, (1) the anode off-gas from the left route reaches the connection point J1 downstream of the junction C1, and hydrogen contained therein is diluted by the cathode off-gas, and then (2) the anode from the right route. Off-gas arrives and hydrogen contained therein is diluted.

  In this way, the diluter 40B according to the second embodiment also divides the anode off-gas discharged by the hydrogen purge into two, and the anode off-gas divided into two is shifted in timing at the connection point J1 to the cathode. It can introduce | transduce into off-gas, After having diluted hydrogen contained in anode off-gas efficiently with cathode off-gas and reducing hydrogen concentration, it can exhaust.

≪Reference form≫
Next, a reference embodiment of the present invention will be described with reference to FIGS. FIG. 5 is a configuration diagram of a diluter according to the reference embodiment. FIG. 6 is a graph showing the operation and effect of the diluter according to the reference embodiment.

As shown in FIG. 5, the diluter 40C according to the reference embodiment does not include the dilution pipe 41A (see FIG. 2) for configuring the two dilution flow paths W1 and W2, but the chamber 44 (hydrogen introducing means). ), An on-off valve 45 (hydrogen introduction means), and an ECU 50 (control means, hydrogen introduction means).

  The chamber 44 is connected to the downstream side of the pipe 24c via the pipe 44b. The chamber 44 has a storage chamber 44a therein, and the anode off-gas discharged during the hydrogen purge is temporarily stored in the storage chamber 44a. That is, the chamber 44 functions as a storage container that temporarily stores the anode off gas. The volume of the storage chamber 44a is set to be larger than the amount of anode off gas discharged by the hydrogen purge.

  The downstream side of the chamber 44 joins at a connection point J2 to a pipe 32d through which a cathode off gas flows through a pipe 44c. That is, the downstream side of the chamber 44 is connected to the cathode offgas passage in the pipe 32d through which the cathode offgas flows at the connection point J2.

  The on / off valve 45 is provided on the pipe 44c, and the opening / closing of the on / off valve 45 regulates (adjusts) the flow of the anode off gas in the pipe 44c. That is, the on-off valve 45 is a valve that restricts the anode off gas stored in the chamber 44 from flowing into the pipe 32d.

  The on-off valve 45 is electrically connected to the ECU 50, and the ECU 50 opens / closes the on-off valve 45 appropriately. That is, when the ECU 50 opens the on-off valve 45, the anode off-gas in the chamber 44 is introduced into the cathode off-gas flowing through the connection point J2 through the pipe 44c according to the opening time of the on-off valve 45. ing.

  Therefore, after the hydrogen purge valve 24 is opened and the anode off gas is stored in the chamber 44, the ECU 50 opens the on-off valve 45 a plurality of times (three times in FIG. 6) as shown in FIG. By opening / closing, the anode off-gas in the chamber 44, that is, the hydrogen discharged from the fuel cell 10 can be divided into a plurality of parts and introduced into the pipe 32d through which the cathode off-gas flows, and can be sequentially diluted. And after reducing the hydrogen concentration reliably by dilution, it can exhaust. That is, when the on-off valve 45 is opened three times as shown in FIG. 6 (a), the amount of anode off-gas containing hydrogen at the measurement point Y2 downstream of the connection point J2 as shown in FIG. 6 (b). Are divided into three, and three peaks H3 corresponding to diluted hydrogen are detected.

Further, as shown in FIG. 6A, it is preferable that the times t1, t2, and t3 for opening the on-off valve 45 by the ECU 50 are set to be gradually increased. Thus, if the time t1... For opening the on-off valve 45 is gradually increased, the anode introduced into the pipe 32d at the connection point J2 even if the pressure in the chamber 44 decreases due to the discharge of the anode off-gas in the chamber 44. The amount of off-gas can be brought close to a constant value, whereby the degree of dilution of hydrogen contained in the anode off-gas can be made uniform.
In order to make the hydrogen dilution uniform, a pressure sensor is provided in the chamber 44, and the pressure in the chamber 44 and the amount of the anode off gas introduced into the pipe 32d when the on-off valve 45 is opened. The associated map data may be stored in the ECU 50, and the ECU 50 may open the on-off valve 45 based on the pressure in the chamber 44 and the map data.

  As mentioned above, although preferred embodiment of this invention was described, this invention is not limited to each said embodiment, For example, it can change as follows in the range which does not deviate from the meaning of this invention.

  In the above-described embodiment, the case where the fuel cell system S in which the diluter 40A (fuel cell exhaust gas processing device) is assembled is mounted on the fuel cell vehicle, but the usage mode of the fuel cell system is limited to this. Alternatively, for example, a stationary fuel cell system for home use may be used.

  In the diluter 40A according to the first embodiment described above, as shown in FIG. 2, the flow lengths from the branch point T1 to the pressure loss bodies 42A and 42A are set equal for the dilution flow paths W1 and W2, and the pressure loss body 42A is set. 42A, a dilution pipe 41A connected to the pipe 32d at the connection point J1 after merging at the merging point C1 having the same flow path length is provided. However, as shown in FIG. 7, for example, the flow volume V1 is small. Therefore, the branch point T2 is moved closer to the left route related to the dilution flow path W1 where the flow velocity f1 becomes higher, and the connection points J3 and J4 are connected to the pipe 32d without joining the left route and the right route related to the dilution flow path W2. It may be a diluter 40D provided with a dilution pipe 41D to be connected at. The connection point J3 related to the left route having a high flow velocity f1 is set on the upstream side of the pipe 32d relative to the connection point J4 related to the right route having a low flow velocity f2, and between the branch point T2 and the connection point J4. The flow path length passing through the left route including the dilution flow path W1 and the flow path length including the right route including the dilution flow path W2 are set to be equal.

  According to such a diluter 40D, since the flow velocity f1 downstream of the pressure loss body 42A of the left route is high, the anode off gas flowing through the left route dilution channel W1 is more than the anode off gas flowing through the right route dilution channel W2. However, it is possible to reach the cathode offgas flowing through the pipe 32d earlier in time. As a result, hydrogen in the anode off-gas that passes through the left route and hydrogen in the anode off-gas that passes through the right route are introduced into the cathode off-gas at different timings, and are diluted efficiently to reduce the hydrogen concentration. After lowering, it can be exhausted.

In the first and second embodiments described above, the case where the diluters 40A and 40B are provided with two dilution flow paths W1 and W2 has been described for the sake of clarity. However, the number of dilution flow paths is limited to this. Alternatively, it may be 3, 4, or 5. That is, the dilution pipe 41A is not limited to being branched into two branches, but may be configured to branch into three branches, four branches, five branches,.
The same applies to the diluter 40C according to the reference embodiment, and the configuration may be such that the chamber 44 and the on-off valve 45 are provided in parallel.

  In the first embodiment described above, the flow rate setting means for setting the flow rate is configured by the pressure loss body 42A provided on the inner surface of the dilution pipe 41A. However, for example, the dilution pipe 41A is partially throttled and the flow rate is set. The flow rate setting means may be configured by reducing the road cross-sectional area.

It is a figure which shows the structure of the fuel cell system which concerns on 1st Embodiment. It is a block diagram of the diluter which concerns on 1st Embodiment. It is a graph which shows the effect | action and effect of the diluter which concerns on 1st Embodiment. It is a block diagram of the diluter which concerns on 2nd Embodiment. It is a block diagram of the diluter which concerns on a reference form. It is a graph which shows the effect | action and effect of the diluter which concerns on a reference form. It is a block diagram of the diluter which concerns on a reference form .

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Fuel cell 11 Electrolyte membrane 12 Anode 24 Hydrogen purge valve 40A Diluter (exhaust gas processing apparatus of a fuel cell)
41A Dilution piping (hydrogen introduction means)
42A Pressure loss body (flow rate setting means, hydrogen introduction means)
J1 Connection point S Fuel cell system V1, V2 Channel volume W1, W2 Dilution channel

Claims (2)

A fuel cell exhaust gas treatment apparatus for diluting hydrogen discharged from an anode of a fuel cell with a diluent gas and discharging the diluted hydrogen to the outside,
Comprising hydrogen introduction means for dividing the hydrogen discharged from the anode into a plurality of dilution gas passages through which the dilution gas flows ,
The hydrogen introduction means includes
First connected to the downstream end of a discharge hydrogen flow path through which hydrogen discharged from the anode flows, branches at a branch point, joins at a junction, and connects to the dilution gas path on the downstream side of the junction. A dilution channel and a second dilution channel;
A first check valve provided in the first dilution flow path between the branch point and the junction point to prevent hydrogen backflow;
A second check valve that is provided in the second dilution flow path between the branch point and the junction point, prevents back flow of hydrogen, and has the same specifications as the first check valve;
A first pressure loss body provided in the first dilution flow path between the first check valve and the merging point and imparting a pressure loss;
A second pressure loss body that is provided in the second dilution flow path between the second check valve and the junction, and applies the same pressure loss as the first pressure loss body;
With
The channel lengths of the first dilution channel and the second dilution channel between the branch point and the junction point are equal,
The downstream flow rates of the first pressure loss body and the second pressure loss body are set to be equal,
The first A flow path volume of the first dilution flow path between the branch point and the first pressure loss body, and the second A flow of the second dilution flow path between the branch point and the second pressure loss body Equal to the volume of the road,
The second B flow path volume of the second dilution flow path between the second pressure loss body and the merge point is the first B flow of the first dilution flow path between the first pressure loss body and the merge point. Greater than road volume
Exhaust gas treatment apparatus for a fuel cell characterized by and this. A fuel cell exhaust gas treatment apparatus for diluting hydrogen discharged from an anode of a fuel cell with a diluent gas and discharging the diluted hydrogen to the outside,
Comprising hydrogen introduction means for dividing the hydrogen discharged from the anode into a plurality of dilution gas passages through which the dilution gas flows ,
The hydrogen introduction means includes
First connected to the downstream end of a discharge hydrogen flow path through which hydrogen discharged from the anode flows, branches at a branch point, joins at a junction, and connects to the dilution gas path on the downstream side of the junction. A dilution channel and a second dilution channel;
A first check valve provided in the first dilution flow path between the branch point and the junction point to prevent hydrogen backflow;
A second check valve that is provided in the second dilution flow path between the branch point and the junction point, prevents back flow of hydrogen, and has the same specifications as the first check valve;
A first pressure loss body provided in the first dilution flow path between the first check valve and the merging point and imparting a pressure loss;
A second pressure loss body provided in the second dilution flow path between the second check valve and the merging point, and applying a pressure loss larger than the first pressure loss body;
With
The channel lengths of the first dilution channel and the second dilution channel between the branch point and the junction point are equal,
The downstream flow rate of the second pressure loss body is set to be smaller than the downstream flow rate of the first pressure loss body,
The first A flow path volume of the first dilution flow path between the branch point and the first pressure loss body, and the second A flow of the second dilution flow path between the branch point and the second pressure loss body Equal to the volume of the road,
The first B flow path volume of the first dilution flow path between the first pressure loss body and the merge point, and the second B flow of the second dilution flow path between the second pressure drop body and the merge point. Equal to road volume
Exhaust gas treatment apparatus for a fuel cell characterized by and this.

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