JP3952456B2 - Fuel cell exhaust gas treatment device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an exhaust gas treatment device for a fuel cell, which is a power source for an electric vehicle.
[0002]
[Prior art]
When a fuel cell system serving as a power source of an electric vehicle (hereinafter referred to as “vehicle”) uses pure hydrogen (hereinafter referred to as “hydrogen”) as fuel, for example, to a fuel cell stack constituting the fuel cell system. The hydrogen supply employs a circulation system in order to increase its utilization efficiency (improve fuel efficiency) (see, for example, Patent Document 1).
As a circulation system, a blower that pressurizes hydrogen, an ejector that sucks hydrogen by generating a negative pressure, a hydrogen pump, or the like is used. In the circulatory system, if recirculation is continued for a long time, the concentration of impurities in hydrogen increases, which may reduce power generation efficiency. In addition, water may accumulate and deteriorate the flow of hydrogen in the anode piping system of the fuel cell stack.
Therefore, hydrogen or water with impurities is frequently purged when the vehicle is waiting for a signal. The purged hydrogen is discharged after being diluted to a certain concentration or less by a diluter so as not to be discharged at a high concentration.
Patent Document 1 does not disclose the idea of diluting the purged hydrogen and discharging it out of the vehicle.
[0003]
[Patent Document 1]
JP-A-6-275300 (page 4, FIG. 1)
[0004]
[Problems to be solved by the invention]
By the way, when the open / close valve of the pipe that sends purge hydrogen from the fuel cell stack to the diluter is closed due to failure during power generation, the purge hydrogen is sent to the diluter and diluted. The concentration of hydrogen discharged from the vessel becomes high. In such a case, there has been no system for detecting a malfunction of the on-off valve by detecting an abnormality in the concentration of hydrogen discharged out of the vehicle from the diluter.
[0005]
Therefore, an object of the present invention is to monitor the failure of the fuel cell stack by detecting the concentration of hydrogen discharged from the discharged fuel diluter.
[0006]
[Means for Solving the Problems]
As a means for solving the above-mentioned problems, the exhaust gas treatment device for a fuel cell according to claim 1 according to the present invention is discharged from a plurality of hydrogen discharge means of a fuel cell that is supplied with air and hydrogen gas to generate electric power. In the exhaust gas treatment apparatus for a fuel cell, the hydrogen gas retained in the retention chamber is mixed with the cathode exhaust gas discharged from the cathode of the fuel cell and then discharged outside the vehicle after dilution. A hydrogen sensor for measuring the hydrogen concentration in the discharged gas is provided, and means for detecting the presence or absence of failure of the plurality of hydrogen discharging means according to the detection value of the hydrogen sensor is provided.
[0007]
With such a configuration, in the fuel cell exhaust gas processing apparatus according to the first aspect of the present invention, when the on-off valves of the plurality of hydrogen discharge means are closed, the residence chamber (exhaust fuel diluter) If the hydrogen sensor detects hydrogen at a higher concentration than usual at the downstream side, it is possible to detect that one of the on-off valves has failed and opened by the means for detecting the presence or absence of the failure. It becomes possible to monitor whether the on-off valve has failed.
Here, the hydrogen discharge means are a purge hydrogen pipe branched from a hydrogen gas circulation system pipe of the fuel cell, an anode electrode drain pipe, a humidifier drain pipe, and the like, each having an on-off valve. .
The retention chamber is a chamber provided in the exhaust fuel diluter that retains the purged hydrogen when purging out of the vehicle the hydrogen containing impurities that are circulated and reused during power generation of the fuel cell. It is mixed with the cathode exhaust gas discharged from the cathode of the fuel cell and discharged outside the vehicle after dilution.
The cathode exhaust gas is exhaust air containing nitrogen or the like exhausted from the cathode piping system of the fuel cell.
Further, the means for detecting the presence / absence of the failure is characterized in that when the hydrogen sensor detects hydrogen having a concentration higher than a predetermined concentration, it detects that any of the plurality of hydrogen discharge means has failed. To do.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of an exhaust gas treatment apparatus for a fuel cell according to the present invention will be described below with reference to the drawings.
[0009]
In the drawings to be referred to, FIG. 1 is a diagram showing a layout of a fuel cell system box in a fuel cell electric vehicle, and FIG. 2 is a diagram of an exhaust gas treatment device for a fuel cell of the present invention.
[0010]
As shown in FIG. 1, a fuel cell system box 2 is mounted under the floor at a substantially central portion of the fuel cell electric vehicle 1. Inside the fuel cell system box 2, a fuel cell system, that is, a temperature controller 3, a fuel cell stack 4, a humidifier 5, and an exhaust fuel diluter 6 are placed in order from the front to the rear of the vehicle 1. ing. In addition to these, the fuel cell system includes a radiator (not shown) for cooling the fuel cell system box 2, a high-pressure hydrogen container, and the like.
[0011]
The fuel cell stack 4 is supplied with hydrogen as fuel stored in a high-pressure hydrogen container and air taken from the outside of the vehicle to generate electric power and supply electricity for driving the vehicle 1. In order to operate the fuel cell stack 4 suitably, the temperature controller 3 adjusts the temperature of hydrogen and air supplied to the fuel cell stack 4, and the humidifier 5 supplies hydrogen and air supplied to the fuel cell stack 4. Humidify. The discharged fuel diluter 6 releases purge hydrogen from the anode piping system and retains it, mixes it with exhaust air (cathode exhaust gas) from the cathode piping system, dilutes it, and then discharges it outside the vehicle.
[0012]
The hydrogen once used in the fuel cell stack 4 is returned to the upstream side of the humidifier 5 by a pipe 7 to form a circulation system as shown in FIG. Yes. In addition, since hydrogen that has been recirculated for a long time has a high impurity concentration, or water accumulates in the fuel cell stack 4, the hydrogen and water are purged from the circulation system pipe 7 to be purged. A purge hydrogen pipe 8 is connected to the exhaust fuel diluter 6 as a provided hydrogen discharge means. The purge hydrogen pipe 8 is provided with an open / close valve 9 that operates automatically, and is closed during normal operation and opened during purge operation.
In addition, an anode drain pipe 10 and a humidifier drain pipe 11 are connected to the exhaust fuel diluter 6 as hydrogen discharge means for discharging the anode drain of the fuel cell stack 4 and the drain of the humidifier 5. ing. The anode drain pipe 10 and the humidifier drain pipe 11 are respectively provided with on-off valves 12 and 13 that automatically operate.
[0013]
In order to exhaust the exhaust air (cathode off gas) exiting from the fuel cell stack 4 to the outside of the vehicle, a cathode pipe 14 is provided through the exhaust fuel diluter 6. Holes 17 and 17 are provided in the cathode pipe (dilution discharge part) 14 in the exhaust fuel diluter 6 to dilute and discharge hydrogen staying in a stay chamber 18 described later. Further, a hydrogen sensor 16 is provided in the cathode pipe 14 on the downstream side of the exhaust fuel diluter 6, and a cathode outlet 19 of the cathode pipe 14 is opened further downstream.
The hydrogen sensor 16 is connected to control means such as an ECU (Electronic Control Unit) 21, and the ECU 21 is connected to the on-off valves 9, 12, and 13 of the purge hydrogen pipe 8, the anode drain pipe 10, and the humidifier drain pipe 11, respectively. Then, these on-off valves 9, 12, 13 are opened and closed.
[0014]
At the upper portion of the exhausted fuel diluter 6, inlet portions 20, 20, 20 for purge hydrogen discharged from the purge hydrogen pipe 8, the anode drain pipe 10, and the humidifier drain pipe 11 are provided. The exhausted fuel diluter 6 forms a residence chamber 18 for hydrogen released from the inlet 20.
In addition, 15 is a backfire prevention filter, 25 is a drainage hole.
[0015]
The exhausted fuel diluter 6 frequently purges hydrogen mixed with impurities when the vehicle stops while waiting for a signal. By the way, when the ignition switch is turned off and the power generation of the fuel cell stack 4 is completely stopped, the flow of exhaust air (cathode off-gas) disappears, so that hydrogen that has not been discharged outside the vehicle stays in the exhausted fuel diluter 6. Become .
[0016]
The operation and effect of the exhaust gas treatment device for a fuel cell of the present invention configured as described above will be described with reference to FIG.
As shown in FIG. 2, the purge hydrogen and the drain that have entered the exhausted fuel diluter 6 by the cathode exhaust are diffused to expand the volume and stay for a while, and then the exhaust air that has a fast flow and a low pressure flows. The holes 17 and 17 and the drain holes 25 and 25 provided in the cathode pipe 14 are sucked into the cathode pipe 14, mixed with exhaust air having a high speed flowing through the cathode pipe 14, and diluted with exhaust air (cathode off-gas). ) Is discharged from the cathode outlet 19 to the outside of the vehicle as hydrogen having a predetermined low concentration (for example, a concentration of less than 1%), and the drain water is drained in the same manner .
[0017]
Therefore , the on- off valves 9, 12, and 13 shown in FIG. 2 are also closed and provided in the cathode offgas piping 14 on the downstream side of the exhaust fuel diluter 6 when power generation is performed by the fuel cell stack 4. When the hydrogen sensor 16 detects a hydrogen concentration higher than a predetermined low concentration (for example, less than 1%), the ECU 21 causes the purge hydrogen pipe 8, the anode drain pipe 10, and the humidifier drain pipe 11 to open and close the open / close valves 9. , 12 and 13 can be detected by a hydrogen sensor to detect which of the open / close valves 9, 12 and 13 is broken and opened, and if necessary, the ECU 21 instructs to issue an alarm. Or an ignition switch (not shown) can be stopped. In other words, during power generation (after power generation is stopped), when the concentration indicated by the hydrogen sensor 16 provided downstream of the discharged fuel diluter 6 is equal to or higher than a predetermined value, one of the hydrogen discharge means (open / close valves 9, 12, 13... ) Is determined to have failed.
Incidentally, in the case of the present embodiment, since it is designed not to have a hydrogen concentration higher than a predetermined value on the downstream side of the exhaust fuel diluter 6, hydrogen having a concentration higher than a predetermined value is detected downstream of the exhaust fuel diluter 6. If it is determined that the control is abnormal (valve failure, etc.).
[0018]
As described above, by providing the hydrogen sensor 16 at the downstream side of the exhaust fuel diluter 6, when also closed upstream of the on-off valve 9, 12, 13 of the emissions fuel diluter 6-off valve 9, 12 , 13 can be detected and monitored. The power generation can be stopped by the ECU 21 if necessary.
[0019]
【The invention's effect】
As described above, in the fuel cell exhaust gas treatment device according to the first aspect of the present invention, when the fuel cell stack is generating electric power and the on-off valves of the plurality of hydrogen discharge means are closed, the diluted fuel is diluted. If the hydrogen sensor detects hydrogen concentration higher than normal on the downstream side of the vessel, it can be detected that one of the on-off valves has failed and opened. It will be possible to monitor.
[Brief description of the drawings]
FIG. 1 is a diagram showing a layout of a fuel cell system box in an electric vehicle equipped with a fuel cell.
FIG. 2 is a diagram of an exhaust gas treatment device for a fuel cell according to the present invention.
[Explanation of symbols]
1: Fuel cell mounted electric vehicle (vehicle)
2: Fuel cell system box 4: Fuel cell stack 6: Exhaust fuel diluter 8: Purge hydrogen piping 9, 12, 13: Open / close valve 10: Anode drain piping 11: Humidifier drain piping 14: Cathode piping 16: Hydrogen sensor 17 : Hole 18: Retention chamber 20: Entrance 21: ECU
23: Piping for ventilation 24: Fan 26: Piping 27: Vent valve

Claims (1)

After diluting the hydrogen gas discharged from the plurality of on- off valves of the fuel cell, which are supplied with air and hydrogen gas, respectively, and stored in the retention chamber, with the cathode exhaust gas discharged from the cathode of the fuel cell In an exhaust gas treatment device for a fuel cell that is discharged outside the vehicle,
A hydrogen sensor for measuring the hydrogen concentration in the gas discharged from the residence chamber to the outside of the vehicle;
Means for detecting the presence or absence of failure of the plurality of on- off valves according to the hydrogen concentration detected by the hydrogen sensor when the plurality of on-off valves are controlled to be closed ;
Equipped with a,
The means for detecting the presence or absence of the failure is characterized in that when the hydrogen sensor detects a hydrogen concentration higher than a predetermined concentration, it detects that one of the plurality of on-off valves has failed and is open. Fuel cell exhaust gas treatment device.

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