JP2003017106A - Fuel cell control system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect the abnormality of a fuel cell whether it is serious or not, judging from the turbidity of drain water. SOLUTION: For the fuel cell control system having a fuel cell generating electricity by using hydrogen, oxygen or air, and water or vapor respectively, a turbidity meter 16a, detecting the turbidity of drain water at the outlet side of a fuel electrode of the fuel cell 1, is installed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell control system, and more particularly to a polymer electrolyte fuel cell (PEFC: Po).
Lymer Electrolyte Fuel Cell
1) A control system for detecting an abnormality during operation.

[0002]

2. Description of the Related Art Recently, the use of fuel cells as a clean power supply source for vehicles such as automobiles has become a hot topic. Here, as the fuel cell, for example, a solid polymer electrolyte membrane is sandwiched between a fuel electrode and an air electrode to form a cell,
Further, it is known that this cell is sandwiched by separators from both sides. Generally, a large number of such cells are laminated to form a unit, and a plurality of these units are further laminated to be used in a fuel cell stack state.

By the way, in a fuel cell, electric power is generally generated by a cell reaction based on a fuel such as hydrogen or oxygen (or air), but in order to operate efficiently, the state of the fuel cell must be monitored. is important. Further, it is important to detect the abnormality of the fuel cell before it becomes dangerous to humans.

Conventionally, the following method has been known as means for detecting an abnormality in a fuel cell. 1) A method of measuring the voltage of all single cells (cells) and detecting single cells that show a voltage equal to or lower than a threshold value to detect an abnormality. 2) A method of measuring a voltage with a unit in which a plurality of unit cells are connected in series and detecting a unit showing a voltage equal to or lower than a threshold value to detect an abnormality (for example, Japanese Patent Laid-Open No. 5-502973).
issue). In the case of this method 2), compared with the method 1) above,
This has the advantage that the number of measurement terminals is reduced and simplification is possible.

[0005]

However, according to the prior art, there are the following problems. In the case of 1) above,
Voltage measurement is an indirect measurement of anomalies and it is unclear what is happening internally. In other words, is it just a slight failure or malfunction, and if it can be used until repairs can be started with caution, or if it does not stop instantly will cause serious damage to the device or become a risk factor such as abnormal heat generation due to destruction. Is difficult to judge.

In the case of the above 2), even if the output is 100V, the number of unit cells is 100 and 10 and the number of voltage measuring terminals, transmission cables, and signal processing is large, so that the complexity and the influence of noise are large, It may cause malfunction.

The present invention has been made in consideration of such circumstances, and the turbidity meter for detecting the turbidity of the drain water is arranged at the fuel electrode outlet side of the fuel cell to obtain the turbidity of the drain water. It is an object of the present invention to provide a fuel cell control system capable of detecting whether the fuel cell has a slight abnormality or a serious abnormality from the degree of the above.

Further, according to the present invention, a concentration meter for detecting the concentration of exhaust gas in the exhaust gas is arranged on the fuel electrode outlet side of the fuel cell, so that the fuel cell is judged to have a slight abnormality or a serious abnormality from the exhaust gas composition in the exhaust gas. An object of the present invention is to provide a fuel cell control system capable of detecting whether there is any abnormality.

[0009]

The first invention of the present application is a fuel cell control system having a fuel cell for generating electric power by using hydrogen, oxygen or air, water or steam, respectively, and a fuel electrode outlet side of the fuel cell. The fuel cell control system is characterized in that a turbidimeter for detecting the turbidity of drain water is arranged in the fuel cell.

The second invention of the present application is to provide hydrogen, oxygen or air,
In a fuel cell control system having a fuel cell for generating power using water or water vapor, respectively, a fuel cell control characterized in that a concentration meter for detecting the concentration of exhaust gas in exhaust gas is arranged at the fuel electrode outlet side of the fuel cell. System.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in more detail below.
explain. FIG. 6 shows the solid polymer electrolyte membrane 21 with the fuel electrode 2
2, sandwich the air electrode 23 to form a single cell 24.
The single cell 24 is sandwiched between two separators 25a and 25b
It has a different structure. As shown in FIG.
As a result of trying various tests for abnormalities of various single cells,
It is estimated that the mechanism of is as shown in Fig. 4.
did. In addition, in the fuel electrode 22 of the unit cell 24 of FIG.
The phenomenon as shown in FIG.
It was estimated that the phenomenon shown in Fig. That is, burn
At the charge pole, if there is no abnormality, a normal reaction will occur,
H_TwoDeficiency, O _TwoIn case of deficiency or water retention, refer to the right column of Table 1.
Each reaction can occur. On the other hand, at the air electrode, H_TwoLack
Poor, O_TwoIn the case of deficiency or water retention, the
Each response can occur.

[0012]

[Table 1]

[0013]

[Table 2]

The causes of the above-mentioned abnormality of the single cell are, for example, H ₂ deficiency at the fuel electrode, O ₂ deficiency at the air electrode,
H ₂ deficiency due to water retention at the fuel electrode, O ₂ deficiency due to water retention at the air electrode, H ₂ generated due to them, damage to members due to combustion of O ₂ , and due to them The damages of the members that occur, the combustion of these members, the perforation of the polymer film caused by the damages, the gas leak, and the acceleration of mixed combustion are included.

FIG. 5 is a diagram in which the mechanism of damage of the single cell is estimated. When damage occurs in the fuel electrode and the air electrode (H ₂ deficiency, O ₂ deficiency, water retention), the fuel electrode The reactions shown in the right column of Table 1 may occur, and the reactions illustrated in the right column of Table 2 may occur at the air electrode.

In fact, under the condition that the gas composition, the flow rate of cooling water, the humidifying temperature of the air electrode, the humidifying temperature of the oxygen electrode, and the oxygen utilization rate are set to predetermined values, the voltage and the gas composition change with time due to fuel deficiency. When tested, the results shown in FIG. 7 were obtained. That is, the H ₂ utilization rate with respect to the test time (h), cell voltage (V), air electrode (cathode) outlet H ₂ concentration (ppm),
The relationship with the fuel electrode (anode) outlet O ₂ concentration (%) is as shown in FIG. 7. From FIG. 7, at the time of H ₂ deficiency (H ₂ utilization rate 200%), the H ₂ concentration in the air outlet gas increased from 80 ppm to 1000 ppm in response to the change in the cell voltage, and the O ₂ concentration in the fuel electrode outlet gas increased. Is 0% (detection limit 10
(ppm) to 5% was confirmed.

When the single cell was tested with holes, the results shown in FIGS. 8, 9 and 11 were obtained. Here, FIG. 8, the differential pressure - is a characteristic diagram showing the (air fuel) and the gas on the fuel electrode side _{(N 2, O 2, CO} 2, H 2) the relationship between the change in concentration of the composition. On the other hand, FIG. 9 is a characteristic diagram showing the relationship between the hole area and the concentration change on the fuel electrode side. Figure 11
FIG. 4 is a characteristic diagram showing a relationship between a hole position (distance from inlet / total length of flow path) and gas composition (%) on the fuel electrode side.

From FIG. 8, it was revealed that air leaks from the air electrode side to the fuel electrode side, whereby the gas composition on the fuel electrode side changes and can be detected. Note that, in FIG. 8, CO ₂ and H ₂ are N ₂ and O as the pressure difference increases.
_It decreases by the amount that ₂ increases. Further, it is apparent from FIG. 9 that the change in O ₂ concentration on the fuel electrode side is larger when the pressure difference is larger than when the pressure difference at the fuel electrode outlet is small. Further, it can be seen from FIG. 11 that the gas concentration varies depending on the position of the hole. This indicates that hydrogen and oxygen are mixed and burned due to the presence of the electrode catalyst, but the burning rate differs depending on the position of the hole.

In the present invention (first invention), a turbidimeter for detecting the turbidity in the drain water is arranged at the fuel electrode outlet side of the fuel cell. This is effective in that the drain becomes black at the outlet side of the fuel electrode due to. That is, by measuring the turbidity of the drain, it can be confirmed that the phenomenon in which the carbon powder or the metal powder (catalyst) that is the electrode constituent material on the fuel electrode side flows out due to damage can be detected. For example, the relationship between time, turbidity, and voltage is as shown in FIG. However, the current is constant as shown in FIG.

There are two points to be noted here.
The first point is that the turbidity change is detected earlier than the voltage change. In other words, it means that severe damage has already occurred when the voltage change is sensed, and it can be said that the turbidity measurement is highly sensitive to the detection of a serious abnormality. The second point is that a serious abnormality called electrode damage can be discriminated and detected. That is, there are voltage changes in the fuel cell due to changes in operating conditions such as an increase in resistance due to drying of the polymer membrane and changes in fuel gas composition, but these can be easily recovered by fine adjustment of operating conditions. Since it is not a permanent deterioration, it can be said that the turbidity measurement can discriminate and recognize a serious abnormality that occurs inside the battery that cannot be recognized by the voltage measurement, regardless of safety and device life.

In the present invention (second invention), a concentration meter for detecting the concentration in the exhaust gas is arranged at the fuel electrode outlet side of the fuel cell. As the concentration meter, for example, oxygen for detecting the oxygen concentration in the exhaust gas is used. A densitometer is mentioned. The densitometer is generally provided on the fuel electrode outlet side of the fuel cell, but it may be provided not only on the fuel electrode outlet side of the fuel cell but also on the air electrode outlet side.

In the present invention, it is preferable to have a control circuit that outputs a warning signal when the turbidity measured by the turbidimeter is abnormal and an operation stop signal when the turbidity is seriously abnormal. As a result, the fuel cell is not destroyed, and it is possible to avoid exposing humans to a dangerous state.

In the present invention, it is preferable to have a central control center to which detailed data such as temperature, pressure, gas flow rate, etc. are transmitted in addition to the warning signal and the operation stop signal, and the information is preferably analyzed. As a result, a vehicle equipped with the fuel cell or the like can be remotely controlled based on more accurate data.

In the present invention, a turbidimeter for detecting the turbidity of drain water is provided on the fuel electrode outlet side of the fuel cell, and a densitometer (D, for example, oxygen concentration meter) for detecting the concentration in exhaust gas (for example, oxygen concentration). ) Is provided to create an abnormal signal detection map showing the relationship between turbidity and concentration.
For example, as shown in FIG. 12, this map has O ₂ on the horizontal axis.
The change in concentration is shown, and the vertical axis shows the turbidity. When an attention signal is issued according to these values (in the case of a micro hole), an alarm signal is issued (H ₂ deficiency, water retention), an instantaneous interface is displayed. This is divided into the case where a lock signal is issued (burnout, hole drilling). With this, it is possible to confirm specifically how much abnormality has occurred in the fuel cell.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A fuel electrode control system according to each embodiment of the present invention will be described below with reference to the drawings.

Example 1 Reference is made to FIG. Reference number 1 in the figure indicates a reformer including an evaporation unit 2, a reforming unit 3, and a CO removing unit 4. The reformer 1 is provided with a tank 6a containing methanol 5 as a liquid fuel and a tank 6b containing water 7. Both tanks 6a, 6b and the reformer 1 are provided with a pump 8
a, a pipe 10 provided with a flow rate controller 9a, and a pump 8
b, a pipe 11 having a flow rate adjuster 9b interposed therebetween, and a pipe 12 connected to these two pipes 10, 11. Gasification is performed in the evaporator 2 of the reformer 1.
Further, in the reforming section 3, a steam reforming reaction is carried out with methanol 4 and water 7 to obtain a hydrogen rich gas. Furthermore,
A catalyst that selectively oxidizes only CO is arranged in the CO removal unit 4, and the CO that has passed through the CO removal unit 4 is reduced to, for example, 10 ppm or less.

A solid polymer fuel cell 13 having a fuel electrode and an oxygen electrode is connected to the reformer 1 through a pipe 14. Here, the fuel cell 13 functions as a drive source of the motor 15. A turbidity meter 16a and an oxygen concentration meter 17 are arranged at the fuel electrode outlet of the fuel cell 13, and a turbidity meter 16b is arranged at the oxygen electrode outlet of the fuel electrode 13.
Reforming unit 3, CO removing unit 4 and fuel cell 1 of the reformer 1.
Air is supplied to blower 3 from blower 18. Here, flow rate controllers 9c, 9d, and 9e are provided in the pipes in the middle of sending the air, respectively.

The gas mainly containing hydrogen from the pipe 14 is supplied to the fuel electrode of the fuel cell 13, and the air passing from the blower 18 through the flow rate controller 9e is supplied to the oxygen electrode of the fuel cell 13. Further, hydrogen, oxygen, etc. remaining in the fuel cell 13 are sent to the evaporation unit 2 of the reformer 1. The flow rate controllers 9a, 9b, 9c, 9d, 9e and the turbidimeters 16a, 16b.
A controller 19 is electrically connected to each of the oxygen concentration meters 17 and. Here, the controller 19 controls the turbidimeter 16
a, 16b and the oxygen concentration meter 17 detect an abnormality, issue an alarm and an interlock operation signal, and in response to this signal, the amount of methanol, water, air to each flow rate controller 9a-9e or the opening / closing of each valve. Is adjusted.

That is, the controller 19 electrically connected to the turbidimeters 16a and 16b and the oxygen concentration meter 17 constitutes a control circuit together with the flow rate controllers 9a to 9e.
When the turbidity due to 6a and 16b and the concentration due to the oxygen concentration meter 17 are abnormal, a warning signal is issued, and when there is a serious abnormality, an operation stop signal is issued.

As described above, in the first embodiment, the turbidity meter 16a and the oxygen concentration meter 17 attached to the fuel electrode outlet of the fuel cell 13 and the turbidity meter 16b attached to the air electrode outlet.
Thus, the abnormality of the cell is detected and diagnosed, and the operating condition of the reformer 1 is changed or stopped.

Further, by using the turbidity based on the turbidimeter 16a and the oxygen concentration based on the oximeter 17, an abnormal signal detection map showing the relationship between the turbidity and the concentration is prepared as shown in FIG. Depending on the value of, the warning signal is output (for minute holes), the alarm signal is output (H ₂ deficiency, water retention), or the interlock signal is output instantaneously (burnout, perforation). For example, it is possible to confirm specifically how much abnormality has occurred in the fuel cell.

(Embodiment 2) Referring to FIG. However, in FIG.
The same members as and are denoted by the same reference numerals, and description thereof will be omitted. Example 2
Is characterized in that a turbidimeter 16a is provided at the fuel electrode outlet of the fuel cell 13 and a turbidimeter 16b is provided at the air electrode outlet as compared with the first embodiment. According to Example 2, Turbidimeter 1
The presence of 6a and 16b makes it possible to detect whether the fuel cell has a slight abnormality or a serious abnormality based on the degree of turbidity of the drain water.

(Embodiment 3) Referring to FIG. However, in FIG.
The same members as and are denoted by the same reference numerals, and description thereof will be omitted. Example 3
In comparison with Example 1, an oxygen concentration meter 17 is provided at the fuel electrode outlet of the fuel cell 13, and a turbidity meter 16b is provided at the air electrode outlet.
Is provided. According to the third embodiment, the presence of the oxygen concentration meter 17 indicates the oxygen concentration in the exhaust gas, and the presence of the turbidity meter 16b indicates the degree of turbidity of the drain water. Can be detected.

In the above embodiment, the case where liquid fuel (methanol) and water are sent to the fuel cell through the reformer has been described, but the present invention is not limited to this. For example, without using a reformer, hydrogen (gas fuel) oxygen (or air), water (or steam)
Together with this, it may be sent directly to the fuel cell to generate power.

[0035]

As described above in detail, according to the present invention, the turbidity meter for detecting the turbidity of the drain water is arranged at the fuel electrode outlet side of the fuel cell, whereby the turbidity of the drain water is It is possible to provide a fuel cell control system capable of detecting whether the fuel cell has a slight abnormality or a serious abnormality based on the degree of the above.

Further, according to the present invention, a concentration meter for detecting the concentration of the exhaust gas in the exhaust gas is arranged on the fuel electrode outlet side of the fuel cell, so that the fuel cell shows a slight abnormality from the exhaust gas composition in the exhaust gas. It is possible to provide a fuel cell control system capable of detecting whether the abnormality is a serious abnormality.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a fuel cell control system according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a fuel cell control system according to a second embodiment of the present invention.

FIG. 3 is an explanatory diagram of a fuel cell control system according to a third embodiment of the present invention.

FIG. 4 is an explanatory view of an abnormal mechanism in a polymer electrolyte fuel cell (PEFC).

FIG. 5 is an explanatory diagram of a damage mechanism in PEFC.

FIG. 6 is an explanatory diagram showing a reaction state of each gas and water in PEFC.

FIG. 7 is a characteristic diagram showing the relationship between test time in PEFC and H ₂ utilization rate, cell voltage, cathode outlet H ₂ concentration, and anode outlet O ₂ concentration.

FIG. 8 is a characteristic diagram showing the relationship between the differential pressure (air-fuel) and the concentration change of each gas on the fuel electrode side in PEFC.

FIG. 9 is a characteristic diagram showing the relationship between the hole area and the change in the concentration of O ₂ gas on the fuel electrode side in PEFC.

FIG. 10 is a characteristic diagram showing the relationship between time, turbidity, and voltage in PEFC.

FIG. 11 is a characteristic diagram showing the relationship between the hole position and the gas composition on the fuel electrode side in PEFC.

FIG. 12 is an explanatory diagram of an abnormal signal detection map by O ₂ concentration change and turbidity in PEFC.

[Explanation of symbols]

1 ... reformer, 2 ... Evaporator, 3 ... reforming section, 4 ... CO removal unit, 5 ... methanol, 6a, 6b ... tank, 7 ... water 9a-9e ... Flow rate controller, 13 ... Fuel cell, 16a, 16b ... Turbidimeter, 17 ... Oxygen meter, 18 ... Blower 19 ... Controller.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Eiki Ito             4-6-22 Kannon Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture               Mitsubishi Heavy Industries Ltd. Hiroshima Research Center (72) Inventor Tamotsu Yamada             4-6-22 Kannon Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture               Mitsubishi Heavy Industries Ltd. Hiroshima Research Center (72) Inventor Akio Sato             4-6-22 Kannon Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture               Mitsubishi Heavy Industries Ltd. Hiroshima Research Center (72) Inventor Shigeru Tsurumaki             1-8 Koura, Kanazawa-ku, Yokohama-shi, Kanagawa               Mitsubishi Heavy Industries, Ltd. Basic Technology Research Center F-term (reference) 5H026 AA06                 5H027 AA06 KK31

Claims (7)

[Claims] 1. A fuel cell control system having a fuel cell for generating electric power using hydrogen, oxygen or air, water or water vapor, respectively, and a turbidity for detecting turbidity of drain water at a fuel electrode outlet side of the fuel cell. A fuel cell control system in which a meter is arranged. 2. A control circuit for outputting a warning signal when the turbidity measured by the turbidimeter is abnormal, and an operation stop signal when the turbidity is seriously abnormal. Fuel cell control system. 3. In addition to the warning signal and the operation stop signal, the temperature,
3. The fuel cell control system according to claim 2, further comprising a central control center for transmitting detailed data of pressure and gas flow rate, and analyzing such information. 4. A fuel cell control system having a fuel cell for generating electric power using hydrogen, oxygen or air, water or water vapor, respectively, and a densitometer for detecting exhaust gas concentration in exhaust gas at a fuel electrode outlet side of the fuel cell. A fuel cell control system characterized in that a fuel cell control system is provided. 5. The fuel cell control system according to claim 4, wherein the concentration meter is an oxygen concentration meter. 6. A control circuit for outputting a warning signal when the concentration measured by the densitometer is abnormal, and an operation stop signal when the concentration is seriously abnormal. The fuel cell control system described. 7. A warning signal, an operation stop signal, a temperature,
7. The fuel cell control system according to claim 6, further comprising a central control center for transmitting detailed data of pressure and gas flow rate, and analyzing such information.