JPH08185878A - Fuel cell power generation device - Google Patents

Abstract

PURPOSE: To surely detect the leak and permeation of reaction gases across electrodes due to the deterioration of an electrode structure during an operation of power generation. CONSTITUTION: A helium gas feed pipe 22 is connected to a fuel gas feed pipe 21 mounted on the side of a layer-built fuel cell 10 and jointed to a fuel gas feed manifold 13, thereby feeding He gases to a fuel electrode, together with fuel gases. Also, a helium gas sensor 23 is connected to an air discharge pipe 17 jointed to an air discharge manifold 12, thereby detecting the concentration of He gases leaking and permeating from the fuel electrode to an air electrode and discharged, together with the unconverted air. In addition, a He gas concentration measurement signal is sent to an arithmetic operation device 24, and an error signal is generated, when He gas concentration exceeds a reference value calculated with an operation condition accounted on the basis of the current value signal, fuel gas flowrate signal and air flowrate signal of a fuel cell power generation device, thereby detecting the leak and permeation of unconverted gases across both electrodes due to the deterioration of an electrode structure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phosphoric acid type fuel cell power generator having a function of detecting leakage and permeation of a reaction gas between a fuel electrode and an air electrode during operation.

[0002]

2. Description of the Related Art FIG. 2 is a sectional view showing a basic structure of a laminated fuel cell of a fuel cell body of a phosphoric acid type fuel cell power generator which has been conventionally used. A fuel electrode 4 comprising an electrolyte matrix 1 containing phosphoric acid as an electrolyte body and a fuel electrode base material 3 having a fuel gas flow groove 3a and a fuel electrode catalyst layer 2.
And the air electrode base material 6 having the air flow groove 6a and the air electrode 7 composed of the air electrode catalyst layer 5, the side surface of the single cell is hermetically held by the sealing material 9, and the separator 8 And a cooling plate (not shown) are appropriately inserted and laminated to form a laminated fuel cell. In this configuration, when the fuel gas is passed through the fuel gas flow groove 3a and the air is passed through the air flow groove 6a, a DC power is generated between the electrodes due to the electrochemical reaction.

Also in the phosphoric acid type fuel cell power generator using the laminated fuel cell thus constructed, the electrode structure is deteriorated with the progress of the power generation operation, for example, the separator 8 serving as a partition plate for both electrodes. When the electrolyte matrix 1 is damaged, the electrolyte matrix 1 is damaged, the characteristics of the sealing material 9 are deteriorated, or the phosphoric acid contained in the electrolyte matrix 1 is deficient, the reaction gas leaks and permeates between both electrodes, resulting in a decrease in output voltage. Moreover, since electric energy generated by the power generation reaction inside each electrode is locally consumed, local heating occurs and the structural material is thermally damaged. Therefore, in the fuel cell power generator, it is necessary to detect the presence / absence of leakage and permeation of the reaction gas between both electrodes due to the deterioration of the electrode structure, and if there is leakage / permeation, it is necessary to promptly make repairs.

FIG. 3 is a block diagram of a leak gas permeation detecting means for a reaction gas between both electrodes in a conventional fuel cell power generator. In the configuration of this figure, the fuel gas passage groove of the laminated fuel cell 10 formed by stacking the unit cells shown in FIG. 2 so that the fuel gas passage groove 3a and the air passage groove 6a are orthogonal to each other. 3a has a fuel gas supply manifold 13 and a fuel gas discharge manifold 14 on both sides having openings, and an air supply groove 6a has an air supply manifold 11 and an air discharge manifold 12 on both sides having openings. In the built-in fuel cell main body, a hydrogen gas sensor 18 is connected to an air exhaust pipe 17 that is connected to the air exhaust manifold 12 and discharges unreacted air to the outside. An oxygen gas sensor 20 is connected to a fuel gas discharge pipe 19 that discharges the fuel gas to the outside. In a normal operation in which leakage and permeation between both electrodes can be ignored, hydrogen supplied to the fuel gas supply manifold 13 as a fuel gas is discharged from the fuel gas discharge pipe 19 as unreacted fuel gas.
Oxygen in the air supplied to the air supply manifold 11 is contained in the unreacted air and is discharged from the air discharge pipe 17, but if there is leakage permeation between both electrodes, the unreacted oxygen discharged from the air discharge pipe 17 is discharged. Hydrogen will be mixed into the air, or oxygen in the air will be mixed into the unreacted fuel gas discharged from the fuel gas discharge pipe 19. Therefore, as described above, the presence / absence of leakage / transmission between both electrodes can be detected by connecting the gas sensors to both the exhaust pipes and measuring the mixed gas.

[0005]

However, even in the fuel cell power generator having the reaction gas leak permeation detecting means between both electrodes as described above, leak permeation occurs between both electrodes and the reaction gas is not generated. Even if the electrode leaks from one electrode to the other electrode, the leaked reaction gas will react and be consumed in the electrode at the leak destination. Therefore, when the amount of leakage and transmission between both electrodes is small, the amount mixed and discharged in the discharge pipe becomes extremely small as described above, and detection by the gas sensor becomes impossible. That is, the detection method according to the present configuration has a problem that detection cannot be performed unless the leak gas permeation amount becomes considerably large due to deterioration of the sealing performance of the reaction gas between both electrodes.

As a method of detecting leakage and transmission between both electrodes,
In addition to the above, there is a method of supplying nitrogen gas to the gas flow groove of either the air electrode or the fuel electrode, pressurizing the gas, and measuring the amount of leakage to the end face of the opposing electrode to detect the leakage permeation. This method has the feature that leak permeation can be detected without being hindered by the reaction inside the electrode as described above, but it is a method that can be performed only while the fuel cell power generator is stopped, and it can be detected during power generation. There is a drawback that it cannot be adopted as a method.

The present invention has been made in consideration of the above problems, and an object thereof is to prevent leakage and permeation of a reaction gas between both electrodes caused by deterioration of an electrode structure during power generation operation. It is an object of the present invention to provide a fuel cell power generator having a function of detecting accurately without being influenced by the reaction inside the cell.

[0008]

In order to achieve the above object, in the present invention, an electrolyte matrix is used, and a fuel electrode comprising a fuel electrode substrate having a fuel gas flow channel and a fuel electrode catalyst layer, and an air. A fuel gas flow groove of a laminated plate fuel cell formed by alternately stacking single cells sandwiched by an air electrode base material having a flow groove and an air electrode composed of an air electrode catalyst layer is opened. A fuel gas supply manifold and a fuel gas discharge manifold are respectively arranged on the two opposite side surfaces having a portion, and an air supply manifold and an air discharge manifold are respectively arranged on the other two side surfaces where the air flow groove has an opening, In a fuel cell power generator that supplies fuel gas to the fuel gas supply manifold and air to the air supply manifold to obtain DC power by an electrochemical reaction, A pipe that connects the pipe that supplies the inert gas to the pipe that supplies the fuel gas to the supply manifold, and that connects the detector that measures the concentration of the inert gas to the pipe that discharges the unreacted air from the air discharge manifold. , Or connect a pipe that supplies an inert gas to the pipe that supplies air to the air supply manifold,
In addition, the detector for measuring the concentration of the above-mentioned inert gas is connected to the pipe for discharging the unreacted fuel gas from the fuel gas discharge manifold.

Further, in the above fuel cell power generator, a detector for measuring the concentration of the inert gas is provided with an inert gas concentration measurement signal by the detector and a current value signal representing an operating current value of the fuel cell power generator. , The fuel gas flow rate signal indicating the fuel gas supply flow rate, and the air flow rate signal indicating the air supply flow rate are input, and the standard value of the inert gas concentration is calculated from the current value signal, the fuel gas flow rate signal, and the air flow rate signal. The calculation is performed, and the calculated standard value and the measurement value by the inert gas concentration measurement signal are compared and calculated, and the difference is connected to a calculation device having a function of outputting an abnormal signal.

Furthermore, the above detector and arithmetic unit are detachably incorporated in the fuel cell power generator. Furthermore, the above-mentioned inert gas is helium gas.

[0011]

As described above, in the laminated fuel cell of the fuel cell power generator, the pipe for supplying the inert gas is connected to the pipe for supplying the fuel gas to the fuel gas supply manifold, and the unreacted air is discharged from the air discharge manifold. Connect the detector for measuring the above-mentioned inert gas concentration to the pipe to be connected, or connect the pipe to supply the inert gas to the pipe to supply air to the air supply manifold, and not react from the fuel gas exhaust manifold. If a detector for measuring the concentration of the above inert gas is connected to the pipe for discharging the fuel gas, the inert gas sent from the pipe for supplying the inert gas is a chemically extremely stable element. Therefore, even if it is inside the battery during the power generation operation, the reaction gas is discharged without causing any reaction. That is, if there is no leakage permeation between the fuel electrode and the air electrode of the laminated fuel cell, the inert gas supplied to the pipe for supplying the fuel gas is discharged from the pipe for discharging the unreacted fuel gas, and the air is also discharged. When inert gas is supplied to the supply pipe, it will be discharged from the pipe that discharges unreacted air, but if leakage permeation occurs between the fuel electrode and the air electrode, the pipe that supplies fuel gas Part of the inert gas supplied to the air is leaked and permeated to the air electrode together with the fuel gas and discharged from the pipe that discharges unreacted air.If the inert gas is supplied to the pipe that supplies air, the Part of the gas leaks and permeates with the air to the fuel electrode and is discharged from the pipe for discharging the unreacted fuel gas. Therefore, as described above, by arranging the detector in the pipe that discharges the unreacted reaction gas from the electrode facing the electrode supplying the inert gas, and measuring the inert gas, continuous operation during power generation operation can be performed. Moreover, the leakage and permeation of the reaction gas between both electrodes can be detected without being hindered by the reaction inside the battery, and the degree of deterioration of the battery structure can be known from the amount of the leakage and permeation.

If the airtightness between the fuel electrode and the air electrode of the laminated fuel cell is completely maintained, there will be no leakage and permeation of the reaction gas between the electrodes. It is impossible to obtain high airtightness, and it is usual that there is leakage and permeation of the reaction gas even though the amount is very small. The basic amount of leakage and permeation that does not result from such deterioration of the electrode structure changes depending on the operating conditions of the laminated fuel cell, and mainly depends on the temperature conditions that are influenced by the output current, the flow rate of the supplied fuel gas, and the flow rate of air. Correspondingly fluctuates. As described above, even if there is a leak and permeation of the reaction gas between the electrodes in the laminated fuel cell, if the amount of the leak and permeation is extremely small, it does not hinder the power generation operation.

Therefore, as described above, the detector for measuring the concentration of the inert gas attached to the fuel cell power generator is
The inert gas concentration measurement signal of the detector, the current value signal of the fuel cell power generator, the fuel gas flow rate signal, and the air flow rate signal are input, and the current value signal, the fuel gas flow rate signal,
And an arithmetic unit having a function of calculating a standard value of the inert gas concentration from the air flow rate signal, comparing and calculating the calculated standard value and the measurement value of the inert gas concentration measurement signal, and outputting an abnormal signal based on the difference. If it is connected to the battery, the reference value is the leakage permeation amount between the electrodes, which is not caused by the deterioration of the battery structure corrected by taking into consideration the operating conditions, and the measured value is compared to cause the deterioration of the battery structure. The presence or absence of leakage / transmission will be detected.

Furthermore, if the above-mentioned detector and arithmetic unit are removably incorporated in the fuel cell power generator, a set of detector and arithmetic unit are sequentially attached to a plurality of fuel cell power generators, and the fuel stack is obtained. Leakage and permeation of the reaction gas between the electrodes of the battery can be evaluated. Further, if helium gas is used as the above-mentioned inert gas, helium gas is an extremely highly permeable inert gas as is commonly used for leak detection in high vacuum containers, so it is effective at leaking points. It is possible to accurately detect leakage and transmission between the electrodes.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing an embodiment of a leak permeation detecting means for a reaction gas between both electrodes in a fuel cell power generator of the present invention. Constituent parts having the same functions as those of the conventional example shown in FIG. 3 are designated by the same reference numerals, and redundant description will be omitted. The difference between this embodiment and the conventional example is that the fuel gas supply pipe 2 connected to the fuel gas supply manifold 13 is connected.
1 is connected to the He gas supply pipe 22, and the He gas sensor 23 is connected to the air exhaust pipe 17 connected to the air exhaust manifold 12 in place of the conventional hydrogen gas sensor.
Is connected, the He gas sensor 23 is connected to the arithmetic unit 24, and the oxygen gas sensor 20 connected to the fuel gas discharge pipe 19 in the conventional example.
Is not used.

When the He gas is supplied from the He gas supply pipe 22 to the laminated fuel cell 10 through the fuel gas supply pipe 21 during the power generation operation of the fuel cell power generator of the present construction, the laminated fuel cell will be operated under normal operating conditions. Since the amount of leakage from the fuel electrode to the air electrode inside 10 is extremely small, the He gas concentration detected by the He gas sensor 23 connected to the air discharge pipe 17 is extremely small, but the cell structure is When it deteriorates and the amount of leakage and permeation of the reaction gas between the fuel electrode and the air electrode increases, the amount of leakage and permeation of He gas also increases, and the concentration of He gas detected by the He gas sensor 23 also increases. The arithmetic unit 24 connected to the He gas sensor 23 uses the input current value signal, fuel gas flow rate signal and air flow rate signal of the fuel cell power generator to input the He gas sensor in a normal operating state at a predetermined He gas supply amount. The standard value of the He gas concentration at the installation position of 23 is calculated, and the He gas sensor 2
3 is a device having a function of comparing and calculating the measured value of the He gas concentration based on the He gas concentration measuring signal input from No. 3 and the standard value, and outputting an abnormal signal based on the difference. Therefore, if the battery structure deteriorates and leakage and permeation between the electrodes increase, the He gas concentration detected by the He gas sensor 23 increases, and an abnormal signal is output from the arithmetic unit 24.

In the embodiment shown in FIG. 1, the fuel gas supply pipe 21 is connected to the He gas supply pipe 22 to supply the He gas, and the air discharge pipe 17 is connected to the He gas sensor 23 to discharge the gas. Although the He concentration of the unreacted air is measured to detect the leakage permeation between the electrodes, the He gas supply pipe 22 is connected to the air supply pipe connected to the air supply manifold 11.
To supply He gas, and connect the fuel gas exhaust manifold 14 to the fuel exhaust pipe connected to the He gas sensor 23.
Even if the He concentration of the unreacted fuel gas exhausted by connecting the electrodes is measured and the leakage permeation between the electrodes is detected, it is obvious that it can be detected in the same manner.

Further, in the structure of the present embodiment, the He gas sensor 23 can be detachably attached to the air exhaust pipe 17 or the fuel exhaust pipe by a conventional technique.
By sequentially incorporating the e-gas sensor 23 and the arithmetic unit 24 into a plurality of fuel cell power generators, it is possible to detect leakage and permeation between the electrodes of the plurality of fuel cell power generators with a single device.

Further, in this embodiment, He gas is used to detect the leakage and permeation between the electrodes. However, even if other inert gas is used, the reaction inside the laminated fuel cell is similar to that of He gas. Leakage and transmission can be detected without hindrance.

[0020]

As described above, in the present invention, the two opposed fuel cells of the laminated fuel cell formed by alternately laminating the unit cells formed by sandwiching the electrolyte matrix by the fuel electrode and the air electrode are alternately laminated. The fuel gas supply manifold and the fuel gas exhaust manifold are arranged on the side surfaces, and the air supply manifold and the air exhaust manifold are arranged on the other two side surfaces.The fuel gas is supplied to the fuel gas supply manifold and the air is supplied to the air supply manifold. Supply
In a fuel cell power generator that obtains DC power by an electrochemical reaction, connect a pipe for supplying an inert gas to a pipe for supplying a fuel gas to a fuel gas supply manifold, and use a pipe for discharging unreacted air from an air discharge manifold. Connect the pipe connecting the detector for measuring the concentration of the above inert gas, or connect the pipe for supplying the inert gas to the pipe for supplying air to the air supply manifold, and connect the pipe for supplying the inert gas to the air supply manifold. Since it was decided to connect a detector for measuring the concentration of the above-mentioned inert gas to the pipe for discharging the reaction fuel gas, an inert gas that does not cause a reaction inside the laminated fuel cell is supplied together with the reaction gas,
By measuring the concentration of the inert gas in the unreacted gas discharged to the opposite electrode side with a detector, it is possible to detect the leakage permeation between the electrodes. A fuel cell power generator having a function of accurately detecting the leakage and permeation of a reaction gas in a power generation operation state without being influenced by the reaction inside the cell has been obtained.

Further, a detector for measuring the concentration of the inert gas attached to the fuel cell power generator is further provided, and further, an inert gas concentration measurement signal of the detector, a current value signal of the fuel cell power generator, and a fuel gas flow rate. Signal and air flow rate signal as input, calculate the standard value of the inert gas concentration from the current value signal, fuel gas flow rate signal, and air flow rate signal, and use the calculated standard value and the inert gas concentration measurement signal. If it is connected to an arithmetic unit that has the function of comparing and calculating measured values and outputting an abnormal signal based on the difference, the reference value is the amount of leakage and transmission between the electrodes that is not caused by deterioration of the battery structure. It is possible to obtain an accurate abnormal signal only when the deterioration of the battery structure occurs by comparing the measured value with the correction value by taking into account the deterioration of the electrode structure. Flip and the leakage transmission of the reaction gas between the electrodes, is suitable as a fuel cell power generator having a function of detecting accurately the power generating operation state.

Furthermore, if the detector and the arithmetic unit are removably incorporated in the fuel cell power generator, the set of the detector and the arithmetic unit are sequentially attached to a plurality of fuel cell power generators, and the stacks thereof are stacked. Since it is possible to evaluate the leakage and permeation of the reaction gas between the electrodes of the fuel cell, the leakage and permeation of the reaction gas between both electrodes caused by the deterioration of the electrode structure,
It is possible to obtain a fuel cell power generation device that has a function of accurately detecting the power generation operation state and that can be operated efficiently.

Further, if helium gas is used as the above-mentioned inert gas, since helium gas is an inert gas having extremely high permeability, it effectively permeates to leaking points and leaks and permeates between electrodes. Since it can be detected with high accuracy, it is more suitable as a fuel cell power generator having a function of accurately detecting the leakage and permeation of the reaction gas between both electrodes caused by the deterioration of the electrode structure in the power generation operation state. Is.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a leak permeation detecting means for a reaction gas between both electrodes in a fuel cell power generator of the present invention.

FIG. 2 is a cross-sectional view showing the basic configuration of a laminated fuel cell of a fuel cell main body of a phosphoric acid type fuel cell power generator.

FIG. 3 is a block diagram of a leak gas permeation detection means for a reaction gas between both electrodes in a conventional fuel cell power generator.

[Explanation of symbols]

 1 Electrolyte Matrix 2 Fuel Electrode Catalyst Layer 3 Fuel Electrode Base Material 3a Fuel Gas Flow Groove 4 Fuel Electrode 5 Air Electrode Catalyst Layer 6 Air Electrode Base Material 6a Air Flow Groove 7 Air Electrode 8 Separator 9 Sealant 10 Laminated Fuel Cell 11 Air supply manifold 12 Air exhaust manifold 13 Fuel gas supply manifold 14 Fuel gas exhaust manifold 15, 16 Output terminal 17 Air exhaust pipe 21 Fuel gas supply pipe 22 He gas supply pipe 23 He gas sensor 24 Computing device

Claims (4)

[Claims] 1. An electrolyte matrix comprising a fuel electrode base material having a fuel gas flow groove and a fuel electrode catalyst layer, and an air electrode base material having an air flow groove and an air electrode catalyst layer. A fuel gas supply manifold and a fuel gas discharge are provided on two opposed side surfaces of the laminated fuel cell, in which the fuel gas flow grooves have openings, respectively, which are formed by alternately stacking single cells sandwiched by A manifold is provided, and an air supply manifold and an air discharge manifold are provided on the other two side surfaces having the air flow groove having an opening, respectively, and fuel gas is supplied to the fuel gas supply manifold and air is supplied to the air supply manifold. In a fuel cell power generator that obtains DC power by an electrochemical reaction in a pipe for supplying fuel gas to the fuel gas supply manifold. A pipe for supplying active gas is connected, and a detector for measuring the concentration of the inert gas is connected to a pipe for discharging unreacted air from the air discharge manifold, or air is supplied to the air supply manifold. A pipe for supplying an inert gas is connected to the pipe, and a detector for measuring the concentration of the inert gas is connected to the pipe for discharging the unreacted fuel gas from the fuel gas discharge manifold. Fuel cell power generator. 2. The fuel cell power generator according to claim 1, wherein the detector for measuring the concentration of the inert gas displays an inert gas concentration measurement signal from the detector and an operating current value of the fuel cell power generator. A current value signal indicating the fuel gas flow rate signal indicating the fuel gas supply flow rate and an air flow rate signal indicating the air supply flow rate are input, and the current value signal, the fuel gas flow rate signal, and the air flow rate signal are inactive. It is connected to an arithmetic unit that has the function of calculating the standard value of the gas concentration, comparing the calculated standard value with the measured value of the inert gas concentration measurement signal, and outputting an abnormal signal based on the difference. Characteristic fuel cell power generator. 3. The fuel cell power generator according to claim 2, wherein the detector and the arithmetic unit are detachably incorporated. 4. The fuel cell power generator according to claim 1, 2 or 3, wherein the inert gas is helium gas.