JP2013161661A - Abnormality determination method and device of fuel electrode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To determine abnormality of a fuel electrode due to oxidation of nickel exactly in a solid oxide fuel battery, which uses methane modified as fuel gas.SOLUTION: Partial water vapor pressure in exhaust gas discharged from a fuel electrode during power generation operation of a solid oxide fuel cell is measured as a measured partial water vapor pressure. Subsequently, the measure temperature of the measured partial water vapor pressure is compared with the temperature in a region where the fuel electrode is disposed, thus calculating the effective partial water vapor pressure in that region. Thereafter, the fact that the effective partial water vapor pressure has increased 6% or more than a normal value is detected, and a determination is made that abnormality has generated in the fuel electrode.

Description

  The present invention relates to a fuel electrode abnormality determination method and apparatus for determining abnormality in a fuel electrode of a solid oxide fuel cell.

  In recent years, there has been an increasing interest in solid oxide fuel cells using oxygen ion conductors. In particular, from the viewpoint of effective use of energy, solid oxide fuel cells are not subject to the restrictions of Carnot efficiency, so they have essentially high energy conversion efficiency, and excellent environmental protection is expected. Has characteristics.

  Hereinafter, the solid oxide fuel cell will be briefly described with reference to FIG. FIG. 5 is a configuration diagram showing the configuration of the solid oxide fuel cell. The solid oxide fuel cell includes an electrolyte 501, a fuel electrode 502, and an air electrode 503. The fuel electrode 502 is supplied with a mixed gas 504 containing hydrogen gas and carbon monoxide gas as fuel, and the air electrode 503 is supplied with air 506 containing oxygen as an oxidant to perform a power generation operation. In this solid oxide fuel cell, a hydrocarbon fuel such as methane is reformed and used as a fuel gas. The mixed gas 504 supplied to the fuel electrode 502 includes, in addition to hydrogen as a fuel gas, a single gas. Carbon oxide, carbon dioxide, methane, and water vapor are mixed. In this case, hydrogen gas and carbon monoxide gas become fuel gas.

In the power generation operation, oxygen in the supplied air 506 is combined with electrons 508 at the air electrode 503 to become oxide ions (O ²⁻ ) 507. The oxide ions 507 pass through the electrolyte 501 and move to the fuel electrode 502. The oxide ions 507 moved to the fuel electrode 502 react with hydrogen in the mixed gas 504 supplied thereto to generate water (H ₂ O). At this time, electrons 508 are generated in the fuel electrode 502. The electrons 508 generated in this way are taken out from the fuel electrode 502 to the outside. The electrons 508 taken out from the fuel electrode 502 pass through the electronic load 509 and are supplied to the air electrode 503.

  The movement of the oxide ions 507 and the electrons 508 described above becomes a current in the power generation of the solid oxide fuel cell. The water (water vapor) generated at the fuel electrode 502 during power generation in this way is discharged to the outside as the fuel electrode exhaust gas 505. The fuel electrode exhaust gas 505 includes carbon dioxide and carbon monoxide generated during reforming in addition to unused hydrogen, and also includes unreformed methane. Hydrogen, carbon monoxide, carbon dioxide, methane, And a mixed gas with water vapor.

  Incidentally, the fuel electrode of a solid oxide fuel cell is generally composed of nickel and an electrolyte material. Nickel acts as a catalyst for the electrochemical oxidation reaction of hydrogen. Nickel also functions as a path (conduction path) through which electrons generated by the oxidation reaction of hydrogen are conducted.

  In addition, as shown in FIG. 6, the solid oxide fuel cell (SOFC) 601 is disposed inside the heat insulating container 605 in actual operation, and operates using heat generated by the power generation operation. The required temperature is maintained. In addition, when the temperature cannot be maintained only by heat generated by power generation, such as at the start of operation, heat is applied by an electric heater or a burner.

  During operation, a mixed gas 602 and air 604 are supplied from the outside of the heat insulating container 605 to generate power, steam generated as a result of power generation, hydrogen not used for power generation, carbon monoxide and carbon dioxide generated during reforming. A mixed gas in which carbon and non-reformed methane are mixed is discharged outside the heat insulating container 605 as the exhaust gas 603. Although not shown, air after being used for power generation is also discharged to the outside of the heat insulating container 605.

  In addition, a current is extracted from the SOFC 601 using a current extraction line 607. The extracted current is controlled by an electronic load 606 such as a variable resistor. Further, the voltage of the SOFC 601 is measured by a voltage measurement line 608 and a voltmeter 609.

Hiroaki Tagawa, “Solid Oxide Fuel Cell and Global Environment”, Agnes Jofusha Co., Ltd., 1st edition, 1st edition, pages 37-40, 1998. Kishida, S. et al., “Effect of oxide components in fuel electrode on steam degradation”, 19th SOFC Research Presentation, 162C, pp. 94-97, 2010.

  By the way, although the fuel electrode of the solid oxide fuel cell using hydrogen as a fuel has a hydrogen-steam system atmosphere, if hydrogen is insufficiently supplied during power generation, the water vapor concentration becomes high. In such an environment, nickel constituting the fuel electrode is likely to be oxidized to nickel oxide (see Non-Patent Documents 1 and 2). When nickel in the fuel electrode is oxidized to nickel oxide, the catalytic performance and conductivity are lost, and the above-described function in the electrode reaction of the fuel electrode is lost. Moreover, when nickel becomes nickel oxide, the volume expands about 1.6 times. By causing the volume expansion in this way, the electrolyte is damaged and the solid oxide fuel cell is destroyed.

  As described above, in a solid oxide fuel cell using a fuel electrode including nickel, nickel oxidation causes performance deterioration and breakage, and therefore a function to prevent nickel oxidation is necessary. Become. In order to prevent the oxidation of nickel, it is possible to quickly detect a shortage of hydrogen supply that causes an increase in water vapor concentration, and if detected, control such as stopping power generation or temporarily increasing the hydrogen flow rate. Necessary.

  In the solid oxide fuel cell described above, the voltage of SOFC 601 is monitored by a voltmeter 609, and when the voltage drops below a normal value, it is determined that hydrogen supply is insufficient, an alarm is issued, power generation is stopped, or methane gas flow rate Is temporarily increased. However, if the oxidation of nickel does not proceed to such an extent that the solid oxide fuel cell is damaged, there is a problem that the determination cannot be made due to a decrease in voltage and the sensitivity is low.

  In addition, the inventors have already proposed an abnormality determination of the fuel electrode in the solid oxide fuel cell when only hydrogen is used as the fuel gas. In this proposal, water vapor partial pressure in exhaust gas from the fuel electrode is measured. However, as described above, when a mixed gas including carbon dioxide and carbon monoxide generated during reforming in addition to hydrogen, and unreformed methane and water vapor is supplied to the fuel electrode, the cell internal temperature (800 ° C) and the water vapor partial pressure gauge temperature (about 150 ° C.), the composition of the mixed gas differs, which causes a problem that the water vapor partial pressure inside the battery cannot be measured.

  As described above, in the conventional technology, in the solid oxide fuel cell that reforms hydrocarbon fuel such as methane and uses it as the fuel gas, the abnormality of the fuel electrode due to the oxidation of nickel cannot be accurately determined with high sensitivity. There was a problem.

  The present invention has been made to solve the above-described problems. In a solid oxide fuel cell that reforms methane and uses it as a fuel gas, the abnormality of the fuel electrode due to oxidation of nickel is increased. The purpose is to enable accurate determination of sensitivity.

  The fuel electrode abnormality determination method according to the present invention includes a current value that flows to a solid oxide fuel cell when the methane gas is supplied to a solid oxide fuel cell that reforms the methane gas into a fuel gas, and the supplied A first step of determining a water vapor partial pressure in exhaust gas discharged from a fuel electrode including nickel in a solid oxide fuel cell from a flow rate of methane gas to a normal value; and a solid oxide fuel cell A second step of measuring the water vapor partial pressure in the exhaust gas discharged from the fuel electrode during power generation operation to obtain a measured water vapor partial pressure, the temperature of the exhaust gas when the measured water vapor partial pressure is measured, and the fuel electrode are arranged The third step of calculating the effective water vapor partial pressure in the region where the fuel electrode is arranged from the measured water vapor partial pressure, and the effective water vapor partial pressure increased by 6% or more from the normal value Out abnormal fuel electrode comprises a fourth step of determining that it has occurred.

  Further, the abnormality determination device for a fuel electrode according to the present invention includes a current value that flows to a solid oxide fuel cell when the methane gas is supplied to a solid oxide fuel cell that reforms methane gas into fuel gas, and a supply A normal value storage means for storing, as a normal value, a partial pressure of water vapor in exhaust gas discharged from a fuel electrode composed of nickel of a solid oxide fuel cell, which is obtained from the flow rate of the generated methane gas, and solid oxidation Measuring means for measuring the water vapor partial pressure in the exhaust gas discharged from the fuel electrode during power generation operation of the physical fuel cell, the temperature of the exhaust gas when the measured water vapor partial pressure is measured, and the temperature of the region where the fuel electrode is arranged By the calculation means for calculating the effective water vapor partial pressure in the region where the fuel electrode is arranged from the measured water vapor partial pressure, and the effective water vapor partial pressure is calculated from the normal value stored in the normal value storage means. And a determination means for detecting abnormality in the fuel electrode to determine that it has occurred that increased more than 6%.

  As described above, according to the present invention, in a solid oxide fuel cell that reforms methane and uses it as a fuel gas, it is possible to accurately determine a fuel electrode abnormality due to nickel oxidation with high sensitivity. An excellent effect is obtained.

FIG. 1 is a flowchart for explaining a fuel electrode abnormality determination method according to an embodiment of the present invention. FIG. 2 is a configuration diagram showing the configuration of the fuel electrode abnormality determination device according to the embodiment of the present invention. FIG. 3 shows the thermodynamics of the solid oxide fuel cell based on the composition of the fuel electrode exhaust gas when power is generated at an operating temperature of 800 ° C. with S / C = 3, an output current of 50 A, and a fuel utilization rate of 95%. It is a characteristic view showing the result of calculating the change in the equilibrium state of the gas composition at each temperature, assuming that there is no gas in and out by equilibrium calculation. FIG. 4 shows the time variation (a) of the deviation from the normal value of the water vapor partial pressure observed when performance degradation occurs during power generation, and the normal value of the output voltage of the solid oxide fuel cell. It is a characteristic view which shows the time change (b) of deviation | shift. FIG. 5 is a configuration diagram showing the configuration of the solid oxide fuel cell. FIG. 6 is a configuration diagram showing an operating state using the solid oxide fuel cell 601.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a flowchart for explaining a fuel electrode abnormality determination method according to an embodiment of the present invention. First, in step S101, when the methane gas is supplied to the solid oxide fuel cell that is reformed (steam reformed) to form the fuel gas, the current value that flows to the solid oxide fuel cell and the supplied methane gas From this flow rate, the water vapor partial pressure in the exhaust gas discharged from the fuel electrode configured to contain nickel of the solid oxide fuel cell is obtained and set as a normal value.

  In other words, when methane gas is supplied to a solid oxide fuel cell that reforms methane gas to form fuel gas, it can be included in the exhaust gas discharged from the fuel electrode in a normal state. The water vapor partial pressure is obtained from the value of the current flowing through the solid oxide fuel cell and the flow rate of the supplied methane gas, and stored as a normal value.

  Next, in step S102, the water vapor partial pressure in the exhaust gas discharged from the fuel electrode during power generation operation of the solid oxide fuel cell is measured to obtain a measured water vapor partial pressure. Next, in step S103, by comparing the temperature of the exhaust gas when the measured water vapor partial pressure is measured with the temperature of the region where the fuel electrode is arranged, the effective in the region where the fuel electrode is arranged from the measured water vapor partial pressure. Calculate the water vapor partial pressure. Next, in step S104, it is detected that the effective water vapor partial pressure has increased by 6% or more from the normal value, and it is determined that an abnormality has occurred in the fuel electrode.

  For example, if it is detected in step S104 that the effective water vapor partial pressure has increased by 6% or more from the normal value (Y), an alarm may be issued in step S105. Steps S102 to S104 may be repeated until it is detected that the effective water vapor partial pressure has increased by 6% or more from the normal value.

  Next, the fuel electrode abnormality determination device will be described with reference to FIG. FIG. 2 is a configuration diagram showing the configuration of the fuel electrode abnormality determination device in the present embodiment. This apparatus includes a storage unit 201, a measurement unit 202, a calculation unit 203, and a determination unit 204.

  When the methane gas 212 is supplied to the solid oxide fuel cell (SOFC) 211 that reforms the methane gas into the fuel gas, the storage unit 201 includes a fuel electrode in a normal state that includes the nickel of the SOFC 211. The water vapor partial pressure that can be included in the exhaust gas (fuel electrode exhaust gas) 213 is obtained from the current value flowing through the SOFC 211 and the flow rate of the supplied methane gas 212 and stored as a normal value. .

  The measuring unit 202 measures the water vapor partial pressure (measured water vapor partial pressure) in the exhaust gas 213 discharged from the fuel electrode during the power generation operation of the SOFC 211. The measurement part 202 is comprised from the dew point meter which measures the dew point of the waste gas 213, for example. The calculation unit 203 arranges the fuel electrode from the measured water vapor partial pressure by comparing the temperature of the exhaust gas when the measurement water vapor partial pressure measured by the measurement unit 202 is measured with the temperature of the region where the fuel electrode is arranged (inside the SOFC 211). The effective water vapor partial pressure is calculated in the region where the pressure is applied. The determination unit 204 detects that the effective water vapor partial pressure calculated by the calculation unit 203 has increased by 6% or more from the normal value stored in the storage unit 201, and has detected that an abnormality has occurred in the fuel electrode. to decide.

  The fuel electrode abnormality determination device configured as described above is, for example, a computer device including a CPU, a main storage device, an external storage device, a network connection device, and the like, and the CPU operates according to a program developed in the main storage device. By doing so, the above-described functions are realized.

  Note that the SOFC 211 to be measured and determined is disposed inside the heat insulating container 215, and maintains the temperature necessary for the operation by using the heat generated with the power generation operation. However, when the temperature cannot be maintained only by heat generated by power generation, such as at the start of operation, heat is applied by an electric heater or a burner.

  During operation, methane gas 212 and air 214 are supplied from the outside of the heat insulating container 215 to generate power, steam generated as a result of power generation and hydrogen not used, carbon dioxide and carbon monoxide generated during reforming, and A mixed gas in which unmodified methane or the like is mixed is discharged to the outside of the heat insulating container 215 as the exhaust gas 213. Although not shown, the flow rate of each gas is controlled by, for example, a mass flow controller. Further, the air after being used for power generation is also discharged to the outside of the heat insulating container 215.

  Further, a current is extracted from the SOFC 211 using a current extraction line 217. The extracted current is controlled by an electronic load 216 such as a variable resistor. Further, the voltage of the SOFC 211 is measured by a voltage measurement line 218 and a voltmeter 219.

Next, calculation of the normal value of the water vapor partial pressure will be described in more detail. The current flowing through the SOFC 211 is controlled to a constant value by the electronic load 216. Under such control, the amount of oxide ions supplied to the fuel electrode through the SOFC 211 electrolyte is half the amount of electrons flowing through the SOFC 211. Carbon oxide and hydrogen can be considered as recipients of oxide ions at the fuel electrode. For example, assuming that the ratio of carbon monoxide to be oxidized and hydrogen in the power generation reaction by the reformed gas of S / C = 3 is equal to the composition ratio thereof, H ₂ : CO = 84: 16 at 800 ° C. by thermal equilibrium calculation. Therefore, the calculated water vapor partial pressure [H ₂ O] _cal uses the hydrogen flow rate Q_H ₂ supplied into the cell, the current value I flowing in the electric circuit, and the Faraday constant F, and “[H ₂ O] _cal = {0.84 × (F / 2) × I} ÷ (Q_H ₂ ) ”. S / C represents steam / carbon, and is a molar ratio of carbon contained in the raw material hydrocarbon and water vapor added in the reaction.

However, in the above-described equation, Q_H ₂ is obtained by controlling the flow rate of methane gas with a mass flow controller and calculating the amount of hydrogen generated when the flow rate-controlled methane gas is reformed 100% at 800 ° C. by thermal equilibrium calculation. For example, if the flow rate of methane gas to be supplied (Q_CH4) is 1 mol / min at 25 ° C., the amount of hydrogen generated at 800 ° C. is 3.34 mol / min.

As described above, a calculated value of the water vapor partial pressure (discharged from the fuel electrode) at the fuel electrode of the SOFC 211 operating under a predetermined operating condition is obtained, and the normal value of the water vapor partial pressure under the operating condition ([H ₂ O] _proper).

Next, the calculation of the effective water vapor partial pressure ([H ₂ O] _present) will be described in more detail. First, the water vapor partial pressure and the gas temperature in the fuel electrode exhaust gas at the installation location of the measurement unit 202 are measured by the temperature sensor and the humidity sensor of the measurement unit 202. For example, if the temperature of the exhaust gas measured by the measuring unit 202 is 150 ° C., the water vapor partial pressure measured by the measuring unit 202 is the water vapor content when each gas component constituting the fuel electrode exhaust gas is in an equilibrium state at 150 ° C. Pressure. Therefore, it is possible to accurately calculate the effective water vapor partial pressure [H ₂ O] _present at the fuel electrode of the fuel cell that operates at a predetermined temperature by adding the change in the equilibrium state due to the temperature change to the measured water vapor partial pressure. It becomes important in control.

An example of the change of the equilibrium state due to the temperature change of each gas component constituting the fuel electrode exhaust gas is shown in FIG. Fig. 3 shows the gas flow in and out by thermodynamic equilibrium calculation based on the composition of the anode exhaust gas when power is generated at an operating temperature of 800 ° C with S / C = 3, output current 50A, and fuel utilization 95%. It is a characteristic view showing the result of calculating the change in the equilibrium state of the gas composition at each temperature, assuming that there is no gas. As shown in FIG. 3, at 150 ° C., the water vapor partial pressure is 1.06 times higher than at 800 ° C. For this reason, if the measured steam partial pressure is multiplied by 1 / 1.06, the effective steam partial pressure [H ₂ O] _present at 800 ° C. can be obtained from the measured value of the steam partial pressure at 150 ° C. .

  Hereinafter, it will be described that the above-described abnormality determination method according to the present embodiment has higher sensitivity than a conventional system that detects an abnormality by monitoring a voltage.

FIG. 4 shows the time variation (a) of the deviation from the normal value of the water vapor partial pressure in the fuel electrode exhaust gas, which is observed when performance degradation occurs during power generation, and the output voltage of the solid oxide fuel cell. The time change (b) of the deviation from the normal value is shown. (A) of FIG. 4 is the time variation of effective water vapor partial pressure and the ratio between normal value and normal value [([H ₂ O] _proper− [H ₂ O] _present) / [H ₂ O] _proper]. Is shown. FIG. 4B shows the change over time in the ratio [(V_proper−V_present) / V_proper] between the difference between the measured output voltage and the normal output voltage (normal value) and the normal output voltage. ing.

  In this observation, the fuel gas to be supplied (methane gas) is set to an amount close to the theoretical value necessary for the power generation operation, and the load is applied as an environment in which the fuel electrode easily undergoes steam oxidation. This is a state in which the water vapor concentration tends to be high and the abnormality of the fuel electrode due to nickel oxidation is likely to occur. In general, surplus fuel gas is supplied and the fuel electrode is used as a reducing atmosphere so that steam oxidation is unlikely to occur.

  If the operation of the SOFC is continued in a state where the supply amount of the fuel gas is insufficient, as shown in FIG. 4, as the fuel electrode is partially oxidized at the beginning, a certain level between the actual measured value and the normal value is obtained. It can be seen that the difference in water vapor pressure increases rapidly after a certain period of time. In the results shown in FIG. 4, the magnitude of the cell voltage deviation is about 0% and the water vapor partial pressure deviation is about 6% at the time of power generation 0 hours. First, from this, it can be said that the magnitude of the difference in water vapor partial pressure is more useful as a signal source for detecting cell abnormality more sensitively than the deviation in cell voltage.

  One of the reasons why high sensitivity can be obtained by measuring such a partial pressure of water vapor is that the partial pressure of water vapor is reduced because oxygen ions moving from the air electrode react with Ni and cannot react with hydrogen. .

  Further, after 8 hours of power generation, the magnitude of the cell voltage deviation is about 13%, while the magnitude of the water vapor partial pressure deviation is as large as 50% or more. Thus, it can be said that the magnitude of the difference in water vapor partial pressure is more useful as a signal source for detecting a cell abnormality more sensitively than the difference in cell voltage.

Further, in the result of the acceleration test shown in FIG. 4, the deviation amount of the effective water vapor partial pressure starts to increase over 6% after 3 hours have passed. This change is caused by a crack in the electrolyte layer as a result of expansion of the volume of the fuel electrode due to the progress of oxidation of the fuel electrode, and air on the air electrode side penetrates into the fuel electrode side through the crack. One possible reason is that the partial pressure of water vapor in the fuel electrode exhaust gas relatively decreased due to an increase in the partial pressure of nitrogen in the exhaust gas. Therefore, when the difference between the effective value [H ₂ O] _present of the water vapor partial pressure and the normal value [H ₂ O] _proper of the water vapor partial pressure exceeds 6%, an abnormality of the fuel electrode due to nickel oxidation occurs. It can be judged that it has started.

  This is also shown in the results shown in Table 1 below. Table 1 shows the presence or absence of nickel oxide in the fuel electrode and the presence or absence of damage to the electrolyte when the solid oxide fuel cell is analyzed in a reduced state after power generation and gradually lowered to room temperature.

  As shown in Table 1, there is no crack of nickel oxide and electrolyte in the solid oxide fuel cell in which the value of the difference ratio of water vapor partial pressure during power generation was 6% or less. On the other hand, generation of nickel oxide and cracks in the electrolyte were confirmed in the fuel cell in which the value of the difference ratio of the water vapor partial pressure exceeded 6% and became 50% during power generation.

From the above results, when the difference between the effective value [H ₂ O] _present of the water vapor partial pressure and the normal value [H ₂ O] _proper of the water vapor partial pressure exceeds 6%, the power generation is stopped or the methane gas If measures such as temporarily increasing the flow rate are taken, abnormalities can be prevented. Regarding the above-described results, the following can be considered. First, in a state where the difference ratio of the water vapor partial pressure is small, local nickel oxide is generated at the fuel electrode during power generation of the fuel cell, but if power generation is stopped, the nickel oxide is reduced by the reducing action of the fuel gas. Returning to nickel metal, the fuel electrode is restored to its original state. On the other hand, in the state where the difference ratio of the water vapor partial pressure is large, cracks occur in the electrolyte layer, and air leaks from the air electrode to the fuel electrode. In such a state, it is considered that nickel oxide is not reduced even when power generation is stopped, and naturally, cracks in the electrolyte layer are not repaired.

Furthermore, it will be described that the monitoring of the effective value [H ₂ O] _present of the water vapor partial pressure in the present invention can selectively detect the shortage of hydrogen supply.

  As described with reference to FIG. 5, the SOFC power generation principle includes the fuel electrode exhaust gas 505 containing unused hydrogen and water vapor generated by the power generation reaction. Therefore, measuring the water vapor partial pressure in the fuel electrode exhaust gas 505 is equivalent to measuring the amount of hydrogen-oxygen reaction occurring on the fuel electrode side. If the amount of carbon monoxide / oxygen reaction is assumed by the composition ratio of carbon monoxide and hydrogen, the amount of nickel-oxygen reaction occurring can be measured. Thus, according to the present invention, a shortage of supply of hydrogen to the fuel electrode is directly detected.

  As described above, according to the present invention, in the power generation operation of the solid oxide fuel cell using the reformed methane gas, the oxidation of the nickel of the fuel electrode that causes a decrease in power generation performance occurs. Therefore, it is possible to detect and judge selectively with higher sensitivity than the prior art. Based on the result of this judgment, if an appropriate measure is taken, such as issuing an alarm and stopping power generation or temporarily increasing the methane gas flow rate, the power generation performance of the solid oxide fuel cell can be maintained for a long time. It becomes possible.

  The present invention is not limited to the embodiment described above, and many modifications and combinations can be implemented by those having ordinary knowledge in the art within the technical idea of the present invention. It is obvious.

  DESCRIPTION OF SYMBOLS 201 ... Memory | storage part, 202 ... Measuring part, 203 ... Calculation part, 204 ... Judgment part, 211 ... Solid oxide fuel cell (SOFC), 212 ... Methane gas, 213 ... Exhaust gas, 214 ... Air, 215 ... Thermal insulation container, 216 ... Electronic load, 217 ... Current extraction line, 218 ... Voltage measurement line, 219 ... Voltmeter.

Claims (2)

From the current value that flows to the solid oxide fuel cell when the methane gas is supplied to the solid oxide fuel cell that reforms the methane gas into a fuel gas and the flow rate of the supplied methane gas, the solid oxide type A first step of determining a water vapor partial pressure in exhaust gas discharged from a fuel electrode configured to contain nickel of a fuel cell to a normal value;
A second step of measuring a water vapor partial pressure in exhaust gas discharged from the fuel electrode during power generation operation of the solid oxide fuel cell to obtain a measured water vapor partial pressure;
By comparing the temperature of the exhaust gas when the measured water vapor partial pressure is measured with the temperature of the region where the fuel electrode is disposed, the effective water vapor content in the region where the fuel electrode is disposed from the measured water vapor partial pressure. A third step of calculating the pressure;
A fuel electrode abnormality determination method comprising: a fourth step of detecting that the effective water vapor partial pressure has increased by 6% or more from the normal value and determining that an abnormality has occurred in the fuel electrode. . The solid oxidation obtained from the current value flowing through the solid oxide fuel cell when the methane gas is supplied to the solid oxide fuel cell by reforming the methane gas into the fuel gas and the flow rate of the supplied methane gas Normal value storage means for storing, as a normal value, a water vapor partial pressure in exhaust gas discharged from a fuel electrode configured to contain nickel of a physical fuel cell;
Measuring means for measuring a water vapor partial pressure in exhaust gas discharged from the fuel electrode during power generation operation of the solid oxide fuel cell;
By comparing the temperature of the exhaust gas when the measured water vapor partial pressure is measured with the temperature of the region where the fuel electrode is disposed, the effective water vapor content in the region where the fuel electrode is disposed from the measured water vapor partial pressure. Computing means for calculating pressure;
Determination means for detecting that the effective water vapor partial pressure has increased by 6% or more from a normal value stored in the normal value storage means and determining that an abnormality has occurred in the fuel electrode. A fuel electrode abnormality determination device.

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