JP5333713B2 - A fuel cell system, a program used for the fuel cell system, and an information recording medium. - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To remove carbon and moisture content precipitated in an electrode during power generation while achieving miniaturization and improving durability. <P>SOLUTION: A fuel cell system has a fuel cell that generates electric power by flowing hydrocarbon gas and air so as to be in contact with a fuel electrode and an air electrode of a solid electrolyte cell. The system includes a first flow rate control section for controlling distribution of the hydrocarbon gas by increasing or decreasing its amount, a second flow rate controlling section for controlling distribution of air by increasing or decreasing its amount, and a gas concentration detecting section for detecting the concentration of the hydrocarbon gas, and further includes first supply stop means 50A for stopping only the supply of the hydrocarbon gas, gas concentration determining means 50B for determining whether the concentration of the hydrocarbon gas detected by the gas concentration detection section 10 is reduced to a predetermined value or less, and second supply stop means 50C for stopping the supply of air when it is determined that the concentration of the hydrocarbon gas is reduced to a predetermined value or less. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a fuel cell system that generates power from a fuel cell using a solid electrolyte cell, a program used for the fuel cell system, and an information recording medium.

Conventionally, there is a fuel cell system configured as disclosed in Patent Documents 1 and 2.
A fuel cell system disclosed in Patent Document 1 includes a first solid oxide electrolyte, a first electrode provided on one side of the first solid oxide electrolyte, and fuel supplied to the first electrode. A first fuel flow path, a second electrode provided on the other side of the first solid oxide electrolyte, a first oxidant flow path for supplying an oxidant to the second electrode, and the first electrode An electrochemical treatment unit including a power supply unit capable of applying a potential having the first electrode as a positive electrode between the second electrode and the second electrode; a second solid oxide electrolyte; and the second solid oxide An anode provided on one side of the shaped electrolyte, a second fuel flow path for supplying fuel to the anode, a cathode provided on the other surface of the second solid oxide electrolyte, and an oxidant on the cathode And a solid oxide fuel cell having a power generation unit provided with a second oxidant flow path to be supplied. It is obtained by the content that the fuel discharged from said first fuel flow path is supplied to the second fuel passage.
In other words, an attempt is made to prevent damage to the electrode due to residual gas by purging with a gas obtained by adding a reducing gas to an inert gas at the time of stopping.

In the fuel cell system disclosed in Patent Document 2, the battery cell electrolyte is formed of ionic conductive ceramics, and the electricity between the fuel gas supplied to the fuel electrode of the battery cell and the oxygen supplied to the air electrode of the battery cell. A solid oxide fuel cell main body that generates DC power by a chemical reaction, and oxygen obtained by separating air into nitrogen and oxygen during operation of the solid oxide fuel cell main body is used as the air electrode of the battery cell. An air separation device to be supplied, a liquid nitrogen storage tank for storing nitrogen separated by the air separation device as liquid nitrogen, and the battery by nitrogen separated by the air separation device during operation of the solid oxide fuel cell A battery cell cooling facility for cooling the cell, and supplying nitrogen stored in the liquid nitrogen storage tank to the fuel electrode of the battery cell when the solid oxide fuel cell is shut down Is obtained by a fuel electrode nitrogen supply equipment.
That is, N2 generated by the air separation device is used and supplied to the fuel electrode when stopped.
JP 2003-243000 A JP 2004-220942 A

  However, the fuel cell systems described in Patent Documents 1 and 2 have a problem that the system size is large and the manufacturing cost is high in any configuration.

  Accordingly, the present invention provides a fuel cell system, a program used for the fuel cell system, and an information recording medium capable of removing carbon and moisture deposited on the electrode while reducing power generation while continuing power generation while reducing the size. The purpose is to provide.

In order to solve the above problems, a fuel cell system according to the present invention includes a fuel cell that generates power by flowing a hydrocarbon gas and air into a fuel electrode and an air electrode of a solid oxide cell, respectively, and the carbonization described above. A first flow rate adjusting unit for adjusting the flow rate of hydrogen gas, a second flow rate adjusting unit for adjusting the flow rate of the air, a gas concentration detecting unit for detecting the concentration of the hydrocarbon gas, And an oxygen partial pressure measuring unit for measuring the oxygen partial pressure of the hydrocarbon gas.
In the present invention, the concentration of the hydrocarbon gas detected by the first supply stop means for stopping only the supply of the hydrocarbon gas through the first flow rate adjustment unit and the gas concentration detection unit is a predetermined value or less. When the gas concentration determination means and the gas concentration determination means determine that the concentration of the hydrocarbon gas has decreased to a predetermined value or less, the air concentration is reduced via the second flow rate adjustment unit. A second feed stop means for stopping the feed, a feed start means for starting the supply of electric power of the opposite polarity to the fuel electrode and the air electrode after the air feed is stopped, and an oxygen content When the oxygen partial pressure determination means for determining whether or not the oxygen partial pressure measured by the pressure measurement unit has become a predetermined value or less and the oxygen partial pressure determination means have determined that the oxygen partial pressure has become a predetermined value or less, Reverse polarity power supplied to fuel and air electrodes And a power supply stop means for stopping.

A program used in a fuel cell system according to the present invention for solving the above-described problem is a fuel that generates power by flowing a hydrocarbon gas and air into a fuel electrode and an air electrode of a solid electrolyte cell, respectively. A battery, a first flow rate adjusting unit for adjusting the flow rate of the hydrocarbon gas, a second flow rate adjusting unit for adjusting the flow rate of the air, and a gas for detecting the concentration of the hydrocarbon gas The fuel cell system is provided with a concentration detection unit and an oxygen partial pressure measurement unit that measures the oxygen partial pressure of hydrocarbon gas.
In the present invention, whether or not the hydrocarbon gas concentration detected by the gas concentration detection unit has decreased to a predetermined value or less, and the function of stopping only the supply of hydrocarbon gas via the first flow rate adjustment unit. And a function for stopping air supply via the second flow rate adjustment unit when the gas concentration determination means determines that the concentration of the hydrocarbon gas has decreased to a predetermined value or less. After the supply of gas is stopped, the function of starting the supply of electric power of the opposite polarity to the fuel electrode and the air electrode, and whether or not the oxygen partial pressure measured by the oxygen partial pressure measuring unit has become a predetermined value or less The fuel cell system is controlled by a function for determining whether or not the partial pressure of oxygen supplied to the fuel electrode and the air electrode is stopped when it is determined that the oxygen partial pressure has become a predetermined value or less. Characterized by being realized in a computer That.

  An information recording medium according to the present invention for solving the above-described problems is characterized in that a program used for the fuel cell system described above is recorded.

  ADVANTAGE OF THE INVENTION According to this invention, while aiming at size reduction, while being able to remove the carbon and water | moisture content which precipitated on the electrode, continuing electric power generation, durability can be improved.

  The best mode for carrying out the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the overall configuration of the fuel cell system according to the first embodiment of the present invention, and FIG. 2 is a block diagram showing the function of the controller unit.

  As shown in FIG. 1, a fuel cell system A1 according to the first embodiment of the present invention includes a fuel cell B, a controller unit C, an oxygen partial pressure measurement unit P, and an ammeter 10 as a gas concentration detection unit according to an example. The power storage unit 20 and the flow rate adjustment units 30I, 30O, 31I, and 31O have a main hardware configuration.

In the fuel cell B, a solid electrolyte type cell 40 in which a fuel electrode 41 and an air electrode 42 are opposed to both sides of an electrolyte 43 is accommodated in a case (not shown).
Electric power is generated by flowing one gas to the fuel electrode 41 and air to the air electrode 42. In the present embodiment, one gas is a hydrocarbon gas, and the other gas is air.

  In the fuel cell B, an inflow path 11 for allowing hydrocarbon gas to flow toward the fuel electrode 41, an inflow path 12 for allowing air to flow toward the air electrode 42, and a hydrocarbon in flow contact with the fuel electrode 41 An outflow passage 13 for letting out gas and an outflow passage 14 for letting out the air flowing in contact with the air electrode 42 are provided.

  The oxygen partial pressure measuring unit P is disposed in the inflow path 11 and measures the oxygen partial pressure of the hydrocarbon gas flowing through the inflow path 11.

  The ammeter 10 as a gas concentration detection unit measures the gas concentration as an output current. That is, when the fuel cell B is generating power in the constant voltage operation mode, the decrease in gas concentration is proportional to the decrease in output current. Therefore, an attempt is made to detect the gas concentration by measuring the output current.

  The flow rate adjusting units 30I, 30O, 31I, and 31O include an on-off valve 32 disposed in the inflow passages 11 and 12 and the outflow passages 13 and 14, respectively, and a valve drive unit that opens and closes the on-off valve 32 (none shown). And is opened and closed by a drive signal output from a controller unit C, which will be described in detail later, and can feed and stop hydrocarbon gas and air flowing through each flow path. (See FIG. 2).

That is, the flow rate adjusting unit 30I is disposed in the inflow channel 11, the flow rate adjusting unit 30O is disposed in the outflow channel 13, the flow rate adjusting unit 31I is disposed in the inflow channel 12, and the flow rate adjusting unit 31O is disposed in the outflow channel 14, respectively.
In the present embodiment, the flow rate adjustment unit 30I and the flow rate adjustment unit 30O are the first flow rate adjustment unit for adjusting the flow rate of the hydrocarbon gas, the flow rate adjustment unit 31I and the flow rate adjustment unit 31O are air. It is the 2nd flow volume adjustment part for carrying out increase / decrease adjustment of the distribution | circulation amount of.
The first flow rate adjustment unit may be either the flow rate adjustment unit 30I or the flow rate adjustment unit 30O. Similarly, the second flow rate adjustment unit may be the flow rate adjustment unit 31I or the flow rate adjustment unit 31O. Either of them may be used.

  The power storage unit 20 stores surplus power when the fuel cell B is in steady operation, and is a secondary battery in the present embodiment, but a capacitor or the like may be employed in addition to this. it can.

  As shown in FIG. 2, the controller unit C includes a controller 50 including a CPU (Central Processing Unit), an interface circuit, and the like, and a storage unit 51 including a hard disk as an information recording medium. By executing the program used for the fuel cell system stored in 51, the following functions are exhibited.

The program used for the fuel cell system A1 includes the first feed stop function for stopping only the feed of hydrocarbon gas via the first flow rate adjusting unit 30I, and the hydrocarbon gas detected by the gas concentration detector 10. A determination function for determining whether or not the concentration of the hydrocarbon gas has decreased to a predetermined value or less, and when it is determined that the concentration of the hydrocarbon gas has decreased to a predetermined value or less, the air flow is sent via the second flow rate adjustment unit 31I. The second supply stop function for stopping the supply is realized in a computer that controls the fuel cell system A1.
In the present embodiment, the controller unit C is a computer that controls the fuel cell system A1.

(1) A function of stopping only the supply of hydrocarbon gas via the first flow rate adjusting unit 30I. This is referred to as “first feeding stop means 50A”.
The timing for stopping only the supply of the hydrocarbon gas is when it is determined to stop the operation of the fuel cell B. Specifically, for example, when an operation stop signal is transmitted to the controller unit C from the outside.

Therefore, it is determined whether or not to stop the operation of the fuel cell B, and when it is determined to stop the operation, only the supply of hydrocarbon gas is stopped via the first flow rate adjustment unit 30I. Also good.
A function for determining whether or not to stop the operation of the fuel cell B is referred to as an operation stop determination means.

(2) A function of determining whether or not the concentration of the hydrocarbon gas detected by the gas concentration detection unit 10 has decreased to a predetermined value or less. This is referred to as “gas concentration determination means 50B”.
That is, as the concentration of the remaining fuel gas decreases, the current value also decreases proportionally. Therefore, in this embodiment, when the current value becomes a predetermined value or less, in other words, the hydrocarbon gas disappears. It is determined whether or not the current value is sometimes equal to or less.

(3) A function of stopping the supply of air via the second flow rate adjusting unit 31I when the gas concentration determination means 50B determines that the concentration of the hydrocarbon gas has decreased to a predetermined value or less. This is referred to as “second feeding stop means 50C”.

(4) A function of performing constant voltage operation of the fuel cell B after stopping the supply of hydrocarbon gas. This is referred to as “constant voltage operation means 50D”.
“After stopping the supply of hydrocarbon gas” is after stopping the supply of air via the second flow rate adjusting unit 31I. Further, when the gas concentration determination means 50B determines that the concentration of the hydrocarbon gas has decreased to a predetermined value or less, the air supply is stopped via the second flow rate adjustment unit 31I. May be.

(5) A function of starting the supply of electric power having the opposite polarity to the fuel electrode and the air electrode after the air supply is stopped. This is referred to as “power supply starting means 50E”.
The power supply unit 20 is used as a power source for the power supply.
The supply of electric power may be started when the gas concentration determination means 50B determines that the concentration of the hydrocarbon gas has decreased to a predetermined value or less.

(6) A function of determining whether or not the oxygen partial pressure measured by the oxygen partial pressure measuring unit P has become a predetermined value or less. This is referred to as “oxygen partial pressure determination means 50F”.
The “predetermined value” is a pressure corresponding to the end of electrolysis.

(7) A function of stopping the reverse polarity power supplied to the fuel electrode and the air electrode when the oxygen partial pressure determination means 50F determines that the oxygen partial pressure has become a predetermined value or less. This is referred to as “power supply stopping means 50G”.
Ni, which is the main component of the fuel electrode, is oxidized by oxygen and decreases in activity, or the power generation characteristics and durability of the electrode decrease due to volume expansion. Further, the limit of the oxygen partial pressure to be oxidized varies depending on the operating temperature, but is, for example, 10 to 14 atm at 800 degrees.
Therefore, if the operating temperature is known, a predetermined allowable oxygen partial pressure range is determined. If it is within that range, it is not necessary to perform the electrolysis, and if it exceeds, the electrolysis reaction is started.

The operation of the fuel cell system A1 having the above configuration will be described with reference to FIG. FIG. 3 is a flowchart showing the operation stop mode of the fuel cell system A1.
When the operation of the fuel cell B is stopped, the process proceeds to step S1.

Step S1: Only the hydrocarbon gas is stopped via the flow rate adjusting unit 30I, and the process proceeds to Step S2. At this time, air is kept flowing.
Step S2: The power generation is continued in the constant voltage operation mode in which the output voltage is constant, and the process proceeds to Step S3. At this time, the electric power generated by the hydrocarbon gas remaining in the fuel cell B is stored in the power storage unit 20.

Step S3: Check the output current and proceed to Step S4.
Step S4: It is determined whether or not the output current has decreased below a predetermined value. If the output current has decreased below the output current, the process proceeds to step S5, and if not, the process returns to step S2.

Step S5: Stop the air supply via the second flow rate adjusting unit 31l and proceed to Step S6.
Step S6: Electricity is generated by supplying reverse polarity electric power whose direction of current is reversed from that during power generation, and the process proceeds to step S7.
That is, by electrolyzing H ₂ O (moisture) contained in the hydrocarbon gas, oxidation of the fuel electrode (Ni) by H ₂ O is prevented, and a decrease in reaction activity of the fuel electrode is prevented.
Since the theoretical decomposition voltage of H ₂ O is 1.23 V, an electrolysis reaction occurs when a voltage higher than that is applied. In the electrolysis for adjusting the reducing atmosphere as in this case, the oxygen partial pressure is sufficiently lowered if only a slight amount of H ₂ (about 1%) is present.

  Step S7: It is determined whether or not the oxygen partial pressure is equal to or less than a predetermined value. If the oxygen partial pressure is equal to or less than the predetermined value, the process proceeds to step S8 to lower the temperature of the fuel cell B, and the oxygen partial pressure If is not less than the predetermined value, the process returns to step S6.

  Next, a fuel cell system according to a second embodiment will be described with reference to FIGS. FIG. 4 is a block diagram showing the overall configuration of the fuel cell system according to the second embodiment of the present invention, and FIG. 5 is a block diagram showing the function of the controller unit. In addition, about the thing equivalent to what was demonstrated in embodiment mentioned above, the code | symbol same as them is attached | subjected and detailed description is abbreviate | omitted.

  The fuel cell system A2 according to the second embodiment includes a fuel cell B, a controller unit C, an oxygen partial pressure meter P, a voltmeter 60 as a gas concentration detection unit, a power storage unit 20, and flow rate adjustment units 30I and 30O. , 31I, 31O are the main hardware configurations.

In this embodiment, the point which employ | adopts the voltmeter 60 which detects the output voltage of a fuel cell as a gas concentration detection part is different from fuel cell system A1 mentioned above.
The voltmeter 60 measures the gas concentration as an output voltage. That is, when the fuel cell B is generating power in the constant current operation mode, the decrease in gas concentration is proportional to the decrease in output voltage. Therefore, an attempt is made to detect the gas concentration by measuring the output voltage.

The controller unit C includes a controller 50 including a CPU (Central Processing Unit), an interface circuit, and the like, and a storage unit 51 including a hard disk as an information recording medium.
Then, by executing the program used for the fuel cell system stored in the storage unit 51, the above-mentioned first supply stop means 50A, gas concentration determination means 50B, second supply stop means 50C, oxygen content In addition to the pressure determination means 50E, the power supply start means 50F, the power supply stop means G, and the power supply stop means 50G, the functions of the constant current operation means 50H described below are exhibited.

The constant current operation means 50H performs the constant current operation of the fuel cell B after stopping the hydrocarbon gas.
“After stopping the hydrocarbon gas” is after stopping the air supply via the flow rate adjusting unit 31I. Further, when the gas concentration determination means 50B determines that the concentration of the hydrocarbon gas has decreased to a predetermined value or less, the air supply is stopped via the second flow rate adjustment unit 31I. It may be the same as described above.

  The operation of the fuel cell system A2 having the above configuration will be described with reference to FIG. FIG. 6 is a flowchart showing an operation stop mode of the fuel cell system according to the second embodiment.

When the operation of the fuel cell is stopped, the process proceeds to step S1.
Step S1 (simply abbreviated as “S1” in the figure. The same applies hereinafter): Only the flow rate of the hydrocarbon gas is stopped via the first flow rate adjusting unit 301, and the process proceeds to Step S2. At this time, air is kept flowing.
Step S2: The power generation is continued in the constant current operation mode in which the output current is constant, and the process proceeds to Step S3. At this time, the generated power is stored in the power storage unit 20.

Step S3: Check the output voltage and proceed to Step S4.
Step S4: It is determined whether or not the output voltage has decreased below a predetermined value. If the output voltage has decreased below the predetermined value, the process proceeds to Step S5. Otherwise, the process returns to Step S2.

Step S5: Stop the air supply via the second flow rate adjusting unit 31I and proceed to Step S6.
Step S6: Electrolysis is performed with the current direction reversed, and the process proceeds to step S7. By electrolyzing H ₂ O contained in the hydrocarbon gas, oxidation of the fuel electrode (Ni) by H ₂ O is prevented, and a decrease in the reaction activity of the fuel electrode is prevented.

  Step S7: It is determined whether or not the oxygen partial pressure is equal to or lower than a predetermined value. If the oxygen partial pressure is equal to or lower than the predetermined value, the process proceeds to step S8 to lower the temperature of the fuel cell. If not less than the predetermined value, the process returns to step S6.

  Next, a fuel cell system according to a third embodiment will be described with reference to FIGS. FIG. 7 is a block diagram showing the overall configuration of the fuel cell system according to the third embodiment of the present invention, and FIG. 8 is a block diagram showing the function of the controller unit. In addition, about the thing equivalent to what was demonstrated in embodiment mentioned above, the code | symbol same as them is attached | subjected and detailed description is abbreviate | omitted.

  As shown in FIG. 7, a fuel cell system A3 according to a third embodiment of the present invention includes a fuel cell B, a controller unit C, an oxygen partial pressure gauge P, an ammeter 10 as a gas concentration detection sensor, and a power storage. The unit 20, the flow rate adjusting units 30I, 30O, 31I, 31O, the pressure gauge 65 as the pressure measuring unit, the pressure adjusting mechanism 70, and the gas circulation pump 75 are the main hardware configurations.

  The pressure gauge 65 is for measuring the pressure of hydrocarbon gas. Specifically, it is disposed in the outflow passage 13 of hydrocarbon gas and measures the pressure in the outflow passage 13, and the measured value is transmitted to the controller unit C.

The pressure adjusting mechanism 70 shown in the present embodiment is for adjusting the pressure of hydrocarbon gas, and includes a pneumatic cylinder 71 and a cylinder driving unit 72 for driving the pneumatic cylinder 71.
The cylinder driving unit 72 adjusts the pressure of the hydrocarbon gas by increasing / decreasing a telescopic rod (not shown) of the pneumatic cylinder 71 by a driving signal transmitted from the controller unit C.
That is, the pressure in the inflow passage 11 fluctuates by the power generation by the remaining hydrocarbon gas or the control of the reducing atmosphere by the electrolysis of H ₂ O. Therefore, the pressure in the inflow passage 11 is adjusted so as to offset this fluctuation. They keep it constant.

The gas circulation pump 75 is disposed in the circulation path 15 connected between the inflow path 11 and the outflow path 13, and circulates hydrocarbon gas in the path of the inflow path 11, the fuel cell B and the outflow path 13. In this way, it is driven by a drive signal transmitted from the controller unit C.
That is, when the supply of the hydrocarbon gas is stopped, the gas flow in the inflow path 11 and in the electrode is deteriorated. In order to improve this, the gas circulation pump 75 circulates the hydrocarbon gas smoothly to improve the fuel utilization rate, thereby improving the effect of preventing carbon deposition and electrode oxidation.

As shown in FIG. 8, the controller unit C has a controller 50 including a CPU (Central Processing Unit), an interface circuit, and the like, and a storage unit 51 including a hard disk as an information recording medium.
Then, by executing the program used for the fuel cell system stored in the storage unit 51, the above-mentioned first supply stop means 50A, gas concentration determination means 50B, second supply stop means 50C, constant voltage In addition to the operation means 50D, the power supply start means 50E, the oxygen partial pressure determination means 50F, and the power supply stop means 50G, the functions of the pressure adjustment means 50I and the pump operation means 50J are exhibited.

(8) A function of adjusting the pressure to be a predetermined value via the pressure adjusting mechanism 70 based on the pressure measured by the pressure measuring unit 65. This is referred to as “pressure adjusting means 50I”.
That is, the pressure in the outflow / inflow path is fluctuated up and down by power generation with residual hydrocarbon gas or control of the reducing atmosphere by electrolysis of H ₂ O, so that this is kept constant.

(9) A function of operating the gas circulation pump 75 by stopping the hydrocarbon gas. This is referred to as “pump operating means 50j”.
That is, when the supply of the hydrocarbon gas is stopped, the gas flow in the outflow / inlet channel and the electrode deteriorates, so the gas circulation pump 75 improves the gas flow, thereby improving the fuel utilization rate, It can contribute to the effect of preventing carbon deposition and electrode oxidation.

The operation of the fuel cell system A3 having the above configuration will be described with reference to FIG. FIG. 9 is a flowchart showing the operation stop mode of the fuel cell system A3.
When the operation of the fuel cell is stopped, the process proceeds to step S1.

Step S1: Only the hydrocarbon gas is stopped via the first flow rate adjusting unit 30I, and the process proceeds to Step 2. At this time, air is kept flowing.
Step S2: The gas circulation pump 75 is operated, and the process proceeds to Step S3.
Step S3: The power generation is continued in the constant voltage operation mode in which the output voltage is constant, and the process proceeds to Step S4. At this time, the generated power is stored in the power storage unit 20.

Step S4: Check the output current and proceed to Step S5.
Step S5: It is determined whether or not the output current has decreased below a predetermined value. If the output current has decreased below the output current, the process proceeds to step S6, and if not, the process returns to step S3.

Step S6: Stop the air supply via the second flow rate adjusting unit 31l and proceed to Step S7.
Step S7: Reverse the current direction to supply electric power to perform electrolysis, and proceed to Step S8. By electrolyzing H ₂ O (moisture) contained in the hydrocarbon gas, oxidation of the fuel electrode (Ni) by H ₂ O is prevented, and a decrease in reaction activity of the fuel electrode is prevented.

  Step S8: It is determined whether or not the oxygen partial pressure is not more than a predetermined value. If the oxygen partial pressure is not more than the predetermined value, the process proceeds to step S9 to stop the gas circulation pump 75 and lower the temperature of the fuel cell. If the oxygen partial pressure is not less than the predetermined value, the process returns to step S7.

  Next, a fuel cell system A4 according to a fourth embodiment will be described with reference to FIGS. FIG. 10 is a block diagram showing the overall configuration of the fuel cell system according to the first embodiment of the present invention, and FIG. 11 is a block diagram showing the function of the controller unit. In addition, about the thing equivalent to what was demonstrated in embodiment mentioned above, the code | symbol same as them is attached | subjected and detailed description is abbreviate | omitted.

  A fuel cell system A4 according to the fourth embodiment of the present invention includes a fuel cell B, a controller unit C, an oxygen partial pressure meter P, an ammeter 10 as a gas concentration detection unit, a power storage unit 20, and a flow rate adjustment unit 30I. , 30O, 31I, 31O, the temperature adjustment mechanism 80, and the temperature measurement unit 85 are the main components.

The temperature adjustment mechanism 80 is, for example, a heater or a burner for adjusting the temperature of the fuel cell B, and is formed so as to cover the outer surface of the fuel cell B in this embodiment.
The temperature measuring unit 85 is for measuring the temperature of the fuel cell B, and the measured temperature data is output to the controller unit C.

  The controller unit C includes a controller 50 including a CPU (Central Processing Unit), an interface circuit, and the like, and a storage unit 51 including a hard disk as an information recording medium.

  Then, by executing the program used for the fuel cell system stored in the storage unit 51, the above-mentioned first supply stop means 50A, gas concentration determination means 50B, second supply stop means 50C, constant voltage In addition to the operation means 50D, the power supply start means 50E, the oxygen partial pressure determination means 50F, and the power supply stop means 50G, the following functions are exhibited.

(10) A function for determining whether or not the temperature of the fuel cell B measured by the temperature measuring unit has become equal to or lower than a predetermined value, and this is referred to as “temperature determination means 50K”.
The “predetermined value” is a temperature at which the power generation efficiency does not deteriorate when power generation using the remaining hydrocarbon gas is continued.

(11) A function of starting heating of the fuel cell B by the temperature adjustment mechanism 80 when the temperature determination unit 50K determines that the fuel cell B has become a predetermined temperature or less. This is referred to as “heating start means 50L”.
That is, if the temperature of the fuel cell B is extremely lowered while continuing the power generation using the remaining hydrocarbon gas, the power generation efficiency deteriorates. Therefore, the fuel cell B is prevented from falling below a predetermined temperature.

  The operation of the fuel cell system A4 having the above configuration will be described with reference to FIG. FIG. 12 is a flowchart showing the operation stop mode of the fuel cell system A4.

When the operation of the fuel cell is stopped, the process proceeds to step S1.
Step S1 (simply abbreviated as “S1” in the figure. The same applies hereinafter): Only the hydrocarbon gas is stopped via the first flow rate adjusting unit 30I, and the process proceeds to Step S2. At this time, air is kept flowing.
Step S2: The power generation is continued in the constant voltage operation mode in which the output voltage is constant, and the process proceeds to Step S3. At this time, the generated power is stored in the power storage unit 20.

Step S3: Check the temperature of the fuel cell B, and proceed to Step S4.
Step S4: It is determined whether or not the temperature of the fuel cell B is equal to or lower than a predetermined value. If the temperature is equal to or lower than the predetermined value, the process proceeds to Step S5. If the temperature is not less than the predetermined value, the process returns to step S3.
Step S5: The heating of the fuel cell B by the temperature adjustment mechanism 70 is started, and the process proceeds to Step S6.
Step S6: Check the output current and proceed to Step S7.
Step S7: It is determined whether or not the output current has decreased below a predetermined value. If the output current has decreased below the output current, the process proceeds to step S8, and if not, the process returns to step S2.

Step S8: The air supply is stopped via the second flow rate adjusting unit 31I, and the process proceeds to Step S9.
Step S9: Electrolysis is performed with the current direction reversed, and the process proceeds to step S10. By electrolyzing H ₂ O contained in the fuel gas, oxidation of the fuel electrode (Ni) by H ₂ O is prevented, and a decrease in the reaction activity of the fuel electrode is prevented.

  Step S10: It is determined whether or not the oxygen partial pressure is less than or equal to a predetermined value. If the oxygen partial pressure is less than or equal to the predetermined value, the process proceeds to step S11 to lower the temperature of the fuel cell B, and the oxygen partial pressure If is not less than the predetermined value, the process returns to step S9.

The present invention is not limited to the above-described embodiments, and the following modifications can be made.
In the above-described embodiment, the example in which the oxygen partial pressure gauge P is disposed in the inflow path 11 has been described. However, the oxygen partial pressure gauge P may be disposed in the outflow path 13, or both the inflow path 11 and the outflow path 13. You may arrange in.

In each of the above-described embodiments, the ammeter and the voltmeter have been described as examples of the gas concentration detection unit. However, the sensor for directly detecting the gas concentration is used for the inflow of the hydrocarbon gas into the fuel cell. You may arrange | position in a path or an outflow path, and may arrange | position in both an inflow path and an outflow path.

In each of the above-described embodiments, an example in which each function described by a single controller unit has been described has been described. However, distributed processing is performed by a plurality of controller units and thus by a plurality of computers that control the fuel cell. You may do it.

1 is a block diagram showing an overall configuration of a fuel cell system according to a first embodiment of the present invention. It is a block diagram which shows the function of a controller unit. It is a flowchart which shows the operation stop mode of a fuel cell system same as the above. It is a block diagram which shows the whole structure of the fuel cell system which concerns on 2nd embodiment of this invention. It is a flowchart which shows the operation stop mode of a fuel cell system same as the above. It is a flowchart which shows the operation stop mode of the fuel cell system which concerns on 2nd embodiment. It is a block which shows the whole structure of the fuel cell system which concerns on 3rd embodiment of this invention. It is a block diagram which shows the function of a controller unit. It is a flowchart which shows the operation stop mode of a fuel cell system same as the above. It is a block diagram which shows the whole structure of the fuel cell system which concerns on 4th embodiment of this invention. It is a block diagram which shows the function of a controller unit. It is a flowchart which shows the operation stop mode of a fuel cell system same as the above.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10,60 Gas concentration detection part 11 Inflow path 13 Outflow path 20 Power storage part 30I First flow rate adjustment part 31I Second flow rate adjustment part 40 Solid electrolyte type cell 41 Fuel electrode 42 Air electrode 50A First feed stop means 50B Gas concentration determination means 50C Second supply stop means 50D Constant voltage operation means 50E Power supply start means 50F Oxygen partial pressure determination means 50G Power supply stop means 50H Constant current operation means 50I Pressure adjustment means 50J Pump operation means 50K Temperature determination means 50L Heating Starting means 51 Information recording medium 65 Pressure measuring unit 70 Pressure adjusting mechanism 75 Gas circulation pump 80 Temperature adjusting mechanism 85 Temperature measuring unit B Fuel cell P Oxygen partial pressure measuring unit

Claims (15)

A fuel cell that generates power by flowing a hydrocarbon gas and air into and out of a fuel electrode and an air electrode of a solid oxide cell, and a first flow rate adjustment for adjusting the flow rate of the hydrocarbon gas , A second flow rate adjusting unit for adjusting the flow rate of the air, a gas concentration detecting unit for detecting the concentration of the hydrocarbon gas, and an oxygen partial pressure measuring unit for measuring the oxygen partial pressure of the hydrocarbon gas A fuel cell system provided with
A first feed stop means for stopping only the feed of the hydrocarbon gas via the first flow rate adjustment unit;
Gas concentration determination means for determining whether or not the concentration of the hydrocarbon gas detected by the gas concentration detection unit has decreased to a predetermined value or less;
When it is determined by the gas concentration determination means that the concentration of the hydrocarbon gas has decreased to a predetermined value or less, the second supply stop means for stopping the supply of air via the second flow rate adjustment unit;
After the air supply is stopped, power supply starting means for starting supply of electric power having the opposite polarity to the fuel electrode and the air electrode,
Oxygen partial pressure determining means for determining whether or not the oxygen partial pressure measured by the oxygen partial pressure measuring unit has become a predetermined value or less;
When the oxygen partial pressure determining means determines that the oxygen partial pressure has become a predetermined value or less, it has a power supply stopping means for stopping the electric power of the reverse polarity supplied to the fuel electrode and the air electrode. Fuel cell system. The fuel cell system according to claim 1, wherein the gas concentration detection unit is an ammeter that detects an output current of the fuel cell as a concentration of the hydrocarbon gas . 2. The fuel cell system according to claim 1, wherein the gas concentration detection unit is a voltmeter that detects the output voltage of the fuel cell as the concentration of the hydrocarbon gas . The fuel cell system according to claim 1, wherein the gas concentration detection unit is disposed in an inflow path for allowing hydrocarbon gas to flow into the fuel cell. The fuel cell system according to claim 1, wherein the gas concentration detection unit is disposed in a hydrocarbon gas outflow passage . The fuel cell system according to any one of claims 1 to 5, further comprising constant voltage operation means for performing constant voltage operation of the fuel cell after stopping the supply of hydrocarbon gas . The fuel cell system according to any one of claims 1 to 5, further comprising a constant current operation means for performing a constant current operation of the fuel cell after stopping the supply of hydrocarbon gas . The gas concentration determining means, when the concentration of the hydrocarbon gas is determined to have decreased below a predetermined value, any one of claims 1 to 7, characterized in that to start the supply of electric power by the power supply start means The fuel cell system described in 1. A power storage unit for storing surplus power generated by the fuel cell is provided, and the power storage unit is used as a power supply source having a reverse polarity supplied to the fuel electrode and the air electrode. The fuel cell system according to any one of 1 to 8. The fuel cell system according to claim 9, wherein the power storage unit is a secondary battery or a capacitor . While providing a pressure measuring unit for measuring the pressure of the hydrocarbon gas and a pressure adjusting mechanism for adjusting the pressure of the hydrocarbon gas,
Based on the pressure measured by the pressure measuring unit, via a pressure adjusting mechanism, any one of claim 1 to 10, its pressure is characterized in that a pressure adjusting means for adjusting to a predetermined value The fuel cell system described in 1. A temperature measuring unit for measuring the temperature of the fuel cell and a temperature adjusting mechanism for adjusting the temperature of the fuel cell are provided.
Temperature determination means for determining whether or not the temperature of the fuel cell measured by the temperature measurement unit has become a predetermined value or less;
The heating start means for starting heating of the fuel cell by the temperature adjusting mechanism is provided when the temperature determination means determines that the temperature of the fuel cell has become equal to or lower than a predetermined value . The fuel cell system according to any one of claims. A gas circulation pump for circulating the hydrocarbon gas is disposed between the inflow path for flowing the hydrocarbon gas into the fuel cell and the outflow path for flowing out from the fuel cell,
The fuel cell system according to any one of claims 1 to 12, further comprising pump operating means for operating a gas circulation pump after stopping the supply of hydrocarbon gas . A fuel cell that generates power by flowing a hydrocarbon gas and air into and out of a fuel electrode and an air electrode of a solid oxide cell, and a first flow rate adjustment for adjusting the flow rate of the hydrocarbon gas , A second flow rate adjusting unit for adjusting the flow rate of the air, a gas concentration detecting unit for detecting the concentration of the hydrocarbon gas, and an oxygen partial pressure measuring unit for measuring the oxygen partial pressure of the hydrocarbon gas A program used for a fuel cell system provided with
A function of stopping only the supply of hydrocarbon gas via the first flow rate adjustment unit;
A function of determining whether or not the concentration of hydrocarbon gas detected by the gas concentration detector has decreased to a predetermined value or less;
When it is determined by the gas concentration determination means that the concentration of the hydrocarbon gas has decreased to a predetermined value or less, a function of stopping air supply via the second flow rate adjustment unit;
After the air supply is stopped, the function of starting the supply of electric power of the opposite polarity to the fuel electrode and the air electrode,
A function of determining whether or not the oxygen partial pressure measured by the oxygen partial pressure measuring unit has become a predetermined value or less;
When it is determined that the oxygen partial pressure has become a predetermined value or less, the computer that controls the fuel cell system has a function of stopping the reverse polarity power supplied to the fuel electrode and the air electrode. A program used for a fuel cell system . An information recording medium on which a program used for the fuel cell system according to claim 14 is recorded .

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