JP2011210567A - Solid oxide fuel battery power generation apparatus, and operation stop method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid oxide fuel battery power generation apparatus capable of preventing deterioration of power generation performance of a solid oxide fuel battery even though it is again operated after an emergency stop by preventing a change of a crystal structure of an air electrode layer upon the emergency stop and miniaturizing the solid oxide fuel battery power generation apparatus, and to provide a stopping method thereof.SOLUTION: In the solid oxide fuel battery power generation apparatus, following steps toward stopping of the air supply to an air electrode are carried out for preventing the change of the crystal structure of the air electrode layer when an emergency stop is performed by stopping at least the supply of a fuel gas. Air is supplied to the air electrode layer by an air buffer tank 3 or an air blower 4. When a voltage of the solid oxide fuel battery 2 becomes lower than a pre-determined threshold, supply of air is once suspended by an electromagnetic valve 6 or an electromagnetic switch 7. When the voltage of the solid oxide fuel battery 2 becomes higher than the threshold due to voltage rise for the second time, supply of air is carried out. This cycle including the above steps is repeated. When the voltage finally never becomes higher than the threshold, supply of air is stopped.

Description

  The present invention relates to a solid oxide fuel cell power generation apparatus including a solid oxide fuel cell that generates power by supplying fuel gas to a fuel electrode layer and supplying oxidant gas to an oxidant electrode layer, and a method for shutting down the same. Is.

  As a conventional solid oxide fuel cell power generator, a solid oxide fuel cell, a fuel gas supply line for supplying fuel gas to the solid oxide fuel cell, and air (oxidant) in the solid oxide fuel cell Oxidant gas supply means for supplying gas), an oxidant gas supply line for guiding the air supplied from the oxidant gas supply means to the air electrode layer (oxidant electrode layer), and the solid oxide fuel There is known a power supply line that leads power from a battery to an external load and an inverter that is interposed in the power supply line and converts DC power into AC power.

  This solid oxide fuel cell is configured by laminating a plurality of power generation cells and separators each having a fuel electrode layer disposed on one surface of a solid electrolyte and an oxidant electrode layer disposed on the other surface, A fuel gas is supplied to the fuel electrode layer through the fuel gas supply line, and an oxidant gas is supplied to the oxidant electrode layer through the oxidant gas supply line, thereby generating a power generation reaction. And electric power is supplied to an external load through the electric power supply line provided with the inverter from the separator located in the both ends of the laminated body formed by laminating a plurality of power generation cells and separators.

  Here, the solid electrolyte layer is made of a lanthanum gallate material (LSMCC) to which strontium, magnesium, and cobalt are added.

  The fuel electrode layer is composed of Ni cermet or the like, and the air electrode layer is composed of samarium strontium cobaltite (SSC) or the like.

  On the other hand, an air blower, an air buffer tank, or the like is generally used as the oxidant gas supply means.

  When such a solid oxide fuel cell power generator is used for a long period of time, there is a possibility that a serious failure described in Table 1 below occurs. Table 1 below also shows the state of the fuel gas supply line and the oxidant gas supply line when a serious failure occurs.

  When these major faults A to E occur, the solid oxide fuel cell power generator immediately stops immediately, the load current is stopped, and the supply of fuel gas and air is also stopped.

  Here, in order to prevent the oxidation of the fuel electrode layer and the change of the crystal structure of the air electrode layer in the state where the load current is stopped after the emergency stop due to the major faults A to E, the inventor again The fuel gas was supplied to the one capable of supplying fuel gas to the electrode layer, and the temperature of the solid oxide fuel cell was lowered while supplying air to the one capable of supplying air to the air electrode layer. And the state of the fuel electrode layer side and the air electrode layer side of each power generation cell was confirmed.

  In the serious failure A, the inverter has an abnormality, but neither the fuel gas supply line nor the oxidant gas supply line has an abnormality. Therefore, after the emergency stop, the fuel gas is supplied to the fuel gas supply line and the oxidant gas supply line. The temperature of the solid oxide fuel cell was lowered while supplying air. As a result, as shown in FIG. 3 (a), it was confirmed that the fuel electrode layer of the power generation cell was not oxidized, and as shown in FIG. 3 (b), the air electrode layer was not discolored. It was confirmed that the crystal structure was not changed.

  In the major fault B to the major fault E, an abnormality occurs in the fuel gas supply line, and the fuel gas cannot be supplied to the fuel gas supply line. Therefore, the solid oxide type is not supplied to the fuel gas supply line. The temperature of the fuel cell was lowered. Then, since there was no fuel gas in the fuel electrode layer, it was thought that the fuel electrode layer was oxidized by the surrounding air and turned black, but FIG. 4 (a), FIG. 5 (a), FIG. 6 (a) and As shown in FIG. 7A, it was confirmed that the fuel electrode layer was hardly oxidized. This is presumed that the fuel electrode layer was held in the reducing atmosphere by the remaining fuel gas because the fuel gas remained around the solid oxide fuel cell and in the fuel gas supply line.

  In the major fault B to the major fault E, the major fault B and the major fault C have no abnormality in the oxidant gas supply line, so that the solid oxide form is supplied while supplying air to the air electrode layer even after an emergency stop. The temperature of the fuel cell was lowered. As a result, as shown in FIGS. 4B and 5B, it was confirmed that the air electrode layer was not discolored and the crystal structure was not changed by XRD analysis.

  Further, in the serious failure D and the serious failure E, the air blower fails and air cannot be supplied to the oxidant gas supply line. Therefore, the solid oxide fuel cell is not supplied without supplying air to the oxidant gas supply line. The temperature was lowered. Then, as shown in FIGS. 6B and 7B, it was confirmed that the air electrode layer turned black and the crystal structure was changed by XRD analysis. This is because, as described above, the remaining fuel gas flows into the fuel electrode layer, but the air blower has failed, and sufficient air cannot be supplied to the air electrode layer. It is presumed that the oxygen ions of the air electrode layer itself moved to the fuel electrode layer and the crystal structure of the air electrode layer changed irreversibly.

Next, the present inventor placed separators on both ends of the power failure cells of the major fault C in which the crystal structure of the air electrode layer has not changed, the major fault D in which the crystal structure of the air electrode layer has changed, and the major fault E. The cell voltage before and after the emergency stop of the single cell was measured. Here, “before emergency stop” means immediately before the emergency stop, and “after emergency stop” means when the power generator is restarted after the emergency stop. The operating conditions at that time were set to a fuel utilization rate of 80%, and the amount of fuel gas (hydrogen gas) per unit area supplied per minute was set to 5.6 cc / cm ² · min.

  Then, the cell voltage of the serious failure C was 0.703 V before and after the emergency stop, and it was confirmed that the cell voltage did not change.

  It was confirmed that the cell voltage of the serious failure D was 0.722V before the emergency stop, but 0.708V after the emergency stop, which was decreased by 0.014V.

  Furthermore, it was confirmed that the cell voltage of the serious failure E was 0.732V before the emergency stop, but became 0.688V after the emergency stop, and also decreased by 0.044V.

  As a result, it was confirmed that the cell voltage of the power generation cell was lowered by changing the crystal structure of the air electrode layer.

  Therefore, the present inventor measured the composition of the air electrode layer of the major fault C in which the cell voltage of the power generation cell hardly changed and the major fault E in which the cell voltage of the power generation cell was greatly reduced.

  Table 2 below shows the composition of the air electrode layer of the major fault C, and Table 3 below shows the composition of the air electrode of the major fault E.

  When both are compared, the oxygen component in the A part (center part) does not change, but the oxygen component in the B part and the C part is more in the air electrode layer in the serious fault E than in the air electrode layer in the serious fault C. It was confirmed that the oxygen component was reduced by 2 to 3 at%.

  From these results and the XRD evaluation results, when the oxygen component of the air electrode layer is reduced, the crystal structure of the air electrode layer is changed, and the ionic conductivity is reduced. It was confirmed that the power generation performance of the solid oxide fuel cell deteriorates.

  Therefore, in the following Patent Document 1, the present inventor, when the supply of fuel gas to at least the fuel electrode layer stops and makes an emergency stop, the air in the air blower or the air buffer tank is transferred to the air electrode layer by the residual fuel gas. The solid oxide fuel cell prevents the change in the crystal structure of the air electrode layer by continuing to supply until it disappears, and the power generation performance of the solid oxide fuel cell does not deteriorate even if it is restarted after an emergency stop A method for shutting down the generator is proposed.

  Furthermore, by providing a storage battery that stores part of the power obtained by the power generation reaction of the solid oxide fuel cell power generator, the air blower can be operated even in the event of an emergency stop due to a complete power failure. A solid oxide fuel cell power generator that can be made is proposed.

  Further, when the supply of fuel gas to the fuel electrode layer is stopped and an emergency stop is performed, even if the air blower fails and does not move, the air in the air buffer tank is supplied to the air electrode layer and the remaining fuel is supplied to the fuel electrode layer. By supplying gas until it runs out of gas, the crystal structure of the air electrode layer is prevented from changing, and the power generation performance of the solid oxide fuel cell does not deteriorate even if it is restarted after an emergency stop. A fuel cell power generation apparatus and a method for stopping operation thereof are proposed.

JP 2009-87862 A

  However, the solid oxide fuel cell power generator and the operation method thereof described in Patent Document 1 need to enlarge the air buffer tank in order to continue supplying air to the air electrode layer until the remaining fuel gas is exhausted. There was also a need to install a large capacity storage battery. For this reason, there is a problem that the solid oxide fuel cell power generator is increased in size as a whole.

  The present invention has been made in view of such circumstances, and by preventing a change in the crystal structure of the air electrode layer during an emergency stop, the power generation of the solid oxide fuel cell can be performed even after restarting after an emergency stop. It is an object of the present invention to provide a solid oxide fuel cell power generator and a method for shutting down the solid oxide fuel cell power generator capable of reducing performance and reducing the size of the solid oxide fuel cell power generator.

  In order to solve the above problems, the solid oxide fuel cell power generator according to claim 1 is configured such that a fuel gas is supplied to the fuel electrode layer and an oxidant gas is supplied to the oxidant electrode layer. A solid oxide fuel cell that generates a power generation reaction, a fuel gas supply line that supplies fuel gas to the fuel electrode layer, and an oxidant gas supply unit that supplies an oxidant gas are provided. An oxidant gas supply line for supplying the obtained oxidant gas to the oxidant electrode layer, and the oxidant gas supply means includes at least a fuel gas supply stop and an emergency stop. An oxidant gas supply control means for controlling whether or not to supply the oxidant gas to the oxidant electrode layer based on a voltage threshold value of the solid oxide fuel cell is provided. It is.

  Further, a solid oxide fuel cell power generator according to claim 2 is the solid oxide fuel cell power generator according to claim 1, wherein the oxidant gas supply control means and the oxidant gas supply means include A storage battery for storing part of the electric power obtained by the power generation reaction of the solid oxide fuel cell is provided.

  The solid oxide fuel cell power generator according to claim 3 is the solid oxide fuel cell power generator according to claim 2 or 3, wherein the oxidant gas supply means controls the air pressure. It is an oxidant gas supply unit in which an oxidant gas blower or a compressor is provided in a front stage portion of an oxidant gas buffer tank that is stabilized and supplied to a solid oxide fuel cell.

  According to a fourth aspect of the present invention, there is provided a method for stopping the operation of the solid oxide fuel cell power generator, wherein at least when the supply of the fuel gas is stopped and an emergency stop is performed, the oxidant gas supply unit supplies the oxidant electrode layer to the oxidant electrode layer. When the voltage of the solid oxide fuel cell becomes lower than a predetermined threshold by the oxidant gas supply control means, the supply of the oxidant gas is stopped once and again. When the voltage rises and becomes higher than the threshold value, the process of supplying the oxidant gas is repeated. When the voltage does not eventually become higher than the threshold value, the oxidant gas is supplied. The supply is stopped.

  According to the first aspect of the present invention, when the supply of the fuel gas is stopped and the emergency stop is performed at least in the oxidant gas supply means, the oxidation gas is supplied based on the voltage threshold value of the solid oxide fuel cell. Since the oxidant gas supply control means for controlling whether or not to supply the oxidant gas is provided, the supply amount of the oxidant gas supplied to the oxidant electrode layer is adjusted by the oxidant gas supply control means. It becomes possible.

  According to a second aspect of the present invention, the oxidant gas supply control means and the oxidant gas supply means store part of the electric power obtained by the power generation reaction of the solid oxide fuel cell. Since the storage battery is provided, the oxidant gas supply control means and the oxidant gas supply means can be operated even when the supply of fuel gas is stopped due to a complete power failure and the emergency stop occurs. .

  Further, according to the invention described in claim 3, the oxidant gas supply means stabilizes the pressure of the oxidant gas and supplies the solid oxide fuel cell to the front stage of the oxidant gas buffer tank. Since the oxidant gas blower or compressor is provided with the oxidant gas blower or compressor, the above oxidant gas blower or compressor cannot be operated due to a failure when the fuel gas supply is stopped and the emergency stop is performed. It is possible to supply the oxidant gas of the gas buffer tank to the oxidant electrode layer.

  According to the invention described in claim 4, since the oxidant gas is supplied to the oxidant electrode layer by the oxidant gas supply unit, the remaining fuel gas flows into the fuel electrode layer. Even if the oxygen ions of the oxidant gas move to the fuel electrode layer, the oxygen ions of the oxidant gas continue to be supplied to the oxidant electrode layer. It becomes possible to prevent. As a result, it is possible to prevent the power generation performance of the solid oxide fuel cell from being deteriorated even if it is restarted after an emergency stop.

  Further, when the voltage of the solid oxide fuel cell becomes lower than a predetermined threshold by the oxidant gas supply control means, the supply of the oxidant gas is once stopped and the voltage is increased again. When the voltage becomes higher than the threshold value, the process of supplying the oxidant gas is repeated. When the voltage does not eventually become higher than the threshold value, the supply of the oxidant gas is stopped. Therefore, the supply amount of the oxidant gas can be minimized, and the oxidant gas buffer tank of the oxidant gas supply unit can be downsized.

  In addition, since the time for supplying the oxidant gas (cumulative) is also reduced, it is possible to reduce the power required to operate the oxidant gas blower in the event of a complete power outage, and the storage battery has a smaller capacity than before. Can be installed.

  As a result, the solid oxide fuel cell power generator can be reduced in size.

1 is a schematic configuration diagram showing an embodiment of a solid oxide fuel cell power generator according to the present invention. It is sectional drawing which shows the single cell of the solid oxide fuel cell of FIG. 1 shows a power generation cell of a conventional solid oxide fuel cell that has been urgently stopped due to a serious failure, in which (a) is a plan view showing a fuel electrode layer side, and (b) is a plan view showing an air electrode layer side. is there. The power generation cell of the conventional solid oxide fuel cell which stopped urgently by another serious failure is shown, (a) is a top view which shows the fuel electrode layer side, (b) is the plane which shows the air electrode layer side FIG. The power generation cell of the conventional solid oxide fuel cell which stopped urgently by another serious failure is shown, (a) is a top view which shows the fuel electrode layer side, (b) is the plane which shows the air electrode layer side FIG. The power generation cell of the conventional solid oxide fuel cell which stopped urgently by another serious failure is shown, (a) is a top view which shows the fuel electrode layer side, (b) is the plane which shows the air electrode layer side FIG. The power generation cell of the conventional solid oxide fuel cell which stopped urgently by another serious failure is shown, (a) is a top view which shows the fuel electrode layer side, (b) is the plane which shows the air electrode layer side FIG.

Hereinafter, an embodiment of a solid oxide fuel cell power generator according to the present invention will be described with reference to FIGS.
As shown in FIG. 1, the solid oxide fuel cell power generator according to the present invention includes a solid oxide fuel cell 2 housed inside a can body 1 and an air buffer tank (outside the can body 1). An oxidant gas supply unit 5 provided with an air blower (oxidant gas blower) 4 at the front stage of the oxidant gas buffer tank) 3, a solenoid valve (oxidant gas supply control means) 6, an electromagnetic switch (oxidant gas supply control) Means) 7, a converter 8, a storage battery 9, and a system power supply 10.

  As shown in FIG. 2, this solid oxide fuel cell 2 has a power generation in which a fuel electrode layer 12 is disposed on one surface of a solid electrolyte layer 11 and an air electrode layer (oxidant electrode layer) 13 is disposed on the other surface. A single cell 18 is configured by disposing a fuel electrode current collector 15 and an air electrode current collector 16 on the outside of the cell 14, and disposing a separator 17 on the outside of the current collectors 15, 16. As shown in FIG. 1, a plurality of single cells 18 are stacked and the stacked body is sandwiched between flanges 19a and 19b.

  Here, the solid electrolyte layer 11 is composed of a lanthanum gallate material (LSGMC) to which strontium, magnesium, and cobalt are added.

  The fuel electrode layer 12 is made of Ni cermet, and the air electrode layer 13 is made of samarium strontium cobaltite (SSC).

  Further, the fuel electrode current collector 15 and the air electrode current collector 16 are formed of a porous sintered plate.

  The separator 17 is made of a stainless steel plate, and has a fuel gas passage 19 for supplying fuel gas to the fuel electrode layer 12 and an oxidant gas passage 20 for supplying air (oxidant gas) to the air electrode layer 13. It is installed. Further, the separator 17 is provided with fuel gas holes (not shown) and oxidant gas holes (not shown) at positions away from the power generation cell 14. The fuel gas manifold (not shown) and the oxidant gas manifold (not shown) are communicated between the agent gas holes through a manifold ring (not shown) made of an insulating ceramic. Is formed.

  A fuel gas passage (not shown) for supplying fuel gas to the fuel gas manifold is formed in the flange 19a disposed on the lowermost side of the solid oxide fuel cell 2. A fuel gas supply line 21 for introducing the fuel gas into the fuel gas passage is connected to the opening of the fuel gas passage.

  Further, an oxidant gas flow path (not shown) for supplying an oxidant gas to the oxidant gas manifold is formed in the flange 19b disposed on the uppermost side of the solid oxide fuel cell 2. . The oxidant gas flow path is provided with one end of an oxidant gas supply line 22a for introducing air into the oxidant gas flow path.

  On the other hand, the air blower 4 takes in air from the suction port and supplies air to the air buffer tank 3 from the discharge port. The oxidant gas supply line 22b for supplying air to the air buffer tank 3 to the discharge port. One end of the pipe is piped.

  The air buffer tank 3 stabilizes the pressure of the air supplied from the air blower 4 and supplies it to the oxidant gas flow path of the flange 19b. The other end of the oxidant gas supply line 22b is provided on the inlet side. The other end of the oxidant gas supply line 22a is piped on the outlet side.

  Further, the electromagnetic valve 6 is interposed in the middle part of the oxidant gas supply line 22a, and when the voltage of the solid oxide fuel cell 2 becomes lower than a predetermined threshold, the internal valve body closes and becomes high. When it becomes, the valve body opens.

  On the other hand, the power supplied from the solid oxide fuel cell 2 to the converter 8 is supplied to the separators 17 at both ends of the laminate formed by laminating a plurality of single cells 18 of the solid oxide fuel cell 2. One end of the supply line 23a is wired.

  The converter 8 converts the power input voltage obtained by the power generation reaction of the solid oxide fuel cell 2 into an output voltage having a desired value and outputs it. The other end of the power supply line 23a is provided on the input side. Is wired. Then, the power converted into the output voltage of the desired value on the output side is output to the outside via an inverter (not shown) that converts the DC output into the AC output, and solid oxidation is performed on the output side. One end of a power supply line 23c that guides part of the power obtained from the physical fuel cell 2 to the storage battery 9 is wired.

  The storage battery 9 stores a part of the electric power obtained from the solid oxide fuel cell 2 and outputs power to the air blower 4, the electromagnetic valve 6, and the electromagnetic switch 7 when an emergency stop is performed. Thus, the other end of the power supply line 23c is wired on the input side. On the output side, a power supply line 23 d that leads power to the air blower 4, a power supply line 23 e that leads power to the electromagnetic valve 6, and a power supply line 23 f that leads power to the electromagnetic switch 7 are wired.

  Further, the electromagnetic switch 7 is interposed in the middle part of the power supply line 23d, and when the voltage of the solid oxide fuel cell 2 becomes lower than a predetermined threshold, the switch is turned OFF and the power supply line When 23d is closed and becomes high, the switch is turned on and the power supply line 23d is opened.

  Further, the system power supply 10 supplies power to the air blower 4 during normal operation, and a power supply line 23g that guides power to the air blower 4 is wired on the output side.

  According to the solid oxide fuel cell power generator configured as described above, when the supply of the air blower 4 and the fuel gas is stopped and an emergency stop is performed, the air is generated based on the threshold voltage of the solid oxide fuel cell 2. An electromagnetic switch 7 for controlling whether or not to supply air to the polar layer 13 is provided, and when the supply of fuel gas is stopped in the air buffer tank 3 and an emergency stop is performed, the solid oxide fuel cell 2 Since the electromagnetic valve 6 for controlling whether or not to supply air to the air electrode layer 13 based on the voltage threshold value is provided, the electromagnetic switch 7 and the electromagnetic valve 6 supply the air electrode layer 13 with the electromagnetic valve 7. It is possible to adjust the amount of air supplied.

  In addition, since a storage battery 9 that partially stores electric power obtained by the power generation reaction of the solid oxide fuel cell 2 is connected to the air blower 4, the electromagnetic valve 6, and the electromagnetic switch 7, the fuel is generated due to a complete power failure. Even when the gas supply is stopped and the emergency stop is performed, the air blower 4, the electromagnetic valve 6, and the electromagnetic switch 7 can be operated.

  Further, since the oxidant gas supply unit 5 provided with the air blower 4 is provided at the front stage of the air buffer tank 3 that stabilizes the air pressure and supplies the solid oxide fuel cell 2 to the fuel gas, When the air blower 4 is stopped and an emergency stop occurs, the air in the air buffer tank 3 can be supplied to the air electrode layer 13 even if the air blower 4 cannot be used due to a failure.

Next, an embodiment of a method for stopping the operation of the solid oxide fuel cell power generator configured as described above will be described.
First, the air blower 4 is operated using the system power source 10 when the fuel gas supply is stopped and the emergency stop is performed, or when the fuel gas supply is stopped due to a complete power failure and the emergency stop is performed, using the storage battery 9. Then, the air thus obtained is supplied to the air buffer tank 3, and after the air pressure is stabilized in the air buffer tank 3, the air is supplied to the air electrode layer 13.

  When the voltage of the solid oxide fuel cell 2 becomes lower than a predetermined threshold value, the supply of air is stopped once by closing the electromagnetic valve 6 or turning off the electromagnetic switch 7. Next, when the remaining fuel gas in the fuel gas supply line 21 and the air in the air electrode layer 13 generate power and the voltage rises again and becomes higher than the threshold value, the electromagnetic valve 6 is opened or the electromagnetic switch 7 By turning ON, the process of supplying air is repeated.

  Finally, when the voltage does not become higher than the threshold value, the supply of air is stopped by closing the electromagnetic valve 6 or turning off the electromagnetic switch 7.

Next, a method of stopping operation when the air blower 4 of the solid oxide fuel cell power generation apparatus having the above configuration fails will be described.
First, the air remaining in the air buffer tank 3 is supplied to the air electrode layer 13.

  When the voltage of the solid oxide fuel cell 2 becomes lower than a predetermined threshold value, the supply of air is stopped once by closing the electromagnetic valve 6. Next, when a power generation reaction is caused by the residual fuel gas in the fuel gas supply line 21 and the air in the air electrode layer 13 and the voltage rises again to become higher than the threshold value, the solenoid valve 6 is opened to open the air The process of supplying is repeated.

  Finally, when the voltage does not become higher than the threshold value, the supply of air is stopped by closing the electromagnetic valve 6.

  According to the method for stopping the operation of the solid oxide fuel cell power generator having the above-described configuration, the air blower 4 is operated by the storage battery 7 or the system power supply 10 to supply air to the air buffer tank 3. 2, after the air pressure is stabilized, the air is supplied to the air electrode layer 13, so that the remaining fuel gas flows into the fuel electrode layer, and oxygen ions of the oxidant gas are Even if it moves to the fuel electrode layer, oxygen ions of the oxidant gas continue to be supplied to the oxidant electrode layer, so that it is possible to prevent a change in the crystal structure of the oxidant electrode layer. As a result, it is possible to prevent the power generation performance of the solid oxide fuel cell 2 from being deteriorated even after restarting after an emergency stop.

  Further, when the voltage of the solid oxide fuel cell 2 becomes lower than a predetermined threshold value by the electromagnetic valve 6 or the electromagnetic switch 7, the supply of air is once stopped and the voltage is increased again to increase the voltage. When the voltage is higher than the threshold value, the process of supplying air is repeated, and when the voltage does not eventually become higher than the threshold value, the supply of air is stopped. The amount can be minimized, and the air buffer tank 3 can be downsized.

  Furthermore, since the time for supplying air is also reduced, it is possible to reduce the power for operating the air blower 4 during an emergency stop, and it is possible to mount the storage battery 9 with a small capacity. .

  As a result, the solid oxide fuel cell power generator can be reduced in size.

(Example 1)
In Example 1, a solid oxide fuel cell 2 in which a power generation reaction is performed using the above-described solid oxide fuel cell power generator in which 40 layers of single cells 18 each having a power generation cell 14 having a diameter of 120 mm are stacked. The load current, fuel gas supply, and air supply were stopped once to make a virtual complete power failure, and then the air in the air buffer tank 3 was set to a flow rate of 5 NLM and supplied to the air electrode layer 13. When the voltage of the solid oxide fuel cell 2 becomes lower than 4V, the valve body of the electromagnetic valve 6 is closed and the supply of the air is stopped once, and the voltage rises again and becomes higher than 4V. Then, the step of opening the valve body of the electromagnetic valve 6 and supplying the air is repeated, and when the voltage does not eventually become higher than 4V, the valve body of the electromagnetic valve 6 is closed and the supply of the air is performed. Stopped. And the time (cumulative) which supplied air until the supply of the said air stopped was measured.

  In Example 1, the solid electrolyte layer 11 made of lanthanum gallate material (LSGMC) to which strontium, magnesium, and cobalt are added, the fuel electrode layer 12 made of Ni cermet, and the samarium strontium cobaltite (SSC). Since the solid oxide fuel cell 2 in which 40 layers of the single cell 18 using the φ120 mm power generation cell 14 constituted by the air electrode layer 13 is stacked is used, the threshold of the solid oxide fuel cell is set to 4 V (in the cell voltage) 0.1V), the total voltage differs depending on the number of solid oxide fuel cells installed, the number of stacked single cells, and the material and size of the power generation cell. It is necessary to set the threshold value to a value suitable for each solid oxide fuel cell.

  Here, as a comparative example 1, after using a conventional solid oxide fuel cell power generation device to make a virtual complete power failure as described above, the air in the air buffer tank is set to a flow rate of 5 NLM and air When the supply to the extreme layer was continued and the voltage of the solid oxide fuel cell 2 became lower than 4V, the supply of the air was stopped. And the air supply time until the said air supply stopped was measured.

  As a result, the air supply time of Example 1 was 10 minutes, and the air supply time of Comparative Example 1 was 40 minutes.

  As a result, the air buffer tank 3 of the solid oxide fuel cell power generator according to Example 1 is supplied for 10 minutes with the air flow rate set to 5 NLM. In this case, it was confirmed that a buffer tank with a capacity of 5 L (= 5 NLM × 10 min ÷ 10 atm) can be used.

  On the other hand, since the air buffer tank of the solid oxide fuel cell power generator of Comparative Example 1 is set at an air flow rate of 5 NML and supplied for 40 minutes, the buffer tank pressure is temporarily filled with 10 atm. It was confirmed that it was necessary to use a buffer tank with a capacity of 20 L (= 5 NML × 40 min ÷ 10 atm).

  As a result, the solid oxide fuel cell power generator supplies air by the air buffer tank 3 at least when the supply of the fuel gas stops and makes an emergency stop, and the voltage of the solid oxide fuel cell 2 by the electromagnetic valve 6. Is once lower than a predetermined threshold value, the air supply is once stopped, and when the voltage rises again and becomes higher than the threshold value, the step of supplying air is repeated, and finally the above-mentioned When the voltage is no longer higher than the above threshold, the supply of air can be minimized by stopping the supply of air, and the air buffer tank can be downsized. I was able to prove that.

(Example 2)
In the second embodiment, the air buffer tank 3 of the solid oxide fuel cell power generation apparatus of the first embodiment is changed to an air blower 4 and the electromagnetic valve 6 is changed to an electromagnetic switch 7 to operate under the same operating conditions. The stopping method was performed. And the power consumption until supply of air stopped was measured.

  On the other hand, Comparative Example 2 used the conventional solid oxide fuel cell power generator as in Comparative Example 1, and changed the air buffer tank to an air blower and performed an operation stop method under the same operating conditions. And the power consumption until supply of air stopped was measured. However, the rated power of the air blower is 20 W, and the power consumption when operated for 1 h is 20 Wh.

  Since the storage battery 9 of the solid oxide fuel cell power generator according to the second embodiment is set at an air flow rate of 5 NLM and is supplied for 10 minutes, a battery with a capacity of 3.33 Wh (= 20 Wh × 1 / 6h) is used. It was confirmed that it was usable.

  In addition, since the storage battery of the solid oxide fuel cell power generator of Comparative Example 2 is set for an air flow rate of 5 NLM and supplied for 40 minutes, the capacity is 13.3 Wh (= 20 Wh × 2 / 3h). It was confirmed that it was necessary to use.

  As a result, the solid oxide fuel cell power generator supplies air by the air blower 4 at least when the supply of the fuel gas stops and makes an emergency stop, and the voltage of the solid oxide fuel cell 2 by the electromagnetic switch 7. Is once lower than a predetermined threshold value, the air supply is once stopped, and when the voltage rises again and becomes higher than the threshold value, the step of supplying air is repeated, and finally the above-mentioned When the voltage does not become higher than the above threshold value, by stopping the supply of air, it is possible to reduce the power for operating the air blower 4 in the event of a complete power failure, and the storage battery 9 having a small capacity. It was proved that it would be possible to install.

  In this embodiment, as the oxidant gas supply means, the oxidant gas supply unit 5 in which the air blower 4 is provided at the front stage of the air buffer tank 3 is used. However, the present invention is not limited to this, and air can be supplied. If it is a thing, even if it installs only the air buffer tank 3 single-piece | unit or only the air blower 4 single-piece | unit in the solid oxide fuel cell electric power generating apparatus, the electromagnetic valve 6 is provided in the air buffer tank 3, and the air blower 4 is provided. By providing the electromagnetic switch 7, the amount of air supply can be minimized.

  In the present embodiment, the threshold value is set based on the voltage of the solid oxide fuel cell 2, but it is also possible to set the threshold value based on the cell voltage of the single cell 18.

2 Solid oxide fuel cell 3 Air buffer tank (oxidant gas buffer tank)
4 Air blower (oxidizer gas blower)
5 Oxidant gas supply unit 6 Solenoid valve (Oxidant gas supply control means)
7 Electromagnetic switch (oxidant gas supply control means)
9 Battery 12 Fuel electrode layer 13 Air electrode layer (oxidant electrode layer)
21 Fuel gas supply line 22a Oxidant gas supply line 22b Oxidant gas supply line

Claims (4)

A fuel gas is supplied to the fuel electrode layer, and an oxidant gas is supplied to the oxidant electrode layer to generate a power generation reaction, and a fuel gas that supplies the fuel gas to the fuel electrode layer A supply line, and an oxidant gas supply means for supplying an oxidant gas, and an oxidant gas supply line for supplying the oxidant gas obtained by the oxidant gas supply means to the oxidant electrode layer. ,
The oxidant gas supply means supplies the oxidant gas to the oxidant electrode layer based on a threshold voltage of the solid oxide fuel cell at least when supply of the fuel gas is stopped and an emergency stop is performed. An oxidant gas supply control means for controlling whether or not to supply the solid oxide fuel cell power generator is provided.   The oxidant gas supply control means and the oxidant gas supply means are each provided with a storage battery that partially stores electric power obtained by a power generation reaction of the solid oxide fuel cell. 2. The solid oxide fuel cell power generator according to 1.   The oxidant gas supply means comprises an oxidant gas blower or a compressor provided at the front stage of an oxidant gas buffer tank that stabilizes the pressure of the oxidant gas and supplies it to the solid oxide fuel cell. The solid oxide fuel cell power generator according to claim 1 or 2, wherein A method for stopping operation of a solid oxide fuel cell according to claim 1,
At least when the supply of the fuel gas is stopped and an emergency stop is performed, the oxidant gas supply unit supplies an oxidant gas to the oxidant electrode layer, and the oxidant gas supply control means controls the solid oxide fuel. When the voltage of the battery becomes lower than a predetermined threshold value, the supply of the oxidant gas is once stopped, and when the voltage rises again and becomes higher than the threshold value, the supply of the oxidant gas is stopped. A method of stopping operation of a solid oxide fuel cell, characterized in that the supply of the oxidant gas is stopped when the steps to be performed are repeated and the voltage does not eventually become higher than the threshold value.