JP2007103124A - Control method of fuel cell power generation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control method of a fuel cell power generation system, wherein at a time of the start up of a fuel cell stack under the condition that oxidant electrode is filled with hydrogen during a shutdown storing, start up can be operated without causing catalyst deterioration of the catalyst layer of the oxidant electrode. <P>SOLUTION: A fuel cell stack 1, a reforming unit 3, an oxidant gas supply means 24 and an inert gas purge means 26 to the oxidant electrode are provided. The reforming unit 3 is warmed at start up, and the inert gas purge means 26 is started up so that substitution of the inert gas is completed by the time the warming up of the reforming unit 3 is completed, and an operation of the reforming unit 3 is started, as soon as the inert gas purge means 26 is stopped, when the warming up of the refroming unit 3 is completed, and thus a start up of a fuel cell stack 1 is controlled. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a control method for a fuel cell power generation system using a polymer electrolyte fuel cell.

  A polymer electrolyte fuel cell is a fuel cell that uses a solid polymer membrane as an electrolyte. Hydrogen or a hydrogen-containing gas that is a fuel gas at the fuel electrode and oxygen or an oxygen-containing gas that is an oxidant gas at the oxidant electrode (usually This is a device that converts the reaction energy of hydrogen and oxygen directly into electric energy and takes it out at an electrode catalyst layer in which a catalyst of platinum fine particles is supported on carbon at each electrode (fuel electrode and oxidant electrode). In the catalyst layer of each electrode, the reaction shown in the following formula occurs. At this time, the hydrogen supplied to the fuel electrode is decomposed into electrons and hydrogen ions at the fuel electrode, the electrons pass through an external circuit, and the hydrogen ions move through the solid polymer membrane (electrolyte) to the oxidant electrode. It reacts with oxygen supplied to the oxidizer electrode.

Fuel electrode reaction H ₂ → 2H ⁺ + 2e ⁻ (1)
Oxidant electrode reaction ^{_{1 / 2O 2 + 2H + +}} 2e - → H 2 O (2)
Since the electromotive force of a single battery (single cell) sandwiching a solid polymer membrane between a pair of fuel electrode and oxidizer electrode is as low as about 1V, a plurality of single cells are practically connected in series. A fuel cell stack having a structure capable of collectively supplying fuel gas and oxidant gas is used. The fuel cell power generation system includes a fuel cell stack that is a fuel cell main body, a fuel gas supply unit that supplies a fuel gas to a fuel electrode of the fuel cell stack, an oxidant supply unit that supplies an oxidant to an oxidant electrode, It consists of a power converter that converts the electric output of the fuel cell stack into a form that can be supplied to an external load, and a control device that controls these devices. Usually, air is used as the oxidant gas, and an air blower is used as the oxidant supply means. As the fuel gas supply means, a reformer is used that generates a fuel gas, which is a hydrogen-containing gas, by reacting raw fuel such as city gas or kerosene and raw water with a catalyst. A temperature of about 700 ° C. is required for the reforming reaction, and a warm-up operation of about one hour is required until the reformer reaches an operating condition that enables generation of fuel gas.

  The polymer electrolyte fuel cell is considered to be easy to handle in an ordinary household because the electrolyte is solid and easy to handle and can be easily reduced in size and weight. When used for general households, DSS (Daily Start & Stop) operation is required to start and stop once a day, such as during the daytime and stop at night when power demand is low. In DSS operation, it is known that the performance of the fuel cell stack deteriorates faster than in continuous operation. As one of the causes, it is conceivable that platinum fine particles or carbon that constitute the catalyst layer of the oxidant electrode due to oxygen existing in the oxidant electrode during stop storage and oxidative deterioration of carbon or aggregation of the platinum fine particles.

  To prevent this, stop the fuel cell operation after stopping the supply of fuel gas to the fuel electrode and the air supply to the oxidizer electrode during the stop operation and consuming and removing oxygen in the oxidizer electrode. Then, a method is disclosed in which the oxidant electrode is purged with hydrogen gas, which is a reducing gas, the fuel electrode and the oxidant electrode are filled with a hydrogen-containing gas, sealed, and stored in a stopped state (for example, Patent Documents). 1). Although the fuel cell stack is operated at 60 to 80 ° C. during power generation, the temperature of the fuel cell stack decreases after the stop, so that the gas pressure in the fuel electrode and the oxidant electrode also decreases and becomes negative with respect to the atmospheric pressure. Become. Therefore, even if the fuel electrode and the oxidizer electrode are sealed, it is difficult to completely prevent the intake of air (oxygen) from the seal portion. However, for example, even when a small amount of oxygen enters the communication space of the oxidant electrode from the outside, the oxidant electrode is filled with hydrogen gas and stored, so that oxygen reacts with hydrogen in the catalyst layer of the oxidant electrode. The communication space of the oxidizer electrode is maintained in a hydrogen atmosphere. Therefore, as long as there is hydrogen in the oxidizer electrode, the catalyst does not deteriorate. Similarly, even when a small amount of oxygen enters the communication space of the fuel electrode from the outside, the fuel electrode is also filled with hydrogen gas and stored, so that deterioration of the catalyst is prevented.

Japanese Patent Laid-Open No. 2002-93448 (page 5, FIG. 1)

  In a conventional stop storage method, so-called hydrogen-filled stop storage method, hydrogen gas exists in the fuel electrode and the oxidant electrode of the fuel cell stack when the fuel cell power generation system is started. There is no problem if fuel gas is supplied to the fuel electrode for power generation in this state. However, if air is supplied to the oxidant electrode, oxygen and hydrogen in the air cause a direct exothermic reaction due to catalytic action, and the catalyst Heated. There is no problem if the amount of air to be supplied is small, but there is a problem that when a large amount of air is supplied as in power generation, a large amount of heat is generated, the temperature of the catalyst layer rises and the catalyst deteriorates.

  The present invention has been made in order to solve the above-described problems. When the fuel cell stack is started in a state where the oxidant electrode is filled with hydrogen in the stopped storage state, the catalyst of the catalyst layer of the oxidant electrode is used. It is an object of the present invention to provide a control method for a fuel cell power generation system that can be activated without causing deterioration.

  A control method for a fuel cell power generation system according to the present invention includes a fuel cell stack, a reformer, an oxidant gas supply means, and an inert gas purge means for an oxidant electrode, and warms up the reformer at startup. When the reformer warm-up operation is completed, start the oxidant electrode inert gas purge to complete the reformer warm-up operation. At times, the inert gas purging means of the oxidizer electrode is stopped and the reformer is started to perform control to start power generation of the fuel cell stack.

  According to the present invention, when the fuel cell power generation system is started in a state where the oxidant electrode of the fuel cell stack is kept in a hydrogen atmosphere during stop storage, the fuel cell stack can be started without causing catalyst deterioration of the catalyst layer of the oxidant electrode. It becomes possible to prevent the performance deterioration of the fuel cell power generation system due to the start and stop.

Embodiment 1 FIG.
FIG. 1 is a schematic diagram showing a configuration of a fuel cell power generation system according to Embodiment 1 for carrying out the present invention. Normally, the fuel cell stack 1 is configured by laminating a plurality of single cells, but in FIG. 1, the fuel cell stack 1 is shown as a single cell configuration for ease of explanation. A fuel gas supply hole 2 for supplying fuel gas to the fuel electrode 1a and a fuel gas outlet 4 of the reformer 3 as fuel gas supply means are connected via fuel gas supply valves 5 through fuel gas supply conduits 6a and 6b. Has been. The fuel gas exhaust hole 7 for exhausting the fuel off-gas from the fuel electrode 1a of the fuel cell stack 1 and the combustion burner inlet 8 of the reformer 3 are connected via a fuel gas exhaust valve 9 by fuel gas exhaust conduits 10a and 10b. Has been. The raw fuel inlet 13 and the raw fuel supply means 14 of the reformer 3 are connected by a raw fuel supply conduit 16 via a raw fuel valve 15, and between the raw fuel supply means 14 and the raw fuel supply valve 15. The raw fuel supply conduit 16 branches and is connected to the start burner inlet 19 of the reformer 3 via the start burner fuel supply valve 17 and the start burner fuel supply conduit 18. A raw water supply means 20 is connected to the raw fuel supply conduit 16 between the raw fuel supply valve 15 and the raw fuel inlet 13. The raw water supply means 20 is a device that injects a certain proportion of water into the raw fuel, and includes a pump and a flow meter. An oxidant supply hole 21 for supplying air, which is an oxidant, to the oxidant electrode 1b of the fuel cell stack 1 is provided with an oxidant supply conduit 23a, 23b via an oxidant supply valve 22 and an air blower 24 as oxidant supply means. A nitrogen supply means 26 is connected to an oxidant supply conduit 23 a between the oxidant supply hole 21 and the oxidant supply valve 22 through a nitrogen supply valve 25. The nitrogen supply means 26 is, for example, a nitrogen gas cylinder or a nitrogen production apparatus. An oxidant exhaust hole 27 that is an exhaust hole for air off-gas from the oxidant electrode 1b of the fuel cell stack 1 is connected to an exhaust hole (see FIG. (Not shown). Although not shown, in order to keep the temperature of the fuel cell stack 1 during power generation at a constant temperature of 60 to 80 ° C., the fuel cell stack 1 is provided with a heating and cooling device. The electrical output terminals 30 a and 30 b of the fuel cell stack 1 are connected to the power converter 32 via the switch 31, and the output of the power converter 32 is connected to the external load 33. The power converter 32 includes a converter and an inverter that convert voltage and frequency so that the electric output of the fuel cell stack 1 can be consumed by an external load. Although not shown, each component device such as the fuel cell stack 1, the reformer 3, and the fuel gas supply valve 5, the conduit, and the wiring are provided with sensors such as temperature, pressure, flow rate, current, and voltage. In addition, the control signal of each component device and the sensor signal 43 of each sensor are input / output to / from the control device 42, and each component device is controlled by the control device 42.

  Next, an operation method during power generation in this embodiment will be described. During steady operation, the reformer 3 receives supply of raw fuel and raw water such as city gas, LPG (liquefied propane gas) and kerosene from the raw fuel supply means 14 and the raw water supply means 20, and fuel gas. The fuel gas is generated by reforming into a hydrogen-containing gas. In order to reform the raw fuel into fuel gas by the reformer 3, it is necessary to maintain the reformer 3 at a temperature of about 700 ° C. and the energy required for reforming. Fuel off-gas is used. The fuel gas generated in the reformer passes through the fuel gas outlet 4, the fuel gas supply conduit 6a, the fuel gas supply valve 5, the fuel gas supply conduit 6b, and the fuel gas supply hole 2, and passes through the fuel electrode 1a of the fuel cell stack 1. To be supplied. Of the supplied fuel gas, the fuel gas that has not contributed to the reaction passes through the fuel gas exhaust pipe 10a, the fuel gas exhaust valve 9 and the fuel gas exhaust pipe 10b from the fuel gas exhaust hole 7 as fuel off-gas, and enters the combustion burner inlet 8 To the reformer 3. The fuel off-gas supplied to the reformer 3 is burned by a combustion burner, and is used for maintaining the temperature of the reformer 3 and supplying thermal energy necessary for reforming. Air is supplied from the air blower 24 to the oxidant electrode 1b of the fuel cell stack 1 through the oxidant supply conduit 23b, the oxidant supply valve 22, and the oxidant supply conduit 23a. The air that has not contributed to the reaction at the oxidant electrode 1b is discharged from the system through the oxidant exhaust hole 27 as the air off-gas through the oxidant exhaust conduit 29a, the oxidant exhaust valve 28, and the oxidant exhaust conduit 29b. During steady operation, the nitrogen supply valve 25 is closed. The electrical output obtained from the electrical output terminals 30a and 30b of the fuel cell stack 1 is supplied to the power converter 32 through the switch 31 in the ON state, converted into an appropriate voltage and frequency, and consumed by the external load 33.

  Although the above-described operation is an operation at the time of steady operation, a start-up operation is required to bring the stopped fuel cell power generation system into a steady operation state. The main starting operation is the warm-up operation of the reformer 3. Since the temperature of the reformer 3 in the stopped fuel cell power generation system is about the outside air temperature, the reformer 3 normally operates up to the operating temperature (about 700 ° C.) at which the fuel gas that is a hydrogen-containing gas is generated from the raw fuel. There is a need for warm-up operation to raise the temperature of the reformer 3. During steady operation, the start burner fuel supply valve 17 is closed to utilize the combustion of the fuel off-gas for maintaining the temperature of the reformer 3, but the fuel is still not used in the warm-up operation in which the temperature of the reformer is raised from the system stop state. Since off-gas cannot be used, the starting burner fuel supply valve 17 is opened and the raw fuel is directly burned by the starting burner. After the temperature of the reformer 3 is raised to an operating temperature of about 700 ° C., the raw water is supplied, and finally the raw fuel is supplied to obtain the fuel gas from the reformer 3. When the fuel gas is supplied to the fuel cell stack 1 and the fuel off-gas becomes available, the start burner fuel supply valve 17 is closed and the routine shifts to a steady operation.

  Next, an operation method at the time of stop in the present embodiment will be described. In such a fuel cell power generation system, in order to apply the hydrogen enclosure stop storage method, first, the oxidant supply valve 22 and the oxidant exhaust valve 28 are closed while the supply of fuel gas to the fuel electrode 1a is continued. Air supply to the pole 1b is stopped. At this time, consumption of the power generation output of the fuel cell stack 1 at the external load 33 is continued with the power converter 32 being operated. As a result, the oxygen in the oxidant electrode 1b is consumed and removed, and when the oxygen is almost lost in the oxidant electrode 1b, hydrogen is transferred from the fuel electrode 1a to the oxidant electrode 1b due to the hydrogen partial pressure difference between the fuel electrode 1a and the oxidant electrode 1b. Moves electrochemically, and the oxidant electrode 1b is also filled with the hydrogen-containing gas. In this state, the fuel gas supply valve 5 and the fuel gas exhaust valve 9 are closed to stop the fuel gas supply to the fuel electrode 1a, and other components are stopped to stop the entire fuel cell power generation system. As a result, the fuel cell stack 1 is stopped and stored in the communication space of the fuel electrode 1a, that is, the fuel gas supply conduit 6a between the fuel gas supply valve 5 and the fuel gas exhaust valve 9, the fuel electrode 1a space, and the fuel. The space of the gas exhaust conduit 10a is filled with the hydrogen-containing gas, and the fuel gas supply valve 5 and the fuel gas exhaust valve 9 are closed. On the other hand, the communication space of the oxidant electrode 1b, that is, the oxidant supply conduit 23a from the oxidant supply valve 22 to the oxidant exhaust valve 28, the space of the oxidant electrode 1b, and the space of the oxidant exhaust conduit 29a are also filled with hydrogen-containing gas. Thus, the oxidant supply valve 22 and the oxidant exhaust valve 28 are closed.

  In order to operate the fuel cell power generation system from the stopped storage state as described above, hydrogen in the communication space of the oxidant electrode 1b of the fuel cell stack 1 (hereinafter simply referred to as the oxidant electrode 1b unless misunderstood). Therefore, it is conceivable to replace the oxidizer electrode 1b with an inert gas such as nitrogen (nitrogen purge) before starting. In the fuel cell power generation system of FIG. 1, the hydrogen supply stop storage method is used to stop storage, the nitrogen supply valve 25 and the oxidant exhaust valve 28 are opened before startup, and nitrogen gas is allowed to flow from the nitrogen supply means 26 to the oxidant electrode 1b. A DSS operation was performed in which nitrogen purge was performed to remove hydrogen from the oxidizer electrode 1b and power generation was started. However, it was found that the power generation output at the time of start-up is lower than the power generation output just before the stop, and as a result, the expected effect of preventing catalyst deterioration cannot be obtained. A hydrogen sensor is experimentally installed in the communication space between the fuel electrode 1a and the oxidant electrode 1b, and it has been confirmed that hydrogen exists in the communication space between the fuel electrode 1a and the oxidant electrode 1b before activation. In addition, since it has been confirmed that hydrogen has disappeared in the communication space of the oxidizer electrode 1b after the nitrogen purge of the oxidizer electrode 1b, both electrodes at the time of stopped storage are held in a hydrogen atmosphere, and it is unlikely that the catalyst will deteriorate in the catalyst. In addition, since there is no hydrogen in the communication space of the oxidant electrode 1b at the start of power generation, the catalyst cannot be deteriorated at high temperature due to a direct reaction between air and hydrogen. That is, when starting the fuel cell power generation system stored in a state where the fuel electrode 1a and the oxidant electrode 1b are filled with the hydrogen-containing gas, the oxidant electrode is purged with the inert gas to reliably remove hydrogen. Nevertheless, catalyst deterioration could not be completely prevented.

  In order to elucidate the cause, the output voltage of the fuel cell stack 1 was analyzed in detail during the nitrogen purge of the oxidizer electrode 1b performed at startup. As a result, the output voltage of the fuel cell stack 1 is zero until the nitrogen purge of the oxidant electrode 1b is performed, but when the nitrogen purge of the oxidant electrode 1b is started, the output voltage of the fuel cell stack 1 becomes the normal voltage. It was found to occur with the same polarity as during power generation. Moreover, it has been found that the output voltage once generated decreases only slightly even if the nitrogen purge is continued. It can be estimated from this that oxygen is not present near the catalyst layer of the oxidant electrode 1b before the nitrogen purge of the oxidant electrode 1b, and oxygen is present near the catalyst layer when the nitrogen purge is performed.

  As described above, the nitrogen purge of the oxidant electrode 1b is performed by opening the nitrogen supply valve 25 and the oxidant exhaust valve 28, from the nitrogen supply unit 26 to the nitrogen supply valve 25, the oxidant supply conduit 23a, the oxidant electrode 1b, Nitrogen is allowed to flow through the oxidant exhaust conduit 29 a and the oxidant exhaust valve 28. Therefore, oxygen appears in the vicinity of the catalyst layer of the oxidant electrode 1b by the nitrogen purge of the oxidant electrode 1b because oxygen exists upstream of the oxidant electrode 1b in the communication space of the oxidant electrode 1b. This suggests that the oxygen was swept away by the purge and reached the catalyst layer of the oxidizer electrode 1b. In the case of stopping by the above hydrogen enclosure stop storage method, oxygen in the communication space of the oxidant electrode 1b is consumed and removed by the power generation reaction after the supply of air is stopped. Further, even if air enters the oxidant electrode 1b during stop storage, it is removed by reacting with hydrogen in the electrode catalyst layer, and the communication space of the oxidant electrode 1b is maintained in a hydrogen atmosphere. Even oxygen in a space away from the electrode catalyst layer does not remain for several hours in view of the gas diffusion rate.

  For the above reasons, it is unlikely that oxygen remains upstream of the communication space of the oxidant electrode 1b during the nitrogen purge of the oxidant electrode 1b. The possibility that oxygen trapped in the inner wall of the oxidant electrode 1b communication space and condensed water was released cannot be denied, and above all, from the behavior of the output voltage of the fuel cell stack 1 during the nitrogen purge of the oxidant electrode 1b, I must admit the presence of residual oxygen.

  If residual oxygen is present in the upstream space of the oxidant electrode 1b during the nitrogen purge, the storage method and the start method during the DSS operation are respectively the hydrogen filling stop storage method and the start method for purging the oxidant electrode 1b with nitrogen before the start. The reason why the catalyst has deteriorated even if is applied can be explained as follows.

  At start-up, oxygen in the upstream space of the oxidant electrode 1b is swept away by the nitrogen purge and reaches the catalyst layer. Part of the oxygen that has reached the catalyst layer reacts with hydrogen by the catalytic action and is removed. However, because the hydrogen concentration in the vicinity of the catalyst layer is reduced by the nitrogen purge, some oxygen has no hydrogen to react. Adsorbs to carbon and platinum fine particles in the catalyst layer. Since the adsorbed oxygen is a reduction reaction potential, an output voltage appears in the fuel cell stack 1, and the oxygen adsorbed on the catalyst layer cannot be easily removed even if the nitrogen purge is continued, and the output voltage of the fuel cell stack 1 is also quite high. It does not decline. Therefore, the catalyst layer of the oxidant electrode 1b is exposed to a high potential, and oxidative degradation and coagulation degradation occur. Oxygen adsorbed on the catalyst layer of the oxidant electrode 1b can be effectively removed only electrochemically, that is, by a power generation reaction. Therefore, the catalyst layer of the oxidant electrode 1b continues to deteriorate until the power generation of the fuel cell stack 1 is started. To do. In addition, since the fuel cell stack 1 is heated to the operating temperature in preparation for the start of power generation, the catalyst deterioration rate is fast. In some cases, the catalyst deterioration of the oxidizer electrode proceeds, and catalyst deterioration during DSS operation cannot be prevented.

  From the above test results and considerations, in order to prevent catalyst deterioration in DSS operation, when hydrogen storage stop storage method is applied as the storage method, and nitrogen purge method that removes hydrogen from the oxidizer electrode 1b is adopted as the startup method Furthermore, the need for a technique for avoiding catalyst deterioration due to residual oxygen in the communication space of the oxidant electrode 1b became clear.

  FIG. 2 is an explanatory diagram of a start-up procedure in the present embodiment, and shows a method of starting the fuel cell power generation system shown in FIG. 1 from a state where it is stopped and stored by the hydrogen filling stop storage method. The state before starting, that is, the state when the fuel cell stack 1 is stopped and stored is the communication space of the fuel electrode 1a, that is, the fuel gas supply conduit 6a between the fuel gas supply valve 5 and the fuel gas exhaust valve 9, and the fuel electrode 1a. The space of the fuel gas exhaust conduit 10a is filled with the hydrogen-containing gas, and the fuel gas supply valve 5 and the fuel gas exhaust valve 9 are closed. The communication space of the oxidant electrode 1b, that is, the space of the oxidant supply conduit 23a, the oxidant electrode 1b and the oxidant exhaust conduit 29a between the oxidant supply valve 22 and the oxidant exhaust valve 28 is also filled with the hydrogen-containing gas. The oxidant supply valve 22 and the oxidant exhaust valve 28 are closed. The starting procedure of the fuel cell power generation system from this state will be described with reference to FIG.

  First, in step 1, in order to generate the fuel gas supplied to the fuel electrode 1a by reforming from the raw fuel, the warm-up operation of the reformer 3 is started. For this purpose, an opening command is sent from the control device 42 to the starting burner fuel supply valve 17, and at the same time, a starting burner ignition command is sent to the reformer 3. Thereby, the start burner of the reformer 3 starts combustion, and the temperature rise of the reformer 3 starts. Normally, the temperature required for the reformer 3 and the reforming temperature are about 700 ° C., and the warm-up operation of about 1 hour is required from the start burner ignition until the operating conditions of the reformer 3 are adjusted and the fuel gas can be supplied. is necessary.

  After starting Step 1, the control device 42 monitors a signal from a temperature sensor (not shown) provided in the reformer 3, and if the temperature of the reformer 3 satisfies a predetermined temperature condition, Step 2 Then, an open command is sent to the nitrogen supply valve 25 and the oxidant exhaust valve 28, and an operation command is sent to the nitrogen supply means 26. Nitrogen gas is allowed to flow through the oxidant electrode 1b to start nitrogen purge. After starting the temperature raising of the reformer 3 in step 1, the temperature of the reformer 3 gradually rises. The time characteristic of this temperature rise is substantially the same if the initial state of the reformer 3 is the same, and after reaching a certain intermediate point temperature, it reaches the final operating temperature and the warm-up operation is completed, That is, the necessary warm-up operation time t1 is reproducible. Obviously, the required warm-up operation time t1 depends on the temperature of the reformer 3 at the intermediate point. On the other hand, the time required for performing the nitrogen purge of the oxidant electrode 1b and replacing the hydrogen in the communication space of the oxidant electrode 1b with nitrogen, that is, the necessary purge time t2, is also the volume of the communication space of the oxidant electrode 1b. If the flow rate of nitrogen used for purging is constant, there is reproducibility. Therefore, if an appropriate purge flow rate is selected, there exists a temperature T during the warm-up operation of the reformer 3 such that the required warm-up time t1 = the required purge time t2. The condition that the temperature of the reformer 3 satisfies the predetermined temperature condition means that the reformer 3 has reached the intermediate temperature T. That is, if the nitrogen purge of the oxidizer electrode 1b is started when the reformer 3 reaches the temperature T, the temperature of the reformer 3 reaches the operating temperature, and the warm-up operation in which the fuel gas can be supplied to the fuel electrode 1a. Almost simultaneously with completion, the nitrogen replacement of the oxidizer electrode 1b is completed. The temperature condition of the reformer 3, that is, the reformer temperature T, is experimentally obtained in advance from the time t2 required for nitrogen replacement in the communication space of the oxidizer electrode 1b and the time characteristics when the reformer 3 is heated. deep.

  Next, when the reformer 3 reaches the operating temperature, as step 3, the control device 42 sends a close command to the nitrogen supply valve 25 and a stop command to the nitrogen supply means 26 to finish the nitrogen purge of the oxidizer electrode 1b. Since the nitrogen purge is started in advance so that the nitrogen replacement of the oxidant electrode 1b is completed at the same time when the reformer 3 can supply the fuel gas, the oxidant electrode 1b remains nitrogen even if the nitrogen purge is finished here. Has been replaced. In step 3, as soon as the nitrogen purge is completed, an open command is sent to the raw fuel valve 15, the fuel gas supply valve 5, and the fuel gas exhaust valve 9, and supply of reformed gas, that is, fuel gas, to the fuel electrode 1a is started. When the fuel off-gas is supplied to the combustion burner inlet 8 of the reformer 3 and an ignition signal of the combustion burner is detected, a closing command is sent to the start burner fuel supply valve 17.

  Next, in step 4, an operation command is sent from the control device 42 to the air blower 24, and an open command is sent to the oxidant supply valve 22. At this time, fuel gas is supplied to the fuel electrode 1a of the fuel cell stack 1 and air is supplied to the oxidant electrode 1b, and an open circuit voltage is generated between the electric output terminals 30a and 30b of the fuel cell stack 1.

  Next, in step 5, an ON command is sent to the switch 31, an operation command is sent to the power converter 32, and power generation is started. Thereafter, the output is increased and the rated operation is performed.

  In the fuel cell power generation system configured as described above, the control device 42 operates each component device according to the procedure described above to start the fuel cell power generation system. Before the air is supplied, the oxidant electrode 1b is substituted with nitrogen, and there is no direct reaction between oxygen and hydrogen, and there is no catalyst heating. In addition to this effect, oxygen staying in the oxidant electrode 1b communication space upstream of the oxidant electrode 1b, that is, in the oxidant supply conduit 23a or the like by the nitrogen purge of the oxidant electrode 1b is pushed out to the oxidant electrode 1b by the purge and becomes the catalyst layer Even if the adsorption is performed, the purge can be immediately terminated and the power generation can be started as soon as the reformer 3 can supply the fuel gas, so that the oxygen adsorption time to the oxidant electrode 1b can be reduced to a short time, and the oxidant electrode 1b. It is possible to suppress oxidative degradation of the catalyst layer and aggregation degradation due to a high potential.

  In this embodiment, the timing of the nitrogen purge start of the oxidizer electrode 1b is measured based on the temperature condition of the reformer 3. For example, step 2 is performed at the time after the start of the temperature increase of the reformer 3. Alternatively, it may be the time when the total amount of raw fuel supplied to the starting burner of the reformer 3 after the start of temperature rise reaches a certain value, or reforming that increases as the temperature of the reformer 3 rises. It may be the time when the pressure of the gas outlet 4 reaches a certain value. No matter what timing the nitrogen purge of the oxidant electrode 1b is started, it is possible to realize a condition in which the replacement of the oxidant electrode 1b with nitrogen and the time when the fuel gas can be supplied to the reformer 3 can be realized. Good.

  Further, in the present embodiment, nitrogen is used as an inert gas for purging the oxidant electrode 1b. However, if it is inert to the constituent material, catalyst and hydrogen of the fuel cell stack, carbon dioxide or rare Gas may be used.

Embodiment 2. FIG.
FIG. 3 is an explanatory diagram showing a control procedure of the fuel cell power generation system in the second embodiment. In the present embodiment, the fuel cell power generation system includes a timer in the control device 42 and controls activation using this timer. The configuration of the fuel cell power generation system is the same as that of the first embodiment. The control procedure at the time of starting will be described with reference to FIG. Step 1 is the start of raising the temperature of the reformer 3 as in the first embodiment. The reformer 3 is heated by the start burner, but the control device 42 monitors the status of the reformer 3 with a sensor, and when a preset reformer condition is satisfied, the timer is set as t2 in step 2. Set to 0. As the reformer conditions, for example, the temperature of the reformer or the time point at which the raw water is charged into the reformer can be adopted as in the first embodiment. The time from when the reformer conditions are satisfied until the reformer operating conditions are met, that is, the time until fuel gas can be supplied is obtained in advance, and this time is defined as T1. For example, in the case of a fuel cell power generation system with generated power of 1 kW, if the reformer conditions set in advance are used as the reformer temperature and the reformer temperature is 80 ° C., T1 is about 30 minutes. On the other hand, a time from the start of the nitrogen purge of the oxidant electrode 1b to the completion of the nitrogen replacement of the oxidant electrode 1b is obtained in advance, and this time is defined as T2. For example, the oxidant electrode 1b communication space is determined in advance from the flow rate of nitrogen during nitrogen purge and the volume of the oxidant electrode 1b communication space (oxidant supply conduit 23a, oxidant electrode 1b, and oxidant exhaust conduit 29a). It is also possible to obtain the time T2 necessary for replacing nitrogen with the following equation.

T2 = (communication space volume of oxidizer electrode) / (nitrogen flow rate) (3)
This time T2 is a time necessary for filling the communication space of the oxidant electrode 1b with nitrogen, and hydrogen existing in at least the space of the communication space of the oxidant electrode 1b is excluded from the communication space of the oxidant electrode 1b. It is time necessary for. For example, in the case of a fuel cell power generation system with generated power of 1 kW, if the volume of the communication space of the oxidizer 1b is several liters and the flow rate of the nitrogen purge is several liters / minute, the communication space of the oxidizer 1b is replaced with nitrogen. The time T2 required to do this is within 1 minute. Therefore, it is considered that the majority of hydrogen can be eliminated by performing a nitrogen purge for at least time T2.

  As Step 3, when the timer reaches t = t1, the controller 42 sends an open command to the nitrogen supply valve 25 and the oxidant exhaust valve 28, sends an operation command to the nitrogen supply means 26, and causes nitrogen gas to flow through the oxidant electrode 1b. Start purging. The time t1 at which the nitrogen purge is started is a preset time that satisfies t1 ≦ T1-T2.

  When the timer reaches t = t2 = T1 in step 4, the control device 42 sends a close command to the nitrogen supply valve 25 and a stop command to the nitrogen supply means 26 to finish the nitrogen purge of the oxidizer electrode 1b, and the raw fuel valve 15. An open command is sent to the fuel gas supply valve 5 and the fuel gas exhaust valve 9 to start supplying fuel gas to the fuel electrode 1a. When the fuel off-gas is supplied to the combustion burner inlet 8 of the reformer 3 and an ignition signal of the combustion burner is detected, a closing command is sent to the start burner fuel supply valve 17. Next, in step 5, an operation command is sent from the control device 42 to the air blower 24 and an open command is sent to the oxidant supply valve 22. At this time, fuel gas is supplied to the fuel electrode 1a and air is supplied to the oxidant electrode 1b, and an open circuit voltage is generated between the electric output terminals 30a and 30b of the fuel cell stack 1.

  Next, in step 6, an ON command is sent to the switch 31, an operation command is sent to the power converter 32, and power generation is started. Thereafter, the output is increased and the rated operation is performed.

  In the fuel cell power generation system configured as described above, in Step 3, the time from the start of the nitrogen purge of the oxidant electrode 1b to the end of the nitrogen purge of the oxidant electrode 1b in Step 4, that is, the oxidant electrode 1b is purged with nitrogen. Since at least the T2 (= t2−t1) time is exceeded, at least hydrogen existing in the communication space of the oxidizer electrode 1b is removed. Therefore, when the reformer becomes capable of supplying fuel gas, the nitrogen purge is completed, and power generation can be started immediately. Therefore, the oxygen adsorption time to the catalyst layer of the oxidant electrode 1b can be reduced to a short time, and immediately. Even when the power generation is started, hydrogen and oxygen are not mixed in the oxidant electrode 1b, so that it is possible to suppress catalyst deterioration and coagulation deterioration due to temperature rise of the catalyst layer of the oxidant electrode 1b.

  As the reformer conditions, the temperature of the reformer and the raw water supply time can be adopted, but the temperature rising start time of Step 1 may be adopted. However, if the time from when the reformer conditions are satisfied until the fuel gas can be supplied becomes long, the error increases. Therefore, it is desirable to set the reformer conditions as close as possible to the time when the fuel gas can be supplied. In this respect, the feed of raw material water is most convenient because it is possible to supply the fuel gas immediately. Also, when the reformer temperature is set as the reformer condition, it is desirable to set the temperature just before the reforming temperature.

  Further, in the present embodiment, as a method for obtaining the time T2 from the start of the nitrogen purge of the oxidant electrode 1b to the completion of the nitrogen substitution, an example is calculated from the communication space volume of the oxidant electrode 1b and the nitrogen purge flow rate. Although shown, the time T2 may be obtained by actually measuring the time from when the nitrogen purge is performed until the hydrogen concentration in the exhaust gas of the oxidant exhaust conduit 29b is no longer detected.

Embodiment 3 FIG.
FIG. 4 is a schematic diagram showing the configuration of the fuel cell power generation system in the third embodiment. In the present embodiment, a resistance load 35 is connected between the electric output terminals 30 a and 30 b of the fuel cell stack 1 via the switch 34 in parallel with the power converter 32. Other configurations are the same as those in the first embodiment. The state at the time of start-up after stop storage is that the communication space of the fuel electrode 1a, that is, the fuel gas supply conduit 6a between the fuel gas supply valve 5 and the fuel gas exhaust valve 9, the space of the fuel electrode 1a and the fuel gas exhaust conduit 10a. The fuel gas supply valve 5 and the fuel gas exhaust valve 9 are closed while being filled with the hydrogen-containing gas. Further, the communication space of the oxidant electrode 1b, that is, the oxidant supply conduit 23a from the oxidant supply valve 22 to the oxidant exhaust valve 28, the space of the oxidant electrode 1b, and the space of the oxidant exhaust conduit 29a are filled with hydrogen-containing gas. In this state, the oxidant supply valve 22 and the oxidant exhaust valve 28 are closed. Further, the switch 34 is ON, and the electric output of the fuel cell stack 1 is connected to the resistance load 35.

  The hydrogen in the communicating space of the oxidant electrode 1b during stop storage is consumed by reacting with oxygen not removed at the time of stoppage or oxygen in the atmosphere entering from the outside during storage and the catalyst layer of the oxidant electrode 1b. When the hydrogen in the oxidant electrode 1b is not consumed, the catalyst layer of the oxidant electrode 1b is exposed to oxygen and deteriorates. However, if the electrical output of the fuel cell stack 1 is connected to the resistance load 35 during stop storage as in the present embodiment, if the hydrogen on the oxidizer electrode 1b side is consumed and the hydrogen partial pressure decreases, the fuel electrode A difference from the hydrogen partial pressure on the 1a side is generated, and an electric current flows through the resistance load 35 due to the electromotive force due to this partial pressure difference, and hydrogen moves electrochemically from the fuel electrode 1a to the oxidant electrode 1b. As a result, the hydrogen atmosphere of the oxidant electrode 1b can be maintained using the hydrogen of the fuel electrode 1a. Conversely, when the amount of hydrogen in the fuel electrode 1a decreases, the hydrogen moves from the oxidant electrode 1b to the fuel electrode 1a, and hydrogen can be accommodated in both electrodes, so that the catalyst layers on both electrodes are reliably prevented from being oxidized during storage. be able to.

  In the fuel cell power generation system in such a stopped storage state, this embodiment shows a startup method. FIG. 5 is an explanatory diagram showing a control procedure of the fuel cell power generation system in the present embodiment. As shown in FIG. 5, before starting the nitrogen purge of the oxidizer electrode 1b in step 3, as a step 2, an OFF command is sent to the switch 34 to disconnect the electrical output of the fuel cell stack 1 from the resistance load 35, and the fuel cell Free the stack output. Control in subsequent steps, start and end timing of nitrogen purge of the oxidizer electrode 1b, start of power generation, and the like are the same as in the first or second embodiment. Even if the control is performed in such a configuration, the effect of preventing the deterioration of the catalyst layer of the oxidant electrode 1b at the time of start-up can be obtained as in the first or second embodiment.

  When the oxidant electrode 1b is purged with nitrogen while the electric output of the fuel cell stack 1 is connected to the resistance load 35, the catalyst layer of the fuel electrode is deteriorated if the fuel electrode 1a has a small amount of hydrogen. That is, when oxygen that has accumulated in a space such as the oxidant supply conduit 23a by nitrogen purge is pushed out to the oxidant electrode 1b and reaches the catalyst layer of the oxidant electrode 1b, part of it reacts with hydrogen in the oxidant electrode 1b. However, a part of the output of the fuel cell stack 1 is connected to the resistance load 35, causing a cell reaction and consuming hydrogen in the fuel electrode 1a. As a result, when there is little hydrogen of the fuel electrode 1a, the fuel electrode 1a will be in a fuel-deficient state, and the catalyst layer of the fuel electrode 1a will deteriorate. Further, when the oxidant electrode 1b is purged with nitrogen, the hydrogen in the oxidant electrode 1b is removed and the hydrogen partial pressure is lowered. Therefore, hydrogen moves electrochemically from the fuel electrode 1a to the oxidant electrode 1b. Also in this case, if the hydrogen in the fuel electrode 1a is small, the fuel becomes insufficient and the catalyst layer of the fuel electrode 1a deteriorates. On the other hand, if the start-up control shown in FIG. 5 is performed, in order to release the output of the fuel cell stack 1 before the nitrogen purge of the oxidant electrode 1b is started, the fuel depletion at the fuel electrode 1a as described above is caused. Therefore, deterioration of the fuel electrode 1a catalyst can be prevented.

  As in the present embodiment, the oxidant electrode 1b and the fuel electrode 1a are closed in a hydrogen atmosphere, the output of the fuel cell stack 1 is resistance-connected and stored, and before starting, the oxidant electrode 1b is purged with nitrogen. If the output of the fuel cell stack 1 is opened at the same time, it is easy to maintain the hydrogen atmosphere of the oxidant electrode 1b during stop storage (because hydrogen of the fuel electrode 1a can be used), and the oxidant electrode 1b during startup. During the nitrogen purge, hydrogen on the fuel electrode 1a side is not consumed, so that the fuel electrode 1a does not run out of fuel, and catalyst deterioration during start / stop storage can be more reliably prevented.

Embodiment 4 FIG.
In the third embodiment, a method for preventing fuel depletion of the fuel electrode 1a when the amount of hydrogen in the fuel electrode 1a is small at the time of start-up is shown. However, in the fourth embodiment, a start-up method when there is sufficient hydrogen in the fuel electrode 1a. Show. The configuration of the fuel cell power generation system in the present embodiment is the same as that in the third embodiment.

  FIG. 6 is an explanatory diagram showing a control procedure of the fuel cell power generation system in the present embodiment. In the present embodiment, with the output of the fuel cell stack 1 connected to the resistance load 35, the oxidant electrode 1b is purged with nitrogen, and at least the output of the fuel cell stack 1 before the start of power generation is connected to the power converter 32. Before starting, an OFF command is sent to the switch 34 in step 4 to disconnect the output of the fuel cell stack 1 from the resistance load 35. Other operations are the same as those in the first and second embodiments. Oxygen staying in the space such as the oxidant supply conduit 23a due to the nitrogen purge is pushed out to the oxidant electrode 1b and reaches the oxidant electrode 1b catalyst, and a part thereof is adsorbed on the catalyst layer of the oxidant electrode 1b. However, since there is sufficient hydrogen in the fuel electrode 1a and the output of the fuel cell stack 1 is connected to the resistance load 35, oxygen adsorbed on the catalyst layer of the oxidant electrode 1b due to the cell reaction is absorbed by the fuel electrode 1a. Reacts with hydrogen and is removed. As a result, since the oxidizer electrode 1b is kept at a low potential, the catalyst layer does not deteriorate.

  As described above, in the present embodiment, the hydrogen atmosphere of the oxidant electrode 1b of the fuel cell stack 1 is easily maintained during storage (because hydrogen of the fuel electrode 1a can be used) as in the third embodiment. In addition, it is possible to prevent adsorption of oxygen to the catalyst layer of the oxidant electrode 1b due to nitrogen purge of the oxidant electrode 1b at the time of start-up, and further prevent deterioration of the oxidant electrode 1b catalyst at the time of start-up.

  In this embodiment, the output of the fuel cell stack 1 is opened at least before being connected to the power converter 32. However, it is preferable that the output is performed at the end of the nitrogen purge, that is, in step 3. If the oxidant electrode 1b is purged with nitrogen, the oxidant electrode 1b is depleted of hydrogen, and electrochemically moves from the fuel electrode 1a to the oxidant electrode 1b. Therefore, if the output of the fuel cell stack 1 is connected to the resistance load 35 even after the nitrogen purge is completed, the oxidant electrode 1b becomes a hydrogen atmosphere again, depending on the duration of the connection. This is because there is a possibility.

Embodiment 5. FIG.
In the fourth embodiment, when the oxidant electrode 1b is purged with nitrogen, the adsorption of oxygen to the catalyst layer of the oxidant electrode 1b can be prevented and the catalyst can be prevented from deteriorating. However, the hydrogen partial pressure of the oxidant electrode 1b due to the nitrogen purge can be prevented. Since the hydrogen moves electrochemically from the fuel electrode 1a to the oxidant electrode 1b due to the decrease in the hydrogen concentration, the hydrogen concentration in the oxidant electrode 1b may not be lowered unless the nitrogen flow rate during the nitrogen purge is increased. The fifth embodiment is a control method for reliably reducing the hydrogen concentration of the oxidizer electrode 1b.

  FIG. 7 is an explanatory diagram showing a control procedure of the fuel cell power generation system in the present embodiment. In step 1, the reformer temperature rise is started, and in step 2, the nitrogen purge of the oxidizer electrode 1b is started. In the nitrogen purge of the oxidant electrode 1b, air staying in the upstream side of the nitrogen purge flow from the oxidant electrode 1b, that is, in the space such as the oxidant supply conduit 23a is pushed out to the oxidant electrode 1b, and a part of the oxidant electrode 1b. Adsorbed to the catalyst, the output of the fuel cell stack 1 is connected to the resistance load 35, so that a cell reaction occurs, a part reacts with the hydrogen present in the oxidant electrode 1b, and a part of the oxidant exhausts together with the hydrogen. It is exhausted through valve 28 and removed. That is, after the air staying in the oxidant supply conduit 23a or the like is pushed out to the oxidant electrode 1b, only the nitrogen gas passes through the oxidant electrode 1b. An OFF command is sent, the resistance load 35 is disconnected, and the output of the fuel cell stack 1 is opened. As a result, oxygen is no longer carried to the catalyst layer of the oxidant electrode 1b, so that oxygen is not adsorbed by the catalyst layer of the oxidant electrode 1b and the output of the fuel cell stack 1 is released. Even if the hydrogen on the oxidant electrode 1b side is removed, there is no electrochemical hydrogen movement from the fuel electrode 1a side, and it becomes easy to purge the hydrogen on the oxidant electrode 1b side even when the nitrogen flow rate of purge is small. . The time point at which the output of the fuel cell stack 1 in step 3 is released is determined experimentally in advance, or the fact that the output voltage of the fuel cell stack 1 decreases if the adsorbed oxygen in the catalyst layer of the oxidant electrode 1b is removed. May be detected.

  According to the present embodiment, as in the fourth embodiment, it is possible to prevent the electrode catalyst deterioration due to the start and stop, and further, the nitrogen purge for removing the hydrogen of the oxidizer electrode 1b becomes easier than in the fourth embodiment. There is.

Embodiment 6 FIG.
FIG. 8 is a schematic diagram showing the configuration of the fuel cell power generation system in the sixth embodiment. In the present embodiment, as shown in FIG. 8, the pressure replenishing means 11 is connected to the fuel gas supply conduit 6 a between the fuel gas supply hole 2 and the fuel gas supply valve 5 of the fuel cell stack 1 via the pressure replenishment valve 12. Connected. The pressure replenishing means 11 is a device that compensates for the pressure drop in the communicating space, and is adjusted to release, for example, a gas reservoir whose volume changes in accordance with the pressure increase or decrease in the communicating space, or a pressure drop in the communicating space. A gas container connected to a pressure reducing valve (regulator). The gas is replenished if the pressure of the fuel electrode 1a decreases by adjusting the output pressure of the regulator slightly positive. As the gas used here, nitrogen, carbon dioxide, or the like that is inert to the catalyst or structure of the fuel cell or the fuel gas can be used. The nitrogen supplied from the nitrogen supply means 26 for purging the oxidant electrode 1b may be supplied by a regulator. Other configurations are the same as those of the third embodiment.

  In the first to fifth embodiments, when the oxidant electrode 1b is purged with nitrogen during startup, a phenomenon occurs in which the pressure on the fuel electrode 1a side decreases. This is because when the output of the fuel cell stack 1 is connected to the resistance load 35, hydrogen on the fuel electrode 1a side is electrochemically moved to the oxidant electrode 1b by purging the oxidant electrode 1b. This is because a pressure drop of 1a occurs. Even if the output of the fuel cell stack 1 is opened, if the hydrogen partial pressure of the oxidant electrode 1b is reduced by the nitrogen purge on the oxidant electrode 1b side, a difference in hydrogen partial pressure between the fuel electrode 1a and the oxidant electrode 1b occurs. This is because, since the hydrogen permeability of the electrolyte membrane is not zero, hydrogen movement occurs through the electrolyte membrane due to a difference in hydrogen partial pressure, and as a result, the pressure of the fuel electrode 1a decreases. When the pressure of the fuel electrode 1a is reduced to atmospheric pressure or lower due to the pressure drop, air enters from the seal portion such as the fuel cell stack 1 or a conduit and the fuel electrode 1a catalyst is deteriorated.

  FIG. 9 is an explanatory diagram showing the control procedure of the fuel cell power generation system in the present embodiment. Before starting the nitrogen purge of the oxidizer electrode 1b, in step 2, an opening command is sent to the pressure replenishing valve 12, an operation command is sent to the pressure replenishing means 11, and the fuel electrode 1a and the pressure replenishing means are connected to each other in the communication space of the fuel electrode 1a. Start pressure refill. When the nitrogen purge of the oxidizer electrode 1b is completed, a close command is sent to the pressure replenishing valve 12 and a stop command is sent to the pressure replenishing means 11, and the pressure refilling of the fuel electrode 1a space is finished. Other controls are the same as in the third embodiment. As a result, the pressure drop of the fuel electrode 1a can be compensated when the nitrogen purge of the oxidant electrode 1b is performed, and the intrusion of air into the fuel electrode 1a can be prevented. While preventing the catalyst layer of the agent electrode 1b from being deteriorated, it is also possible to prevent catalyst deterioration of the fuel electrode 1a due to a pressure drop of the fuel electrode 1a. Note that the pressure replenishing means 11 and the pressure replenishing valve 12 can be used not only for starting but also for replenishing the pressure drop of the fuel electrode 1a due to the temperature drop of the fuel cell stack 1 during stop storage. In this case, the pressure replenishing valve 12 is open and the pressure replenishing means 11 is in operation during stop storage of the fuel cell power generation system, and step 2 can be omitted because pressure replenishment is always performed during stop storage.

  In the first to sixth embodiments, the reformer is described as an example of the fuel gas supply means. However, the fuel cell power generation system to which the present invention can be applied is not limited to the reformer. . If it is a fuel gas supply means that requires time for power generation preparation of the fuel cell stack, if the present invention is applied when applying the hydrogen enclosure stop storage method, it is possible to prevent catalyst deterioration due to start-up stop.

1 is a schematic diagram showing a fuel cell power generation system according to Embodiment 1 of the present invention. It is explanatory drawing which shows the control means by Embodiment 1 of this invention. It is explanatory drawing which shows the control means by Embodiment 2 of this invention. It is a schematic diagram which shows the fuel cell power generation system by Embodiment 3 of this invention. It is explanatory drawing which shows the control means by Embodiment 3 of this invention. It is explanatory drawing which shows the control means by Embodiment 4 of this invention. It is explanatory drawing which shows the control means by Embodiment 5 of this invention. It is a schematic diagram which shows the fuel cell power generation system by Embodiment 6 of this invention. It is explanatory drawing which shows the control means by Embodiment 6 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Fuel cell stack, 1a Fuel electrode, 1b Oxidant electrode, 2 Fuel gas supply hole, 3 Reformer, 4 Fuel gas outlet, 5 Fuel gas supply valve, 6a, 6b Fuel gas supply conduit, 7 Fuel gas exhaust hole, 8 Combustion burner inlet, 9 Fuel gas exhaust valve, 10a, 10b Fuel gas exhaust conduit, 11 Pressure supplement means, 12 Pressure supplement valve, 13 Raw fuel inlet, 14 Raw fuel supply means, 15 Raw fuel valve, 16 Raw fuel supply conduit 17 Start burner fuel supply valve, 18 Start burner fuel supply conduit, 19 Start burner inlet, 20 Raw water supply means, 21 Oxidant supply hole, 22 Oxidant supply valve, 23a, 23b Oxidant supply conduit, 24 Air blower, 25 Nitrogen supply valve, 26 Nitrogen supply means, 27 Oxidant exhaust hole, 28 Oxidant exhaust valve, 29a, 29b Oxidant exhaust conduit, 30a, 30b Electric output Terminal, 31 switch, 32 Power converter, 33 External load, 34 switch, 35 Resistive load, 42 Control device, 43 Control signal and sensor signal

Claims (8)

A fuel cell stack;
An oxidant gas supply means for supplying an oxidant gas to the oxidant electrode of the fuel cell stack;
Fuel gas supply means for supplying fuel gas to the fuel electrode of the fuel cell stack;
A reformer for generating the fuel gas;
A control method of a fuel cell power generation system comprising an inert gas purge means for replacing the oxidant electrode with an inert gas,
Start warm-up operation for raising the temperature of the reformer to the operating temperature at startup, and complete the replacement of the inert gas into the oxidizer electrode when the warm-up operation of the reformer is completed Control that starts the inert gas purge means, stops the inert gas purge means when the warm-up operation of the reformer is completed, starts operation of the reformer, and starts power generation of the fuel cell stack A control method for a fuel cell power generation system. After the start of the warm-up operation of the reformer, the time from when the reformer reaches a preset condition until the reformer starts to supply the fuel gas is T1, and from the start of the inert gas purge means The time until the replacement of the inert gas at the oxidizer electrode is completed is T2, and after the start of the warm-up operation of the reformer, the time after the reformer reaches the preset condition (T1-T2) 2. The method of controlling a fuel cell power generation system according to claim 1, wherein the replacement of the oxidant with an inert gas is started before progress. 3. The control method for a fuel cell power generation system according to claim 2, wherein time from when the temperature of the reformer reaches a predetermined value until the reformer starts to supply fuel gas is T1. 3. The control method for a fuel cell power generation system according to claim 2, wherein the time from when the raw material water supply to the reformer is started until the reformer starts to supply fuel gas is T1. A load resistance connectable to the electric output of the fuel cell stack is provided, the electric output of the fuel cell stack is connected to the load resistance during stop storage, and the fuel cell before starting the replacement of the inert gas of the oxidant electrode at the start-up The control method of the fuel cell power generation system according to any one of claims 1 to 4, wherein the connection between the electrical output of the stack and the load resistance is cut off. A load resistance connectable to the electrical output of the fuel cell stack is provided, the electrical output of the fuel cell stack is connected to the load resistance during stop storage, and after the replacement of the inert gas of the oxidant electrode at the start-up, the fuel cell stack The control method of the fuel cell power generation system according to any one of claims 1 to 4, wherein a connection between the electrical output of the battery and the load resistance is cut off. A load resistance connectable to the electrical output of the fuel cell stack, the electrical output of the fuel cell stack is connected to the load resistance during stop storage, and the start before the end of replacement of the inert gas of the oxidant electrode at the start-up The method for controlling a fuel cell power generation system according to any one of claims 1 to 4, wherein a connection between an electric output of the fuel cell stack and the load resistance is cut off. The pressure replenishing means is provided between the fuel electrode and the fuel gas supply means, and the fuel replenishing means keeps the fuel electrode at atmospheric pressure or higher by the pressure replenishing means when the inert gas in the oxidant electrode is replaced. 8. A control method for a fuel cell power generation system according to any one of claims 7 to 9.

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