JP2008201650A - Hydrogen generating apparatus, fuel cell system and method for operating hydrogen generating apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that when air enters into a CO remover in a hydrogen generating apparatus during long-term stopping and a catalyst is oxidized, the oxidized catalyst reaches a high temperature in the next start and causes sintering. <P>SOLUTION: A hydrogen generating apparatus is provided comprising: a reformer 1 for generating a hydrogen-containing gas by a reforming reaction of raw material; a CO remover 3 for reducing the CO content of the hydrogen-containing gas sent from the reformer 1 by an oxidation reaction; an air feeder 3 which feeds an oxidizing gas to the CO remover 3; a third temperature sensor 9 which senses the temperature of the CO remover 3; and a control unit 15, wherein the control unit 15 makes beginning of feed of air from the air feeder 3 in start later than that in usual start when the temperature sensed by the third temperature sensor 9 is higher than the temperature in usual start. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a hydrogen generator, a fuel cell system that generates power using hydrogen generated by the hydrogen generator, and an operation method thereof.

  A polymer electrolyte fuel cell (PEFC) generates power using oxygen and hydrogen. The industrial production method of hydrogen includes electrolysis of water, and other methods include a steam reforming method of hydrocarbon gas, a partial oxidation method, and an autothermal method combining the both. These reforming methods reform methane, ethane, propane, butane, city gas, LP gas, and other hydrocarbon gases (including mixed gases of two or more hydrocarbons) to produce hydrogen-rich hydrogen-containing gases. In either case, a reformer is used.

  The carbon monoxide (CO) content in the fuel hydrogen supplied to the PEFC is limited to about 50 ppm (capacity, hereinafter the same), and if it exceeds this, the battery performance is significantly deteriorated. Therefore, it is necessary to remove CO as much as possible before introducing it into PEFC, and it is desirable that CO be 10 ppm or less.

  The hydrogen-containing gas produced in the steam reforming contains unreacted methane, unreacted steam and carbon dioxide, and usually by-produced CO of about 8 to 15% (volume, the same applies hereinafter). For this reason, the hydrogen-containing gas is introduced into the transformer to remove by-product CO. In the transformer, CO is converted into carbon dioxide gas and hydrogen by the transformation reaction (Equation 1).

(Formula 1) CO + H ₂ O → CO ₂ + H ₂
Even in the hydrogen-containing gas delivered from the transformer, CO is not completely removed, and a trace amount of CO is contained. For this reason, an oxidant gas such as air is added, and CO is reduced to 50 ppm or less, preferably 10 ppm or less by the CO oxidation reaction (formula 2) in the CO remover.

(Formula 2) CO + 1 / 2O ₂ → CO ₂
The purified hydrogen-rich hydrogen-containing gas is supplied to the PEFC anode. In general, a Ru / Al ₂ O ₃ catalyst is excellent and widely used as an oxidation catalyst capable of removing CO concentration to a low concentration (10 ppm or less) in a wide temperature range (see, for example, Non-Patent Document 1). .

Further, when the hydrogen generator is shut down, there is usually a method of purging a residual gas containing hydrogen inside with a raw material gas, filling a space in the hydrogen generator with the raw material gas, and then shutting off communication with outside air. It has been proposed (see, for example, Patent Documents 1 and 2).
SH Oh, RM Sinkevitch, J. Catal, 142 (1993) 254. JP 2003-288930 A JP 2004-307236 A

  However, if the hydrogen generator is provided with a shut-off valve as described in the above-mentioned patent document and the inside is filled with the raw material gas, the air may be mixed if the seal is insufficient even if shut off from the outside air There is.

  Also, when the hydrogen generator is not used for a long period of time, the pressure inside the device becomes negative with respect to atmospheric pressure due to changes in the external environment (atmospheric pressure, temperature) and air is mixed in, or the seal deteriorates over time. May be mixed in.

As described above, if air is mixed into the hydrogen generator, the oxidation catalyst (for example, Ru / Al ₂ O ₃ oxidation catalyst) of the CO remover is oxidized and deteriorated. The reduction reaction proceeds by the hydrogen-containing gas supplied from the reformer, and the oxidation catalyst temperature is increased by the heat of the reduction reaction, which may cause problems such as sintering. In particular, when the oxidation catalyst is a Ru / Al ₂ O ₃ catalyst, when the catalyst temperature exceeds 200 to 250 ° C., methanation of CO and CO ₂ with H ₂ proceeds, and the catalyst temperature rapidly increases.

  Thus, even if the inside of the apparatus is replaced with a non-oxidizing gas and stopped without problems in a sealed state, and no obvious abnormality is detected as an apparatus even during the stop period, for various reasons The oxidation catalyst of the CO remover may be oxidized and deteriorated. In this case, if the startup operation is performed as usual, there is a possibility of causing sintering due to high temperature as described above.

  In consideration of the problems of the conventional hydrogen generator, the present invention provides an abnormality related to the oxidative degradation of the oxidation catalyst as a device before the start-up operation is started even though the oxidation catalyst is oxidatively degraded. It is an object of the present invention to provide a hydrogen generator, a fuel cell system, and an operation method thereof that can be stably started even when no is detected.

In order to achieve the above object, the hydrogen generator of the first aspect of the present invention comprises:
A reformer for generating a hydrogen-containing gas by a reforming reaction of the raw material; a CO remover for reducing carbon monoxide in the hydrogen-containing gas delivered from the reformer by an oxidation reaction; and the CO An oxidant gas supply unit that supplies an oxidant gas to the remover, a temperature detector that detects a temperature of the CO remover, and a controller, wherein the controller detects a temperature detected by the temperature detector at the time of startup. When the temperature is higher than the normal startup temperature, the start of the supply of the oxidizing gas from the oxidizing gas supply device is delayed from the normal startup time.

The second hydrogen generator of the present invention is
When the controller is activated at a time when the temperature detected by the temperature detector is equal to or higher than the first threshold is earlier than normal, the controller starts the supply of the oxidizing gas from the oxidizing gas supplier more than at the normal activation. It is characterized by delaying.

Moreover, the hydrogen generator of the third aspect of the present invention is:
When the controller detects that the temperature detected by the temperature detector becomes equal to or higher than the second threshold value at a specific timing, the controller starts delaying the supply of the oxidizing gas from the oxidizing gas supplier compared to the normal startup. It is characterized by that.

The hydrogen generator of the fourth aspect of the present invention is
The controller may start supplying the oxidizing gas from the oxidizing gas supply device when the temperature detected by the temperature detector decreases and becomes a third threshold value or less.

Moreover, the hydrogen generator of the fifth aspect of the present invention is:
The controller starts supplying the oxidizing gas from the oxidizing gas supplier, and then the oxidizing gas is detected when a temperature detected by the temperature detector becomes equal to or higher than a fourth threshold value that is larger than the third threshold value. The supply of the oxidizing gas from the supply device is stopped.

The sixth aspect of the hydrogen generator of the present invention is:
The controller stops supplying the oxidizing gas from the oxidizing gas supplier, and then supplies the oxidizing gas when the temperature detected by the temperature detector becomes equal to or lower than a fifth threshold value that is smaller than the fourth threshold value. The supply of the oxidizing gas from the vessel is restarted.

The fuel cell system of the seventh aspect of the present invention is
The hydrogen generator of the present invention and a fuel cell that generates power using the hydrogen-containing gas supplied from the hydrogen generator.

  In addition, the operation method of the hydrogen generator according to the eighth aspect of the present invention includes a reformer for generating a hydrogen-containing gas by a raw material reforming reaction, and monoxide in the hydrogen-containing gas sent from the reformer. A hydrogen generator comprising: a CO remover for reducing carbon by an oxidation reaction; an oxidizing gas supplier for supplying an oxidizing gas to the CO remover; and a temperature detector for detecting the temperature of the CO remover. In the operation method, at the time of start-up, if the temperature detected by the temperature detector is higher than the temperature at the time of normal start-up, control is performed so that the start of supply of the oxidizing gas from the oxidizing gas supply device is delayed from that at the time of normal start-up. It is characterized by performing.

  According to the present invention, even though the oxidation catalyst of the CO remover is oxidized and deteriorated, no abnormality related to the oxidation deterioration of the oxidation catalyst is detected as a device until the start-up operation is started. Even so, it is possible to provide a hydrogen generator, a fuel cell system, and an operation method thereof that can be stably started.

  Hereinafter, a fuel cell system according to an embodiment of the present invention will be described, and an example of a hydrogen generator of the present invention will be described at the same time.

(Embodiment 1)
FIG. 1 is a schematic configuration diagram of a fuel cell system according to Embodiment 1 of the present invention. As shown in FIG. 1, the fuel cell system according to Embodiment 1 includes a hydrogen generator 11 that generates a hydrogen-rich hydrogen-containing gas. The hydrogen generator 11 includes a reformer 1 filled with a reforming catalyst that generates a hydrogen-rich hydrogen-containing gas containing CO from a raw material gas containing hydrocarbons and water.

  Further, the hydrogen generator 11 includes a transformer 2 in which a pellet-like Pt / CeZrOx catalyst is filled on the downstream side of the reformer 1 with reference to the gas flow direction. In this transformer 2, CO generated as a by-product in the reformer 1 is reduced. Further, a first heating unit 4 for heating the shift catalyst at the time of start-up and a first temperature detector 16 for detecting the temperature of the shift converter 2 are provided. In the present embodiment, a sheath heater is used as the first heating unit 4.

  Further, the hydrogen generator 11 includes a CO remover 3 filled with a Ru / alumina catalyst as an oxidation catalyst on the downstream side of the transformer 2. In the CO remover 3, CO that cannot be removed by the transformer 2 is further reduced. Further, a second heating unit 8 is provided upstream of the CO remover 3 to heat the gas supplied to the CO remover 3. In the present embodiment, a sheath heater is used as the second heating unit 8. In addition, a second temperature detector 6 is provided downstream of the second heating unit 8 in order to measure the gas temperature upstream of the CO remover 3. A third temperature detector 9 that detects the catalyst temperature is provided in contact with the oxidation catalyst of the CO remover 3.

  Further, a cooling unit (not shown) for cooling the periphery of the CO remover 3 with an air cooling fan is provided. Note that an air supply device 5 as an oxidizing gas supply device of the present invention for supplying air as an oxidizing gas to the CO removing device 3 is connected to a gas flow path between the transformer 2 and the CO removing device 3. Yes. Examples of the air supplier 5 include an air supply blower.

  A polymer electrolyte fuel cell 7 (PEFC), which is an example of a fuel cell, is installed on the downstream side of the CO remover 3 to generate electricity using a hydrogen-containing gas with sufficiently reduced CO as an anode gas. . Examples of the anode catalyst of the polymer electrolyte fuel cell 7 include Pt—Ru / C. The gas containing hydrogen remaining without being consumed at the anode of the polymer electrolyte fuel cell 7 is dehumidified and then supplied as an anode off-gas to the burner 12 of the reformer 1 through the anode off-gas passage 10 for combustion. 1 is used for heating.

  Further, a switching valve 14 is provided between the CO remover 3 and the polymer electrolyte fuel cell 7 so that the gas flowing out from the CO remover 3 is supplied to the burner 12 side or the PEFC side. It is the structure switched so that it may flow in. The anode off-gas passage 10 is provided with a condenser (not shown) so that water vapor is condensed and combustion can be stably performed by the burner 12.

  Further, based on the second temperature detector 6, the third temperature detector 9, and the first temperature detector 16, the burner 12, the first heating unit 4, the air supply unit 5, the second heating unit 8, and A control unit 15 for controlling the switching valve 14 is provided.

  An example of the reformer of the present invention corresponds to the reformer 1 of the present embodiment, and an example of the CO remover of the present invention corresponds to the CO remover 3 of the present embodiment. An example of the oxidizing gas supply device of the present invention corresponds to the air supply device 5 of the present embodiment, and an example of the temperature detector of the present invention corresponds to the third temperature detector 9 of the present embodiment. . An example of the controller of the present invention corresponds to the control unit 15 of the present embodiment.

  Next, the operation of the fuel cell system of the present embodiment will be described, and an example of the operation method of the hydrogen generator of the present invention will also be described.

  FIG. 2 is a graph showing a catalyst temperature detected by the third temperature detector 9 at the time of start-up in the fuel cell system of the present embodiment. FIG. 3 is a flow chart showing the starting operation of the fuel cell system according to the present embodiment. When the fuel cell system according to the present embodiment is stopped, the city gas 13A is purged, and the city gas 13A is sealed in the hydrogen generator, and then the operation is stopped.

  First, a normal startup operation of the fuel cell system will be described.

  This normal start-up operation is a start-up operation of the fuel cell system in the case where the oxidation deterioration of the oxidation catalyst has not progressed until the start-up operation is started. In FIG. 2, the catalyst temperature in this normal start-up operation is indicated by a solid line.

  At start-up (S0), first, while purging the hydrogen generator 11 with the city gas 13A, the switching valve 14 is switched to the bypass path 13 side, and the reformer 1 is heated by the burner 12. At the same time, the transformer 2 and the CO remover 3 are heated by the first heating unit 4 and the second heating unit 8, respectively (S1).

Next, the control unit 15, the time becomes the threshold T ₁ is performed early or late or determination than the time t _a which is stored in advance (S2). The thresholds T ₁ is a temperature suitable for oxidation reaction, for example, a 100 ° C., t _a can be set to 40 minutes. The time t _a, at the time of startup in the case where oxidation of the oxidation catalyst is not in progress, a time earlier than the time the catalyst temperature becomes thresholds T _1, activation operation after the start of the time to reach thresholds T ₁ There is earlier than t _a is the high possibility that the oxidation catalyst is oxidized values.

Therefore, in the normal startup, as shown in FIG. 2, the time t ₁ in which the catalyst temperature becomes thresholds T ₁ which predetermined detected by the third temperature detector 9, slower than the time t _a, the following Proceed to step 3.

Next, when the reformer 1 reaches a predetermined temperature (t ₃ ), the control unit 15 operates the air supplier 5 to supply air to the CO remover 3 (S3). The time t ₃ when the reformer 1 reaches a predetermined temperature, a fixed time, for example, can be set to 50 minutes from the start of activation. In addition, time _{t 3} is made generally slower than the time _{t a.} The predetermined temperature is 550 ° C. Incidentally, an example of the supply start of the normal startup of the oxidizing gas of the present invention corresponds to the time t ₃ of the present embodiment.

  After the air supply, the CO concentration is sufficiently reduced, and then the CO remover 3 outlet gas is switched to the polymer electrolyte fuel cell 7 side (S4), and power generation is started.

  The temperatures detected by the first temperature detector 16 of the transformer 2 and the second temperature detector 6 of the CO remover 3 are monitored, and the first temperature detector 16 or the second temperature detector 6 is monitored. When the detected temperature reaches a predetermined temperature (for example, 175 ° C.) or higher, both heaters are set to be turned off.

  Next, the start-up operation of the fuel cell system will be described in the case where no obvious abnormality that causes the oxidative deterioration is detected as a device even though the oxidation catalyst has been oxidized and deteriorated before the start-up operation is started.

  In the present embodiment, it is assumed that air enters the apparatus and the oxidation catalyst is deteriorated by oxidation due to changes in the surrounding environment during a long-term stoppage.

  In FIG. 2, a change with time of the catalyst temperature in the start-up operation after the oxidation catalyst is oxidized and deteriorated during the long-term stop period is indicated by a one-dot chain line.

The operation of the fuel cell system up to step 1 (S1) is the same as the normal startup operation. In Step 2 (S2), the time in which the catalyst temperature is _{T 1} is _{t 2,} since earlier than the time _{t 2} is the time _{t a,} unlike the normal startup operation, the process proceeds to step 5. Here, when the oxidation catalyst is oxidatively deteriorated, when the hydrogen-containing gas is introduced, the catalyst is heated to a higher temperature than the start-up when the oxidation catalyst is not oxidatively deteriorated due to the reduction reaction of ruthenium oxide. Therefore, if the time the catalyst temperature becomes T ₁ is earlier than t _a can determine that there is a high possibility that the oxidation catalyst is oxidized. An example of a first threshold value of the present invention corresponds to the temperature T ₁ of the present embodiment.

In step 5 (S5), when the time from the start-up reaches t _4, the control unit 15 operates the air supply unit 5, supplies air to the CO remover 3. As the time t _4, for example, can be set to 2 to 3 hours, the temperature of the reformer 1 and the transformer 2 is set to a later time than the time t ₃ when reaching a predetermined temperature.

  Next, in step 4 (S4), after the supply of air and the CO concentration is sufficiently reduced, the CO remover 3 outlet gas is switched to the polymer electrolyte fuel cell 7 side, and power generation is started.

As described above, when reaching a temperature thresholds T ₁ is a timing earlier than the time t _a, there is a high possibility that the oxidation catalyst is oxidized, as with the air supply timing in a normal start t ₃ hours If air is introduced later, the oxidation reaction heat of the hydrogen-containing gas may cause the catalyst temperature to rise and the resulting thermal runaway due to methanation, which may cause oxidation catalyst sintering or control the catalyst temperature. is there.

However, as in the present embodiment, the introduction of air is delayed by (t ₄ -t ₃ ) time from the timing of starting air supply in normal startup, and the reduction reaction of the oxidation catalyst that has been oxidized and deteriorated by the hydrogen-containing gas is completed. By introducing air after waiting, even if the oxidation catalyst is oxidized, it is possible to start stably.

In the present embodiment, T ₁ is set to a temperature suitable for the oxidation reaction. However, the temperature is not limited to this value, and normal startup operation (solid line) is not limited to this value until air introduction (t ₃ ) as shown in FIG. And the temperature at which the oxidation catalyst reaches the catalyst temperature in the start-up operation (dashed line) after the oxidation deterioration (for example, T ₁ ′ shown in FIG. 2).

Further, in this embodiment, in step 2 (S2), but the time the catalyst temperature of the oxidation catalyst becomes above T ₁ is determined whether at least t _a, for example, the catalyst in the time t _a temperature may be determined whether it is above T _1. In this case, when the catalyst temperature is above T ₁ of at time t _a, control is performed in step (S5) shown in FIG. 3, in the case of less than T ₁ is controlled in Step 3 (S3) is performed. In this case, an example of the specific timing of the present invention, is the time t _a.

In the present embodiment, the time t ₃ is a fixed time. However, a sensor for detecting the temperature of the reformer 1 is provided to monitor the temperature of the reformer 1, and the detected temperature reaches a predetermined temperature. the amount of time may be as t _3. A flow chart in this case is shown in FIG.

As shown in FIG. 4, if the time the catalyst temperature becomes T ₁ is not less than t _a in step 2, if the temperature of the reformer 1 is equal to or higher than a predetermined temperature at step 11, the process proceeds to step 12 Air supply is performed. On the other hand, if the time the catalyst temperature is T ₁ in step 2 is less than t _a, the air along with the reformer 1 becomes equal to or higher than the predetermined temperature at step 13, the elapsed time t ₄ when waiting further predetermined time in step 14 Supply is made. During this waiting time, the temperature increase associated with the reduction reaction of the oxidation catalyst that has been oxidized and degraded by the hydrogen-containing gas is completed. A stable start-up operation can be performed without running away.

(Embodiment 2)
The fuel cell system according to the second embodiment of the present invention will be described below.

  The basic configuration of the fuel cell system of Embodiment 2 is the same as that of Embodiment 1, but the control flow is different. Therefore, this difference will be mainly described. In addition, the same code | symbol is used about the step and structure same as Embodiment 1. FIG.

  FIG. 5 is a graph showing a temperature behavior of the oxidation catalyst of the fuel cell system according to the second embodiment. In FIG. 5, the graph of the catalyst temperature behavior in the normal startup operation is shown by a solid line, and the graph of the catalyst temperature behavior in the startup operation after the oxidation catalyst has deteriorated during a long-term stop is shown by a one-dot chain line. Has been. FIG. 6 is a control flowchart of the fuel cell system according to the second embodiment.

  First, the start-up operation of the fuel cell system of the present embodiment when the oxidation catalyst has not been oxidized and deteriorated before the start-up operation will be described.

In the fuel cell system of the second embodiment, the CO remover 3 is heated in step 1 as in the first embodiment. Next, the catalyst temperature of the CO remover 3 it is determined whether or not reached T ₂ or more is performed at a specific timing t ₅ of before the start of activation after t ₃ hours. Specifically, the catalyst temperature at the beginning of starting after _{t 5} in step 21 (S21) it is determined whether or not _{T 2} or more, when it is less than _{T 2} are, the process proceeds to step 22 (S22). The value of this T ₂ are, the oxidation catalyst is set to a temperature higher than the temperature range to be detected in the normal start-up operation that is not oxidized and deteriorated (from start-up time t _5).

Therefore, in the normal start-up operation, when it is confirmed that the catalyst temperature does not become higher than T ₂ at time t ₅ after the start of start and t _{3 has} elapsed from the start-up time in step S22, the process proceeds to step 23, and the control unit 15 operates the air supply unit 5 to supply air to the CO remover 3.

  Next, in step 4 (S4), after the supply of air and the CO concentration is sufficiently reduced, the CO remover 3 outlet gas is switched to the polymer electrolyte fuel cell 7 side, and power generation is started.

  Next, the start-up operation of the fuel cell system of the present embodiment after the oxidation catalyst is oxidized and deteriorated during the long-term stop period will be described.

The oxidation catalyst if the deteriorated oxide at time t ₅ is a specific timing until the time t ₃ as shown in FIG. 5, has reached the temperature threshold value T ₂ or more, the step from the step 21 24 proceeds to (S24), after _{t 4} hours from the start of activation, the control unit 15 supplies air to the CO remover 3 by operating the air supply unit 5. Here, when the hydrogen-containing gas is introduced when the oxidation catalyst is oxidized, the catalyst becomes hotter than during normal startup due to the reduction reaction of ruthenium oxide. Therefore, if it becomes higher temperature T ₂ than the temperature range to be detected in the normal starting operation it can be determined that there is a high possibility that the oxidation catalyst is oxidized. Incidentally, an example of the air starting the normal startup of the oxidizing gas of the present invention corresponds to a time t ₃ after the start start of this embodiment, the specific timing of the present invention, the time t ₅ after the start of activation corresponds to an example of the second threshold value of the present invention corresponds to T ₂ of the present embodiment.

  Subsequently, in step 4 (S4), after the air supply, after the CO concentration is sufficiently reduced, the control unit 15 switches the switching valve so that the CO remover 3 outlet gas flows to the polymer electrolyte fuel cell 7 side, Power generation is started.

As described above, in the fuel cell system of this embodiment, the temperature higher than the temperature range to be detected in normal starting operation at a specific timing t ₅ earlier than normal air supply is started at the time of startup When the catalyst temperature has reached, there is a high possibility that the oxidation catalyst has been oxidized. Therefore, the time is delayed by (t ₄ −t ₃ ) from time t ₃ which is a predetermined air supply timing. Since it is assumed that the reduction reaction of the oxidation catalyst that has deteriorated due to the hydrogen-containing gas will be completed during this delay, the oxidation catalyst will be stable without thermal runaway due to the methanation reaction even if air is supplied to the oxidation catalyst. Can be started.

(Embodiment 3)
The fuel cell system according to Embodiment 3 of the present invention will be described below.

The fuel cell system of the third embodiment, although the embodiment 2 the basic configuration of the embodiment is the same, the control flow when the catalyst temperature reaches T ₂ are different. Therefore, this difference will be mainly described. In addition, the same code | symbol is used about the step and structure same as Embodiment 2. FIG.

  FIG. 7 is a graph showing a temperature behavior of the oxidation catalyst of the fuel cell system according to the third embodiment. In FIG. 7, the graph of the catalyst temperature behavior in the normal startup operation is shown by a solid line, and the graph of the catalyst temperature behavior in the startup operation after the oxidation catalyst is oxidatively deteriorated during a long-term stop is shown by a dashed line. It is shown. FIG. 8 is a control flow diagram of the fuel cell system according to the third embodiment.

As shown in FIG. 8, in step 21 and step 22, it is determined that the catalyst temperature of the CO remover 3 has reached a value equal to or higher than T _{2 at} a specific timing t ₅ until t ₃ hours after starting. If YES, go to step 31.

In step 31 (S31) and Step 32 (S32), the catalyst temperature is determined whether it is _{T 3} below are performed during the period from the start-up time _{t 12} (not shown). When the catalyst temperature becomes equal to or lower than T ₃ , the control unit 15 operates the air supply unit 5 to supply air to the CO remover 3. Time the catalyst temperature becomes T ₃ below is indicated by t ₆ in FIG. For example, T ₃ can be set to 120 ° C., and t ₁₂ can be set to 6 hours, for example.

On the other hand, the catalyst temperature even after the time t ₁₂ (not shown) to be lowered to T _3, the hydrogen generating apparatus 11 determines that the fault is stopped (S33). Incidentally, an example of a third threshold value of the present invention corresponds to T ₃ of the present embodiment.

As described above, the fuel cell system according to the present embodiment is provided with the temperature threshold T ₂ as in the second embodiment, and the catalyst at the specific timing t ₅ before the normal air supply is started at the time of startup. If the temperature reaches T ₂ or more, delaying the air introduction. Then, in Embodiment 3, the end is heat generated by the reduction reaction of the oxidation degradation oxidation catalyst, the catalyst temperature is waiting for the fall in the T ₃ are introduced the air. For this reason, air is supplied to the oxidation catalyst at the timing when it is assumed that the reduction reaction of the oxidation catalyst is completed, so even if the oxidation catalyst is started in a state of oxidative degradation, the oxidation catalyst will run out of heat due to the methanation reaction. It becomes possible to start stably without doing.

(Embodiment 4)
The fuel cell system according to Embodiment 4 of the present invention will be described below.

  The basic configuration of the fuel cell system of Embodiment 4 is the same as that of Embodiment 3, but the control flow after air supply in Step 23 is different. Therefore, this difference will be mainly described. In addition, the same code | symbol is used about the step and structure same as Embodiment 3. FIG.

  FIG. 9 is a graph showing a temperature behavior of the oxidation catalyst of the fuel cell system according to the fourth embodiment. In FIG. 9, the graph of the catalyst temperature behavior in the normal startup operation is indicated by a solid line, and the graph of the catalyst temperature behavior in the startup operation after the oxidation catalyst is oxidatively deteriorated during a long-term stop is indicated by a dashed line. It is shown. FIG. 10 is a control flowchart of the fuel cell system according to the fourth embodiment.

In the fuel cell system of the fourth embodiment, after the air supply is performed in step 23, when the catalyst temperature rises to T _4, the air supply device 5 is stopped by the control unit 15. As the _{T 4,} for example, it can be set to 200 ° C.. Also, the time to stop the air supply is shown as a time t ₇ in FIG. Incidentally, an example of a fourth threshold value of the present invention corresponds to T ₄ of the present embodiment.

Meanwhile, after the air supply is performed, when the catalyst temperature until the CO concentration is sufficiently reduced is not a T ₄ is, CO remover 3 exit gas is switched to the polymer electrolyte fuel cell 7 side Power generation is started. The time until the CO concentration is sufficiently reduced may be after a certain time has elapsed from the air supply in step 23, or the time when the sensor for measuring the concentration of carbon monoxide is provided to detect the reduction of the CO concentration. It is also good.

As described above, the fuel cell system of the fourth embodiment, similarly provided the temperature threshold value T ₂ and the third embodiment, a normal specific timing t ₅ before the air supply is started at the time of startup when the catalyst temperature reaches T ₂ or higher, delay the air introduction end is heated by a hydrogen-containing gas by a reduction reaction of the oxidation catalyst, waiting for the catalyst temperature drops to introduce air. In Embodiment 4, since the reduction reaction of the oxidation catalyst until the start of air supply is insufficient, the temperature of the catalyst rises due to the heat generated by the reduction reaction of the oxidation catalyst and the heat generated by the oxidation reaction after the air supply. When the threshold value T4 of ₄ or more is reached, there is a possibility of thermal runaway, so the air supply is stopped. Therefore, the rapid increase in the temperature of the oxidation catalyst can be more reliably suppressed in the starting operation after the oxidation catalyst is oxidized and deteriorated, and a stable starting operation can be executed.

(Embodiment 5)
The fuel cell system according to Embodiment 5 of the present invention will be described below.

  The basic configuration of the fuel cell system of the fifth embodiment is the same as that of the fourth embodiment, but the control flow after the air supply stop in step 42 is different. Therefore, this difference will be mainly described. In addition, the same code | symbol is used about the same step and structure as Embodiment 4. FIG.

  FIG. 11 is a graph showing a temperature behavior of the oxidation catalyst of the fuel cell system according to the fourth embodiment. In FIG. 11, the graph of the catalyst temperature behavior in the normal startup operation is shown by a solid line, and the graph of the catalyst temperature behavior in the startup operation after the oxidation catalyst is oxidatively deteriorated during a long-term stop is shown by a one-dot chain line. It is shown. FIG. 12 is a control flowchart of the fuel cell system according to the fourth embodiment.

In the fuel cell system of the fifth embodiment, after the air supply is stopped as described in the fourth embodiment (S42), the catalyst temperature is to wait until the T ₅ below, at a T ₅ or less, the process proceeds to step 23, Air supply is started again from the air supplier 5. Time This again air supply is started is shown in Figure 11 as t _8. Incidentally, the fifth example of the threshold of the present invention corresponds to T ₅ of the present embodiment.

In the fuel cell system of the fifth embodiment, once supplying air to the oxidation catalyst, after stopping the supply of air before the oxidation catalyst is thermally runaway, to stop the air supply until the catalyst temperature becomes T ₅ below , without the risk of oxidation catalyst is thermally runaway, after stopping the air supply, it is highly likely that the reduction reaction of the oxidation catalyst is completed until the catalyst temperature becomes T ₅ below, if thereafter again supply air In addition, the rapid increase in the catalyst temperature can be suppressed more reliably, and the fuel cell can be shifted to the power generation operation in a stable state.

  Hereinafter, the behavior after oxidation of the oxidation catalyst of the fuel cell system of the present invention will be described more specifically based on examples.

(Example 1)
A 3 mm diameter Ru / γ-Al ₂ O ₃ catalyst is packed into a microreactor, and a gas with a dew point of 64 ° C. is produced using a cylinder of 0.5% CO-20% CO ₂ / H ₂ at a catalyst temperature of 150 ° C. Air was supplied and reacted so that [O ₂ ] / [CO] = 2. And SV4200h ^-1, the catalyst temperature of the point of 4mm from the catalyst upstream was measured with a thermocouple. After the reaction, the supply of hydrogen-containing gas and water was stopped, and the mixture was cooled to room temperature while supplying air. This test was repeated 60 times, and then a starting operation was performed.

In the start-up operation, the catalyst charged in the microreactor is purged with city gas 13A, the electric furnace temperature is increased to 130 ° C., and 0.5% CO-20% CO ₂ / H ₂ (reformed simulated gas) Then, water having a dew point of 64 ° C. was supplied.

  As a result, the catalyst temperature was 137 ° C. and the methane concentration was 620 ppm (see C in Table 1 below).

  Furthermore, when air is supplied after 30 minutes, it can be seen that in the oxidized catalyst, the catalyst temperature rises to 185 ° C., the methane concentration also increases to 6000 ppm, and the methanation is promoted as the catalyst temperature rapidly rises. (See D in Table 1 below).

(Comparative Example 1)
Without stopping the supply of air 60 times, the 3 mm diameter Ru / γ-Al ₂ O ₃ catalyst packed in the microreactor was purged with city gas 13A, the electric furnace temperature was raised to 130 ° C., 0.5% CO-20% CO ₂ / H ₂ and water with a dew point of 64 ° C. were supplied. The catalyst in a state where the supply of air has not been stopped 60 times is referred to as a Fresh state.

In this Fresh state, at the electric furnace temperature of 130 ° C., 30 minutes after switching to the reforming simulation gas (0.5% CO-20% CO ₂ / H ₂ ), the catalyst temperature is 130 ° C. and the methane concentration is The result was 510 ppm (see A in Table 1 below).

  Furthermore, when air was supplied after 30 minutes, in the case of Fresh, the catalyst temperature was 179 ° C. and the methane concentration was 2570 ppm (see B in Table 1 below).

（表１）の結果から、６０回の空気の供給停止を行って、触媒を酸化した場合に、起動動作を行い、空気を供給すると、メタン化反応が起こり触媒温度の急激な上昇が起こりやすくなっていることがわかる。

From the result of (Table 1), when the air supply is stopped 60 times and the catalyst is oxidized, the start-up operation is performed, and when air is supplied, the methanation reaction occurs and the catalyst temperature is likely to rise rapidly. You can see that

(Example 2)
In the same manner as in Example 1, the oxidized catalyst was activated by 60 times of air supply. 30 minutes after switching to the reformed simulation gas, the catalyst temperature was 136 ° C. and the methane concentration was 590 ppm (see E in Table 2 below).

  When the flow of the reforming simulation gas was continued for one day under these conditions, the catalyst temperature was 131 ° C., the methane concentration was reduced to 510 ppm, Ru was reduced, and heat generation was reduced (see F in Table 2 below). ).

After that, when air is supplied at [O ₂ ] / [CO] = 2, the catalyst temperature is 180 ° C., the methane concentration becomes 3100 ppm, and it can be seen that the catalyst temperature returns to a state where it is difficult for the catalyst temperature to rapidly increase due to the reduction. (See G in Table 2 below).

（実施例３）
実施例１と同様に、６０回の空気供給により酸化させた触媒の起動を行った。起動は、１３Ａパージを行い、電気炉温度を１４０℃まで上昇させ、改質模擬ガスに切り替えてから、３０分後に空気を[Ｏ_２]／ [ＣＯ]＝２で供給した。

(Example 3)
In the same manner as in Example 1, the oxidized catalyst was activated by 60 times of air supply. In the start-up, 13A purge was performed, the electric furnace temperature was raised to 140 ° C., and after switching to the reformed simulation gas, air was supplied at [O ₂ ] / [CO] = 2 after 30 minutes.

  Then, the catalyst temperature rose rapidly to 210 ° C. At this time, the supply of air was stopped, the catalyst temperature was cooled to 142 ° C., and then air was supplied again. As a result, the catalyst temperature increased only to 190 ° C. This control corresponds to an example of the control flow described in the fifth embodiment.

  Even if the oxidation catalyst rises to a temperature at which it is likely to run out of heat after the start of air supply, as shown in this example, if the air supply is temporarily stopped and the air is supplied again after the temperature has dropped, the catalyst temperature will rapidly increase. I found it difficult to rise.

  In the hydrogen generator of the present invention, although the oxidation catalyst of the CO remover has deteriorated, no abnormality related to the oxidation deterioration of the oxidation catalyst has been detected as the device until the start-up operation is started. Even if it is a case, it is possible to start stably, and it is useful as a fuel cell system and its operation method.

1 is a schematic diagram of a fuel cell system according to a first embodiment of the present invention. The figure which shows the graph of the temperature temporal change at the time of starting of the oxidation catalyst in the fuel cell system of Embodiment 1 concerning this invention. FIG. 3 is a control flow chart at the time of starting the fuel cell system according to the first embodiment of the present invention. Control flow chart at start-up of a modification of the fuel cell system according to Embodiment 1 of the present invention The figure which shows the graph of the temperature temporal change at the time of starting of the oxidation catalyst in the fuel cell system of Embodiment 2 concerning this invention. Control flow chart at the time of starting the fuel cell system according to the second embodiment of the present invention The figure which shows the graph of the temperature temporal change at the time of starting of the oxidation catalyst in the fuel cell system of Embodiment 3 concerning this invention. FIG. 7 is a control flow chart at the time of starting the fuel cell system according to the third embodiment of the present invention. The figure which shows the graph of the temperature aging change at the time of starting of the oxidation catalyst in the fuel cell system of Embodiment 4 concerning this invention. FIG. 7 is a control flow chart at the time of starting the fuel cell system according to the fourth embodiment of the present invention. The figure which shows the graph of the temperature temporal change at the time of starting of the oxidation catalyst in the fuel cell system of Embodiment 5 concerning this invention. FIG. 7 is a control flow chart at the time of starting the fuel cell system according to the fifth embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Reformer 2 Transformer 3 CO remover 4 1st heating unit 5 Air supply device 6 2nd temperature detector 7 Polymer electrolyte fuel cell (PEFC)
8 Second heating unit 9 Third temperature detector 10 Anode off-gas path 11 Hydrogen generator 12 Burner 13 Bypass path 14 Switching valve 15 Control unit 16 First temperature detector

Claims (8)

A reformer for generating a hydrogen-containing gas by a reforming reaction of the raw material;
A CO remover for reducing carbon monoxide in the hydrogen-containing gas delivered from the reformer by an oxidation reaction;
An oxidizing gas supply for supplying an oxidizing gas to the CO remover;
A temperature detector for detecting the temperature of the CO remover;
With a controller,
The controller is characterized in that at the time of startup, if the temperature detected by the temperature detector is higher than the temperature at the time of normal startup, the controller starts delaying the supply of the oxidizing gas from the oxidizing gas supplier from that at the time of normal startup. Hydrogen generator.   When the time when the temperature detected by the temperature detector is equal to or higher than the first threshold is earlier than normal at the time of startup, the controller starts supplying the oxidizing gas from the oxidizing gas supplier than at the time of normal startup. The hydrogen generator according to claim 1, wherein the hydrogen generator is delayed.   The controller delays the start of the supply of the oxidizing gas from the oxidizing gas supply device at the time of startup when the temperature detected by the temperature detector becomes equal to or higher than the second threshold value at a specific timing. The hydrogen generator according to claim 1.   4. The hydrogen generator according to claim 2, wherein the controller starts supplying the oxidizing gas from the oxidizing gas supply device when the temperature detected by the temperature detector decreases to be equal to or lower than a third threshold value. 5. .   The controller starts supplying the oxidizing gas from the oxidizing gas supplier, and then the oxidizing gas is detected when a temperature detected by the temperature detector becomes equal to or higher than a fourth threshold value that is larger than the third threshold value. The hydrogen generator according to claim 4, wherein the supply of the oxidizing gas from the supplier is stopped.   The controller stops supplying the oxidizing gas from the oxidizing gas supplier, and then supplies the oxidizing gas when the temperature detected by the temperature detector becomes equal to or lower than a fifth threshold value that is smaller than the fourth threshold value. The hydrogen generator according to claim 5, wherein the supply of the oxidizing gas from the vessel is resumed. A hydrogen generator according to any one of claims 1 to 6;
A fuel cell system comprising: a fuel cell that generates electricity using a hydrogen-containing gas supplied from the hydrogen generator. A reformer for generating a hydrogen-containing gas by a reforming reaction of the raw material; a CO remover for reducing carbon monoxide in the hydrogen-containing gas delivered from the reformer by an oxidation reaction; and the CO An operating method of a hydrogen generator comprising an oxidizing gas supplier for supplying oxidizing gas to a remover and a temperature detector for detecting the temperature of the CO remover,
At the time of startup, when the temperature detected by the temperature detector is higher than the temperature at the time of normal startup, control is performed so that the start of supply of the oxidizing gas from the oxidizing gas supplier is delayed from that at the time of normal startup. Operation method of hydrogen generator.

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