JP2008243592A - Fuel cell device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell device capable of easily controlling an igniting heater, and high in ignition reliability. <P>SOLUTION: This fuel cell device is provided with: a storage vessel 1; solid oxide fuel cells 4a stored in the storage vessel 1; a reformer 3 reforming raw fuel to supply fuel gases to the solid oxide fuel cells 4a; an igniting heater 15 stored in the storage vessel 1; and a control part 11 controlling electricity application to the igniting heater 15 wherein the control part 10 applies electricity to the igniting heater 15 during a starting process to ignite and burn a mixture gas comprising surplus fuel gases supplied to fuel electrodes of the fuel cells 4a without having been used for a power generation reaction, and surplus oxygen-containing gases supplied to oxygen electrodes of the fuel cells 4a without having been used for the power generation reaction. The control part 10 continuously applies electricity to the igniting heater 15 during the starting process. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel cell device, which contains a solid oxide fuel cell and an ignition heater in a storage container, energizes the ignition heater during startup, is supplied to the fuel electrode of the fuel cell, and is used for a power generation reaction. The present invention relates to a fuel cell device that ignites and burns a mixed gas of a surplus fuel gas that has not existed and a surplus oxygen-containing gas that has been supplied to the oxygen electrode of the fuel cell and has not been used in a power generation reaction.

  In recent years, fuel cells of solid polymer type, phosphoric acid type, molten carbonate type and solid oxide type have been proposed as next-generation energy. In particular, solid oxide fuel cells have advantages such as high operating temperature, high power generation efficiency, and use of exhaust heat, and research and development are being promoted.

Conventionally, as a method for operating a solid oxide fuel cell, when partial oxidation reforming is performed by a reformer or steam reforming during a start-up process, the ignition heater is energized at each time to Ignition and combustion of a mixed gas of surplus fuel gas supplied to the fuel electrode of the battery and not used for the power generation reaction and surplus oxygen-containing gas supplied to the oxygen electrode of the fuel cell and not used for the power generation reaction (See Patent Document 1).
JP 2006-86016 A

  When performing partial oxidation reforming with a reformer, when performing steam reforming, the gas quality and amount of gas supplied from the reformer to the fuel cell change, so an ignition heater is used for partial oxidation reforming. In order to improve ignition reliability, it is desirable to energize and ignite the ignition heater again when steam reforming, even if energization is performed and ignition is stopped.

  However, every time the gas quality or amount of gas supplied from the reformer to the fuel cell changes, controlling the energization to the ignition heater has a problem that the control becomes complicated.

  An object of the present invention is to provide a fuel cell device that can easily control an ignition heater and has high ignition reliability.

  The fuel cell device of the present invention includes a storage container, a solid oxide fuel cell stored in the storage container, and reforming for reforming raw fuel to supply fuel gas to the solid oxide fuel cell. And an ignition heater accommodated in the storage container, and a control unit for controlling energization to the ignition heater, the control unit energizing the ignition heater during the starting process. Igniting a mixed gas of surplus fuel gas supplied to the fuel electrode of the fuel cell and not used for power generation reaction and surplus oxygen-containing gas supplied to the oxygen electrode of the fuel cell and not used for power generation reaction In the fuel cell apparatus, the controller continuously energizes the ignition heater during the start-up process.

  In such a fuel cell device, since the ignition heater is energized continuously during the start-up process, the ignition reliability during the start-up process can be improved with simple control.

  In the fuel cell device of the present invention, the reformer is stored in the storage container, and the reformer is heated by combustion gas. In such a fuel cell device, the reformer is heated with the combustion gas and the raw fuel is reformed. As described above, the ignition gas is generated in order to improve the ignition reliability of the surplus gas. Can be easily controlled, heating control of the reformer is facilitated, and control of the reforming reaction in the reformer is facilitated.

  Furthermore, the fuel cell device of the present invention is characterized in that partial oxidation reforming and steam reforming of the raw fuel are performed in the reformer during the startup process. The partial oxidation reforming of the raw fuel is performed, for example, by supplying a predetermined amount of air and raw fuel to the reformer, and the steam reforming is performed, for example, by supplying a predetermined amount of water and raw fuel to the reformer. Since the gas type and gas amount used in each reforming are different, for example, even if it is ignited once by an ignition heater at the time of partial oxidation reforming, there is a risk of misfire at the time of steam reforming However, in the present invention, since the ignition heater is energized continuously during the start-up process, even if the gas type and gas amount change and misfire occurs, the ignition is immediately re-ignited and the ignition reliability can be improved.

  Further, the fuel cell device of the present invention is characterized in that the controller stops energization to the ignition heater after elapse of a certain time after the steam reforming is started during the starting process. Since steam reforming has the best reforming characteristics, steam reforming is usually performed during steady operation of the fuel cell after the start-up process is completed. The amount of gas does not change much and there is almost no misfire. Therefore, after steam reforming is started during the start-up process, power is not supplied to the ignition heater by stopping energization to the ignition heater after a predetermined time has elapsed.

  The ignition heater used in the present invention is preferably a ceramic heater. The ceramic heater becomes a high temperature of about 1000 ° C and functions well as an ignition source. Moreover, since there is no noise that has become a problem with conventional spark plugs, there is no effect on peripheral equipment and fuel. It can be suitably used as a battery ignition source. In addition, after ignition, the ceramic heater is exposed to a high-temperature combustion gas atmosphere. However, since the ceramic heater has excellent corrosion resistance even in a high-temperature atmosphere, even if it is exposed to a high-temperature combustion gas for a long time, material deterioration will occur. There is almost no longer life, resulting in longer life of the fuel cell itself.

  In the fuel cell device of the present invention, since the ignition heater is energized continuously during the startup process, the ignition reliability during the startup process can be improved with simple control.

  Hereinafter, an embodiment of the fuel cell device of the present invention will be described. FIG. 1 is a schematic configuration diagram showing an outline of a fuel cell device.

  As shown in FIG. 1, the fuel cell device is configured such that a reformer 3 and a cell stack 4 are accommodated in a storage container 1. The cell stack 4 is configured by standing a plurality of solid oxide fuel cell (fuel cell) 4a on a gas manifold 4b.

  The reformer 3 of the storage container 1 can be supplied with raw fuel such as city gas and propane gas from the outside by the gas pump 2, can be supplied with water by the water pump 7, and is further supplied by the air pump 9. In addition, an oxygen-containing gas such as air can be supplied.

  The reformer 3 is capable of partial oxidation reforming and steam reforming using raw fuel, water, and oxygen-containing gas, and the fuel gas reformed by the reformer 3 is supplied to the fuel cell 4a of the cell stack 4. It is configured to be supplied. The gas pump 2, the water pump 7, and the air pump 9 can be controlled by the control unit 10. The broken line in FIG. 1 indicates a main signal from the control device 10 or a main signal to the control unit 10.

  In addition, air (oxygen-containing gas) for power generation is supplied into the storage container 1 through the air introduction pipe 13 by the air blower 11.

  That is, the fuel cell 4a has a gas passage through which the fuel gas flows. The fuel gas flows from the manifold 4b through the gas passage of the fuel cell 4a and is used for the power generation reaction. The fuel gas is discharged above the fuel battery cell 4a (combustion region F) through the gas passage. On the other hand, air is supplied into the storage container 1 from the air introduction pipe 13 by the air blower 11, and the air that has not been used for the power generation reaction is directed upward of the fuel cell 4a.

  And in this form, the surplus fuel gas (it may be raw fuel) discharged | emitted above the fuel cell 4a (combustion area | region F) is made into the fuel gas for combustion.

  That is, in this embodiment, the combustion region F in which surplus fuel gas discharged above the cell stack 4 burns, in other words, the ignition heater 15 as ignition means, the combustion state of the fuel gas, above the cell stack 4. Is provided above the combustion region F, and the reformer 3 is heated by the combustion of the fuel gas discharged from the cell stack 4. It is configured. The heat generated by the ignition heater 15 is used as an ignition source for combustion, and the ceramic heater 15 for ignition becomes a high temperature of about 1000 ° C. and functions sufficiently as an ignition source.

  As the temperature sensor 17, a K-type thermocouple that can measure a temperature of 1000 ° C. or higher and that is fast in response and inexpensive can be used. Further, the temperature sensor 17 is arranged so as not to detect the radiant heat from the ignition heater 15 as much as possible. Therefore, the fuel gas blown out from the cell stack 4 is ignited by the ignition heater 15, the fuel gas is combusted, the temperature of the reformer 3 is increased, and the raw fuel is reformed. The combusted exhaust gas is discharged from the exhaust pipe 19 to the outside of the storage container 1. A signal from the temperature sensor 17 is sent to the control unit 10, and energization of the ignition heater 15 can be controlled by the control unit 10.

  The ignition heater 15 is preferably a ceramic heater from the viewpoint of durability. For example, a heating element made of W, Mo or the like is covered with a ceramic such as alumina, silicon carbide, or silicon nitride.

  A method for starting the fuel cell device configured as described above will be described with reference to FIG. First, in S <b> 1, the air blower 11 is activated to supply air into the storage container 1. Here, at the time of ignition operation, if the supply amount by the air blower 11 is large, the flame may be blown out. Therefore, the flow rate is set small (for example, 40 L / min). Since the air supply by the air blower 11 reaches the combustion region F above the fuel battery cell 4a and there is a risk of blowing out the flame of the fuel battery cell 4a, the air supply amount by the air blower 11 is reduced, so that the combustion region The amount of air supplied to F can be reduced. Thereafter, in S2, the ignition heater 15 is energized to preheat the ignition heater 7.

  Thereafter, the gas pump 2 is driven in S3 to supply raw fuel into the reformer 3, and the air pump 9 is driven in S4 to supply air into the reformer. Partial oxidation reforming is performed in the reformer 3, and the reformed fuel gas passes through the gas passage of the fuel cell 4a via the manifold 4b, and surplus fuel gas that has not been used for the power generation reaction is removed. Released into the combustion region F. On the other hand, since the air supplied by the air blower 11 exists around the fuel cell 4a, the surplus fuel gas is ignited by the ignition heater 15 and burned in the combustion region F. When the temperature is detected by the temperature sensor 11, energization of the ignition heater 15 is started, and when the temperature becomes equal to or higher than a certain temperature, the controller 10 determines that the ignition has occurred.

  When the gas pump 2 is started in S3, the raw fuel passes through the reformer 3 without being reformed and is released above the fuel cell 4a, but is ignited and burned by the ignition heater 15. The reformer 3 is heated by the combustion gas, and then the air pump 9 is started in S4, and when the catalyst in the reformer 3 reaches a predetermined temperature, partial oxidation reforming is started. The refined fuel gas is supplied into the fuel cell 4a, and the fuel gas that has not been used for the power generation reaction is released from the cell tip and burned.

  Thereafter, it is determined in S5 whether autothermal reforming (ATR) is possible. Autothermal reforming is a combined operation of partial oxidation reforming and steam reforming, and if this is changed directly from partial oxidation reforming to steam reforming, the gas type and amount of gas change abruptly, preventing this. Therefore, it is a reforming method that uses both partial oxidation reforming and steam reforming, and whether or not autothermal reforming (ATR) is possible is, for example, whether the module temperature is 200 ° C. or higher and the temperature inside the reformer is When it is 650 ° C. or higher, it is determined to be possible. Partial oxidation reforming is an exothermic reaction, but steam reforming is an endothermic reaction, so if the temperature rises above a certain level so that the module temperature and reformer temperature can be maintained even after shifting to steam reforming. Judge that autothermal reforming (ATR) is possible.

  If it is determined that autothermal reforming (ATR) is possible, the water pump 7 is driven in S6 to supply water (to become water vapor) to the reformer 3, while the air supply amount by the air pump 9 The autothermal reforming (ATR) is performed in the reformer.

  Thereafter, it is determined whether or not steam reforming is possible in S7. Since steam reforming is an endothermic reaction, whether steam reforming is possible or not is determined as possible, for example, when the module temperature is 400 ° C. or higher and the temperature inside the reformer is 550 ° C. or higher. .

  If it is determined that steam reforming is possible, the drive of the air pump 9 is stopped in S8, and the air supply by the air pump 9 is stopped. On the other hand, the amount of water supplied by the water pump 7 is increased to perform steam reforming.

  Then, after the air pump 9 is stopped, energization to the ignition heater 15 is stopped after a lapse of a certain time. The fixed time is a temperature at which the module temperature is sufficiently high and spontaneous ignition occurs.

  In the fuel cell apparatus as described above, the control unit 10 energizes the ignition heater 15 during the start-up process, and is supplied to the fuel electrode of the fuel cell 4a, and excess fuel gas or raw fuel that has not been used for the power generation reaction. And the surplus oxygen-containing gas supplied to the oxygen electrode of the fuel battery cell 4a and not used in the power generation reaction is ignited and burned, but the controller 10 continues the ignition heater 15 during the start-up process. Therefore, the ignition reliability of the surplus fuel gas or the mixed gas of the raw fuel and the oxygen-containing gas during the start-up process can be improved with simple control.

  That is, the partial oxidation reforming of the raw fuel is performed, for example, by supplying a predetermined amount of air and raw fuel to the reformer 3, and the steam reforming is performed by, for example, water and raw fuel being placed in the reformer. Since the gas type and the amount of gas used in each reforming are different, the autothermal reforming (ATR) is performed even if the ignition heater is ignited once during partial oxidation reforming. ) Or in the steam reforming stage, but in the present invention, the ignition heater 15 is energized continuously during the start-up process. Reignition can improve ignition reliability. Further, since the ignition heater 15 is energized continuously during the start-up process, incomplete combustion does not occur and the CO concentration can be reduced.

  In addition, after the steam reforming is started during the start-up process, the control unit 10 energizes the ignition heater 15 after the module temperature becomes sufficiently high and reaches a temperature at which it spontaneously ignites (a certain time has elapsed). Since the operation is stopped, unnecessary power supply to the ignition heater 15 is not performed.

  Furthermore, since a ceramic heater is used as the ignition heater 15, it can be suitably used as an ignition source for a fuel cell. Even when exposed to a high-temperature combustion gas for a long time, there is almost no material deterioration, resulting in a long life. The life of the fuel cell itself is extended.

  The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to such embodiments, and various modifications and corrections can be made without departing from the scope of the present invention. It goes without saying that this is possible.

  For example, in the above embodiment, the fuel cell device provided with a specific reformer above the cell stack has been described, but the present invention can be applied even when the reformer is provided other than above the cell stack. . Furthermore, although the fuel cell apparatus which accommodated the reformer in the storage container was demonstrated in the said form, the reformer may be arrange | positioned on the outer side of the storage container.

  Moreover, although the case where air was supplied to the outer surface of the fuel cell 4a and the fuel gas was supplied to the inside was described in the above embodiment, the present invention is a case where air is supplied to the inside of the fuel cell and the fuel gas is supplied to the outside. Even applicable. In this case, it goes without saying that an air electrode is formed inside the fuel cell and a fuel electrode is formed outside.

It is sectional drawing which shows suitable embodiment of the fuel cell apparatus of this invention. It is a flowchart which shows the starting method of the fuel cell apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Storage container 2 ... Gas pump 3 ... Reformer 4 ... Cell stack 4a ... Fuel cell (fuel cell)
DESCRIPTION OF SYMBOLS 7 ... Water pump 9 ... Air blower 10 ... Control part 15 ... Ignition heater 17 ... Temperature sensor F ... Combustion area

Claims (4)

A storage container, a solid oxide fuel cell stored in the storage container, a reformer for reforming raw fuel to supply fuel gas to the solid oxide fuel cell, and the storage container The ignition heater is housed and a control unit that controls energization of the ignition heater, and the control unit energizes the ignition heater during the start-up process to the fuel electrode of the fuel cell. A fuel cell device that ignites and burns a mixed gas of surplus fuel gas that is supplied and not used for power generation reaction and surplus oxygen-containing gas that is supplied to the oxygen electrode of the fuel cell and is not used for power generation reaction The fuel cell device is characterized in that the controller continuously energizes the ignition heater during the starting process. 2. The fuel cell device according to claim 1, wherein the reformer is housed in the housing container, and the reformer is heated by combustion gas. 3. The fuel cell device according to claim 1, wherein partial oxidation reforming and steam reforming of the raw fuel are performed in the reformer during the starting process. The fuel according to any one of claims 1 to 3, wherein the control unit stops energization of the ignition heater after a predetermined time has elapsed after the steam reforming is started during the startup process. Battery device.

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