JP2008135268A - Starting method of fuel cell device - Google Patents

Abstract

A fuel cell operating method capable of making a determination in a short time without making an erroneous ignition determination.
A fuel cell comprising a fuel cell for generating electric power by supplying a fuel gas and an oxygen-containing gas, an ignition heater for igniting a combustion fuel gas, and a temperature sensor for detecting the temperature of a combustion region. In this battery device starting method, after the ignition operation of the combustion fuel gas by the heater 7 is performed, within a predetermined ignition determination time t ₀ , the temperature T ₀ ° C of the combustion region F before ignition is set to the predetermined temperature T. If the temperature rises by ₁ ° C. or more, it is determined that ignition has occurred, and if ignition cannot be determined within the ignition determination time t _0, it is determined that no ignition has occurred, and the startup process is continued.
[Selection] Figure 2

Description

  The present invention provides a fuel cell comprising a fuel cell that is supplied with fuel gas and an oxygen-containing gas to generate power, ignition means for igniting the combustion fuel gas, and a temperature sensor for detecting the temperature of the combustion region of the combustion fuel gas. The present invention relates to a method for starting a battery device.

  Conventionally, in a fuel cell device, fuel gas is combusted to raise the temperature of the reformer, and the combustion state at the time of ignition is detected by a flame using a photosensor (Cds) or by a temperature sensor such as a thermocouple. Confirmed by detection. As a device using a temperature sensor, for example, as in Patent Document 1, in a reformer used in a polymer electrolyte fuel cell, after supplying a fuel gas for combustion, an ignition means such as an ignition transformer is used to perform an ignition operation. The temperature of the combustion region is detected by a temperature sensor, and it is determined that ignition has occurred when the detected temperature is equal to or higher than an ignition determination temperature that is a predetermined absolute temperature.

Also, a solid oxide fuel cell also has a known start-up method in which an ignition operation is performed using a heater and ignition is performed. Even in this case, whether or not ignition is possible is determined based on the absolute temperature of the temperature sensor (for example, Patent Document 2). reference).
JP 2004-116934 A JP 2006-86016 A

  In such a fuel cell apparatus, when the temperature of the combustion region is detected by the temperature sensor and the ignition determination is performed at the absolute temperature, there is a problem that the determination is erroneous or the determination takes time.

  That is, when the temperature of the combustion region is not cooled to room temperature, such as when restarting in a short time after shutdown, the temperature of the temperature sensor may already exceed the ignition determination temperature before the ignition operation. .

  For example, when the ignition determination temperature is designed at 100 ° C. and the temperature of the combustion region at the time of restart is 200 ° C., it is erroneously determined that the ignition has occurred even if the ignition is not performed.

  For example, when city gas is used as the combustion fuel gas, if the ignition determination temperature is 600 ° C., which is 536 ° C. or more, which is the spontaneous ignition temperature of the main component methane, the temperature of the combustion region is, for example, 100 ° C. If it is cooled to a certain level, it takes time until the temperature sensor is heated to 600 ° C. or higher even if it is normally ignited. Therefore, it is necessary to lengthen the determination time, and the combustion fuel gas at the time of non-ignition There was a problem that it was not possible to shut off the gas quickly, and the discharge of unburned gas to the outside took a long time.

  In particular, since the solid oxide fuel cell has a high operating temperature and operates at 600 to 1000 ° C., among the fuel gas supplied to the fuel cell, the excess fuel gas that has not been used for the power generation reaction is burned, Since the temperature is raised to the operating temperature by heating with a burner, there is a problem that it is easy to make a mistaken determination and it takes a long time to make the determination.

  An object of this invention is to provide the starting method of the fuel cell apparatus which can determine in a short time, without making an ignition determination mistake.

The method for starting a fuel cell device according to the present invention includes a fuel cell that is supplied with a fuel gas and an oxygen-containing gas to generate power, an ignition means that ignites the combustion fuel gas, and a temperature in the combustion region of the combustion fuel gas. A start method for a fuel cell device comprising: a temperature sensor that performs an ignition operation on the combustion fuel gas by the ignition means, and then performs the combustion before ignition within a predetermined ignition determination time t ₀ When the temperature rises from the temperature T ₀ ° C of the region to a predetermined temperature T ₁ ° C or higher, it is determined that ignition has occurred, and if it cannot be determined that ignition has not occurred within the ignition determination time t _0, it is determined that ignition has not occurred. A process is advanced according to the said determination of ignition.

In such a fuel cell device activation method, the ignition determination is performed based on the temperature rise T ₁ ° C before and after the ignition operation, not on the absolute temperature of the combustion region, so only when the fuel cell device is activated from a room temperature state. If the combustion zone temperature before startup is lower than the temperature of the combustion zone during steady operation by at least T ₁ ° C., the fuel cell device is not cooled to room temperature (the fuel cell device is hotter than room temperature). Even if it is activated, unignition can be reliably detected, and the ignition determination can be made in a short time.

  In addition, the fuel cell device activation method of the present invention is characterized in that the supply of the combustion fuel gas is stopped when it is determined that no ignition has occurred. In such an operation method, discharge of unburned gas to the outside can be suppressed.

Furthermore, in the method for starting the fuel cell device according to the present invention, the temperature of the combustion region is equal to or higher than the spontaneous ignition temperature of the combustion fuel gas within the ignition determination time t ₀ after performing the ignition operation by the ignition means. It is determined that ignition has occurred when the temperature reaches a set temperature T ₂ ° C or higher.

In such a fuel cell device start-up method, the temperature difference between the temperature of the combustion region before ignition and the temperature of the combustion region during steady operation is T _{1, for} example, when restarting immediately after stopping the operation of the fuel cell device. Although it may be lower than ° C., in the present invention, it is determined that the ignition has occurred when the combustion temperature of the combustion fuel gas is equal to or higher than T ₂ ° C. Therefore, accurate determination can be made. Further, after the stop of the operation of the fuel cell system, such as when performing an immediate reboot, as the temperature of the combustion region before ignition is increased, since the temperature difference between the temperature of the combustion region during steady operation is reduced, T ₁ of ℃ Although the temperature rise time tends to be long, in the present invention, the combustion region temperature before ignition is T ₂ −T in order to determine that the ignition has occurred when the combustion gas reaches or exceeds the spontaneous ignition temperature T ₂ ° C. until autoignition temperature T ₂ ° C. from ₁ ℃ is most because the determination time is prolonged, taking into account the time for the temperature rise from the T ₂ -T ₁ ℃ to T ₂ ° C., may be determined ignition determination time, needlessly Therefore, it is not necessary to lengthen the ignition determination time, whereby it is possible to quickly determine when the ignition fails and to reduce the emission of unburned gas.

  Further, in the start-up method of the fuel cell device of the present invention, when performing the ignition operation by the ignition means, the oxygen-containing gas supply amount to the combustion region is set low, and after determining that the ignition has been performed, the oxygen-containing gas supply amount It is characterized by increasing.

  If there is a large supply of oxygen-containing gas during ignition operation, the flame may be blown out, so the oxygen-containing gas supply amount should be set low during ignition operation. By increasing the supply amount, reliable ignition can be performed, and release of unburned gas when unignited can be suppressed.

  Further, the method for starting the fuel cell device according to the present invention determines that the ignition has not been performed, stops supplying the combustion fuel gas, repeats the ignition operation by the ignition means again, and repeats the ignition operation by the ignition means a predetermined number of times. If the ignition cannot be determined even after repeated, the ignition operation by the ignition means is stopped after the supply of the combustion fuel gas is stopped.

  This is because the combustion fuel gas piping is not filled with the combustion fuel gas when it is started for the first time after installation or when it has not been used for a long time. It takes a certain amount of time. However, since the fuel gas is immediately released to the combustion region when the fuel cell is restarted after being filled, unnecessarily increasing the determination time leads to a large amount of unburned gas being released. In the present invention, the ignition operation is repeated, and when the ignition operation cannot be determined even after repeating the ignition operation a predetermined number of times, the ignition operation is stopped, so that a large amount of unburned gas can be released. In particular, when it is determined that there is no ignition for each ignition operation, the release of the unburned gas can be further suppressed by stopping the supply of the combustion fuel gas.

  In addition, ignition failure has various factors such as changes in the moisture content of air due to the weather (air temperature and humidity), changes in the degree of moisture adsorption in the module, and scale adhesion to ignition means such as ignition heaters. This can alleviate the effects of disturbances other than equipment failure, prevent the equipment from shutting down immediately, and prevent the user from losing usability.

  Further, in the method for starting the fuel cell device of the present invention, when it is determined that the ignition has not been performed and the supply of the fuel gas for combustion is stopped, the ignition operation by the ignition means is performed again. The ignition operation is performed while reducing the gas supply amount.

  In such a start-up method of the fuel cell device, when it is determined that the ignition has not been performed, the ignition operation is performed by reducing the amount of oxygen-containing gas supplied to the combustion region compared to the previous ignition operation. In the case of blowing off, ignition can be ensured by reducing the supply amount of the oxygen-containing gas during the ignition operation.

Furthermore, the starting method of the fuel cell device according to the present invention is characterized in that the ignition means is a heater, and the heater is energized and preheated for a preheating time t ₁ before the supply of the combustion fuel gas is started. To do. In such a fuel cell device start-up method, the ignition time can be shortened compared with the case where the heater is ignited by starting the supply of the fuel gas for combustion, and the unburned gas is released to the outside accordingly. Less. In addition, if the heater surface temperature decreases due to deterioration of heater performance due to long-term use, scale adhesion to the heater, etc., ignition operation is performed with the heater preheated for a long time and sufficiently heated. By performing the above, it is possible to prevent a decrease in ignition performance.

Further, in the method for starting the fuel cell device of the present invention, when it is determined that the ignition has not been performed and the supply of the fuel gas for combustion is stopped, when the ignition operation is performed again by the ignition means, the heater preheating time t ₁ This is characterized in that the ignition operation is performed with a length longer than that in the previous ignition operation. In such a fuel cell device start-up method, the ignition time can be shortened compared with the case where the heater is ignited by starting the supply of the fuel gas for combustion, and the unburned gas is released to the outside accordingly. In addition, if the heater surface temperature decreases due to deterioration of the heater performance due to long-term use, scale adhesion to the heater, etc. The ignition reliability can be improved by performing the ignition operation with the temperature raised.

  Furthermore, the method for starting the fuel cell device according to the present invention is characterized in that when it is determined that no ignition has occurred, an abnormality is displayed on the display device. Thereby, it can confirm that the fuel gas for combustion is not ignited from the abnormality display of a display apparatus.

  In the method for starting the fuel cell device according to the present invention, the ignition determination for the combustion fuel gas is determined based on the temperature rise from before the ignition operation. Therefore, even when the fuel cell device is restarted, the ignition determination is ensured (accurate). ) Can be quickly performed, and release of unignited unburned gas can be suppressed.

  Hereinafter, an embodiment of the starting method 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 fuel cells (fuel cells) 4a on a gas manifold 4b. Raw gas such as city gas and propane gas is supplied from the outside to the reformer 3 of the storage container 1 by the gas pump 2, and the fuel gas reformed by the reformer 3 is the fuel cell of the cell stack 4. 4a. Further, air (oxygen-containing gas) is supplied into the storage container 1 through the air introduction pipe 6 by the air blower 5.

  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 from the air introduction pipe 6 into the storage container 1 by the air blower 5.

  And in this form, the surplus fuel gas discharge | released above the fuel cell 4a (combustion area | region F) is made into the fuel gas for combustion.

  In other words, in this embodiment, the combustion region F in which surplus fuel gas discharged above the cell stack 4 burns, in other words, the heater 7 as ignition means and the combustion state of the fuel gas are measured above the cell stack 4. The reformer 3 is provided above the combustion region F, and the reformer 3 is configured to be heated by the combustion of the fuel gas discharged from the cell stack 4. Has been.

  As the temperature sensor 8, 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 8 is arranged so as not to detect the radiant heat from the heater 7 as much as possible. Therefore, the fuel gas blown out from the cell stack 4 is ignited by the heater 7, the fuel gas is combusted, the reformer 3 is heated, and the raw fuel gas is reformed. The burned exhaust gas is discharged from the exhaust pipe 9 to the outside of the storage container 1.

  A method for starting the fuel cell device configured as described above will be described with reference to FIG. When activation of the fuel cell device is started, first, activation processing that is preparation for power generation is performed.

First, to set a preheating time _{t 1} of the ignition heater 7 to 1 minute at S1. In S2, the air blower 5 is activated to supply air into the storage container 1. Here, at the time of the ignition operation, if the supply amount by the air blower 5 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 5 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 5 is reduced, so that the combustion region The amount of air supplied to F can be reduced. Then, by energizing the heater 7 at S3, waits preheating time _{t 1} which is set in S4. Thereby, the heater 7 is preheated. At the time of restart, the fuel gas remaining in the storage container 1 during this waiting time is discharged by supplying air into the storage container 1.

When the preheating time t ₁ has elapsed, after storing the temperature detected by the temperature sensor 8 as temperature T ₀ before ignition in S5, activates the gas pump 2 in S6, the reformer 3 in the raw fuel gas of the container 1 The supplied and reformed fuel gas is supplied to the fuel cell 4a, and surplus fuel gas that has not been used for the power generation reaction is released to the combustion region F, and attempts to ignite this surplus fuel gas.

Then, in S7, it is confirmed whether the ignition determination time t ₀ (for example, 1 minute) has elapsed. If it has not elapsed, it is checked in S8 whether the detected temperature of the temperature sensor 8 has increased by T ₁ (for example, 100 ° C.) ° C. from T ₀ ° C. stored in S5. In other words, it is confirmed whether the detected temperature (absolute temperature) of the temperature sensor 8 is equal to or higher than [T ₀ + T ₁ ] ° C. If [T ₀ + T ₁ ] ° C. or higher, it is determined that ignition has occurred, and the process proceeds to S10. When the temperature is lower than [T ₀ + T ₁ ] ° C., it is confirmed in S9 whether the temperature detected by the temperature sensor 8 is equal to or higher than T ₂ ° C. Here T ₂ are the autoignition temperature above the predetermined temperature of the fuel gas. Here, city gas is used as the fuel gas, and since the spontaneous ignition temperature of methane, which is the main component thereof, is 536 ° C., the set temperature T ₂ equal to or higher than the spontaneous ignition temperature is set to 600 ° C.

If the detected temperature of the temperature sensor 8 is equal to or higher than T ₂ ° C., it is determined that ignition has occurred because of spontaneous ignition, and the process proceeds to S10. If it is less than T ₂ ° C, the determination is repeated from S7 again. Therefore, if the detected temperature of the temperature sensor 8 is equal to or higher than [T ₀ + T ₁ ] ° C. or higher than T ₂ ° C. within the ignition determination time t ₀ , it is determined that the ignition has occurred, and the process proceeds to S 10. 5 is increased to a flow rate (for example, 60 L / min) at which the air-fuel ratio becomes an optimum air-fuel ratio, and the operation shifts to a steady operation.

If the detected temperature of the temperature sensor 8 does not exceed [T ₀ + T ₁ ] ° C. or higher than T ₂ ° C. within the ignition determination time t ₀ , it is determined that no ignition has occurred, and in S11, the raw fuel gas is discharged. After the gas pump 2 is stopped and the supply of the fuel gas, which is a combustion fuel gas, to the combustion region F is stopped, it is confirmed in S12 whether or not it is within a predetermined number of retries (for example, 3 times). After extending the preheating time t ₁ of the heater 7 to 3 minutes in S13 if it is within the number of retries, the process returns to S2, and repeats the ignition operation again. If the ignition is not ignited even after repeating the predetermined number of retries (three times), the determination is NO in S12, the process proceeds to S14, an abnormal display is displayed on the display device, for example, the monitor screen, and the ignition operation is performed in S15. To stop.

In the starting method of the fuel cell device as described above, since the temperature rise (temperature difference) T ₁ ° C before and after the ignition operation is determined in S8, the fuel cell device is cooled to the room temperature after the fuel cell device is stopped. Even if starting is started (restarting) at a stage where there is no ignition, unignition can be detected reliably and quickly, and release of unburned gas can be suppressed. Further, when the temperature in the storage container 1 exceeds 600 ° C., for example, when the fuel cell apparatus is restarted immediately after the operation is stopped, it takes time to increase the temperature of T ₁ ° C. or the combustion region during steady operation When the temperature of F is lower than 700 ° C., T ₁ ° C. may not increase. However, when the temperature detected by the temperature sensor 8 is S ₂ (600) ° C. or higher in S9, the ignition temperature is higher than the spontaneous ignition temperature. Because it is automatically judged, it can respond to restart from high temperature.

  Further, during the ignition operation, the supply amount by the air blower 5 is reduced in S2 to improve the ignitability, and the supply amount by the air blower 5 is increased to the flow rate at which optimum air-fuel consumption is achieved in S10 after ignition. There is too much to ignite reliably without blowing out the flame. In addition, even if it is determined that the ignition has not been performed in S7, the ignition operation is automatically repeated for a predetermined number of retries in S12, so that the fuel gas pipe in the system is filled with the fuel gas at the first startup after installation. In the absence, the influence of various disturbances such as weather and long-term use can be mitigated, and the equipment can be prevented from being shut down immediately.

  Further, when retrying without ignition, the preheating time for the heater 7 is lengthened, so that the ignition performance at the time of retry can be improved even when the ignition performance of the heater 7 is reduced due to scale adhesion to the heater or the like.

  In the above embodiment, the surplus fuel gas supplied into the fuel cell 4a and not used in the power generation reaction is used as the combustion fuel gas. However, in the present invention, for example, the fuel cell is placed in the storage container. It is also possible to provide a burner for heating the gas and use city gas or the like discharged from the burner as the combustion fuel gas. In this case, since it is not necessary to burn the surplus fuel gas supplied to the fuel battery cell, the surplus fuel gas in the fuel gas supplied to the fuel battery cell can be recovered and reused.

  Moreover, although the form which accommodated the reformer in the storage container 1 was demonstrated in the said form, in this invention, the reformer was provided outside the storage container and the fuel gas reformed by this reformer was supplied. You may comprise so that it may supply to a fuel cell. In this case, a reforming storage container is provided separately from the storage container in which the fuel cells are stored, the reformer is stored in the reforming storage container, and the combustion fuel gas for heating the reformer The present invention can also be used to ignite.

Furthermore, in the above-described embodiment, the case where it is determined that the ignition is detected when the temperature detected by the temperature sensor 8 is equal to or higher than T ₂ (600 ° C.) within the ignition determination time t _{0 of} S 7 has been described. If the temperature detected by the temperature sensor is equal to or higher than T ₂ (600 ° C.), it may be determined that ignition has occurred. In this case, the determination work can be simplified.

It is a schematic block diagram of a fuel cell. 4 is an operation flowchart of the fuel cell operation method of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Storage container 2 ... Gas pump 3 ... Reformer 4 ... Cell stack 4a ... Fuel cell (fuel cell)
5 ... Air blower 7 ... Ignition heater (ignition means)
8 ... Temperature sensor F ... Combustion region

Claims (9)

A fuel cell device comprising: a fuel cell that is supplied with fuel gas and an oxygen-containing gas to generate power; an ignition means that ignites the combustion fuel gas; and a temperature sensor that detects a temperature of a combustion region of the combustion fuel gas. In the start-up method, after the ignition operation is performed on the combustion fuel gas by the ignition means, within a predetermined ignition determination time t ₀ , the temperature T ₀ ° C of the combustion region before ignition is set to a predetermined temperature T _1. ℃ determines that the temperature is ignited when raised above, the ignition if it can be determined that the determination time t ₀ within ignition is determined that the non-firing, to proceed in accordance with the determination of ignition or non-ignition A method for starting a fuel cell device. 2. The method of starting a fuel cell device according to claim 1, wherein the supply of the combustion fuel gas is stopped when it is determined that the ignition has not yet occurred. After performing the ignition operation by the ignition means, if the temperature of the combustion region becomes equal to or higher than the set temperature T ₂ ° C higher than the spontaneous ignition temperature of the combustion fuel gas within the ignition determination time t ₀ , ignition is performed. The method of starting a fuel cell device according to claim 1, wherein it is determined that the fuel cell device has been started. The oxygen-containing gas supply amount is set to be low when the ignition means performs the ignition operation, and the oxygen-containing gas supply amount is increased after it is determined that ignition has occurred. 4. A starting method of a fuel cell device according to any one of the above. When it is determined that the ignition is not ignited, and the supply of the combustion fuel gas is stopped, the ignition operation by the ignition means is repeated again. 5. The method for starting a fuel cell device according to claim 1, wherein after the supply of the fuel gas for combustion is stopped, the ignition operation by the ignition means is stopped. When it is determined that the ignition has not been performed and the supply of the combustion fuel gas is stopped, when the ignition operation by the ignition means is performed again, the oxygen-containing gas supply amount to the combustion region is decreased and the ignition operation by the ignition means is performed. The method of starting a fuel cell device according to any one of claims 1 to 5, wherein: 7. The heater according to claim 1, wherein the ignition means is a heater, and the heater is energized and preheated for a preheating time t ₁ before the supply of the combustion fuel gas is started. A method for starting a fuel cell device. Determines that non-ignition, said after stopping the supply of combustion fuel gas, said when performing the ignition operation by the ignition means again, the ignition operation of the preheating time t ₁ of the heater to be longer than the previous ignition operation 8. The method of starting a fuel cell device according to claim 7, wherein: The method for starting a fuel cell device according to any one of claims 1 to 8, wherein an abnormality is displayed on the display device when it is determined that the ignition has not occurred.

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