JP7650792B2 - Fuel Cell Systems - Google Patents

Description

The present invention relates to a fuel cell system that includes a reforming section that generates a reformed gas containing hydrogen by steam reforming a raw fuel gas containing hydrocarbons that is supplied via a gas meter, a cell stack having an anode to which the reformed gas generated in the reforming section is supplied and a cathode to which oxygen gas is supplied, a combustion section that combusts combustion components contained in the anode exhaust gas discharged from the anode, and a control device.

Gas meters, such as so-called microcomputer meters, are configured to sound an alarm or cut off the supply of raw fuel gas when a state that satisfies a non-leak condition, indicating that the flow rate of raw fuel gas is zero or low, does not occur a set number of times during the leak determination period.

Patent Document 1 describes a technology that aims to prevent the gas meter from issuing an alarm or cutting off the supply of raw fuel gas as described above by intentionally creating a period during which the fuel cell system does not consume raw fuel gas. Specifically, the fuel cell system is controlled to shut down for one day every 27 days (three days before the 30-day period for leak determination has elapsed).

JP 2016-42411 A

As described in Patent Document 1, by stopping the power generation operation of the fuel cell system for one day, the likelihood that the gas meter will determine that a condition satisfying the non-leakage condition has occurred increases; however, during that time the supply of electricity and heat from the fuel cell system is stopped, thereby reducing the benefits to users.
Furthermore, if an unexpected power outage occurs in the power grid while the power generation operation of the fuel cell system is stopped, there is a problem that power generation by the fuel cell system cannot be restarted.

The present invention was made in consideration of the above problems, and its purpose is to provide a fuel cell system that can appropriately create a state that is determined by the gas meter to satisfy the non-leak condition while continuing the power generation operation of the fuel cell system as long as possible, without compromising the benefits to the user as much as possible.

The fuel cell system according to the present invention for achieving the above object comprises a reforming section which steam reforms a raw fuel gas containing hydrocarbons supplied via a gas meter to produce a reformed gas containing hydrogen, a cell stack having a plurality of fuel cell units each having an anode to which the reformed gas produced in the reforming section is supplied and a cathode to which oxygen gas is supplied, a combustion section which combusts combustion components contained in an anode exhaust gas discharged from the anode, a power conditioner which extracts current from the cell stack and supplies the current to a power line connected to a power grid, and a raw fuel supply unit that supplies the raw fuel gas to the reforming unit, a water supply unit that supplies water to the reforming unit, an oxygen supply unit that supplies the oxygen gas to the cathode, and a control device that controls the operation of the raw fuel supply unit, the water supply unit, the oxygen supply unit, and the power conditioner, wherein combustion heat generated in the combustion unit is utilized for steam reforming by the reforming unit, and the raw fuel supply unit, the water supply unit, the oxygen supply unit, and the control device are operable by receiving power supplied from at least one of the power system and the cell stack via the power conditioner,
The gas meter is configured to activate an alarm or cut off the supply of the raw fuel gas when a state satisfying a non-leak condition, which indicates that the flow rate of the raw fuel gas is zero or low, does not occur a set number of times during a leakage determination period,
The control device includes:
a leakage determination avoidance process is performed the set number of times or more, the leakage determination avoidance process including a standby process that transitions from a power generation state in which power generation is performed in the cell stack while generating the reformed gas in an amount that the gas meter determines does not satisfy the non-leak condition for at least the amount of the raw fuel gas received by the reforming unit from the gas meter within a specified processing target period having the same length as the leakage determination period, to a standby state in which the gas meter determines that the non-leak condition is satisfied for at least the amount of the raw fuel gas received by the reforming unit from the gas meter, and the standby state continues for a specified standby period that is longer than a set determination period that is a period for the gas meter to determine whether the non-leak condition is satisfied,
If a voltage drop in the grid power is detected by a voltage detection unit that detects the voltage of the grid power supplied from the power grid to the power line while the leakage determination avoidance process is being performed, a voltage drop response process is performed in which the leakage determination avoidance process is stopped and a transition is made to the power generation state.

According to the above characteristic configuration, the control device performs a leak determination avoidance process a set number of times or more, including a standby process in which, during a predetermined processing period having the same length as the leak determination period, the standby state in which at least the amount of raw fuel gas received by the reforming unit from the gas meter is set to an amount that the gas meter determines satisfies the non-leak condition continues for a predetermined standby period longer than the set determination period, which is a period for the gas meter to determine whether the non-leak condition is satisfied. As a result, the possibility that the gas meter will determine that a state that satisfies the non-leak condition has occurred a set number of times during the leak determination period increases. Furthermore, at least the amount of raw fuel gas received by the reforming unit from the gas meter may be set to an amount that the gas meter determines satisfies the non-leak condition for at least the set determination period. This set determination period is a value set for each gas meter, but if this set determination period is short, the standby period may also be short. Therefore, it is no longer necessary to stop the fuel cell system for one day as in the past.

Furthermore, if the control device detects a voltage drop in the grid power while performing the leakage determination avoidance process, it performs a voltage drop response process to stop the leakage determination avoidance process and transition to the power generation state. As described above, since the standby period can be short, it is expected that the reformer and the cell stack will remain at a high temperature where they can operate even during the standby period. In other words, it is expected that they will be in a state where they can stop the leakage determination avoidance process and immediately transition to the power generation state even during the standby period. As a result, even if a voltage drop in the grid power occurs due to a power outage or the like while performing the leakage determination avoidance process, the fuel cell system can operate independently.
Therefore, it is possible to provide a fuel cell system that can appropriately create a state that is determined by the gas meter to satisfy the non-leakage condition while continuing the power generation operation of the fuel cell system as long as possible, without compromising the benefits to users as much as possible.

Another characteristic feature of the fuel cell system of the present invention is that, during the standby process, the control device sets the amount of raw fuel gas received by the reforming unit from the gas meter to zero, thereby stopping power generation in the cell stack.

According to the above characteristic configuration, the reforming unit reduces the amount of raw fuel gas received from the gas meter to zero, increasing the likelihood that the gas meter will determine that the non-leak condition is met while the standby process is being performed.

Another characteristic feature of the fuel cell system of the present invention is that, during the standby process, the control device receives from the gas meter an amount of the raw fuel gas that the gas meter determines satisfies the non-leak condition at the reforming unit, and generates the reformed gas while generating electricity in the cell stack.

According to the above characteristic configuration, the amount of raw fuel gas that the reforming unit receives from the gas meter is set to an amount that the gas meter determines satisfies the non-leak condition, so that the likelihood that the gas meter will determine that the non-leak condition is satisfied while the standby process is being performed is increased. In addition, while the standby process is being performed, the reforming unit can receive raw fuel gas from the gas meter and generate reformed gas while generating electricity in the cell stack.

A further characteristic configuration of the fuel cell system according to the present invention is an adsorption unit having an adsorbent capable of adsorbing the raw fuel gas upstream of the reforming unit and a temperature adjustment unit capable of adjusting a temperature of the adsorbent,
The control device, during the standby process, controls the temperature of the adsorbent using the temperature control unit, and generates the reformed gas using the raw fuel gas desorbed from the adsorbent while generating electricity in the cell stack.

According to the above characteristic configuration, during standby processing, the reforming section can generate reformed gas using the raw fuel gas desorbed from the adsorption section, and the reformed gas can be used to generate electricity in the cell stack.

A further characteristic configuration of the fuel cell system according to the present invention is an adsorption unit having an adsorbent capable of adsorbing the raw fuel gas upstream of the reforming unit and a temperature adjustment unit capable of adjusting a temperature of the adsorbent,
The control device, during the standby process, reduces the amount of raw fuel gas received by the reforming unit from the gas meter to zero, and generates the reformed gas using the raw fuel gas desorbed from the adsorbent by adjusting the temperature of the adsorbent using the temperature adjustment unit, while generating electricity in the cell stack.

According to the above characteristic configuration, during standby processing, the amount of raw fuel gas that the reforming unit receives from the gas meter is set to zero, while the reforming unit generates reformed gas using the raw fuel gas desorbed from the adsorption unit, and the reformed gas can be used to generate electricity in the cell stack.

Another characteristic configuration of the fuel cell system according to the present invention is to include a cell temperature measuring device that measures a temperature of the cell stack, a voltage measuring device that measures a voltage of the cell stack, and a reforming temperature measuring device that measures a temperature of the reforming section,
The control device performs the voltage drop response processing when a power generation resumption condition is satisfied, the voltage of the cell stack being equal to or higher than a set cell temperature, the voltage of the cell stack being equal to or higher than a set cell voltage, and the temperature of the reforming section being equal to or higher than a set reforming temperature, and does not perform the voltage drop response processing when the power generation resumption condition is not satisfied.

According to the above characteristic configuration, the voltage drop response process is not performed unless the power generation resumption conditions, which include at least one of the following: the temperature of the cell stack is equal to or higher than the set cell temperature, the voltage of the cell stack is equal to or higher than the set cell voltage, and the temperature of the reforming section is equal to or higher than the set reforming temperature, are met. In other words, the voltage drop response process is not performed if it is believed that the fuel cell system cannot operate in the power generation state. As a result, it is possible to avoid the fuel cell system transitioning to the power generation state despite not being able to operate in the power generation state, i.e., to avoid placing an excessive power load on the cell stack and creating the risk of deterioration or failure.

Another characteristic feature of the fuel cell system of the present invention is that it is equipped with a power storage device that can supply power to the power conditioner.

According to the above characteristic configuration, the power supplied from the power storage device is used to supply power to the power conditioner in the voltage drop response process, and the raw fuel supply unit, water supply unit, oxygen supply unit, and control device can be reliably operated with the power supplied from the power conditioner.

FIG. 2 is a diagram showing a state in which the fuel cell system is connected to a power grid. FIG. 1 is a diagram showing a configuration of a fuel cell system. FIG. 13 is a diagram illustrating a processing period. 11A and 11B are diagrams illustrating a leakage determination avoidance process. 11 is a flowchart illustrating an operation related to a leakage determination avoidance process. 13A and 13B are diagrams illustrating a leakage determination avoidance process according to another embodiment. 13A and 13B are diagrams illustrating a leakage determination avoidance process according to another embodiment. FIG. 11 is a diagram showing a state in which a fuel cell system according to another embodiment is connected to a power grid. FIG. 2 is a diagram showing a state in which a fuel cell system and a server device are connected via an information communication line.

A fuel cell system S according to an embodiment of the present invention will now be described with reference to the drawings.
1 is a diagram showing a state in which a fuel cell system S is connected to an electric power system 30. As shown in the figure, the fuel cell system S and a power load device 32 are connected to a power line 31 that is connected to the electric power system 30. As described below, the fuel cell system S includes a cell stack FC having a plurality of fuel cells, each having an anode 8 and a cathode 9, and a power conditioner 37 that extracts current from the cell stack FC and supplies the current to the power line 31 that is connected to the electric power system 30.

In addition, the fuel cell system S includes an auxiliary device 35 and a control device 22. The auxiliary device 35 is equipment necessary for the operation of the fuel cell system S, such as a raw fuel supply unit 5, a water pump 16 as a water supply unit, a circulation pump 18, an air supply unit 15 as an oxygen supply unit, and a temperature adjustment unit 6b, which will be described later.

A circuit breaker 33 is provided on the power line 31. For example, if a power outage occurs in the power grid 30, the circuit breaker 33 opens, electrically disconnecting the fuel cell system S and the power load device 32 from the power grid 30.

The voltage detection unit 34 is provided on the power line 31, upstream of the circuit breaker 33 (on the power system 30 side), and measures the voltage of the system power supplied from the power system 30 to the power line 31. This voltage detection unit 34 is realized, for example, using a voltage transformer. The voltage value measured by the voltage detection unit 34 is transmitted to the fuel cell system S. As a result, the control device 22 of the fuel cell system S can determine a voltage drop in the system power, for example, the occurrence of a power outage in the power system 30. Then, when the control device 22 detects a voltage drop in the system power, it can perform control such as opening the circuit breaker 33.

Figure 2 is a diagram showing the configuration of a fuel cell system S. The fuel cell system S includes a reforming section 7, a cell stack FC having an anode 8 and a cathode 9, a combustion section 11, and a control device 22. In addition, the fuel cell system S of this embodiment includes a raw fuel supply section 5 that supplies raw fuel gas to the reforming section 7, an adsorption section 6, an air supply section 15 as an oxygen supply section that supplies oxygen gas (air) to the cathode 9, a heat exchanger 12, a water purifier 13, a water tank 14, and a water pump 16 as a water supply section that supplies water to the reforming section 7.

The reforming unit 7 generates reformed gas containing hydrogen by steam reforming raw fuel gas, such as city gas, which is supplied via the gas meter 1 and the raw fuel gas flow passage L1b (L1). The flow rate per unit time of the raw fuel gas received by the reforming unit 7 from the gas meter 1 is adjusted by the raw fuel supply unit 5. The raw fuel gas whose flow rate has been adjusted by the raw fuel supply unit 5 is then supplied to the reforming unit 7 via the adsorption unit 6. The reforming unit 7 is provided with a reforming temperature measuring device 7a that measures the temperature of the reforming unit 7. The measurement result of the reforming temperature measuring device 7a is transmitted to the control device 22.

In addition, water stored in a water tank 14 is supplied to the reforming unit 7 via a water pump 16 and a water flow path L10, and the water is used for steam reforming of the raw fuel gas. Although not shown, a vaporizer for vaporizing the supplied water may be provided.
The operation of the raw fuel supply unit 5 is controlled by a control device 22 .

The adsorption section 6 has an adsorbent 6a capable of adsorbing raw fuel gas upstream of the reforming section 7 and a temperature adjustment section 6b capable of adjusting the temperature of the adsorbent 6a. The adsorbent 6a adsorbs the raw fuel gas when the temperature is low, and desorbs the adsorbed raw fuel gas when the temperature is high. Therefore, the control device 22 can desorb the raw fuel gas from the adsorbent 6a by adjusting the temperature of the adsorbent 6a using the temperature adjustment section 6b, which is realized by using, for example, an electric heater. For example, the adsorbent 6a can be realized by using activated carbon or zeolite, and in this case, the adsorbed raw fuel gas can be desorbed by setting the temperature of the adsorbent 6a to about 100°C to 200°C or higher. Note that the adsorbent 6a may be made of, for example, silver zeolite, and may also be configured to function as a desulfurizing agent for removing sulfur from city gas.
The operation of the temperature adjusting unit 6b is controlled by the control device 22.

The reformed gas generated in the reforming unit 7 is supplied to the cell stack FC via the reformed gas flow path L2. In addition, oxygen gas (air) is supplied to the cell stack FC via the air flow path L4. The flow rate per unit time of the air (i.e., oxygen) supplied to the cathode 9 of the cell stack FC is adjusted by the air supply unit 15. The cell stack FC has an anode 8 to which the reformed gas generated in the reforming unit 7 is supplied, a cathode 9 to which oxygen gas is supplied, and an electrolyte layer 10 provided between them. For example, the electrolyte layer 10 is configured using a solid oxide, and in that case, the cell stack FC has a solid oxide type power generation cell. The cell stack FC is provided with a cell temperature measuring device 28 that measures the temperature of the cell stack FC and a cell voltage measuring device 29 that measures the voltage of the cell stack FC. The measurement results of the cell temperature measuring device 28 and the cell voltage measuring device 29 are transmitted to the control device 22.
The operation of the air supply unit 15 is controlled by a control device 22 .

The control device 22 controls the operation of the raw fuel supply unit 5, the water pump 16, the circulation pump 18, the air supply unit 15, the power conditioner 37, etc. The raw fuel supply unit 5, the water pump 16 as a water supply unit, the circulation pump 18, the air supply unit 15 as an oxygen supply unit, the auxiliary equipment 35 such as the temperature adjustment unit 6b, and the control device 22 can operate by receiving power supply from at least one of the power system 30 and the cell stack FC via the power conditioner 37.

The anode exhaust gas discharged from the anode 8 is supplied to the combustion section 11 via the anode exhaust gas flow passage L3. The cathode exhaust gas discharged from the cathode 9 is supplied to the combustion section 11 via the cathode exhaust gas flow passage L5. For example, the anode exhaust gas flow passage L3 is an anode exhaust gas pipe through which the anode exhaust gas supplied from the anode 8 to the combustion section 11 flows. Also, for example, the cathode exhaust gas flow passage L5 is a cathode exhaust gas pipe through which the cathode exhaust gas supplied from the cathode 9 to the combustion section 11 flows.

The combustion section 11 combusts the combustion components contained in the anode exhaust gas discharged from the anode 8. The combustion section 11 is also supplied with the cathode exhaust gas discharged from the cathode 9, and the oxygen contained in the cathode exhaust gas is used for combustion. The combustion heat generated in the combustion section 11 is used for steam reforming of the raw fuel gas by the reforming section 7. If a vaporizer is provided, the combustion heat is supplied to the vaporizer and used to vaporize water.

The exhaust combustion gas discharged from the combustion section 11 is supplied to the heat exchanger 12 via the exhaust combustion gas flow path L6. The heat exchanger 12 is also supplied with hot and cold water flowing through the hot and cold water circulation path L7. Then, the heat exchanger 12 exchanges heat between the exhaust combustion gas and the hot and cold water. In this embodiment, this heat exchange cools the exhaust combustion gas and heats the hot and cold water flowing through the hot and cold water circulation path L7.

The hot water circulation path L7 circulates hot water between the hot water storage tank 17 and the heat exchanger 12. The hot water storage tank 17 stores hot water in a state in which relatively low temperature hot water is stored at the bottom and relatively high temperature hot water is stored at the top, that is, in a state in which temperature stratification is formed. To be more specific, the hot water circulation path L7 is composed of an outgoing path that transports hot water from the hot water storage tank 17 to the heat exchanger 12, and a return path that transports hot water from the heat exchanger 12 to the hot water storage tank 17, and has a circulation pump 18 installed midway along the outgoing path.

With this configuration, hot water supplied from the bottom of the hot water storage tank 17 to the heat exchanger 12 through the outward path of the hot water circulation path L7 is heated by the heat exchanger 12, and the heated hot water is supplied to the top of the hot water storage tank 17 through the return path of the hot water circulation path L7. A temperature measurement unit 19 is provided on the return path to measure the temperature of the hot water transferred from the heat exchanger 12 to the hot water storage tank 17. In this embodiment, the control device 22 controls the operation of the circulation pump 18 so that the temperature of the hot water flowing through the return path and into the hot water storage tank 17 (the temperature of the hot water measured by the temperature measurement unit 19) becomes a predetermined hot water storage target temperature (for example, 65°C). In this way, the hot water is stored in the hot water storage tank 17 in a state where temperature stratification is formed, i.e., heat is stored.

The lower part of the hot water storage tank 17 is connected to a water supply line L8a (L8) for supplying clean water to the hot water storage tank 17, and the upper part of the hot water storage tank 17 is connected to a hot water outlet line L9 for discharging the hot water stored in the hot water storage tank 17. A water supply line L8b (L8) is connected to the middle of the hot water outlet line L9, and clean water can be mixed with the hot water discharged from the hot water storage tank 17. The amount of clean water mixed with the hot water discharged from the hot water storage tank 17 is adjusted by an adjustment valve 21 provided in the middle of the water supply line L8b. For example, the control device 22 controls the operation of the adjustment valve 21 so that the temperature of the hot water after mixing measured by the temperature measurement unit 20 becomes a predetermined temperature (e.g. 30°C). The hot water after mixing is then supplied to the user via the heat source device 4.

The heat source device 4 functions as a gas consumption device 2 that burns raw fuel gas supplied via the gas meter 1 and heats hot water with the combustion heat. For example, if the information receiving unit 23 receives a request for hot water at 40°C from a user, the control device 22 heats the hot water to 40°C using the heat source device 4 and supplies it to the user.

The exhaust combustion gas discharged from the combustion section 11 also contains water vapor. Therefore, when the exhaust combustion gas is cooled by the heat exchanger 12, the water vapor is condensed. Then, the condensed water flows into the water recovery passage L11. The recovered condensed water is supplied to the water tank 14 via the water purifier 13. The water purifier 13 is a device for removing impurities contained in the recovered condensed water. For example, the water purifier 13 is filled with an ion exchange resin or the like, and serves to relatively lower the concentration of electrolytes contained in the recovered condensed water (i.e., to lower the electrical conductivity) by exchanging ions of electrolytes (e.g., ionized and dissolved salts, ammonia, etc.) contained in the recovered condensed water with, for example, H ⁺ or OH ⁻ .

The gas meter 1 is configured to activate an alarm or cut off the supply of raw fuel gas when a state that satisfies the non-leak condition, which indicates that the flow rate of raw fuel gas is zero or low, does not occur a set number of times (e.g., 30 times) during a leak determination period (e.g., the past 30 days). For example, the gas meter 1 determines that a state that satisfies the non-leak condition has occurred when a state in which the flow rate of raw fuel gas is equal to or less than a first set determination amount continues for more than a first set determination period (e.g., 2 minutes), or when the cumulative flow rate of raw fuel gas during a second set determination period (e.g., 2 minutes) is equal to or less than a second set determination amount.

In the configuration illustrated in FIG. 1, the gas meter 1 supplies raw fuel gas to the reforming unit 7 of the fuel cell system S through the raw fuel gas flow path L1b (L1), and to the heat source device 4 of the fuel cell system S through the raw fuel gas flow path L1c (L1). The gas meter 1 also supplies raw fuel gas to the gas appliance 3 as a gas consumption device 2 such as a gas stove or a gas combustion fan heater through the raw fuel gas flow path L1a (L1). Therefore, the gas meter 1 judges whether or not a state that satisfies a non-leak condition has occurred with respect to the consumption of raw fuel gas in, for example, the reforming unit 7, the heat source device 4, and all of the gas appliances 3. If such a state that satisfies the non-leak condition has occurred a set number of times (e.g., 30 times) during the leak judgment period (e.g., the past 30 days), the gas meter 1 judges that there is no abnormality and resets the timer for the leak judgment period to zero.

The control device 22 of the fuel cell system S performs, at a set timing, the amount of raw fuel gas received by the reforming unit 7 from the gas meter 1 to an amount that the gas meter 1 determines satisfies the non-leak condition, so that the gas meter 1 determines that a state that satisfies the non-leak condition has occurred a set number of times during the leak determination period. Specifically, the control device 22 transitions from a power generation state in which power is generated in the cell stack FC while generating reformed gas at an amount that the gas meter 1 determines does not satisfy the non-leak condition for at least the amount of raw fuel gas received by the reforming unit 7 from the gas meter 1 during a specified processing target period having the same length as the leak determination period, to a standby state in which the amount of raw fuel gas received by the reforming unit 7 from the gas meter 1 to an amount that the gas meter 1 determines satisfies the non-leak condition, and performs a leak determination avoidance process including a standby process that continues for a predetermined standby period longer than the setting determination period (e.g., the above-mentioned first setting determination period, second setting determination period, etc.) that is a period for the gas meter 1 to determine whether the non-leak condition is satisfied, for a set number of times or more.

For example, in the standby process, the control device 22 sets the amount of raw fuel gas that the reforming unit 7 receives from the gas meter 1 to zero, and stops power generation in the cell stack FC. Then, for example, if the leak determination period is 30 days, the control device 22 performs the leak determination avoidance process, which includes a standby process that lasts for a standby period of, for example, 3 minutes, which is longer than the set determination period of 2 minutes of the gas meter 1, for example, 31 times or more within the processing target period of 30 days that is the same length as the leak determination period. In other words, in this example, the standby period is set to be 1 minute longer than the set determination period of the gas meter 1, and the number of times the leak determination avoidance process is performed within the processing target period of 30 days is set to be 1 more than the set number of times of the gas meter 1.

Figure 3 is a diagram explaining the processing period for performing the leak detection avoidance process a set number of times or more. As shown in the figure, the control device 22 determines an implementation schedule for the leak detection avoidance process, including the standby process, so that at any point in time, the standby process is performed a predetermined planned number of times, which is equal to or greater than the set number, within a period from that point in time that is the same length as the future leak detection period. In the example shown in Figure 3, the planned implementation timings for 31 leak detection avoidance process times, from T1 to T31, are set.

The scheduled execution timing of the leak determination avoidance process can be set appropriately. For example, the control device 22 may prioritize the leak determination avoidance process during a time period when the heat source device 4 as the gas consumption device 2, which consumes the raw fuel gas supplied via the same gas meter 1 as the reforming unit 7 receives the raw fuel gas, is unlikely to perform a gas consumption operation. In that case, the control device 22 stores the number of times that the raw fuel gas is consumed by the heat source device 4 as the gas consumption device 2, and derives, for example, the frequency of the gas consumption operation per hour in a day. Then, the control device 22 prioritizes the leak determination avoidance process during a time period when the frequency of the gas consumption operation is low in a day. For example, if the control device 22 determines that the time periods when the frequency of the gas consumption operation is low in a day are 2:00 and 4:00, the control device 22 plans to perform the leak determination avoidance process twice in a day, at 2:00 and 4:00. In this case, an implementation schedule is set for performing the leak determination avoidance process 60 times in the future 30 days (720 hours). Therefore, since there is an increased likelihood that a state will occur in which the gas meter 1 determines that the non-leak condition is met while the leak determination avoidance process is being performed, there is an increased likelihood that the gas meter 1 will determine that a state in which the non-leak condition is met has occurred a set number of times during the leak determination period.

Figure 4 is a diagram explaining the leak determination avoidance process. In the example shown in Figure 4, the leak determination avoidance process includes pre-processing, standby processing, and post-processing. Pre-processing is performed between time Ta and time Tb, standby processing is performed between time Tb and time Tc, and post-processing is performed between time Tc and time Td. The leak determination avoidance process may include pre-processing and standby processing, or it may include standby processing and post-processing.

Specifically, as a leakage determination avoidance process, the control device 22 performs a pre-processing between times Ta and Tb in which the reforming unit 7 continues to receive raw fuel gas from the gas meter 1 while stopping power generation in the cell stack FC, performs a standby process after the pre-processing, and combusts the anode exhaust gas discharged from the anode 8 in the combustion unit 11 while the pre-processing is being performed.

For example, in the pre-processing, the control device 22 controls the operation of the power conditioner 37 between times Ta and Tb to not extract current (power generation) from the cell stack FC, i.e., to stop power generation in the cell stack FC. However, between times Ta and Tb, the control device 22 operates the raw fuel supply unit 5 to continue supplying raw fuel gas to the reforming unit 7, and operates the air supply unit 15 to continue supplying air to the cathode 9. In addition, between times Ta and Tb, the control device 22 operates the water pump 16 to continue supplying water to the reforming unit 7. Furthermore, in the combustion unit 11, combustion components contained in the anode exhaust gas discharged from the anode 8 are combusted, and the combustion heat is supplied to the reforming unit 7. Therefore, between times Ta and Tb, the reformed gas generated in the reforming unit 7 is combusted in the combustion unit 11 without being used for power generation in the cell stack FC.

In this way, the anode exhaust gas (i.e., high-concentration raw fuel gas) discharged from the anode 8 during pre-processing is combusted in the combustion unit 11, so that at the start of the standby process, the combustion heat emitted from the combustion unit 11 causes the temperature inside the hot module housing, for example, the reformer 7, the cell stack FC, and the combustion unit 11 to become high. As a result, even if the temperature of the reformer 7 drops during the subsequent standby process, the temperature at the end of the standby process can be made high, and the deterioration effect on the cell stack FC due to temperature changes can be suppressed. In addition, the raw fuel gas is supplied to the reformer 7 in the pre-processing, increasing the concentration of the raw fuel gas, so that power generation in the cell stack FC can be quickly performed when the voltage drop response process described below is performed thereafter.

In addition, during the standby process, the control device 22 stops the operation of the raw fuel supply unit 5 to stop the supply of raw fuel gas to the reforming unit 7 between times Tb and Tc, stops the reforming unit 7 from receiving raw fuel gas from the gas meter 1, and stops the operation of the air supply unit 15 to stop the supply of air to the cathode 9. During the standby process, the control device 22 controls the operation of the power conditioner 37 between times Tb and Tc to not extract current from the cell stack FC. Note that during the standby process, the control device 22 operates the water pump 16 to continue to supply water to the reforming unit 7. Therefore, only water vapor continues to be supplied from the reforming unit 7 to the anode 8 between times Tb and Tc. In this way, during the standby process, a mixed gas of water vapor and the fuel gas filled in the reforming unit 7 is supplied from the reforming unit 7 to the anode 8. Therefore, during the standby process, air or the like from the outside enters the anode 8, etc., and the anode 8 is prevented from being oxidized and deteriorated. Furthermore, a decrease in the S/C (steam/carbon ratio) of the gas supplied to the anode 8 during standby processing or immediately after power generation is resumed is suppressed.

In addition, as a leakage determination avoidance process, the control device 22 performs a post-processing between time Tc and time Td after the standby process, in which the reforming unit 7 resumes receiving raw fuel gas from the gas meter 1 and generates reformed gas while stopping power generation in the cell stack FC, and combusts the anode exhaust gas discharged from the anode 8 in the combustion unit 11 while the post-processing is being performed.

For example, in the post-processing, the control device 22 controls the operation of the power conditioner 37 between time Tc and time Td so as not to extract current from the cell stack FC. However, between time Tc and time Td, the control device 22 operates the raw fuel supply unit 5 to continue supplying raw fuel gas to the reforming unit 7, and operates the air supply unit 15 to continue supplying air to the cathode 9. In addition, between time Tc and time Td, the control device 22 operates the water pump 16 to continue supplying water to the reforming unit 7. Furthermore, in the combustion unit 11, combustion components contained in the anode exhaust gas discharged from the anode 8 are combusted, and the combustion heat is supplied to the reforming unit 7. Therefore, between time Tc and time Td, the reformed gas generated in the reforming unit 7 is combusted in the combustion unit 11 without being used for power generation in the cell stack FC.

FIG. 5 is a flowchart illustrating the operation of the control device 22 regarding the leakage determination avoidance process.
In step #10, the control device 22 judges whether it is the timing to start the leakage determination avoidance process. For example, the control device 22 judges whether it is the time Ta illustrated in FIG. 4. Then, when it is the timing to start the leakage determination avoidance process, the control device 22 proceeds to step #11 and starts the leakage determination avoidance process. In the example described in FIG. 4, the control device 22 performs pre-processing of the leakage determination avoidance process between time Ta and time Tb, and starts standby processing as the leakage determination avoidance process from time Tb. Then, while performing standby processing of the leakage determination avoidance process, the control device 22 monitors the operation of the heat source device 4 as the gas consumption device 2 (i.e., the gas combustion operation).

Then, in step #12, the control device 22 determines whether it is time to end the standby process of the leak determination avoidance process. In the example shown in FIG. 4, the control device 22 determines whether time Tc has arrived. If it is time to end the standby process, the control device 22 proceeds to step #13 and ends the standby process of the leak determination avoidance process.

Next, in step #14, when the end timing of the leak determination avoidance processing has arrived, the control device 22 proceeds to step #15 and ends the leak determination avoidance processing. In the case of the example shown in FIG. 4, when the control device 22 determines that it has reached time Td, which is the end timing of the post-processing of the leak determination avoidance processing, it ends the post-processing, i.e., ends the leak determination avoidance processing.

The control device 22 monitors whether or not there has been a gas consumption operation by the heat source device 4 as the gas consumption device 2 while performing the standby process of the leakage determination avoidance process. If there has been a gas consumption operation by the heat source device 4 as the gas consumption device 2 while performing the standby process of the leakage determination avoidance process, that is, if the standby process has failed, the control device 22 can infer that the gas meter 1 has not determined that a state satisfying the non-leak condition has occurred during the standby process. Therefore, if the number of standby processes in which there was no gas consumption operation by the heat source device 4 during a processing target period, such as 30 days in the past, that is, the number of successful standby processes, is less than a set number such as 30 times, the control device 22 can infer that the gas meter 1 has also determined that a state satisfying the non-leak condition has not occurred a set number such as 30 times during the leakage determination period in the past such as 30 days. In that case, the control device 22 may use a remote control device or the like that displays the operating state of the fuel cell system S to notify the user by voice information or text information that there is a high possibility that an alarm has been activated by the gas meter 1 or that the supply of raw fuel gas has been cut off.

The control device 22 may operate to set an additional standby process if a gas consumption operation is performed by the heat source device 4 as the gas consumption device 2 while the standby process for the leak determination avoidance process is being performed. In other words, the control device 22 may operate to reset the implementation schedule for the leak determination avoidance process. Note that, if there is a gas consumption device 2 whose operating state can be monitored separate from the heat source device 4, the control device 22 may operate to reset the implementation schedule for the leak determination avoidance process, including the monitoring results of the operating state of the gas consumption device 2.

Specifically, the control device 22 can reset the execution schedule of the leak determination avoidance process by setting the additional standby process to a timing for extending the standby process currently being performed or the standby process to be performed in the future. For example, the control device 22 monitors the operating state of at least some of the gas consumption devices 2 that consume raw fuel gas supplied via the gas meter 1, and when the gas consumption device 2 consumes raw fuel gas during the standby process of the leak determination avoidance process, the control device 22 extends the length of the standby period of the standby process currently being performed or the standby process to be performed in the future. In the case of the example shown in FIG. 4, the control device 22 resets the stop timing of the standby process to a later time Tc+α, rather than to time Tc. In other words, the control device 22 resets the execution schedule of the leak determination avoidance process such that the standby process currently being performed is extended by the period α. In that case, the end timing of the post-stop process is also reset to time Td+α. For example, in the above example, the case where the standby period is set to 3 minutes has been described, but the extension length "α" of the standby period can be set to, for example, 2 minutes, resulting in a total of 5 minutes for one standby period.

When the gas consumption operation by the heat source device 4 as the gas consumption device 2 continues, the standby process may be extended repeatedly, which may result in a single standby period being longer. In this case, an upper limit may be set for the length of a single standby period, such as 20 minutes. The control device 22 may then forcibly stop the standby process when the length of a single standby period reaches, for example, 20 minutes. When the control device 22 forcibly stops the standby process, it may also extend the length of the standby period for the next standby process, or add a new leak determination avoidance process within the currently set target processing period, as described below.

In addition, the control device 22 can reset the execution schedule of the leak determination avoidance process by setting it to add a new leak determination avoidance process within the currently set processing target period. For example, the control device 22 monitors the operating state of the gas consumption device 2 that consumes the raw fuel gas supplied via the gas meter 1, and if the gas consumption device 2 consumes the raw fuel gas during the standby process of the leak determination avoidance process, the control device 22 increases the planned number of times the leak determination avoidance process is executed. In the example shown in FIG. 3, the control device 22 sets a schedule to add one new leak determination avoidance process between the present time and the planned execution timing of the leak determination avoidance process of T31. For example, if the present time is 5:00 a.m. and the originally scheduled execution timing of the next leak determination avoidance process is 2:00 a.m. the next day, the control device 22 adds a schedule to execute one new leak determination avoidance process until then, for example, at 11:00 p.m. on the current day.

As described above, the control device 22 performs the leak determination avoidance process, including the standby process of stopping the receipt of raw fuel gas from the gas meter 1 for the standby period, a set number of times or more within a predetermined processing target period that is the same length as the leak determination period. As a result, the possibility that the gas meter 1 will determine that a state that satisfies the non-leak condition has occurred a set number of times during the leak determination period increases. Furthermore, the reforming unit 7 of the fuel cell system S only needs to stop receiving raw fuel gas from the gas meter 1 for at least the set determination time. This set determination time is a value that is set for each gas meter, but if this set determination time is short, the standby period during which the reforming unit 7 of the fuel cell system S stops receiving raw fuel gas from the gas meter 1 can also be short. Therefore, it is no longer necessary to stop the fuel cell system S for one day as in the past.

Next, a voltage drop response process will be described, in which power generation in the cell stack FC is resumed while the leakage determination avoidance process is being performed when a predetermined condition is satisfied.
If the control device 22 detects a voltage drop in the system power by the voltage detection unit 34, which detects the voltage of the system power supplied from the power system 30 to the power line 31, while performing the leakage determination avoidance process, the control device 22 performs a voltage drop response process to stop the leakage determination avoidance process and transition to the above-mentioned power generation state. Specifically, in the voltage drop response process, the control device 22 operates the raw fuel supply unit 5, the water pump 16, the circulation pump 18, and the air supply unit 15, and causes the power conditioner 37 to extract current from the cell stack FC (generate electricity) while generating reformed gas by setting at least the amount of raw fuel gas received by the reforming unit 7 from the gas meter 1 to an amount that the gas meter 1 determines does not satisfy the non-leak condition.

Specifically, the control device 22 continues to monitor the voltage of the grid power detected by the voltage detection unit 34 while performing the leakage determination avoidance process. Then, when the voltage of the grid power detected by the voltage detection unit 34 is equal to or lower than a predetermined lower limit voltage, the control device 22 performs the above-mentioned voltage drop response process. As described above, since the standby period during which the reformer 7 of the fuel cell system S stops receiving the raw fuel gas from the gas meter 1 may be short, it is expected that the reformer 7 and the cell stack FC will remain at a high temperature at which they can operate even during the standby period. In other words, it is expected that they will be in a state in which they can immediately stop the leakage determination avoidance process and transition to the above-mentioned power generation state even during the standby period. As a result, even if a voltage drop in the grid power occurs due to a power outage or the like while performing the leakage determination avoidance process, the fuel cell system S can operate independently.

When the temperature of the cell stack FC is low, when the temperature of the reforming unit 7 is low, when the voltage of the cell stack FC is low, etc., if the power conditioner 37 forcibly draws current from the cell stack FC, there is a risk of degradation or failure of the cell stack FC. Therefore, the control device 22 performs a voltage drop response process when the power generation restart condition including at least one of the following is satisfied: the temperature of the cell stack FC is equal to or higher than the set cell temperature, the voltage of the cell stack FC is equal to or higher than the set cell voltage, and the temperature of the reforming unit 7 is equal to or higher than the set reforming temperature, and does not perform a voltage drop response process when the power generation restart condition is not satisfied. In other words, if it is considered that the fuel cell system S cannot operate in the above power generation state, the voltage drop response process is not performed. As a result, the fuel cell system S does not transition to the above power generation state even though it cannot operate in the above power generation state, that is, it is avoided that an excessive power load is applied to the cell stack FC, resulting in the risk of degradation or failure.

<Another embodiment>
＜1＞
In the above embodiment, the configuration of the fuel cell system S has been specifically described, but the configuration can be modified as appropriate.

＜2＞
In the above embodiment, the control device 22 may adjust the temperature of the adsorbent 6a by the temperature adjustment unit 6b during the standby process to desorb the raw fuel gas from the adsorbent 6a.

For example, during standby processing, the control device 22 may set the amount of raw fuel gas received by the reforming unit 7 from the gas meter 1 to zero, i.e., a state in which the gas meter 1 determines that the non-leak condition is satisfied, and stop power generation in the cell stack FC, while controlling the temperature of the adsorbent 6a using the temperature control unit 6b to desorb the raw fuel gas from the adsorbent 6a. In this case, the raw fuel gas desorbed from the adsorbent 6a during standby processing diffuses through the reforming unit 7 to the anode 8. Therefore, the intrusion of air or the like from the outside into the anode 8 and the like during standby processing of the leak determination avoidance processing is suppressed.

Alternatively, the control device 22 may, in the standby process, cause the cell stack FC to generate power while the reforming unit 7 generates reformed gas using the raw fuel gas desorbed from the adsorbent 6a by adjusting the temperature of the adsorbent 6a using the temperature adjustment unit 6b. FIG. 6 is a diagram for explaining a leak determination avoidance process of another embodiment. In the example shown in FIG. 6, the leak determination avoidance process includes a standby process performed between time Tb and time Tc. In this case, the control device 22, in the standby process, causes the amount of raw fuel gas received by the reforming unit 7 from the gas meter 1 to be zero, that is, causes the gas meter 1 to be in a state in which it is determined that the non-leak condition is satisfied, and causes the cell stack FC to generate power while the reforming unit 7 generates reformed gas using the raw fuel gas desorbed from the adsorbent 6a by adjusting the temperature of the adsorbent 6a using the temperature adjustment unit 6b. The raw fuel gas desorbed from the adsorbent 6a is diffused and supplied to the reforming unit 7, but if the amount of raw fuel gas received by the reforming unit 7 from the gas meter 1 is set to zero, the gas meter 1 determines that the non-leak condition is satisfied. The reforming unit 7 can generate reformed gas using the raw fuel gas desorbed from the adsorbent 6a, so the control unit 22 can extract (generate) current from the cell stack FC. However, the continued power generation performed in this standby process is continued in an idling state in which the generated power of the cell stack FC is supplied via the power conditioner 37 only to auxiliary equipment 35, such as the raw fuel supply unit 5, water pump 16, circulation pump 18, air supply unit 15, and temperature adjustment unit 6b, which are necessary to operate the cell stack FC, and to the control unit 22.

In the example shown in FIG. 6, the details of the operations performed between time Ta and time Tb and between time Tc and time Td can be set as appropriate. For example, the operations performed between time Ta and time Tb may be the same as or different from the operations performed before time Ta. Similarly, the operations performed between time Tc and time Td may be the same as or different from the operations performed after time Td.

＜3＞
In the above embodiment, an example has been described in which the control device 22 sets the amount of raw fuel gas received by the reforming unit 7 from the gas meter 1 to zero during standby processing (i.e., sets the amount to an amount that the gas meter 1 determines satisfies the non-leak condition), but if the gas meter 1 determines that the non-leak condition is satisfied, the reforming unit 7 may receive raw fuel gas from the gas meter 1. Then, the control device 22 may cause the cell stack FC to generate power while receiving at least an amount of raw fuel gas that the gas meter 1 determines satisfies the non-leak condition during standby processing from the gas meter 1 at the reforming unit 7 and generating the reformed gas.

Figure 7 is a diagram illustrating a leakage determination avoidance process of another embodiment. In the example shown in Figure 7, the leakage determination avoidance process includes a standby process performed between time Tb and time Tc. In this case, the control device 22 receives from the gas meter 1 in the reforming unit 7 an amount of raw fuel gas that the gas meter 1 determines to satisfy the non-leak condition in the standby process. For example, as in the above example, if the gas meter 1 determines that the non-leak condition is satisfied when the state in which the flow rate of the raw fuel gas is equal to or less than the first set determination amount continues for more than the first set determination period, the control device 22 may control the operation of the raw fuel supply unit 5 in this standby process to keep the flow rate of the raw fuel gas to the reforming unit 7 equal to or less than the first set determination amount, and allow the reforming unit 7 to continue receiving the raw fuel gas from the gas meter 1. Alternatively, if the gas meter 1 determines that a state satisfying the non-leak condition has occurred, for example, when the cumulative flow rate of the raw fuel gas during the second set judgment period is equal to or less than the second set judgment amount, the control device 22 controls the operation of the raw fuel supply unit 5 in this standby process to keep the cumulative flow rate of the raw fuel gas during the same period as the second set judgment period equal to or less than the second set judgment amount, and allows the reforming unit 7 to continue receiving the raw fuel gas from the gas meter 1. The reforming unit 7 can then generate reformed gas using the raw fuel gas received from the gas meter 1, so that the control device 22 can extract (generate) current from the cell stack FC. However, the continued power generation during this standby process is the same as that described above, in an idling state.

Furthermore, in the standby process, the control device 22 may receive from the gas meter 1 at the reforming unit 7 an amount of raw fuel gas that the gas meter 1 determines satisfies the non-leak condition, and may use the raw fuel gas desorbed from the adsorbent 6a by adjusting the temperature of the adsorbent 6a using the temperature adjustment unit 6b to generate reformed gas in the reforming unit 7 while generating electricity in the cell stack FC.

In the example shown in FIG. 7, the details of the operations performed between time Ta and time Tb and between time Tc and time Td can be set as appropriate. For example, the operations performed between time Ta and time Tb may be the same as the operations performed before time Ta, or they may be different. Similarly, the operations performed between time Tc and time Td may be the same as the operations performed after time Td, or they may be different.

＜4＞
In the above embodiment, an example has been described in which the reforming unit 7 continues to receive water for steam reforming while the leak determination avoidance processing is being performed. However, for example, the reforming unit 7 may stop receiving water for steam reforming while the standby processing for the leak determination avoidance processing is being performed.

＜5＞
In the above embodiment, the fuel cell system S may include a power storage device 36 capable of supplying power to the power conditioner 37. FIG. 8 is a diagram showing a state in which a fuel cell system S according to another embodiment is connected to a power grid 30. As shown in the figure, the fuel cell system S includes a power storage device 36. This power storage device 36 is electrically connected to the auxiliary equipment 35, the control device 22, and the like via the power conditioner 37, and can supply power to them. In other words, the power supplied from the power storage device 36 is used to supply power to the power conditioner 37 in the voltage drop response process, and the raw fuel supply unit 5, the water pump 16, the circulation pump 18, the air supply unit 15, the temperature adjustment unit 6b, and the control device 22 can be reliably operated with the power supplied from the power conditioner 37. In addition, since the power storage device 36 is connected to the power line 31 via the power conditioner 37, it can receive power from the power line 31 and store the power.

＜6＞
In the above embodiment, an information receiving unit 23 is provided that receives gas meter 1 information that can identify the setting determination period (first setting determination period, first setting determination period), the setting determination flow rate (first setting determination flow rate, second setting determination flow rate), the leak determination period, the setting count, etc., related to the gas meter 1, and the control device 22 may perform leak determination avoidance processing based on the gas meter 1 information received by the information receiving unit 23.

Figure 9 is a diagram showing a state in which a fuel cell system S and a server device 26 are connected via an information and communication line 25. As shown in the figure, a gas meter 1 and a fuel cell system S as exemplified in Figure 2 are installed in a facility 27 such as a residence or a business office. The server device 26 stores gas meter 1 information regarding the gas meters 1 installed in each of the multiple facilities 27.

The server device 26 transmits gas meter information of the gas meter 1 installed in the same facility 27 as the fuel cell system S to the fuel cell system S via the information communication line 25. The fuel cell system S stores the received gas meter information in the information storage unit 24. When performing leakage determination avoidance processing, the control device 22 of the fuel cell system S refers to the gas meter information stored in the information storage unit 24 to determine the length of the processing period, the length of the standby period, the planned number of times the leakage determination avoidance processing is to be performed during the processing period, the amount of raw fuel gas that the reforming unit 7 receives from the gas meter 1, etc.

＜７＞
In the above embodiment, numerical examples are given for the length of the processing period, the length of the waiting period, the planned number of times the leak detection avoidance processing is performed during the processing period, and the execution schedule, but these values are given for illustrative purposes and can be changed as appropriate.

＜8＞
In the above embodiment, the case where the heat source device 4 as the gas consumption device 2 is used for hot water supply to the user has been described, but the heat source device 4 as the gas consumption device 2 may be, for example, a heating heat source device 4 for heating a heat medium to be supplied to a floor heating device and a bathroom heating and drying device. When the heat source device 4 is used for such a heating purpose, even if the heat source device 4 temporarily stops the gas consumption operation and stops heating the heat medium, it is unlikely that the user of the floor heating device or the bathroom heating and drying device will be able to feel it. Therefore, while performing the above standby process, the control device 22 may prevent the heat source device 4 as the gas consumption device 2 that consumes the raw fuel gas supplied via the same gas meter 1 through which the reforming unit 7 receives the raw fuel gas from performing a gas consumption operation. Note that the control device 22 cannot prevent the gas consumption operation of all the gas consumption devices 2 that receive the raw fuel gas from the gas meter 1. For example, the control device 22 can prevent the gas consumption operation of the heat source device 4 included in the fuel cell system S, for example, but cannot prevent the gas consumption operation of the gas appliance 3 shown in FIG. 2 and the like.

In this way, during standby processing, the reforming unit 7 is prevented from using gas in the gas consumption device 2 that consumes the raw fuel gas supplied via the same gas meter 1 through which the raw fuel gas is supplied, thereby further increasing the possibility of a state occurring in which the gas meter 1 determines that the non-leak condition is satisfied. As a result, the possibility that the control device 22 must set an additional standby process as described above can be reduced.

＜9＞
Furthermore, the configurations disclosed in the above embodiments (including other embodiments, the same applies below) can be applied in combination with configurations disclosed in other embodiments, provided no contradiction arises. Furthermore, the embodiments disclosed in this specification are merely examples, and the embodiments of the present invention are not limited thereto, and can be appropriately modified within the scope that does not deviate from the purpose of the present invention.

The present invention can be used in fuel cell systems that can appropriately create a non-leakage state without compromising the benefits to users as much as possible.

1: Gas meter 5: Raw fuel supply section 7: Reforming section 7a: Reforming temperature measuring device 8: Anode 9: Cathode 11: Combustion section 15: Air supply section (oxygen supply section)
16: Water pump (water supply section)
22: Control device 28: Cell temperature measuring device 30: Power system 31: Power line 34: Voltage detection unit 36: Power storage device 37: Power conditioner FC: Cell stack S: Fuel cell system

Claims (7)

a reforming section which generates a reformed gas containing hydrogen by steam reforming a raw fuel gas containing hydrocarbons supplied via a gas meter; a cell stack having a plurality of fuel cell units each having an anode to which the reformed gas generated in the reforming section is supplied and a cathode to which oxygen gas is supplied; a combustion section which combusts a combustion component contained in an anode exhaust gas discharged from the anode; a power conditioner which extracts current from the cell stack and supplies the current to a power line connected to a power system; a raw fuel supplying section which supplies the raw fuel gas to the reforming section; a water supplying section which supplies water to the reforming section; an oxygen supplying section which supplies the oxygen gas to the cathode; and a control device which controls operations of the raw fuel supplying section, the water supplying section, the oxygen supplying section, and the power conditioner, wherein combustion heat generated in the combustion section is utilized for steam reforming by the reforming section, and the raw fuel supplying section, the water supplying section, the oxygen supplying section, and the control device are operable by receiving power supply from at least one of the power system and the cell stack via the power conditioner;
The gas meter is configured to activate an alarm or cut off the supply of the raw fuel gas when a state satisfying a non-leak condition, which indicates that the flow rate of the raw fuel gas is zero or low, does not occur a set number of times during a leakage determination period,
The control device includes:
a leakage determination avoidance process is performed the set number of times or more, the leakage determination avoidance process including a standby process that transitions from a power generation state in which power generation is performed in the cell stack while generating the reformed gas in an amount that the gas meter determines does not satisfy the non-leak condition for at least the amount of the raw fuel gas received by the reforming unit from the gas meter within a specified processing target period having the same length as the leakage determination period, to a standby state in which the gas meter determines that the non-leak condition is satisfied for at least the amount of the raw fuel gas received by the reforming unit from the gas meter, and the standby state continues for a specified standby period that is longer than a set determination period that is a period for the gas meter to determine whether the non-leak condition is satisfied,
a fuel cell system that, if a voltage drop in the grid power is detected by a voltage detection unit that detects the voltage of the grid power supplied from the power grid to the power line while the leakage determination avoidance process is being performed, performs a voltage drop response process to stop the leakage determination avoidance process and transition to the power generation state. The fuel cell system according to claim 1, wherein the control device, during the standby process, sets the amount of the raw fuel gas received by the reforming unit from the gas meter to zero, thereby stopping power generation in the cell stack. The fuel cell system according to claim 1, wherein the control device, during the standby process, receives from the gas meter an amount of the raw fuel gas that the gas meter determines satisfies the non-leak condition in the reforming unit, and generates the reformed gas while generating electricity in the cell stack. an adsorption section having an adsorbent capable of adsorbing the raw fuel gas upstream of the reforming section and a temperature adjustment section capable of adjusting the temperature of the adsorbent;
The fuel cell system according to claim 1 or 3, wherein, during the standby process, the control device controls the temperature of the adsorbent by the temperature control unit, and generates the reformed gas using the raw fuel gas desorbed from the adsorbent, while generating power in the cell stack. an adsorption section having an adsorbent capable of adsorbing the raw fuel gas upstream of the reforming section and a temperature adjustment section capable of adjusting the temperature of the adsorbent;
2. The fuel cell system of claim 1, wherein the control device, during the standby process, sets the amount of the raw fuel gas received by the reforming unit from the gas meter to zero, and generates the reformed gas using the raw fuel gas desorbed from the adsorbent by adjusting the temperature of the adsorbent using the temperature adjustment unit, while generating power in the cell stack. a cell temperature measuring device that measures the temperature of the cell stack, a voltage measuring device that measures the voltage of the cell stack, and a reforming temperature measuring device that measures the temperature of the reforming section,
The control device performs the voltage drop response process when a power generation resumption condition is satisfied, the voltage drop response process including at least one of the following: the temperature of the cell stack is equal to or higher than a set cell temperature, the voltage of the cell stack is equal to or higher than a set cell voltage, and the temperature of the reforming section is equal to or higher than a set reforming temperature, and does not perform the voltage drop response process when the power generation resumption condition is not satisfied. 7. The fuel cell system according to claim 1, further comprising a power storage device capable of supplying power to the power conditioner.

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