JP2002008686A - Controlling method of fuel cell system and its equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a controlling method of a fuel cell system and its equipment solving an adverse effect received in a running of the fuel cell by controlling a reforming equipment supplying reforming gas to the fuel cell, when a power failure occurs to a commercial power source in a system which can supply the electric power of the fuel cell to external loads receiving the supply of electric power from the commercial power source. SOLUTION: When the power failure occurs to a commercial power source supplying electric power to a external loads and when the electric power supply from the fuel cell to external loads is stopped simultaneously, amount of a supply of an original fuel gas to the reforming equipment and its operation can be maintained same as in the state before the electric current being cut off. Thereby, influence to the running of the fuel cell can remarkably lessened at time of recovering electricity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for generating electricity by using hydrogen generated in a reformer, and supplying the generated electric power to an external load which is also supplied with electric power from a commercial power supply. In the fuel cell system configured in
The present invention relates to a method and an apparatus for controlling a fuel cell when a power failure occurs in the commercial power supply.

[0002]

2. Description of the Related Art A polymer electrolyte fuel cell using hydrogen as a fuel gas (hereinafter simply referred to as a fuel cell) has a long life without fear of corrosion by acid or alkali, and has a fuel gas using fossil fuel reformed gas. The ones that have obtained are widely used in cogeneration systems and the like.

[0003]

The reforming device is, for example,
The fuel cell, which is composed of a reformer, a CO (carbon monoxide) converter, a CO remover, etc., supplies hydrogen (fuel gas) using a hydrogen cylinder or a hydrogen storage alloy. There is the problem that the performance of the battery is affected by the reformer as compared to the one that is subjected to it.

[0004] In a fuel cell system connected so that electric power generated by the fuel cell can be supplied to an external load, when a commercial power supply supplying electric power to the external load fails, a breaker is activated. Therefore, the output from the fuel cell to the external load cannot be performed. When the electric output from the fuel cell to the external load becomes zero and the fuel cell is stopped correspondingly, the combustion of the burner of the reformer is stopped, and the devices and burners constituting the cell and the pipes (fuel The gas in the system will be purged with nitrogen, after which all valves will be closed.

[0005] For this reason, once the operation of the fuel cell system is stopped, there is a problem that it takes about 30 minutes to one hour to restart the operation. There is also an idea to shift to the operation mode.

However, in the conventional fuel cell system, since the electric output and the raw fuel supplied to the reformer are interlocked, the electric power to the outside is stopped by a power outage, and at the same time, the electric power is renewed in conjunction with this. The operation is stopped automatically by stopping the raw fuel gas supplied to the quality device or the like, or automatically shifting to a standby operation in which the amount of the raw fuel gas is reduced. Shifting to the standby operation for reducing the amount of raw fuel gas to the reforming apparatus means that all the related equipment, for example, the control valve for controlling the supply of steam and the gas flow, the combustion air and the reaction air, This means that control and adjustment of devices such as a blower for sending or a pump for sending steam or water are also performed in parallel.

[0007] Conversely, after a power recovery from a power failure, it takes time to return the operation of the fuel cell system to a normal stable operation state from such an operation stop or a standby operation.
Even in the standby operation mode, there is a problem that the conventional standby operation cannot cope with a sudden increase in output of the load.

SUMMARY OF THE INVENTION The present invention solves the problems of the prior art, and an object of the present invention is to enable the fuel cell system to return to a normal operation state immediately after a power failure has been completed and power supply to the external load has been restored. It is another object of the present invention to provide a method and an apparatus for controlling a fuel cell system.

Another object of the present invention is to manage a fuel cell system so that standby operation of the fuel cell system during a power outage is not unnecessarily prolonged so that a reasonable operation control of the fuel cell system can be performed. And a control method therefor.

[0010]

According to a first aspect of the present invention, there is provided a method for controlling a fuel cell, comprising a reformer for reforming a raw fuel gas into hydrogen, wherein the reformed gas generated by the reformer is provided. Is supplied to a fuel cell to generate power, and the generated power is supplied to an external load connected to a commercial power supply. The fuel cell is set in a standby operation state while maintaining the function in a stable operation state before the power failure.

Further, the control device for a fuel cell according to claim 2 is
A reformer for reforming the raw fuel gas to hydrogen, supplying the reformed gas generated by the reformer to a fuel cell to generate power, and using the generated power to an external load connected to a commercial power supply In the fuel cell system configured to supply the fuel to the reformer, the reformer is provided with a fuel supply control valve for controlling the supply amount of the raw fuel gas and a burner as a heat source for the reforming reaction. A control valve for controlling the flow of reformed gas supplied to the fuel electrode is provided between the fuel cell and the fuel cell. It is characterized in that it has a device for controlling the amount of reformed gas supplied to the fuel electrode to be reduced to the amount in the standby operation state.

The control device according to claim 3 has a reformer for reforming the raw fuel gas to hydrogen, and supplies the reformed gas generated by the reformer to a fuel cell to generate power. In the fuel cell system configured to supply the generated power to an external load connected to a commercial power supply, the reformer includes a fuel supply control valve for controlling a supply amount of a raw fuel gas and a reforming reaction control valve. A burner as a heat source and a valve for controlling the amount of fuel gas supplied to the burner and the flow rate of off-gas discharged from the fuel electrode are provided. The supply of off-gas to the burner of the reformer is stopped while maintaining the amount of fuel and the amount of reformed gas supplied to the fuel electrode in a stable operation state before a power failure.

The fuel cell control method according to a fourth aspect of the present invention further comprises a reformer for reforming the raw fuel gas into hydrogen, and supplies the reformed gas generated by the reformer to the fuel cell. In a fuel cell configured to generate electric power and supply the generated electric power to an external load connected to a commercial power supply, when the commercial power supply is cut off, the reforming function of the reformer is changed to a stable operation state before the power cut. , The fuel cell is put into a standby operation state, and when the power failure has elapsed for a predetermined time, the reforming function of the reformer and the fuel cell are switched to the standby operation state.

Further, a control device for a fuel cell according to a fifth aspect of the present invention has a reformer for reforming raw fuel gas to hydrogen, and supplies the reformed gas generated by the reformer to the fuel cell. A fuel cell configured to supply the generated power to an external load connected to a commercial power supply.
The reformer has a fuel supply control valve for controlling a supply amount of a raw fuel gas, a burner as a heat source for reforming reaction, and an amount of fuel gas supplied to the burner and a fuel electrode which is discharged from the burner to the burner. While providing a valve for controlling the amount of off-gas supplied, when the commercial power source is out of power, while maintaining the amount of raw fuel supplied to the reformer and the amount of reformed gas supplied to the fuel cell, The supply of off-gas to the burner of the reformer is stopped to switch the fuel of the burner to fuel gas, and when this power outage state has passed for a certain period of time, the amount of raw fuel supplied to the reformer and the fuel cell And a device for controlling the amount of reformed gas supplied to the apparatus to the amount in the standby operation state.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a basic structure of a fuel cell system, wherein reference numeral 3 denotes a reformer constituting a reformer, and 6 denotes a low-temperature operation type operating at 100 ° C. or lower, such as a polymer electrolyte fuel cell. Numeral 12 denotes a burner for heating the reformer 3.

The fuel cell 6 has a fuel electrode 6a, an air electrode 6k, and a cooling section 6c. The fuel electrode 6a is connected to a reformer via a pipe 64, and a high-concentration hydrogen gas (reformed gas) is introduced from the reformer as a fuel gas for a battery, and is used for power generation in the fuel cell 6. Excess hydrogen that has not reacted at the fuel electrode 6a is discharged to the pipe 15 via the control valve 92 as off-gas.

On the other hand, the air electrode 6k is connected to the water tank 21 and the air pump 11 via the pipe line 16, and introduces reaction air as an oxidizing agent and uses it for power generation of the fuel cell 6; Is discharged into the atmosphere via a pipe 27.

A cooling medium such as cooling water is circulated through the cooling section 6c so that the fuel cell 6 is maintained at the operating temperature.

In the reformer 3, the raw fuel gas such as natural gas, city gas, methanol, LPG, and butane sent through the raw fuel pipe 1 and the fuel supply control valve 41 is supplied to the steam source 20.
The pressure is increased by the pressure increasing pump 10 together with the steam supplied from the gas, and supplied to the reformer 3.

The raw fuel gas and steam supplied to the reformer 3 undergo a chemical reaction here, and are reformed into a reformed gas containing hydrogen, carbon dioxide and carbon monoxide. This reformed gas is
Further, the gas is supplied to the fuel electrode 6a of the fuel cell as a gas having a high hydrogen concentration (reformed gas) in which the concentration of carbon monoxide is reduced to 10 ppm or less via a CO converter or a CO remover described later.

In the above configuration, since the reforming reaction in the reformer 3 is an endothermic reaction, the reaction heat is given by heating with the burner 12. Fuel gas is supplied to the burner 12 through the fuel pipe 13 having the combustion control valve 42, off-gas is supplied through the pipe 15 having the off-gas control valve 92, and is supplied by the blower 14 in the burner 12. Combustion of fuel gas and off-gas is performed by the combustion air.

When the fuel cell system is started, the reformer 3
Since the temperature of the fuel cell 6 is low and no off-gas is generated, the burner 12 of the reformer includes the combustion control valve 42 and the fuel pipe 1.
Combustion takes place with the fuel gas supplied via 3.

Thereafter, the temperature of the reformer 3 rises to generate reformed gas. The reformed gas is sent to the fuel cell 6, and when power generation in the fuel cell 6 starts, the fuel cell 6 Temperature can be gradually increased.

In this manner, the reformer and the fuel cell 6
When the temperature of the fuel cell rises to the operating temperature and stabilizes, and the fuel cell system shifts to a steady operation state, off gas is stably discharged from the fuel electrode 6a of the fuel cell.

The control device 95 described later supplies this off-gas to the burner 12 via the pipe line 15 to burn unreacted hydrogen gas in the off-gas and to heat the reformer 3 by the off-gas combustion. Control.

After the fuel cell system shifts to the steady state, the fuel control valve 42 is closed, the supply of fuel gas through the fuel pipe 13 is cut off, and the heating of the reformer 3 by the burner 12 is stopped by the off-gas. By operating the control valve 92, the control is performed only by the off-gas combustion.

The reaction air supplied to the air electrode 6k is sent out to the gas phase 53 by bubbling the reaction air into the water in the water tank 21 by the air pump 11 to be humidified. The reaction air is supplied with water so that the reaction in the fuel cell 6 is appropriately maintained, and then supplied to the air electrode 6k of the fuel cell via the pipe 16.

In the fuel cell 6, the hydrogen in the reformed gas supplied to the fuel electrode 6 a and the air
Electric power is generated by an electrochemical reaction with oxygen in the air supplied to k.

The battery itself generates reaction heat due to activation overvoltage, concentration overvoltage, and resistance overvoltage during the electrochemical reaction,
The temperature required for operating the fuel cell 6 is maintained.

The cooling section 6c of the fuel cell 6 is provided with an electrode 6 of the fuel cell 6 for cooling the fuel cell 6 so that the fuel cell 6 does not overheat due to reaction heat or the like after the fuel cell 6 shifts to a steady operation state.
a, Cooling devices juxtaposed to 6k. The water in the water tank 21 is circulated to the cooling unit 6c by the pump 48, and the cooling water is used to cool the fuel cell 6 so that the temperature inside the fuel cell 6 is maintained at an operating temperature suitable for power generation, for example, 70 ° C to 80 ° C. Is done.

Thus, the fuel cell 6 is controlled so that the temperature inside the cell does not excessively rise due to the heat of reaction, thereby deteriorating the functions of the constituent materials of the cell or damaging the solid polymer membrane of the cell. ing.

In the fuel cell system, the reformed gas generated by the reformer as described above is supplied to the fuel electrode 6 of the fuel cell.
a, and the fuel cell 6 continues a predetermined chemical reaction and power generation.

Next, the startup control of the fuel cell system will be described.

In FIG. 1, reference numeral 95 denotes a control device of the fuel cell system. The control device 95 controls the temperature of the reformer 3 and the fuel cell 6 by the temperature sensor 44 of the reformer 3 and the temperature sensor 45 of the fuel cell 6. While monitoring the temperature of the fuel cell, the fuel and gas flows of the fuel cell system are controlled, and at the same time, the control of supplying the power generated by the fuel cell 6 to the loads 71 and 72 is performed.

A current sensor 49 detects the amount of electric current generated by the fuel cell 6.

The control of the fuel gas by the control device 95 is performed by controlling the fuel supply control valve 41 provided in the raw fuel pipe 1 for the raw fuel gas.
And a combustion control valve 42 provided in the fuel pipe 13, a control valve 93 and an on-off valve 36 provided in pipes 64 and 35 through which reformed gas flows, and a control valve provided in pipes 38 and 15 through which off-gas flows. This is performed by controlling the opening and closing of the valve 40 and the off-gas control valve 92.

When the fuel cell system having such a configuration is started, the temperature is low and the reforming reaction is not sufficient. Therefore, the control device 95 determines that the temperature of each reactor such as the reformer 3 has reached the operating temperature and stabilized. Until the reformed gas having the composition is generated, the control valve 93 is closed and the on-off valve 36 is opened.

As a result, the reformed gas having an unstable composition is not supplied to the fuel cell 6 but is supplied to the PG burner 34 via the pipe 35.
It is led and burned here.

After activating the reformer of the fuel cell system and stabilizing the temperature and operation of each reactor including the reformer 3, the controller 95 closes the on-off valve 36 and opens the control valve 93, The reformed gas is supplied to the fuel electrode 6a of the fuel cell to start power generation in the fuel cell system.

The fuel electrode 6a into which the reformed gas has been introduced also has a low battery temperature at the beginning and hardly generates power, and even when power generation is started, it does not immediately enter the rated stable operation state.

While the temperature of the fuel cell 6 is low and the power generation is slight, the control device 95 controls the DC / DC converter 107 and the system-linked inverter 108 to apply a load corresponding to the power generation capacity of the fuel cell 6. In addition, control is performed so that the temperature of the fuel cell rises (load temperature rise) due to the heat generated by the cell itself.

That is, when the power generation by the fuel cell 6 is started and its open voltage is confirmed, the control device 95
Immediately, the open voltage is connected to the electric power system via the inverter 108, and the electric load is started to be applied to the fuel cell 6 while the power generation capacity is small.

In this process, the control device 95 monitors the temperature of the fuel cell 6 with the temperature sensor 45, and gradually increases the electric load to the fuel cell 6 in a manner to increase the take-out current value according to the battery temperature at that time. Increase the fuel cell 6
The self-reaction heat is used to raise the temperature of the cell to the rated stable operation state as soon as possible, so that the operation of the fuel cell can be promptly shifted to the steady operation state.

The unreacted gas not used for power generation in the fuel cell 6 is supplied to a PG burner 34 via a pipe 38 and a control valve 40.
And is burned here.

After the temperature of the fuel cell 6 rises due to an increase in the load and stabilizes near the operating temperature (for example, 70 ° C. to 80 ° C.), and reaches the rated output state, the off-gas discharged from the fuel electrode 6a is reduced. The composition also becomes stable. The control device 95
By closing the control valve 40 and opening the off-gas control valve 92, the off-gas flow is switched from the line 38 to the line 15,
Control is performed so that off-gas can be burned by the burner 12 of the reformer.

In this way, after the fuel cell system reaches the rated stable operation state, the burner 12 of the reformer
An unreacted gas (hydrogen) in the off-gas introduced via the pipe 15 is burned to enter a steady operation state in which heating of the reformer 3 is continued.

In the pipes 15, 64, 35, and 38 in the steady operation state of the fuel cell system, the control valves 92 and 93 are open and the valves 36 and 40 are closed.

Thus, in the fuel cell system,
The temperature of the fuel cell 6 is reduced to the operating temperature (70
(° C. to 80 ° C.) so that rated power generation can be continuously performed.

In this state, most of the energy of the reformed gas is used for power generation, and the obtained electric power is controlled by the DC / DC converter 107 and the system-coupling inverter 108 so that the supplied electric energy is equal to the rated load (for example, AC). The power is supplied to the load 72 connected to the fuel cell system while being controlled to fall within 1 kW).

The load includes an electric device (hereinafter referred to as a system load 71) such as an auxiliary device constituting the fuel cell system, such as a water pump or a blower, a control valve or an on-off valve, or a controller.
) And private loads (hereinafter, private loads 72) such as household lighting fixtures and electric appliances equipped with fuel cells.
Power is supplied to these loads 71 and 72 in accordance with the power generation capacity of the fuel cell system.

The relationship between the amount of current (electric power) obtained from the fuel cell system and the amount of raw fuel gas supplied to the fuel cell system via the pipe 1 is, for example, as shown in FIG. The amount of raw fuel gas for reforming (the amount of raw fuel gas supplied to the reformer 3) is in a substantially proportional relationship.

FIG. 2 shows the correlation when the utilization rate of hydrogen gas used for power generation in a fuel cell is regulated at a constant rate (for example, about 70%), and the remainder is discharged as off-gas. ing.

FIG. 2 shows that if the amount of raw fuel gas supplied to the reformer is increased or decreased, the generated power (cell current value) of the fuel cell system can be increased or decreased in proportion.

[0055] Ancillary equipment constituting the fuel cell system, for example, a pump or a blower, a control valve or an on-off valve, or
Although power is supplied to the controller and the like (system load) from the commercial power supply when the system is started, the power supply from the fuel cell is performed after the fuel cell 6 enters the rated stable operation state. To be operated independently of the commercial power supply.

Also, it is necessary to increase or decrease the amount of power generated by the fuel cell 6 by supplying power generated by the fuel cell system to the private load 72 or increasing or decreasing the amount of electric load supplied to the private load 72. At this time, the control device 95 detects this change with the current sensor 49 and controls the inverter 108 such that the reverse power flow to the system becomes zero, and at the same time, for example, increases and decreases as described in FIG. The amount of the reformed gas supplied to the fuel electrode 6a is controlled to increase or decrease according to the amount of load power to be performed.

The control unit 95 calculates and calculates the amount of the raw fuel gas supplied to the reformer 3 in order to supply the reformed gas corresponding to the load power to the fuel electrode 6a. While increasing the opening of the supply control valve 41, the amount of steam supplied to the reformer 3 is also increased. Thus, the fuel electrode 6a of the fuel cell can generate electric power corresponding to the increase in the electric load.

Although not specifically shown in FIG. 1, the blowers 14 and 37 provided in the burner 12 and the PG burner 34 are respectively provided with the burners 12 and 34.
The amount of air corresponding to the amount of gas supplied to the burner is supplied to the burner and burned. Control valve 40, combustion control valve 4
2. The on / off control of the off-gas control valve 92 and the like is performed, for example, by opening the control valve 40 provided in the pipe 38, the combustion control valve 42 provided in the pipe 13 and the off-gas control valve 92 provided in the pipe 15. It is preferable to control the temperature of the reformer 3 at a constant operating temperature so as not to disturb the temperature of the reformer 3 at all times.

The burner 12 of the reformer is supplied with the off-gas via the off-gas control valve 92 and the fuel gas via the combustion control valve 42 at the same time and burns, and the fuel cell system reaches the rated stable operation state. Later, the combustion control valve 42 may be closed to switch to combustion using only off-gas.

Further, even after the fuel cell system has reached the rated stable operation state, the line 38 and the control valve 40
The extra off-gas may be guided to the PG burner 34 via the PG burner 34 and burned to stabilize the temperature of the reformer 3.

Next, a description will be given of control when a power failure occurs in the commercial power supply to which an external load is connected after the fuel cell system has reached the rated stable operation state.

When a power failure occurs in the commercial power supply on the external load side to which the fuel cell system is connected, first, a switch (not shown) that has detected the power failure is operated from the fuel cell system to the private load 72. Stop the power supply once.

On the other hand, in a fuel cell system in which power is supplied from a commercial power supply to the system load 71, a switch is operated so that power can be supplied from the fuel cell so that power supply is not interrupted by a power failure. . On the other hand, after the fuel cell system enters the steady state, the system load is reduced.
In the fuel cell system in which the power supply to the fuel cell 1 is performed from the fuel cell 6, control is performed so that the power supply from the fuel cell 6 can be continuously received, thereby hindering the operation of the fuel cell system and the devices constituting the system. The controller 95 operates so as not to occur.

At this time, on the reformer side constituting the fuel cell system, even if there is a power failure of the commercial power supply system,
The reforming function is controlled so as to be maintained at the state of the reformed gas generation capacity before the power failure, and the fuel cell 6 side is controlled so as to be in a standby state of low power generation capacity without supplying power to an external load. You.

For this reason, the control of the reformer and the related equipment constituting the fuel cell system is controlled in the same manner as before the power failure. Fuel gas is supplied to the burner 12 of the reformer 3 through the combustion control valve 42 and the fuel pipe 13 so that the temperature of the reformer 3 is maintained as it was before the power failure. The raw fuel supply control valve 41 for supplying the gas is maintained at the opening before the power failure, and the steam source 20 is supplied with steam corresponding to the reforming reaction of the raw fuel gas, and the same amount of reforming as before the power failure is performed. Gas continues to be supplied to line 64.

The control of the fuel cell 6 and the related devices constituting the fuel cell system is performed by opening the on-off valve 36 and burning most of the reformed gas by the PG burner 34 while controlling the control valve 9.
The amount of the reformed gas supplied to the fuel electrode 6a of the fuel cell by changing the opening degree of the fuel cell 3 is changed to the amount of the standby operation state, in other words, the fuel cell 6 is adapted to supply the power generation capacity to the system load 71. The standby operation is controlled so that the power generation capacity is reduced so that the power generation capacity is maintained.

Further, the off-gas control valve 92 is closed and the control valve 40 is opened to control so that all the off-gas discharged from the fuel electrode 6 a is burned in the PG burner 34.

The control of the reformed gas supplied to the fuel electrode 6a is not limited to this. For example, while the on-off valve 36 is closed,
All the reformed gas generated by the reformer is supplied to the fuel electrode 6a via the control valve 93, and all the reformed gas not used in the fuel cell 6 is supplied to the PG burner via the control valve 40 and the pipe 38. It may be controlled so as to flow and burn.

Thus, for example, after a power failure in the commercial power supply system, the fuel cell system can maintain the reformed gas generation function of the reformer in the operating state before the power failure in a stable manner. Only 6 is controlled to a standby operation state in which power is supplied to the system load 71 so that the output of the inverter 108 becomes zero.

In the above description, the burner 1 of the reformer is used.
The fuel of No. 2 was entirely covered by the fuel gas from the fuel pipe 13.
If the control of the combustion control valve 42 can be performed precisely, a part of the off-gas from the fuel cell 6 can be caused to flow to the burner 12 so that the temperature of the reformer 3 is maintained at a temperature in a steady operation state. .

In this way, while maintaining the reforming function of the reformer in the stable operation state before the power failure, the fuel cell 6
When the state in which the fuel cell is kept in the standby operation continues for a predetermined time, for example, 10 minutes or 30 minutes or more, the control device 95 detects the lapse of time by a timer (not shown), and sends the raw fuel to the reformer 3. The opening degree of the fuel supply control valve 41 for supplying gas may be reduced.

The opening of the fuel supply control valve 41 in this case is
When the system load 71 and the private load 72 are supplying power to the system load 71 and the system load 71 is supplying power only to the system load 71, the opening degree of the raw fuel gas is changed according to the load amount. The opening is limited to such a degree as to be supplied to the porcelain container 3.

As a result, the raw fuel gas supplied to the reformer 3 only generates the reformed gas necessary for the fuel cell 6 to supply power to the system load 71 or the system load 71 and the private load 72. The fuel cell system is limited to the amount of the raw fuel gas, and the fuel cell system can be substantially switched to the standby operation state as in the related art.

In the above embodiment, a polymer electrolyte fuel cell has been mainly described as a fuel cell. However, in a fuel cell to which the present invention can be applied, a reformer is used for the fuel gas (hydrogen) of the fuel cell. Other batteries,
For example, it can be used for batteries such as PAFC (phosphoric acid electrolyte type) and AFC (alkaline aqueous solution electrolyte type).

In such a fuel cell system, even when a power failure occurs in a commercial power supply that supplies power to an external load to which the fuel cell is connected, the output to the external load is lost, Without changing the amount of raw fuel gas supplied to the reactor, the flow is the same as before the power outage, and the operation of the reformer is maintained in the same operating state as before the power outage. When power is restored in minutes, power supply from the fuel cell can be started immediately, and power is supplied to the fuel cell system and the load supplied from the system almost without being substantially affected by a short-time power outage. Can be resumed.

In the present invention, the supply of the raw fuel gas to the reformer is continued even during a power outage, and the reformed gas is controlled to be burned by the PG burner. In the case of, the fuel cell system is stopped and purged, and when the operation is resumed, compared to a method in which the reformer is preheated again, overall, it is rather energy saving,
The fuel cell system can be operated reasonably.

FIG. 3 shows such a fuel cell system.
FIG. 7 is a diagram showing an embodiment used in a small-sized integrated energy system for home use that incorporates a polymer electrolyte fuel cell such as a polymer electrolite fuel cell so that electric power and hot water can be supplied to the outside. is there.

In FIG. 3, the same devices as those in FIG.
Parts are given the same numbers and their explanation is omitted.

The total energy system of this embodiment is as follows:
As described later, a heat recovery device RD is included in addition to the power generation system GS using the fuel cell 6.

The electric power generated by the fuel cell 6 of the fuel cell power generation system GS is supplied to the system load 71, is boosted up to 180 V through the DC / DC converter 107, and is passed through the system interconnection inverter 108. , A lighting device, a television, or the like.

The heat recovery unit RD is connected to a hot water storage tank 50, heat exchangers 32 and 46, and water circulation paths provided with pumps 33 and 47, and the like.

In such a total energy system using the fuel cell 6, city water is supplied into the hot water storage tank 50 through a water supply pipe 61 connected to the hot water storage tank 50.
The city water supplied to the hot water storage tank 50 is heated, for example, by heating the heat generated in the process of power generation by the fuel cell 6 or the gas generated in the power generation system GS and heating it. The fuel used in the fuel cell 6 can be effectively used, for example, by heating the water, storing the heated warm water in the hot water storage tank 50, and supplying the hot water to the bath or kitchen via the hot water supply pipe 62. Make it available.

In FIG. 3, raw fuel gas is supplied to the reformer 3 by supplying raw fuel gas such as natural gas, city gas, methanol, LPG, butane, etc., to the desulfurizer 2 via the fuel pipe 1. The sulfur component is removed from the raw fuel gas. The raw fuel gas that has passed through the desulfurizer 2 is pressurized by the pressurizing pump 10 and supplied to the reformer 3.

The exhaust system 31 of the reformer 3 has a heat exchanger 17
When the water in the water tank 21 is supplied to the heat exchanger 17 through the pump 22, the heat exchanger 1
At 7 the steam is formed. That is, the heat exchanger 17 functions as a steam source 20 for the reformer 3, and the steam is mixed with the raw fuel gas passed through the desulfurizer 2 and the pump 10 and supplied to the reformer 3. Is done.

The raw fuel gas supplied to the reformer 3 is
Here, a chemical reaction occurs, and a reformed gas containing hydrogen, carbon dioxide, and carbon monoxide is generated. This reformed gas is supplied to the CO converter 4, where carbon monoxide contained in the fuel gas is converted into carbon dioxide. The gas that has passed through the CO converter 4 is supplied to a CO remover 5, where unconverted carbon monoxide in the gas that has passed through the CO converter 4 is oxidized to carbon dioxide. Through the CO remover 5, a gas with a high hydrogen concentration (reformed gas) in which the concentration of carbon monoxide has been reduced to 10 ppm or less is supplied to the fuel electrode 6a of the polymer electrolyte fuel cell 6.

At this time, the amount of steam added to the reformed gas is adjusted by adjusting the amount of treated water supplied from the water tank 21 to the reformer 3 by the pump 22.
For example, the ratio (S / C ratio) between the amount of steam supplied to the reformer 3 via the heat exchanger 17 and the amount of the raw fuel gas is calculated from the value of 2 to 3 which is the conventional S / C ratio. Is also higher, for example,
If the S / C ratio is set to 3 or 4, the reformer 3
Can be increased in the amount of water contained in the reformed gas that has exited.

The fuel gas that has exited the CO remover 5 may be supplied directly to the fuel cell 6, but the fuel gas which remains at a high temperature flows into the fuel electrode 6a, and the temperature of the fuel cell 6 becomes too high. When there is a possibility that the power generation function may be reduced or the electrodes of the battery may be damaged, a heat exchanger (not shown) is provided in a pipe 64 between the CO remover 5 and the fuel cell 6, and this heat exchange is performed. The water in the water tank 21 is passed through the vessel to exchange heat with the reformed gas, thereby controlling the temperature of the reformed gas.

Further, when the S / C ratio is increased, the reformed gas supplied to the fuel electrode 6a of the fuel cell has an appropriate moisture content without a separate humidifier for humidifying the reformed gas. Can be given.

When the integrated energy system is started, as described above, the fuel gas and the combustion air are supplied to the burner 12 to perform combustion. After the start, the reformer 3 and the fuel cell 6 are stabilized at the operating temperature. At times, the supply of the fuel gas from the fuel pipe 13 is cut off, and the off-gas discharged from the fuel electrode 6a is supplied as fuel through the pipe 15 instead, and the combustion in the burner 12 is continued.

Since the chemical reaction performed in the CO converter 4 and the CO remover 5 is an exothermic reaction, for example, in the CO remover 5, a burner (not shown) is used only when the fuel cell system is started.
Is burned to generate a combustion gas, and the heat of the combustion gas generated at this time raises the temperature of the CO remover 5 to the reaction temperature, and thereafter, the reaction temperature is maintained by the heat of the exothermic reaction of itself.

Cooling control is performed from the outside so that the temperature of the CO converter 4 and the CO remover 5 does not rise above the reaction temperature, if necessary.

In the fuel cell 6, the hydrogen in the reformed gas supplied to the fuel electrode 6a and the oxygen in the air supplied to the air electrode 6k via the air pump 11 and the gas phase 53 of the water tank are mixed. While electric power is generated by the electrochemical reaction, the battery itself generates reaction heat and rises in temperature due to the electrochemical reaction.

In the cooling section 6c of the fuel cell 6, the water in the water tank 21 is circulated by the pump 48 as cooling water in the same manner as in FIG. 1, so that the temperature in the fuel cell 6 is maintained at a temperature suitable for power generation. Cooling control.

A heat exchanger 1 is provided between the reformer 3 and the CO converter 4 and between the CO converter 4 and the CO remover 5, respectively.
8 and 19 are connected, and water is circulated from the water tank 21 to the heat exchangers 18 and 19 via pumps 23 and 24,
The gas that has passed through the reformer 3 and the CO converter 4 is cooled.

In this way, the reformer 3, the CO shift converter 4,
In the CO remover 5 and the fuel cell 6, a predetermined chemical reaction (reforming reaction) and power generation are continued.

After the temperatures of the reformer 3 and the fuel cell 6 are stabilized at the operating temperature and the rated power generation is continuously performed (rated stable operation state), the reforming supplied to the fuel electrode 6a is performed. Most of the gas is used for power generation, and the obtained electric power is supplied to loads such as electric devices via the DC / DC converter 107 as described above.

The control device 95 shown in FIG. 3 controls the electric power generated by the fuel cell 6 and controls the temperature rise of the load. After the fuel cell 6 is started, the temperature of the reformer 3 becomes stable and constant. Until a reformed gas having the following composition is obtained, the reformed gas having an unstable gas composition generated in the fuel cell 6 is burned by the PG burner 34, and the heat load connected to the burner 34, for example, the hot water storage tank 50 Is controlled so that heat energy is recovered.

When a reformed gas having a predetermined quality can be obtained from the reforming device including the reformer 3 and the CO remover 5, the controller 95 sends the reformed gas to the fuel electrode of the fuel cell. 6
a, and while the exhaust gas is burned by the PG burner 34, the take-out current is gradually increased and the load of the fuel cell is raised.

When the fuel cell 6 reaches the rated stable operation state, the control device 95 controls to switch the flow of the off-gas discharged from the fuel electrode 6a to the heating burner 12 side of the reformer.

On the other hand, during operation of the integrated energy system in the rated stable operation state in this way, a power failure occurs in the commercial power supply on the external load side to which the fuel cell used in the system is connected, and When the output from the battery to the external load stops, the control device, as described with reference to FIG. 1, does not change the amount of the raw fuel gas supplied to the reforming device, but supplies the same amount of raw fuel gas as before the power failure. The gas is passed to keep the operation of the reformer in the same operating state as before the power failure.

In the case of a commercial power supply that supplies power to a home or the like in which a small integrated energy system is used, even in the case of a power failure, power is often restored in a matter of seconds or minutes in most cases. In such a case, the power supply from the fuel cell can be restarted immediately, and the power supply to the integrated energy system and the load supplied from the system can be restarted almost without being substantially affected by the short-time power failure. Can be.

In the total energy system using the control method of the fuel cell system of the present invention, not only energy before power generation is started but also energy not used for power generation at the time of power failure or unused fuel gas is used. The burner burns the hot water and recovers it as hot energy in hot water, so that the loss can be reduced in terms of energy efficiency, and the system can be operated in standby mode during a power outage. It is possible to provide a cogeneration system having a large power generation and heat utilization effect that leads to further effective utilization of the energy of the raw fuel gas supplied to the fuel cell.

[0103]

According to the present invention, in a fuel cell system configured to supply electric power generated by a fuel cell having a reformer to an external load connected to a commercial power supply, when the commercial power supply fails, Since the fuel cell is set to the standby operation state while maintaining the reforming function of the reforming device in the operation state before the power failure, when the power supply from the fuel cell stops due to a power failure on the external load side. However, substantially, the operation of the fuel cell system can be continued in the same manner as before the power outage, and the fuel cell can immediately return to the normal operation state after the power is restored.

If such control continues for a certain period of time or more, a timer is used to detect the lapse of time and reduce the opening of the fuel supply control valve that supplies the raw fuel gas to the reformer. As a result, it is possible to provide a fuel cell system with improved convenience and energy efficiency of the fuel cell system.

[Brief description of the drawings]

FIG. 1 is a diagram showing a basic configuration of a fuel cell system having a control device according to the present invention.

FIG. 2 is a diagram showing a relationship between a current value generated by a fuel cell and a raw fuel gas amount for reforming.

FIG. 3 is a diagram showing an embodiment of a total energy system having a control device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Raw fuel tube 3 Reformer 6 Fuel cell 6a Fuel electrode 6k Air electrode 12 Burner for heating reformer 13, 15, 35, 38 Pipeline 20 Steam source 34 PG burner 36 Open / close valve 40, 93 Control valve 41 Fuel Supply control valve 42 Combustion control valve 44, 45 Temperature sensor 49 Current sensor 71 System load 72 Private load 92 Offgas control valve 95 Controller 107 DC / DC converter 108 Grid-connected inverter GS Power generation system RD Heat recovery device

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Kazuhiro Tajima 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Satoshi Yamamoto 2-5-2 Keihanhondori, Moriguchi-shi, Osaka No. 5 Sanyo Electric Co., Ltd. (72) Inventor Akira Fujio 2-5-5 Keihan Hondori, Moriguchi-shi, Osaka Pref. Sanyo Electric Co., Ltd. (72) Inventor Taketoshi Koki Keihanhondori, Moriguchi-shi, Osaka 2-5-5 Sanyo Electric Co., Ltd. (72) Inventor Katsuyuki Makihara 2-5-5 Keihanhondori, Moriguchi-shi, Osaka F-term in Sanyo Electric Co., Ltd. 5H026 AA06 5H027 AA06 DD01 MM08 MM09 MM12

Claims (5)

[Claims] 1. A reformer for reforming a raw fuel gas into hydrogen, supplying a reformed gas generated by the reformer to a fuel cell to generate electric power, and using the generated electric power as a commercial power supply In the fuel cell system configured to supply an external load connected to the fuel cell, when the commercial power source is in a power failure, the fuel cell is in standby operation while the reforming function of the reformer is maintained in a stable operation state before the power failure. A method for controlling a fuel cell system, comprising: 2. A reforming apparatus for reforming raw fuel gas into hydrogen, supplying the reformed gas generated by the reforming apparatus to a fuel cell to generate electric power, and using the generated electric power as a commercial power supply In a fuel cell system configured to supply to an external load connected to the fuel cell system, the reformer is provided with a fuel supply control valve for controlling a supply amount of raw fuel gas and a burner as a heat source for reforming reaction, A control valve for controlling the flow of reformed gas supplied to the fuel electrode was provided between the reformer and the fuel cell, and when the commercial power supply was out of power, the opening of the fuel supply control valve was maintained. A control device for a fuel cell system, further comprising a control device for controlling an amount of reformed gas supplied to a fuel electrode of a fuel cell to an amount in a standby operation state. 3. A reformer for reforming raw fuel gas to hydrogen, supplying the reformed gas generated by the reformer to a fuel cell to generate electric power, and using the generated electric power as a commercial power supply In the fuel cell system configured to supply an external load connected to the fuel cell, the reformer includes a fuel supply control valve for controlling a supply amount of the raw fuel gas, a burner as a heat source for a reforming reaction, and a burner as a heat source for the reforming reaction. A valve for controlling the amount of supplied fuel gas and the flow rate of off-gas discharged from the fuel electrode is provided, and when the commercial power source is out of power, the amount of raw fuel supplied to the reformer and the fuel electrode A control device for a fuel cell, wherein the supply of off-gas to a burner of the reformer is stopped while the amount of supplied reformed gas is maintained in a stable operation state before a power failure. 4. A reformer for reforming raw fuel gas to hydrogen, supplying the reformed gas generated by the reformer to a fuel cell to generate electric power, and using the generated electric power as a commercial power supply In the fuel cell configured to be able to supply to an external load connected to the fuel cell, when the commercial power supply fails, the fuel cell is kept in a standby operation state while the reforming function of the reformer is maintained in a stable operation state before the power failure. And switching the reforming function of the reformer and the fuel cell to a standby operation state when a predetermined time has elapsed after the power failure. 5. A reformer for reforming raw fuel gas to hydrogen, supplying the reformed gas generated by the reformer to a fuel cell to generate electric power, and using the generated electric power as a commercial power supply A fuel supply control valve for controlling a supply amount of a raw fuel gas, a burner as a heat source for a reforming reaction, and a fuel supply control valve for controlling a supply amount of the raw fuel gas. A valve for controlling the amount of fuel gas to be supplied and the amount of off gas discharged from the fuel electrode and supplied to the burner is provided, and when the commercial power supply is out of power,
While maintaining the supply amount of the raw fuel to the reformer and the amount of the reformed gas supplied to the fuel cell, the supply of the off gas to the burner of the reformer was stopped to reduce the fuel of the burner to the fuel gas. And a device for reducing the amount of the raw fuel supplied to the reformer and the amount of the reformed gas supplied to the fuel cell to the standby operation state amount when the power outage state has elapsed for a predetermined time. A control device for a fuel cell, comprising: