JP2018206509A - Fuel cell system and operation method thereof - Google Patents

Abstract

To keep the inside of a stopped fuel cell stack at a positive pressure for the atmospheric pressure, without increasing power consumption, in a system for generating power from appropriate number of fuel cell stacks according to the power generation amount.SOLUTION: A fuel cell system 100 includes multiple fuel cell stacks 1-1 through 1-N performing power generation by using fuel gas containing hydrogen and oxidant gas, a fuel gas supply path 2 for supplying fuel gas, and a control section 3. The control section 3 controls to generate power by changing the number of the multiple fuel cell stacks 1-1 through 1-N to be operated according to a target power generation amount, to supply fuel gas to the stopped fuel cell stacks 1-1 through 1-N, to stop discharge of unreacted fuel gas therefrom, thus keeping the inside of a stopped fuel cell stacks 1-1 through 1-N at a positive pressure for the atmospheric pressure. With such a configuration, power consumption for keeping the inside of the fuel cell stacks 1-1 through 1-N at a positive pressure for the atmospheric pressure can be reduced, and generation efficiency of the fuel cell system 100 can be improved.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fuel cell system that generates power by supplying fuel gas to a plurality of fuel cell stacks.

  Conventionally, in this type of fuel cell system, an electrolyte layer is sandwiched between a fuel electrode (anode) and an air electrode (cathode) to form a cell, fuel gas containing hydrogen as fuel, and air containing oxygen in the air electrode. When supplied, electric energy is obtained by an electrochemical reaction. Since the generated voltage obtained by one unit cell is often less than 1 V, a practical fuel cell obtains a high voltage by stacking unit cells.

  In recent years, fuel cell systems have come to be used not only for general home use but also for in-vehicle use and business use. For in-vehicle use and business use, the capacity of power generation is larger than that for general home use fuel cell systems. It has been demanded.

  In order to realize a large amount of power generation, fuel gas supply pipes are connected so that a plurality of fuel cell stacks have a parallel configuration, and a necessary power generation amount is secured (for example, see Patent Document 1). .

  In addition, when generating and stopping a plurality of fuel cell stacks, a valve (provided periodically in the fuel gas supply path upstream of the fuel cell stack to prevent outside air from being mixed into the fuel cell stack in a power generation stop state ( Hereinafter, the fuel supply valve is opened and closed, and fuel gas is supplied into the fuel cell stack so as to be positive with respect to the atmospheric pressure. This control prevents the fuel cell stack pressure from becoming negative relative to the atmospheric pressure, and ensures that the fuel cell stack is reliable by preventing air from entering the fuel cell stack. (For example, refer to Patent Document 2).

JP 2012-18823 A JP 2014-7169 A

  However, the conventional configuration has a problem that the durability of the fuel supply valve is deteriorated due to opening and closing of the fuel supply valve. In addition, when generating power using multiple fuel cell stacks in order to support a large capacity power generation capacity, the pressure in the fuel cell stack becomes higher than the atmospheric pressure as the number of fuel cell stacks in the power generation stop state increases. Therefore, the number of fuel supply valves increases to maintain a positive pressure. For this reason, the fuel cell system as a whole has a problem that the number of times of opening and closing the fuel supply valve is increased, and power consumption for operating the fuel supply valve is increased.

  The present invention solves the above-described conventional problems, and provides a fuel supply by providing a system comprising a plurality of fuel cell stacks capable of supplying fuel gas to a stopped fuel cell stack via a fuel gas supply path. An object of the present invention is to provide a fuel cell system that can maintain a fuel cell stack in a power generation stopped state at a positive pressure with respect to atmospheric pressure without using a valve.

  In order to solve the above-described conventional problems, a fuel cell system according to the present invention includes a plurality of fuel cell stacks that generate power using a fuel gas containing hydrogen and an oxidant gas, and a fuel gas supply path for supplying the fuel gas. And a control unit, wherein the control unit generates power by changing the number of operating fuel cell stacks according to the target power generation amount, supplies fuel gas to the stopped fuel cell stack, and the fuel cell stack The discharge of unreacted fuel gas from the fuel cell is closed, and the stopped fuel cell stack is made positive with respect to the atmospheric pressure.

  As a result, when power is generated by changing the number of operating fuel cell stacks according to the amount of power generated, the fuel cell stack is stopped without opening and closing the fuel supply valves. The multiple fuel cell stacks can be made positive with respect to the atmospheric pressure, the multiple fuel supply valves can be reduced, the problem of durability deterioration of the fuel supply valves can be solved, and the fuel supply valves can be opened and closed It becomes possible to reduce the power consumption.

  The fuel cell system of the present invention includes a plurality of fuel cell stacks that generate power using a fuel gas containing hydrogen and an oxidant gas, a fuel gas supply path that supplies fuel gas to the plurality of fuel cell stacks, A plurality of unreacted fuel gas circulation paths for joining unreacted fuel gas discharged from each of the plurality of fuel cell stacks to respective fuel gas supply paths of the plurality of fuel cell stacks; and a plurality of unreacted fuel gas circulation paths A plurality of unreacted fuel gas circulation means provided in each, and a control unit, wherein the control unit generates power by changing the number of operating fuel cell stacks according to the target power generation amount, and stops the fuel Fuel gas is supplied to the battery stack, and the inside of the stopped fuel cell stack and the inside of the unreacted fuel gas circulation path are made positive with respect to the atmospheric pressure.

  As a result, when generating power by changing the number of operating fuel cell stacks according to the amount of power generation, from the viewpoint of safety, a fuel gas supply path, a plurality of fuel cell stacks, a plurality of unreacted fuel gas circulation paths (hereinafter referred to as the above) In order to prevent air from being mixed into hydrogen in the anode path), the fuel cell system is designed so that the anode path has a positive pressure with respect to the atmospheric pressure. In order for the anode path to have a positive pressure with respect to the atmospheric pressure, the unreacted fuel gas is designed to have a positive pressure with respect to the atmospheric pressure. As a result, the plurality of fuel cell stacks and the unreacted fuel gas circulation path can be made positive with respect to the atmospheric pressure without opening and closing the plurality of fuel supply valves. It is possible to reduce supply valves and reduce power consumption for opening and closing the fuel supply valves.

  The fuel cell system of the present invention can maintain the pressure in the fuel cell stack in the power generation stopped state at a positive pressure with respect to the atmospheric pressure without opening and closing the fuel supply valve. It becomes possible to reduce. Thereby, the power consumption for opening and closing the fuel supply valve can be reduced, and the power generation efficiency of the fuel cell system can be improved. Furthermore, since the problem of durability deterioration due to an increase in the number of opening and closing of the fuel supply valve can be solved, the durability of the fuel cell system can be improved. Moreover, the cost of the fuel cell system can be reduced by reducing the fuel supply valves.

1 is a block diagram of a fuel cell system according to Embodiment 1 of the present invention. Block diagram of a fuel cell system according to Embodiment 2 of the present invention

A first invention includes a plurality of fuel cell stacks that generate electric power using a fuel gas containing hydrogen and an oxidant gas, a fuel gas supply path for supplying fuel gas, and a control unit. , Generating power by changing the number of operating fuel cell stacks according to the target power generation amount, supplying fuel gas to the stopped fuel cell stack, and closing discharge of unreacted fuel gas from the fuel cell stack, By making the inside of the stopped fuel cell stack a positive pressure with respect to the atmospheric pressure, it becomes possible to reduce the fuel supply valve for making the inside of the fuel cell stack a positive pressure with respect to the atmospheric pressure. The power consumption for opening and closing can be reduced, and the power generation efficiency of the fuel cell system can be improved.

  A second invention includes a plurality of fuel cell stacks that generate power using a fuel gas containing hydrogen and an oxidant gas, a fuel gas supply path for supplying fuel gas to the plurality of fuel cell stacks, and a plurality of fuel cells. The unreacted fuel gas discharged from each of the stacks is provided in each of a plurality of unreacted fuel gas circulation paths for joining the respective fuel gas supply paths of the plurality of fuel cell stacks and a plurality of unreacted fuel gas circulation paths. A plurality of unreacted fuel gas circulation means and a control unit. The control unit generates power by changing the number of operating fuel cell stacks according to the target power generation amount, and supplies fuel to the stopped fuel cell stack. By supplying gas and making the inside of the stopped fuel cell stack and the unreacted fuel gas circulation path positive with respect to the atmospheric pressure, the inside of the fuel cell stack and unreacted It is possible to reduce the fuel supply valve for making the inside of the gas gas circulation path positive with respect to the atmospheric pressure, reduce the power consumption for opening and closing the fuel supply valve, and Efficiency can be improved.

  According to a third aspect of the invention, in particular, in the fuel cell system of the second aspect of the invention, the controller is configured to control the plurality of unreacted fuel gas circulation means that are operating based on the respective power generation amounts of the plurality of operating fuel cell stacks. By controlling the flow rate of the unreacted fuel gas supplied to the fuel cell stack, it is possible to discharge the excess fuel gas from the downstream of the fuel cell stack and control the flow rate as the unreacted fuel gas. As a result, it is possible to supply more fuel gas than the fuel gas necessary for power generation to the fuel cell stack that is generating power, preventing voltage drop of the fuel cell stack, and stable power generation of the fuel cell system. Can be realized.

  According to a fourth aspect of the invention, there is provided a method of operating a fuel cell system including a plurality of fuel cell stacks that generate power using a fuel gas containing hydrogen and an oxidant gas, and a fuel gas supply path for supplying the fuel gas. A step of generating power by changing the number of operating fuel cell stacks according to the target power generation amount, supplying fuel gas to the stopped fuel cell stack, and closing discharge of unreacted fuel gas from the fuel cell stack By executing the step of making the inside of the stopped fuel cell stack positive with respect to the atmospheric pressure, the fuel supply valve for making the inside of the fuel cell stack positive with respect to the atmospheric pressure can be reduced. Thus, power consumption for opening and closing the fuel supply valve can be reduced, and the power generation efficiency of the fuel cell system can be improved.

  In the fifth invention, a plurality of fuel cell stacks for generating power using a fuel gas containing hydrogen and an oxidant gas, a fuel gas supply path for supplying fuel gas to the plurality of fuel cell stacks, and a plurality of fuel cells The unreacted fuel gas discharged from each of the stacks is provided in each of a plurality of unreacted fuel gas circulation paths for joining the respective fuel gas supply paths of the plurality of fuel cell stacks and a plurality of unreacted fuel gas circulation paths. A method of operating a fuel cell system including a plurality of unreacted fuel gas circulation means, generating a power by changing the number of operating fuel cell stacks according to a target power generation amount, and stopping the fuel cell stack. Supplying a fuel gas and setting the inside of the stopped fuel cell stack and the unreacted fuel gas circulation path to a positive pressure with respect to the atmospheric pressure. This makes it possible to reduce the fuel supply valve for making the pressure inside the fuel cell stack and the unreacted fuel gas circulation path positive with respect to the atmospheric pressure, and reduce the power consumption for opening and closing the fuel supply valve. And the power generation efficiency of the fuel cell system can be improved.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the present embodiment.
(Embodiment 1)
FIG. 1 shows a block diagram of a fuel cell system according to Embodiment 1 of the present invention.

  In FIG. 1, the fuel cell system 100 includes fuel cell stacks 1-1 to 1-N, a fuel gas supply path 2, and a control unit 3. N is an integer of 2 or more.

  Here, reference numerals assigned to a plurality of identical elements will be described. For example, in the case of the fuel cell stacks 1-1, 1-2, and 1-N, the subscripts 1, 2, and N are given to distinguish the same elements from each other, and N fuel cell stacks are provided. In some cases, the serial number of the fuel cell stack is indicated.

  Moreover, the code | symbol which describes several identical element continuously is demonstrated. For example, when the fuel cell stacks 1-1 to 1-3 are described, the symbols “˜” indicate that all of 1-1, 1-2, and 1-3 are indicated.

  The fuel cell stacks 1-1 to 1-N generate power using fuel gas and an oxidant gas supplied by an oxidant gas supply unit (not shown). As the fuel cell stacks 1-1 to 1-N, solid polymer fuel cells are used.

  The fuel gas supply path 2 is a path for supplying fuel gas to the fuel cell stacks 1-1 to 1-N.

  The control part 3 should just have a control function, and is provided with the arithmetic processing part (not shown) and the memory | storage part (not shown) which memorize | stores a control program. An example of the arithmetic processing unit is a CPU. An example of the storage unit is a memory.

  Fuel gas is supplied from the fuel gas supply path 2 to the fuel cell stacks 1-1 to 1-N, and the outlets of the fuel cell stacks 1-1 to 1-N are sealed. When fuel gas is consumed for power generation in the fuel cell stacks 1-1 to 1-N, fuel gas corresponding to the consumed amount is supplied from the fuel gas supply path 2 to the fuel cell stacks 1-1 to 1-N. Is done. Further, while the power generation of the fuel cell stacks 1-1 to 1-N is stopped, the fuel in the fuel cell stacks 1-1 to 1-N is reduced due to a temperature drop of the fuel cell stacks 1-1 to 1-N. Even when the gas contracts, the fuel gas is supplied from the fuel gas supply path 2 to the fuel cell stacks 1-1 to 1-N.

  About the fuel cell system 100 comprised as mentioned above, the operation | movement and an effect | action are demonstrated below.

  When the fuel cell system 100 generates power, a device that generates power is determined from the fuel cell stacks 1-1 to 1-N according to the required power generation amount. Of the fuel cell stacks 1-1 to 1-N, the fuel gas corresponding to the amount used for power generation is supplied from the fuel gas supply path 2 to generate power. In addition, fuel gas is always supplied from the fuel gas supply path 2 to the fuel cell stacks 1-1 to 1-N that do not generate power, and the fuel cell stacks 1-1 to 1-N generate power. Although not, the internal pressure can be maintained at a positive pressure relative to the atmospheric pressure.

  Here, in the fuel cell system 100, a case where only the fuel cell stack 1-1 generates power and the other fuel cell stacks 1-2 to 1-N do not generate power will be described. The fuel cell stack 1-1 generates power using the fuel gas supplied from the fuel gas supply path 2. The fuel cell stacks 1-2 to 1-N are not generating power, but the fuel gas contracts due to a temperature drop or the like of the fuel cell stacks 1-2 to 1-N, and the fuel cell stacks 1-2 to 1-N The internal pressure drops. At that time, since the fuel gas supply path 2 of the fuel cell stack 1-1 and the fuel cell stacks 1-2 to 1-N is always in communication, the fuel gas is also sent to the fuel cell stacks 1-2 to 1-N. Supplied. Thereby, the pressure inside the fuel cell stacks 1-2 to 1-N can be maintained at a positive pressure with respect to the atmospheric pressure.

  Next, when the fuel cell system 100 does not generate power, the fuel cell stacks 1-1 to 1-N do not generate power, but the fuel gas stacks 1-1 to 1-N are always supplied with fuel gas. Fuel gas is supplied from the path 2. For this reason, the pressure in all the fuel cell stacks 1-1 to 1-N is maintained at a positive pressure with respect to the atmospheric pressure.

  As described above, in the present embodiment, the fuel cell system 100 generates power by changing the number of operating fuel cell stacks 1-1 to 1-N according to the target power generation amount, and is stopped. The fuel cell is supplied to the 1-1 to 1-N, the discharge of the unreacted fuel gas from the fuel cell stack 1-1 to 1-N is closed, and the stopped fuel cell stack 1-1 to 1-N By making the inside a positive pressure with respect to the atmospheric pressure, the number of electromagnetic valves such as a fuel supply valve for keeping the inside of the fuel cell stacks 1-1 to 1-N at a positive pressure with respect to the atmospheric pressure can be reduced. It becomes possible, and the power consumption for opening and closing the solenoid valve can be reduced. For this reason, the power generation efficiency of the fuel cell system 100 can be improved.

  Further, when the atmosphere enters the anode of the stopped stack, the mixed gas of hydrogen and oxygen may enter the flammable range. However, according to the present embodiment, the internal pressures of the fuel cell stacks 1-1 to 1-N, the fuel gas supply path 2, and the unreacted fuel gas circulation paths 4-1 to 4-N are related to power generation and shutdown. In addition, since a positive pressure with respect to the atmospheric pressure can always be maintained, a mixed gas of hydrogen and oxygen does not enter the combustible range at the anode.

  In the present embodiment, hydrogen gas is used as the fuel gas. However, the present invention is not limited to this, and hydrocarbons such as city gas and alcohols such as methanol may be used.

  Moreover, the control part 3 may be comprised by the single controller which performs centralized control, and may be comprised by the some controller which cooperates mutually and performs distributed control.

The fuel cell stacks 1-1 to 1-N are not limited to solid polymer fuel cells, but may be solid oxide fuel cells or phosphoric acid fuel cells.
(Embodiment 2)
FIG. 2 shows a block diagram of the fuel cell system according to Embodiment 2 of the present invention.

  In FIG. 2, the fuel cell system 200 includes a fuel cell stack 1-1 to 1-N, a fuel gas supply path 2, a controller 3, an unreacted fuel gas circulation path 4-1 to 4-N, Reactive fuel gas circulation means 5-1 to 5-N.

  Constituent elements that are the same as those in the first embodiment are given the same reference numerals, and descriptions thereof are omitted here. Reference numerals are also the same as those in the first embodiment.

  The fuel gas circulation paths 4-1 to 4-N pass unreacted fuel gas discharged from each of the plurality of fuel cell stacks 1-1 to 1-N to each of the plurality of fuel cell stacks 1-1 to 1-N. The fuel gas supply path 2 is joined.

  The unreacted fuel gas circulation means 5-1 to 5-N are constituted by a flow meter and a pump for sending fuel gas. The pump pressurizes the unreacted fuel gas and supplies the unreacted fuel gas to the fuel gas supply path 2. Supply.

  Fuel gas is supplied from the fuel gas supply path 2 to the fuel cell stacks 1-1 to 1-N. The unreacted fuel gas that has not been used for the reaction for generating electricity in the fuel cell stacks 1-1 to 1-N is discharged from the downstream of the fuel cell stacks 1-1 to 1-N, and the unreacted fuel gas circulation path 4 It circulates to the fuel gas supply path 2 corresponding to each fuel cell stack 1-1 to 1-N through -1 to 4-N. The flow rate of the unreacted fuel gas flowing through the unreacted fuel gas circulation paths 4-1 to 4-N is controlled by the unreacted fuel gas circulation means 5-1 to 5-N. By supplying unreacted fuel gas to one of the fuel cell stacks 1-1 to 1-N that generates power, the flow rate of the fuel gas supplied to the fuel cell stack 1-1 to 1-N that generates power is reduced. The flow rate of fuel gas consumed by power generation can be increased. Thereby, the power generation of the fuel cell stacks 1-1 to 1-N can be stabilized, and the power generation reliability of the fuel cell system 200 can be improved. For this reason, the unreacted fuel gas circulation means 5-1 to 5-N only need to operate corresponding to the ones that generate power among the fuel cell stacks 1-1 to 1-N.

  When gas is consumed for power generation in the fuel cell stacks 1-1 to 1-N, fuel gas corresponding to the consumed amount is supplied from the fuel gas supply path 2 to the fuel cell stacks 1-1 to 1-N. The Further, while the power generation of the fuel cell stacks 1-1 to 1-N is stopped, the fuel in the fuel cell stacks 1-1 to 1-N is reduced due to a temperature drop of the fuel cell stacks 1-1 to 1-N. Even when the gas contracts, the fuel gas is supplied from the fuel gas supply path 2 to the fuel cell stacks 1-1 to 1-N.

  The operation and action of the fuel cell system 200 configured as described above will be described below.

  When the fuel cell system 200 generates power, a device that generates power is determined from the fuel cell stacks 1-1 to 1-N according to the required power generation amount. By operating the unreacted fuel gas circulation means 5-1 to 5-N corresponding to the one that generates power among the fuel cell stacks 1-1 to 1-N, the fuel cell stacks 1-1 to 1-N generate power. The sum of the fuel gas and the unreacted fuel gas corresponding to the amount used in the step is supplied.

  The unreacted fuel gas flow rate circulated by the unreacted fuel gas circulation means 5-1 to 5-N is determined in advance according to the target power generation amount of each of the fuel cell stacks 1-1 to 1-N that generates power. Control the flow rate.

  In addition, fuel gas is always supplied from the fuel gas supply path 2 to the fuel cell stacks 1-1 to 1-N that do not generate power, and the fuel cell stacks 1-1 to 1-N generate power. Although not, the internal pressure can be maintained at a positive pressure relative to the atmospheric pressure. At this time, the unreacted fuel gas circulation means 5-1 to 5-N corresponding to the fuel cell stacks 1-1 to 1-N that do not generate power are not operated.

  Here, in the fuel cell system 200, only the fuel cell stack 1-2 to 1-3 generates power, and the other fuel cell stack 1-1 and the fuel cell stacks 1-4 to 1-N do not generate power. State. By operating the unreacted fuel gas circulation means 5-2 to 5-3 corresponding to the fuel cell stacks 1-2 to 1-3, the fuel cell stacks 1-2 to 1-3 are required for power generation. Supply more fuel gas than quantity fuel gas. In this manner, the fuel cell stacks 1-2 to 1-3 are generated while supplying the fuel gas and the unreacted fuel gas to the fuel cell stacks 1-2 to 1-3. The unreacted fuel gas circulation means 5-1 and the unreacted fuel gas circulation means 5-4 to 5-N corresponding to the fuel cell stack 1-1 and the fuel cell stacks 1-4 to 1-N that do not generate power stop operating. Do not circulate unreacted fuel gas. Although the fuel cell stack 1-1 and the fuel cell stacks 1-4 to 1-N are not generating power, the fuel gas is generated due to a temperature drop of the fuel cell stack 1-1 and the fuel cell stacks 1-4 to 1-N. The pressure inside the fuel cell stack 1-1 and the fuel cell stacks 1-4 to 1-N is reduced. At that time, the fuel cell stack 1-2 to 1-3 that generates power, the fuel cell stack 1-1 that does not generate power, and the fuel gas supply path 2 of the fuel cell stacks 1-4 to 1-N always communicate with each other, Fuel gas is also supplied to the fuel cell stack 1-1 and the fuel cell stacks 1-4 to 1-N. Thereby, the pressure inside the fuel cell stack 1-1 and the fuel cell stacks 1-4 to 1-N can be maintained at a positive pressure with respect to the atmospheric pressure.

  Further, when the necessary power generation amount in the fuel cell system 200 increases, if the required power generation amount increases 1.5 times from the state where only the fuel cell stack 1-2 to 1-3 generates power, the fuel The battery stack 1-4 is started to generate power. In order to generate power from the fuel cell stack 1-4, first, the unreacted fuel gas circulation means 5-4 corresponding to the fuel cell stack 1-4 is operated to generate power for the fuel cell stack 1-4. Supply more fuel gas than the required amount of fuel gas. In this manner, the fuel cell stack 1-4 is generated while supplying the fuel gas and the unreacted fuel gas to the fuel cell stack 1-4.

  Next, when the fuel cell system 200 does not generate power, all the fuel cell stacks 1-1 to 1-N do not generate power, but fuel gas is always supplied to the fuel cell stacks 1-1 to 1-N. Fuel gas is supplied from the path 2. For this reason, the pressure in all the fuel cell stacks 1-1 to 1-N is maintained at a positive pressure with respect to the atmospheric pressure. At this time, all the unreacted fuel gas circulation means 5-1 to 5-N are stopped.

  As described above, in the present embodiment, the fuel cell system 200 generates power by changing the number of operating fuel cell stacks 1-1 to 1-N according to the target power generation amount, and is stopped. The fuel gas is supplied to 1-1 to 1-N, and the inside of the stopped fuel cell stacks 1-1 to 1-N and the unreacted fuel gas circulation paths 4-1 to 4-N are positive with respect to the atmospheric pressure. By adjusting the pressure, it becomes possible to reduce the number of solenoid valves such as a fuel supply valve for keeping the inside of the fuel cell stacks 1-1 to 1-N at a positive pressure with respect to the atmospheric pressure. Power consumption for opening and closing a simple solenoid valve can be reduced. For this reason, the power generation efficiency of the fuel cell system 200 can be improved.

  In the present embodiment, the unreacted fuel gas is circulated to the fuel cell stacks 1-1 to 1-N to be generated using the unreacted fuel gas circulation means 5-1 to 5-N. The fuel cell stacks 1-1 to 1-N can supply fuel gas at a flow rate higher than the fuel gas flow rate required to generate power among the fuel cell stacks 1-1 to 1-N. The power generation can be stabilized.

  Further, when the atmosphere enters the anode of the stopped stack, the mixed gas of hydrogen and oxygen may enter the flammable range. However, according to the present embodiment, the internal pressures of the fuel cell stacks 1-1 to 1-N, the fuel gas supply path 2, and the unreacted fuel gas circulation paths 4-1 to 4-N are related to power generation and shutdown. In addition, since a positive pressure with respect to the atmospheric pressure can always be maintained, a mixed gas of hydrogen and oxygen does not enter the combustible range at the anode.

  In addition, although hydrogen gas was used as fuel gas, not only this but hydrocarbons, such as city gas, alcohol, such as methanol, etc. may be sufficient.

  Moreover, the control part 3 may be comprised by the single controller which performs centralized control, and may be comprised by the some controller which cooperates mutually and performs distributed control.

  The fuel cell stacks 1-1 to 1-N are not limited to solid polymer fuel cells, but may be solid oxide fuel cells or phosphoric acid fuel cells.

  Further, the unreacted fuel gas flow rate circulated by the unreacted fuel gas circulation means 5-1 to 5-N detects the power generation amount of each of the fuel cell stacks 1-1 to 1-N that is generating power, You may control based on each electric power generation amount. This control not only stabilizes the power generation of the fuel cell stacks 1-1 to 1-N, but also sets the unreacted fuel gas circulation means 5-1 to 5-N to a necessary unreacted fuel gas flow rate. On the other hand, since it can operate without waste, the power consumption of the unreacted fuel gas circulation means 5-1 to 5-N can be reduced.

  As described above, the fuel cell system according to the present invention maintains the internal pressure of the fuel cell stack in a power generation stop state at a positive pressure with respect to the atmospheric pressure without using an electromagnetic valve such as a fuel supply valve. Therefore, it is useful for a fuel cell system that requires high power generation efficiency and reliability.

1-1 to 1-N Fuel cell stack 2 Fuel gas supply path 3 Control unit 4-1 to 4-N Unreacted fuel gas circulation path 5-1 to 5-N Unreacted fuel gas circulation means 100, 200 Fuel cell system

Claims (5)

A plurality of fuel cell stacks for generating electricity using a fuel gas containing hydrogen and an oxidant gas;
A fuel gas supply path for supplying fuel gas;
A control unit,
The control unit generates power by changing the number of operating fuel cell stacks according to a target power generation amount,
Supplying fuel gas to the stopped fuel cell stack, closing discharge of unreacted fuel gas from the fuel cell stack, and setting the inside of the stopped fuel cell stack to a positive pressure with respect to atmospheric pressure;
Fuel cell system. A plurality of fuel cell stacks for generating electricity using a fuel gas containing hydrogen and an oxidant gas;
A fuel gas supply path for supplying fuel gas to the plurality of fuel cell stacks;
A plurality of unreacted fuel gas circulation paths for joining unreacted fuel gas discharged from each of the plurality of fuel cell stacks to respective fuel gas supply paths of the plurality of fuel cell stacks;
A plurality of unreacted fuel gas circulation means provided in each of the plurality of unreacted fuel gas circulation paths;
A control unit,
The control unit generates power by changing the number of operating fuel cell stacks according to a target power generation amount,
Supplying fuel gas to the stopped fuel cell stack, and setting the inside of the stopped fuel cell stack and the inside of the unreacted fuel gas circulation path to a positive pressure with respect to atmospheric pressure;
Fuel cell system.   The control unit controls the flow rate of unreacted fuel gas supplied to the plurality of operating fuel cell stacks by the unreacted fuel gas circulation means based on the power generation amount of each of the plurality of operating fuel cell stacks. The fuel cell system according to claim 2. A plurality of fuel cell stacks for generating electricity using a fuel gas containing hydrogen and an oxidant gas;
A fuel cell system operating method comprising a fuel gas supply path for supplying fuel gas,
Changing the number of operating fuel cell stacks according to the target power generation amount to generate power; and
Supplying fuel gas to the stopped fuel cell stack, closing discharge of unreacted fuel gas from the fuel cell stack, and setting the inside of the stopped fuel cell stack to a positive pressure with respect to atmospheric pressure; A method for operating a fuel cell system. A plurality of fuel cell stacks for generating electricity using a fuel gas containing hydrogen and an oxidant gas;
A fuel gas supply path for supplying fuel gas to the plurality of fuel cell stacks;
A plurality of unreacted fuel gas circulation paths for joining unreacted fuel gas discharged from each of the plurality of fuel cell stacks to respective fuel gas supply paths of the plurality of fuel cell stacks;
A method of operating a fuel cell system comprising a plurality of unreacted fuel gas circulation means provided in each of the plurality of unreacted fuel gas circulation paths,
Changing the number of operating fuel cell stacks according to the target power generation amount to generate power; and
Supplying a fuel gas to the stopped fuel cell stack, and setting the inside of the stopped fuel cell stack and the unreacted fuel gas circulation path to a positive pressure with respect to the atmospheric pressure. how to drive.

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