JP2019125537A - Fuel cell system and operation method therefor - Google Patents

Abstract

To inhibit power generation efficiency from reducing in a fuel cell system constituted by a plurality of fuel cells.SOLUTION: A fuel cell system comprises: fuel gas discharge paths 4-1 to 4-3 for discharging fuel gas in fuel gas circulation paths 3-1 to 3-3; a shared fuel gas discharge path 5 having one end communicating with downstream ends of the fuel gas discharge paths 4-1 to 4-3 and the other end exposed to the atmosphere; opening/closing valves 7-1 to 7-3 that open/close the fuel gas discharge paths 4-1 to 4-3 and are normally closed; a discharge valve 6 that opens/closes the shared fuel gas discharge path 5 and is normally opened; and a controller 8. The controller 8 makes the discharge valve 6 be in a closed state before making opening/closing valves 7-1, 7-2 for fuel cells 1-1, 1-2 during power generation operation and an opening/closing valve 7-3 for a fuel cell 1-3 during power generation stop be into an opened state; after the elapse of a predetermined time, makes the opening/closing valve 7-3 for the fuel cell 1-3 during the power generation stop return into a closed state and make the discharge valve 6 be into an opened state; and, after that, makes the opening/closing valves 7-1, 7-2 for the fuel cells 1-1, 1-2 during the power generation operation be into a closed state.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fuel cell system including a plurality of fuel cells provided with a fuel gas circulation path and a method of operating the same.

  In recent years, development of a highly efficient and clean energy source is required, and a fuel cell is attracting attention as a candidate therefor. A fuel cell (for example, a polymer electrolyte fuel cell) includes a fuel gas containing hydrogen supplied to the anode of the fuel cell (hydrogen-rich gas), an air containing oxygen supplied to the cathode of the fuel cell, etc. It is a device that generates electric power by causing an electrochemical reaction (power generation reaction) with an oxidant gas.

  In a fuel cell system equipped with this fuel cell, when power generation is stopped, the air blower is stopped to stop the oxidant gas supply to the cathode, and the fuel gas supply is closed to stop the fuel gas supply to the anode. It is common to do.

  At this time, particularly in the case of a polymer electrolyte fuel cell, when the fuel gas supply to the anode of the fuel cell is stopped while being left, hydrogen of the anode diffuses to the cathode through the electrolyte membrane, The hydrogen of the anode will be greatly reduced. As a result, air can easily enter the anode.

  Then, when air intrudes into the anode and oxygen in the air comes in contact with the catalyst layer of the anode, the catalyst metal is oxidatively degraded to cause the performance deterioration of the fuel cell.

  Therefore, while the primary shutoff valve between the hydrogen tank and the fuel cell is closed during the fuel cell shutdown period, the secondary shutoff valve is opened to re-supply the fuel gas from the high pressure piping to the anode. A fuel cell system has been proposed in which oxygen is prevented from being adsorbed to the catalyst layer of the anode while maintaining the state of the presence of hydrogen (see Patent Document 1, for example).

JP 2008-4564 A

  However, in the conventional configuration proposed in Patent Document 1, since the fuel gas is resupplied from the high-pressure pipe to the anode during the power generation stop period, extra fuel gas (hydrogen) which can not be used for power generation is required. It had the problem of falling.

  The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a fuel cell system capable of improving power generation efficiency by effectively using a fuel gas.

In order to solve the above-mentioned conventional problems, the fuel cell system of the present invention is provided separately for each of a plurality of fuel cells, and supplies unused fuel gas discharged from the anode of the fuel cell to the anode as fuel gas. And a fuel gas discharge path for discharging the fuel gas in the fuel gas circulation path branched from the plurality of fuel gas circulation paths, and a downstream end of the plurality of fuel gas discharge paths at one end A common fuel gas discharge path communicating with the other end open to the atmosphere, a normally closed on / off valve individually provided for each of the plurality of fuel gas discharge paths to open and close the fuel gas discharge path, and The fuel cell system includes a normally open discharge valve for opening and closing the shared fuel gas discharge path, and a controller, wherein the controller is configured to perform at least one fuel operation during power generation operation while power generation is stopped for at least one fuel cell. When the on-off valve corresponding to the battery is opened, the on-off valve corresponding to at least one fuel cell in power generation operation after closing the discharge valve and at least one fuel cell in power generation suspension are supported The open / close valve is opened, and the open / close valve corresponding to the at least one fuel cell under power generation stop is opened, and the open / close valve corresponding to the at least one fuel cell under power generation stop To the closed state, the exhaust valve to the open state, and the on-off valve corresponding to the at least one fuel cell in the cessation of power generation to the closed state, and then to the at least one fuel cell in power generation operation Control is performed to close the on-off valve.

  By this, when the fuel cell in the power generation operation and the fuel cell in the power generation suspension coexist, conventionally, the fuel off gas having a low concentration of hydrogen discharged from the fuel cell in the power generation operation to the atmosphere is generated It is possible to supply to the anode of the fuel cell in suspension, increase the gas pressure in the anode of the fuel cell in suspension of power generation, and prevent air from invading the anode of the fuel cell in suspension of power generation. Fuel gas can be used effectively and power generation efficiency can be improved.

  In the fuel cell system of the present invention, when the fuel cell in the power generation operation and the fuel cell in the power generation stop coexistence, conventionally, the concentration of hydrogen discharged from the fuel cell in the power generation operation into the atmosphere is low. The fuel off gas is supplied to the anode of the fuel cell during power generation stoppage, and the gas pressure in the fuel cell anode during power generation stoppage is increased to prevent the oxidation deterioration of the catalyst layer of the anode while preventing the whole fuel cell system. Can be suppressed.

  As a result, when the same power generation output is obtained, the amount of fuel gas used in the fuel cell system can be reduced. Therefore, the fuel gas can be effectively used, and the power generation efficiency can be improved.

Block diagram showing a schematic configuration of a fuel cell system according to Embodiment 1 of the present invention Flowchart showing operation method of fuel cell system according to Embodiment 1 of the present invention Block diagram showing a schematic configuration of a fuel cell system according to Embodiment 2 of the present invention Flow chart showing operation method of fuel cell system in Embodiment 2 of the present invention Block diagram showing a schematic configuration of a fuel cell system according to Embodiment 3 of the present invention Flowchart showing operation method of fuel cell system according to Embodiment 3 of the present invention

According to a first aspect of the present invention, there are provided a plurality of fuel cells, a fuel gas supply path individually provided for each of the plurality of fuel cells, for supplying fuel gas to the anode of the fuel cells, and a plurality of fuel cells individually. Fuel gas circulation path is provided to return unused fuel gas discharged from the anode of the fuel cell as fuel gas back to the fuel gas supply path, and from a plurality of fuel gas circulation paths to discharge fuel gas in the fuel gas circulation path For each fuel gas discharge path, one end of the common fuel gas discharge path communicating with the downstream end of the plurality of fuel gas discharge paths and the other end opened to the atmosphere, and the plurality of fuel gas discharge paths A fuel cell system comprising: a normally closed on-off valve for opening and closing a gas discharge path; a normally open exhaust valve for opening and closing a common fuel gas exhaust path provided in the common fuel gas discharge path; and a controller A.

  When the controller opens the on-off valve corresponding to the at least one fuel cell in power generation operation while the power generation of at least one fuel cell is stopped, the controller closes the discharge valve and then performs at least one operation. The on-off valve corresponding to the fuel cell in the power generation operation of the stand and the on-off valve corresponding to the fuel cell in the power generation stoppage are opened, and the on-off valve corresponding to the fuel cell in the power generation stoppage After a predetermined time elapses from opening the valve, return the on-off valve corresponding to at least one fuel cell whose power generation is stopped to the closed state and open the discharge valve, and at least one fuel cell whose power is stopped The fuel cell system performs control to close the on-off valve corresponding to at least one fuel cell in power generation operation after returning the on-off valve corresponding to the closed state.

  Generally, the fuel cell can not react 100% of the fuel gas supplied to the anode, so the anode is supplied with more fuel gas than necessary. Then, the unused fuel gas (fuel off gas) discharged from the anode is returned to the fuel gas supply path by the fuel gas circulation path, and is reused as the fuel gas.

  In particular, in the case of a polymer electrolyte fuel cell, the air of the cathode is likely to permeate the electrolyte membrane and move to the anode, and the concentration of impurities contained in the fuel gas circulating in the fuel gas circulation path increases with the passage of operation time. Since the power generation performance is lowered due to the increase, the fuel gas circulating cyclically through the fuel gas circulation path along with the impurities is mixed with the fuel gas so that the concentration of the impurities contained in the fuel gas circulating through the fuel gas circulation path is not excessively high. Exhaust from circulation.

  When the controller in the fuel cell system according to the first aspect of the invention opens the on-off valve corresponding to at least one fuel cell in power generation operation while the power generation of at least one fuel cell is stopped, the discharge valve Since the on / off valve corresponding to at least one fuel cell in power generation operation after being closed and the on / off valve corresponding to at least one fuel cell in power generation suspension state are opened, the fuel cell in power generation operation The fuel gas circulating in the fuel gas circulation path of the fuel gas discharge path of the fuel cell during power generation operation and the fuel gas discharge path of the fuel cell during power generation stoppage by the opening operation of the on-off valve and the pressure difference. The gas flows into the anode of the fuel cell under power generation stop via the fuel gas circulation path of the fuel cell under power generation stop, and the gas pressure in the anode of the fuel cell during power generation stop rises to about atmospheric pressure, and power generation is stopped Of the fuel cell inside Air is less likely to invade over de.

  When the fuel cells in power generation operation and the anodes of the fuel cells in power generation suspension communicate with each other for a predetermined time, the pressure difference between the fuel cells in power generation operation and the anodes of the fuel cells in power generation suspension becomes too small. Since the fuel gas hardly flows into the fuel cell anode during power generation stop, the controller closes the fuel cell on / off valve during power generation stop.

  The controller returns the open / close valve corresponding to the at least one fuel cell in the cessation of power generation to the closed state after a predetermined time has elapsed since the gate valve corresponding to the fuel cell in the cessation of power generation is opened. At the same time, after the release valve is opened and the on-off valve corresponding to the at least one fuel cell in the power generation stop state is closed, the on-off valve corresponding to the at least one fuel cell in power generation operation is closed Therefore, after sufficiently increasing the gas pressure in the anode of the fuel cell during power generation stop, the remaining destination of the fuel off gas (fuel gas) with low residual hydrogen concentration (high impurity concentration) is during power generation stop. By switching the fuel cell from the fuel cell to the common fuel gas discharge path (in the atmosphere) and discharging the fuel off gas with a low residual hydrogen concentration (high impurity concentration) from the common fuel gas discharge path to the atmosphere, Power generation The hydrogen concentration in the fuel gas circulating in the fuel gas circulation path of the fuel cell Sakuchu can be returned to a high (low impurity concentration) state.

Therefore, when the fuel cell in the power generation operation and the fuel cell in the power generation stop coexist, conventionally, the hydrogen concentration discharged from the fuel cell in the power generation operation to the atmosphere is low (the impurity concentration is high) The fuel off gas (fuel gas) is supplied to the anode of the fuel cell during power generation suspension, and the pressure of the fuel cell anode during power generation suspension is reduced due to the decrease of hydrogen with the lapse of time from the power generation suspension. It becomes possible to suppress the entry of air into the anode of the fuel cell during power generation stop, and prevent the oxidation deterioration of the catalyst layer of the anode of the fuel cell during power generation stop while the power generation of the entire fuel cell system It is possible to suppress the decrease in efficiency.

  In addition, since the on-off valve is kept in the closed state except when the fuel gas is introduced into the fuel cell under power generation stop, when the fuel gas consumption amount of the plurality of fuel cells under power generation stop is different, It prevents the fuel gas from moving from the fuel cell with low fuel gas consumption toward the fuel cell with high fuel gas consumption, and prevents the oxidation degradation of the anode side catalyst layer of the fuel cell with low fuel gas consumption. be able to.

  In the fuel cell system according to the second aspect of the present invention, in particular, the controller in the fuel cell system according to the first aspect may be configured to stop the generation of at least two fuel cells during the generation operation of at least one fuel cell. When the consumption of fuel gas during power generation suspension differs among the fuel cells of the two fuel cells, the fuel gas is supplied to the anode of the fuel cell with the largest consumption of fuel gas among the plurality of fuel cells during power generation suspension. The on-off valves of a plurality of fuel cells being stopped during power generation are controlled so as to flow more in.

  This makes it possible to supply more fuel gas to the fuel cell that consumes a large amount of fuel gas during stoppage among the plurality of fuel cells that are under power generation stoppage, so It is possible to prevent the progress of the oxidative deterioration of the catalyst layer of the anode of the fuel cell that consumes a large amount, and make the progress of the deterioration of the entire fuel cell during power generation stoppage uniform.

  In the fuel cell system according to the third aspect of the present invention, in particular, the controller in the fuel cell system according to the first aspect may be configured to stop the generation of at least two fuel cells during power generation operation of at least one fuel cell. When the open circuit voltage immediately after the end of the power generation operation is different among the fuel cells of the stand, the fuel of the fuel cell whose open circuit voltage is low immediately after the end of the power generation operation is the fuel. The on-off valves of the plurality of fuel cells during power generation stop are controlled so that more gas flows in.

  As a result, it is possible to supply more fuel gas to the fuel cell having a low open circuit voltage immediately after the end of the power generation operation among the plurality of fuel cells whose power generation is stopped. It is possible to prevent the progress of the oxidative deterioration of the catalyst layer of the anode of the fuel cell having a low circuit voltage, and to equalize the progress of the deterioration of the entire fuel cell while the power generation is stopped.

  In the fuel cell system according to the first aspect of the present invention, in particular, the controller in the fuel cell system according to the first aspect may be configured to stop the generation of at least two fuel cells during the generation operation of at least one fuel cell. In the case where the elapsed time from the power generation stop between the two fuel cells is different, among the plurality of fuel cells in the power generation stop, the fuel cell has a long elapsed time since the power generation stop. The on-off valves of the plurality of fuel cells during power generation stop are controlled so that more gas flows in.

  As a result, it is possible to supply more fuel gas to the fuel cell having a long elapsed time after the power generation is stopped among the plurality of fuel cells whose power generation is stopped. It is possible to prevent the progress of the oxidation deterioration of the catalyst layer of the anode of the fuel cell which has a long elapsed time, and to equalize the progress of the deterioration of the whole fuel cell during the power generation stop.

According to the fifth aspect of the present invention, in particular, the controller in the fuel cell system according to any one of the second to fourth aspects of the present invention is in the process of stopping power generation with respect to the number of times the on / off valve of the fuel cell is in an open state. The number of times the on-off valve of the fuel cell is open is controlled.

  This makes it possible to change the amount of fuel gas supplied to each of the plurality of fuel cells whose power generation is stopped.

  In a sixth aspect of the present invention, there are provided a plurality of fuel cells, a fuel gas supply path individually provided for each of the plurality of fuel cells, for supplying fuel gas to the anode of the fuel cells, and a plurality of fuel cells individually. Fuel gas circulation path is provided to return unused fuel gas discharged from the anode of the fuel cell as fuel gas back to the fuel gas supply path, and from a plurality of fuel gas circulation paths to discharge fuel gas in the fuel gas circulation path For each fuel gas discharge path, one end of the common fuel gas discharge path communicating with the downstream end of the plurality of fuel gas discharge paths and the other end opened to the atmosphere, and the plurality of fuel gas discharge paths Method of operating a fuel cell system comprising: a normally closed on / off valve for opening and closing a gas discharge path; and a normally open exhaust valve for opening and closing a shared fuel gas discharge path provided in the shared fuel gas discharge path A.

  When the on-off valve corresponding to at least one fuel cell in power generation operation is opened while the power generation of at least one fuel cell is stopped, the discharge valve is closed and then at least one power generation operation is performed. Open the open / close valve corresponding to the fuel cell in the middle and the open / close valve corresponding to the fuel cell in the power generation stop state, and open the open / close valve corresponding to the fuel cell in the power generation stop state. After an elapse of a predetermined time, the on-off valve corresponding to at least one fuel cell whose power generation is stopped is returned to the closed state, and the discharge valve is opened, and the power valve corresponding to at least one fuel cell whose power is stopped It is an operation method of a fuel cell system which closes an on-off valve corresponding to a fuel cell in operation of at least one set of power generation after returning the valve to the closed state.

  Generally, the fuel cell can not react 100% of the fuel gas supplied to the anode, so the anode is supplied with more fuel gas than necessary. Unused fuel gas (fuel off gas) discharged from the anode is returned to the fuel gas supply path by the fuel gas circulation path and reused as fuel gas.

  In particular, in the case of a polymer electrolyte fuel cell, the air of the cathode is likely to permeate the electrolyte membrane and move to the anode, and the concentration of impurities contained in the fuel gas circulating in the fuel gas circulation path increases with the passage of operation time. Since the power generation performance is lowered due to the increase, the fuel gas circulating cyclically through the fuel gas circulation path along with the impurities is mixed with the fuel gas so that the concentration of the impurities contained in the fuel gas circulating through the fuel gas circulation path is not excessively high. Exhaust from circulation.

  In the method of operating a fuel cell system according to the sixth aspect of the present invention, the exhaust valve is opened when the on-off valve corresponding to the fuel cell in operation of at least one power generation is opened while the power generation of at least one fuel cell is stopped. Since the on / off valve corresponding to at least one fuel cell in power generation operation after being closed and the on / off valve corresponding to at least one fuel cell in power generation suspension state are opened, the fuel cell in power generation operation The fuel gas circulating in the fuel gas circulation path of the fuel gas discharge path of the fuel cell during power generation operation and the fuel gas discharge path of the fuel cell during power generation stoppage by the opening operation of the on-off valve and the pressure difference. The gas flows into the anode of the fuel cell under power generation stop via the fuel gas circulation path of the fuel cell under power generation stop, and the gas pressure in the anode of the fuel cell during power generation stop rises to about atmospheric pressure, and power generation is stopped Anoh of fuel cell inside Air is less likely to invade.

  When the fuel cells in power generation operation and the anodes of the fuel cells in power generation suspension communicate with each other for a predetermined time, the pressure difference between the fuel cells in power generation operation and the anodes of the fuel cells in power generation suspension becomes too small. Since the inflow of fuel gas to the anode of the fuel cell during power generation stop is almost eliminated, the on-off valve of the fuel cell during power generation stop is closed.

  In addition, after a predetermined time has elapsed since the on-off valve corresponding to at least one fuel cell in power generation suspension is opened, the on-off valve corresponding to at least one fuel cell in suspension of power generation is closed. After opening the discharge valve and returning the on-off valve corresponding to at least one fuel cell in power generation stop to the closed state, close the on-off valve corresponding to at least one fuel cell in power generation operation Therefore, after sufficiently increasing the gas pressure in the anode of the fuel cell during power generation stop, the remaining destination of the fuel off gas (fuel gas) with low residual hydrogen concentration (high impurity concentration) is the fuel during power generation stop. By switching from the battery to the common fuel gas discharge path (in the atmosphere) and releasing the fuel off gas with a low residual hydrogen concentration (high impurity concentration) from the common fuel gas discharge path to the atmosphere, the on-off valve is opened to generate electricity. The hydrogen concentration in the fuel gas circulating in the fuel gas circulation path of the fuel cell can be returned to a high (low impurity concentration) state.

  Therefore, when the fuel cell in the power generation operation and the fuel cell in the power generation stop coexist, conventionally, the hydrogen concentration discharged from the fuel cell in the power generation operation to the atmosphere is low (the impurity concentration is high) The fuel off gas (fuel gas) is supplied to the anode of the fuel cell during power generation suspension, and the pressure of the fuel cell anode during power generation suspension is reduced due to the decrease of hydrogen with the lapse of time from the power generation suspension. It becomes possible to suppress the entry of air into the anode of the fuel cell during power generation stop, and prevent the oxidation deterioration of the catalyst layer of the anode of the fuel cell during power generation stop while the power generation of the entire fuel cell system It is possible to suppress the decrease in efficiency.

  In addition, since the on-off valve is kept in the closed state except when the fuel gas is introduced into the fuel cell under power generation stop, when the fuel gas consumption amount of the plurality of fuel cells under power generation stop is different, It prevents the fuel gas from moving from the fuel cell with low fuel gas consumption toward the fuel cell with high fuel gas consumption, and prevents the oxidation degradation of the anode side catalyst layer of the fuel cell with low fuel gas consumption. be able to.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited by the present embodiment. In all of the following drawings, the same or corresponding parts will be denoted by the same reference numerals, and overlapping descriptions will be omitted.

Embodiment 1
FIG. 1 is a block diagram showing a schematic configuration of a fuel cell system according to Embodiment 1 of the present invention. FIG. 2 is a flowchart showing a method of operating a fuel cell system according to Embodiment 1 of the present invention.

  As shown in FIG. 1, the fuel cell system 100 of Embodiment 1 has three fuel cells 1-1, 1-2, and 1-3 connected in parallel.

  The three fuel cells 1-1, 1-2, and 1-3 each have an electrolyte membrane formed by depositing a solid polymer electrolyte (ionomer) having hydrogen ion conductivity, and a cathode provided so as to sandwich the electrolyte membrane. (Catalyst layer) and anode (catalyst layer), fuel gas flow path for supplying hydrogen as fuel gas, and a pair of flat plates made of carbon in which an oxidant gas flow path for supplying air as an oxidant gas is formed The fuel cell stack is configured of a plurality of fuel cell stacks formed by stacking a plurality of fuel cells stacked and fastened.

  In this embodiment mode, the impurity gas contained in hydrogen is nitrogen. The anode is formed on one surface of the electrolyte membrane so as to face the cathode, and is composed of carbon on which platinum particles are supported and a solid polymer electrolyte having hydrogen ion conductivity.

Fuel gas supply paths 2-1, 2-2, 2-3 for individually supplying hydrogen to the fuel cells 1-1, 1-2, 1-3 are provided. The fuel gas supply paths 2-1, 2-2, and 2-3 are configured by gas pipes. The fuel gas supply passages 2-1, 2-2, 2-3 are fuel gas passages of the anode side separator disposed in each of the fuel cells constituting the fuel cells 1-1, 1-2, 1-3. And connected.

  In this manner, hydrogen supplied from the fuel gas supply channels 2-1, 2-2, and 2-3 is configured to reach each anode of the fuel cells 1-1, 1-2, and 1-3. ing.

  In addition, fuel gas is supplied to the fuel cells 1-1, 1-2 and 1-3 separately from unused fuel gas (fuel off gas) discharged from the fuel cells 1-1, 1-2 and 1-3. Fuel gas circulation paths 3-1, 3-2, and 3-3 are provided to return to the paths 2-1, 2-2, and 2-3. The fuel gas circulation paths 3-1, 3-2 and 3-3 are constituted by gas pipes.

  Further, the three fuel cells 1-1, 1-2, and 1-3 are individually branched from the fuel gas circulation paths 3-1, 3-2, and 3-3, and the fuel gas circulation paths 3-1, 3 and 3 are branched. Fuel gas discharge paths 4-1, 4-2, and 4-3 are provided to discharge the fuel gas circulating through 2-3.

  In the fuel gas discharge paths 4-1, 4-2, 3-4, the concentration of nitrogen contained in the fuel gas circulating in the fuel gas circulation paths 3-1, 3-2, 3-3 does not become equal to or higher than a predetermined concentration. The fuel gas circulation paths 3-1, 3-2, and 3-3 are paths for discharging the fuel gas out of the system of the fuel gas circulation paths 3-1, 3-2, and 3-3.

  In the fuel cell system 100, a common fuel gas discharge path 5 is provided, one end of which is in communication with the downstream end of the plurality of fuel gas discharge paths 4-1, 4-2 and 4-3 and the other end is open to the atmosphere. . Further, the common fuel gas discharge passage 5 is provided with a normally open (usually in an open state) discharge valve 6 for opening and closing the common fuel gas discharge passage 5. The discharge valve 6 is constituted by a solenoid valve which can switch the degree of opening to full open or full close by energization and non-energization.

  In addition, normally closed (usually in a closed state) for opening and closing the fuel gas discharge paths 4-1, 4-2, and 3-4 individually in the fuel gas discharge paths 4-1, 4-2, and 3-4, respectively. On-off valves 7-1, 7-2, 7-3 are provided.

  The on-off valves 7-1, 7-2, 7-3 are constituted by solenoid valves capable of switching the degree of opening to full open or full close by energization and deenergization, and the fuel cell 1-1, 1 during power generation operation In -2, 1-3, when the concentration of nitrogen in the fuel gas becomes equal to or higher than the predetermined concentration, the fuel gas discharge passage is opened from the fuel gas discharge passage 4-1, 4-2 and 4-3 and the common fuel gas discharge passage is opened. 5 has a function of discharging the fuel gas and adjusting the concentration of nitrogen contained in the fuel gas circulating through the fuel gas circulation paths 3-1, 3-2 and 3-3 so as not to exceed a predetermined concentration.

  Here, the unused fuel gas (fuel off gas) discharged from the anode of each of the fuel cells 1-1, 1-2, and 1-3 has a fuel gas circulation path 3-1, 3-2, 3-3. The nitrogen in the air permeates from the cathode side to the anode side through the electrolyte membranes of the fuel cells 1-1, 1-2, and 1-3 and is concentrated. In this case, the power generation of the fuel cells 1-1, 1-2, and 1-3 is significantly reduced.

  Therefore, periodically, nitrogen is discharged into the atmosphere together with unused hydrogen. Moreover, in order to perform such operation | movement, the controller 8 for controlling the discharge valve 6 and on-off valve 7-1, 7-2, 7-3 is provided.

  The operation and action of the fuel cell system 100 according to the present embodiment configured as described above will be described below with reference to FIGS. 1 and 2.

  The fuel cell system 100 of the present embodiment shown in FIG. 1 executes the operation of the flow chart of FIG. 2 under the control of the controller 8. In the first embodiment, it is assumed that the fuel cell 1-1 and the fuel cell 1-2 are generating power and the fuel cell 1-3 is not generating power.

  First, the discharge valve 6 of the common fuel gas discharge passage 5 is closed (S101). Next, open the on-off valves 7-1 and 7-2 of the fuel cells 1-1 and 1-2 in the power generation operation and the on-off valve 7-3 of the fuel cell 1-3 in the power generation suspension state. Hold for a second (S102). Next, the on-off valve 7-3 of the fuel cell 1-3 in which the power generation is stopped is closed, and the discharge valve 6 is opened for 30 seconds (S103).

  Next, the on-off valves 7-1 and 7-2 of the fuel cells 1-1 and 1-2 during power generation operation are closed, held for 10 minutes (S104), and the process returns to S101. In each step, immediately after the completion of the previous step, transition is made promptly without providing a waiting time.

  As described above, as shown in FIG. 1, the fuel cell system 100 according to the present embodiment includes a plurality of (three) fuel cells 1-1, 1-2, and 1-3 and a plurality of (three) fuel cells. A fuel gas supply path 2-1 provided separately for each of the fuel cells 1-1, 1-2, and 1-3 for supplying fuel gas to the anodes of the fuel cells 1-1, 1-2, and 1-3. , 2-2, 2-3, and a plurality of (three) fuel cells 1-1, 1-2, 1-3 individually provided for the fuel cells 1-1, 1-2, 1-3. A plurality of fuel gas circulation paths 3-1, 3-2, 3-3, which return unused fuel gas discharged from the anode to the fuel gas supply path 2-1, 2-2, 2-3 as fuel gas, The fuel gas circulation paths 3-1, 3-2, and 3-3 are discharged from the fuel gas circulation paths 3-1, 3-2, and 3-3, respectively. Of the fuel gas discharge path 4-1, 4-2 and 4-3, and one end thereof is in communication with the downstream end of the plurality (three) of fuel gas discharge paths 4-1, 4 and 2-4 and the other end is The shared fuel gas discharge passage 5 open to the atmosphere and the plurality (three) of the fuel gas discharge passages 4-1, 4-2 are individually provided in the fuel gas discharge passage 4-1, 4-2 respectively. , 4-3, and the normally closed (normally closed) on / off valves 7-1, 7-2, 7-3, and the shared fuel gas discharge path 5 which normally opens and closes the shared fuel gas discharge path 5 It is configured to include an open (usually in an open state) discharge valve 6 and a controller 8.

  Then, the controller 8 of the fuel cell system 100 according to the present embodiment opens and closes corresponding to the fuel cells 1-1 and 1-2 during two power generation operations while the power generation of one fuel cell 1-3 is stopped. When the valves 7-1 and 7-2 are opened, the exhaust valve 6 is closed (S101 in FIG. 2) to correspond to the two fuel cells 1-1 and 1-2 in power generation operation. Open the on-off valves 7-1 and 7-2 and the on-off valve 7-3 corresponding to the one fuel cell 1-3 in the power generation stop state (S102 in FIG. 2), and the fuel in the one power generation stop state After a predetermined time (90 seconds) has elapsed since the on-off valve 7-3 corresponding to the battery 1-3 is opened, the on-off valve 7-3 corresponding to one fuel cell 1-3 whose power generation is stopped is closed , And the discharge valve 6 is opened (S103 in FIG. 2), and the on-off valve 7-3 corresponding to the fuel cell 1-3 in power generation suspension is closed. 30 seconds after returning to (the step after S103 in FIG. 2), the on-off valves 7-1 and 7-2 corresponding to the fuel cells 1-1 and 1-2 in power generation operation are closed ( It is comprised so that control of S104 of FIG. 2 may be performed.

  Since the fuel cells 1-1, 1-2, and 1-3 can not react 100% of the fuel gas supplied to the anode, the fuel gas supply paths 2-1, 2-2, and 2-3 are connected to the anode. Supplies more fuel gas than is necessary. Then, unused fuel gas (fuel off gas) discharged from the anode is supplied to the fuel gas supply channels 2-1, 2-2, 2-3 by the fuel gas circulation channels 3-1, 3-2, 3-3. It is returned and reused as fuel gas.

  Since the fuel cells 1-1, 1-2, and 1-3 are solid polymer fuel cells, the air of the cathode easily permeates through the solid polymer electrolyte membrane and moves to the anode, and with the passage of the operation time, Since the concentration of the impurities contained in the fuel gas circulating through the fuel gas circulation route 3-1, 3-2, and 3-3 increases and the power generation performance decreases, the fuel gas circulation route 3-1, 3-2, and 3-3. The on-off valves 7-1, 7-2, 7-3 are periodically opened to prevent the concentration of the impurities contained in the fuel gas circulating through the fuel cell 3. Exhaust the fuel gas circulating through 3-2 and 3-3 together with the impurities from the fuel gas circulation passage 3-1, 2-3, 3-3 via the fuel gas discharge passage 4-1, 4-2, 3-4 Do.

  The controller 8 of the fuel cell system 100 according to the present embodiment has the on-off valve 7 corresponding to the fuel cells 1-1 and 1-2 during two power generation operations while the power generation of one fuel cell 1-3 is stopped. In the case where the fuel cell -1 and 7-2 are opened, the discharge valve 6 is closed and the on / off valve corresponding to the fuel cells 1-1 and 1-2 during two power generation operations from the state (S101 in FIG. 2) 7-1 and 7-2 and the on-off valve 7-3 corresponding to the one fuel cell 1-3 in suspension of power generation are opened (S102 in FIG. 2). The fuel gas circulating in the fuel gas circulation paths 3-1 and 3-2 of 1, 1-2 is subjected to the pressure difference by the opening operation of the on-off valves 7-1 and 7-2 and the fuel cell 1 in the power generation operation. -1, 1-2 fuel gas discharge path 4-1, 4-2, fuel gas discharge path 4-3 of the fuel cell 1-3 during power generation stop, and fuel discharge during power generation stop The gas pressure in the anode of the fuel cell 1-3 flowing into the anode of the fuel cell 1-3 which is in the cessation of power generation is about atmospheric pressure while flowing into the anode of the fuel cell 1-3 in the cessation of power generation As a result, the air is less likely to intrude into the anode of the fuel cell 1-3 during power generation stoppage.

  When the state in which the fuel cell 1-1.1-2 in the power generation operation and the anode of the fuel cell 1-3 in the power generation stop communicate with each other reaches a predetermined time (90 seconds), the fuel cell 1-1 in the power generation operation , 1-2 and the pressure difference between the anodes of the fuel cell 1-3 during power generation stop is too small, and the flow of the fuel gas to the anode of the fuel cell 1-3 during power generation stop is almost eliminated. The on-off valve 7-3 of the fuel cell 1-3 during power generation stoppage is closed by the fuel cell 8.

  The controller 8 opens the on-off valve 7-3 corresponding to the fuel cell 1-3 in the power generation stop state, and after a predetermined time (90 seconds) elapses, the fuel cells 1-1, 1-2 in the power generation stop state And the exhaust valve 6 is opened (S103 in FIG. 2), and the on-off valve 7-3 corresponding to the fuel cell 1-3 during power generation stoppage 30 seconds after returning to the closed state, the on-off valves 7-1 and 7-2 corresponding to the fuel cells 1-1 and 1-2 in the power generation operation are closed (S104 in FIG. 2), so power generation is stopped. After sufficiently increasing the gas pressure in the anode of the fuel cell 1-3, the remaining hydrogen concentration (high impurity concentration) of the fuel off gas (fuel gas) is the destination of the fuel Switch from 1 to 3 to shared fuel gas discharge path 5 (in air), and the remaining hydrogen concentration is low (impurity concentration is high By releasing the fuel off gas from the common fuel gas discharge path 5 to the atmosphere, the on-off valves 7-1 and 7-2 are opened to generate the fuel gas circulation path 3-1 of the fuel cells 1-1 and 1-2 during power generation operation. , 3-2 can be returned to the state of high hydrogen concentration (low impurity concentration) of the fuel gas.

  Therefore, when the fuel cells 1-1 and 1-2 in the power generation operation coexist with the fuel cells 1-3 in the power generation stop state, conventionally, from the fuel cells 1-1 and 1-2 in the power generation operation Fuel off gas (fuel gas) with a low concentration of hydrogen (high impurity concentration) discharged to the atmosphere is supplied to the anode of the fuel cell 1-3 during power generation suspension, and hydrogen accompanying the time lapse from the power generation suspension By reducing the pressure, it is possible to increase the pressure of the anode of the fuel cell 1-3 during power generation stoppage, and suppress air from invading the anode of the fuel cell 1-3 during power generation stoppage. It is possible to suppress the decrease in the power generation efficiency of the entire fuel cell system 100 while preventing the oxidation deterioration of the catalyst layer of the anode of the fuel cell 1-3 during the power generation stop.

  Further, in the present embodiment, the on-off valve 7-3 is held in the closed state except when the fuel gas is caused to flow into the fuel cell 1-3 during power generation stoppage.

  If the fuel cell 1-2 and the fuel cell 1-3 are not generating power and the fuel cell 1-2 consumes more fuel gas than the fuel cell 1-3, the fuel gas consumed is small Oxidative deterioration of the anode side catalyst layer of the fuel cell 1-3 which prevents the fuel gas from moving from the fuel cell 1-3 to the fuel cell 1-2 having a large consumption of fuel gas and has a small consumption of the fuel gas You can prevent.

  In the present embodiment, the three fuel cells 1-1, 1-2, and 1-3 are disposed in the fuel cell system 100. However, three or more fuel cells may be used instead of three. That is, when two or more fuel cells are disposed in the fuel cell system 100, and at least one of the fuel cells is not generating power, and at least one or more fuel cells are generating power. The present invention is effective.

  Note that the time interval for discharging the fuel off gas from the fuel cell 1-1, 1-2 during power generation operation, the supply time of the fuel off gas to the fuel cell 1-3 during power generation stop, and the setting time for discharge to the atmosphere Are the materials and operating conditions (current value, generated voltage, required power generation output, amount of supplied gas) constituting the fuel cell 1-1, 1-2, 1-3, the volume of the hydrogen supply connection member, the volume of the gas pipe, It is possible to set appropriately according to fuel cell structure design, such as the volume of the hydrogen channel of a separator.

  If the fuel cells 1-2 and 1-2 are not generating electricity while the fuel cell 1-1 is generating electricity, the amount of fuel gas consumed during the generation of fuel cell 1-2 is the fuel cell 1. If the fuel gas consumption during the power generation suspension is larger than the fuel cell consumption during the power generation suspension, the anode of the fuel cell 1-2 with the largest fuel gas consumption is selected. Control is performed to control the on-off valves 7-2 and 7-3 of the fuel cells 1-2 and 1-3 during power generation stoppage so that the fuel off gas of the fuel cell 1-1 during the power generation operation flows in more The unit 8 may be configured.

  In that case, among the plurality (two) of fuel cells 1-2 and 1-3 whose power generation is stopped, the fuel cell 1-2 which consumes a large amount of fuel gas during stoppage has more fuel gas Since it becomes possible to supply, the progress of the oxidation deterioration of the catalyst layer of the anode of the fuel cell 1-2 where the consumption of the fuel gas during the stop is large is prevented, and the progress of the deterioration of the entire fuel cell during the power generation stop is It can be made uniform.

Second Embodiment
FIG. 3 is a block diagram showing a schematic configuration of a fuel cell system according to Embodiment 2 of the present invention. FIG. 4 is a flow chart showing a method of operating a fuel cell system according to Embodiment 2 of the present invention.

  The fuel cell system 200 of Embodiment 2 shown in FIG. 3 is obtained by replacing the controller 8 of the fuel cell system 100 of Embodiment 1 shown in FIG. In the fuel cell system 200 according to the second embodiment, the same components as those of the fuel cell system 100 according to the first embodiment may be assigned the same reference numerals and redundant description may be omitted.

In addition to the control similar to the controller 8 of the fuel cell system 100 of Embodiment 1, the controller 9 of the fuel cell system 200 of Embodiment 2 includes, for example, the power generation operation of at least one fuel cell 1-1. When at least two fuel cells 1-2 and 1-3 are in the process of stopping power generation and the open circuit voltage of the fuel cell 1-2 is lower than the open circuit voltage of the fuel cell 1-3, the power generation is stopped Among the plurality of (two) fuel cells 1-2, 1-3, the fuel cell 1- having the lowest open circuit voltage is selected.
A plurality of (two) fuel cells 1-2, 1-3 on-off valves 7-2 are stopped so that the fuel off gas of the fuel cell 1-1 during power generation flows into the anode of No. 2 more. 2, 7-3 are configured to be controlled.

  The operation and action of the fuel cell system 200 of the present embodiment configured as described above will be described below with reference to FIGS. 3 and 4. The fuel cell system 200 shown in FIG. 3 executes the operation of the flowchart of FIG. 4 under the control of the controller 9.

  In the present embodiment, it is assumed that the fuel cell 1-1 is in the power generation operation, and the fuel cells 1-2 and 1-3 are in the power generation stop state. In the present embodiment, the open circuit voltage of the fuel cell 1-2 is lower than the open circuit voltage of the fuel cell 1-3.

  First, the discharge valve 6 of the common fuel gas discharge passage 5 is closed (S201). Next, open / close the on-off valve 7-1 of the fuel cell 1-1 during power generation operation and the on-off valves 7-2 and 7-3 of the two fuel cells 1-2 and 1-3 during power generation stoppage. And hold for 90 seconds (S202). Next, the on-off valves 7-2 and 7-3 of the two fuel cells 1-2 and 1-3 during power generation stop are closed, and the discharge valve 6 is opened for 30 seconds (S203). .

  Next, the on-off valve 7-1 of the fuel cell 1-1 during the power generation operation is closed and held for 10 minutes (S204). Next, the discharge valve 6 of the common fuel gas discharge passage 5 is closed (S205).

  Next, open the on-off valve 7-1 of the fuel cell 1-1 during the power generation operation, and the one with the lower open circuit voltage among the two fuel cells 1-2 and 1-3 during power generation stoppage The open / close valve 7-2 of the fuel cell 1-2 is opened and held for 90 seconds (S206).

  Next, the on-off valve 7-2 of the fuel cell 1-2 having a relatively low open circuit voltage during power generation stoppage is closed, and the discharge valve 6 is opened for 30 seconds (S207). Next, the on-off valve 7-1 of the fuel cell 1-1 during the power generation operation is closed, held for 10 minutes (S208), and the process returns to S201. In each step, immediately after the completion of the previous step, transition is made promptly without providing a waiting time.

  As described above, in the fuel cell system 200 according to the present embodiment, a plurality of fuel cell systems under power generation stop is performed based on the open circuit voltage immediately after the end of the power generation operation of the fuel cells 1-2 and 1-3 during power generation stop. Among the fuel cells 1-2 and 1-3, the on-off valve 7 of the fuel cell 1-1 during power generation operation so that the fuel off gas flows more into the fuel cell 1-2 having a relatively low open circuit voltage. The number of open / close valves 7-2 and 7-3 of the plurality of fuel cells 1-2 and 1-3 during power generation stoppage is controlled with respect to the number of times the open state is open.

  Therefore, it is possible to prevent the progress of the oxidation deterioration of the anode side catalyst layer of the fuel cell 1-2 having a large consumption of hydrogen during the power generation stop, and equalize the progress of the deterioration of the entire fuel cell during the power generation stop it can.

  In the present embodiment, the three fuel cells 1-1, 1-2, and 1-3 are disposed in the fuel cell system 200. However, three or more fuel cells may be used instead of three. That is, when three or more fuel cells are disposed in the fuel cell system 200, and at least two of the fuel cells are not generating power, and at least one or more fuel cells are generating power. The present invention is effective.

The holding time during which the on-off valve 7-1 of the fuel cell 1-1 is in the open state or the closed state at one time, the on-off valve of the fuel cell 1-2, 1-3 during the power generation stoppage The holding time in which the open / close state of 7-2, 7-3 is in the open state or the close state, and the hold time in which the discharge valve 6 is in the open state or the close state per time, fuel during power generation operation The setting of the number of times that the on-off valves 7-2 and 7-3 of the fuel cell 1-2 and 1-3 are open during the power generation stop with respect to the number of times that the on-off valve 7-1 of the cell 1-1 is open is Materials that make up the fuel cell, operating conditions (current value, generated voltage, required power generation output, supply gas amount), relationship between open circuit voltage immediately after the end of power generation operation and hydrogen consumption during power generation stop, hydrogen supply connection member Depending on the fuel cell structure design, such as the volume of the gas, the volume of the gas piping, the volume of the hydrogen channel of the separator, etc. It can be set as appropriate.

Third Embodiment
FIG. 5 is a block diagram showing a schematic configuration of a fuel cell system according to Embodiment 3 of the present invention. FIG. 6 is a flow chart showing a method of operating a fuel cell system according to Embodiment 3 of the present invention.

  The fuel cell system 300 of the third embodiment shown in FIG. 5 is obtained by replacing the controller 8 of the fuel cell system 100 of the first embodiment shown in FIG. In the fuel cell system 300 according to the third embodiment, the same components as those of the fuel cell system 100 according to the first embodiment may be denoted by the same reference numerals and redundant description may be omitted.

  In addition to the control similar to the controller 8 of the fuel cell system 100 of Embodiment 1, the controller 10 of the fuel cell system 300 of Embodiment 3 includes, for example, the power generation operation of at least one fuel cell 1-2. During that time, at least two fuel cells 1-1 and 1-3 are stopping power generation, and the time elapsed since the fuel cell 1-1 stopped power generation is the time elapsed since the fuel cell 1-3 stopped power generation If it is longer than the time, of the plurality (two) of fuel cells 1-1 and 1-3 during power generation suspension, the fuel cell 1-1 having the longest elapsed time since the power generation is stopped So that more fuel off-gas from the fuel cell 1-2 during power generation flows into the anode of the plurality of (two) fuel cells 1-1 and 1-3 during power generation stop. It is configured to control 1, 7-3.

  The operation and action of the fuel cell system 300 of the present embodiment configured as described above will be described below with reference to FIGS. 5 and 6. The fuel cell system 300 shown in FIG. 5 executes the operation of the flowchart of FIG. 6 under the control of the controller 10.

  In the present embodiment, it is assumed that the fuel cell 1-2 is in the power generation operation and the fuel cells 1-1 and 1-3 are in the power generation stop state. Further, in the present embodiment, it is assumed that the elapsed time after the fuel cell 1-1 stops generating power is longer than the elapsed time after the fuel cell 1-3 stops generating power.

  First, the discharge valve 6 of the common fuel gas discharge passage 5 is closed (S301). Next, open / close the on-off valve 7-2 of the fuel cell 1-2 in the power generation operation and the on-off valves 7-1 and 7-3 of the two fuel cells 1-1 and 1-3 in the power generation stop state. And hold for 90 seconds (S302). Next, the on-off valves 7-1 and 7-3 of the two fuel cells 1-1 and 1-3 during power generation stop are closed, and the discharge valve 6 is opened for 30 seconds (S303) .

  Next, the on-off valve 7-2 of the fuel cell 1-2 in the power generation operation is closed, and held for 10 minutes (S304). Next, the discharge valve 6 of the common fuel gas discharge passage 5 is closed (S305). Next, the on-off valve 7-2 of the fuel cell 1-2 in the power generation operation is opened, and the power generation is stopped while the power generation is stopped. The valve 7-1 is opened and held for 90 seconds (S306).

Next, the on-off valve 7-1 of the fuel cell 1-1 having a relatively longer elapsed time after the generation stoppage during the generation stoppage is closed and the discharge valve 6 is opened for 30 seconds. (S307).
Next, the on-off valve 7-2 of the fuel cell 1-2 in the power generation operation is closed, held for 10 minutes (S308), and the process returns to S301. In each step, immediately after the completion of the previous step, transition is made promptly without providing a waiting time.

  As described above, in the fuel cell system 300 according to the present embodiment, power generation is stopped based on the length of time elapsed from the power generation stop of the fuel cells 1-1 and 1-3 during power generation stop. Of the plurality of fuel cells 1-1 and 1-3, the power generation operation is being performed so that more fuel off gas flows into the fuel cell 1-1 having a relatively longer elapsed time since power generation is stopped. The on-off valves 7-1 and 7-3 of the plurality of fuel cells 1-1 and 1-3 being stopped during the generation of electricity are open with respect to the number of times the on-off valve 7 of the fuel cell 1-2 is open. Control the number of times.

  Therefore, it is possible to prevent the progress of the oxidation deterioration of the anode catalyst layer of the fuel cell 1-1 having a large consumption of hydrogen during the power generation stop, and make uniform the progress of the deterioration of the entire fuel cell during the power generation stop. it can.

  In the present embodiment, the three fuel cells 1-1, 1-2, and 1-3 are disposed in the fuel cell system 300. However, three or more fuel cells may be used instead of three. That is, when three or more fuel cells are disposed in the fuel cell system 300 and at least two or more of the fuel cells are not generating power, and at least one or more fuel cells are generating power. The present invention is effective.

  The holding time during which the on-off valve 7-2 of the fuel cell 1-2 is in the open state or the closed state at one time, the on-off valve of the fuel cell 1-1, 1-3 during the power generation stoppage 7-1 and 7-3 hold the open time or closed state at one time, and hold time the discharge valve 6 open and close state at one time, fuel during power generation operation The setting of the number of times that the on-off valves 7-1 and 7-3 of the fuel cell 1-1 and 1-3 are open during power generation stop with respect to the number of times that the on-off valve 7-2 of the battery 1-2 is open is Materials that make up the fuel cell, operating conditions (current value, generated voltage, required power generation output, supply gas amount), relationship between open circuit voltage immediately after the end of power generation operation and hydrogen consumption during power generation stop, hydrogen supply connection member Depending on the fuel cell structure design, such as the volume of the gas, the volume of the gas piping, the volume of the hydrogen channel of the separator, etc. It can be set as appropriate.

  As described above, the fuel cell system according to the present invention and the method of operating the same supply the fuel off gas periodically discharged to the outside from the fuel cell during power generation operation to the anode of the fuel cell during power generation suspension to generate power. Since it is possible to prevent the deterioration of the power generation efficiency of the entire fuel cell system while preventing the oxidation deterioration of the catalyst layer of the anode of the fuel cell during stoppage, for example, a driving source of a mobile body such as an automobile, A fuel cell comprising a plurality of polymer electrolyte fuel cells provided with a fuel gas circulation path, which is used for a generation system or the like, and operated such that the fuel cell in power generation and the fuel cell in power generation coexistence It can be applied to applications such as systems.

1-1, 1-2, 1-3 Fuel cell 2-1, 2-2, 2-3 Fuel gas supply path 3-1, 3-2, 3-3 Fuel gas circulation path 4-1, 4-2 , 4-3 Fuel gas discharge path 5 Common fuel gas discharge path 6 Discharge valve 7-1, 7-2, 7-3 On-off valve 8, 9, 10 Controller 100, 200, 300 Fuel cell system

Claims (6)

With multiple fuel cells,
A fuel gas supply passage provided individually for each of the plurality of fuel cells and for supplying a fuel gas to the anode of the fuel cell;
A fuel gas circulation path which is individually provided for each of a plurality of the fuel cells and returns unused fuel gas discharged from the anode of the fuel cell to the fuel gas supply path as the fuel gas;
A fuel gas discharge path branched from a plurality of the fuel gas circulation paths and discharging the fuel gas of the fuel gas circulation path;
A common fuel gas discharge path whose one end is in communication with the downstream end of the plurality of fuel gas discharge paths and whose other end is open to the atmosphere;
A normally-closed on-off valve individually provided for each of the plurality of fuel gas discharge paths to open and close the fuel gas discharge path;
A normally open discharge valve provided in the common fuel gas discharge path to open and close the common fuel gas discharge path;
A controller,
A fuel cell system comprising:
The controller
When opening the on-off valve corresponding to the fuel cell during at least one power generation operation while the power generation of the at least one fuel cell is stopped, the discharge valve is closed and then the at least one unit is closed Opening the open / close valve corresponding to the fuel cell in the power generation operation and the open / close valve corresponding to the fuel cell in the at least one power generation suspension state, and the fuel at the After a predetermined time has elapsed since the open / close valve corresponding to the battery is opened, the open / close valve corresponding to the fuel cell in a state where the power generation is stopped is returned to the closed state, and the discharge valve is opened. Closing the on-off valve corresponding to the fuel cell in the at least one power generation operation after returning the on-off valve corresponding to the fuel cell in the at least one power generation stop state to the close state Control is performed to the fuel cell system. The controller
At least one of the fuel cells is stopping power generation during the power generation operation of at least one of the fuel cells, and the consumption of the fuel gas during power generation suspension differs among the plurality of fuel cells stopping power generation. in case of,
Among the plurality of fuel cells under power generation stop, the plurality of fuels under power generation stop so that the fuel gas flows more into the anode of the fuel cell that consumes a large amount of fuel gas. The fuel cell system according to claim 1, which controls the on-off valve of a cell. The controller
In a case where at least two of the fuel cells are in a power generation suspension state during power generation operation of at least one of the fuel cells, and a plurality of the fuel cells in the power generation suspension state have different open circuit voltages immediately after the power generation operation ends. Is
Among the plurality of fuel cells under power generation stop, a plurality of fuel cells under power generation stop so that more fuel gas flows into the anode of the fuel cell having a low open circuit voltage immediately after the end of the power generation operation. The fuel cell system according to claim 1, wherein the on-off valve of the fuel cell is controlled. The controller
In a case where at least two of the fuel cells are in a power generation stop during the power generation operation of at least one of the fuel cells, and a plurality of the fuel cells in the power generation stop have different elapsed times from the power generation stop. Is
Among the plurality of fuel cells under power generation stop, a plurality of fuel cells under power generation stop so that more fuel gas flows into the anode of the fuel cell having a long elapsed time since the power generation stop. The fuel cell system according to claim 1, wherein the on-off valve of the fuel cell is controlled. The controller controls the number of times the on-off valve of the fuel cell in an open state is open while the on-off valve of the fuel cell is in an open state relative to the number of times the on-off valve of the fuel cell is open in a power generation operation. The fuel cell system according to any one of to 4. With multiple fuel cells,
A fuel gas supply passage provided individually for each of the plurality of fuel cells and for supplying a fuel gas to the anode of the fuel cell;
A fuel gas circulation path which is individually provided for each of a plurality of the fuel cells and returns unused fuel gas discharged from the anode of the fuel cell to the fuel gas supply path as the fuel gas;
A fuel gas discharge path branched from a plurality of the fuel gas circulation paths and discharging the fuel gas of the fuel gas circulation path;
A common fuel gas discharge path whose one end is in communication with the downstream end of the plurality of fuel gas discharge paths and whose other end is open to the atmosphere;
A normally-closed on-off valve individually provided for each of the plurality of fuel gas discharge paths to open and close the fuel gas discharge path;
A normally open discharge valve provided in the common fuel gas discharge path to open and close the common fuel gas discharge path;
A method of operating a fuel cell system comprising
When opening the on-off valve corresponding to the fuel cell during at least one power generation operation while the power generation of the at least one fuel cell is stopped, the discharge valve is closed and then the at least one unit is closed Opening the open / close valve corresponding to the fuel cell in the power generation operation and the open / close valve corresponding to the fuel cell in the at least one power generation suspension state, and the fuel at the After a predetermined time has elapsed since the open / close valve corresponding to the battery is opened, the open / close valve corresponding to the fuel cell in a state where the power generation is stopped is returned to the closed state, and the discharge valve is opened. Closing the on-off valve corresponding to the fuel cell in the at least one power generation operation after returning the on-off valve corresponding to the fuel cell in the at least one power generation stop state to the close state To method of operating a fuel cell system.

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