JP2019114345A - Fuel cell system - Google Patents

Abstract

To provide a fuel cell system capable of restraining power consumption while guaranteeing safety property.SOLUTION: A fuel cell system includes a fuel cell generating electric power by electrochemical reaction of fuel gas supplied to the anode and oxidant gas supplied to the cathode, an anode off-gas exhaust path for exhausting anode off-gas exhausted from the anode of the fuel cell, a purge valve provided in the anode off-gas exhaust path, a first air supply unit supplying the air for diluting the anode off-gas to the anode off-gas exhaust path, and a controller. The controller controls the first air supply unit to supply more air, when bringing the purge valve into an open state at the time other than the electricity generation time of the fuel cell, than the air when bringing the purge valve into open state at the time of electricity generation, to the anode off-gas exhaust path.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a fuel cell system, and more particularly to a fuel cell system that discharges anode off gas from the anode of the fuel cell.

  A configuration has been proposed in which the exhaust gas discharged from the fuel cell system is diluted with air and exhausted to the outside (for example, Patent Document 1).

  The fuel cell system disclosed in Patent Document 1 includes an exhaust gas for exhausting an anode off gas (anode purge gas), a heat medium (cooling water) circulating through the fuel cell to cool the fuel cell, and A radiator for cooling the heat medium and a radiator fan for increasing the flow rate (volume flow rate) of air passing through the radiator are provided. The air flow generated by the rotation of the radiator fan passes through the radiator and is then guided out of the storage case through the guide pipe. The end of the exhaust weir and the outlet of the guide pipe are provided adjacent to each other, and the anode off gas exhausted from the exhaust weir can be diffused by the air flow introduced through the guide pipe.

  In such a configuration, in the fuel cell system disclosed in Patent Document 1, the radiator fan is controlled to rotate at the maximum number of rotations for a predetermined time immediately after the start of the fuel cell, and Control so that the flow rate of the heat transfer medium is reduced. By performing such control, the fuel cell system disclosed in Patent Document 1 can reduce the hydrogen concentration in the discharged anode off gas in the anode purge performed immediately after the start of the fuel cell.

JP, 2011-65903, A

  However, in the prior art disclosed in Patent Document 1 described above, the radiator fan is controlled to rotate at the maximum rotation number for a predetermined time immediately after the start of the fuel cell, and the anode off gas is diluted. There is a possibility that air of more than the required flow rate may be supplied. Therefore, there is a problem that the amount of power consumed for rotating the radiator fan becomes large when the anode off gas is diluted at the start of the fuel cell.

  The present invention provides, as one example, a fuel cell system capable of suppressing power consumption while securing safety.

  One aspect (aspect) of a fuel cell system according to the present invention is a fuel cell that generates electric power by an electrochemical reaction between a fuel gas supplied to an anode and an oxidant gas supplied to a cathode, and an anode of the fuel cell Anode off gas discharge path for discharging the anode off gas, a purge valve provided in the anode off gas discharge path, and first air supply for supplying air for diluting the anode off gas to the anode off gas discharge path And the controller, when the purge valve is opened except when the fuel cell is generating electricity, when the purge valve is opened when the fuel cell is generating electricity The first air supplier is controlled to supply more air to the anode off gas exhaust path.

  The fuel cell system according to an aspect of the present invention has an effect that power consumption can be suppressed while securing safety.

It is a graph which shows the relationship between the flow volume of the anode off gas discharged | emitted by purge at the time of an electric power generation and starting, and the pressure difference between the predetermined position of an anode off gas discharge path, and atmospheric pressure. It is a figure showing typically an example of composition of a fuel cell system concerning an embodiment. It is a flowchart which shows an example of the operation | movement flow of air supply control implemented in the fuel cell system which concerns on embodiment of this invention. It is a figure which shows typically an example of a structure of the fuel cell system which concerns on the modification 1 of embodiment of this invention. It is a flowchart which shows an example of the operation | movement flow of air supply control implemented in the fuel cell system which concerns on the modification 1 of embodiment of this invention. It is a figure showing typically an example of the composition of the fuel cell system concerning modification 2 of an embodiment of the present invention. It is a flowchart which shows an example of the operation | movement flow of air supply control implemented in the fuel cell system which concerns on the modification 2 of embodiment of this invention. It is a figure showing typically an example of the composition of the fuel cell system concerning modification 3 of an embodiment of the present invention. It is a flowchart which shows an example of the operation | movement flow of air supply control implemented in the fuel cell system which concerns on the modification 3 of embodiment of this invention. It is a figure which shows typically an example of a structure of the fuel cell system which concerns on the modification 4 of embodiment of this invention. It is a flowchart which shows an example of the operation | movement flow of air supply control implemented in the fuel cell system which concerns on the modification 4 of embodiment of this invention.

(The process of obtaining one form of the present invention)
At the time of power generation of the fuel cell, an excess fuel gas (hydrogen) is supplied to the anode side of the fuel cell stack more than the consumption amount necessary for power generation. Then, an anode off gas, which is a mixture of hydrogen which has not been used for power generation, water vapor generated by power generation, and nitrogen which has entered from the cathode through the electrolyte membrane, is discharged from the fuel cell stack.

  Here, as a method of supplying the fuel gas (hydrogen) to the anode in the fuel cell, there are a dead end method and a circulation supply method. For example, in a dead-end fuel cell, the outlet of the anode is sealed, and the amount of hydrogen supplied is reduced by supplying only the amount of hydrogen necessary for power generation of the fuel cell. Further, in the circulation supply system, hydrogen is supplied to the anode of the fuel cell stack, the anode off gas discharged from the fuel cell stack is returned to the inlet side of the fuel cell stack, and the fuel is supplied to the fuel cell stack again with the newly supplied hydrogen. Supply. In this method, nitrogen is accumulated over time in the anode path. Therefore, it is necessary to purge the circulation path at a predetermined timing in order to discharge nitrogen. Specifically, an anode off gas discharge path branched from the circulation path and a purge valve provided in the anode off gas discharge path are provided, and by opening the purge valve at a predetermined timing, the anode off gas in the atmosphere through the anode off gas discharge path Release it.

  When the anode off gas is discharged through the anode off gas discharge path, the anode off gas can not be discharged to the atmosphere as it is, and the anode off gas is mixed with air to make the hydrogen concentration in the anode off gas smaller than the explosion limit. Need to be lowered. For example, the inventors of the present invention obtained the following findings as a result of intensive studies on the configuration in which the anode off gas is purged at a predetermined timing in such a circulation supply system and the like.

  That is, as shown in FIG. 1, as the pressure difference between the pressure of the anode off gas flowing upstream of the purge valve in the anode off gas discharge path and the atmospheric pressure becomes larger, the anode off gas is discharged. It has been found that the volume (volume flow rate) per unit time of the anode off gas discharged through the route increases. Furthermore, it was noticed that the volume flow rate of the anode off gas discharged through the anode off gas discharge path also differs depending on the temperature of the anode off gas flowing through the anode off gas discharge path. Hereinafter, the volumetric flow rate of the anode off gas is simply referred to as the flow rate of the anode off gas.

  FIG. 1 is a graph showing the relationship between the flow rate of the anode off gas discharged by purge at the time of power generation and at the time of startup, and the pressure difference between a predetermined position of the anode off gas discharge path and the atmospheric pressure. In the experiment shown in FIG. 1, the predetermined position is the upstream side of the purge valve in the anode off gas discharge path in the flow direction of the anode off gas.

  Further, in FIG. 1, the solid line shows the relationship between the above-described pressure difference and the flow rate of the anode off gas at startup, and the broken line shows the relationship between the above-described pressure difference and the flow rate of the anode off gas during power generation. The temperature of the anode off gas discharged by the purge at the time of start-up was a temperature according to the normal temperature, and was 27 ° C. here. On the other hand, the temperature of the anode off gas discharged by the purge at the time of power generation is a temperature according to the fuel cell stack temperature. Here, the anode off-gas temperature was defined from the temperature of the heat medium for cooling the fuel cell stack which is correlated with the fuel cell stack temperature. Specifically, the anode off-gas temperature is a temperature when the temperature of the heat medium flowing into the fuel cell stack is 57 ° C. and the temperature of the heat medium discharged from the fuel cell stack is 71 ° C. ° C.

  As shown in FIG. 1, it was found that the flow rate of the anode off gas discharged to the atmosphere increases as the pressure difference increases, both at the time of power generation and startup of the fuel cell. Also, even if the pressure difference is the same, the flow rate of the anode off gas discharged by the purge is smaller when the temperature of the anode off gas is higher than at the time of start-up as in the fuel cell power generation. I understand. This is discharged by the purge during power generation rather than the anode off gas discharged by the purge when the temperature of the fuel cell is lower than during power generation (e.g., other than during power generation such as at start-up or shutdown) The anode off gas has a higher dew point and a higher proportion of water vapor contained, in other words, a lower proportion of hydrogen.

  That is, hydrogen has a smaller pressure loss when passing through the purge valve than steam. For this reason, the anode off gas exhausted by the purge at the time of power generation becomes harder to flow than the anode off gas exhausted by the purge at the time of startup. As a result, the flow rate of the anode off gas discharged by the purge at the time of power generation is discharged by the purge when the temperature of the fuel cell is lower than at the time of power generation (e.g., other than the time of power generation such as startup or shutdown). Was found to be smaller than the flow rate of the anode off gas.

  As described above, the inventors of the present invention have determined that the flow rate of the anode off gas discharged through the purge valve is based on the pressure difference between the anode off gas flowing through the upstream side of the purge valve and the atmosphere and / or the temperature of the anode off gas. Found that it can be estimated. For example, when the pressure difference between the pressure of the anode off gas flowing upstream of the purge valve and the pressure of the atmosphere is constant and the temperature of the anode off gas fluctuates, the anode off gas discharged by purge is purged based on the temperature of the anode off gas. The flow rate can be estimated. Conversely, if the temperature of the anode off gas is constant and the pressure difference between the anode off gas flowing through the upstream side of the purge valve and the atmosphere fluctuates, the flow rate of the anode off gas discharged by purge is determined based on the pressure difference. It can be estimated. In addition, when the temperature of the anode off gas and the pressure difference between the anode off gas flowing through the upstream side of the purge valve and the atmosphere both fluctuate, the anode off gas discharged by the purge based on the temperature of the anode off gas and the pressure difference. Flow rate can be estimated.

  Based on the above-described findings, the present inventors diligently studied the fuel cell system disclosed in Patent Document 1. Specifically, in the fuel cell system of Patent Document 1, the radiator fan (the fan for a heat exchanger) is driven at the maximum number of revolutions when the anode off gas is discharged. Thus, the anode off gas exhausted from the exhaust gas can be diffused by the air by the radiator fan.

  However, when the radiator fan is driven at the maximum rotation speed, not only the temperature of the heat medium (cooling water) is excessively lowered by air generated by the rotation of the radiator fan, but also the amount of power consumed by the radiator fan is increased. In the fuel cell system disclosed in Patent Document 1, with regard to the problem that the temperature of the heat medium falls too low, circulation is performed so as to reduce the flow rate of the circulating heat medium while the radiator fan is driven at the maximum rotation speed. It copes by controlling the rotation of the pump. However, the increase in power consumption is not considered.

  Therefore, in the case of the configuration in which the anode off gas is mixed with air to be diluted and discharged, the inventors of the present invention have the flow rate of air supplied at times other than the time of power generation such as at startup. I realized that I needed to control more. In particular, considering the difference in hydrogen concentration in the anode off gas caused by the difference between the temperature of the anode off gas at the time of power generation and the temperature of the anode off gas at the time of power generation, it is more appropriate than the time of power generation It has been found that supplying air, which increases by a large flow rate, to the anode off gas discharge path is important for safely diluting the anode off gas and discharging it while suppressing the amount of power consumed in the fuel cell system .

  Then, the present inventors came to this invention, as a result of repeating earnest examination regarding this problem. And the present invention provides the aspect shown below.

  According to a first aspect of the present invention, there is provided a fuel cell system that generates electric power by an electrochemical reaction between a fuel gas supplied to an anode and an oxidant gas supplied to a cathode. An anode off gas discharge path for discharging an anode off gas discharged from an anode of the fuel cell; a purge valve provided in the anode off gas discharge path; and air for diluting the anode off gas. The fuel cell system further includes a first air supply device for supplying to a path, and a controller, wherein the controller causes the fuel cell to generate electricity when the purge valve is opened except when the fuel cell is generating electricity. Control the first air supply to supply more air to the anode off gas exhaust path than when the purge valve is open

  Here, other than the time of power generation of the fuel cell may be, for example, the time of startup of the fuel cell. The start-up time is a period from when a start-up command is input to the fuel cell system to when the temperature of the fuel cell (the stack temperature of the fuel cell) rises to a predetermined temperature during power generation (during steady operation). The predetermined temperature at the time of power generation (during steady operation) is preset according to the configuration of the fuel cell stack. In addition, there is a period other than the start time, in which the temperature of the fuel cell is lower than that during power generation, and such a period can be included in the period other than power generation. As such a period, for example, the standby operation or stop operation of the fuel cell may be mentioned. In the standby operation, the temperature of the fuel cell has not reached the temperature at the time of power generation, and the fuel cell does not supply power to the external load. The stop operation is an operation state in which the power output of the fuel cell is reduced while being reduced at a constant rate of change.

  According to the above configuration, when the purge valve is opened other than at the time of power generation, the air volume of the first air supply can be increased more than when the purge valve is opened at the time of power generation. The air flow rate sufficient for diluting the anode off gas can be secured except during power generation, such as at the time of start-up, which is more than at the time of power generation. In addition, when air is supplied to the anode off gas discharge path when the purge valve is open except during power generation, the first air supply device is not driven at the maximum rotation speed as in the above-described prior art. An increase in power consumption can be suppressed.

  Therefore, the fuel cell system according to the present invention has an effect that power consumption can be suppressed while securing safety.

  The fuel cell system according to the second aspect of the present invention is, in the first aspect described above, provided in a heat medium circulation path through which a heat medium for recovering heat generated by the fuel cell is circulated, and the heat medium circulation path. And the first air supplier is configured to supply the air to the heat exchanger and to supply the air supplied to the heat exchanger to the anode off gas exhaust path. It may be.

  According to the above configuration, the first air supplier doubles as an air supplier supplying air to dilute the anode off gas and an air supplier supplying air to the heat exchanger to cool the heat medium. Can.

  Therefore, the fuel cell system according to the second aspect of the present invention can reduce the manufacturing cost and increase the degree of freedom of the layout in the fuel cell system.

  In the fuel cell system according to the third aspect of the present invention, in the second aspect, the controller controls the anode off gas based on a first temperature indicating a temperature of a heat medium circulating in the heat medium circulation path. The flow rate of the air supplied to the discharge path may be calculated, and the first air supplier may be controlled to operate according to the calculated flow rate of the air.

  Here, the temperature of the heat transfer medium, which is indicated as the first temperature, is correlated with the temperature of the fuel cell and the temperature of the anode off gas exhausted from the fuel cell. Further, as described in “How the Invention Has Obtained One Embodiment of the Present Invention”, the temperature of the anode off gas correlates with the flow rate of the anode off gas discharged from the anode off gas discharge path.

  According to the above configuration, the controller can replace the temperature of the anode off gas exhausted from the fuel cell with the first temperature indicating the temperature of the heat medium. Further, since the controller can estimate the flow rate of the anode off gas discharged through the anode off gas discharge path from the first temperature, it can determine the flow rate of air necessary for supplying the anode off gas discharge path. .

  Thus, the controller determines the flow rate of air necessary to dilute the anode off gas without directly detecting the temperature of the anode off gas, and operates the first air supply to supply it to the anode off gas discharge path. It can be done.

  Therefore, in the fuel cell system according to the third aspect of the present invention, the flow rate of air required according to the temperature of the anode off gas can be supplied to the anode off gas discharge path, so consumption by the first air supplier. Power consumption can be reduced.

  The first temperature is obtained, for example, from the flow rate of the heat medium determined from the rotational speed of a circulation pump or the like that circulates the heat medium in the heat medium circulation path and the calorific value of the fuel cell determined from the power generation state of the fuel cell. You may get it.

  In the fuel cell system according to the fourth aspect of the present invention, in the second aspect described above, the controller is based on the pressure of the anode off gas flowing upstream of the purge valve in the anode off gas discharge path. The flow rate of the air supplied to the anode off gas discharge path may be calculated, and the first air supplier may be controlled to operate according to the calculated flow rate of the air.

  The magnitude of the pressure difference between the anode off gas flowing on the upstream side of the purge valve in the anode off gas discharge path and the outside of the anode off gas discharge path (in the air) is as described above. As mentioned above, it correlates with the flow rate of the anode off gas discharged through the anode off gas discharge path. The upstream side of the purge valve means a portion located upstream of the purge valve in the flow direction of the anode off gas.

  According to the above configuration, the controller can estimate the flow rate of the anode off gas discharged through the anode off gas discharge path from the pressure of the anode off gas flowing upstream of the purge valve in the anode off gas discharge path. Thus, the controller can determine the flow rate of air required to supply the anode off gas discharge path.

  Therefore, in the fuel cell system according to the fourth aspect of the present invention, the required flow rate of air is determined according to the pressure of the anode off gas flowing on the upstream side of the purge valve in the anode off gas discharge path. Thus, the amount of power consumed by the first air supplier can be reduced.

  The pressure of the anode off gas flowing through the upstream side of the purge valve may be obtained, for example, from the output of a motor that operates an impeller such as a booster pump that supplies fuel gas to the anode.

  The fuel cell system according to a fifth aspect of the present invention is the fuel cell system according to the second aspect described above, wherein the controller is based on a second temperature that is a temperature of the anode off gas flowing through the anode off gas discharge path. The flow rate of the air supplied to the anode off gas discharge path may be determined, and the first air supplier may be controlled to operate according to the determined flow rate of the air.

  The temperature of the anode off gas flowing through the anode off gas discharge path correlates with the flow rate of the anode off gas discharged through the anode off gas discharge path, as described above in the section "Background to achieving one embodiment of the present invention".

  According to the above configuration, the controller can obtain the flow rate of the anode off gas discharged through the anode off gas discharge path from the temperature of the anode off gas flowing through the anode off gas discharge path. The flow rate of the air can be obtained.

  Therefore, in the fuel cell system according to the fifth aspect of the present invention, the flow rate of air required according to the temperature of the anode off gas flowing through the anode off gas discharge path can be supplied to the anode off gas discharge path. The amount of power consumed by the first air supply can be reduced.

  The fuel cell system according to a sixth aspect of the present invention further comprises a second air supplier for supplying the air to the anode off gas discharge path according to the first aspect described above, wherein the controller at least includes the fuel When the purge valve is opened except when the battery generates power, more air is supplied to the anode off gas discharge path when the fuel cell generates electricity than when the purge valve is opened. It may be controlled to operate at least one of the first air supplier and the second air supplier.

  According to the above configuration, the fuel cell system according to the sixth aspect of the present invention further includes the second air supplier, so operating at least one of the second air supplier and the first air supplier. The required flow rate of air can be supplied to the anode off gas discharge path.

  Therefore, in each of the first air supply device and the second air supply device, even if it is not possible to supply the required flow of air to the anode off gas discharge path, operating both of the necessary flow of air by operating both of them. It can be supplied to the anode off gas discharge path.

  For this reason, it is not necessary to provide in advance a high-performance air supply device capable of supplying air having a flow rate larger than that required at the time of power generation of the fuel cell, and the manufacturing cost can be suppressed.

  The fuel cell system according to a seventh aspect of the present invention is, in the sixth aspect described above, provided with a heat medium circulation path through which a heat medium for recovering heat generated by the fuel cell circulates, and the heat medium circulation path. And the first air supplier supplies the air to the heat exchanger and supplies the air supplied to the heat exchanger to the anode off gas exhaust path. It may be.

  According to the above configuration, the first air supplier supplies the air to supply the air to dilute the anode off gas, and the air supplier supplies the air to the heat exchanger to cool the heat medium and control the temperature. Can also serve as a container.

  Therefore, the fuel cell system according to the seventh aspect of the present invention can reduce the manufacturing cost and increase the degree of freedom of the layout in the fuel cell system.

  The fuel cell system according to an eighth aspect of the present invention is the fuel cell system according to the seventh aspect described above, wherein the controller controls the anode off gas based on a first temperature indicating a temperature of a heat medium circulating in the heat medium circulation path. The flow rate of the air supplied to the discharge path is calculated, and at least one of the first air supply device and the second air supply device is controlled to operate according to the calculated flow rate of the air. It may be.

  According to the above configuration, the controller can replace the temperature of the anode off gas exhausted from the fuel cell with the first temperature indicating the temperature of the heat medium. In addition, since the controller can estimate the flow rate of the anode off gas discharged through the anode off gas discharge path from the first temperature, the controller can determine the flow rate of air required to be supplied to the anode off gas discharge path.

  Thus, the controller determines the flow rate of air required to dilute the anode off gas directly without detecting the temperature of the anode off gas, and at least one of the first air supply and the second air supply. One can be operated and supplied to the anode off gas exhaust path.

  Therefore, in the fuel cell system according to the eighth aspect of the present invention, the required flow rate of air can be determined according to the temperature of the anode off gas, and can be supplied to the anode off gas discharge path. And the amount of power consumed by the second air supply device can be reduced.

  The fuel cell system according to a ninth aspect of the present invention is the fuel cell system according to the seventh aspect described above, wherein the controller is based on the pressure of the anode off gas flowing upstream of the purge valve in the anode off gas discharge path. The flow rate of the air supplied to the anode off gas discharge path is calculated, and control is performed to operate at least one of the first air supply device and the second air supply device according to the calculated flow rate of the air. The configuration may be

  According to the above configuration, the controller can estimate the flow rate of the anode off gas discharged through the anode off gas discharge path from the pressure of the anode off gas flowing upstream of the purge valve in the anode off gas discharge path. Thus, the controller can determine the flow rate of air required to supply the anode off gas discharge path.

  Therefore, in the fuel cell system according to the ninth aspect of the present invention, the required flow rate of air is determined according to the pressure of the anode off gas flowing upstream of the purge valve and supplied to the anode off gas discharge path. As a result, the amount of power consumed by the first air supplier and the second air supplier can be reduced.

  The fuel cell system according to a tenth aspect of the present invention is the fuel cell system according to the seventh aspect described above, wherein the controller is based on a second temperature that is a temperature of the anode off gas flowing through the anode off gas discharge path. The flow rate of the air supplied to the anode off gas exhaust path is determined, and at least one of the first air supply and the second air supply is controlled to operate according to the determined flow rate of the air. It may be a configuration.

  According to the above configuration, the controller can obtain the flow rate of the anode off gas discharged through the anode off gas discharge path from the temperature of the anode off gas flowing through the anode off gas discharge path. The flow rate of the air can be obtained.

  Therefore, in the fuel cell system according to the tenth aspect of the present invention, the flow rate of air required according to the temperature of the anode off gas flowing through the anode off gas discharge path can be supplied to the anode off gas discharge path. The amount of power consumed by the first air supplier and the second air supplier can be reduced.

  The fuel cell system according to an eleventh aspect of the present invention is, in the above third or eighth aspect, provided with a first temperature detector provided in the heat medium circulation path for detecting the first temperature. It may be

  According to the above configuration, since the first temperature detector is provided, the first temperature indicating the temperature of the heat medium circulating in the heat medium circulation path can be detected. Furthermore, the temperature of the anode off gas can be obtained from the first temperature, and the flow rate of the anode off gas discharged from the anode off gas discharge path can be estimated based on the obtained temperature of the anode off gas.

  Thus, the first temperature detector functions as a detector for performing temperature control of the heat medium in the heat medium circulation path, and obtains information for determining the air flow rate to be supplied to the anode off gas discharge path. Can function as a detector of Therefore, in the fuel cell system according to the eleventh aspect of the present invention, a detector for performing temperature control of the heat medium, and a detection for obtaining information for obtaining an air flow rate to be supplied to the anode off gas discharge path. There is no need to separately provide the Therefore, an appropriate flow rate of air can be supplied to the anode off gas exhaust path without increasing the manufacturing cost.

  The fuel cell system according to a twelfth aspect of the present invention is the pressure detector according to the fourth or ninth aspect, wherein the pressure detector detects the pressure of the anode off gas flowing upstream of the purge valve in the anode off gas discharge path. May be provided.

  According to the above configuration, since the pressure detector is provided, the pressure of the anode off gas flowing on the upstream side of the purge valve in the anode off gas discharge path can be detected. Furthermore, the required air flow rate to be supplied to the anode off gas exhaust path can be determined from the detected pressure.

  Therefore, in the fuel cell system according to the twelfth aspect of the present invention, even if the pressure of the anode off gas flowing through the anode off gas discharge path fluctuates, the fuel cell system is appropriately determined by determining the flow rate of the anode off gas based on the detected pressure. A flow of air can be supplied to the anode off gas exhaust path.

  The fuel cell system according to a thirteenth aspect of the present invention may be configured to include a second temperature detector for detecting the second temperature in the fifth or tenth aspect described above.

  According to the above configuration, since the second temperature detector is provided, the temperature of the anode off gas flowing through the anode off gas discharge path can be detected. Furthermore, it is possible to accurately determine the required air flow rate to be supplied to the anode off gas discharge path from the detected second temperature.

  Therefore, the fuel cell system according to the thirteenth aspect of the present invention determines the flow rate of the anode off gas based on the detected second temperature even if the temperature of the anode off gas flowing through the anode off gas discharge path changes. An appropriate flow of air can be supplied to the anode off gas exhaust path.

  Hereinafter, specific examples of the embodiment will be described with reference to the drawings.

(Embodiment)
[Fuel cell system configuration]
First, the configuration of a fuel cell system 100 according to the embodiment will be described with reference to FIG. FIG. 2 is a view schematically showing an example of the configuration of the fuel cell system 100 according to the embodiment.

  As shown in FIG. 2, the fuel cell system 100 includes a fuel cell 1, an anode off gas discharge path 2, a purge valve 3, a first air supplier 4, and a controller 5.

  The fuel cell 1 generates electric power by an electrochemical reaction between the fuel gas supplied to the anode and the oxidant gas supplied to the cathode. The fuel cell 1 includes, for example, an electrolyte (not shown) and a plurality of single cells provided with a pair of electrodes (not shown) sandwiching the electrolyte, and a stack (not shown) in which these single cells are stacked is Prepare. In addition, as a fuel gas supplied to an anode, hydrogen etc. can be illustrated, for example. When the fuel gas is hydrogen, the anode off gas that is discharged through the anode is off hydrogen gas. In the fuel cell system 100 according to the embodiment of the present invention, fuel gas (hydrogen) is supplied from the fuel gas supply source (not shown) to the anode of the fuel cell 1 through the fuel gas supply path (not shown). . The fuel gas supply source can be exemplified by, for example, a fuel gas infrastructure, a fuel gas cylinder, etc., having a predetermined supply pressure.

  The fuel cell 1 may be of any type. In the fuel cell system 100 of the present embodiment, a polymer electrolyte fuel cell (PEFC) is described as an example of the fuel cell 1, but the present invention is not limited to this. Further, the fuel gas supply system in the fuel cell 1 may be a circulation supply system. In the case where the fuel gas is supplied by the circulation supply system, the anode off gas discharge path 2 is provided in communication with a circulation path (not shown) through which the anode off gas circulates.

  The anode off gas discharge path 2 is a flow path for discharging the anode off gas having passed through the anode of the fuel cell 1 to the atmosphere. The anode off gas discharge path 2 is provided with a purge valve 3. When the purge valve 3 is opened to open the anode off gas discharge path 2, the anode off gas is discharged to the atmosphere through the anode off gas discharge path 2. Ru. The purge valve 3 may have any configuration as long as the anode off gas exhaust passage 2 can be opened and closed. For example, the purge valve 3 may be an open / close valve that opens or closes the anode off gas exhaust path 2. Alternatively, the purge valve 3 may be a flow control valve (for example, a needle valve or the like) that enables the opening of the anode off gas discharge path 2 to be adjusted. The downstream end of the anode off gas discharge path 2 communicates with the atmosphere, and the purge valve 3 is used as a device for releasing the anode off gas into the atmosphere. In the case of the circulation supply system, while the purge valve 3 is in a closed state, impurities other than the fuel gas (hydrogen) increase with time in the anode off gas. As this impurity, for example, nitrogen leaking from the cathode of the fuel cell 1 through the electrolyte membrane to the anode can be exemplified. When the impurities in the anode off gas increase, the hydrogen concentration in the anode off gas decreases. Therefore, during the power generation of the fuel cell 1, by temporarily opening the purge valve 3, the anode off gas containing the impurities is transferred to the atmosphere. Release (purge). Thus, the concentration of impurities in the anode off gas can be reduced, and the hydrogen concentration in the anode off gas can be recovered.

  The first air supplier 4 is a blower for supplying air to the anode off gas discharge path 2. The first air supplier 4 supplies the required amount of air to the anode off gas discharge path 2 in accordance with the flow rate of the anode off gas discharged from the anode off gas discharge path 2. In the fuel cell system 100 according to the embodiment of the present invention, the anode off gas and the air merge at the downstream side of the anode off gas discharge path 2 downstream of the purge valve 3 in the flow direction of the anode off gas, and the anode off gas is diluted. It is configured to be.

  Further, in the fuel cell system 100 according to the embodiment of the present invention, the relationship between the flow rate of air supplied to the anode off gas discharge path 2 and the flow rate of the anode off gas is the same as that in the mixture of air and anode off gas. The percentage of off gas is specified to be 1%. In the mixture of hydrogen and air, the lower limit of the explosion limit of hydrogen is 4%. Therefore, in the fuel cell system 100 according to the embodiment of the present invention, the anode off gas is regarded as hydrogen, and the ratio of the anode off gas to the supplied air is 1/4 (1%) of the lower limit of the hydrogen explosion limit. It prescribes in. The relationship between the flow rate of air supplied to the anode off gas discharge path 2 and the flow rate of the anode off gas is not limited to the above-described relationship, and the ratio of hydrogen contained in the mixture of the anode off gas and air Should be smaller than the lower limit of the explosion limit.

  The first air supplier 4 may be a suction type blower that draws air for diluting the anode off gas into the anode off gas discharge path 2 or is a spray type fan that sends air to the anode off gas discharge path 2. May be Further, the first air supply device 4 has a variable air volume supplied to the anode off gas discharge path 2 in accordance with a control instruction from the controller 5. The adjustment of the air volume may be performed, for example, by controlling the number of rotations of the motor that operates the impeller of the first air supply device 4. The first air supplier 4 may be a fan or another fan such as a compressor.

  The controller 5 controls various parts of the fuel cell system 100, and may have any configuration as long as it has a control function. For example, the controller 5 includes an arithmetic circuit (not shown) and a storage circuit (not shown) that stores a control program. For example, an MPU, a CPU, etc. can be exemplified as the arithmetic circuit. For example, a memory can be exemplified as the memory circuit. The controller 5 may be configured by a single controller that performs centralized control, or may be configured by a plurality of controllers that perform distributed control in cooperation with each other.

  The controller 5 controls the flow rate of the fuel gas and the flow rate of the oxidant gas supplied to the fuel cell based on the information such as the temperature of the fuel cell 1 and the power generation amount of the fuel cell 1, and the off gas discharged from the fuel cell The fuel gas supply (not shown) and the cathode gas supply can be controlled to adjust the flow rates of the anode off gas and the cathode off gas.

  Further, when the controller 5 controls the purge valve 3 to open in the anode off gas discharge path 2 at a predetermined timing, the air of the required flow rate is set to the anode off gas according to the operating state of the fuel cell 1. The first air supplier is controlled to be supplied to the discharge path 2. For example, when the controller 5 opens the purge valve 3 at the start of the fuel cell 1, the flow rate of air supplied to the anode off gas discharge path 2 is purged at the time of power generation of the fuel cell 1 (during steady operation). The first air supplier is controlled to be more than when the valve 3 is opened.

  When the purge valve 3 is opened in a period other than the above-described start-up period and in which the temperature of the fuel cell 1 is lower than that during power generation (during steady operation), the anode off gas is The first air supplier 4 is controlled so that the flow rate of air supplied to the discharge path 2 is greater than when the fuel cell 1 generates power (during steady operation) than when the purge valve 3 is opened. It may be done. Note that, as a period other than the time of power generation (during steady operation), for example, the time of startup can be mentioned. During start-up, the start-up command is input to the controller 5 of the fuel cell system 100 and the temperature of the fuel cell 1 (the stack temperature of the fuel cell) rises to a predetermined temperature during power generation (during steady operation) It is a period of The predetermined temperature at the time of power generation (during steady operation) is preset according to the configuration of the fuel cell stack, and can be, for example, 57 ° C. in the case of PEFC.

  Further, there is a period other than the start time, in which there is a period in which the temperature of the fuel cell 1 is lower than that in power generation (during steady operation), such a period is included in the period other than power generation. For example, there may be mentioned a standby operation or a stop operation of the fuel cell 1. In the standby operation, the temperature of the fuel cell 1 does not reach the temperature at the time of power generation (during steady operation), and the fuel cell 1 does not supply power to the external load. The stop operation is an operation state in which the power output of the fuel cell 1 is stopped while being reduced at a constant change rate.

  In the fuel cell system 100 according to the embodiment of the present invention, the flow rate of air supplied to the anode off gas discharge path 2 is, as described above, at least when the purge valve 3 is opened except when the fuel cell 1 generates electricity. The first air supply device 4 is controlled so that the amount is larger than when the purge valve 3 is opened during power generation of the fuel cell 1 (during steady operation).

  That is, as shown in FIG. 1, the flow rate of the anode off gas passing through the purge valve 3 and flowing through the anode off gas discharge path 2 is larger than the pressure of the anode off gas flowing upstream of the purge valve 3 in the anode off gas discharge path 2. It can be estimated by the pressure difference with the atmospheric pressure, and / or the temperature of the anode off gas. When the temperature of the fuel cell 1 is low and the temperature of the anode off gas is lowered accordingly, the proportion of water vapor contained in the anode off gas decreases because the dew point is low. Therefore, the proportion of hydrogen contained in the anode off gas is increased, the pressure loss when passing through the purge valve 3 is reduced, and the flow rate of the anode off gas is increased. Therefore, when the temperature of the anode off gas decreases, the flow rate of air required to dilute the anode off gas increases.

  The temperature of the anode off gas at the time of power generation of the fuel cell 1, the temperature of the anode off gas at times other than the power generation, and / or the pressure difference between the anode off gas flowing through the upstream side of the purge valve and the atmosphere The unit 5 may be configured to be able to set the flow rate of air according to the respective operating conditions based on the temperatures of these anode off gases. Then, the controller 5 may be configured to supply air of a flow rate set according to the operating state to the anode off gas discharge path 2 when the purge valve is in the open state.

  Although not particularly illustrated in FIG. 2, the fuel cell system 100 appropriately includes devices necessary for power generation of the fuel cell 1. For example, the fuel cell system 100 may include an oxidant gas supplier that supplies oxidant gas to the cathode of the fuel cell 1. As an oxidant gas, air can be illustrated, for example. When the oxidant gas is air, for example, a blower such as a blower or a sirocco fan can be exemplified as the oxidant gas supply device. The fuel cell system 100 may further include a humidifier for humidifying the fuel gas flowing through the fuel gas supply path. Also, if the supply pressure of the fuel gas supply source is higher than the required supply pressure (the supply pressure of the fuel gas) in the fuel cell system 100, the pressure of the fuel gas is reduced in the fuel gas supply path to set a constant supply pressure. A governor or the like may be provided.

[Air supply control]
Next, air supply control for supplying air to the anode off gas discharge path 2, which is performed when the purge valve 3 is opened in the fuel cell system 100 according to the embodiment of the present invention, will be described with reference to FIG. Do. FIG. 3 is a flow chart showing an example of the operation flow of air supply control implemented in the fuel cell system 100 according to the embodiment of the present invention.

  Note that each step of air supply control shown below can be realized, for example, by the arithmetic circuit of the controller 5 reading out the control program from the storage device and executing it.

  First, in step S11, the controller 5 determines whether or not the fuel cell 1 is in power generation. When it is determined that power is being generated ("Yes" in step S11), the controller 5 sets the flow rate of air supplied to the anode off gas discharge path 2 during power generation (S12). On the other hand, when it is determined that the fuel cell 1 is other than during power generation (for example, at start-up) ("No" in step S11), the controller 5 supplies the anode off gas discharge path 2 during operation other than during power generation. The flow rate of air is set (step S13).

  Note that the method of setting the flow rate of air in step S12 and step S13 can be determined using data estimated at the time of power generation of the fuel cell 1 or other than power generation (for example, at start-up). For example, as shown in FIG. 1, when the pressure difference between the anode off gas flowing through the upstream side of the purge valve 3 and the atmosphere is 3 kPa, supply to the anode off gas discharge path 2 at the time other than power generation The flow rate of the air is set to be about 2.5 times the flow rate of the air supplied to the anode off gas discharge path 2 at the time of power generation.

  Next, the controller 5 determines whether or not it is time to open the purge valve 3 (step S14). As described above, when the impurities in the anode off gas increase, the hydrogen concentration in the anode off gas decreases. Therefore, for example, in the configuration in which the fuel gas is supplied to the anode by the circulation supply system, it is necessary to temporarily open the purge valve 3 at appropriate timing during the power generation of the fuel cell 1.

  The timing at which the purge valve 3 is opened may be after the elapse of a predetermined period from when the purge valve 3 was opened last time. Alternatively, it may be timing when the controller 5 receives an instruction signal for instructing the purge valve 3 to open from the outside. In the latter case, for example, the controller 5 may be configured to receive an instruction signal as follows. That is, the fuel cell system 100 includes a hydrogen detector (not shown) for detecting the hydrogen concentration in the anode off gas, and when the hydrogen detector determines that the hydrogen concentration in the anode off gas becomes lower than a predetermined concentration, The instruction signal may be transmitted to the controller 5.

  On the other hand, when it is not the timing to open the purge valve 3 (“No” in step S14), the closed state of the purge valve 3 is maintained, and the determination of step S14 is repeated.

  When it is determined “Yes” in step S14, the controller 5 controls the first air supplier 4 so as to supply the air of the flow rate set in step S12 or step S13 to the anode off gas discharge path 2 (step S15). The controller 5 may be configured to control the first air supplier 4 as follows. That is, the fuel cell system 100 further includes a rotation number detector (not shown) for detecting the number of rotations of the impeller included in the first air supply device 4 or the number of rotations of the motor for operating the impeller. The controller 5 may control the first air supplier 4 by feedback control based on detection data detected by the detector.

  When the first air supplier 4 is controlled in this manner, the controller 5 controls the purge valve 3 to open it (step S16). As a result, the anode off gas is discharged (purged) from the anode off gas discharge path 2 to the atmosphere while being diluted by air. By this purge of the anode off gas, in the fuel cell system 100, the concentration of impurities in the anode off gas can be reduced, and the hydrogen concentration in the anode off gas can be recovered.

  Next, the controller 5 determines whether it is time to close the purge valve 3 (step S17). The timing at which the purge valve 3 is closed may be after the lapse of a predetermined period from when the purge valve 3 is opened. Alternatively, the timing may be such that the controller 5 receives an instruction signal instructing the closing of the purge valve 3 from the outside. In the latter case, for example, the controller 5 may be configured to receive an instruction signal as follows. That is, the fuel cell system 100 includes a hydrogen detector (not shown) for detecting the concentration of hydrogen in the anode off gas, and when the hydrogen detector determines that the concentration of hydrogen in the anode off gas becomes equal to or higher than the predetermined concentration, The instruction signal may be transmitted to the controller 5.

  On the other hand, if it is not time to close the purge valve 3 ("No" in step S17), the purge valve is maintained in the open state, and the determination in step S17 is repeated.

  On the other hand, when it is determined that the timing for closing the purge valve 3 has come (in the case of “Yes” in step S17), the controller 5 controls the purge valve 3 to close (step S18) , Control to stop the operation of the first air supply device 4 (step S19). And it returns to step S11 and repeats air supply control.

  In the fuel cell system 100, the operation of the first air supplier 4 is stopped in step S19. However, when the first air supplier 4 also functions as supplying the air to the anode off gas discharge path 2 such as cooling a member that generates heat during power generation, the operation of the first air supplier 4 is completely completed. Alternatively, the supply of air may be continued by reducing the flow rate of the air supplied.

  As described above, the fuel cell system 100 can appropriately release the anode off gas into the atmosphere in a state of being diluted with air by performing the air supply control.

(Modification 1)
[Device configuration]
Next, a fuel cell system 200 according to Modification 1 of the embodiment of the present invention will be described. First, the device configuration of the fuel cell system 200 will be described with reference to FIG. FIG. 4 is a view schematically showing an example of the configuration of a fuel cell system 200 according to Modification 1 of the embodiment of the present invention.

  As shown in FIG. 4, the fuel cell system 200 according to the first modification of the embodiment further includes the second air supply device 6 in comparison with the fuel cell system 100 according to the embodiment. The configuration is different, and the other configuration is the same. Therefore, in the fuel cell system 200 according to the first modification of the embodiment, the same members as those of the fuel cell system 100 according to the embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

  The second air supplier 6 is a blower that supplies air to the anode off gas discharge path 2. The second air supplier 6 supplies the required amount of air to the anode off gas discharge path 2 in accordance with the flow rate of the anode off gas discharged from the anode off gas discharge path 2. In the fuel cell system 100 according to the embodiment of the present invention, the anode off gas and the air merge at the downstream side of the purge valve 3 in the anode off gas discharge path 2 in the flow direction of the anode off gas, and the anode off gas is diluted. Are configured to

  The second air supplier 6 may be a suction type blower that draws air for diluting the anode off gas into the anode off gas discharge path 2 or is a spray type fan that sends air to the anode off gas discharge path 2. May be Further, the second air supply device 6 has a variable air volume supplied to the anode off gas discharge path 2 in accordance with a control instruction from the controller 5. The adjustment of the air volume may be performed, for example, by controlling the number of rotations of the motor that operates the impeller of the second air supply device 6. The second air supplier 6 may be a fan or another fan such as a compressor.

[Air supply control]
Next, FIG. 5 shows the air supply control for supplying air to the anode off gas discharge path 2, which is performed when the purge valve 3 is opened in the fuel cell system 200 according to the first modification of the embodiment of the present invention. Refer to the description. FIG. 5 is a flow chart showing an example of an operation flow of air supply control implemented in a fuel cell system 200 according to the first modification of the embodiment of the present invention.

  Steps S21 to S23 and steps S28 to S33 in FIG. 5 are the same as steps S11 to S19 in FIG.

  In step S22 or step S23, when the flow rate of air supplied to the anode off gas discharge path 2 at the time of power generation or other than power generation is set, the controller 5 combines the used air supply units based on the set flow rate of air. It is determined whether to use only the first air supplier 4, only the second air supplier 6, or the first air supplier 4 and the second air supplier 6 (step S24).

  The selection method of the combination of the air supply to be used holds beforehand the information regarding the performance which the 1st air supply 4 and the 2nd air supply 6 have, and it is based on this information and the set flow rate of air. It may be configured to select a combination of air supply devices. Alternatively, whether to select only the first air supplier 4 or only the second air supplier 6 according to the set flow rate of air, the first air supplier 4 and the second air supplier It may be decided whether to select both of the six.

  When the first air supplier 4 is selected as a result of the determination in step S24, the controller 5 sets the flow rate of the air supplied to the anode off gas discharge path 2 by the first air supplier 4 (step S25). When the second air supplier 6 is selected, the controller 5 sets the flow rate of the air supplied to the anode off gas discharge path 2 by the second air supplier 6 (step S26). On the other hand, when the first air supplier 4 and the second air supplier 6 are selected, the controller 5 controls the air supplied from the first air supplier 4 and the second air supplier 6 to the anode off gas discharge path 2. The flow rate is set (step S27).

  As described above, the flow rate of air supplied to the anode off gas discharge path 2 is set by the selected combination of air supply devices. Then, in the same manner as step S14 to step S19 shown in FIG. 3, subsequent step S28 to step S33 are performed.

  In addition, although the fuel cell system 200 which concerns on the modification 1 of embodiment was the structure provided with the 1st air supply device 4 and the 2nd air supply device 6, the air supply device provided is limited to these two. Instead, it may be configured to further include another air supply device.

(Modification 2)
[Device configuration]
Next, a fuel cell system 300 according to Modification 2 of the embodiment of the present invention will be described. First, the device configuration of the fuel cell system 300 will be described with reference to FIG. FIG. 6 is a view schematically showing an example of the configuration of a fuel cell system 300 according to Modification 2 of the embodiment of the present invention.

  As shown in FIG. 6, the fuel cell system 300 according to the second modification of the embodiment is further generated in the second air supplier 6 and the fuel cell 1 in comparison with the fuel cell system 100 according to the embodiment. A heat exchanger 7 for heat exchange between a heat medium for recovering heat and air, a heat medium circulation path 8 for the heat medium to circulate between the fuel cell 1 and the heat exchanger 7, a heat medium circulation path 8 And a first temperature detector 9 for detecting a first temperature indicating the temperature of the heat medium. Further, in addition to the function of supplying air to the anode off gas discharge path 2, the first air supply device 4 also has a function of guiding the air to the heat exchanger 7 and cooling the heat medium to control the temperature. But it is different. That is, the first air supplier 4 is configured to supply air to the heat exchanger 7 and to supply the air supplied to the heat exchanger 7 to the anode off gas discharge path 2.

  The fuel cell system 300 according to the second modification of the embodiment is similar to the fuel cell system 100 according to the embodiment in the other configurations. Therefore, in the fuel cell system 300 according to the second modification of the embodiment, the same members as those of the fuel cell system 100 according to the embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

  The heat medium circulation path 8 is a flow path through which a heat medium for maintaining the temperature of the fuel cell 1 at a predetermined target temperature flows, penetrates the fuel cell 1 and the heat exchanger 7, and exchanges heat with the fuel cell 1. It circulates with the vessel 7. In addition, as a heat medium, a cooling water is mentioned, for example. In addition to the above-described fuel cell 1, heat exchanger 7, and first temperature detector 9, the heat medium circulation path 8 is further provided with a flow meter and a pump for circulating a heat medium as required. It is also good.

  The heat exchanger 7 is a device that exchanges heat between the heat medium flowing through the fuel cell 1 and the air. For example, as the heat exchanger 7, a fin and tube type radiator may be mentioned. By heat exchange between the air and the heat medium in the heat exchanger 7, the heat held by the heat medium is released into the air, and the heat medium is cooled. The heat exchanger 7 is configured to be supplied with air by the first air supply device, and this configuration can improve the efficiency of heat exchange between the air and the heat medium.

  The first temperature detector 9 is a device that detects a first temperature indicating the temperature of the heat medium flowing through the heat medium circulation path 8. The first temperature detector 9 may have any configuration as long as it can detect the first temperature indicating the temperature of the heat medium flowing through the heat medium circulation path 8. Further, the position at which the first temperature detector 9 is provided in the heat medium circulation path 8 is arbitrary. For example, as shown in FIG. 6, the first temperature detector 9 is downstream of the heat exchanger 7 in the flow direction of the heat medium, and the heat medium is cooled by heat exchange with air in the heat exchanger 7. It may be provided after the Alternatively, the first temperature detector 9 may be provided downstream of the fuel cell 1 in the flow direction of the heat medium and after the heat medium is heated by the fuel cell 1.

[Air supply control]
Next, FIG. 7 shows air supply control for supplying air to the anode off gas discharge path 2, which is performed when the purge valve 3 is opened in the fuel cell system 300 according to the second modification of the embodiment of the present invention. Refer to the description. FIG. 7 is a flow chart showing an example of the operation flow of air supply control implemented in a fuel cell system 300 according to the second modification of the embodiment of the present invention.

  In addition, since step S41 and step S44-step S53 in FIG. 7 are the same as step S21 and step S24-step S33 in FIG. 5, detailed description is abbreviate | omitted.

  As shown in FIG. 7, in the fuel cell system 300 according to the second modification of the embodiment, the controller 5 determines whether the operation state of the fuel cell 1 is during power generation (during steady operation) or other than during power generation (for example, at startup) It is determined (step S41). The controller 5 acquires the first temperature detected by the first temperature detector 9 when it is determined that the operation state of the fuel cell 1 is at the time of power generation ("YES" in step S41), and the first temperature The flow rate of the anode off gas discharged through the anode off gas discharge path 2 is determined based on Then, the controller 5 sets the flow rate of air supplied to the anode off gas discharge path 2 at the time of power generation according to the obtained flow rate of the anode off gas (step S42).

  On the other hand, when the controller 5 determines that the operating state of the fuel cell 1 is other than during power generation (for example, at start-up) (“NO” in step S41), the first temperature detector 9 detects The temperature is acquired, and the flow rate of the anode off gas discharged through the anode off gas discharge path 2 is determined based on the first temperature. Then, the controller 5 sets the flow rate of air supplied to the anode off gas discharge path 2 at times other than during power generation (for example, at start up) according to the obtained flow rate of the anode off gas (step S43).

  From the flow rate of air set in step S42 or step S43, the controller 5 determines a combination of air supply units to be used (step S44). Then, in the same manner as step S25 to step S33 in FIG. 5, the subsequent step S45 to step S53 are performed.

  In the above-described embodiment and the first modification of the embodiment, the flow rate of air supplied to the anode off gas discharge path 2 is set in advance according to the operation state of power generation or other than power generation (for example, start). On the other hand, in the fuel cell system 300 according to the second modification of the embodiment, the temperature of the anode off gas is estimated from the temperature of the heat medium flowing through the heat medium circulation passage 8 which is the first temperature, and the temperature of the anode off gas On the basis of the above, the flow rate of air required to be supplied to the anode off gas discharge path 2 is determined. In the fuel cell system 300 according to the second modification of the embodiment, the pressure of the anode off gas flowing on the upstream side of the purge valve 3 in the anode off gas discharge path 2 is a preset value.

  With this configuration, the fuel cell system 300 can accurately determine the flow rate of air that is required to be supplied to the anode off gas discharge path 2. That is, regardless of whether the fuel cell 1 generates electricity or the fuel cell 1 generates electricity (for example, at start-up), as shown in FIG. Correspondingly, an appropriate flow rate of air can be supplied to the anode off gas discharge path 2. Therefore, the fuel cell system 300 according to the second modification of the embodiment can supply air with an appropriate flow rate to the anode off gas discharge path 2 even when the temperature of the anode off gas is not constant.

  In addition, a fuel cell system 300 according to the second modification of the embodiment includes the first air supplier 4 and the second air supplier 6, and the first air supplier 4 supplies air to the anode off gas discharge path 2. It was configured to have both the function and the function of supplying air to the heat exchanger 7 to control the temperature of the heat medium. Therefore, when it is possible to supply air of a necessary flow rate to the anode off gas exhaust passage 2 only by the second air supply device 6, the first air supply device 4 does not affect the temperature control of the heat medium. A flow of air can be supplied to the anode off gas discharge path 2, and a shortage of air flow can be compensated by the second air supplier 6.

(Modification 3)
[Device configuration]
Next, a fuel cell system 400 according to Modification 3 of the embodiment of the present invention will be described. First, the device configuration of the fuel cell system 400 will be described with reference to FIG. FIG. 8 is a view schematically showing an example of the configuration of a fuel cell system 400 according to Modification 3 of the embodiment of the present invention.

  As shown in FIG. 8, the fuel cell system 400 according to the third modification of the embodiment is further provided upstream of the purge valve 3 in the flow direction of the anode off gas as compared with the fuel cell system 100 according to the embodiment. The difference is that the pressure detector 10 is provided, and the other configuration is similar to that of the fuel cell system 100 according to the embodiment. Therefore, in the fuel cell system 400 according to the third modification of the embodiment, the same members as those of the fuel cell system 100 according to the embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  The pressure detector 10 is a device that detects the pressure of the anode off gas flowing on the upstream side of the purge valve 3 in the anode off gas discharge path 2. Here, the pressure of the anode off gas flowing on the upstream side of the purge valve 3 in the anode off gas discharge path 2 can be regarded as the supply pressure of the fuel gas. Therefore, the pressure detector 10 may have any configuration as long as it can detect the supply pressure of fuel gas. For example, as the pressure detector 10, a differential pressure gauge capable of measuring a differential pressure with the atmospheric pressure may be mentioned.

[Air supply control]
Next, FIG. 9 shows air supply control for supplying air to the anode off gas discharge path 2, which is performed when the purge valve 3 is opened in the fuel cell system 400 according to the third modification of the embodiment of the present invention. Refer to the description. FIG. 9 is a flow chart showing an example of the operation flow of air supply control implemented in a fuel cell system 400 according to the third modification of the embodiment of the present invention.

  Step S61 and step S64 to step S69 in FIG. 9 are the same as step S11 and step S14 to step S19 shown in FIG. 3 and thus detailed description will be omitted.

  As shown in FIG. 9, in the fuel cell system 400 according to the third modification of the embodiment, the controller 5 is operating when the fuel cell 1 is in power generation (during steady operation) or other than power generation (for example, at startup) It is determined (step S61). When the controller 5 determines that the operation state of the fuel cell 1 is at the time of power generation ("YES" in step S61), the upstream side of the purge valve 3 of the anode off gas discharge path 2 detected by the pressure detector 10. The information indicating the pressure of the anode off gas flowing through is obtained, and the flow rate of the anode off gas flowing through the anode off gas discharge path 2 is determined based on the pressure difference between the pressure and the atmospheric pressure. Then, the controller 5 sets the flow rate of air supplied to the anode off gas discharge path 2 at the time of power generation according to the obtained flow rate of the anode off gas (step S62).

  On the other hand, when controller 5 determines that the operating state of fuel cell 1 is other than during power generation (for example, at start-up) ("NO" in step S61), the anode off-gas discharge path detected by pressure detector 10. Information indicating the pressure of the anode off gas flowing on the upstream side of the purge valve 3 of 2 is acquired, and the flow rate of the anode off gas discharged through the anode off gas discharge path 2 based on the pressure difference between the pressure and the atmospheric pressure. Ask for Then, the controller 5 sets the flow rate of air to be supplied to the anode off gas discharge path 2 at times other than during power generation (for example, at start up) according to the obtained flow rate of the anode off gas (step S63).

  Then, in the same manner as step S14 to step S19 in FIG. 3, the subsequent step S64 to step S69 are performed.

  In the fuel cell system 300 according to the second modification of the embodiment described above, it is assumed that the pressure of the anode off gas flowing on the upstream side of the purge valve 3 of the anode off gas discharge path 2 becomes a preset value. . However, the pressure difference between the pressure of the anode off gas flowing through the upstream side of the purge valve 3 of the anode off gas discharge path 2 and the atmospheric pressure may change. Further, as shown in FIG. 1, when the pressure difference changes, the flow rate of the anode off gas flowing through the anode off gas discharge path 2 changes.

  Therefore, in the air supply control performed by the fuel cell system 400 according to the third modification of the embodiment, the pressure detector 10 detects the pressure of the anode off gas flowing on the upstream side of the purge valve 3 in the anode off gas discharge path 2. Then, based on the pressure difference between the detected pressure and the atmospheric pressure, the flow rate of the anode off gas flowing through the anode off gas discharge path 2 is determined. Therefore, in the fuel cell system 400 according to the third modification of the embodiment, the pressure difference between the pressure of the anode off gas flowing through the upstream side of the purge valve 3 of the anode off gas discharge path 2 and the atmospheric pressure changes. Also, the required flow rate of air can be supplied to the anode off gas discharge path 2.

  The fuel cell system 400 according to the third modification of the embodiment is configured to include only the first air supply device 4 in the same manner as the fuel cell system 100 according to the embodiment. However, it is not limited to this configuration. For example, the fuel cell system 400 according to the third modification of the embodiment may be configured to further include the second air supply device 6 similarly to the fuel cell system 200 according to the first modification of the embodiment. Further, the fuel cell system 400 according to the third modification of the embodiment includes the heat exchanger 7 and the heat medium circulation path 8 similarly to the fuel cell system 300 according to the second modification of the embodiment, and supplies the first air. In addition to the function of supplying air to the anode off gas discharge path 2, the unit 4 may also be configured to supply air to the heat exchanger 7 to cool the heat medium to control the temperature.

(Modification 4)
[Device configuration]
Next, a fuel cell system 500 according to Modification 4 of the embodiment of the present invention will be described. First, the device configuration of the fuel cell system 500 will be described with reference to FIG. FIG. 10 is a diagram schematically showing an example of the configuration of a fuel cell system 500 according to Modification 4 of the embodiment of the present invention.

  As shown in FIG. 10, the fuel cell system 500 according to the fourth modification of the embodiment further includes a second temperature detector 11 in the anode off gas discharge path 2 as compared to the fuel cell system 100 according to the embodiment. The difference is that the temperature of the anode off gas flowing through the anode off gas discharge path 2 is detected, and the other configuration is the same as that of the fuel cell system 100 according to the embodiment. Therefore, in the fuel cell system 500 according to the fourth modification of the embodiment, the same members as those of the fuel cell system 100 according to the embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

  The second temperature detector 11 is a device that detects the temperature of the anode off gas flowing through the anode off gas discharge path 2. The second temperature detector 11 may be any detector that can detect the temperature of the anode off gas flowing through the anode off gas discharge path 2. In the example shown in FIG. 10, the second temperature detector 11 is provided at a position upstream of the purge valve 3 in the anode off gas discharge path 2 in the flow direction of the anode off gas, but the provided position is the same. The position of the anode off gas flowing through the anode off gas discharge path 2 may be any position that can be detected.

[Air supply control]
Next, FIG. 11 shows air supply control for supplying air to the anode off gas discharge path 2 which is performed when the purge valve 3 is opened in the fuel cell system 500 according to the fourth modification of the embodiment of the present invention. Refer to the description. FIG. 11 is a flow chart showing an example of the operation flow of air supply control performed in a fuel cell system 500 according to the fourth modification of the embodiment of the present invention.

  Step S71 and step S74 to step S79 in FIG. 11 are the same as step S11 and step S14 to step S19 shown in FIG. 3, and therefore detailed description will be omitted.

  As shown in FIG. 11, in the fuel cell system 400 according to the fourth modification of the embodiment, the controller 5 is operating when the fuel cell 1 is in power generation (during steady operation) or other than power generation (for example, at startup) It is determined (step S71). When controller 5 determines that the operation state of fuel cell 1 is at the time of power generation ("YES" in step S71), anode off gas flowing through anode off gas discharge path 2 detected by second temperature detector 11 Information indicating the temperature of the fuel cell is obtained, and the flow rate of the anode off gas discharged through the anode off gas discharge path 2 is determined based on the temperature. Then, the controller 5 sets the flow rate of air supplied to the anode off gas discharge path 2 at the time of power generation according to the obtained flow rate of the anode off gas (step S72).

  On the other hand, when the controller 5 determines that the operating state of the fuel cell 1 is other than during power generation (for example, at startup) ("NO" in step S71), the anode off gas detected by the second temperature detector 11 Information indicating the temperature of the anode off gas flowing through the discharge path 2 is acquired, and based on the temperature, the flow rate of the anode off gas flowing through the anode off gas discharge path 2 and discharged is determined. Then, the controller 5 sets the flow rate of air supplied to the anode off gas discharge path 2 at times other than during power generation, in accordance with the obtained flow rate of the anode off gas (step S73).

  Then, in the same manner as step S14 to step S19 in FIG. 3, the subsequent step S74 to step S79 are performed.

  In the above-described embodiment and the first modification of the embodiment, the flow rate of air supplied to the anode off gas discharge path 2 is set in advance according to the operation state of power generation or other than power generation (for example, start). On the other hand, in the fuel cell system 500 according to the fourth modification of the embodiment, it is necessary to measure the temperature of the anode off gas which is the second temperature and supply it to the anode off gas discharge path 2 based on the temperature of the anode off gas. The flow rate of the air to be In the fuel cell system 500 according to the fourth modification of the embodiment, the pressure of the anode off gas flowing on the upstream side of the purge valve 3 of the anode off gas discharge path 2 is a preset value.

  With such a configuration, the fuel cell system 500 can accurately determine the flow rate of air necessary for supplying the anode off gas discharge path 2. That is, regardless of whether the fuel cell 1 generates electricity or the fuel cell 1 generates electricity (for example, at start-up), as shown in FIG. Correspondingly, an appropriate flow rate of air can be supplied to the anode off gas discharge path 2. Therefore, the fuel cell system 500 according to the fourth modification of the embodiment can supply air of an appropriate flow rate to the anode off gas discharge path 2 even when the temperature of the anode off gas is not constant.

  In addition, the fuel cell system 500 which concerns on the modification 4 of embodiment was the structure provided only with the 1st air supply device 4 similarly to the fuel cell system 100 which concerns on embodiment. However, it is not limited to this configuration. For example, the fuel cell system 500 according to the fourth modification of the embodiment may be configured to further include the second air supply device 6 similarly to the fuel cell system 200 according to the first modification of the embodiment. Further, the fuel cell system 500 according to the modification 4 of the embodiment includes the heat exchanger 7 and the heat medium circulation path 8 similarly to the fuel cell system 300 according to the modification 2 of the embodiment, and supplies the first air. In addition to the function of supplying air to the anode off gas discharge path 2, the unit 4 may also be configured to supply air to the heat exchanger 7 to cool the heat medium to control the temperature.

  From the above description, many modifications and other embodiments of the present invention will be apparent to those skilled in the art. For example, in the case where the fuel cell system has a configuration in which the temperature of the anode off gas flowing through the anode off gas discharge path 2 and the pressure of the anode off gas flowing upstream of the purge valve 3 in the anode off gas discharge path 2 respectively change The fuel cell system 300 according to the second embodiment may be combined with the fuel cell system 400 according to the third modification, or the fuel cell system 400 according to the third modification may be combined with the fuel cell system 500 according to the fourth modification. That is, the controller 5 may be configured to set the flow rate of air supplied to the anode off gas discharge path 2 based on the temperature and pressure of the anode off gas, at the time of power generation or other than power generation.

  Accordingly, the above description should be taken as exemplary only, and is provided for the purpose of teaching those skilled in the art the best mode of carrying out the present invention. The structural and / or functional details may be substantially altered without departing from the spirit of the present invention.

  The present invention can be widely applied to a fuel cell system that performs anode purge.

DESCRIPTION OF SYMBOLS 1 fuel cell 2 anode off gas discharge path 3 purge valve 4 1st air supply device 5 controller 6 2nd air supply device 7 heat exchanger 8 heat medium circulation path 9 1st temperature sensor 10 pressure sensor 11 2nd temperature detection 100 Fuel cell system 200 Fuel cell system 300 Fuel cell system 400 Fuel cell system 500 Fuel cell system

Claims (13)

A fuel cell generating electricity by an electrochemical reaction between a fuel gas supplied to the anode and an oxidant gas supplied to the cathode;
An anode off gas discharge path for discharging an anode off gas discharged from an anode of the fuel cell;
A purge valve provided in the anode off gas discharge path;
A first air supplier for supplying air for diluting the anode off gas to the anode off gas discharge path;
And a controller,
When the controller opens the purge valve other than during power generation of the fuel cell, the controller discharges more air from the anode off gas than when opening the purge valve during power generation of the fuel cell. A fuel cell system for controlling a first air supply to supply a path. A heat medium circulation path through which a heat medium for recovering heat generated by the fuel cell is circulated;
A heat exchanger provided in the heat medium circulation path,
The fuel cell system according to claim 1, wherein the first air supplier supplies the air to the heat exchanger, and supplies the air supplied to the heat exchanger to the anode off gas discharge path.   The controller calculates the flow rate of the air supplied to the anode off gas discharge path based on a first temperature indicating the temperature of the heat medium circulating the heat medium circulation path, and the flow rate of the air is calculated according to the calculated flow rate. The fuel cell system according to claim 2, wherein the first air supplier is controlled to operate.   The controller calculates the flow rate of the air supplied to the anode off gas discharge path based on the pressure of the anode off gas flowing on the upstream side of the purge valve in the anode off gas discharge path, and calculates the flow rate of the air The fuel cell system according to claim 2, wherein the first air supply device is controlled to operate in response to the control signal.   The controller determines a flow rate of the air supplied to the anode off gas discharge path based on a second temperature that is a temperature of the anode off gas flowing through the anode off gas discharge path, and determines the determined flow rate of the air. The fuel cell system according to claim 2, wherein in response, the first air supplier is controlled to operate. The air conditioner further comprises a second air supplier for supplying the air to the anode off gas discharge path.
When the controller opens the purge valve at least during power generation of the fuel cell, the controller generates more air as the anode off-gas when the fuel cell generates power than when the purge valve is opened. The fuel cell system according to claim 1, wherein at least one of the first air supplier and the second air supplier is controlled to operate so as to be supplied to the discharge path. A heat medium circulation path through which a heat medium for recovering heat generated by the fuel cell is circulated;
A heat exchanger provided in the heat medium circulation path,
The fuel cell system according to claim 6, wherein the first air supplier supplies the air to the heat exchanger and supplies the air supplied to the heat exchanger to the anode off gas discharge path.   The controller calculates the flow rate of the air supplied to the anode off gas discharge path based on a first temperature indicating the temperature of the heat medium circulating the heat medium circulation path, and the flow rate of the air is calculated according to the calculated flow rate. The fuel cell system according to claim 7, wherein at least one of the first air supplier and the second air supplier is controlled to operate.   The controller calculates the flow rate of the air supplied to the anode off gas discharge path based on the pressure of the anode off gas flowing on the upstream side of the purge valve in the anode off gas discharge path, and calculates the flow rate of the air The fuel cell system according to claim 7, wherein at least one of the first air supply device and the second air supply device is controlled to operate according to The controller determines a flow rate of the air supplied to the anode off gas discharge path based on a second temperature that is a temperature of the anode off gas flowing through the anode off gas discharge path, and determines the determined flow rate of the air. The fuel cell system according to claim 7, wherein at least one of the first air supplier and the second air supplier is controlled to operate accordingly.   The fuel cell system according to claim 3, further comprising a first temperature sensor provided in the heat medium circulation path for detecting the first temperature.   The fuel cell system according to claim 4 or 9, further comprising a pressure sensor that detects the pressure of the anode off gas flowing upstream of the purge valve in the anode off gas discharge path. The fuel cell system according to claim 5, further comprising a second temperature sensor that detects the second temperature.

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