JP2018160430A - Fuel cell system and operational method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To determine whether or not a supplying trouble in supply of an oxygen gas for power generation to a fuel cell unit has been caused, without bringing about a structural complication, such as additionally involving a device.SOLUTION: A fuel cell system comprises: a fuel cell unit 12 having an anode and a cathode; a blower 13 for power generation oxygen for supplying the cathode with an oxygen gas for power generation; an operation control part 3; a voltage detector part 18 for detecting an output voltage of the fuel cell unit 12; and a power detector part 19 for detecting an output power of the fuel cell unit 12. The operation control part 3 adjusts an output of the blower 13 for power generation oxygen so as to make a target flow rate adequate for an output power of the fuel cell unit 12. When the output voltage shows fluctuation in a predetermined permissible range or exceeding the range during a time when the output power is fixed, it is determined that a trouble in supplying oxygen gas for power generation to the cathode occurs.SELECTED DRAWING: Figure 1

Description

  The present invention includes a reforming unit that reforms raw fuel to generate fuel gas, an anode to which the fuel gas generated in the reforming unit is supplied, and a cathode to which power generation oxygen gas is supplied. A fuel cell unit, a combustion unit for burning a fuel component in exhaust fuel gas discharged from the anode after being used in a power generation reaction in the fuel cell unit, and supplying the power generation oxygen gas to the cathode The present invention relates to a fuel cell system including a power generation oxygen blower and an operation control unit. The present invention also relates to a method for operating a fuel cell system.

  In the fuel cell system, power generation oxygen gas is supplied from a power generation oxygen blower to a cathode of a fuel cell section through a gas supply path, and the gas supply path is opened in the middle of the gas supply path. An on-off valve that can be switched between a closed state and a closed state is provided (see, for example, Patent Document 1).

  There is no problem when the blower and the open / close valve are operating normally, but if the blower or the open / close valve becomes abnormal as the fuel cell is used, the oxygen gas for power generation is well supplied to the cathode of the fuel cell unit. There is a risk of being lost. In order to detect the occurrence of such an abnormality, the following configuration has been proposed.

  That is, a separate on-off valve is provided on the lower side of the air flow direction than the on-off valve to be diagnosed in the gas supply path, and the internal pressure is measured on the upper and lower sides of the on-off valve in the air flow direction of the diagnosis target. A pressure sensor that determines whether the on / off valve is operating abnormally based on fluctuations in internal pressure associated with the start of fuel cell operation, fluctuations in internal pressure before and after opening / closing another on / off valve, etc. Patent Document 2).

Japanese Patent Application Laid-Open No. 2015-185249 JP 2004-95425 A

  The above conventional configuration requires a plurality of separately attached devices such as another on-off valve and a plurality of pressure sensors, which is disadvantageous in that the number of parts increases and the cost increases. Moreover, in the above conventional configuration, it is possible to determine the abnormal operation of the on-off valve, but there is a disadvantage that it is not possible to determine the abnormal operation of the blower for power generation oxygen.

  When the blower operation abnormality is described, it is easy to determine that the blower is malfunctioning when the blower fails and no air blowing operation is performed. On the other hand, for example, when an abnormality that water enters the blower has occurred, the operation of the blower can be continued, and if the output of the fuel cell is low, It is possible to continue operation substantially the same as normal operation. However, if the operation is continued in such a state that water has entered the blower, the blower may be significantly damaged in a short period of time.

The invasion of water into the blower will be described.
Conventionally, there is a fuel cell in which water is supplied into the fuel cell to wet the anode and cathode, and in this configuration, a large amount of water is present inside the fuel cell when operation is stopped. Will do.

  During the shutdown, the raw fuel gas is supplied via the reformer to prevent the cathode from being oxidized by the oxidant gas remaining inside the fuel cell. There is a case where the pressure holding process is set to a higher value.

  In addition, when power generation is started from an operation stop state, combustion air may be supplied via a reformer in order to discharge unburned gas remaining in the combustion section. At this time, the pressure inside the fuel cell may change to a higher level.

  As a result, when the on-off valve provided in the gas supply path through which the oxygen gas for power generation flows is broken, the pressure inside the fuel cell changes to a high level when the operation is stopped or started. Thus, part of the water present inside the fuel cell may enter the blower through the gas supply path.

  The present invention has been made in view of the above-mentioned problems, and the object thereof is to prevent the problem of supplying oxygen gas for power generation to the fuel cell unit without complicating the structure such as providing a separate device. The point is to be able to determine that it has occurred.

The characteristic configuration of the fuel cell system according to the present invention is:
A reforming section for reforming raw fuel to generate fuel gas;
A fuel cell unit having an anode to which the fuel gas generated in the reforming unit is supplied, and a cathode to which power generation oxygen gas is supplied;
A combustion section for burning a fuel component in exhaust fuel gas discharged from the anode after being used in a power generation reaction in the fuel cell section;
A power generation oxygen blower for supplying the power generation oxygen gas to the cathode;
An operation control unit,
A voltage detection unit for detecting an output voltage of the fuel cell unit;
A power detection unit for detecting output power of the fuel cell unit,
The operation controller is
Adjusting the output of the power generation oxygen blower so that the flow rate per unit time of the power generation oxygen gas becomes a target flow rate commensurate with the output power of the fuel cell unit,
Supply of the oxygen gas for power generation to the cathode when the output voltage detected by the voltage detector shows a fluctuation exceeding a predetermined allowable range while the output power detected by the power detector is constant The point is that it is determined that a problem has occurred.

  The operation control unit adjusts the output of the power generation oxygen blower so that the target flow rate is commensurate with the output power of the fuel cell unit. For example, an abnormality has occurred in the operation of the blower due to water intrusion, etc. In some cases, a turbulence peculiar to the flow rate of the air sent out from the blower occurs, and the output voltage of the fuel cell unit may fluctuate greatly in accordance with this turbulence.

  Therefore, using this fact, if the output voltage of the fuel cell unit fluctuates beyond the allowable range under the condition that the output power of the fuel cell unit is constant, a problem occurs in the supply of oxygen gas for power generation to the cathode. Can be determined. In addition, in order to detect the driving | running state of a fuel cell, a voltage detection part and an electric power detection part are the structures which are originally required.

  As a result, by using a device that is originally required, it is possible to determine that a failure in supplying oxygen gas for power generation to the fuel cell unit has occurred without complicating the structure such as providing a separate device. It became a thing.

  Another characteristic configuration of the fuel cell system according to the present invention is that when the operation control unit determines that there is a problem in the supply of the oxygen gas for power generation to the cathode, the output power of the fuel cell unit Is that a low output operation is performed for a predetermined period.

  For example, even if there is an abnormality in the operation of the power generation oxygen blower due to water intrusion, etc., when the fuel cell unit is operating in a low output state, it is substantially the same as normal operation. It is possible to continue stable operation with little fluctuation in output voltage. Therefore, when it is determined that a malfunction has occurred, a low output operation is performed, so that disadvantages such as an early breakage due to excessive force applied to the power generation oxygen blower can be avoided. As a result of determining that a problem has occurred, it is possible to take some measures while the predetermined time has elapsed. Therefore, the low output operation is performed for a predetermined period, and it continues unnecessarily for a long time. You can avoid that.

Still another characteristic configuration of the fuel cell system according to the present invention is:
The operation controller is
It is determined that there is a problem in the supply of the oxygen gas for power generation to the cathode, and the current output of the oxygen blower for power generation indicates the flow rate per unit time of the oxygen gas for power generation as the fuel cell. When the target flow rate corresponding to the output power of the unit is larger than the set value from the reference output, there is a problem in the supply of the oxygen gas for power generation due to an increase in the flow resistance of the oxygen gas for power generation Determine that it has occurred,
When it is determined that there is a problem in the supply of the oxygen gas for power generation to the cathode and the current output of the oxygen generator blower is not greater than the set value from the reference output, the power generation The point is that it is determined that a failure in the supply of the oxygen gas for power generation due to the oxygen blower has occurred.

  Even if there is a problem with the supply of oxygen gas for power generation, the cause of the problem is not only the cause of the oxygen blower for power generation, but also any gas supply path through which oxygen gas for power generation flows. It is also conceivable that the channel resistance is increased due to a factor.

  If the cause is an increase in flow path resistance, even if the output of the power generation oxygen blower is adjusted to the reference output corresponding to the target flow rate, the power generation oxygen gas at the target flow rate cannot be supplied. As a result, when the operation control unit adjusts the output of the power generation oxygen blower so as to achieve the target flow rate, the output of the power generation oxygen blower becomes an output that is larger than the reference output by a set amount or more. On the other hand, if the generated oxygen blower is the cause, the output of the generated oxygen blower is less likely to vary greatly from the reference output.

  Therefore, in the above-described characteristic configuration, when it is determined that there is a problem in the supply of the oxygen gas for power generation, it is caused by an increase in the flow resistance or the blower for oxygen for power generation. It is possible to determine whether or not.

Still another characteristic configuration of the fuel cell system according to the present invention is:
The operation controller is
When it is determined that there is a problem in the supply of the oxygen gas for power generation to the cathode and the current output of the oxygen generator blower is not greater than the set value from the reference output, the power generation The point is that it is determined that there is a problem in the supply of the oxygen gas for power generation due to water intrusion into the oxygen blower.

  According to the above characteristic configuration, if the output voltage of the fuel cell unit fluctuates and a problem has occurred, but the output of the blower for generated oxygen is not larger than the set value from the reference output, Determined to be caused by water intrusion into the blower. That is, in such a case, there is no problem in the blowing capacity itself of the power generation oxygen blower, and it can be assumed that water is intruded.

  Therefore, it can be determined whether or not the intrusion of water is caused by the difference in the output level of the power generation oxygen blower.

The feature of the operation method of the fuel cell system according to the present invention is:
A fuel cell unit having a reforming unit that reforms raw fuel to generate fuel gas, an anode to which the fuel gas generated in the reforming unit is supplied, and a cathode to which oxygen gas for power generation is supplied A combustion section for burning a fuel component in the exhaust gas discharged from the anode after being used in a power generation reaction in the fuel cell section, and a power generation oxygen for supplying the power generation oxygen gas to the cathode A fuel cell system comprising a blower for a vehicle,
The fuel cell system includes a voltage detection unit that detects an output voltage of the fuel cell unit, and a power detection unit that detects output power of the fuel cell unit,
The output of the power generation oxygen blower is adjusted so that the flow rate per unit time of the power generation oxygen gas becomes a target flow rate corresponding to the output power of the fuel cell unit,
While the output power detected by the power detection unit is constant, a voltage detection step of detecting an output voltage by the voltage detection unit;
A failure determination step of determining that a failure has occurred in the supply of the oxygen gas for power generation to the cathode when the output voltage detected in the voltage detection step shows a fluctuation exceeding a predetermined allowable range. In the point.

  The output of the blower for oxygen generation is adjusted so that the target flow rate is commensurate with the output power of the fuel cell unit.For example, if an abnormality occurs in the blower operation due to water intrusion, etc., the blower Disturbances peculiar to the flow rate of the air sent out may occur, and the output voltage of the fuel cell unit may fluctuate greatly up and down with this disturbance.

  Therefore, in the voltage detection step, when the output power of the fuel cell unit is constant, the output voltage of the fuel cell unit is detected, and in the failure determination step, if the output voltage shows a fluctuation exceeding a predetermined allowable range. It can be determined that there is a problem in the supply of oxygen gas for power generation to the cathode. In addition, in order to detect the driving | running state of a fuel cell, a voltage detection part and an electric power detection part are the structures which are originally required.

  As a result, by using a device that was originally required, there was a problem in supplying oxygen gas for power generation to the fuel cell unit without complicating the structure of the fuel cell system, such as providing a separate device. It became possible to distinguish this.

Another feature of the operation method of the fuel cell system according to the present invention is:
When it is determined in the failure determination step that a failure has occurred in the supply of the oxygen gas for power generation to the cathode, a low output operation for setting the output power of the fuel cell unit to a predetermined low output state is performed for a predetermined period. It has a countermeasure process to be performed.

  For example, even if there is an abnormality in the operation of the power generation oxygen blower due to water intrusion, etc., when the fuel cell unit is operating in a low output state, it is substantially the same as normal operation. It is possible to continue stable operation with little fluctuation in output voltage. Therefore, when it is determined that a malfunction has occurred, a low output operation is performed, so that disadvantages such as an early breakage due to excessive force applied to the power generation oxygen blower can be avoided. As a result of determining that a problem has occurred, it is possible to take some measures while the predetermined time has elapsed. Therefore, the low output operation is performed for a predetermined period, and it continues unnecessarily for a long time. You can avoid that.

Still another feature of the operating method of the fuel cell system according to the present invention is:
In the failure determination step, when it is determined that a failure has occurred in the supply of the oxygen gas for power generation to the cathode,
If the current output of the power generation oxygen blower is larger than a set value from a reference output when the flow rate per unit time of the power generation oxygen gas is set to a target flow rate corresponding to the output power of the fuel cell unit , Presuming that there is a problem in the supply of oxygen gas for power generation due to an increase in flow resistance of the oxygen gas for power generation,
If the current output of the power generation oxygen blower is not greater than or equal to the set value from the reference output, it is estimated that the power generation oxygen gas supply failure caused by the power generation oxygen blower has occurred. A defect cause estimation step.

  Even if there is a problem with the supply of oxygen gas for power generation, the cause of the problem is not only the cause of the oxygen blower for power generation, but also any gas supply path through which oxygen gas for power generation flows. It is also conceivable that the channel resistance is increased due to a factor.

  If the cause is an increase in flow path resistance, even if the output of the power generation oxygen blower is adjusted to the reference output corresponding to the target flow rate, the power generation oxygen gas at the target flow rate cannot be supplied. As a result, when the operation control unit adjusts the output of the power generation oxygen blower so as to achieve the target flow rate, the output of the power generation oxygen blower becomes an output that is larger than the reference output by a set amount or more. On the other hand, if the generated oxygen blower is the cause, the output of the generated oxygen blower is less likely to vary greatly from the reference output.

  Therefore, in the above feature, when it is determined that there is a problem in the supply of the oxygen gas for power generation, it is caused by an increase in the flow resistance or the blower for power generation oxygen. It is possible to determine whether it exists.

Still another feature of the operating method of the fuel cell system according to the present invention is:
When it is estimated in the failure cause estimation step that a failure in the supply of oxygen gas for power generation due to the blower for oxygen for power generation has occurred, the output power of the fuel cell unit is set to a predetermined low output state There exists a countermeasure process which performs a low output driving | running for a predetermined period.

  According to the above method, when it is estimated that there is a problem with the supply of oxygen gas for power generation due to the oxygen blower for power generation, the output power of the fuel cell unit is set to a predetermined low output state. When it is assumed that this is the cause of this, another measure will be taken.

  Therefore, appropriate measures can be taken only when the power generation oxygen blower is the cause.

Still another feature of the operating method of the fuel cell system according to the present invention is:
In the failure cause estimation step, when it is estimated that a failure in the supply of oxygen gas for power generation due to the blower for oxygen for power generation has occurred, at a predetermined timing during which the fuel cell unit does not generate power, The power generation oxygen blower is operated to flow the power generation oxygen gas from the power generation oxygen blower toward the cathode.

  According to the above method, a large amount of water is present on the cathode side by flowing power generation oxygen gas from the power generation oxygen blower toward the cathode at an appropriate timing while the fuel cell unit is not generating power. However, water can be prevented from entering the blower for power generation oxygen.

Still another feature of the operating method of the fuel cell system according to the present invention is:
It is preferable that the predetermined timing is a timing at which a pressure from the cathode toward the power generation oxygen blower is applied while the fuel cell unit is not generating power.

  According to the above method, water flows into the power generation oxygen blower by flowing the power generation oxygen gas from the power generation oxygen blower toward the cathode at the timing when the pressure from the cathode toward the power generation oxygen blower is applied. Can be prevented more accurately.

It is a schematic block diagram of a fuel cell system. It is structure explanatory drawing of a cell. It is a flowchart explaining a driving | running method. It is a figure which shows the actual measurement data of a stable driving | running state. It is a figure which shows the actual measurement data of an abnormal driving | running state.

Embodiments according to the present invention will be described below with reference to the drawings.
A fuel cell system and an operation method thereof according to the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram showing a configuration of a fuel cell system. The fuel cell system reforms raw fuel gas (for example, city gas containing methane) as raw fuel to generate fuel gas, and a fuel gas supplied from the fuel gas generating device 1 A fuel cell power generation device 2 that generates power using the fuel, and an operation control unit 3 that controls the operation of the fuel gas generation device 1 and the fuel cell power generation device 2 are provided.

  The fuel gas generator 1 includes a reforming unit 4 that reforms raw fuel gas to generate a fuel gas mainly composed of hydrogen, and a combustion unit 5 that burns fuel components and heats the reforming unit 4. A raw fuel blower 6 for supplying raw fuel gas to the reforming section 4 through the raw fuel supply path L1, and a combustion oxygen blower 7 for supplying combustion oxygen gas to the combustion section 5 through the combustion oxygen supply path L2 A first on-off valve 8 that can open and close the raw fuel supply path L1, and a second on-off valve 9 that can open and close the combustion oxygen supply path L2. The raw fuel supply passage L1 is provided with a raw fuel flow meter 10 for measuring the flow rate of the raw fuel gas supplied by the raw fuel blower 6, and supplied to the combustion oxygen supply passage L2 by the combustion oxygen blower 7. A combustion oxygen flow meter 11 for measuring the flow rate of the combustion oxygen is provided.

  The reforming unit 4 reforms the raw fuel gas in the presence of water vapor to generate a fuel gas mainly composed of hydrogen. Specifically, the reforming unit 4 steam-reforms the raw fuel gas using heat generated in the combustion unit 5 provided adjacent to the reforming unit 4 so that hydrogen is a main component, and as a by-product. A reformed gas containing carbon monoxide and carbon dioxide is generated. Although not shown, the reforming unit 4 also performs a process of removing carbon monoxide contained in the reformed gas after reforming. The fuel gas generated by the reforming unit 4 is supplied to the fuel cell power generator 2 through the fuel gas supply path L3.

  The supply amount of the raw fuel gas supplied through the raw fuel supply path L1 is measured by the raw fuel flow meter 10, and the operation control unit 3 controls the raw fuel so that the measured flow rate becomes a preset target flow rate. The output of the blower 6 is adjusted. In a state where the raw fuel blower 6 is not operating, for example, when the operation is stopped, the first on-off valve 8 is closed.

  The combustion unit 5 generates heat by burning the combustible gas. As the combustible gas, as will be described later, exhaust gas containing hydrogen that has not been consumed in the power generation reaction in the fuel cell power generation device 2, raw fuel gas, or a mixture of both can be used. In addition, combustion air (oxygen) for the combustible gas is supplied to the combustion unit 5 via the combustion oxygen supply path L2.

  The supply amount of the combustion oxygen gas supplied through the combustion oxygen supply path L2 is measured by the combustion oxygen flow meter 11, and the operation control unit 3 is set so that the measured flow rate becomes a preset target flow rate. Adjusts the output of the combustion oxygen blower 7. When the combustion oxygen blower 7 is not operating, for example, when the operation is stopped, the second on-off valve 9 is closed.

  The fuel cell power generation device 2 is supplied with the fuel gas and the oxygen gas for power generation as described above, and supplies the fuel cell unit 12 with the power generation oxygen gas through the power generation oxygen supply path L4. For generating electric power, a third on-off valve 14 capable of opening and closing the electric power generation oxygen supply path L4, a water tank 15 for storing cooling water for cooling the fuel cell unit 12, and an oxygen gas for electric power generation The fourth on-off valve 16 that can freely open and close the power generation oxygen discharge path L5 through which the gas that has not been consumed passes, the pump 17 for circulating and supplying cooling water, and the voltage for detecting the output voltage of the fuel cell unit 12 A detection unit 18 and a power detection unit 19 that detects the output power of the fuel cell unit 12 are provided. The power generation oxygen supply path L4 is provided with a power generation oxygen flow meter 20 for measuring the flow rate of the power generation oxygen gas supplied by the power generation oxygen blower 13.

  The fuel cell unit 12 is a solid polymer fuel cell, and as shown in FIG. 2, one electrolyte membrane 22 made of a solid polymer is sandwiched between an anode (fuel electrode) 23 and a cathode (oxygen electrode) 24. Cell C, and a plurality of cells C are stacked.

  The anode 23 includes a gas diffusion layer 23a and a catalyst layer 23b, and the fuel gas supplied to the fuel gas channel 26a formed on one surface of the first separator 26 on the side facing the gas diffusion layer 23a is gas diffusion layer 23a. And reach the catalyst layer 23b. Similarly, the cathode 24 includes a gas diffusion layer 24a and a catalyst layer 24b, and oxygen (air) supplied to an air flow path 27a formed on one surface of the second separator 27 facing the gas diffusion layer 24a. The catalyst layer 24b is reached through the gas diffusion layer 24a. The catalyst layers 23b and 24b are constituted by a carrier carrying a metal catalyst and promote a chemical reaction.

  A cooling water passage 27b through which cooling water flows is formed between the second separator 27 and the first separator 26 of the adjacent cell C. The cooling water channel 27b and the separators 26 and 27 constitute a cooling unit 28 (see FIG. 1) that cools the fuel cell unit 12. The cooling water circulation path 29 connected to the cooling water flow path 27 b is provided with a water tank 15 and a pump 17. When the pump 17 is operated, the cooling water stored in the water tank 15 is supplied to the fuel cell unit 12. After passing through the cooling water flow path 27b, it is circulated and supplied so as to return to the water tank 15.

In the fuel cell unit 12, the reformed fuel gas is supplied to the anode 23, and oxygen (air) is supplied to the cathode 24 to perform a power generation reaction. The output power (that is, the amount of power generation reaction) of the fuel cell unit 12 is adjusted by the operation control unit 3 using an inverter (not shown), and the power is supplied to a power consuming device (not shown).

  Of the hydrogen contained in the fuel gas supplied to the anode 23, excess hydrogen that was not consumed by the power generation reaction in the fuel cell unit 12 is discharged from the anode 23 and passes through the anode exhaust gas flow path L <b> 6 to the combustion unit 5. Supplied and burned as a combustible gas. A combustion oxygen supply path L2 is connected to the anode exhaust gas flow path L6.

Operation is performed such that the supply amount of the power generation oxygen gas supplied to the cathode 24 through the power generation oxygen supply path L4 is measured by the power generation oxygen flow meter 20, and the measured flow rate becomes a preset target flow rate. The control unit 3 adjusts the output of the power generation oxygen blower 13 (specifically, the rotational speed of a blower fan, etc.). When the power generation oxygen blower 13 is not operating, for example, when the operation is stopped, the third on-off valve 14 is closed.

  Excess power generation oxygen gas discharged from the fuel cell unit 12 is exhausted to the outside after passing through the water tank 15 through the power generation oxygen discharge path L5. Since the surplus oxygen gas for power generation may contain a large amount of water present in the cathode 24, the water is collected in the water tank 15. In other words, in the fuel cell according to the present embodiment, when the operation is stopped, the entire fuel cell covered with the casing is filled with water to prevent oxygen from entering and deterioration of the electrode due to oxidation. Measures such as prevention are taken.

  Then, the operation control unit 3 adjusts the output of the power generation oxygen blower 13 so that the flow rate per unit time of the power generation oxygen gas becomes a target flow rate commensurate with the output power of the fuel cell unit 12, and the power detection unit While the output power detected at 19 is constant, the output voltage of the fuel cell unit 12 detected by the voltage detection unit 18, specifically, the output voltage of the cell C showed fluctuations exceeding a predetermined allowable range. At this time, it is determined that a problem has occurred in the supply of the oxygen gas for power generation to the cathode 24.

  In addition, as shown in FIG. 3, the operation control unit 3 includes a voltage detection step (step # 1), a failure determination step (step # 2), a failure cause estimation step (step # 3), a countermeasure, Step (Step # 4) is executed.

  In the voltage detection step (# 1), the voltage detection unit 18 detects the output voltage while the output power of the fuel cell unit 12 detected by the power detection unit 19 is constant. The voltage detection unit 18 detects a voltage generated by the plurality of cells C in the fuel cell unit 12 and obtains an average value (referred to as an average cell voltage). FIG. 4 shows data of actual measurement values measured by the present applicant. FIG. 4 shows data on the operating state in the stable operation of the fuel cell unit 12. In this example, when the output is stable, the output power is about 700 W and the average cell voltage is about 730 mV.

  In the failure determination step (# 2), it is determined that a failure has occurred in the supply of the oxygen gas for power generation to the cathode 24 when the output voltage detected in the voltage detection step shows a fluctuation exceeding a predetermined allowable range. To do. Specifically, the standard deviation for the output voltage of a single cell C is obtained, and the standard deviation is compared with a preset threshold value. If the standard deviation is smaller than the threshold value, the normal operation is performed. If the standard deviation is larger than the threshold value, it is determined that a problem has occurred in the supply of the oxygen gas for power generation to the cathode 24. For the standard deviation, voltage data of an average value for 5 seconds of the output voltage of the cell C is obtained, and the standard deviation for 12 pieces of the voltage data is obtained by calculation. Since the fluctuation range of the output voltage varies depending on the magnitude of the output power, the threshold value may be set to a different value according to the magnitude of the output power of the fuel cell unit 12 at that time. For example, when the output power is 250 W or more and less than 400 W, the threshold is 4 mV, when the output power is 400 W or more and less than 600 W, the threshold is 5 mV, and when the output power is 600 W or more and 700 W or less, the threshold is 6 mV. be able to.

  In the failure cause estimation step (# 3), the current output of the power generation oxygen blower 13 is a reference output when the flow rate per unit time of the power generation oxygen gas is set to a target flow rate corresponding to the output power of the fuel cell unit 12. If it is larger than the set value, it is estimated that there is a problem in the supply of the oxygen gas for power generation due to the increase in the flow resistance of the oxygen gas for power generation, and the current output of the blower 13 for power generation oxygen Is not larger than the set value from the reference output, it is estimated that a failure in the supply of oxygen gas for power generation due to the blower 13 for oxygen for power generation has occurred.

  That is, the change characteristics between the output power of the fuel cell unit 12 and the flow rate per unit time (reference output) of the oxygen gas for power generation corresponding to the output power are determined and determined in advance through experiments or the like. If the current output of the power generation oxygen blower 13 is larger than the set value from the reference output, the power generation oxygen gas flows less than the current output of the power generation oxygen blower 13, that is, for power generation. It can be assumed that the flow resistance of the oxygen gas is increased.

  However, if it is determined that there is a problem with the supply of oxygen gas for power generation at the cathode 24, but the current output of the power generation oxygen blower 13 is not greater than the set value from the reference output, It is determined that a problem caused by the oxygen blower 13, specifically, a problem caused by water entering the power generation oxygen blower 13 has occurred.

  The cause of the water intrusion into the power generation oxygen blower 13 is that the third on-off valve 14 and the fourth on-off valve 16 have failed to open, and the water enclosed in the fuel cell unit 12 is generated by the power generation oxygen supply path L4. It is conceivable to flow into the power generation oxygen blower 13 through For example, when fuel gas is supplied through the reforming unit 4 to avoid deterioration due to oxidation of the electrodes when the operation is stopped, or when the operation is started, the exhaust gas in the combustion unit 5 is removed. When the combustion oxygen blower 7 is operated, water may enter.

  FIG. 5 shows data of actual measurement values when water enters the power generation oxygen blower 13. As is apparent from this figure, it can be seen that the output voltage of the fuel cell unit 12 varies greatly and the standard deviation increases. In the configuration shown in FIG. 5, when the output voltage of the fuel cell unit 12 decreases, the output power of the fuel cell unit 12 is also reduced. The output power varies depending on the change in the output voltage. It has fluctuated. When water enters the power generation oxygen blower 13 as described above, the output voltage fluctuates greatly. Therefore, the fluctuation is discriminated by comparing the standard deviation with a threshold value (for example, 6 mV in the examples shown in FIGS. 4 and 5). Can do. Even in this case, the voltage detection step is preferably performed while the output power of the fuel cell unit 12 is constant. That is, in the example shown in FIG. 5, it is good to carry out in the specific period (period shown by Q in FIG. 5 etc.) where output power is constant.

  In the countermeasure process (# 4), the operation control unit 3 determines that a problem has occurred in the supply of the oxygen gas for power generation to the cathode 24 in the malfunction determination process (# 2), and the malfunction cause estimation process. In (# 3), when it is estimated that a malfunction caused by the oxygen generator blower 13 has occurred, a low output operation for setting the output power of the fuel cell unit 12 to a predetermined low output state is performed for a predetermined period.

  For example, the output of the fuel cell unit 12 is set to a low output (for example, 250 W) lower than the maximum output (700 W), and the low output operation is performed. Then, the low output operation is continued until it is considered that water has been discharged from the power generation oxygen blower 13, that is, until no failure is determined in the failure determination step. If it is a low output operation, the output of the power generation oxygen blower 13 can be kept low, and the power generation oxygen blower 13 is less likely to be damaged.

  Further, when the operation is stopped and the fuel gas is supplied through the reforming unit 4, the power generation oxygen blower 13 is operated in a low output state. That is, when the fuel cell unit 12 is not generating power, when the pressure from the cathode 24 toward the power generation oxygen blower 13 is applied, for example, when the exhaust gas treatment of the combustion unit 5 at the start of operation of the fuel cell unit 12 is performed, The oxygen blower 13 is operated in a low output state.

  By operating in such a low output state, water can be discharged from the power generation oxygen blower 13 while avoiding early breakdown of the power generation oxygen blower 13.

[Another embodiment]
(1) In the above embodiment, the operation control unit 3 executes the failure cause estimation process, and when the power generation oxygen blower is the cause, the low power operation is performed in the countermeasure process. Instead, the low output operation may be performed whenever it is determined that a defect has occurred in the defect determination step without executing the defect cause estimation step.

(2) In the above embodiment, the low output operation is performed as the countermeasure process. However, instead of this configuration, the operation of the fuel cell unit may be stopped.

(3) In the above embodiment, in the defect determination step, the standard deviation of the output voltage is obtained and the standard deviation is compared with the threshold value to determine the defect. However, the fluctuation amount of the output voltage per unit time The defect may be determined based on the output voltage, or the defect may be determined based on the rate of change of the output voltage.

  The configuration disclosed in the above embodiment (including another embodiment, the same shall apply hereinafter) can be applied in combination with the configuration disclosed in the other embodiment, as long as no contradiction occurs. The embodiment disclosed in this specification is an exemplification, and the embodiment of the present invention is not limited to this. The embodiment can be appropriately modified without departing from the object of the present invention.

  The present invention can be applied to a fuel cell system.

DESCRIPTION OF SYMBOLS 3 Operation control part 4 Reforming part 5 Combustion part 12 Fuel cell part 13 Blower for power generation oxygen 18 Voltage detection part 19 Electric power detection part 23 Anode 24 Cathode

Claims (10)

A reforming section for reforming raw fuel to generate fuel gas;
A fuel cell unit having an anode to which the fuel gas generated in the reforming unit is supplied, and a cathode to which power generation oxygen gas is supplied;
A combustion section for burning a fuel component in exhaust fuel gas discharged from the anode after being used in a power generation reaction in the fuel cell section;
A power generation oxygen blower for supplying the power generation oxygen gas to the cathode;
A fuel cell system comprising an operation control unit,
A voltage detection unit for detecting an output voltage of the fuel cell unit;
A power detection unit for detecting output power of the fuel cell unit,
The operation controller is
Adjusting the output of the power generation oxygen blower so that the flow rate per unit time of the power generation oxygen gas becomes a target flow rate commensurate with the output power of the fuel cell unit,
Supply of the oxygen gas for power generation to the cathode when the output voltage detected by the voltage detector shows a fluctuation exceeding a predetermined allowable range while the output power detected by the power detector is constant A fuel cell system that determines that a failure has occurred.   When the operation control unit determines that there is a problem in the supply of the oxygen gas for power generation to the cathode, the operation control unit performs a low output operation for setting the output power of the fuel cell unit to a predetermined low output state for a predetermined period. The fuel cell system according to claim 1 to be performed. The operation controller is
It is determined that there is a problem in the supply of the oxygen gas for power generation to the cathode, and the current output of the oxygen blower for power generation indicates the flow rate per unit time of the oxygen gas for power generation as the fuel cell. When the target flow rate corresponding to the output power of the unit is larger than the set value from the reference output, there is a problem in the supply of the oxygen gas for power generation due to an increase in the flow resistance of the oxygen gas for power generation Determine that it has occurred,
When it is determined that there is a problem in the supply of the oxygen gas for power generation to the cathode and the current output of the oxygen generator blower is not greater than the set value from the reference output, the power generation 3. The fuel cell system according to claim 1, wherein the fuel cell system determines that there is a problem in the supply of the oxygen gas for power generation caused by the oxygen blower. 4. The operation controller is
When it is determined that there is a problem in the supply of the oxygen gas for power generation to the cathode and the current output of the oxygen generator blower is not greater than the set value from the reference output, the power generation 4. The fuel cell system according to claim 3, wherein it is determined that a failure in the supply of the oxygen gas for power generation due to water intrusion into the oxygen blower has occurred. A fuel cell unit having a reforming unit that reforms raw fuel to generate fuel gas, an anode to which the fuel gas generated in the reforming unit is supplied, and a cathode to which oxygen gas for power generation is supplied A combustion section for burning a fuel component in the exhaust gas discharged from the anode after being used in a power generation reaction in the fuel cell section, and a power generation oxygen for supplying the power generation oxygen gas to the cathode A fuel cell system comprising a blower for a vehicle,
The fuel cell system includes a voltage detection unit that detects an output voltage of the fuel cell unit, and a power detection unit that detects output power of the fuel cell unit,
The output of the power generation oxygen blower is adjusted so that the flow rate per unit time of the power generation oxygen gas becomes a target flow rate corresponding to the output power of the fuel cell unit,
While the output power detected by the power detection unit is constant, a voltage detection step of detecting an output voltage by the voltage detection unit;
A failure determination step of determining that a failure has occurred in the supply of the oxygen gas for power generation to the cathode when the output voltage detected in the voltage detection step shows a fluctuation exceeding a predetermined allowable range. Operation method of fuel cell system.   When it is determined in the failure determination step that a failure has occurred in the supply of the oxygen gas for power generation to the cathode, a low output operation for setting the output power of the fuel cell unit to a predetermined low output state is performed for a predetermined period. The operation method of the fuel cell system according to claim 5, further comprising a countermeasure step to be performed. In the failure determination step, when it is determined that a failure has occurred in the supply of the oxygen gas for power generation to the cathode,
If the current output of the power generation oxygen blower is larger than a set value from a reference output when the flow rate per unit time of the power generation oxygen gas is set to a target flow rate corresponding to the output power of the fuel cell unit , Presuming that there is a problem in the supply of oxygen gas for power generation due to an increase in flow resistance of the oxygen gas for power generation,
If the current output of the power generation oxygen blower is not greater than or equal to the set value from the reference output, it is estimated that the power generation oxygen gas supply failure caused by the power generation oxygen blower has occurred. The method for operating a fuel cell system according to claim 5, further comprising a failure cause estimation step.   When it is estimated in the failure cause estimation step that a failure in the supply of oxygen gas for power generation due to the blower for oxygen for power generation has occurred, the output power of the fuel cell unit is set to a predetermined low output state The operation method of the fuel cell system according to claim 7, further comprising a countermeasure step for performing a low output operation for a predetermined period.   In the failure cause estimation step, when it is estimated that a failure in the supply of oxygen gas for power generation due to the blower for oxygen for power generation has occurred, at a predetermined timing during which the fuel cell unit does not generate power, The fuel cell system operating method according to claim 7 or 8, wherein the power generation oxygen blower is operated to flow the power generation oxygen gas from the power generation oxygen blower toward the cathode.   The operation method of the fuel cell system according to claim 9, wherein the predetermined timing is a timing at which a pressure from the cathode toward the power generation oxygen blower is applied while the fuel cell unit is not generating power.

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