JP6394875B2 - Fuel cell system - Google Patents

Description

  The present invention relates to a fuel cell system having a function of adjusting the temperature of a fuel cell to be lowered in response to an output request.

  In recent years, research and development of automobiles using fuel cells have been promoted due to increasing interest in global environmental problems. Among various types of fuel cells, the solid oxide fuel cell (SOFC), which has high efficiency, uses electrochemical gas with hydrogen, carbon monoxide, and hydrocarbons, using gas containing a lot of hydrogen as fuel and oxygen as oxidant. Electricity is generated by reaction, but there are also fuels that use reformed gas obtained by reforming various liquid fuels.

  Also, when used as a power source for automobiles, solid oxide fuel cells are frequently started and stopped unlike stationary batteries, so that they are liable to deteriorate and a decrease in power generation output directly affects vehicle running performance. Affects.

  As a fuel cell system using a solid oxide fuel cell, for example, as described in Patent Document 1, a temperature increase caused by a decrease in the performance of the fuel cell is detected, the fuel amount is decreased, and the air amount is increased. As a result, the temperature of the fuel cell is lowered, and an excessive temperature rise is prevented to suppress performance deterioration.

JP 2013-164928 A

  However, since the solid oxide fuel cell has a temperature distribution during power generation, when the temperature rises due to deterioration, the place where the operation upper limit temperature is reached is partially limited, and the place where the temperature is reached is limited. It is impossible to measure accurately. Even if a large number of measurement points are provided, the cost is high. In addition, when the amount of fuel for lowering the temperature of the fuel cell is reduced as in the conventional fuel cell system, the power generation output itself is inevitably reduced. Therefore, it has been a problem to solve these problems.

  The present invention has been made paying attention to the above-mentioned conventional problems, and detects a rise in the maximum temperature accompanying a decrease in the performance of the fuel cell, changes the operating conditions of the fuel cell, and maintains the power generation output while maintaining the power generation output. It aims at providing the fuel cell system which can suppress the temperature of a battery below to upper limit temperature.

A fuel cell system according to the present invention includes a fuel cell having a structure in which an electrolyte layer is sandwiched between an anode electrode and a cathode electrode, an air supply device that supplies air to the cathode electrode of the fuel cell, and controls the fuel cell and the air supply device. An operation control device is provided. In the fuel cell system, the operation control device detects the deterioration of the fuel cell based on the power generation output maintaining means for maintaining the power generation output of the fuel cell constant and the power generation voltage in the same power generation state by the power generation output maintaining means The battery deterioration detecting means, the air increasing means for controlling the air supply device to increase the amount of air supplied to the cathode when the deterioration of the fuel cell is detected by the battery deterioration detecting means, and the air increase of the air increasing means Air increase effect confirmation means for confirming the effect of the increase in the air supplied to the cathode electrode by judging the temperature decrease of the fuel cell by the amount of decrease in the generated voltage, the confirmation result of the effect of the air increase by the air increase effect confirmation means, and And operating condition setting means for resetting the operating condition of the fuel cell based on the air increase value by the air increasing means .

According to the fuel cell system of the present invention, an increase in the maximum temperature accompanying a decrease in the performance of the fuel cell is detected, the operating condition of the fuel cell is changed, and the temperature of the fuel cell is kept below the upper limit temperature while maintaining the power generation output. Can be suppressed. As a result, when the fuel cell system is applied to a vehicle, even if the fuel cell is deteriorated, the intended vehicle running performance can be maintained. Further, the fuel cell system can detect the deterioration of the fuel cell with a simple configuration by adopting the above-described battery deterioration detecting means, and can contribute to cost reduction and high accuracy of operation control. Further, the fuel cell system can maintain the power generation amount while suppressing the performance deterioration when the fuel cell is deteriorated by adopting the air increase effect confirmation means and the operating condition setting means.

1 is a block diagram showing a configuration of a fuel cell system according to a first embodiment of the present invention. It is a graph which shows the change (a) of fuel cell temperature and the change (b) of gas temperature accompanying the power generation performance degradation of a fuel cell system. FIG. 5 is a characteristic diagram showing the relationship between the degree of degradation of power generation performance of the fuel cell system and the maximum temperature and average temperature of the fuel cell. FIG. 6 is a characteristic diagram showing a relationship between the degree of degradation of power generation performance of the fuel cell system and the maximum temperature of the fuel cell. It is a graph which shows the change (a) of a fuel cell temperature and the change (b) of gas temperature accompanying the air increase of a fuel cell system. It is a characteristic view which shows the relationship between the deterioration degree of the power generation performance of a fuel cell system, and an output voltage. It is a figure which shows the relationship between the voltage drop target value at the time of setting the maximum temperature of a fuel cell to below upper limit temperature by the deterioration degree of the power generation performance of a fuel cell system, and air increase. It is a fuel cell temperature and output current graph accompanying the power generation performance degradation of the fuel cell of a fuel cell system. It is a flowchart which shows the process of the operation control apparatus of a fuel cell system. It is a graph explaining the effect at the time of making a gas flow direction different with respect to 1st Embodiment. It is a block diagram which shows 2nd Embodiment of the fuel cell system concerning this invention. It is a block diagram which shows 3rd Embodiment of the fuel cell system concerning this invention.

<First Embodiment>
A fuel cell system 100 shown in FIG. 1 includes a fuel cell 11 having a structure in which an electrolyte layer (not shown) is sandwiched between a cathode electrode 11a and an anode electrode 11b, and air (cathode gas: oxidant) on the cathode electrode 11a of the fuel cell 11. A first air blower 12 as an air supply device for supplying gas), and an operation control device 31 for controlling the fuel cell 11 and the first air blower (air supply device) 12. In this embodiment, the cathode gas is exemplified by air, but the cathode gas is not limited thereto, and may be other than air as long as it contains oxygen.

  The fuel cell 11 is, for example, a solid oxide fuel cell (SOFC), and includes the electrolyte layer, the cathode electrode 11a, and the anode electrode 11b as described above. As an example, the electrolyte layer is 8 mol% yttria stabilized zirconia, the cathode 11a is lanthanum strontium manganite, and the anode 11b is nickel + yttria stabilized zirconia cermet.

  The fuel cell 11 supplies air to the cathode electrode 11a and also supplies the reformed fuel to the anode electrode 11b, thereby generating electric energy by an electrochemical reaction and supplying the electric power to a power demand facility such as a motor. Supply. More specifically, the fuel cell 11 includes a separator that forms an air flow path with the cathode electrode 11a, a separator that forms a fuel flow path with the anode electrode 11b, and the like. Thus, a fuel cell stack is formed.

  In FIG. 1, only the cathode electrode 11a and the anode electrode 11b are shown as the fuel cell 11 for convenience of explaining the reaction gas flow system. However, the fuel cell 11 may be replaced with a fuel cell stack. That is, in the case of the fuel cell stack, the internal configuration includes a flow path for circulating air and fuel to the individual fuel cells 11, so that the external configuration is basically the same distribution system as in FIG. Used.

  The fuel cell system 100 includes an air heating heat exchanger 13, a first fuel pump 14, and a fuel reformer 15. The air heating heat exchanger 13 heats the air sent from the first air blower 12. The first fuel pump 14 supplies fuel (anode gas: fuel gas) such as hydrocarbon fuel to the anode 11 b of the fuel cell 11.

  The fuel reformer 15 is supplied with fuel through the fuel gas flow path Ll by the first fuel pump 14 and is heated by the heat exchanger 16 for heating the reformer, and the fuel is catalytically reacted using the heat. Reform. The reformed fuel (reformed gas including hydrogen gas) is supplied to the anode 11 b of the fuel cell 11.

  The fuel cell system 100 further includes a fuel circulation blower 17, a reformer heating heat exchanger 16, a fuel flow path pressure adjustment valve 18, an exhaust flow path pressure adjustment valve 19, and a combustion burner 23. Yes.

  The fuel circulation blower 17 circulates the fuel exhaust gas discharged from the anode 11 b to the fuel reformer 15. The reformer heating heat exchanger 16 introduces exhaust gas discharged from the cathode electrode 11a through the exhaust gas passage L2, and heats the fuel reformer 15 with the heat of the exhaust gas.

  The fuel flow path pressure regulating valve 18 is provided between the output port of the fuel circulation blower 17 and the exhaust gas flow path L2, and when opened, a part of the fuel exhaust gas discharged from the anode 11b is removed from the exhaust gas flow path L2. To introduce. The exhaust passage pressure regulating valve 19 is provided in the exhaust gas passage L2 near the inlet of the reformer heating heat exchanger 16, and is connected to the reformer heating heat exchanger 16 via the exhaust gas passage L2. Part of the introduced exhaust gas is discharged to the outside.

  The combustion burner 23 causes the air supplied from the second air blower 21 and the fuel supplied from the second fuel pump 22 to be mixed and burned, and is supplied to the cathode 11 a of the fuel cell 11 by the heat. Heat the air.

  Further, in the fuel cell system 100, the first air blower 12, the first fuel pump 14, the second air blower 21, the second fuel pump 22, the exhaust passage pressure regulating valve 19, the fuel passage pressure regulating valve 18, and the fuel Circulating blowers 17 are connected to the operation control device 31, respectively.

  The operation control device 31 is a computer device including, for example, a CPU, a RAM, a ROM, and various operators, and controls each device by transmitting a control signal to each device in response to an output request of the fuel cell 11. It has a function. This operation control device controls the operations of the first air blower 12 and the first fuel pump 14 so that the amount of air and the amount of fuel corresponding to the required output of the fuel cell 11 are the main functions.

  In addition, the operation control device 31 detects the deterioration of the fuel cell 11 by means of a power generation output maintaining unit that maintains the power generation output of the fuel cell 11 constant, a battery deterioration detection unit that detects deterioration of the fuel cell 11, and a cell deterioration detection unit. Air increasing means for controlling the air supply device (first air blower 12) to increase the amount of air supplied to the cathode 11a when detected.

  Further, the operation control device 31 has an air increase effect confirmation means for confirming the effect of the increase in the air supplied to the cathode electrode 11a, and an operation condition setting means for resetting the operation conditions of the fuel cell 11. Here, it is assumed that the air increase by the air supply device (first air blower 12) and the operation control device 31 is performed below the predetermined maximum allowable air amount or below the fuel cell operating upper limit temperature.

  The above-described power generation output maintaining means, battery deterioration detection means, air increase means, air increase effect confirmation means, and operation condition setting means are the software of the computer, and the power generation output maintenance function, battery deterioration detection in the operation control device 31. It can be expressed as a function, an air increase function, an air increase effect confirmation function, and an operating condition setting function.

  Further, the operation control device 31 has a function of issuing a warning when the air increase value reaches a predetermined maximum allowable air amount value or a fuel cell operation upper limit temperature, and the air increase value is determined in advance. It has a function of shifting to an operation mode for reducing the power generation amount of the fuel cell when the maximum allowable value of the air amount or the fuel cell operation upper limit temperature is reached.

  Further, as a more preferred embodiment, the operation control device 31 is configured such that the battery deterioration detection means predicts and detects deterioration of the fuel cell 11 based on a power generation voltage in a power generation state with the same output set in advance. The battery deterioration detecting means can be a means for predicting and detecting deterioration of the fuel cell 11 based on the gas inlet / outlet temperature of at least one of the anode 11b and the cathode 11a of the fuel cell 11.

  Further, as a more preferred embodiment, the operation control device 31 is a means for the air increase effect confirmation means to confirm the effect of the increase in the air supplied to the cathode electrode 11a due to the temperature drop of the fuel cell 11, and the operation condition setting means. Is a means for resetting the air increase value as the operating condition.

  The air increase effect confirmation means is a means for confirming the effect of the increase in the air supplied to the cathode electrode 11a due to the temperature decrease of the fuel cell 11 by judging the temperature decrease of the fuel cell 11 by the decrease amount of the generated voltage. You can also.

  Further, the air increase effect confirmation means determines the temperature decrease of the fuel cell 11 based on the amount of decrease in the generated voltage, and in addition, the gas inlet / outlet temperature of at least one of the anode 11b and the cathode 11a of the fuel cell 11 Based on the above, it can also be a means for confirming the effect of the increase in the amount of air supplied to the cathode 11a.

  Further, the fuel cell system 100 includes an inlet temperature sensor Tcin that measures the temperature of air introduced into the cathode electrode 11a, an outlet temperature sensor Tcout that measures the temperature of exhaust gas discharged from the cathode electrode 11a, and the fuel cell 11. A separator temperature sensor Ts for measuring the separator temperature, an outlet temperature sensor Taout for measuring the temperature of the fuel exhaust gas discharged from the anode 11b, and the like. Measurement values obtained by these temperature sensors Tcin, Tcout, Ts, and Taout are input to the operation control device 31.

Next, the operation at the start of operation of the fuel cell system 100 will be described.
That is, the fuel cell system 100 drives the combustion burner 23 to start up the system. In the fuel cell system 100 during power generation operation, the operating temperature is changed by heating the fuel cell 11 with an electric heater (not shown) or the like, and the amount of air supplied to the cathode electrode 11a of the fuel cell 11 and the anode electrode 11b The amount of fuel to be supplied is changed to correspond to the change in output power.

  At the start of operation, fuel and air are supplied to the combustion burner 23 by operating the second fuel pump 22 and starting the second air blower 21 as an initial operation. The combustion burner 23 mixes and burns fuel and air, and supplies the combustion gas to the cathode 11 a of the fuel cell 11. Thereby, the temperature of the fuel cell 11 is raised by the heat of the combustion gas supplied from the combustion burner 23.

  Thereafter, when the temperature of the fuel cell 11 reaches a rated temperature (for example, 650 ° C.), the fuel cell system 100 stops the combustion burner 23 and switches to the output of the first air blower 12 as an air supply device. The air sent out by the first air blower 12 passes through the low temperature side (the side that absorbs heat) of the air heating heat exchanger 13, and is then introduced into the oxidant gas supply port of the cathode electrode 11a. At this time, the high temperature gas discharged from the reformer heating heat exchanger 16 is introduced to the high temperature side (the side from which heat is released) of the air heating heat exchanger 13. For this reason, the air sent out from the first air blower 12 is heated by heat exchange with the high-temperature gas and introduced into the cathode 11a.

  In addition, since the air heated by the air heating heat exchanger 13 is usually at a temperature lower by about 200 to 300 ° C. than the rated temperature of the fuel cell 11, immediately after switching from the combustion burner 23 to the first air blower 12. In this case, the temperature of the cathode electrode 11a temporarily decreases. However, the temperature of the cathode electrode 11a rises and reaches the rated temperature due to the heat generation of the battery itself due to the start of power generation. For this reason, it becomes possible to supply electric power to an electric power demand installation. That is, when the fuel cell system 100 is used in a vehicle, the fuel cell system 100 is in a state in which power can be supplied to a motor that is a power demand facility to drive the vehicle.

  Next, the operation state of the fuel cell 11 when the fuel cell system 100 is in an operating state will be described. That is, in the fuel cell system 100, the temperature of the air introduced into the cathode electrode 11a is, for example, 200 ° C. to 300 ° C. lower than the normal operating temperature of the fuel cell 11 (650 ° C. to 750 ° C.). ing. For this reason, the air introduced into the cathode electrode 11a is heated by the heat energy generated with the power generation of the fuel cell 11, and is discharged from the cathode electrode 11a. At this time, the air also functions as a cooling fluid for the fuel cell 11 and the fuel cell stack. In the rated operation, the amount of heat generated by the power generation corresponding to the operating temperature of the fuel cell 11 and the amount of heat transferred to the gas containing air are balanced, so the temperature of the fuel cell 11 is a restriction on the thermal characteristics of the material. The operating conditions (gas flow rate) are set so as to be lower than the upper limit temperature.

  Here, FIG. 2 is a graph showing a change (a) in the fuel cell temperature and a change (b) in the gas temperature (cathode electrode gas temperature) accompanying the deterioration of the power generation performance of the fuel cell system 100. In FIG. 2, the horizontal axis indicates the position of the fuel cell (described as “cell” in the figure) 11. This fuel cell has a configuration in which a fuel introduction portion and an air discharge portion are arranged on one side, and a fuel discharge portion and an air introduction portion are arranged on the other side. As a result, the fuel cell is in a state where the flow direction of the fuel (anode gas) and the flow direction of the air (cathode gas) face each other (a state opposite to each other), as indicated by arrows in the drawing.

In a state where there is no deterioration of the fuel cell 11, as shown as “BASE” in FIGS. 2 (a) and 2 (b), the amount of power generated by the fuel cell 11 is secured and the fuel is set so that the entire surface is below the upper limit temperature. The operating conditions of the battery 11 are set. To do this, the operation control device 31, a power output maintaining means for maintaining the power output of the fuel cell 11 constant.

  In contrast, when the fuel cell 11 is deteriorated and the power generation performance is reduced, a part of the generated energy is changed to heat generation, so that the increased heat is mainly transmitted to the cathode electrode air, but all the heat generation amount is generated. Since the temperature of the fuel cell 11 itself rises because it cannot be absorbed by air, the internal temperature difference becomes significant in the fuel cell 11 with respect to the state where the power generation performance is not deteriorated. Specifically, as shown as “deterioration” in FIGS. 2A and 2B, the temperature change is small on the fuel introduction side (air discharge side) on the left side in FIG. On the other hand, on the fuel discharge side (air introduction side) on the right side in FIG. 2A, the originally high temperature further rises, and a portion exceeding the upper limit temperature appears.

  This is because the power generation performance of the fuel cell 11 has deteriorated, but on the fuel introduction side (air electrode gas outlet side) where the temperature change is small, the power generation amount is not significantly different from that before the deterioration, but is small. For this reason, in order to keep the power generation amount constant, the power generation amount increases and the temperature partially increases on the fuel discharge side (air introduction side). In this way, a phenomenon occurs in which the temperature of the fuel cell 11 rises on the fuel discharge side (air introduction side).

  FIG. 3 shows the relationship between the degree of degradation of the power generation performance of the fuel cell system, the maximum temperature (Tmax) and the average temperature (Tave) of the fuel cell 11. Here, the degree of deterioration refers to the initial power generation voltage in a state where the fuel cell 11 is not deteriorated and is generating a constant output, and the power generation voltage when the power generation voltage is lowered as the power generation performance deteriorates. And the ratio.

  As is apparent from FIG. 3, when the degree of deterioration of the fuel cell 11 increases, the average temperature (Tave) increases to generate a constant output, but the maximum temperature (Tmax) increases more than that. Based on this relationship, the degree of deterioration of the fuel cell 11 can be predicted by comparing the power generation voltage of the fuel cell 11 when generating a certain amount of power with the power generation voltage when there is no deterioration, and FIG. The maximum temperature of the fuel cell can be predicted as shown in FIG. This is performed by the deterioration detecting means for detecting the deterioration of the fuel cell 11 in the operation control device 31.

  Therefore, when the fuel cell 11 is deteriorated, only a partial temperature rise occurs inside the cell. Therefore, the temperature of the portion exceeding the upper limit temperature is suppressed while maintaining a constant output. For this purpose, the amount of air supplied from the fuel discharge side (air electrode gas introduction side) is increased without changing the fuel amount. This is done by setting the air supply device (first air blower 12) to increase the amount of air supplied to the cathode electrode 11a when the deterioration of the fuel cell 11 is detected by the battery deterioration detection means in the operation control device 31. Air increasing means to control.

  5A and 5B show the state of the fuel cell 11 when air is increased. The flow directions of the fuel (anode gas) and air (cathode gas) are the same as those in FIG.

  As shown in FIG. 5A, the heat of the fuel cell 11 moves to the air more than before the increase due to the increase in air. The air carries the received heat quantity to the fuel introduction side (air discharge side), and raises the temperature of the fuel introduction side, which is the left side in FIG. For this reason, in the fuel cell 11, the power generation amount increases on the fuel introduction side, and the power generation amount on the fuel discharge side decreases as the power generation balance of the entire fuel cell, so the temperature on the fuel discharge side decreases. The fuel cell 11 as a whole reduces the temperature width inside the battery by increasing the amount of air. That is, it is possible to reduce the difference in the amount of power generation, which makes it possible to lower the maximum temperature of the fuel cell 11 and keep it below the upper limit temperature while maintaining a constant output.

  On the other hand, when the maximum temperature is lowered to below the upper limit temperature while increasing the air to maintain a constant output, the power generation voltage of the fuel cell 11 is lower than before increasing the air, as shown in FIG. Power is generated in the state. This is because power generation at a high voltage due to the high temperature state of the fuel cell 11 before increasing the amount of air is alleviated. Therefore, when the amount of air is increased, the amount of decrease in the output voltage can be used as an index to detect that the temperature of the fuel cell 11 has become the upper limit temperature or less.

  FIG. 7 shows an example of the target voltage drop when the air is increased to lower the maximum temperature of the fuel cell 11. Since the temperature distribution having the highest temperature portion in the battery cannot be detected by the fuel and air inlet / outlet temperatures, the voltage drop amount is effectively used as an index.

  From the above, as shown in FIG. 8, the variation in the temperature of the fuel cell 11 caused by the amount of power generation varies depending on the site in the power generation state, so that the maximum temperature does not exceed the maximum use temperature in the initial operation state. It is set.

  When the fuel cell 11 gradually deteriorates in power generation performance as power generation continues, the amount of heat generated by power generation increases, and even if the same amount of power generation can be maintained, the temperature partially rises and exceeds that temperature. It becomes a temperature that affects the material and structure and promotes a decrease in the power generation performance of the cell, and is in a state close to or exceeding the use upper limit temperature (state T1 in FIG. 8).

  At this time, since the power generation voltage has decreased with deterioration, the fuel cell 11 detects this voltage decrease and predicts and detects deterioration to increase only the air. When the air is increased, the fuel cell 11 changes its temperature state, and as described with reference to FIGS. 2 to 8, the maximum temperature is lowered, and the low temperature part is raised in temperature. A state (state T2 in FIG. 8) in which the maximum temperature can be lowered while generating the same output is realized. Thereby, the fuel cell 11 can continue the operation | movement which maintained the electric power generation amount, suppressing performance degradation.

FIG. 9 is a flowchart showing the processing steps of the operation control device 31.
The operation control device 31 uses the function of the power generation output maintaining means to set the first air blower 12 (air supply device) and the first fuel so that the power generation output of the fuel cell 11 is maintained at a constant air amount and fuel amount. The operation of the pump 14 is controlled.

  Then, when control to supply to the fuel cell 11 is started (Start), in step S101, the fuel cell 11 is detected based on the power generation voltage when the same output is generated by the battery deterioration detection unit using the function of the power generation output maintaining unit. Detect degradation of Specifically, the deterioration of the performance of the fuel cell 11 is predicted and detected from the decrease in the output voltage.

  Next, after predicting and detecting the deterioration of the performance of the fuel cell 11, the operation control device 31 controls the first air blower 12 by the air increasing means and supplies it to the cathode 11 a of the fuel cell 11 in step S <b> 102. Increase air volume. At this time, the air supplied to the fuel cell 11 can be increased by controlling the second air blower 21. Therefore, the second air blower 21 can be used as the air increasing means.

  In step S103, the effect of increasing the amount of air supplied to the cathode 11a is confirmed by the air increasing effect confirming means. Specifically, a drop in cell power generation voltage accompanying a drop in the maximum temperature due to an increase in air is detected, and a target voltage drop according to the degree of deterioration is confirmed. If this target voltage drop is confirmed, in step S104, it is confirmed that the discharge amount of the first air blower 12 at that time and the control amount corresponding to the discharge amount are within the blower operating range permitted in advance.

In step S104, when the discharge amount of the first air blower 12 and the control amount corresponding to the discharge amount are within the blower operating range allowed in advance (YES), the process proceeds to step S105, and the operating condition setting means As a result, the operating conditions of the fuel cell 11 are reset, and the control returns to Start (Start).

  Further, in step S104, when the discharge amount of the first air blower 12 and the control amount corresponding to the discharge amount are not within the allowable operation range of the blower (NO), that is, the air increase value is a predetermined air amount. When the maximum allowable amount of fuel or the fuel cell operation upper limit temperature is reached, the process proceeds to step S106, where a warning indicating deterioration is output, or a transition to a power reduction mode for reducing the power generation amount of the fuel cell is performed. Then, the control is ended (End).

  In this way, the fuel cell system 100 detects an increase in the maximum temperature associated with a decrease in the performance of the fuel cell 11, changes the operating conditions of the fuel cell 11, and changes the temperature of the fuel cell 11 while maintaining the power generation output. It can be suppressed below the upper limit temperature. As a result, when the fuel cell system 100 is applied to a vehicle, even if the fuel cell 11 is deteriorated, it is possible to maintain the intended vehicle running performance.

  In addition, the fuel cell system 100 employs a battery deterioration detection unit that predicts and detects deterioration of the fuel cell based on a power generation voltage in a predetermined power generation state with the same output, so that the deterioration of the fuel cell 11 can be simplified. It can be detected, and can contribute to cost reduction and high accuracy of operation control.

  Further, the fuel cell system 100 employs cell deterioration detection means that predicts and detects deterioration of the fuel cell 11 based on the gas inlet / outlet temperature of at least one of the anode 11b and the cathode 11a of the fuel cell 11. The deterioration of the fuel cell 11 can be detected with a simple configuration using a minimum number of temperature sensors.

  Further, the fuel cell system 100 includes an air increase effect confirmation means for confirming an effect due to an increase in the amount of air supplied to the cathode electrode 11a due to a temperature drop of the fuel cell 11, and an operation condition setting means for resetting the air increase value as an operation condition. By adopting the above, when the fuel cell 11 deteriorates, it is possible to continue the operation while maintaining the power generation amount while suppressing the performance deterioration.

  Further, the fuel cell system 100 determines the effect of the increase in the amount of air supplied to the cathode 11a due to the decrease in the temperature of the fuel cell 11 by determining the decrease in the temperature of the fuel cell 11 based on the decrease in the generated voltage. By adopting the confirmation means, it is possible to reliably perform control to maintain the power generation amount while suppressing performance deterioration.

  Further, the fuel cell system 100 determines whether the temperature of the fuel cell has decreased based on the amount of decrease in the generated voltage, and in addition, determines the cathode electrode based on the gas inlet / outlet temperature of at least one of the anode and cathode of the fuel cell. By adopting the air increase effect confirmation means for confirming the effect of the increase in the amount of air supplied to the vehicle, it is possible to more reliably perform the control for maintaining the power generation amount while suppressing the performance deterioration.

  Further, the fuel cell system 100 increases the amount of air by the air supply device (first air blower 12) and the operation control device 31 at or below the predetermined maximum allowable air amount or below the fuel cell operating upper limit temperature. Therefore, when the performance of the fuel cell 11 deteriorates, the power generation amount can be maintained while suppressing an excessive temperature rise of the fuel cell 11.

  Further, the fuel cell system 100 has a function of issuing a warning when the operation control device 31 reaches a predetermined maximum allowable air amount or a fuel cell operation upper limit temperature, and an output for reducing the power generation amount of the fuel cell 11. By providing the function of shifting to the lowering mode, it becomes possible to grasp in advance or prevent the fuel cell 11 from being damaged.

  In the above embodiment, as shown in FIGS. 2 and 5, the case where the fuel flow direction and the air flow direction in the fuel cell 11 are opposed to each other has been described. In this case, it is possible to remarkably reduce the maximum temperature and maintain the power generation output only by increasing the amount of air. However, the fuel cell system according to the present invention is not limited in the flow direction of fuel and air.

  As shown in FIG. 10, when the fuel flow direction and the air flow direction are parallel, the amount of heat taken away from the fuel cell 11 by the increased amount of air increases. As a result, the temperature of the fuel cell 11 tends to decrease except in the gas discharge section, and the power generation amount on the discharge side of the anode 11b increases to keep the power generation amount constant without increasing the power generation amount on the gas introduction side. However, the temperature tends to rise rapidly in the gas discharge part. For this reason, although the maximum temperature of the fuel cell 11 tends to be lower than before the increase in air, the maximum cell temperature is suppressed only by increasing the air, compared with the case where the fuel and air are made to face each other. It becomes difficult to do.

  However, when fuel and air are allowed to flow in parallel, the maximum temperature of the fuel cell 11 is in the fuel discharge section, so that the fuel cell 11 is overheated due to deterioration of the fuel cell 11 or the fuel cell is caused by an increase in air. 11, the temperature of the anode 11 b and the cathode 11 a and the temperature at the inlet and outlet of the anode 11, or the separator temperature at the anode outlet, which indicates the maximum temperature of the fuel cell 11, are directly detected. There is an advantage that temperature can be detected and used as an index.

  11 and 12 are block diagrams for explaining the second and third embodiments of the fuel cell system according to the present invention. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

Second Embodiment
A fuel cell system 100 shown in FIG. 11 has the same basic configuration as that of the first embodiment (see FIG. 1), and the first and second air blowers 12 and 21 in the system supply air supplied to the cathode electrode 11a. In order to increase the load without changing the load, an ejector 41 is installed between the first air blower 12 and the cathode electrode 11a.

  In this fuel cell system 100, a part of the exhaust discharged through the high temperature side (the side from which heat is released) of the air heating heat exchanger 13 is transferred to the ejector 41 through the flow passage branch 43 and the reflux passage 42. Then, the flow of air sent out by the first air blower 12 is promoted by the ejector effect, and the air is supplied to the cathode 11a. Thereby, when increasing the amount of air, the amount of air supplied to the fuel cell 11 can be increased without changing the load of the first air blower 12 and the second air blower 21.

<Third Embodiment>
A fuel cell system 100 shown in FIG. 12 has a basic configuration similar to that of the first embodiment (see FIG. 1) and a configuration in which a plurality of fuel cells 11 (or fuel cell stacks) for generating power are installed. In this case, the latter-stage fuel cell 11 that introduces the gas that has passed through the former-stage fuel cell 10 is different from the preceding-stage fuel cell 10 in that both the anode electrode 11b and the cathode electrode 11a have different gas compositions and gas temperature conditions. Since the temperature increases, the influence of the cell temperature due to deterioration is likely to occur significantly in the rear stack 11.

  Therefore, the fuel cell system 100 has a structure in which an air bypass passage 44 is installed so that air is increased only in the cathode electrode 11a of the subsequent fuel cell 11 when the deterioration of the fuel cells 10 and 11 is detected. Thus, the maximum temperature of the fuel cell 10 can be effectively lowered by increasing the amount of air only to the cathode electrode 11a of the fuel cell 11 that needs to increase the amount of air.

  The configuration of the fuel cell system according to the present invention is not limited to the above embodiments, and can be appropriately changed without departing from the gist of the present invention.

11 Fuel Cell 11a Cathode Electrode 11b Anode Electrode 12 First Air Blower (Air Supply Device)
13 Heat exchanger for air heating 14 First fuel pump 15 Fuel reformer 16 Heat exchanger for reformer heating 17 Fuel circulation blower 18 Fuel flow path pressure regulation valve 19 Exhaust flow path pressure regulation valve 21 Second air blower 22 Second fuel pump 23 Combustion burner 31 Operation control device 42 Recirculation passage 44 Air bypass passage 100 Fuel cell system

Claims (6)

A fuel cell having sandwiched an electrolyte layer with an anode electrode and a cathode electrode, and an air supply device for supplying air to the cathode of the fuel cell, the operation control device for controlling the fuel cell and the air supply device Prepared,
The operation control device is
A power generation output retention means for maintaining the power output of the fuel cell at a constant,
Battery deterioration detecting means for detecting deterioration of the fuel cell based on a power generation voltage in a power generation state of the same output by the power generation output maintaining means ;
Air increasing means for controlling the air supply device so as to increase the air supplied to the cathode electrode upon detection of the deterioration of the fuel cell by the battery deterioration detecting means,
An air increase effect confirmation means for confirming the effect of the increase in the air supplied to the cathode electrode by judging the temperature decrease of the fuel cell due to the air increase of the air increase means based on the decrease amount of the generated voltage ;
It characterized in that it has confirmed the result of the effect of air increase, and the operating condition setting means for resetting the operating conditions of the fuel cell on the basis of the air increase value by the air increasing unit by the air increasing effect confirmation means fuel cell system. 2. The fuel according to claim 1 , wherein the battery deterioration detecting means is means for predicting and detecting deterioration of the fuel cell based on a gas inlet / outlet temperature of at least one of an anode electrode and a cathode electrode of the fuel cell. Battery system. In addition to the fact that the air increase effect confirmation means determines the temperature decrease of the fuel cell by the amount of decrease in the generated voltage, the air increase effect confirmation means 3. The fuel cell system according to claim 1 , wherein the fuel cell system is a means for confirming an effect due to an increase in the amount of air to be supplied.   2. The fuel cell system according to claim 1, wherein the increase in air by the air supply device and the operation control device is performed below a predetermined maximum allowable air amount or below a fuel cell operation upper limit temperature. Operation control device, increase value of air, the maximum allowable value of a predetermined amount of air, or when it reaches the fuel cell operating upper limit temperature, any of the preceding claims, characterized in that it has a function of issuing a warning The fuel cell system according to claim 1. The operation control device has a function of shifting to an output reduction mode for reducing the power generation amount of the fuel cell when the air increase value reaches a predetermined maximum allowable air amount or a fuel cell operation upper limit temperature. The fuel cell system according to claim 1 , wherein:

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